Cyclic Fatty Acids in Food: An Under-Investigated Class of Fatty Acids

Cyclic fatty acids are an unusual class of minor fatty acids generally produced by bacteria and less frequently by plants. Among plants, the most known cyclic fatty acid is sterculic acid (9, 10-methyleneoctadecenoic acid) produced by Sterculia foetida. Bacteria (e.g., lactic acid bacteria) synthetize cyclopropane fatty acids, such as dihydrosterculic acid (9, 10-methylene octadecanoic acid) and lactobacillic acid (11, 12 methylene octadecanoic acid), to strength their membrane, improving their resistance to environmental stress. Another class of cyclic fatty acids is omegacyclohexyl fatty acids, present in milk and probably produced by rumen bacteria. Cyclopropane and omega-cyclohexyl fatty acids have been recently found in bovine meat and dairy products, representing important foodstuffs in human diet. In this chapter, a review of literature data concerning the presence of cyclic fatty acids in foods, their metabolism in humans, and their potential bioactivity will be provided. The role of some cyclic fatty acids as molecular markers for food authenticity will also be highlighted.

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title: Animal Fat Composition and Modification
abstract: This chapter discusses the classification of lipids, with detailed information concerning fatty acids, their structures, and nomenclature, found in meat animals. A short discussion is presented regarding the analytical procedures that are presently utilized for fatty acid analysis of various meat animal tissues. Advanced technology has helped the analytical analysis immensely. Detailed information is presented regarding differences in fatty acid composition by species (ruminants versus nonruminants), breeds, sex, diets, and environmental factors. Furthermore, a comparison of milk and butter fatty acid composition is discussed; however, 90% of the milk consumed is produced by cattle with the remaining predominantly produced by other ruminants species (goats, sheep, buffalo). Detailed information is provided regarding procedures that may be incorporated to change the fatty acid composition of meat animal lipid depots, ranging from 10% to 40%. Some discussion is provided with regard to the health benefits that may occur from changing the composition of lipids in meat animals.

title: Significance of long chain polyunsaturated fatty acids in human health
abstract: In the last decades, the development of new technologies applied to lipidomics has revitalized the analysis of lipid profile alterations and the understanding of the underlying molecular mechanisms of lipid metabolism, together with their involvement in the occurrence of human disease. Of particular interest is the study of omega-3 and omega-6 long chain polyunsaturated fatty acids (LC-PUFAs), notably EPA (eicosapentaenoic acid, 20:5n-3), DHA (docosahexaenoic acid, 22:6n-3), and ARA (arachidonic acid, 20:4n-6), and their transformation into bioactive lipid mediators. In this sense, new families of PUFA-derived lipid mediators, including resolvins derived from EPA and DHA, and protectins and maresins derived from DHA, are being increasingly investigated because of their active role in the “return to homeostasis” process and resolution of inflammation. Recent findings reviewed in the present study highlight that the omega-6 fatty acid ARA appears increased, and omega-3 EPA and DHA decreased in most cancer tissues compared to normal ones, and that increments in omega-3 LC-PUFAs consumption and an omega-6/omega-3 ratio of 2–4:1, are associated with a reduced risk of breast, prostate, colon and renal cancers. Along with their lipid-lowering properties, omega-3 LC-PUFAs also exert cardioprotective functions, such as reducing platelet aggregation and inflammation, and controlling the presence of DHA in our body, especially in our liver and brain, which is crucial for optimal brain functionality. Considering that DHA is the principal omega-3 FA in cortical gray matter, the importance of DHA intake and its derived lipid mediators have been recently reported in patients with major depressive and bipolar disorders, Alzheimer disease, Parkinson’s disease, and amyotrophic lateral sclerosis. The present study reviews the relationships between major diseases occurring today in the Western world and LC-PUFAs. More specifically this review focuses on the dietary omega-3 LC-PUFAs and the omega-6/omega-3 balance, in a wide range of inflammation disorders, including autoimmune diseases. This review suggests that the current recommendations of consumption and/or supplementation of omega-3 FAs are specific to particular groups of age and physiological status, and still need more fine tuning for overall human health and well being.

title: Introduction: The Role of Fats in Human Diet
abstract: This chapter reviews the role of fat in human diets. The term lipid is used to describe fatty acids and esters and potential esters of fatty acids. Most dietary fat consist of triglycerides, but there are small amounts of more complex lipids, such as phospholipids, present in the cell membranes of all food we eat. For many years, fat has been regarded as an undesirable constituent of the human diet, contributing to obesity, type 2 diabetes, cardiovascular disease, and cancer. However, more recently, this dogma has been questioned by findings from long-term prospective cohort studies, which have measured individual intakes and related intake to subsequent risk of disease with adjustment for differences in known risk factors, such as smoking, low socioeconomic status, age, and gender. Furthermore, there is a growing evidence to suggest that the replacement of fat by refined carbohydrates may have adverse health effects and that some lipids (e.g., the essential fatty acids) and constituents of vegetable oils, such as vitamin E, phytosterols, and polyphenols, have positive health effects. However, the key dietary role of fat is to supply food energy. It also provides the essential fatty acids and facilitates the absorption of fat-soluble vitamins (A, D, E, and K). Fat is also an important functional ingredient, acting as a carrier of flavors, as well providing desirable textures and mouthfeel to many food products.

title: Fatty Acids: Structures and Properties
abstract: Fatty acids play a key role in metabolism: as a metabolic fuel, as a necessary component of all membranes, and as a gene regulator. In addition, fatty acids have a number of industrial uses. 
 
 
 
 
biological effects; 
eicosanoids; 
requirements; 
polyunsaturated fatty acids; 
diet; 
peroxidation

title: Cyclopropane ring formation in membrane lipids of bacteria.
abstract: It has been known for several decades that cyclopropane fatty acids (CFAs) occur in the phospholipids of many species of bacteria. CFAs are formed by the addition of a methylene group, derived from the methyl group of S-adenosylmethionine, across the carbon-carbon double bond of unsaturated fatty acids (UFAs). The C1 transfer does not involve free fatty acids or intermediates of phospholipid biosynthesis but, rather, mature phospholipid molecules already incorporated into membrane bilayers. Furthermore, CFAs are typically produced at the onset of the stationary phase in bacterial cultures. CFA formation can thus be considered a conditional, postsynthetic modification of bacterial membrane lipid bilayers. This modification is noteworthy in several respects. It is catalyzed by a soluble enzyme, although one of the substrates, the UFA double bond, is normally sequestered deep within the hydrophobic interior of the phospholipid bilayer. The enzyme, CFA synthase, discriminates between phospholipid vesicles containing only saturated fatty acids and those containing UFAs; it exhibits no affinity for vesicles of the former composition. These and other properties imply that topologically novel protein-lipid interactions occur in the biosynthesis of CFAs. The timing and extent of the UFA-to-CFA conversion in batch cultures and the widespread distribution of CFA synthesis among bacteria would seem to suggest an important physiological role for this phenomenon, yet its rationale remains unclear despite experimental tests of a variety of hypotheses. Manipulation of the CFA synthase of Escherichia coli by genetic methods has nevertheless provided valuable insight into the physiology of CFA formation. It has identified the CFA synthase gene as one of several rpoS-regulated genes of E. coli and has provided for the construction of strains in which proposed cellular functions of CFAs can be properly evaluated. Cloning and manipulation of the CFA synthase structural gene have also enabled this novel but extremely unstable enzyme to be purified and analyzed in molecular terms and have led to the identification of mechanistically related enzymes in clinically important bacterial pathogens.

title: Iso- and anteiso-fatty acids in bacteria: biosynthesis, function, and taxonomic significance.
abstract: Branched-chain fatty acids of the iso and anteiso series occur in many bacteria as the major acyl constituents of membrane lipids. In addition, omega-cyclohexyl and omega-cycloheptyl fatty acids are present in several bacterial species. These two types of fatty acids are synthesized by the repeated condensation of malonyl coenzyme A with one of the branched-chain and cyclic primers by the same enzyme system. The pathway of de novo branched-chain fatty acid synthesis differs only in initial steps of synthesis from that of the common straight-chain fatty acid (palmitic acid) present in most organisms. The cell membranes composed largely of iso-, anteiso-, and omega-alicyclic acids support growth of bacteria, which inhabit normal as well as extreme environments. The occurrence of these types of fatty acids as major cellular fatty acids is an important criterion used to aid identification and classification of bacteria.

title: Fatty acids as biocompounds: their role in human metabolism, health and disease--a review. Part 1: classification, dietary sources and biological functions.
abstract: Fatty acids are substantial components of lipids and cell membranes in the form of phospholipids. This review consists of two parts. The present part aims at describing fatty acid classification, dietary sources and biological functions. The second part will focus on fatty acid physiological roles and applications in human health and disease.



In humans, not all fatty acids can be produced endogenously due to the absence of certain desaturases. Thus, specific fatty acids termed essential (linoleic, alpha-linolenic) need to be taken from the diet. Other fatty acids whose synthesis depends on essential fatty acid intake include eicosapentaenoic acid and docosahexaenoic acid, found in oily fish. Dietary sources of saturated fatty acids are animal products (butter, lard) and tropical plant oils (coconut, palm), whereas sources of unsaturated fatty acids are vegetable oils (such as olive, sunflower, and soybean oils) and marine products (algae and fish oils). Saturated fatty acids have been related to adverse health effects, whereas unsaturated fatty acids, especially monounsaturated and n-3 polyunsaturated, are thought to be protective. In addition, trans fatty acids have been shown to have negative effects on health, whereas conjugated fatty acids might be beneficial. Lastly, fatty acids are the main components of lipid classes (triacylglycerols, phospholipids, cholesteryl esters, non-esterified fatty acids).



Fatty acids are important biocompounds which take part in complex metabolic pathways, thus having major biological roles. They are obtained from various dietary sources which determine the type of fat consumed and consequently health outcome.

title: Carbocyclic fatty acids in plants: Biochemical and molecular genetic characterization of cyclopropane fatty acid synthesis of Sterculia foetida
abstract: Fatty acids containing three-member carbocyclic rings are found in bacteria and plants. Bacteria synthesize cyclopropane fatty acids (CPA-FAs) only by the addition of a methylene group from S-adenosylmethionine to the cis-double bond of monoenoic phospholipid-bound fatty acids. In plants CPA-FAs are usually minor components with cyclopropene fatty acids (CPE-FAs) more abundant. Sterculia foetida seed oil contains 65–78% CPE-FAs, principally sterculic acid. To address carbocyclic fatty acid synthesis in plants, a cDNA library was constructed from developing seeds during the period of maximum oil deposition. About 0.4% of 5,300 expressed sequence tags were derived from one gene, which shared similarities to the bacterial CPA-FA synthase. However, the predicted protein is twice as large as the bacterial homolog and represents a fusion of an FAD-containing oxidase at the N terminus and a methyltransferase at the C terminus. Functional analysis of the isolated full-length cDNA was conducted in tobacco suspension cells where its expression resulted in the accumulation of up to 6.2% dihydrosterculate of total fatty acids. In addition, the dihydrosterculate was specifically labeled by [methyl-14C]methionine and by [14C]oleic acid in the transgenic tobacco cells. In in vitro assay of S. foetida seed extracts, S-adenosylmethionine served as a methylene donor for the synthesis of dihydrosterculate from oleate. Dihydrosterculate accumulated largely in phosphatidylcholine in both systems. Together, a CPA-FA synthase was identified from S. foetida, and the pathway in higher plants that produce carbocyclic fatty acids was defined as by transfer of C1 units, most likely from S-adenosylmethionine to oleate.

title: Cyclopropyl and ω-cyclohexyl fatty acids as quality markers of cow milk and cheese.
abstract: Content of cyclopropyl and ω-cyclohexyl fatty acids of microbial origin, respectively, from silage and rumen, was determined by GC-MS and confirmed by (1)H NMR in more than 200 milk samples from dairy cows fed with different forages. Cyclopropyl fatty acids (about 0.1% of milk fat) were detected for the first time in milk and they were present only in milk samples from cows fed with forages containing maize silage, which is not allowed to produce milk for some PDO cheeses as Parmigiano-Reggiano. Their determination can be proposed as a quality parameter of milk or feed and it can be useful especially to distinguish cheeses sold as Parmigiano Reggiano from others cheeses. The content of ω-cyclohexyl tridecanoic acid varied from 0.0% to 0.15% of milk fat, and it was higher in milk samples from cows fed with diets richer in cereal meals.

title: An overview on the presence of cyclopropane fatty acids in milk and dairy products.
abstract: A survey was carried out to determine the presence of cyclopropane fatty acids (CPFA) in various dairy products. CPFA such as lactobacillic acid and dihydrosterculic acid are components of bacterial membranes and have been recently detected in milk from cows fed with maize silage. In this paper about 200 dairy samples comprising cow, sheep, and goat milk, cheese, yogurt/fermented milk, and butter were analyzed. Results showed that cow milks were generally positive to CPFA (0.014-0.105% of total fatty acids), while goat, yak, and sheep milks were negative. Experimental yogurt and fermented milks showed the same CPFA content of the starting milk. Positive to CPFA were also the majority of samples of commercial butter and cheeses, except some PDO cheeses as Parmigiano-Reggiano and Fontina, cheeses from mountain regions, and goat and sheep cheeses. These data suggest that the presence of CPFA in dairy products could be used as a marker of silage feeding.

title: In vitro digestibility of cyclopropane fatty acids in Grana Padano cheese: A study combining 1 H NMR and GC-MS techniques
abstract: Cyclopropane fatty acids (CPFA), like dihydrosterculic and lactobacillic acid, are unusual fatty acids found in microorganisms, seed oils of some sub-tropical plants, and protozoa. Recently, these molecules were detected in milk and dairy products, as well as in meat and fish. To the best of our knowledge, only a few studies have documented their presence and relevance in animals and humans. In the present work, the digestibility of CPFA from Grana Padano cheese was evaluated through an in vitro digestion model. Two different complementary analytical techniques (1HNMR and GC-MS) were applied for better evaluating the presence of CPFA in raw and digested matrices. Results showed that CPFA were released from tri-O-acylglycerols, and that the cyclopropane ring was not degraded, indicating their stability and potential bioaccessibility after digestion in the present model. 1H NMR and GC-MS analysis of the digested samples also provided comprehensive and complementary information for studying qualitatively and quantitatively the hydrolysis level of these fatty acids in complex lipid matrices.

title: The chemical nature of the fatty acids of Lactobacillus arabinosus.
abstract: The fundamental observation (2-7), that a number of biotin-requiring lactobacilli grow normally in the absence of this growth factor when they are supplied with certain fatty acids, prompted an inquiry into the chemical nature of the fatty acids of a number of these organisms. These investigations will contribute to a better understanding of fatty acid metabolism of microorganisms and, in addition, might offer important clues on the metabolic r81e of biotin. Investigations on the nutritional requirements of microorganisms have led to the discovery of a number of vitamins. A similar development, with regard to fatty acids may be envisioned, since the isolation from microorganisms of as yet unrecognized fatty acids may lead to their ultimate recognition in animal tissues. This communication presents the results of a study on the chemical nature of the fatty acids of Lactobacillus arabinosus. A large quantity of this organism was grown on a semisynthetic medium, and the lipides of the harvested and washed cells were separated into two major groups, designated as “free” and “bound” lipides. The “free” lipides consisted of the acetone-ether-soluble constituents of the bacteria, while the “bound” lipides contained those substances which became ethersoluble following acid hydrolysis of the defatted cells. No attempts were made to establish the nature of the combination in which the fatty acids existed in these fractions. The crude “bound” lipides were saponified and the resulting products divided into a saponifiable and a non-saponifiable fraction. The fatty acids in the form of their methyl esters were then separated by fractional distillation in a highly efficient fractionating column of the spinning band type. Essentially three fractions were thus obtained, corresponding in their boiling points to methyl esters of acids containing 16, 18, and 19

title: Cyclopropane fatty acid metabolism: Physical and chemical identification of propane ring metabolic products in the adipose tissue
abstract: Twelve male weanling rats were distributed equally into 3 groups and placed on fat-free diets. The diets of groups 1 and 2 were supplemented with 0.54% of recemic methylcis-9,10-methylene octadecanoate (CMO) and racemic methyltrans-9,10-methylene octadecanoate (TMO), respectively. Group 3 served as a control. Gas liquid chromatography (GLC) analyses of the adipose tissue methyl esters indicated at the level fed, that cyclopropane fatty acids do not affect normal fatty acid metabolism as has been shown for cyclopropene fatty acids. GLC analyses of groups 1 and 2 revealed the presence of a different unidentified fatty acid for each of the acids fed in addition to the CMO and TMO acids themselves. Each of the unidentified acids and the CMO and TMO acids were isolated and purified by preparative GLC. The absolute identity of the CMO and TMO acids fed and isolated from body fat was established by IR, NMR, and mass spectra. The biodegradation products of the CMO and TMO esters were shown to becis- andtrans-3,4-methylene dodecanoic acid, respectively. Unequivocal proof of structure was established through synthesis followed by comparison of IR, NMR, and mass spectra and melting points, GLC retention times, and elemental analyses with those obtained for the degradation products. Neither member of the racemic mixtures of either thecis or thetrans cyclopropane acids was preferentially utilized by the rat as shown by the lack of octical activity in the degradation products and the CMO and TMO acids isolated from the body fat. The accumulations of the 3,4-methylene dodecanoic acids in the adipose tissue of the rats fed CMO and TMO cyclopropane fatty acids suggest the inability of the beta oxidation enzyme system to proceed past the cyclopropane ring in a fatty acid chain. The synthesis ofcis- andtrans-3-dodecenoic acids, intermediates in the synthesis of the 3,4-methylene dodecanoic acids, and the geometrical cyclopropane isomers are discussed.

title: Evaluation of a methylation procedure to determine cyclopropenoids fatty acids from Sterculia striata St. Hil. Et Nauds seed oil.
abstract: Cyclopropenoids fatty acids (CPFA) from Sterculia striata seed oil were characterized by gas chromatography/mass spectrometry (GC/MS) and quantified by gas chromatography-flame ionization detector (GC-FID) after derivation to fatty acid methyl esters using a cold base-catalyzed procedure. 1H nuclear magnetic resonance (NMR) analysis were done in oil and fatty acid methyl esters derivatives to quantify CPFA and verify artifacts formation during the base-catalyzed reaction. Similar quantities of CPFA were found in S. striata and Sterculia foetida seed oils before and after a base-catalyzed methylation by NMR analysis, with no artifact formation. These results were compatible with those obtained by GC-FID analysis. Transmethylation with KOH in methanol was an appropriated method to prepare cyclopropenoids fatty acids methyl esters and quantify them by GC and NMR analysis.

title: Cyclopropane fatty acid synthesis affects cell shape and acid resistance in Leishmania mexicana.
abstract: Cyclopropane fatty acid synthase (CFAS) catalyzes the transfer of a methylene group from S-adenosyl methionine to an unsaturated fatty acid, generating a cyclopropane fatty acid (CFA). The gene encoding CFAS is present in many bacteria and several Leishmania spp. including Leishmania mexicana, Leishmania infantum and Leishmania braziliensis. In this study, we characterised the CFAS-null and -overexpression mutants in L. mexicana, the causative agent for cutaneous leishmaniasis in Mexico and central America. Our data indicate that L. mexicana CFAS modifies the fatty acid chain of plasmenylethanolamine (PME), the dominant class of ethanolamine glycerophospholipids in Leishmania, generating CFA-PME. While the endogenous level of CFA-PME is extremely low in wild type L. mexicana, overexpression of CFAS results in a significant increase. CFAS-null mutants (cfas-) exhibit altered cell shape, increased sensitivity to acidic pH, and aberrant growth in serum-free media. In addition, the CFAS protein is preferentially expressed during the proliferative stage of L. mexicana and is required for the cell membrane targeting of lipophosphoglycan. Finally, the maturation and localization of CFAS protein are dependent upon the downstream sequence of the CFAS coding region. Without the downstream sequence, the mis-localised CFAS protein cannot fully rescue the defects of cfas-. Our data suggest that CFA modification of phospholipids can significantly affect the parasite's response to certain adverse conditions. These findings are distinct from the roles of CFAS in L. infantum, highlighting the functional divergence in lipid modification among Leishmania spp.

title: Fatty acid composition of seed oils from sixAdansonia species with particular reference to cyclopropane and cyclopropene acids
abstract: The oil content of sixAdansonia species (Bombacaceae family) of Madagascar (Adansonia grandidieri, A. za, A. digitata, A. fony, A. madagascariensis andA. suarenzensis) and Africa (A. digitata) ranges from 8 to 46%. All the oils give a positive response to the Halphen test. Malvalic, sterculic and dihydrosterculic acids were detected using gas liquid chromatography-mass spectrometry (GLC-MS). Epoxy or hydroxy fatty acids were not found in these oils. Fatty acid composition was determined by GLC using glass capillary columns coated with BDS and Carbowax 20 M. Results obtained for cyclopropenic fatty acids (CPEFA) were compared to those given by glass capillary GLC after derivatization with silver nitrate in methanol, by hydrogen bromide titration and by proton magnetic resonance (PMR). Good agreement was observed for the results given by the various methods. Malvalic acid content ranges from 3 to 28%, sterculic acid from 1 to 8% and dihydrosterculic acid from 1.5 to 5.1%. Odd-numbered fatty acids (Pentadecanoic and hepatadecanoic) were also observed in minute amounts (0.1–1.1%). Among the normal fatty acids, we observed mainly palmitic (21–46%), oleic (15–40%) and linoleic (12–32%). The relationship between fatty acid composition andAdansonia species is discussed.

title: Cyclopropanoic fatty acids of litchi (Litchi chinensis) seed oil. A reinvestigation
abstract: Semisynthetic cyclopropanoic fatty acids (CPFA), cis-9,10-methyleneheradecanoic acid, cis-7,8-methylenehexadecanoic acid, and dihydrosterculic acid, were obtained from the corresponding olefinic acids. Their chromatographic equivalent chain lengths on two liquid phases, together with the mass spectral data of the methoxy derivatives, were compared to the CPFA methoxy derivatives isolated from the lipid content of litchi seeds. The fatty acid composition of the litchi seed lipids included palmitic acid, oleic acid, linoleic acid, and CPFA

title: The cyclopropane fatty acid of trypanosomatids.
abstract: Cis-9,10-Methyleneoctadecanoic acid, one of a group of cyclopropane fatty acids commonly found in bacteria but not in eukaryotic cells, has been identified in the phosphatidylethanolamines of 27 isolates representing 5 genera of trypanosomatid flagellates (Crithidia, Leptomonas, Herpetomonas, Phytomonas, Leishmania). Its presence did not appear to be associated with endosymbiotic or other microbiol associates. It was absent from 12 isolates of the genera Blastocrithidia, Endotrypanum and Trypanosoma.

title: Isolation of C11 Compounds and a Cyclopropane Fatty Acid from an Okinawan Ascidian, Diplosoma sp.
abstract: Pentylphenols 1 and 2, cyclopropane fatty acid 3, and cyclopentenones 4 and 5, were isolated from an ascidian, Diplosoma sp. The structures of 1−5 were determined by spectroscopic analysis and/or synthesis. Compound 1 inhibited the division of fertilized sea urchin eggs and compound 4 showed mild cytotoxity against HCT116 cells (human colorectal cancer cell).

title: The growth phase‐dependent synthesis of cyclopropane fatty acids in Escherichia coli is the result of an RpoS(KatF)‐dependent promoter plus enzyme instability
abstract: The formation of cyclopropane fatty acids (CFAs) in Escherichia coli is a post‐synthetic modification of the phospholipid bilayer that occurs predominantly as cultures enter the stationary phase of growth. The mechanism of this growth phase‐dependent regulation of CFA synthesis was unclear, since log‐phase and stationary‐phase cultures had been reported to contain similar levels of the enzyme catalysing the reaction (CFA synthase). We report that the timing of CFA synthesis can be explained by two unusual features. First, the gene encoding CFA synthase (cfa) was found to be transcribed from two promoters and the 5′ ends of both transcripts were mapped by primer extension. One of the promoters was active only during the log‐to‐stationary phase transition and depended on the putative sigma factor encoded by the rpoS(katF) gene whereas the other promoter had a standard σ70 promoter consensus sequence and was expressed throughout the growth curve. Second, CFA synthase activity was shown to be unstable in vivo and a Cfa fusion protein was found to have a half life of <5min. The combination of these factors meant that, although CFA synthase was synthesized throughout the growth curve, a large increase in activity occurred during the log‐to‐stationary phase transition. As stationary phase progressed, the Increased CFA synthase activity rapidly declined to the basal level. This transient increase In CFA synthase activity coupled with the cessation of net phospholipid synthesis in stationary phase provides an explanation for the unusual time course of CFA synthesis.

title: Biochemistry of lipids, lipoproteins and membranes
abstract: Biochemistry of Lipids: Lipoproteins and Membranes, Volume Six, contains concise chapters that cover a wide spectrum of topics in the field of lipid biochemistry and cell biology. It provides an important bridge between broad-based biochemistry textbooks and more technical research publications, offering cohesive, foundational information. It is a valuable tool for advanced graduate students and researchers who are interested in exploring lipid biology in more detail, and includes overviews of lipid biology in both prokaryotes and eukaryotes, while also providing fundamental background on the subsequent descriptions of fatty acid synthesis, desaturation and elongation, and the pathways that lead the synthesis of complex phospholipids, sphingolipids, and their structural variants. Also covered are sections on how bioactive lipids are involved in cell signaling with an emphasis on disease implications and pathological consequences.  Serves as a general reference book for scientists studying lipids, lipoproteins and membranes and as an advanced and up-to-date textbook for teachers and students who are familiar with the basic concepts of lipid biochemistry* References from current literature will be included in each chapter to facilitate more in-depth study* Key concepts are supported by figures and models to improve reader understanding* Chapters provide historical perspective and current analysis of each topic

title: Acid habituation of Escherichia coli and the potential role of cyclopropane fatty acids in low pH tolerance.
abstract: A reversible adaptive tolerance to low pH termed 'acid habituation' is demonstrated for five strains of Escherichia coli. Superimposed upon the intrinsic acid tolerance of individual strains, acid habituation significantly enhances the survival of exponential phase cultures exposed to a lethal acid challenge (pH 3.0), and minimises inter-strain variability in acid tolerance. The fatty acid composition of acid habituated, non-habituated, and de-habituated exponential phase cultures is also reported. During acid habituation, monounsaturated fatty acids (16:1 omega 7c and 18:1 omega 7c) present in the phospholipids of E. coli are either converted to their cyclopropane derivatives (cy17:0 and cy19:0), or replaced by saturated fatty acids. The acid tolerance of individual strains of E. coli appears to be correlated with membrane cyclopropane fatty acid content and, thus, it is postulated that increased levels of cyclopropane fatty acids may enhance the survival of microbial cells exposed to low pH. The results presented illustrate the remarkable capacity of E. coli to adapt to environmental challenges, and have significant implications for the survival of spoilage and pathogenic bacteria, and hence for food safety.

title: A ring to rule them all: the effect of cyclopropane Fatty acids on the fluidity of lipid bilayers.
abstract: Cyclopropane fatty acids are widespread in bacteria. As their concentration increases on exposure to hostile environments, they have been proposed to protect membranes. Here, the effect of cyclopropane and unsaturated fatty acids, both in cis and trans configurations, on the packing, order, and fluidity of lipid bilayers is explored using molecular dynamics simulations. It is shown that cyclopropane fatty acids disrupt lipid packing, favor the occurrence of gauche defects in the chains, and increase the lipid lateral diffusion, suggesting that they enhance fluidity. At the same time, they generally induce a greater degree of order than unsaturated fatty acids of the same configuration and limit the rotation about the bonds surrounding the cyclopropane ring. This indicates that cyclopropane fatty acids may fulfill a dual function: stabilizing membranes against adverse conditions while simultaneously promoting their fluidity. Marked differences in the effect of cis- and trans-monocyclopropanated fatty acids were also observed, suggesting that they may play alternative roles in membranes.

title: Increased Serum Level of Cyclopropaneoctanoic Acid 2-Hexyl in Patients with Hypertriglyceridemia-Related Disorders
abstract: We recently reported the presence of various cyclopropane fatty acids—among them, cyclopropaneoctanoic acid 2-hexyl—in the adipose tissue of obese women. The aim of this study was to verify whether the presence of cyclopropaneoctanoic acid 2-hexyl in human serum was associated with obesity or chronic kidney disease (both being related to dyslipidemia), and to find potential associations between the serum level of this compound and specific markers of the these conditions. The serum concentration of cyclopropaneoctanoic acid 2-hexyl was determined by gas chromatography–mass spectrometry (GC–MS) in non-obese controls, obese patients, obese patients after a 3-month low-calorie diet, and individuals with chronic kidney disease. Obese patients and those with chronic kidney disease presented with higher serum levels of cyclopropaneoctanoic acid 2-hexyl than controls. Switching obese individuals to a low-calorie (low-lipid) diet resulted in a reduction in this fatty acid concentration to the level observed in controls. Cyclopropaneoctanoic acid 2-hexyl was also found in foods derived from animal fat. Serum concentrations of triacylglycerols in the analyzed groups followed a pattern similar to that for serum cyclopropaneoctanoic acid 2-hexyl, and these variables were positively correlated with each other among the studied groups. Patients with hypertriglyceridemia-related conditions presented with elevated serum levels of cyclopropaneoctanoic acid 2-hexyl. Our findings suggest that its high serum level is related to high serum triacylglycerol concentrations rather than to body mass or BMI.

title: Influence of cyclopropane fatty acids on heat, high pressure, acid and oxidative resistance in Escherichia coli.
abstract: Heat and high pressure resistant strains of Escherichia coli are a challenge to food safety. This study investigated effects of cyclopropane fatty acids (CFAs) on stress tolerance in the heat- and pressure-resistant strain E. coli AW1.7 and the sensitive strain E. coli MG1655. The role of CFAs was explored by disruption of cfa coding for CFA synthase with an in-frame, unmarked deletion method. Both wild-type strains consumed all the unsaturated fatty acids (C16:1 and C18:1) that were mostly converted to CFAs and a low proportion to saturated fatty acid (C16:0). Moreover, E. coli AW1.7 contained a higher proportion of membrane C19:0 cyclopropane fatty acid than E. coli MG1655 (P<0.05). The Δcfa mutant strains did not produce CFAs, and the corresponding substrates C16:1 and C18:1 accumulated in membrane lipids. The deletion of cfa did not alter resistance to H2O2 but increased the lethality of heat, high pressure and acid treatments in E. coli AW1.7, and E. coli MG1655. E. coli AW1.7 and its Δcfa mutant were more resistant to pressure and heat but less resistant to acid stress than E. coli MG1655. Heat resistance of wild-type strains and their Δcfa mutant was also assessed in beef patties grilled to an internal temperature of 71 °C. After treatment, cell counts of wild type strains were higher than those of the Δcfa mutant strains. In conclusion, CFA synthesis in E. coli increases heat, high pressure and acid resistance, and increases heat resistance in food. This knowledge on mechanisms of stress resistance will facilitate the design of intervention methods for improved pathogen control in food production.

title: Trans-cyclopropanation of mycolic acids on trehalose dimycolate suppresses Mycobacterium tuberculosis -induced inflammation and virulence.
abstract: Recent studies have shown that fine structural modifications of Mycobacterium tuberculosis cell envelope lipids mediate host cell immune activation during infection. One such alteration in lipid structure is cis-cyclopropane modification of the mycolic acids on trehalose dimycolate (TDM) mediated by proximal cyclopropane synthase of alpha mycolates (pcaA), a proinflammatory lipid modification during early infection. Here we examine the pathogenetic role and immunomodulatory function of mycolic acid cyclopropane stereochemistry by characterizing an M. tuberculosis cyclopropane-mycolic acid synthase 2 (cmaA2) null mutant (Delta cmaA2) that lacks trans-cyclopropanation of mycolic acids. Although titers of WT and Delta cmaA2 organisms were identical during mouse infection, Delta cmaA2 bacteria were hypervirulent while inducing larger granulomas than WT M. tuberculosis. The hypervirulence of the Delta cmaA2 strain depended on host TNF-alpha and IFN-gamma. Loss of trans-cyclopropanation enhanced M. tuberculosis-induced macrophage inflammatory responses, a phenotype that was transferable with petroleum ether extractable lipids. Finally, purified TDM lacking trans-cyclopropane rings was 5-fold more potent in stimulating macrophages. These results establish cmaA2-dependent trans-cyclopropanation of TDM as a suppressor of M. tuberculosis-induced inflammation and virulence. In addition, cyclopropane stereochemistries on mycolic acids interact directly with host cells to both positively and negatively influence host innate immune activation.

title: Recent advances in silage microbiology
abstract: Recent advances in silage microbiology are reviewed. Most new techniques in silage microbiology use the polymerase chain reaction (PCR) to make copies of a portion of the DNA in microorganisms. These techniques allow us to identify and quantify species as well as do community analysis. The PCR-based techniques are uncovering new species, both bacteria and fungi, during storage and feeding. Silage inoculants are widely available, but of greater interest has been research investigating why inoculants are so successful. Various inoculant strains have been found to produce bacteriocins and other compounds that inhibit other bacteria and fungi, improving their chances for success. In vitro ruminal fermentation research is showing that some inoculated silages affect rumen microorganisms, reducing methane in some cases and increasing microbial biomass production in others. Better understanding of silage microbiology will allow us to better manage silos and develop better inoculants to improve silage quality.

title: Biosynthesis of ω-alicyclic fatty acids induced by cyclic precursors and change of membrane fluidity in thermophilic bacteria Geobacillus stearothermophilus and Meiothermusruber
abstract: Two thermophilic strains belonging to Geobacillus stearothermophilus and Meiothermus ruber, which naturally do not synthesize ω-alicyclic fatty acids (ω-FAs) were cultivated with cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl carboxylic acids. Gas chromatography–mass spectrometry analysis of fatty acid methyl and picolinyl esters showed that both strains are able to synthesize ω-FAs when cultivated with the appropriate precursor. The incorporation of cyclic acids influenced the whole FA composition as well as membrane fluidity. Membrane fluidity of intact cells was studied by measuring the fluorescence polarisation of the probe l,6-diphenyl-1,3,5-hexatriene incorporated into membrane lipid bilayers. Cytoplasmic membrane became more fluid with increasing content of ω-FAs. This is caused by considerable changes in lipid packing within the membrane induced by the presence of ω-FAs not found in the natural environment of Geobacillus and Meiothermus strains.

title: The isolation and identification of 11-cyclohexylundecanoic acid from sheep perinephric fat.
abstract: Sheep perinephric fat has been found to contain 11-cyclohexylundecanoic acid to the extent of approximately 0.05% of the total weight of fatty acids.

title: Milk odd- and branched-chain fatty acids as biomarkers of rumen function—An update
abstract: The main odd- and branched-chain fatty acids (OBCFA) in milk of dairy cows are isomers of tridecanoic acid (iso C13:0), tetradecanoic acid (iso C14:0), pentadecanoic acid (C15:0, iso C15:0 and anteiso C15:0), hexadecanoic acid (iso C16:0) and heptadecanoic acid (C17:0, iso C17:0 and anteiso C17:0). OBCFA are suggested to reflect rumen function (e.g. ruminal fermentation pattern, including methane, duodenal flow of microbial protein and acidosis). This relies on their predominant origin, i.e. bacteria leaving the rumen. The OBCFA are synthesized de novo by ruminal bacteria and incorporated in their cell membrane, suggesting a direct relation with bacterial biomass. Their potential as duodenal markers to quantify bacterial protein is strengthened by their constant relation with bacterial N content over a diversity of bacterial groups. From a limited database, evidence was shown of a useful relation of milk OBCFA yield with microbial protein flow from the rumen, but more research is needed to elucidate some discrepancies under diverse dietary regimes. Further, variation in the OBCFA profile of pure strains of ruminal bacteria were reported and are, in the current review, linked with their production of metabolites. From this, it can be assumed that the rumen fermentation pattern is related to the rumen OBCFA profile, which seems consistent for milk OBCFA. The close stoichiometric relation between ruminal VFA and methane further opens perspective for the use of OBCFA profiles in milk to quantify methane emissions. OBCFA consistently contributing to the predictive models, irrespective of the modeling approach are: iso C14:0 and iso C15:0, which positively relate to acetate and methane and negatively to propionate; and C15:0 and C17:0 which show an inverse relationship. Anteiso C15:0 seemed only relevant in the prediction of butyrate proportions. As changes in the ruminal microbial population (e.g. increased dominance of Streptococcus bovis) sometimes initiate a chain of events that eventually might lead to (sub-acute) ruminal acidosis, OBCFA in milk fat are targeted as candidates for the early detection of ruminal acidosis. Increasing C17:0 + C17:1 cis-9 and decreasing iso C14:0 concentration show potential as indicators of sub-acute acidosis or were obvious before clinical symptoms of acute acidosis occurred. Collection of more experimental data is currently on-going for the development of more robust models to classify rumen health in continuous probability classes rather than discrete acidotic vs. non-acidotic cases.

title: Nutritional management for enteric methane abatement: A review
abstract: A variety of nutritional management strategies that reduce enteric methane (CH4) production are discussed. Strategies such as increasing the level of grain in the diet, inclusion of lipids and supplementation with ionophores (>24 ppm) are most likely to be implemented by farmers because there is a high probability that they reduce CH4 emissions in addition to improving production efficiency. Improved pasture management, replacing grass silage with maize silage and using legumes hold some promise for CH4 mitigation but as yet their impact is not sufficiently documented. Several new strategies including dietary supplementation with saponins and tannins, selection of yeast cultures and use of fibre-digesting enzymes may mitigate CH4, but these still require extensive research. Most of the studies on reductions in CH4 from ruminants due to diet management are short-term and focussed only on changes in enteric emissions. Future research must examine long-term sustainability of reductions in CH4 production and impacts on the entire farm greenhouse gas budget.

title: Development of a Quantitative GC-MS Method for the Detection of Cyclopropane Fatty Acids in Cheese as New Molecular Markers for Parmigiano Reggiano Authentication.
abstract: Cyclopropane fatty acids (CPFA), as lactobacillic acid and dihydrosterculic acid, are components of bacterial membranes and have been recently detected in milk and in dairy products from cows fed with corn silage. In this paper, a specific quantitative gas chromatography-mass spectrometry (GC-MS) method for the detection of CPFA in cheeses was developed, and the quality parameters of the method (limit of detection, limit of quantitation, and intralaboratory precision) were assessed. Limit of detection and quantitation of CPFA were, respectively, 60 and 200 mg/kg of cheese fat, and the intralaboratory precision, determined on three concentration levels, satisfied the Horwitz equation. This method was applied to 304 samples of PDO cheeses of certified origin, including Parmigiano Reggiano (Italy), Grana Padano (Italy), Fontina (Italy), Comté (France), and Gruyère (Switzerland). Results showed that CPFA were absent in all of the cheeses whose Production Specification Rules expressly forbid the use of silages (Parmigiano Reggiano, Fontina, Comté, and Gruyère). CPFA were instead present in variable concentrations (300-830 mg/kg of fat) in all of the samples of Grana Padano cheese (silages admitted). A mix of grated Parmigiano Reggiano and Grana Padano was also prepared, showing that the method is able to detect the counterfeiting of Parmigiano Reggiano with other cheeses up to 10-20% Grana Padano content. These results support the hypothesis that CPFA can be used as a marker of silage feedings for cheeses, and the data reported can be considered a first attempt to create a database for CPFA presence in PDO cheeses.

title: An Essential Gene for Fruiting Body Initiation in the Basidiomycete Coprinopsis cinerea Is Homologous to Bacterial Cyclopropane Fatty Acid Synthase Genes
abstract: The self-compatible Coprinopsis cinerea homokaryon AmutBmut produces fruiting bodies without prior mating to another strain. Early stages of fruiting body development include the dark-dependent formation of primary hyphal knots and their light-induced transition to the more compact secondary hyphal knots. The AmutBmut UV mutant 6-031 forms primary hyphal knots, but development arrests at the transition state by a recessive defect in the cfs1 gene, isolated from a cosmid library by mutant complementation. A normal primordia phenotype was achieved when cfs1+ was embedded at both sides in at least 4.0 kb of native flanking DNA. Truncations of the flanking DNA lead to reduction in transformation frequencies and faults in primordia tissue formation, suggesting that the gene is also acting at later stages of development. The cfs1 gene encodes a protein highly similar to cyclopropane fatty acid synthases, a class of enzymes shown in prokaryotes and recently in a plant to convert membrane-bound unsaturated fatty acids into cyclopropane fatty acids. In C. cinerea 6-031, the mutant cfs1 allele carries a T-to-G transversion, leading to an amino acid substitution (Y441D) in a domain suggested to be involved in the catalytic function of the protein and/or membrane interaction.

title: The Italian National Food Consumption Survey INRAN-SCAI 2005–06: main results in terms of food consumption
abstract: The current paper aims to present the main results of the Italian National Food Consumption Survey INRAN-SCAI 2005–06.  A cross-sectional study was performed. Households were randomly selected after geographical stratification of the national territory. Food consumption was assessed on three consecutive days through individual estimated dietary records.  The final study sample comprised 3323 subjects (1501 males and 1822 females) aged 0·1 to 97·7 years belonging to 1329 households: fifty-two infants (0–2·9 years), 193 children (3–9·9 years), 247 teenagers (10–17·9 years), 2313 adults (18–64·9 years) and 518 elderly (65 years and above).  Participation rate was 33 %. The mean ratio of estimated energy intake to estimated BMR was 1·41 in adults. Indicators of mean and high individual consumption are presented for fifteen large categories and fifty-one subcategories of foods and beverages, in the total population and in consumers, by age and sex categories. The overall consumption of fruit and vegetables was 418 g/d. The consumption of red meat was approximately 700 g/week, expressed as raw weight. Some specific aspects of the Italian food consumption pattern were confirmed: a large contribution from bread, pasta and pizza to cereals, from olive oil to fats and from wine to alcoholic beverages.  The database obtained from the survey will be the key reference for Italian food consumption during the coming years and will be utilized for a variety of purposes including the assessment of nutrient intakes and risk analysis.

title: A method based on 1H NMR spectral data useful to evaluate the hydrolysis level in complex lipid mixtures
abstract: A new approach is reported, based on Proton Nuclear Magnetic Resonance ( 1 H NMR) spectral data, to study qualitatively and quantitatively the hydrolysis level in complex lipid mixtures. It is based on a detailed study of the spectra of tri-, di-, mono-glycerides and fatty acids. It has been validated by using mixtures of standard compounds which simulate the complex mixtures formed in lipid digestion. To this aim the 1 H NMR spectra of pure compounds, as well as of mixtures containing different known proportions of triglycerides, 1,2-diglycerides, 1,3-diglycerides, 1-monoglycerides, 2-monoglycerides and fatty acids, were acquired. These mixtures cover a very broad range of concentrations and simulate edible oils and fats of vegetable and animal origins, including fish, with different levels of hydrolysis. Equations based on spectral data are proposed to determine the molar percentage of the different kinds of compounds that may be formed in lipid digestion, thus allowing quantification of the advance of lipolysis. To the best of our knowledge, this is the first time that a method based on 1 H NMR spectral data to quantify triglycerides, as well as partial glycerides and fatty acids in complex lipid mixtures coming from lipolysis is proposed. This methodology offers many advantages and is useful not only in the fields of food technology and nutrition, but also in others like enzymology, pharmacology, medicine and petrochemistry, among others.

title: Inhibition of ∆9-desaturase activity with sterculic acid: effect on the endogenous synthesis of cis-9 18:1 and cis-9, trans-11 18:2 in dairy sheep.
abstract: This study was conducted in lactating ewes to examine the involvement of ∆(9)-desaturase in mammary lipogenesis, especially in the endogenous synthesis of cis-9, trans-11 18:2 and cis-9 18:1, because no information on this matter was available for dairy sheep. With this aim, 6 Assaf ewes were monitored in a 15-d experiment, which included a 5-d pretreatment period, a 5-d treatment period, and a 5-d posttreatment period. During the treatment period, ewes received 0.5 g/d of sterculic acid (a cyclopropene fatty acid that inhibits ∆(9)-desaturase), delivered intravenously in 4 equal doses at 6-h intervals. Animals were fed pasture to supply mainly α-linolenic acid and minimize the amount of milk cis-9, trans-11 18:2 of ruminal origin. Sterculic acid administration was calculated to inhibit ∆(9)-desaturase by 70% based on the milk content of cis-9 14:1. This inhibition resulted in decreases in the milk content of the enzyme products (e.g., cis-9 10:1, cis-9 14:1, cis-9 16:1, cis-9 18:1, and cis-9, trans-11 18:2) and increases in its substrates (e.g., 14:0, 18:0, and trans-11 18:1), as well as in reductions in the desaturase indexes. Some other milk fatty acids, further to previously reported products or substrates of ∆(9)-desaturase (e.g., cis-15 18:1 and cis-9, cis-15 18:2, or trans-11, trans-15 18:2, and cis-9, trans-11, trans-15 18:3), were also affected by sterculic acid administration. Endogenous synthesis was the major source of cis-9 18:1 and cis-9, trans-11 18:2, accounting for 63 and 74% of its content in milk fat, respectively. To our knowledge, the present study provides the first estimates of endogenous synthesis of these 2 bioactive fatty acids in ovine milk fat.

title: Conversion of t11t13 CLA into c9t11 CLA in Caco-2 Cells and Inhibition by Sterculic Oil
abstract: Conjugated linoleic acids (CLA), and principally c9t11 CLA, are suspected to have numerous preventive properties regarding non-infectious pathologies such as inflammatory diseases, atherosclerosis and several types of cancer. C9t11 CLA is produced in the rumen during biohydrogenation of linoleic acid, but can also be synthesized in mammalian tissues from trans-vaccenic acid (C18:1 t11) through the action of delta-9 desaturase (D9D). For several years, it is also known that c9t11 CLA can be synthesized from conjugated linolenic acids (CLnA), i.e. c9t11c13 CLnA and c9t11t13 CLnA. This study aimed at investigating to which extent and by which route c9t11 CLA can be produced from another isomer of CLA, the t11t13 CLA that is structurally very similar to c9t11t13 CLnA, in Caco-2 cells.  Caco-2 cells were incubated for 24 h with 20 µmol/l of t11t13 CLA in the absence or presence of sterculic oil used as an inhibitor of D9D. Caco-2 cells were able to convert t11t13 CLA into c9t11 CLA, and c9t11t13 CLnA was formed as an intermediate compound. In the presence of sterculic oil, the production of this intermediate was decreased by 46% and the formation of c9t11 CLA was decreased by 26%. No other metabolite was detected.  These results not only highlight the conversion of t11t13 CLA into c9t11 CLA but demonstrate also that this conversion involves first a desaturation step catalysed by D9D to produce c9t11t13 CLnA and then the action of another enzyme reducing the double bond on the Δ13 position.

title: Effects of sterculic acid on stearoyl-CoA desaturase in differentiating 3T3-L1 adipocytes.
abstract: The effects of sterculic acid on cell size, adiposity, and fatty acid composition of differentiating 3T3-L1 adipocytes are correlated with stearoyl-CoA desaturase (SCD) expression (mRNA and protein levels) and enzyme activity. Fluorescence-activated cell scanning (FACS) analysis showed that adipocytes differentiated with methylisobutylxanthine, dexamethasone, and insulin (MDI) plus 100 microM sterculic acid comprised a population of predominantly large cells with reduced adiposity compared to MDI-treated cells. Although both groups had similar amounts of total fat, their fatty acid profiles were strikingly different: MDI-treated cells had high levels of the unsaturated palmitoleic (Delta(9)-16:1) and oleic (Delta(9)-18:1) acids, whereas the cells cultured with MDI plus sterculic acid accumulated palmitic (16:0) and stearic (18:0) acids together with a marked reduction in Delta(9)-16:1. Although the cells treated with MDI plus sterculic acid had similar levels of scd1 and scd2 mRNAs and antibody-detectable SCD protein as the MDI-treated cells, the SCD enzyme activity was inhibited more than 90%. The accumulation of 16:0 and 18:0, together with normal levels of fatty acid synthase (FAS) and aP2 mRNAs, shows that de novo synthesis and elongation of fatty acids, as well as cell differentiation, were not affected by sterculic acid. Because of the increase in cell size in the sterculic acid-treated cells, the insulin-stimulated 2-deoxyglucose (2-DOG) uptake was determined. Compared to MDI-treated cells, the 2-DOG uptake in the cells treated with sterculic acid was not affected. These results indicate that sterculic acid directly inhibits SCD activity, possibly by a turnover-dependent reaction, without affecting the processes required for adipocyte differentiation, scd gene expression or SCD protein translation.

title: Inhibition of Stearoyl-CoA Desaturase 1 Reduces Lipogenesis in Primary Bovine Adipocytes
abstract: The objectives were to determine the effect of stearoyl-CoA desaturase (SCD1) inhibition on adipocyte proliferation, differentiation and cellular lipid metabolism in bovine primary adipocytes. Inhibition of SCD1 activity by sterculic acid (SA) or conjugated linoleic acid, trans-10 cis-12 isomer, (t10, c12-CLA) did not alter adipocyte cellular proliferation, viability or differentiation. In 1,2-[13C]-acetate supplemented cells, the mass isotopomer distribution analysis showed that the fractional synthesis rate of [13C]-16:0 was reduced (P < 0.01) in SA and t10, c12-CLA treatments compared to control. Of the lipogenic genes, t10, c12-CLA treatment decreased (P < 0.05) the expression of SCD1, acetyl-CoA carboxylase (ACC), fatty acid synthase; whereas SA supplementation decreased (P < 0.05) the expression of ACC. Both SA and t10, c12-CLA increased (P < 0.05) the expression of hormone-sensitive lipase and carnitine palmitoyl transferase involved in lipolysis and oxidation. Inhibition of SCD1 in bovine adipocytes decreases de novo fatty acid synthesis by down-regulating genes involved in lipogenesis and up-regulating genes involved in lipolysis and oxidation.

title: Identification of Cyclopropaneoctanoic Acid 2-Hexyl in Human Adipose Tissue and Serum
abstract: Fatty acids containing a cyclopropane ring in their structure (cyclopropane FA) have been found in a wide variety of bacteria, a number of protozoa, and Myriapoda. Little is known about cyclopropane FA in mammal, especially in human tissues. The present study deals with the identification of cyclopropane FA in adipose tissue and serum of humans and rats. Fatty acids extracted from the adipose tissue and serum obtained from obese women during bariatric surgery were methylated and analyzed on GC–MS. We have identified: cyclopropaneoctanoic acid 2-hexyl, cyclopropaneoctanoic acid 2-octyl, cyclopropanenonanoic acid, and 2-[[2-[(2-ethylcyclopropyl)methyl]cyclopropyl]methyl] acid in human adipose tissue. We confirmed the presence of cyclopropaneoctanoic acid 2-hexyl by derivatization of FA extracted from human adipose tissue to picolinyl esters. Cyclopropaneoctanoic acid 2-hexyl was the main cyclopropane FA (approximately 0.4 % of total fatty acids in human adipose tissue, and about 0.2 % of total fatty acids in the serum). In adipose tissue cyclopropaneoctanoic acid 2-hexyl was found mainly in triacylglycerols, whereas in serum in phospholipids and triacylglycerols. The cyclopropaneoctanoic acid 2-hexyl has also been found in serum, and adipose tissue of rats in amounts comparable to humans. The content of cyclopropaneoctanoic acid 2-hexyl decreased in adipose tissue of rats maintained on a restricted diet for 1 month. In conclusion, we demonstrated that cyclopropaneoctanoic acid 2-hexyl is present in human adipose tissue and serum. Adipose tissue cyclopropaneoctanoic acid 2-hexyl is stored mainly in triacylglycerols and the storage of this cyclopropane FA is affected by food restriction.

title: Analytical Approaches for the Evaluation of Food Protected Designation of Origin
abstract: The state of the art analytical methodologies used to authenticate the origin and composition of foods will be presented in the frame of the protected designation of origin for European labels. The aforementioned labels guarantee the origin and good production practices in the elaboration of foods for human consumption. Target analytes and analytical procedures, together with the chemometric tools used to discriminate foods from different areas or production methods, will be presented and critically discussed. Examples of some of the most commonly evaluated foods in the scientific literature will be also included.

title: Food authentication by PCR-based methods
abstract: Food authenticity is presently a subject of great concern to food authorities, as the incorrect labelling of foodstuffs can represent a commercial fraud. The implication of misleading labelling can be much more important concerning the presence of potentially allergenic foods. The need to support food labelling has provided the development of analytical techniques for the analysis of food ingredients. In the last years, several methods based on polymerase chain reaction (PCR) have been proposed as useful means for identifying species of origin in foods, as well as food allergens and genetically modified organisms (GMO), due to their high specificity and sensitivity, as well as rapid processing time and low cost. This work intends to provide an updated and extensive overview on the PCR-based methods for food authentication, including also methods for allergens and GMO the detection in foods.

title: Implementation of Foodomics in the Food Industry
abstract: In the past few years research in food and nutrition sciences has moved from classical analytical methods to very sophisticated omics approaches that create an impressive amount of data. The latest can only be analyzed using bioinformatics tools. Work published so far has shown the power of omic technologies in the field of foodomics. Most of the studies carried out so far used one or two approaches like transcriptomics and metabolomics, and a major challenge is integrating and connecting data sets from different expression levels such as gene, transcript, protein, and metabolite. However, developments still have to be done to transfer this approach used mainly in research laboratories to the industrial world. Most of the techniques involved in foodomics approaches are complex, costly, and need highly trained people to obtain robust data. Teams working in this field must be composed of people having complementary skills in chemistry, analysis, statistics, biology, and bioinformatics. Governments of different countries have developed large “omics” centers, sometimes using joint ventures with private industries. Other private companies have invested money and provide services to laboratories of the public sector. Initiatives of sharing databases and bioinformatics tools have also been proposed. Consequently, one way to innovate in this field would be by having closer collaborations between the academic world and industry.

title: Analytical authentication of organic products: an overview of markers.
abstract: Consumers' interest in organic foods is increasing and so is the need for robust analytical tools for their authentication. This review focuses on the most promising biomarkers/analytical approaches that are available for the authentication of organic produce. Food products have been subdivided into two groups: foods of plant origin (crops) and foods of animal origin (meat, milk and dairy products, eggs and fish). For each food category the most suitable biomarkers are presented and their potential for authentication is discussed. In the light of current knowledge, it is unlikely that the authentication of organic food products can be attained by the measurement of a single marker. Analytical approaches based on the measurement of multiple markers and/or complex chemical or physical profiles/fingerprints supported by multivariate statistical analysis seem considerably more promising in this respect. For the development of robust classification models, well-designed experimental studies must be performed that rely on data sets that are both well balanced and of sufficient size to ensure that all relevant sources of variation for the target biomarkers are included in the reference database.

title: A review of the analytical methods coupled with chemometric tools for the determination of the quality and identity of dairy products
abstract: There is an increasing demand of the consumers and actors of the food industry sector to have means of measurement allowing the characterisation of raw materials or food. Dairy products (milk, ice cream, yogurt, butter, cheese, etc.) are in considerable demand, command premium prices and are, therefore, vulnerable to economic adulteration. Authenticity of these products is an important issue for food processors, retailers, regulatory authorities and consumers. It is also valuable for ensuring fair competition and as a mean of protecting consumers against fraud due to mislabelling. Conventional chemical methods are not able to determine the regional provenance of dairy products unambiguously. Therefore, alternative techniques such as spectroscopic techniques i.e., near infrared (NIR), mid infrared (MIR), front face fluorescence spectroscopy (FFFS), stable isotope and nuclear magnetic resonance (NMR)-coupled with chemometric tools have many potential advantages as tools for the evaluation of the identity of such products. This review article discusses the potential of destructive and non-destructive techniques for the determination of the quality and the authenticity of dairy products.

title: Analytical methods coupled with chemometric tools for determining the authenticity and detecting the adulteration of dairy products: A review
abstract: Authenticity of dairy products has become an urgent issue for producers, researchers, governments, consumers and so on due to the increase of falsification procedures inducing lost large of money as well as the confidence of consumers. The determination of the authenticity and the detection of adulteration of milk and dairy products have been determined by several analytical techniques (e.g., physico-chemical, sensory, chromatography, and so on). Although these methods are considered as the reference ones, they required sophisticated analytical equipment's and skilled operators; they are also time consuming and need both the purchase and disposal of chemical reagents. Therefore, there is a need to find cheap and fast methods for the determination of the authenticity and the detection of adulteration of these products. Thus, spectroscopic techniques such as fluorescence spectroscopy, near infrared (NIR), mid infrared (MIR), nuclear magnetic resonance (NMR), among others, in combination with multivariate data analysis methods could be considered helpful tools in this domain. The advantages and disadvantages of each technique will be also discussed in this review.

title: Meat Authentication via Multiple Reaction Monitoring Mass Spectrometry of Myoglobin Peptides.
abstract: A rapid multiple reaction monitoring (MRM) mass spectrometric method for the detection and relative quantitation of the adulteration of meat with that of an undeclared species is presented. Our approach uses corresponding proteins from the different species under investigation and corresponding peptides from those proteins, or CPCP. Selected peptide markers can be used for species detection. The use of ratios of MRM transition peak areas for corresponding peptides is proposed for relative quantitation. The approach is introduced by use of myoglobin from four meats: beef, pork, horse and lamb. Focusing in the present work on species identification, by use of predictive tools, we determine peptide markers that allow the identification of all four meats and detection of one meat added to another at levels of 1% (w/w). Candidate corresponding peptide pairs to be used for the relative quantification of one meat added to another have been observed. Preliminary quantitation data presented here are encouraging.

title: Effect of grass or concentrate feeding systems and rate of growth on triglyceride and phospholipid and their fatty acids in the M. longissimus thoracis of lambs.
abstract: Thirty-two male Ile-de-France lambs were used in a factorial 2×2 design to analyse the effects of feeding systems (grass outdoor, G, or concentrate and hay indoor: stall, S) and of growth rate (low, L, or high, H) on total lipids, triglyceride (TG) and phospholipid (PL) contents and their fatty acid composition in the longissimus thoracis muscle (L.T.). Contents were lower for TG (10.4 vs. 15.8 mg/100 g fresh tissue, P<0.05) and higher for PL (6.4 vs. 5.8 mg/100 g fresh tissue, P <0.05) in grass-fed lambs compared to stall-fed ones. TG of grass fed lambs displayed lower proportions of palmitic acid (C16:0), monounsaturated fatty acids (MUFAs), linoleic acid (C18:2n-6) and other (n-6) polyunsaturated fatty acids (PUFA) and higher proportions of stearic acid (C18:0), linolenic acid (C18:3n-3), cis 9, 11 trans C18:2 and trans monounsaturated fatty acids. In PL of the same lambs only lower MUFA, C18:2n-6 and (n-6) PUFA and higher C18:3n-3, (n-3) PUFA and cis 9, 11 trans C18:2 were observed. Growth rate had no effect on lipid, TG or PL contents of longissimus thoracis. However C18:0 proportions were higher in TG and lower in PL for low growth rate lambs. Low growth rate lambs had also lower cis 9, 11 trans C18:2 in TG. Thus, irrespective of growth rate, the muscle lipids characteristic of grass fed lambs fulfilled the recommended features of human food components much better than that of stall fed lambs, namely for CLA and C18:3n-3. The lower ratios of (n-6) to (n-3) PUFA displayed in grass fed lambs both in TG and in PL were also useful to discriminate all the grass fed lambs from all the stall fed animals.

title: Effect of different types of forages, animal fat or marine oils in cow’s diet on milk fat secretion and composition, especially conjugated linoleic acid (CLA) and polyunsaturated fatty acids
abstract: This review summarises the known effects of forages, animal fats or marine oils on bovine milk fat secretion and composition. Special attention is given to fatty acids that could play a positive role for human health, such as butyric acid, oleic acid, C18 to C22 polyunsaturated fatty acids and conjugated linoleic acid (CLA). The efficiency of the transfer of n-3 polyunsaturated fatty acids from diet to milk is reviewed. Milk fat from pasture fed cows seems to be higher in linolenic acid than milk fat from cows receiving preserved grass or maize, but the magnitude of this difference is limited. Indirect comparisons show that milk fat from maize silage diets is richer in short-chain FA and linoleic acid when compared to grass silage diets. Compared to fresh grass, grass silage favours myristic and palmitic acids at the expense of mono- and polyunsaturated FA, including CLA. Protected tallow allows for a large increase in milk fat yield, and in the percentage of milk stearic and oleic acids, at the expense of medium chain FA. Non-protected tallow has a similar effect on medium chain FA without increasing so much C18 FA yield, which explains that it does not increase milk fat yield. Dose–response curves of milk CLA are reviewed for marine oil supplements, as well as the relationship between milk CLA and trans-C18:1 contents. The potential of marine oil supplementation to increase the mean CLA content in cow milk fat is large (more than 300% above basal values). A specific role for dietary C20:5 n-3 in the sharp decrease in milk fat secretion after fish oil supplementation is suggested. However, there is a need to evaluate how the different feeding strategies could change the other aspects of milk fat quality, such as taste, oxidative stability or manufacturing value.

title: Species determination - Can we detect and quantify meat adulteration?
abstract: Proper labelling of meat products is important to help fair-trade, and to enable consumers to make informed choices. However, it has been shown that labelling of species, expressed as weight/weight (w/w), on meat product labels was incorrect in more than 20% of cases. Enforcement of labelling regulations requires reliable analytical methods. Analytical methods are often based on protein or DNA measurements, which are not directly comparable to labelled meat expressed as w/w. This review discusses a wide range of analytical methods with focus on their ability to quantify and their limits of detection (LOD). In particular, problems associated with a correlation from quantitative DNA based results to meat content (w/w) are discussed. The hope is to make researchers aware of the problems of expressing DNA results as meat content (w/w) in order to find better alternatives. One alternative is to express DNA results as genome/genome equivalents.