bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of seasonal variation, urea addition and ultrafiltration on the heat stability of skim-milk powder
Authors: Kelly Philip M. 
Published: June 2009

SUMMARYThe 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

SUMMARYCephalotyre (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

SUMMARYThe 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

SUMMARYInterrelationships 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

SUMMARYAnalysis 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

SummaryHeat 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

SummaryKareish 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

SummaryThe 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

SummaryManipulations 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

SummaryTeat 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

SummaryMilk 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

SummaryThe 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

SummaryA 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

SummarySkim 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

SummaryTransfatty 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

SummaryThe 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

SummaryCasein 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

SummaryCasein 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

SummaryAn 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

SummaryThe 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.