bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ion exchange processing of skim-milk for food use
Authors: Burgess K. J. 
Published: June 2009

SUMMARYIon exchange is a unit operation which has several applications in the processing of skim-milk and whey. For example, in the field of whey processing, ion exchange is used in demineralization, lactose hydrolysis and in the pre-treatment of whey prior to protein recovery. In the case of skim-milk, applications include the manufacture of low Na milk and pre-acidification of skim-milk in casein manufacture. However, the ion exchange treatment of skim-milk to replace Ca ions with Na ions leads to far more fundamental changes with regard to the native protein conformation.The effect of Ca removal from skim-milk is essentially to disrupt the native casein micelle structure into unassociated molecules of Na caseinate. Skim-milk modified in this way shows increased stability to alcohol and heat and increased functionality of the skim-milk protein in terms of water binding, emulsification and foaming capacity. The viscosity of Ca-reduced skim-milk is also substantially increased.The improved functionality of Ca-reduced skim-milk makes the latter a potentially useful food ingredient in products where the above mentioned properties are important.
Fermentation of goat's milk by two DL-type mixed strain starters
Authors: Rysstad Gunnar , Abrahamsen Roger K. 
Published: June 2009

SummaryVariations in the biochemical performance of 2 DL-type mixed strain starters CH 01 and FDn grown in a sample of skimmed goat's milk I (obtained 2–3 weeks after parturition) and of goat's milk II (8 months after parturition) were studied, and results compared with those of the cultures grown in skimmed cow's milk. The initial levels of citrate differed in the 3 milks, with goat's milk II containing 0·7 mg/ml, goat's milk I 1·4 mg/ml and cow's milk 1·8 mg/ml. The production of diacetyl, α-acetolactic acid and acetoin was very low in goat's milk II. In goat's milk I the production of these compounds was higher, but still considerably lower than in cow's milk. Production of ethanol (EtOH) was similar in the 3 milks incubated with starter CH 01, but with FDn the production of EtOH was distinctly higher in goat's milk II. The total amount of CO2produced corresponded with the initial level of citrate; consequently the highest production was found in cow's milk and the lowest in goat's milk II. The use of different starters for fermented products made from goat's milk in early and late lactation is suggested.
Threonine aldolase and alcohol dehydrogenase activities inLactobacillus bulgaricusandLactobacillus acidophilusand their contribution to flavour production in fermented milks
Authors: Marshall Valerie M. , Cole Wendy M. 
Published: June 2009

SummaryCell-free extracts of bothLactobacillus bulgaricusandL. acidophilusdemonstrated threonine aldolase activity, the end product of which was acetaldehyde, the major flavour compound of yoghurt.L. acidophilusalso possessed an alcohol dehydrogenase activity capable of reducing acetaldehyde so that little yoghurt flavour was present in milks fermentation with this organism. Addition of threonine to fortified milk before fermentation withL. acidophilusincreased acetaldehyde production and resulted in a well flavoured product similar to that of yoghurt made withL. bulgaricus. The contribution of these 2 enzymes to flavour production is discussed.
Isolation andin vitrotranslation of mRNA from the calf abomasal mucosa and identification of an mRNA coding for a precursor of prochymosin
Authors: Nicholson Bruce H. , Jones Peter 
Published: June 2009

SummaryThe mRNA coding for prochymosin (prorennin) has been partly purified from calf abomasum. Thein vitrotranslation products of the total polyadenylated RNA show a major band on gel electrophoresis which reacts with antibody raised against purified chymosin. The mol. wt of 43000 is higher than expected from the reported amino acid sequence and would correspond to prochymosin with an unprocessed signal sequence of ∼ 17 amino acids. The synthesis of chymosin mRNA is age-related, and ceases by 3 months even in milk-fed calves.
Distribution, location, and ultrastructure of plasma cells in the uninfected, lactating bovine mammary gland
Authors: Nickerson Stephen C. , Pankey J. Woodrow , Boddie Nancy T. 
Published: June 2009

SummaryQuantitative cytological analysis demonstrated a marked and progressive increase in concentration of subepithelial plasma cells from milk-secreting parenchyma to the distal teat end mucosa in the normal, lactating bovine mammary gland. Parenchymal plasma cells exhibited typical ultrastructure with abundant, flattened stacks of rough endoplasmic reticulum, and hypertrophied Golgi components, while many cells in the teat end mucosa displayed an ergastoplasm distended with fine, flocculent material. Intraepithelial plasma cells were also observed in teat end mucosa. Results suggest that teat end tissues function by recruiting plasma cells to serve as protection against invading mastitis-causing organisms.
Chemical characterization of milk concentrated by ultrafiltration
Authors: Green Margaret L. , Scott K. John , Anderson Malcolm , Griffin Mary C. A. , Griffin Frank A. 
Published: June 2009

SummaryWhole milks concentrated 1·5–4-fold and acidified and citrated milks concentrated 2·8-fold by ultrafiltration at 50 °C were analysed for chemical changes relevant to further processing, storage or nutrition. Fat and protein were entirely retained in the concentrate. The retention of water-soluble vitamins, Ca, Mg, phosphate and trace minerals depended on the proportion bound to the protein. Ascorbic acid was rapidly destroyed during concentration. Because of the differential retention of nitrogenous components, protein comprised a progressively higher proportion of the total N as the milk became more concentrated. No denaturation of whey protein or disruption of casein micelles was detected during concentration of whole milk, but some solubilization of the casein occurred after citration. Reduction of fat globule size occurred early in the concentration process, damage to the fat globule membrane was indicated and the milk became more susceptible to lipolysis. Apart from a tendency for preacidified or precitrated concentrates to gel, no change in the susceptibility of the milks to heat damage was detected.
Physical and chemical properties of zabadi manufactured from skim milk powder reconstituted with sweet whey
Authors: El-Safty Mohamed S. , El-Zayat Ali I. 
Published: June 2009

SummaryZabadi was manufactured using reconstituted skim milk powder prepared with different ratios of water and sweet whey and the organoleptic properties and chemical composition of the milks were measured. Sweet whey could be used successfully to replace up to 50% of the water added for reconstitution, whilst with 75 or 100% whey a sweet off flavour appeared. However, these higher levels could be used for fruit flavoured zabadi, and about 40–60% less sucrose could be used because of the additional glucose + galactose contributed by the whey.
The 31P nuclear magnetic resonance spectrum of cows' milk
Authors: Belton Peter S. , Lyster Richard L. J. , Richards Colin P. 
Published: June 2009

SUMMARYThe 31P nuclear magnetic resonance spectrum of liquid milk was examined. Of the three peaks observed, the two larger were assigned to inorganic phosphate (Pi) and the seryl phosphate (SerP) residues of casein; the third peak was assigned to a phosphodiester, which is probably glycerophosphoryl choline. The pH-dependences of the chemical shifts of the Pi and SerP were measured with and without added EDTA, and the results confirm the assignments. The width of the Pi peak in milk is significantly greater than in similar solutions lacking casein, probably because of binding to, or chemical exchange with, the casein micelle. Most of the SerP residues in milk are not sufficiently mobile to have been detected in these experiments but a significant fraction of SerP residues is able to move freely and can be titrated.
Use of liposomes for proteinase addition to Cheddar cheese
Authors: Law Barry A. , King Joseph S. 
Published: June 2009

SUMMARYA commercial neutral proteinase was encapsulated in liposomes (multilamellar) and incorporated into cheese curd via the cheese milk. The milk proteins were protected from proteinase attack during curd manufacture. A significant proportion of the liposome-entrapped enzyme was retained in the curd and its subsequent release into the cheese matrix was inferred from an increased rate of β-casein breakdown.
Nutritional value of yogurt
Authors: Hewitt David , Bancroft Helen J. 
Published: June 2009

SUMMARYYogurt, made from fortified skim milk by conventional methods using Streptococcus thermophilus and Lactobacillus bulgaricus, was used in studies of the effect of fermentation on nutritional value of milk. In all experiments, the product was compared with the uninoculated base milk. The concentration of most vitamins was less in yogurt than in milk and was most noticeably so for biotin which was 60% less. The effect on folic acid content was inconsistent. In nutritional experiments with rats, high values for true digestibility, biological value and net protein utilization were obtained for both yogurt and its base milk, only minor differences being apparent between the two materials. In growth tests with rats, yogurt was not found to be consistently superior to the base milk when the milk was subjected to a double heat treatment to reduce bacterial contamination. Yogurt did not confer a nutritional advantage on fresh milk in this respect.
Quantification of β-casein in human milk
Authors: Chtourou Abdessatar , Brignon Ghislaine , Ribadeau-Dumas Bruno 
Published: June 2009

SUMMARYA method is described for preparing immunologically homogeneous human milk β-casein, against which monospecific rabbit antiserum was prepared. The antiserum was used to quantify β-casein, the major human casein, by rocket Immunoelectrophoresis in individual milk samples. However, it was found that in most samples β-casein occurred together with degradation products originating from its proteolysis by plasmin. Immunological quantification of human β-casein, treated with plasmin for various time periods, showed that rocket height was not affected by proteolysis up to degradation states clearly more advanced than those observed in all samples of fresh human milk tested. Assays of 150 individual milk samples from 80 women, covering a lactation period of up to 730 d, gave an average concentration of β-casein (native+degraded) of 4·67±0·89 standard deviation (g/1); extremes at 2·1 and 7·3 g/1 did not vary significantly during the period under study. Comparison of this average value with an accepted casein content of 4·4 g/1 (Macy & Kelly, 1961) showed that the casein content of human milk is underestimated when obtained by N determinations on milk and on its supernatants at pH 4·6 (whey). Caseins other than β-casein occurred only in minute amounts, if at all.
Does β-lactoglobulin occur in human milk?
Authors: Brignon Ghislaine , Chtourou Abdessatar , Ribadeau-Dumas Bruno 
Published: June 2009

SUMMARYAlthough β-lactoglobulin (β-lg) has been considered to be absent from human milk, recent results of other workers, based on immunological reactions between human milk and rabbit antiserum to bovine β-lg, suggest that this protein may be present. Although our results show similar immunological reactions, we consider that lactoferrin is responsible for these, as it was the only reactive protein species which could be prepared to homogeneity. Indeed two types of antibodies were found by ELISA test in the antisera to bovine β-lg. One of them would be able to bind loosely to human lactoferrin, but its binding sites would not be antigenic in the rabbit.
Effect of serotonin on the motility of smooth muscles in teats of lactating cows
Authors: Messom Georgette Vandeputte-Van , Burvenich Christian , Peeters Georges 
Published: June 2009

SUMMARYThe effects of serotonin, injected into one udder artery, on teat smooth muscle function were investigated in four lactating cows. Motility of longitudinal smooth muscles was recorded by a plethysmographic technique, and sphincter function by measuring milk leakage from the full udder. Serotonin (40, 120 and 360 μg) activated teat muscle tonicity and reduced the volume of milk leakage. The effects on longitudinal smooth muscles were reduced by mianserin and ketanserin (0·375, 1·5 and 6 mg) and by methysergide (1·5 mg). These blocking substances were also effective (0·2, 0·6 and 1·8 mg respectively) in antagonizing the inhibiting action of serotonin on milk leakage. It is suggested that serotonin effects are mediated by receptors of the S2-type.
Increasing cheese yields by high heat treatment of milk
Authors: Marshall Richard J. 
Published: June 2009

SUMMARYMilk was heated at 97 °C/15 s to denature ∼ 30% of the whey protein and then used to make Cheshire cheese. Measurements of para-κ-casein production indicated that heating milk did not inhibit the enzymic action of rennet, but additional Ca and an initial pH of 6·4 were required for normal coagulation and curd-firming. In the experimental cheeses, about 4·5% more dry matter was recovered compared with controls made with pasteurized milk owing to a 6·7 and 0·7% increase in protein and fat recovery respectively. Experimental cheeses tended to be too moist and the curds did not fuse as well but these problems could be overcome by raising the scald temperature and cheddaring the curds. When the moisture in non-fat solids of control and experimental cheeses was similar (61%), the flavours and textures were not significantly different. The procedure requires little modification to existing commercial plant and should be suitable for varieties of cheese with higher moisture content and more crumbly texture than Cheddar.
Use of Platelet Aggregometer to monitor the chymosin-initiated coagulation of casein micelles
Authors: Bringe Neal A. , Kinsella John E. 
Published: June 2009

SUMMARYThe chymosin-initiated coagulation of casein micelles was followed by monitoring light transmission using a Platelet Aggregometer. The release of macropeptide by chymosin was monitored using fluorescamine. The lag period in the clotting reaction was proportional to clotting time and the reciprocal of enzyme concentration. The average rate of coagulation, which was approximately equal to the reciprocal of clotting time (Tc), increased in proportion to enzyme concentration at low enzyme concentrations and reached a limiting value at high enzyme concentrations. The percentage hydrolysis at the Tc was 47 ± 5% in the presence of 20 mM-CaCl2 and it was calculated that a 5-fold decrease in the speed of the enzyme-catalysed reaction would decrease this value at the Tc to 43 ± 5%. The possible uses and limitations of the Platelet Aggregometer for determining the influence of the chemical environment on the velocity of the chymosin-catalysed reaction and para-casein micelle aggregatability are discussed.
Purification and characterization of the extracellular proteinase ofPseudomonas fluorescensNCDO 2085
Authors: Fairbairn David J. , Law Barry A. 
Published: June 2009

SUMMAEYPseudomonas fluorescensNCDO 2085 produced a single heat-stable extracellular proteinase in Na caseinate medium at 20 °C and pH 7·0. The proteinase was purified to electrophoretic homogeneity using chromatofocusing, gel filtration and ion-exchange chromatography. The purification procedure resulted in a 158-fold increase in the specific activity and a yield of 3·5% of the original activity. The enzyme is a metalloproteinase containing Zn and Ca, with an isoelectric point at 5·40±0·05 and a mol. wt of 40200±2100. It is heat-stable having D-values at 74 and 140 °C of 1·6 and 1·0 min respectively; 40 and 70% of the original activity remained after HTST (74 °C/17 s) and ultra high temperature (140°C/4 s) treatments respectively. The amino acid composition of the proteinase was determined and compared with those from otherPseudomonasspp.
Pre partum milk fat secretion and concentrations of progestins, prostaglandin and oestrone sulphate in mammary fluid of the goat
Authors: Thompson Gordon E. , Goode Jane A. 
Published: June 2009

SummaryAs much secretion as possible was removed manually twice daily, from both mammary glands of 6 late-pregnant goats beginning on d 137 of gestation. Removing mammary fluid before parturition stimulated fluid secretion by different amounts in individual goats. The mean volume of fluid secreted pre partum by the goats correlated directly with their secretion of triglyceride and the percentage composition of C18 fatty acids in the triglyceride fatty acids; the volume also correlated with the concentration of progestins, but not prostaglandin F2α or oestrone sulphate, in the fluid.
Use of monoclonal antibodies for radioimmunoassay of water buffalo milk progesterone
Authors: Capparelli Rosanna , Iannelli Domenico , Bordi Aldo 
Published: June 2009

SummaryIn order to standardize a radioimmunoassay of milk progesterone as a routine method for confirmation of oestrus and diagnosis of pregnancy in water buffalo, monoclonal antibodies against progesterone were produced. Hybridomas were prepared by fusing spleen cells from a Balb/c mouse immunized with progesterone 11α-hemisuccinate–bovine serum albumin conjugate with the mouse myeloma cell line NS-1. Thirty wells out of 94 secreted anti-progesterone antibodies. Of the ten independent hybridomas derived, one (AF65) was suitable for the quantification of milk progesterone by radioimmunoassay. The tracer used in the assay was progesterone-11α-hemisuccinate ([2-125I]iodohistamine). The sensitivity of the assay was 50 pg/tube. The mean progesterone concentration at oestrus was 0·8±0·2 ng/ml increasing to 8·5±0·8 ng/ml 24 d later in pregnant animals.
An automated enzymic micromethod for the measurement of fat in human milk
Authors: Lucas Alan , Hudson Geoffrey J. , Simpson Peter , Cole Timothy J. , Baker Brian A. 
Published: June 2009

SummaryMost (98%) of the fat in human milk is present as triglycerides. This paper describes the use of a clarification procedure that enables the level of human milk fat to be determined by measurement of glycerol released by enzymic hydrolysis of triglycerides. The method requires only 10–50 μl milk, thus presenting a possible technique for work with small mammals, and is suitable for use with autoanalysers, permitting rapid sample throughput.
Effects of parity and stage of lactation on adenosine triphosphate, somatic cell count and antitrypsin content in cows' milk
Authors: Emanuelson Ulf , Olsson Thomas , Mattila Tiina , Åström Göran , Holmberg Olof 
Published: June 2009

SummarySignificant effects of parity and stage of lactation were found on ATP content, somatic cell count and antitrypsin content when using morning milk samples from 39 cows over a period of 18 months. A close similarity was evident between variation in ATP and somatic cell count, except during the first 10 d after parturition when the variation in ATP was more pronounced. The same result was obtained in the whole material as well as in a healthy subset. This study shows clearly that parity and stage of lactation must be taken into account when establishing normal values for ATP as an indicator of mastitis.
Proteolysis of Cabrales cheese and other European blue vein cheese varieties
Authors: Fernandez-Salguero Jose , Marcos Andres , Alcala Manuel , Esteban Maria Asuncion 
Published: June 2009

SummaryThe extent and level of proteolysis were evaluated in Cabrales and five other European blue vein cheese varieties, Bleu de Bresse, Danablu, Edelpilzkäse, Gorgonzola and Roquefort, by analysing their different N-containing constituents and determining the degree of casein hydrolysis. The electrophoretic patterns of the caseins in the cheeses confirmed their strong proteolysis, components featuring the lowest electrophoretic mobility offering the greatest resistance to subsequent hydrolysis. Component αs1 — I was detected in all varieties studied with the exception of Roquefort cheese.
Binding of zinc to bovine and human milk proteins
Authors: Singh Harjinder , Flynn Albert , Fox Patrick F. 
Published: June 2009

SummaryZn binding by whole bovine and human casein and by purified bovine caseins and whey proteins was investigated by equilibrium dialysis. Bovine αs1casein had the greatest Zn-binding capacity (˜ 11 atoms Zn/mol). Protein aggregation was observed as Zn concentration was increased and- the protein precipitated at a free Zn concentration of 1·7 mM. Zn binding increased with increasing pH in the range 5·4–7·0 and decreased with increasing ionic strength. Competition between Zn and Ca was observed for binding to αs1-casein indicating common binding sites for these two metals. Bovine β-casein bound up to 8 atoms Zn/ mol and precipitated at a free Zn concentration of ˜ 2·5 mM, while K-casein bound 1–2 atoms Zn/mol. Whole bovine and human casein bound 5–8 atoms Zn/mol and precipitated at a free Zn concentration of ˜ 2·0 mM. Scatchard plots for Zn binding to caseins showed upward convexity, possibly due to Zn-induced association of caseins. Apparent average association constants (K¯app) for all caseins were similar (log K¯app3·0–3·2). Enzymic dephosphorylation of αs1- or whole bovine casein markedly reduced, but did not eliminate, Zn binding. Thus, phosphoserine residues appeared to be the primary Zn-binding sites in caseins. With the exception of bovine serum albumin. which bound over 8 atoms Zn/mol, the bovine whey proteins, β-lactoglobulin, α-lactalbumin and lactotransferrin, had little capacity for Zn binding.
Zinc binding in bovine milk
Authors: Singh Harjinder , Flynn Albert , Fox Patrick F. 
Published: June 2009

SummaryAbout 90% of the Zn in bovine skim milk was sedimented by ultracentrifugation at 100000 g for 1 h. About half of the non-sedimentable Zn was non-dialysable, indicating that it was associated with protein, probably non-sedimented casein micelles. Casein micelles incorporated considerable amounts of Zn added to skim milk as ZnCl2, and at Zn concentrations ≥ 16 mM coagulation of casein micelles occurred. Ca was displaced from casein micelles by increasing ZnCl2concentration and ˜ 40% of micellar Ca was displaced by 16 mM-ZnCl2. Micellar Zn, Ca and P1 were gradually rendered soluble as the pH of milk was lowered and at pH 4·6 > 95% of the Zn, Ca and P1were non-sedimentable. These changes were largely reversible by readjustment of the pH to 6·7. About 40% of the total Zn in skim milk was non-sedimentable at 0·2 mM-EDTA and most of the remainder was gradually rendered soluble by EDTA over the concentration range 1–50 mM. This indicates that there are two distinct micellar Zn fractions. No micellar Ca or P1was solubilized at EDTA concentrations up to 1·0 mM, indicating that both colloidal calcium phosphate (CCP) and casein micelles remained intact under conditions where the more loosely bound micellar Zn fraction dissolved. Depletion of casein micelles of colloidal Ca and P1by acidification and equilibrium dialysis resulted in removal of Zn, and in colloidal Pi-free milk non-dialysable Zn was reduced to ·-2 mg/1 (˜ 32% of the original Zn). Thus, ˜ 32% of the Zn in skim milk is directly bound to caseins, while ˜ 63% is associated with CCP. Over 80% of the Zn in colloidal Pi-free milk was rendered soluble by 0·2 mM-EDTA, indicating that the casein-bound Zn is the loosely bound Zn fraction in casein micelles. A considerable fraction of the Zn in acid whey (pH 4·6) co-precipitated with Ca and Pion raising the pH to 6·7 and heating for 2 h at 40 °C, indicating that insoluble Zn phosphate complexes form readily under these conditions. Studies on dialysis of milk against water, or dilution of milk or casein micelles with water, showed that CCP and its associated Zn is very stable and dissolves only very slowly at pH 6·6. The nature of Zn binding in casein micelles may help to explain the lower nutritional bioavailability of Zn in bovine milk and infant formulae compared with human milk.