bluuebunny/crossref_metadata_2025 huggingface dataset:
Pickled soft cheese-making from recombined milk with added dried buttermilk
Authors: El-Salam Mohamed H. Abd , El-Shibiny Safinaz , Moneib Ahmed , El-Heiba A. Abo , Al-Khamy Ahmed
Published: June 2009

Pickled soft cheese was made from recombined milk (30 % total solids, 8 % fat) containing buttermilk powder (0–4%) and stored in the pickle at room temperature (25±5 °C) for 135 d. The yield, quality and composition of cheese were followed periodically during storage. The addition of buttermilk slightly increased the yield and improved the flavour intensity of the cheese, whilst only slightly affecting its chemical composition.
Isolation of κ-casein-like fractions from human whole casein by chromatography on thiol-Sepharose, hydroxyapatite and DEAE-cellulose
Authors: Chobert Jean-Marc , Addeo Francesco , Dumas Bruno Ribadeau
Published: June 2009

Different fractions of human κ-casein characterized by their sensitivity to chymosin were separated, after reduction, by affinity chromatography on thiol-Sepharose in a 0·1 m-Tris-HCl buffer, pH 7·0, containing 7 M-urea, 0·3 m-NaCl and 1 mm-EDTA. The fraction retained on the column and bearing the SH-groups was then chromatographed on hydroxyapatite in a 5 mm-phosphate buffer, pH 6·8, containing 0·2 m-KC1, 4·5 m-urea and 2 mm 2-mercaptoethanol. The fraction not retained on this column was purified by chromatography on DEAE-cellulose in a 6·6 m-urea, 0·02 m-imidazole, 0·02 m 2-mercaptoethanol buffer, pH 7·0. Two chymosinsensitive fractions were identified by starch-gel electrophoresis at pH 8·6; one of low electrophoretic mobility, the other a smeared band covering the whole distance of migration, in which several bands with mobilities greater than those of β-caseins could be detected.
Factors affecting the distribution of lipoprotein lipase activity between serum and casein micelles in bovine milk
Authors: Anderson Malcolm
Published: June 2009

The influence of mastitis and early lactation, and the effect of treating milk with heparin, blood serum and trypsin, on the proportion of lipoprotein lipase (LPL) activity in milk serum was investigated. The relative importance of milk serum LPL and LPL bound to micellar casein in promoting lipolysis was also examined. Colostrum contained LPL activity, 45% of which was found in the serum phase in samples obtained from the first milking post partum, but this value fell to 34% in samples taken 24 h later. The proportion of serum LPL was also increased in milks from quarters infected with Staphylococcus aureus, but not after overnight treatment of normal milk at 4 °C with 5% (w/v) blood serum or 2 µg/ml trypsin. The addition of 5 µg/ml heparin resulted in a consistent increase in serum LPL which varied between 14 and 50% of total milk LPL. Heparin did not release all the enzyme bound to casein micelles even after a second heparin treatment of resuspended micelles. Serum LPL was more effective in promoting lipolysis and was more responsive to blood serum activation than LPL bound to casein micelles. Lipolysis increased after heparin treatment but the increase was not related to serum LPL activity.
Triacylglycerol composition of buffalo milk fat
Authors: Arumughan C. , Narayanan K. M.
Published: June 2009

Buffalo milk fat was first separated by thin layer chromatography (t.l.c.) into high (HMT), medium (MMT) and low (LMT) molecular weight triacylglycerols. The triacylglycerol (TG) fractions thus obtained were further resolved by argentation t.l.c. into saturated,trans-monoene,cis-monoene, diene and polyene TG species. Whereas 18:1 was concentrated in HMT, 6:0, 8:0 and 10:0 tended to be located in MMT. LMT was unique in containing almost all 4:0. HMT, MMT and LMT showed great variations in their levels of different TG species. The distribution of fatty acids among the TG species was found to be characteristic of each TG species.
Effect of seasonal variation, urea addition and ultrafiltration on the heat stability of skim-milk powder
Authors: Kelly Philip M.
Published: June 2009

The heat stability of skim-milk powder varied throughout the season, but was highest during the period April–August. Addition of urea increased heat coagulation times during March–August, but the extent of increase was dependent upon urea addition either before or after preheating for 30 min at 90 °C during manufacture. During March–June, higher heat stabilities were recorded when urea was added after preheating, while in July–August urea added before preheating was more effective. Partial ultrafiltration before dehydration decreased the heat stability of reconstituted milks due to a loss of natural urea in the permeate together with a disruption in the salt balance.
Ripening changes in Cephalotyre ‘Ras’ cheese slurries
Authors: Baky Attia A. Abdel , Neshewy Ahmed El , Rabie Abdel Hamid M. , Farahat Saad M.
Published: June 2009

Cephalotyre (Ras) cheese slurries developed within 7 d of storage at 30 °C a flavour similar to that of conventional Ras cheese ripened for 2 months. Addition of a proteinase/lipase mixture, trace elements or Na citrate to fresh cheese slurries before storage at 30 °C enhanced flavour development. Additive-treated slurries showed after storage for 5 d at 30 °C a strong flavour similar to that of 3–4 months Ras cheese with increased protein degradation, acidity development, volatile fatty acid formation and higher bacterial counts. The effectiveness of the additives in enhancing flavour development and related chemical changes was in the order: proteinaseòlipase mixture > trace elements > Na citrate.
Effect of the lactoperoxidase system on lipoprotein lipase activity and lipolysis in milk
Authors: Ahrné Lennart , Björck Lennart
Published: June 2009

The lactoperoxidase/SCN-/H2O2system (LPS) was found to inhibit lipoprotein lipase (LPL) in milk. Inhibition was related to the amount of SCN-/H2O2added to milk. Lipolysis was unaltered until LPL activity was decreased to <40% of the original activity. When LPL was inhibited further, decreased lipolysis was observed. Purified LPL was also inhibited by LPS, at similar concentrations of SCN-/H2O2as in milk. It was shown that non enzymically prepared OSCN-inhibited LPL at concentrations comparable to those produced by the LPS. Cysteine could eliminate the effect of LPS on LPL. The sulphydryl reagents dithiobisnitrobenzoic acid and Na tetrathionate had no effect on LPL activity.
Interrelationships between the diet fed to cows, composition and properties of milk and composition and quality of Cheshire cheese from farmhouse manufacturers
Authors: Grandison Alistair S. , Anderson Malcolm , Ford Graeme D. , Newell Lavinia
Published: June 2009

Interrelationships between concentrations of constituents of forages in diets fed to the cows, milks and cheeses, rennet coagulation properties of milks, manufacturing methods and the grades and textural properties of the cheeses produced by four farmhouse producers of Cheshire cheese were studied during the period December 1982 to June 1983. Many intercorrelations occurred in concentrations of constituents of the milks and ultrafiltrates. Rennet coagulation properties were related to concentrations of many of the constituents of the milks and forages in the diet. Many interrelationships in parameters of cheese texture and components of cheese composition were observed. Compositions and texture of the final cheeses were generally not related to the composition of the milks used in their manufacture.
An empirical mathematical model of retentate composition in ultrafiltration of dairy products
Authors: Rham Olivier De , Chanton Serge
Published: June 2009

Analysis of retentates of milk or whey, ultrafiltered and diafiltered by a pilot batch process with DDS Lab module equipment or (whey only) ultrafiltered by an industrial continuous process showed that nitrogen and ionic contents could not be described mathematically by the use of any value of the retention coefficient K. Analytical data suggested a new concept called segregation for nitrogen and ions in which each of these components consists of a completely permeable fraction and a totally retained fraction that do not exchange. A segregation coefficient Y is then defined as the ratio of the totally retained fraction to the total concentration of the species in the product fed to the equipment. However, this concept does not apply to lactose, where the classic retention concept (K) is retained. The two models are equivalent when K = Y = 0 or K = Y = 1. A first mathematical expression of this model was elaborated for batch ultrafiltration and/or constant volume diafiltration. Another set of equations was established for industrial conditions. These empirical models predict the retentate and permeate composition at any time during processing as well as after drying. The fit of analytical data with computed values was generally fair, with K being 0·1–0·4 in the pilot plant, and 0·1 in the factory. The nitrogen Y value was ∼ 0·95 for milk, and 0·85 for whey. In whey, the calcium Y value varied greatly from 0·06–0·71 depending on the pH, citrate content and heat treatment; in milk it was fairly constant at 0·5 at pH 6·7–5·8.
Mechanisms of heat inactivation of a proteinase from Pseudomonas fluorescens biotype I
Authors: Diermayr Peter , Kroll Stefan , Klostermeyer Henning
Published: June 2009

Heat inactivation of a metalloproteinase, isolated from Pseudomonas fluorescens biotype I strain 112, was investigated in the temperature ranges 50–60 °C and 90–140 °C. At 90 °C the denaturation of the enzyme followed first-order kinetics with a decimal reduction time of 110 min and a velocity constant K of 3·5 × 10−4 s−1. Activation energy Ea was 100 kJ/mol for this temperature range. In the 50–60 °C region the proteinase was inactivated by autolysis, as shown by electrophoresis and gel filtration. At 55 °C the decimal reduction time was ∼ 22 s, at 57 °C it was 8 s. Rapid inactivation at 55 °C was only possible if the enzyme was heated from lower temperatures, but not if cooled down from 90 °C. This is due to a conformational change of the protein at this temperature. A model for the description of heat inactivation in the two temperature ranges is proposed.
Kareish cheese prepared from ultrafiltered milk
Authors: El-Zayat Ali I. , Omar Mohamed M.
Published: June 2009

Kareish cheese was made from ultrafiltered milk (UF) and standard milk and the chemical composition, organoleptic properties and microstructure of the cheese compared. Cheese made with the UF had higher moisture, protein, fat, pH, soluble N, non-protein N, amino acid N, tryptophan and free amino acids than the standard cheese. The microstructure of both types of cheese was very similar, while the organoleptic properties were more acceptable in the UF cheese.
Purification and characterization of a post-proline dipeptidyl aminopeptidase fromStreptococcus cremorisAM2
Authors: Booth Mary , Fhaoláin Ide Ni , Jennings P. Vincent , O'Cuinn Gerard
Published: June 2009

The present study describes the purification of a post-proline dipeptidyl aminopeptidase from the cytoplasm ofStreptococcus cremorisAM2. On the basis of its elution from a calibrated Sephadex G200 column, the enzyme had a molecular weight of 117000 and exhibited a broad pH optimum activity between 6·0 and 9·0. The activity was most comprehensively inhibited by phenylmethylsulphonylfluoride and more modestly inhibited by 1,10-phenanthroline and 8-hydroxyquinoline but not by EDTA. A range of peptides containing either proline or alanine as the penultimate amino acid residue could act as substrates. The presence of proline on the carboxy side of the scissile bond prevented hydrolysis. However the enzyme could release Pro-Pro from Pro-Pro-Gly-Phe-Ser-Pro. The significance of this substrate specificity is considered in the context of removal of either single proline residues or prolylproline sequences from oligopeptides during cheese ripening.
Rationale of feeding systems for lactating dairy cows
Authors: Johnson C. Lewis , Tran C. Lang
Published: June 2009

Manipulations of the lactation cycle are achieved through nutritional regimens and generally result in a restriction of the physiological lactation cycle. Most models of lactation used in management programmes only describe the average time course of lactation for groups of cows on a given feeding regimen. This is inadequate for the variety of feeding systems in use on British farms. In the present paper several existing models of lactation have been critically evaluated. An integral equation approach has been developed to rationalize experimental observations and currently accepted biological concepts.
Teat length and penetration into teatcup during milking in Norwegian Red Cattle
Authors: Rønningen Odd , Reitan Arne Dagfinn
Published: June 2009

Teat penetration into transparent silicone rubber teatcup liners was recorded during milking of 90 cows on 15 farms. The cows were of Norwegian Red Cattle breed with mean teat length close to the average for the breed. The mean teat length was 54 and 48 mm for fore and rear teats respectively, and mean penetration at the end of milking was 104 and 94 mm. No significant correlation between initial teat length and teat elongation (difference between penetration and initial length) was found. This indicated that the teatcup liner was more stable on long teats than on short. The distribution of teat penetration at the end of milking showed that a large proportion of fore teats penetrated too far into the liner at the end of milking. The optimal liner length for Norwegian Red Cattle was ~ 150 mm.
Aetiology of disturbed milk ejection in parturient primiparous cows
Authors: Bruckmaier Rupert M. , Schams Dieter , Blum Jürg W.
Published: June 2009

Milk flow in nine primiparous cows with disturbed milk ejection (D) and in six corresponding control animals (C) with normal milk removal was recorded during machine milking and blood samples were taken before and during milking to determine plasma oxytocin, vasopressin. prolactin, cortisol, oestradiol-17β, luteinizing hormone, progesterone and β-endorphin concentrations. Manual teat stimulation before milking lasted for 1 min. After milk flow had stopped, air was blown into the vagina for 2 min. When milk flow had stopped again, 1 i.u. oxytocin and finally 10 i.u. oxytocin were injected to remove residual milk. During and after teat stimulation, oxytocin remained basal in D, but increased in C, whereas prolactin increased in both groups. While 94% of total milk was obtained in C during this period, only 9% could be removed from D, indicating lack of alveolar milk ejection. During vaginal stimulation, oxytocin increased transiently in D and more than by teat stimulation in C. This allowed the removal of 75% of milk in D, whereas almost no more milk was available in C. After oxytocin injections, 3 and 16% of residual milk were obtained in C and D respectively. Basal oestradiol-17β concentration was higher in D than in C (11·6 and 2·0 ng/1 respectively), whereas β-endorphin level was lower (24·1 and 86·6 μg/1 respectively). Basal concentration of luteinizing hormone and progesterone, and concentration of cortisol and vasopressin before and during milking were comparable in C and D. We conclude that in cows with disturbed milk ejection afferent nervous pathways to the hypothalamus were intact, because prolactin was released by teat stimulation. However, oxytocin was only released by vaginal stimulation, i.e. milk ejection was centrally inhibited during teat stimulation.
Ultrafiltration with a microfiltration membrane of acid skimmed and fat-enriched milk coagula: hydrodynamic, microscopic and rheological approaches
Authors: Attia Hamadi , Bennasar Michel , Lagaude Alain , Hugodot Bernard , Rouviere Jacques , De La Fuente Blas Tarodo
Published: June 2009

The effect of acidification method (microbiological with or without renneting, HCl addition) on mass transfer, fouling structure and the rheology of the retentate was studied in the ultrafiltration of skim milk coagula using a mineral microfiltration membrane. The increase in fouling with time appeared to determine permeate flow rates, which were higher in biological coagula, and the protein retention rates which were higher in chemical coagula. Fouling was investigated using scanning electron microscopy. The rheological study showed that at the same total solids, biological coagula were more viscous than chemical coagula. The initial coagula (total solids 97 g/kg) all displayed pseudoplastic behaviour at low shear velocities and Newtonian behaviour at high velocities. Ultrafiltration of fat-enriched milk coagulum to a dry weight corresponding to a soft cheese (total solids 334 g/kg; fat in total solids 60%) gave satisfactory permeate flow rates and protein retention rates. Performance was related to the composition of the product, the hydrodynamic parameters used and the resulting fouling. The rheological study showed that the initial coagulum behaved as a pseudoplastic body at low shear rate and for higher velocities as a Newtonian liquid. The concentrated retenate behaved as an ideal viscoplastic body (Bingham body).
Numerical taxonomy of psychrotrophic bacteria isolated from raw ewes' milk
Authors: García-Armesto María-Rosario , Prieto Miguel , Alonso Carlos , GarcíLópez María-Luisa , García-Fernández María-Camino , Otero Andrés
Published: June 2009

A total of 204 psychrotrophic isolates from raw ewes' milk (hand and machine milked) were identified by conventional methods. In addition, a numerical taxonomic study was conducted on 180 of these isolates and 19 reference strains. Three of the isolates were yeasts. Using identification schemes, 54 isolates were assigned to genera of Gram-negative aerobic rods (Pseudomonas, Acinetobacter, Flavobacterium, MoraxellaandPsychrobacter), 48 were Enterobacteriaceae (Entero-bacter, Hafnia, Klebsiella, CitrobacterandSerratia) and one was identified asAeromonas hydrophila. The 98 Gram-positive isolates were identified asEnterococcus, Streptococcus, Leuconostoc, Lactococcus, Bacillus, Staphylococcus, Micrococcus, Aureobacterium, KurthiaandMicrobacterium. At the 82% similarity level (SSM), 18 clusters were formed. Cluster I included 34 strainsof Lactococcus, StreptococcusandLeuconostoc. Most of the 35 strains in cluster II wereEnterococcus. Clusters III and IV were identified asKurthiaandMicrobacteriumrespectively. Cluster V was identified asAureobacteriumand cluster VI consisted of coagulase-negative staphylococci. Gram-negative isolates formed 12 clusters:Aeromonas(one cluster), Enterobacteriaceae (two clusters),Flavobacterium(two clusters),PseudomonasandPsychrobacter immobilis(three clusters) andAcinetobacter(four clusters). Non-motile variants ofPs. fragiwere found.Enterococcusand Enterobacteriaceae did not have significant spoilage properties. As expected, Gram-negative aerobic rods were proteolytic and/or lipolytic even at low temperature. Contamination with certain types of psychrotrophs (Gram-negative aerobic rods and enterococci) seemed to be associated with the milking method. The isolate ofAes. hydrophilahad properties associated with virulence.
Effect of milk protein standardization, by ultrafiltration, on the manufacture, composition and maturation of Cheddar cheese
Authors: Guinee Timothy P. , Pudja Predrag D. , Mulholland Edward O.
Published: June 2009

Skim milks were pre-acidified to pH 6·4 and concentrated by ultra-filtration to give retentates with protein levels of 210 g/1. Retentates were blended with skim milk and cream to give standardized milks with protein levels ranging from 30 to 82 g/1. These were used for the manufacture of Cheddar cheese in conventional equipment. Increasing milk protein level resulted in reduced gelation times, increased curd firming rates and a decrease in the set-to-cut time when cutting at equal firmness values (i.e. elastic modulus, G′, ∼ 16 Pa). As the curd firming rates increased with milk protein level, it became increasingly difficult to cut the curd cleanly, without tearing, before the end of the cutting cycle. Reflecting the tearing of curd, and consequent curd particle shattering, fat losses in the running wheys were greater than those predicted on the basis of volume reduction (due to ultrafiltration) for milks with protein levels > 50 g/1. Reduction of setting temperatures, in the range 31–27 °C, and the level of added rennet brought the set-to-cut times and curd firming rates of concentrated milks closer to those of the control milk. While increasing milk protein level in the range 30–70 g/1 had little effect on cheese composition, it resulted in slower proteolysis and maturation.
Quantitation oftransfatty acids in milk fat using spectroscopic and chromatographic methods
Authors: Ulberth Franz , Henninger Monika
Published: June 2009

Transfatty acids (TFA) formed during biohydrogenation by ruminant animals were quantified in cows' milk fat by means of Fourier transform i.r. (FTIR) spectroscopy. When samples were analysed as the derived methyl esters, a spectral subtraction technique resulted in TFA values that were not biased by the unspecific absorption of intact triacylglycerols or influenced by the shape of thetransband. Austrian milk fat samples contained 20–50 g TFA/kg. Results obtained by analysis of TFA as triacylglycerols compared favourably with those obtained by using methyl esters. The findings of the FTIR method were further substantiated by applying argentation chromatography in combination with capillary gas chromatography to the same set of samples. Besidestransmonoenoic acids, non-methylene interruptedcis, transoctadecadienoic acids contributed significantly to the totaltranscontent. Two novel TFA,trans-11,cis-15 octadecadienoic andcis-9,trans-13 octadecadienoic acids, were identified in milk fat by means of their retention behaviour on argentation chromatography and gas chromatography as well as by an oxidative degradation procedure.
Changes in the microflora of La Serena ewes' milk cheese during ripening
Authors: Del Pozo Buensuceso Fernandez , Gaya Pilar , Medina Margarita , Rodríguez-Marín M. Asunción , Nuñez Manuel
Published: June 2009

The microflora of ten batches of La Serena cheese, made from raw milk of Merino ewes and using vegetable rennet as coagulant, was monitored throughout a 60 d ripening period. After 15 d, lactic acid bacteria predominated in the interior of the cheese, whilst lactic acid bacteria and lactic acid-utilizing species of yeasts and moulds predominated on the cheese surface. Coagulase-positive staphylococci were not detected in the interior or on the surface of any of the cheeses after 45 d and faecal coliforms were not found after 60 d. Higher death rates of staphylococci and coliforms were recorded for cheese made in spring than for the cheese made in winter.
Changes in chemical and rheological characteristics of La Serena ewes' milk cheese during ripening
Authors: Del Pozo Buensuceso Fernandez , Gaya Pilar , Medina Margarita , Rodríguez-Marín M. Asunción , Nuñez Manuel
Published: June 2009

Casein breakdown and free fatty acids formation were studied in ten batches of La Serena cheese throughout a 60 d ripening period. A rapid degradation of αs1-casein occurred, with only 18·6% residual αs1-casein being detected in 60 d-old cheese, whereas 49·5% β-casein remained unattacked. High pH values, low NaCl-in-moisture concentrations and high moisture contents enhanced proteolysis. Lac-tobacilli and yeasts were the only microbial groups which significantly influenced αs1-casein breakdown, and only yeasts affected β-casein hydrolysis. No significant effect of chemical characteristics or microbial groups on FFA levels was detected, an average level of 12·7 mequiv./100 g fat being recorded for 60 d cheese. Rheological characteristics of the cheese reached their minimum values after 15–30 d of ripening and were dependent on αs1- and β-casein breakdown, pH value, NaCl-in-moisture concentration and moisture content.
Biologically active peptides of casein and lactotransferrin implicated in platelet function
Authors: Fiat Anne-Marie , Levy-Toledano Sylviane , Caen Jacques P. , Jollès Pierre
Published: June 2009

Casein and other milk proteins in maternal colostrum and milk, the earliest food of the newborn, should not only be considered as a nutritional supply but also as a source of biologically active peptides. Some of them isolated from casein and lactotransferrin were active on platelet function. They inhibited both aggregation of ADP-treated platelets and binding of [125I] fibrinogen to ADP-treated platelets. Their behaviour was compared to that of fibrinogen peptides possessing similar effects: once more similarities between the milk and blood-clotting phenomena could be observed.
Automatic application of teat disinfectant through the milking machine cluster
Authors: Grindal Robert J. , Priest David J.
Published: June 2009

An automatic device, which infuses disinfectant into the mouthpiece of the liner of the milking machine cluster as teatcups are removed, is described. Application at this time avoids any delay in disinfection, reduces the workload in the parlour and increases reliability of application. The teats of 20 cows were contaminated before each milking by immersion in a suspension of Staphylococcus aureus and Streptococcus agalactiae and then disinfected manually or automatically with iodophor after milking. Str. agalactiae was recovered from < 5% of swabs and there was no difference between the results from the two methods. Neither method of disinfection was as effective against Staph. aureus and the recovery rate was significantly greater for the automatic method for both swabs from teat barrel (P < 0·05) and teat apex (P < 0·001). Rates of intramammary infection for quarters automatically or manually disinfected were similar and low (3/40 v. 6/40 respectively). The automatic method facilitates cluster removal by relieving vacuum and decreasing frictional contact at the mouthpiece lip, and utilizes approximately half the quantity of disinfectant used by manual dipping (0·9 v. 1·9 ml/teat). However, iodine contamination in the milk from the iodophor teat disinfectant was significantly increased from 14·4 to 102·2 μg I2/100 ml milk when no backflushing was practised.
Comparison of Cheddar cheese made with a recombinant calf chymosin and with standard calf rennet
Authors: Bines Valerie E. , Young Paul , Law Barry A.
Published: June 2009

The cheesemaking properties of recombinant chymosin from Kluyveromyces lactis (Gist-Brocades Chymosin 610) were Compared with those of standard rennet in parallel trials with the same milk and mixed culture starter. For each pair of cheeses the cheesemaking characteristics, mass balance results, composition of the cheeses at 6 weeks and maturation rates were similar. A taste panel was not able to differentiate between the cheeses at 3, 6 or 12 months.
Development of a cows' milk identification test (COMIT) for field use
Authors: García Teresa , Martín Rosario , Rodríguez Elena , Hernández Pablo E. , Sanz Bernabé
Published: June 2009

A cows' milk identification test (COMIT) has been successfully developed for the detection of defined amounts of cows' milk (3–100%) in ewes' milk. The assay uses polyclonal antibodies raised in goats against bovine whey proteins. The test, an agar-gel immunodiffusion technique, uses agar plates with a printed template for correct placement of the test components (antisera discs, positive and negative milk reference discs and sample discs). The presence of cows' milk in the sample was recorded as positive when the precipitin lines appearing between the sample disc and the antisera disc fuse completely with those from the positive cows' milk reference disc. This test is reliable, practical and easy to perform in the field and in dairy factories. Furthermore, the nature and stability of the components of the test make it suitable for commercial development into kits which should be highly practical in any kind of inspection programme concerned with milk species identification.
Ultraviolet spectroscopic studies on the feathering of cream in instant coffee
Authors: Hamboyan Lucie , Pink* David A. , Klapstein Dieter , MacDonald Lynn , Aboud Helen
Published: June 2009

The extent of cream feathering was observed in samples of six brands of instant coffee at 80 °C and classified on a scale of 0 (non-existent)–3 + (very severe). The hypothesis that it is caused by the amount of chlorogenic acid in the samples was tested. Ultraviolet spectra were recorded between 230 and 486 nm, and the amount of chlorogenic acid was measured from the absorbance at 340 nm. It was found that: (i) u.v. spectra of a given brand of coffee prepared at different concentrations could all be superimposed when concentration and dilution were taken into account, and the spectrum did not change between room temperature and 80 °C; (ii) for a given coffee a minimum amount of chlorogenic acid was needed to cause feathering, but that this amount differed by up to a factor of 10 depending upon the coffee; (iii) only two fundamental shapes of spectra were observed and coffees could be classified by a ratio, R, which lay between two ranges: 0·82 < R < 0·90 or 1·10 < R < 1·27; (iv) a knowledge of the chlorogenic acid content of a sample and the value of R appropriate to that coffee could be used to predict the occurrence of feathering.
Variation with season and lactation of plasmin and plasminogen concentrations in Montbeliard cows' milk
Authors: Benslimane Saloua , Dognin-Bergeret Mai J. , Berdague Jean-Louis , Gaudemer Yves
Published: June 2009

Plasmin and plasminogen were determined monthly over a one year period in samples of bulk and herd milks from Montbeliard cows. Montbeliard milk showed a high content of plasmin and plasminogen in comparison with milk from other breeds. In bulk milk, the plasmin activity reached a minimum in September (O·15 μg/ml milk) and a maximum in June (0·32 μg/ml milk). The annual mean concentration was 0·23 μg/ml milk. The plasminogen content varied around a value of 1·28 μg/ml milk, with a marked decrease in September (0·83 μg/ml milk) and a maximum in October (1·59 μg/ml milk). In herd milk, the minimum plasmin activity occurred in October (0·17 μ/ml milk) and the maximum in spring (O·42 μg/ml milk in May) with an annual mean of 0·30 μg/ml milk. The plasminogen content varied in a similar way, from 0·87 μg/ml milk to 1·82 μg/ml milk, with an annual mean of 1·46 μg/ml. The ratio plasminogen: plasmin ranged from 1·4 to 9·2 with an average of 4·9. From early to late lactation, plasmin and plasminogen concentrations increased from 0·25 to 0·38 μg/ml milk and from 1·07 to 2·01 μg/ml milk respectively and the plasminogen: plasmin ratio increased from 4·5 to 5·3. Studies of milk from cows at similar stage of lactation within a single herd have shown the necessity for distinguishing between two phases in the early stage of lactation. The first, a very early period, is usually present up to one month and the second occurs in the second and third months. Milk samples with the highest proportion of γ-caseins were not those with the greatest plasmin content but were those with high plasminogen contents, which had increased suddenly from the levels of the preceding month. This suggests a role for the plasminogen activator and inhibitor system.
Local control of the onset of mammary extraction of plasma triglycerides during lactogenesis in the goat
Authors: Thompson Gordon E.
Published: June 2009

In five untreated goats, mammary extraction of plasma triglycerides increased at parturition. In five goats that had as much secretion as possible regularly removed from one mammary gland beginning on d 143 of gestation, the change of triglyceride extraction occurred several d before parturition in the emptied gland but at parturition in the contralateral control gland. The experimentally induced early increase of extraction of plasma triglycerides preceded the increase of prostaglandin Fα concentration in mammary secretion at parturition, and occurred despite abnormally high concentrations of progesterone in the secretion.
Interactions between the bovine milk fat globule membrane and skim milk components on heating whole milk
Authors: Houlihan Avis V. , Goddard Philippa A. , Nottingham Stephen M. , Kitchen Barry J. , Masters Colin J.
Published: June 2009

Heating raw milk at 80 °C for 2·5–20 min was found to result in compositional changes in the milk fat globule membrane (MFGM). The yield of protein material increased with the duration of heating, owing to incorporation of skim milk proteins, predominantly β-lactoglobulin, into the membrane. Lipid components of the MFGM were also affected, with losses of triacylglycerols on heating.
Characterization of the 12% trichloroacetic acid-insoluble oligopeptides of Parmigiano-Reggiano cheese
Authors: Addeo Francesco , Chianese Lina , Salzano Antonio , Sacchi Raffaele , Cappuccio Ugo , Ferranti Pasquale , Malorni Antonio
Published: June 2009

The isolation and identification of low molecular mass peptides formed during the ripening of Parmigiano-Reggiano cheese is described. A strategy was used based on the fractionation of nitrogenous material using chemical methods followed by HPLC to isolate peptides and fast atom bombardment-mass spectrometry to identify them. It was found that the majority of cheese oligopeptides arose from the proteolysis of β-casein. Several phosphopeptides and oligopeptides known in vivo to be biologically active have also been identified during the ripening of cheese.
Gel electrophoresis and immunoblotting for the detection of casein proteolysis in cheese
Authors: Addeo Francesco , Garro Giuseppina , Intorcia Nunziatina , Pellegrino Luisa , Resmini Pierpaolo , Chianese Lina
Published: June 2009

The whole N fraction of six samples of hard and semi-hard pressed cheeses was analysed using PAGE, polyacrylamide gel isoelectric focusing and immuno blotting with polyclonal antibodies against β- and αs1-casein. The origin of some electrophoretic bands corresponding to peptides produced from the enzymic degradation of the casein fractions was established. A number of these peptides were also present in thein vitrohydrolysates of casein with plasmin and chymosin. Thus, it was also possible to determine which casein was the source of each peptide and which enzymes were active in cheese. Compared with the traditional Coomassie staining procedures, immunoblotting is more sensitive and specific, making the interpretation of each electrophoretic profile easy. Thus, it was also possible to obtain a clear picture of the state of each casein fraction in a cheese variety. Two main peptides were isolated from the pH 4·6-insoluble N fraction of Parmigiano-Reggiano using DEAE-cellulose chromatography and identified, from the amino acid sequence of the N- and C-terminal ends, as γ3-casein (β-casein(f108–209)) and αs1-PL1 (αs1-casein(f80–199)). In both cases, a Lys–X bond was hydrolysed, indicating the action of a trypsin-like enzyme in β- and αs1-casein hydrolysis during the ripening of this variety of hard pressed cheese.
Mordant factors that affect the fluorescence and counting of somatic cells by instruments
Authors: Clarke Timothy , Evans Michael E. , Hepworth Graham , Moate Peter J. , Stewart John A.
Published: June 2009

The requirement for accuracy in the counting of somatic cells in milk has been increased by the use of this measurement as a basis of payment for milk. This paper reports on several factors that can substantially affect efficiency of staining and cell detection in various types of fluorescent cell counters. These mordant factors include sample age, chemical preservative, other sample preservation treatments and reagent properties. Experiments were conducted in several laboratories with Fossomatic 215 and 360 cell counting instruments to measure the effect of these mordant factors on both cell fluorescence and cell count. Counting efficiency was as low as 20% for some instruments counting some particular samples, depending upon the combination of adverse mordant factors. The problem of poor counting efficiency was also not detected by calibration samples that had more favourable mordant treatments applied. The adverse mordant factors were shown to reduce the intensity of fluorescence of cells for all instruments. We suggest that a significant reduction in counting efficiency due to these adverse mordant factors is most likely to occur when the particular instrument already has an intrinsic inability to separate cell fluorescence properly from background noise. This paper also discusses quality control samples, the impact of various factors on discriminator curves and the use of appropriate measures to maintain good calibration adjustment.
Analysis and production of two exopolysaccharides fromLactococcus lactissubsp.cremorisLC330
Authors: Marshall Valerie M. , Cowie Eoin N. , Moreton Rod S.
Published: June 2009

Two polysaccharides produced concurrently byLactococcus lactissubsp.cremorisstrain LC330 have been identified. One had a high molecular mass (> 1 × 106Da) and was neutral. The second was smaller (∼ 10000 Da), charged and had a high phosphorus content. Sugar composition also differed. In chemostat culture the neutral polysaccharide was influenced by temperature and by nitrogen limitation. This polysaccharide was branched with terminal galactose moieties and contained galactose, glucose and glucosamine. The phosphopolysaccharide was more complex with glucose, rhamnose, galactose and glucosamine in an approximate ratio of 6:5:4:1.
Comparative study of methods for the isolation and purification of bovine κ-casein and its hydrolysis by chymosin
Authors: Coolbear Kate P. , Elgar David F. , Coolbear Tim , Ayers John S.
Published: June 2009

κ-Casein was purified from a single batch of whole acid casein (κ-A variant) using different methods in order to compare their merits in producing a purified material with a carbohydrate and phosphate heterogeneity representative of the whole κ-casein complement in milk. Ion-exchange methods of purification gave products of higher purity than precipitation techniques involving final purification by ethanol fractionation, but all methods resulted in κ-caseins of apparently similar heterogeneity and chemical composition. The purified κ-caseins were hydrolysed with chymosin and the derived macropeptides isolated. These were all virtually identical as determined by reversed-phase chromatography and gel electrophoresis. Some observations on chymosin hydrolysis of κ-casein were made. In addition to formation of the major para-κ-casein (Glu1–Phe105) and macropeptide (Met106–Val169), chymosin hydrolysis at pH 6·6 also resulted in two minor para-κ-caseins with N-termini corresponding to Phe18 and Ser33 of κ-casein. At pH 5·5 and 4·5 para-κ-casein was rapidly hydrolysed into at least six fragments, one of which had an N-terminus corresponding to Trp76 of κ-casein. At pH 6·6, 5·5 and 4·5 the κ-casein macropeptide was stable to chymosin, but at pH 2·3 it was hydrolysed by chymosin into fragments with N-termini corresponding to Met106, He125, Ala138, Val139, Thr145 and Glu147 of κ-casein.
Influence of pulsationless milking on teat canal keratin growth and turnover
Authors: Lacy-Hulbert S. Jane , Hillerton J. Eric , Woolford Murray W.
Published: June 2009

In two separate experiments, the effects of pulsationless milking and milking vacuum on the rate of keratin removal from the teat canal were determined. Sixteen cows were milked with or without pulsation for either a single milking or for eight milkings. Milking without pulsation removed 10% of keratin present before milking, significantly less than milking with pulsation, which removed 32%. After eight milkings (4 d) without pulsation, up to 20% more keratin had accumulated within the teat canal but the rate of keratin regeneration reduced significantly upon return to pulsation milking. In a second experiment, ten cows were milked at 45 or 55 kPa and with or without pulsation. Only the absence of pulsation significantly reduced keratin loss during milking. Keratin loss during milking appears to be controlled by liner compression rather than by the rate of milk flowing through the teat canal. Pulsationless milking may increase penetrability of the teat canal to bacteria by reducing the natural rate of keratin removal during milking and reducing the rate of keratin regeneration.
328. Experiments on the use of antioxidants in spray-dried whole-milk powder
Authors: Findlay J. D. , Smith J. A. B. , Lea C. H.
Published: June 2009

1. Of a number of substances tested for antioxidant activity in laboratory-made spray-dried milk powder, ascorbic acid and ethyl gallate proved most promising. Both of these substances materially increased the resistance of the powder to the development of tallowiness without producing any foreign flavour in the milk.

2. The actitivy of both substances has been confirmed in factory-made spray-dried powder, ethyl gallate being much the more powerful of the two. Ethyl gallate at a concentration of 0·07% increased the storage life of powder in the accelerated tests 2½–3-fold.

3. Ethyl gallate remained unchanged during storage of the powder, but the concentration of ascorbic acid decreased, rapidly at first and then more slowly.
Microfiltration of cheese brine
Authors: Merin Uzi , Gordin Salli , Tanny Gerald B.
Published: June 2009

A new technique is described for the microfiltration of cheese brine. Soft cheese brine with viable counts/ml of up to 1·2 × 106bacteria and 2·2 × 104yeasts and moulds was filtered using a pleated tangential flow filtration cartridge of 0·2 εm pore size membrane. This filtration resulted in a 3–4 orders of magnitude reduction of bacteria and the complete rejection of yeast and mould from the permeate. Hard cheese brine with similar bacterial loads was treated with a 1·2 εm pore size membrane cartridge and the resulting permeate contained 2–3 orders of magnitude fewer bacteria and no yeasts or moulds. Flux decline during the filtration was a function of the number of microorganisms and the amount of N in the brine. A cleaning procedure using enzyme and acid washes was established in order to prolong membrane performance.
A fluorimetric method for determination ofPseudomonas fluorescensAR11 lipase in skim milk powder, whey powder and whey protein concentrate
Authors: Stead Donald
Published: June 2009

A method which was developed for assaying the extracellular lipases of psychrotrophic bacteria in milk (Stead, 1983, 1984) and which uses the fluorogenic substrate 4-methylumbelliferyl oleate has been adapted for use with skim milk powder (SMP), whey powder (WP) and whey protein concentrate (WPC). A five-fold increase in the concentration of sodium taurocholate (NaTC), in the mixture of NaTC and cetyltrimethylammonium bromide needed to dissociate lipase from milk proteins, removed the excessive sensitivity of the assay to variations in the concentrations of SMP, WP or WPC incorporated. Commercially available pancreatic lipase provided a suitable standard of lipolytic activity and as little as 1–2 μ could be detected in each assay system.
Milk production in concurrently pregnant and lactating goats mated out of season
Authors: Knight Christopher H. , Wilde Colin J.
Published: June 2009

Five lactating goats which had kidded normally in March were mated during seasonal anoestrus in May, at the time of peak milk production, after ovulation had been induced using gonadotrophin-releasing hormone (Knight et al. 1988). Milk yield was unaffected by the hormone treatment, and decreased at the same rate as that of control (non-pregnant) goats for the first 8 weeks of the pregnancy. Thereafter yield declined more quickly in the test goats and just before parturition (in October) was 57% of the control value. Following parturition in the test animals, yield rose rapidly as the second lactation was established. None became ‘dry’ at any stage. Yield continued to decline with advancing lactation in the controls, which were mated normally in October or November and dried-off in December. During their second (‘extra’) lactation in the winter the test animals produced 12% less than in a normal second lactation in summertime; during the year the extra lactation meant that the test animals produced 73% more milk than the controls. In some, a second concurrent pregnancy was established during the extra lactation, with the resuit that three lactations were obtained in the time normally taken for two. Mammary cell number and proliferation rate were both higher in the pregnant animals than in the controls in week 23 of the first lactation.
Optimization of the forewarming process with respect to deposit formation in indirect ultra high temperature plants and the quality of milk
Authors: Mottar Joseph , Moermans Renaat
Published: June 2009

The influence of preheating intensity was examined on deposit formation in an indirect ultra high temperature (UHT) plate heat exchanger and on some quality parameters of the UHT treated milk, such as taste, proteinase inactivation and protein destabilization during storage. Response surface methods were used to define the relationship between the forewarming conditions and the responses. More intense forewarming reduced the fouling rate in the UHT plate section, resulting in longer operation times. While a greater inactivation of the proteinase(s) in the milk was obtained, the taste of the UHT milk was adversely affected, as well as the physical stability during storage owing to higher sedimentation. An optimum temperature/time range for the preheating process could be defined within the temperature/time range of 76–80 °C/40–70 s at which adverse effects were minimal, and positive effects were maximized.
Study of acid milk coagulation by an optical method using light reflection
Authors: Banon Sylvie , Hardy Joël
Published: June 2009

A turbidimetric method, based on light reflection, was used to study acid coagulation of reconstituted skim milk at low temperature. Capillary viscosimetry, gelograph and laser granulometer techniques were also employed. Acidification of milk was produced by hydrolysis of glucono-δ-lactone. The general shape of the turbidimetric signal as a function of pH or time can be divided into three stages: a lag phase followed by a significant decrease and then a final rise. Two factors have a great influence on the development of milk turbidity, pH and temperature. Dynamic viscosity measurements can be related to the turbidimetric signal while laser granulometrie measurements cannot be correlated with changes in turbidity: the micelle size distribution remains constant until the first signs of gelation. As previous work showed, dynamic viscosity diminishes with acidification until a particular pH is reached (pH 5·9 at 15°C and pH 5·75 at 20°C). We have related this latter period to the turbidimetric lag phase. As milk turbidity became lower than its initial value (pH 5·75 at 15°C and pH 5·55 at 20°C), dynamic viscosity increased significantly. The release of material from micelles (β-casein and Ca) could explain this phenomenon. In the same way, further increase of turbidity at a particular pH value (pH 5·3 at both 15 and 20°C) coulcl be partly due to the reincorporation of soluble casein monomers in the micelle framework. As the onset of gelation was approached, turbidity still increased as a result of gel network formation.
Influence of liposome-encapsulated Neutrase and heat-treated lactobacilli on the quality of low-fat Gouda-type cheese
Authors: Skeie Siv , Narvhus Judith , Ardö Ylva , Abrahamsen Roger K.
Published: June 2009

Low-fat Gouda-type cheese (200 g fat/kg dry matter) was made on a pilot plant scale from cheesemilk to which heat-treated lactobacilli and/or Neutrase encapsulated in dehydrated rehydrated vesicles had been added. In cheese containing added Neutrase, there was increased proteolysis after the first day following cheesemaking. The cheese with added heat-treated lactobacilli developed increased amounts of amino N as well as increased amounts of acetaldehyde and other, unidentified, volatile compounds. The addition of heat-treated lactobacilli also influenced the texture of the cheese which was firmer but less cohesive.