bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accelerated ripening of Cheddar cheese with the aminopeptidase of Brevibacterium linens and a commercial neutral proteinase
Authors: Hayashi Kiyoshi , Revell Dean F. , Law Barry A. 
Published: June 2009

SummaryPartly purified extracellular aminopeptidase from Brevibacterium linens was used to accelerate Cheddar cheese ripening. It was found that although the aminopeptidase was unstable in acidic buffer, it was highly stable in Cheddar cheese; negligible amounts of the enzyme activity were lost during 3 months' maturation. A better score for flavour in sensory analysis of enzyme-treated cheese was obtained by the combination of the aminopeptidase and a commercially available metalloproteinase (Neutrase) than by the metalloproteinase alone.
Interactive effect of H2S production from cysteine and methanethiol production from methionine in milk-fat-coated microcapsules containing Brevibacterium linens
Authors: Kim Sun C. , Kim Misun , Olson Norman F. 
Published: June 2009

SummaryThe interactive effect of two of the major Cheddar cheese flavour compounds, H2S and methanethiol, was studied in milk-fat-coated microcapsules containing Brevibacterium linens, cysteine and methionine. Two substrates, cysteine and methionine, were either co-encapsulated with B. linens or encapsulated separately with B. linens and mixed together. The production of H2S from cysteine in microcapsules was slightly reduced by the methanethiol produced from methionine. However, the presence of H2S stabilized methanethiol produced from methionine in milk-fat-coated microcapsules and subsequently increased the level of methanethiol. Without H2S, the methanethiol in milk-fat-coated microcapsules disappeared rapidly after 48 h. By making separate microcapsules at each optimum environment and mixing together, the cells could operate in the protected and ideal environment of the microcapsules to form products that diffused out and acted as reactants with products from other microcapsules.
Calcium ion activities of cooled and aged reconstituted and recombined milks
Authors: Augustin Mary-Ann , Clarke Phillip T. 
Published: June 2009

SummaryMilk powders were subjected during manufacture to the following treatments: low-, medium- or high-heat, indirect or direct UHT preheat, or no preheat. The Ca2+ activity–pH profiles of reconstituted milks (9% total solids, TS) in the pH range 6·06–6·98 and reconstituted concentrated milks (19·6% TS) and recombined concentrated milks (26% TS, 18% SNF, 8% fat) in the pH range 6·27–6·69 were determined. Statistical analysis of the results using a (– In Ca2+ activity) transformation was used to quantify the effects of pH, preheat treatment and fat incorporation on Ca2+ activity. pH had a dominant effect on Ca2+ activity and the effects of preheat treatment and fat incorporation were small in comparison. Depending on the batch of milk used for preparation of powders, pH accounted for 98·8–98·9%, 96·4–96·7% and 93·7–97·3% of the total variation in Ca2+ activity in reconstituted milks, reconstituted concentrated milks and recombined concentrated milks. The corresponding contributions of preheat treatment to variation in Ca2+ activity were 0·26–0·47%, 0·34–1·67% and 0·24–0·40%. The addition of fat to reconstituted concentrated milk to yield recombined concentrated milk with the same SNF: water ratio resulted in 0·03–3·71 % variation in Ca2+ activity. The results suggested that differences in heat stability among powders subject to different preheat treatments are not likely to be linked to Ca2+ activity.
Elevation of bovine serum C-reactive protein and serum amyloid P component levels by lactation
Authors: Morimatsu Masami , Watanabe Atsushi , Yoshimatsu Kumiko , Fujinaga Toru , Okubo Masahiko , Naiki Masaharu 
Published: June 2009

SummaryC-reactive protein (CRP) and serum amyloid P component (SAP), which are known to increase in sera from humans and many other animals with acute inflammation caused by infection, toxic drug administration or injury, were previously purified from bovine serum. These serum levels were determined by enzyme-linked immunosorbent assay (ELISA) using specific antiserum to bovine CRP or SAP which was prepared by immunizing rabbits and goats with each purified protein. Among 68 healthy Holstein cows, 45 non-lactating cows had levels of CRP and SAP of 20·6±1·4 and 27·6 ± 1·3 μg/ml respectively; 23 lactating cows had higher levels of CRP and SAP (76·0±13·6 and 38·3±5·5 μg/ml respectively). In the latter group, there was a high correlation between milk yield and serum CRP levels (P <0·001). From these observations, it was assumed that lactation might stimulate CRP synthesis rather than SAP synthesis in bovine liver as an acute phase reaction, and that CRP might be called a lactation-associated protein.
Xanthine oxidase/dehydrogenase in mammary gland of mouse: relationship to mammogenesis and lactogenesisin vivoandin vitro
Authors: Hayden Thomas J. , Brennan Denise , Quirke Katherine , Murphy Paddie 
Published: June 2009

SummaryXanthine oxidase/dehydrogenase (XO/XDH) increases at mid gestation in mammary gland but not in liver of the mouse and remains elevated until the pups are weaned at 20 d post partum. The increase in enzyme activity is due neither to alteration in activators or inhibitors nor to a production of a variant enzyme with altered catalytic properties. The increase is precededin vivoby a surge of prolactin-like activity (placental lactogen) in plasma, and prolactin is required for induction of XO/XDH in explant culturein vitro. Induction of XO/XDHin vivoandin vitroprecedes the full histological differentiation of the gland. In addition, induction of XO/XDHin vitrooccurs more rapidly and at lower concentrations of prolactin than does histological differentiation. Thus although XO/XDH is present in milk, increased XO/XDH activity is an early event in mammogenesisin vivoandin vitrorather than a terminal component of differentiation.
Evidence and characterization of temperate bacteriophage inStreptococcus salivariussubsp.thermophilusSt18
Authors: Carminati Domenico , Giraffa Giorgio 
Published: June 2009

SummaryLysogenic strains ofStreptococcus salivariussubsp.thermophiluswere studied using induction with mitomycin C (MC). The induction and presence of temperate phage were investigated carrying out tests on sensitive strains, electron microscopy and phage DNA analysis. Forty-fiveStr. salivariussubsp.thermophilusstrains were subjected to induction with MC and growth of the various cultures was evaluated. Only one strain of those tested showed lysis after adding MC, thus indicating a possible lysogenic state, 0·5μg MC/ml being the optimal dose. Two Φ18 phage-sensitive strains out of 45 were isolated in which this phage behaved as virulent, causing lysis of the culture in broth, but no lysis plaques on agar medium were detected. The St18 strain was cured by u.v. irradiation but no mutants sensitive to the Φ18 phage were found among the clones non-inducible by MC. The presence of phages having a hexagonal isometric head and a long non-contractile tail in the lysate obtained after inducing the St18 strain was confirmed by examination under the electron microscope. Study of the phage DNA showed a genome size of 40·9 ± 0·5 kb without cohesive end fragments. In addition, the restriction map of the phage genome was constructed. This study has demonstrated lysogeny inStr. salivariussubsp.thermophilusand also that several phage infections ofStr. salivariussubsp.thermophilusstarters may have an ‘endogenous’ origin.
Heat stability of recombined milk: influence of lecithins on the heat coagulation time-pH profile
Authors: McCrae Catharina H. , Muir D. Donald 
Published: June 2009

SummaryTwo types of lecithin, namely egg and soya lecithin, were investigated as potential stabilizers of recombined milk. They were incorporated into recombined milk both before and after homogenization (20·7 MPa; 60 °C). Their presence at homogenization changed neither mineral equilibria nor homogenization efficiency. However, heat stability varied significantly irrespective of batch of low-heat skim milk powder used in recombined milk. The variation in heat stability depended on type of lecithin. Soya lecithin proved to be a very effective stabilizer. It improved heat stability over a wide pH range (6·3–7·1) and the effect occurred even when the lecithin was added after homogenization. In contrast, egg lecithin destabilized the system to heat at pH < 6·7 by converting a Type A into a Type B heat coagulation time-pH profile if it was incorporated before homogenization; after homogenization it had no effect. The effects of both egg and soya lecithin on the heat stability of recombined milk strongly suggest that interactions occur between phospholipids and milk protein.
Computer simulation of the hydraulic milking method
Authors: Butler M. Clare , Grindal Robert J. 
Published: June 2009

SummaryA mathematical model of the interactions within a milking machine teatcup has been developed, which describes the relationship between liner wall movement, pressures and flow rate when milking without an air inlet. It is based on equations of motion for a column of incompressible fluid and requires a second-order, non-linear differential equation to be solved. Incorporating a non-return valve allows hydraulic milking to be modelled, and the comparison between predicted and measured pressures, flow rates and liner wall movement when milking hydraulically is shown. The model can be used to optimize milking conditions to reduce vacuum peaks, improve liner opening and thus maximize flow rate.
K+ and Cl− transport by mammary secretory cell apical membrane vesicles isolated from milk
Authors: Shennan David B. 
Published: June 2009

SummaryThe transport of K+ (Rb+) and Cl− by membrane vesicles isolated from bovine milk has been studied using ion-exchange column chromatography. K+ (Rb+) and Cl− accumulation by the vesicles was time-dependent and was almost abolished by 0·1% Triton X-100, suggesting that uptake represents ‘real’ transport rather than binding. K+ (Rb+) uptake was influenced by the anion in solution in a manner suggesting that influx is sensitive to changes in vesicle membrane potential. Similarly, Cl− uptake was found to be sensitive to vesicle electrical potential: Cl− influx was enhanced by inside positive potentials. Cl− uptake was not saturable with respect to external Cl−. The results suggest that K+ (Rb+) and Cl− cross the apical membrane by way of conductance pathways. The similarity between ion transport by skim milk membrane vesicles and that of the apical aspect of the intact mammary epithelium suggests that the former may be a good model to study solute transport by the apical membrane of mammary secretory cells.
Different bacteriophage resistance mechanisms inStreptococcus salivariussubsp.thermophilus
Authors: Larbi Dejla , Decaris Bernard , Simonet Jean-Marc 
Published: June 2009

SummaryStreptococcus salivariussubsp.thermophilusstrain NST5 exhibited a temperature-dependent defence mechanism against the virulent bacteriophages φ.B1.2 and φA1.1. It was active at 42 °C but not at 30 °C as demonstrated by a significant increase of both plaque size and efficiency of plaquing. This defence mechanism did not affect host-dependent phage replication and did not interfere with phage adsorption to NST5. These results suggest that it interfered with phage development. The phages φT33, φT58, φD1, φT21 and φT9, belonging to the same phage type as φB1.2, were examined for their ability to infect NST3 and NST5. Restriction modification systems of different specificity were detected in NST3 and NST5; host-dependent phage replication was detected at 30 and 42 °C; an abortive defence mechanism was detected in NST5 which was active at 42 °C, but not 30 °C, and was independent of restriction modification action or interference with phage adsorption. Our investigations of phage-host interactions showed that the twoStr. salivariussubsp.thermophilusstrains studied avoided attack by related bacteriophages by evolving at least three different resistance systems.
Effects of prolonged treatment of lactating goats with bovine somatotropin on aspects of adipose tissue and liver metabolism
Authors: Vernon Richard G. , Faulkner Anne , Finley Eric , Watt Paul W. , Zammit Victor A. 
Published: June 2009

SUMMARYThe effects of prolonged (22 weeks) treatment of lactating goats with bovine somatotropin on the metabolism of adipose tissue and liver has been investigated. Somatotropin treatment resulted in smaller adipocytes, decreased rate of fatty acid synthesis and decreased total acetyl-CoA carboxylase activity of adipocytes, but with no change in the proportion of this enzyme in the active state. The rate of acylglycerol glycerol synthesis from glucose of adipocytes tended to decrease as did total glucose utilization by the tissue. Glucose conversion to lactate was unchanged by somatotropin treatment but glucose conversion to other products was decreased. Maximum response of adipose tissue to insulin was unchanged but the sensitivity to insulin decreased on somatotropin treatment. Treatment with somatotropin had no effect on basal lipolysis and decreased maximum response to the β-agonist isoproterenol, but this probably reflects the rate of isoproterenol-stimulated lipolysis varying with cell volume in adipocytes. No apparent change in response either to α2-adrenergic agonists or to adenosine was apparent. The number of β-adrenergic receptors was unchanged in adipocyte membranes but the number of α2-adrenergic receptors increased. The rate of hepatic gluconeogenesis in vitro, the activity of key gluconeogenic enzymes and the modulation of the rate of gluconeogenesis by butyrate were unchanged except for the effect of this latter agent on gluconeogenesis from propionate. Hepatic ketogenic activity, as indicated by the activity of carnitine palmitoyl-CoA-transferase-1 and the concentrations of carnitine and acyl carnitines, was unchanged by treatment. Thus at the end of a prolonged period of treatment with somatotropin in lactating goats, lipid synthesis in adipose tissue is still decreased but no effects on liver lipid and carbohydrate metabolism were apparent.
Microparticle-enhanced nephelometric immunoassay for caseinomacropeptide in milk
Authors: Prin Christine , Bari Nezha El , Montagne Paul , Cuilliere Marie-Louise , Bene Marie-Christine , Faure Gilbert , Humbert Gerard , Linden Guy 
Published: June 2009

SummaryA microparticle-enhanced nephelometric immunoassay has been developed for the determination of caseinomacropeptide (CMP) in bovine milk. It is based on the nephelometric quantification of the competitive immunoagglutination of a microparticle–CMP conjugate with an anti-κ-casein (κ-CN) antiserum. This one step immunoassay was sensitive (detection limit in reaction mixture, 16μg/l), accurate (linear recovery of CMP in dilution overloading) and reproducible (CV 7–14% for within and between run precision). Because of the specificity of the polyclonal antiserum used, it was necessary to separate CMP from κ-CN by ultrafiltration before the quantification of bovine milk CMP. Under the conditions of milk ultrafiltration used, κ-CN was entirely retained (> 99·5%) but the concentration of CMP measured in milk ultrafiltrates was underestimated (by ∼25%) compared with its concentration in whole milk. Microparticle-enhanced nephelometric immunoassay of CMP, with a calibration range from 0·32 to 20 mg/1 for 20- fold diluted milk ultrafiltrate, allowed contamination of bovine milk by rennet whey as low as 5 ml/1 to be detected. Applied to ultrafiltrates from milk stored at 4 °C, this immunoassay also detected proteolysis of κ-CN not revealed by measurement of κ-CN concentration in milk. A statistical lower limit of 3·21 mg/1 was determined as the increase in CMP concentration in milk ultrafiltrates that indicated probable κ-CN proteolysis in the milk sample. Previously demonstrated to be an easy to perform method for assaying the main proteins of bovine milk, microparticle-enhanced nephelometric immunoassay thus also appeared to be appropriate to quantify CMP so as to detect slight contamination of milk by whey and to indicate the proteolysis of κ-CN during milk storage at low temperature.
Bovine milk procathepsin D and cathepsin D: coagulation and milk protein degradation
Authors: Larsen Lotte B. , Benfeldt Connie , Rasmussen Lone K. , Petersen Torben E. 
Published: June 2009

SummaryCathepsin D is an indigenous aspartic proteinase in bovine milk. By competitive enzyme-linked immunosorbent assay the amount of immunoreactive cathepsin D and procathepsin D in bovine skim milk was estimated to be 0·4 μg/ml. Immunoreactive cathepsin D purified from whey consisted of a small fraction of mature cathepsin D, but the major form was the proenzyme procathepsin D. A preparation of bovine milk procathepsin D was, like mature cathepsin D, able to degrade purified αs1-, αs2-, β- and κ-casein and α-lactalbumin, while β-lactoglobulin was resistant to cleavage. The cleavage sites in these proteins were determined and compared with those of chymosin. Cathepsin D was capable of generating the αs1-I, β-I, β-II and β-III fragments originally described from the action of chymosin on the respective caseins, and these fragments were subjected to further proteolysis. Cathepsin D was also able to liberate the caseinomacropeptide from purified κ-casein, and to coagulate bovine skim milk. This demonstrated that milk contains an indigenous coagulation enzyme present mainly in the whey fraction.
Cholesterol oxidation in butter and dairy spread during storage
Authors: Nielsen Jacob H. , Olsen Carl Erik , Jensen Claus , Skibsted Leif H. 
Published: June 2009

SummaryIn a dairy spread (800 g lipid/kg, 10 g salt/kg) based on 750 g milk fat/kg and 250 g rapeseed oil/kg fat in 15 g extruded catering packaging, there was a more significant accumulation of cholesterol oxidation products than in butter (minimum 800 g lipid/kg, 12 g salt/kg) in 10 g extruded catering packaging when stored at 4 or at 20 °C. There was a lag phase of 7 weeks in cholesterol oxidation in dairy spread stored at 4 °C, while no lag phase was observed for storage at 20 °C. Total concentrations of oxysterols were, however, very similar for dairy spread stored at 4 and 20 °C after 13 weeks storage (∼ 12 μg/g milk lipid); storage at – 18 °C almost prevented cholesterol oxidation (∼ 4 μg/g milk lipid). For butter, cholesterol oxidation was less pronounced at 4 °C (< 3 μg/g milk lipid) than at – 18 °C (∼ 4 μg/g milk lipid) and 20 °C (∼ 7 μg/g milk lipid). 7-Ketocholesterol was the dominant oxidation product, with 1·3 and 5·7 μg/g milk lipid in butter and dairy spread respectively after 13 weeks storage at 4 °C.
Effect of medium-chain fatty acids in mould ripened cheese on the growth ofListeria monocytogenes
Authors: Kinderlerer Judith L. , Matthias Helen E. , Finner Paul 
Published: June 2009

SummaryListeria monocytogenesandList. innocuawere isolated from commercial soft ripened and blue-veined cheeses manufactured in France, mainly from Brie cheese made from unpasteurized milk. Five isolates wereList. monocytogenesserotype 1/2 and two wereList. innocua. Examination of Bleu d'Auvergne cheese with the cryoscanning electron microscope showed that many conidia spores were present in the blue veins in close contact with the cheese surface. There were few conidia spores in the Brie, mostly on the outside of the cheese but not in contact with the surface. High concentrations of free dodecanoic (lauric) acid (1·77–2·50 g/kg cheese) and tetradecanoic (myristic) acid (2·54–6·38 g/kg cheese) were found in the veins of the blue cheese, but concentrations in the white regions were much lower. Free lauric and myristic acids were not detected in the Brie cheeses. There was no difference in the overall fatty acid composition of the fat in the surface ripened and blue-veined cheeses, although higher concentrations of free medium-chain fatty acids were found in a blue cheese compared with a surface ripened cheese. The pH and fat content were higher in regions with obvious fungal growth, the blue veins of Fourme d'Ambert and the rind of Brie. Free lauric acid dissolved in butteroil inhibited multiplication in broth at pH 7·0 of a test strain ofList. monocytogenesisolated from Bleu d'Auvergne. Some inhibition was seen with hexanoic, octanoic, decanoic and tetradecanoic acids. We suggest that the presence of localized concentrations of free medium-chain fatty acids (dissolved in the fat) in the blue veins of blue mould ripened cheese could act as natural preservatives and inhibit the growth of listerias in conditions where (if present), one would otherwise expect them to grow.
Purification and properties of an acid lipase from Penicillium roqueforti
Authors: Lamberet Gilles , Menassa Aimé 
Published: June 2009

REFERENCESThe extracellular acid lipase produced by Penicillium roqueforti strain 1173 was purified by precipitation with 50 % ethanol, DEAE Sephadex A 50 ion exchange chromatography and 2 successive treatments with SP Sephadex C 50. An ~ 400-fold purification with a 35 % yield was obtained. The enzyme was active from pH 1·7–10·5, with an optimum activity pH of 6·5 at 20 °C and 6·0 at 30 °C. A second minor optimum appeared close to pH 2·5 and there was a minimum activity at pH 3·6. In the presence of 0·1 M-CaCl2 at 30 °C, the optimum was at pH 5·5, also the pH value where inhibition by CaCl2 was least (9%). The pH stability curve at 30 °C showed no discontinuities and had a maximum between pH 3·7 and 6·0. At pH 6·5 activity at 5 °C represented 37 % of the maximum value, which was reached at 35–40 °C and the apparent activation energy was about 5·42 kcal mol-1. Between pH 4·0 and 7·0, the ratio of hydrolysis velocity at 30 °C compared to that at 20 °C ranged from 2·1 to 1·2. At pH 6·0, the enzyme began to be inactivated at temperatures above 35 °C with decimal destruction times (D values) of 150, 29 and 4 min for respective temperatures of 40, 45 and 50 °C. In terms of substrate specificity the maximum activity was obtained with tricaproin whilst with tributyrin, tricaprylin, butter oil and triolein relative velocities were 22, 6·7, 3·0 and 1·5% respectively of that for tricaproin whilst Tween 20 and triacetin were 2·5 and 2% respectively.
Sodium chloride and moisture changes in Romano-type cheese during salting
Authors: Guinee Timothy P. , Fox Patrick F. 
Published: June 2009

SUMMARYThe apparent diffusion coefficients for NaCl in Romano-type cheese salted by brining or dry salting were ∼0·23 cm2/d. A plot of the natural logarithm of % salt-in moisture against distance was almost linear, the slope of which is the distance over which the salt concentration decreases by a factor of 1/e (0·368). Such plots may be useful in predicting the concentration of NaCl at any point in the cheese after any period of brining. After 9 d brining, the water to salt flux (ratio of outflow of water to inflow of NaCl) decreased from 2·42 at the surface to ∼0·5 in the middle zone of the cheese and increased again to > 1 at greater distances from the cheese/brine interface.
Accelerated ripening of Cheddar cheese with a commercial proteinase and intracellular enzymes from starter streptococci
Authors: Law Barry A. , Wigmore Anne S. 
Published: June 2009

SUMMARYIntracellular cell-free enzyme extracts (CFE) of cheese starter bacteria significantly enhanced the flavour-accelerating effect of commercial neutral proteinase without increasing the gross proteolysis in Cheddar cheese. Peptide and amino acid N were released more rapidly in CFE-treated cheeses, compared with those treated with neutral proteinase or untreated controls.