Presence Of Milk Research Articles

Bioavailability of carotenoids and α-tocopherol from fruit juices in the presence of absorption modifiers:in vitroandin vivoassessment

The food industry is playing an increasing role in the development and marketing of new products although little is known regarding the bioavailability of the phytochemicals they contain. Our aim was to assess the effect of the presence of absorption modifiers (milk and iron) on the in vitro bioaccessibility and the serum response in vivo of carotenoids and alpha-tocopherol from fruit juices. Thirty-two young women participated in a three-period (21 d each) supplementation study with a 2-week wash-out in between. Subjects consumed consecutively 2 x 250 ml/d vitamin C-fortified juices supplied as fruit juice, fruit juice containing milk and fruit juice containing milk and iron. Fasting blood samples were collected before and after each supplementation period. In vitro bioaccessibility of carotenoids and alpha-tocopherol was assessed by a static digestion model. Vitamin E and carotenoids from both studies were determined by HPLC. In vitro, xanthophyll ester hydrolysis and transference of free xanthophylls and alpha-tocopherol into the micellar phase were higher in the presence of absorption modifiers. In vivo, consumption of the fruit juices provoked significant increments (within-subject) of alpha-tocopherol and some carotenoids in serum. Dose-adjusted increments in serum of some carotenoids were higher when subjects consumed juices with milk and milk plus iron, although differences did not reach statistical significance. In conclusion, the presence of milk and milk plus iron do not influence the bioavailability of carotenoids and alpha-tocopherol from fruit juices in vivo. Our results support the use of in vitro models to assess food-related factors affecting bioavailability of carotenoids and tocopherols from foods.

Stability of antioxidants in an apple polyphenol–milk model system

The stability of antioxidants in an apple polyphenol–milk model system was examined. The model system consisted of skim milk fortified with pH-neutralised apple polyphenols (AP, 0–200mg per 100ml milk), with or without ascorbic acid (100mg per 100ml milk). Physical and chemical changes were evaluated after thermal treatment (120°C, 5min) and oxidative storage (20°C and 38°C, up to 12 weeks). Antioxidant capacity was determined using both oxygen radical absorbance capacity (ORAC) assay and ferric reducing antioxidant power (FRAP) assay. Significant antioxidant capacity was detected in the presence of milk. Antioxidant capacity was retained during thermal treatment but decreased slowly during storage.The concentration of ascorbic acid decreased rapidly, and was close to zero after 2-week storage at 38°C or 10-week storage at 20°C. The brownness of the polyphenol–milk system increased over storage duration of 0–12 weeks; this effect was retarded by the addition of ascorbic acid. This high polyphenol–milk has demonstrated good physical stability.

Relationship between haptoglobin and serum amyloid A in milk and milk quality

The objective of this study was to evaluate relationships between the presence in milk of the major bovine acute phase proteins, haptoglobin (Hp) and serum amyloid A (SAA), and milk quality parameters. Composite milk samples were collected from 89 clinically healthy dairy cows and analysed for Hp and SAA, total protein, casein, and whey protein levels, casein number, proteolysis, total fat and lactose levels, and somatic cell count (SCC). Milk samples with detectable levels of Hp showed lower total protein and casein levels than those samples without Hp, whereas milk samples with detectable levels of SAA had lower casein number and lactose level than samples without detectable SAA. Samples with detectable levels of acute phase proteins also showed an elevated SCC. The results suggest that the presence of Hp and SAA in milk might indicate unfavourable changes in milk composition, especially in relation to protein quality.

Effects of Corn Silage Derived from a Genetically Modified Variety Containing Two Transgenes on Feed Intake, Milk Production, and Composition, and the Absence of Detectable Transgenic Deoxyribonucleic Acid in Milk in Holstein Dairy Cows

The objectives were to compare the chemical composition, nutritive value, feed intake, milk production and composition, and presence in milk of transgenic DNA and the encoded protein Cry1Ab when corn silages containing 2 transgenes (2GM: herbicide tolerance: mepsps and insect resistance: cry1Ab) were fed as part of a standard total mixed ration (TMR) compared with a near isogenic corn silage (C) to 8 multiparous lactating Holstein dairy cows in a single reversal design study. Cows were fed a TMR ration ad libitum and milked twice daily. Diets contained [dry matter (DM) basis] 45% corn silage, 10% alfalfa hay, and 45% concentrate (1.66 Mcal of net energy for lactation/kg of DM, 15.8% crude protein, 35% neutral detergent fiber, and 4.1% fat). Each period was 28-d long. During the last 4 d of each period, feed intake and milk production data were recorded and milk samples taken for compositional analysis, including the presence of transgenic DNA and Cry1Ab protein. There was no significant difference in the chemical composition between C and 2GM silages, and both were within the expected range (37.6% DM, 1.51 Mcal of net energy for lactation/kg, 8.6% crude protein, 40% neutral detergent fiber, 19.6% acid detergent fiber, pH 3.76, and 62% in vitro DM digestibility). Cows fed the 2GM silage produced milk with slightly higher protein (3.09 vs. 3.00%), lactose (4.83 vs. 4.72%) and solids-not-fat (8.60 vs. 8.40%) compared with C. However, the yield (kg/d) of milk (36.5), 3.5% fat-corrected milk (34.4), fat (1.151), protein (1.106), lactose (1.738), and solids-not-fat (3.094), somatic cell count (log10: 2.11), change in body weight (+7.8kg), and condition score (+0.09) were not affected by type of silage, indicating no overall production difference. All milk samples were negative for the presence of transgenic DNA from either trait or the Cry1Ab protein. Results indicate that the 2GM silage modified with 2 transgenes did not affect nutrient composition of the silages and had no effect on animal performance and milk composition. No transgenic DNA and Cry1Ab protein were detected in milk.

Role of milk constituents on critical conditions and deposit structure in skimmilk microfiltration (0.1 μm)

Crossflow microfiltration (0.1 μm) of skimmed milk is widely used in the dairy industry to separate casein micelles from soluble proteins. The accumulated matter at the membrane surface turns into an irreversible deposit in critical hydrodynamic conditions (CHC) ( J/ τ w) crit that irreversibly alters filtration performance. The aim of this work was to identify the milk constituents responsible for CHC and to evaluate the role of constituents (casein micelles, soluble proteins, minerals) on the microfiltration performance and deposit structure. An original methodology of filtration based on step-by-step τ w variation at constant flux was used with dairy fluids of variable and controlled composition. Casein micelles were shown to be the milk constituents responsible for the apparition of the CHC, creating an irreversible deposit at the membrane surface. Soluble proteins had no effect on the set-up of the CHC, but their presence in milk increased by 20% the irreversible fouling. The presence of the mineral aqueous phase of milk played a role in CHC set-up and irreversible fouling. Calcium ions are supposed to create bonds in the deposit between the membrane and the micelles and between micelles themselves.

Nutritional quality of human milk from Mediterranean lactating women: a preliminary approach towards personalised nutrition

Early life nutrition plays a key role in the future adult health. Human milk, the only natural source of food for the newborn, is in this way a food of predilection and should ensure an adequate metabolic programming. Indeed, breastfeeding has been shown to be beneficial for growth, development of neurological and cognitive functions, and prevention of some diseases in adulthood. These beneficial effects might be due to the presence in milk of polyunsaturated fatty acids, especially arachidonic and docosahexaenoic acids, that are essential for good development of the newborn [1] and have a biological imprinting on the expression of various enzymes involved in lipid metabolism [2]. These effects should also be linked to the presence of various proteins (insulin, leptin, bile salt-stimulated lipase, apolipoproteins, etc.).

Maternal Milk Contains Antimicrobial Factors That Protect Young Rabbits from Enteropathogenic Escherichia coli Infection

Enteropathogenic Escherichia coli (EPEC) colibacillosis represents a major cause of lethal diarrhea in young children in developing countries. EPEC strains also infect numerous mammal species and represent a major economical problem in rabbit industry. Protection against this pathogen is a challenging goal both in humans and in other mammal species. Despite a good knowledge of the pathogenicity mechanisms of EPEC, the intrinsic and environmental factors that control the expression of EPEC virulence in mammals remain unknown. For instance, the exacerbated sensitivity of young mammals to EPEC infection is still unexplained. Our goal was to investigate if age or other factors, like milk consumption, could be determinants that trigger the disease. We used rabbits as an animal model to study the role of milk in the sensitivity to an EPEC infection. Weaned and suckling rabbits were orally inoculated with EPEC strain E22 (O103:H2:K-) at 28 days of age, and the evolution of the disease was investigated in the two groups. In addition, in order to better characterize the interactions between milk and EPEC, we determined in vitro bacterial growth and the abilities of EPEC cells to adhere to epithelial cells in the presence of milk. Our results demonstrate a protective role of milk in vivo in association with in vitro antibacterial activity. These effects are independent of the presence of specific anti-EPEC antibodies.

Assessment of a reproduction rhythm based on the body condition of rabbit doe: preliminary results

The efficiency of rabbit farm mainly depends on the fertility and prolificacy of does, which in turn are modulated by genetic, feeding and management factors. The most important management factor for rabbit does is the reproductive rhythm.The aim of this work was to assess a reproductive rhythm in which the artificial insemination (AI) is done according to the body condition of doe. The study, involved 100 New Zealand White multiparous does submitted to AI for 5 consecutive cycles. Does were divided into 2 groups: CONTROL AI at 11d post partum and CONDITIONED AI when they reach a certain perirenal fat depot (between 15 and 30 g) estimated by ultrasound scanning. If does were too fat or lean, after an appropriate dietary protocol, they were weighed and submitted to ultrasound scanning again, and if they have a suitable body fat, artificially inseminated.At AI the does were weighed and submitted to ultrasound scanning of the perirenal region. Body Condition Score (loin, rump and hind leg), weight at kindling and at the weaning were also evaluated. On the day of insemination, does of both groups showed similar live weight and perirenal fat thickness (3862 vs 3813g and 0.64 vs 0.61 cm) respectively for CONDITIONED and CONTROL). These results were due to the fact that does are AI in different physiological stage; mainly lactating for the control group and dry for conditioned.Thus, during lactation does have a higher live weight for the presence of milk and for the higher incidence of the digestive tract, further the fat depot start to increase only after several days after weaning. Conditioned group showed higher fertility rate (83% vs 62%), number of live born pups (9.2 vs 7.4, P<0.05) and live weight of pups (512.8 vs 481.8 g, P<0.05), BCS of loin (1.1 vs 0.8, P<0.001), rump (1.0 vs 0.8, P<0.001) and hind leg (1.7 vs 1.4, P<0.001), perirenal fat weight (14.0 vs 10.9 , P<0.001), live weight at kindling (3865 vs 3553g, P<0.01), and doe at the weaning (3767 vs 3190g, P<0.01).In conclusion, conditioned rhythm, permitted to exhibit greater reproductive performance thanks to better energy balance. The higher cost of working hands would be counterbalanced by the higher fertility rate and prolificacy. Further investigation are needed to simplified and adapt conditioned rhythm to cycled production.

The influence of major components on the direct chromatographic recovery of a protein from transgenic milk

This work presents a systematic evaluation of the influence of lipids and casein on the performance of a chromatographic capture step for the recovery of a target protein from transgenic milk. Lactoperoxidase (LPO) was spiked at concentrations typical of those to be expected for transgenic proteins in commercial bovine milk and the dynamic adsorption of LPO to fixed beds of SP Sepharose FF studied in frontal analysis experiments. By removing successively selected components from whole milk, their individual influence on the dynamic adsorption behaviour of LPO could be studied. A mathematical model, fitted to the breakthrough curves of LPO, provided a quantitative measure of parameters describing mass transfer and adsorption in the column. A significant reduction in column capacity for LPO in the presence of milk or whey was recorded, which could be attributed to competing adsorption of alkaline earth metal ions to the cation exchange resin. While the high concentrations of lipids present in whole milk did strongly reduce the column permeability, no significant influence of either casein or low concentrations of lipids on the hydraulic properties of columns or on the adsorption of LPO could be detected. The results indicate that chromatography, which forms an essential part of all current large-scale processes for the recovery of proteins from transgenic milk, could potentially be moved further upstream. Alternatively, existing operations for the removal of lipid and casein could be re-designed so as to maximise product yields. This suggests that significant product losses during current pre-chromatography milk purification could be reduced or potentially even avoided.

How do the nature of forages and pasture diversity influence the sensory quality of dairy livestock products?

AbstractAbstract This review summarizes the recent developments in understanding of the relationships between the diet of animals and the sensory quality of dairy products. Feeding dairy cattle with maize silage by comparison with hay or grass silage leads to whiter and firmer cheeses and butter and sometimes to differences in flavour. Major differences in sensory characteristics were observed between cheeses made with milk produced by cows on winter diets (based on hay and grass silage) or turned out to pasture in the spring. Conversely, preserving grass as silage, by comparison with hay, has no major effect on cheese sensory characteristics, except on colour, the cheese being yellower with grass silage. Several recent experiments have shown a significant effect of grass botanical composition on cheese texture and flavour. These effects are due to the presence in milk of specific molecules directly introduced by feeding (carotenes, terpenes) or produced by the animals (plasmin, fatty acids) under the effect of specific diets.

The influence of the enzymatic composition of lamb rennet paste on some properties of experimentally produced PDO Fiore Sardo cheese

An experiment on PDO (Protected Designation of Origin) Fiore Sardo cheese making was carried out to assess the influence of rennet paste on cheese quality. Four different preparations of lamb rennet paste (A, B, C and D) were used. Rennet A came exclusively from suckling lambs slaughtered immediately after suckling, rennet B from suckling lambs not fed for 12 h, and rennets C and D from suckling lambs allowed to graze and slaughtered in the same way as A and B, respectively. In vitro lipolysis and multiple cheese-making trials were carried out for each rennet. The enzymatic composition of the prepared rennets was different. Lipolytic activity was assessed in vitro by measuring the quantity of free fatty acids released by hydrolysis of a sheep milk cream substrate. Rennet A had the greatest lipolytic activity, which had a strong preference for esters of short-chain fatty acids. The cheeses made using the different rennets did not differ significantly in their moisture, protein and fat content or in the nitrogen fractions which resulted from proteolysis. The cheese produced with rennet A had the highest lipolysis. Short-chain fatty acids, in particular butyric acid, were prevalent, as they were in the in vitro trials. The diet and the presence of milk in the abomasa was responsible for the enzymatic peculiarities of rennet A. Suckling stimulated the secretion of pre-gastric lipase from the pharingeal tissue. Thus, if one wishes to produce a rennet with the particular enzymatic composition necessary for a particular cheese, the diet and the slaughtering conditions of the lambs should be controlled.

The effect of varying the mixing formula on the quality of a yeast sweet bread and also on the process conditions, as studied by surface response methodology

SummaryThe objective of this work was to evaluate the effect of different ingredients on the mixing and fermentation times required to attain good bread quality. Results showed that variation in almost all ingredients affected mixing time; shortening being the exception. Longer mixing times were required as the concentration of ingredients was increased. Water‐soluble ingredients had a synergistic effect. The same behaviour was observed with total fermentation time, sugar, salt and milk powder having major effects. The only change in crumb colour was caused by egg. Crust colour was only affected by the presence of milk and sugar. It was concluded that it was possible to get good quality bread by varying the process conditions according to the formulation used. Non‐hygroscopic ingredients had a lesser effect on mixing and fermentation times. Predictive equations were obtained.

La collation matinale : fréquence, composition alimentaire et impact sur la nutrition des enfants

Morning snacks, initiated in the 1950's, tend to become a common practice among children, especially in nursery schools. To characterise this morning snack, food intake data from 624 children aged 3 to 10 years included in the INCA 1 survey and collected using a 7-day food record were analysed. Less than one child out of two had at least one morning snack during the week, generally between 10 and 10.30 am. Mainly composed of biscuits, pastries, or sweet beverages, this collation leads to an increased intake of carbohydrates, especially simple sugars. Moreover, this snack contributes to significant fat intake. Milk, the initial component of the collations, has become rare, and when it is present, it is always served with another food, principally biscuits. This supplementary intake during the morning was not associated with a low calorie breakfast and did not change energy intake at lunch. The repetition of this collation during the week leads to a higher average daily caloric intake. The presence of milk actually increases calcium intake, but few young French children are at risk of inadequacy for this nutrient. As a conclusion, a morning snack may contribute to unbalance children's diets and must be avoided, especially at school.

Determination of IgG levels in bovine bulk milk samples from different regions of Spain

Colostrum addition to milk for consumption is an unlawful practice. Furthermore, the higher whey protein/casein ratio of colostrum compared with milk causes severe technological problems. A high concentration of immunoglobulins has been generally accepted as an index of colostrum presence in milk. In this work, the levels of IgG have been determined by a non-competitive ELISA in 3,248 bulk bovine milk samples from different regions of Spain throughout one year. The mean value for IgG concentration obtained from all the samples was 0.257±0.122 mg/ml, within the range generally considered as acceptable for mature milk. The mean concentration obtained for all the samples collected in the spring was 0.288±0.125 mg/ml, significantly higher than the values found at the other seasons. The finding of some samples with very high values of IgG would suggest that the determination of immunoglobulin levels periodically would be a good parameter to control milk quality.

Invited review: beta-lactoglobulin: binding properties, structure, and function.

beta-Lactoglobulin (beta-LG) is the major whey protein of ruminant species and is also present in the milks of many, but not all, other species. Its amino-acid sequence and 3-dimensional structure show that it is a lipocalin, a widely diverse family, most of which bind small hydrophobic ligands and thus may act as specific transporters, as does serum retinol binding protein. Bovine beta-LG binds a wide range of ligands, but this may not be the reason for its presence in milk. In reviewing the structure and physicochemical properties of the protein, we present the structures of the ligands cholesterol (at a resolution of 2.0A, R = 0.221; Rfree = 0.295) and vitamin D2 (at a resolution of 2.4A, R = 0.212; Rfree = 0.297) each bound to the central binding cavity of bovine beta-LG at pH 7.3. Neither ligand is fully visible in the electron density maps, and the less well-ordered regions are the polar end groups at the mouth of the binding site. In a separate experiment, a mercury ion was bound to the free Cys121 (at a resolution of 2.2A, R = 0.218; Rfree = 0.288) in a way that transmitted a small structural change through Asp137 via Arg148 to the dimer interface. It is not clear if the known dissociation that arises from the reaction of beta-LG with HgCl2 results from this perturbation. In reviewing the structural studies that reveal the ligand binding sites for long-chain fatty acids, retinoids, and steroids, only the central location, common to all lipocalins so far examined, is occupied under the conditions used. We find that there is no crystallographic evidence of another ligand binding site in our crystals grown in approximately 1.3 M citrate, although low ionic strength studies in solution indicate the possible presence of at least one other low affinity site. The apparent ability of the binding site to accommodate a wide range of ligands may point to a possible physiological function. However, by considering the lipocalin family in general, and the species distribution of beta-LG in particular, some speculation as to the physiological function can be made. beta-Lactoglobulin has been reported as being implicated, inter alia, in hydrophobic ligand transport and uptake, enzyme regulation, and the neonatal acquisition of passive immunity. However, these functions do not appear to be consistent between species. Sequence comparisons among members of the lipocalin family reveal that glycodelin, found in the human endometrium during early pregnancy, is the most closely related to beta-LG. Although the function of glycodelin is also unknown, it appears to have effects on the immune system and/or to be involved in differentiation. It is proposed that beta-LG, over-expressed in the lactating mammary gland of many, but not all, species, is primarily an important source of amino acids for the offspring of those animals that produce it, but that this function arose by gene duplication from the physiologically essential glycodelin. The other functions that have been associated with beta-LG in the neonate are, therefore, fortuitous.

Relationships between ruminant management and sensory characteristics of cheeses: a review

This review summarises the last 10 years' knowledge established on the relationships between the management of animals (genetics, physiology and feeding) and the sensory quality of cheese. In the production of full-fat raw milk cheese, the cow's breed can modify the texture of cheeses because of differences in fat in dry matter content due to variations in the fat/protein ratio in milk. Within the same breed, large differences in texture and taste were observed between cheeses issued from milk differing by the genetic variant of β-casein (in dairy cows) or αs1- casein (in goats). Except in very early or late lactation, the physiological stage had no significant effect on cheese sen- sory characteristics. In contrast, mastitis has a well-known negative impact on cheese sensory pro- perties. Feeding dairy cows or goats with corn silage by comparison with hay or grass silage leads to whiter cheeses and sometimes to differences in flavour. Conserving grass as silage, by compari- son with hay, has no important effect on cheese sensory characteristics, except on colour, which is yellower with grass silage. Conversely, major differences in sensory characteristics were observed between cheeses made with milk produced by cows fed winter diets (based on hay and grass silage) or turned to pasture in the spring. Several recent experiments showed a significant effect of grass' botanical composition on cheese texture and flavour. Those effects are due to the presence in milk of specific molecules or structures directly induced by feeding (carotenes and terpenes) or produced by the animals (plasmin, fatty acids and casein micellar structures) according to their genetic or phy- siological characteristics or under the effect of specific diets. Milk / cheese / sensory characteristic / feeding / genetic characteristic

Screening processed milk for volatile organic compounds using vacuum distillation/gas chromatography/mass spectrometry.

An adaptation is presented of method 8261--from the Office of Solid Waste and Emergency Response Test Methods for Evaluating Solid Waste Physical/Chemical Methods (SW-846)-to analyze milk for an expanded list of volatile organic compounds is presented. The milk matrix exhibits a strong affinity for organic compounds and the surrogate based matrix normalization described in method 8261 provided accurate results. This method had the sensitivity necessary to detect volatile organic analytes at or below maximum contaminant levels (MCLs) set by EPA for drinking water. In a survey of milk samples available in Las Vegas, Nevada, 32 of 88 targeted volatile organic compounds (VOCs) were detected. Many of the detected VOCs have not previously been reported and a rationale for their presence in milk is presented.

263BINDING OF STALLION SPERM TO EQUINE AND BOVINE ZONAE PELLUCIDAE: EFFECT OF MILK, MILK PROTEINS AND GLUCOSE

The ability of sperm to bind to zonae pellucidae (ZP) has been correlated with fertilizing capacity of sperm in several species. Limited numbers of equine oocytes are available to perform such assays. Therefore, use of heterologous ZP to perform gamete binding tests with stallion sperm would be useful. We have found that addition of 10% of skim milk-based extender with glucose [EZ-Mixin®, Animal Reproduction Systems, Chino, USA;; (EZ)] to TALP significantly increased the number of stallion sperm bound to bovine ZP. Objectives of the present experiments were to determine: (1) if stallion sperm bind in similar numbers to equine and bovine ZP, and (2) the effects of skim milk, milk proteins and glucose on sperm binding to ZP. Denuded bovine (immature) and equine (mature) oocytes were stored at 5°C in salt solution (1.5M MgCl2, 40mM HEPES, 0.1% PVP). In Experiment I, 4 ejaculates from 2 stallions were centrifuged at 300g for 6min, and sperm pellets were resuspended in 1mL of TALP or EZ. Sperm were stained with Hoechst 33342, centrifuged, and resuspended to 2×106 sperm mL−1. Oocytes were placed into droplets of 45μL of TALP (7 to 10 oocytes/trt/ejac). Extended sperm (5μL) were added to oocytes, resulting in 2times105 sperm mL−1, and the mixutre was incubated for 2h at 38.5°C. Oocytes then were pipetted in TALP to remove loosely attached sperm and observed with fluorescence microscopy;; mean numbers of sperm bound to bovine and equine ZP for TALP were 29±1.9 and 36±2.6 (P&amp;gt;0.1) and for EZ, 149±5 and 152±6.3 (P&amp;gt;0.1), respectively. More sperm bound to ZP with EZ than to ZP with TALP (P&amp;lt;0.001). Experiment II used 4 ejaculates from 4 stallions. After initial centrifugation, sperm were resuspended in 1mL of each of six extenders: TALP, EZ, TALP containing 89.5mM glucose (TG), TALP containing 163.5mM glucose (THG), TALP containing 2.4mgmL−1 of skim-milk powder (TSM), and INRA 96® (IMV Technologies, L’Aigle, France) that contains 27mgmL−1 of native phosphocaseinate. Hoechst 33342-stained sperm and bovine oocytes were processed as described for Experiment I. Treatments containing milk proteins resulted in more sperm binding (P&amp;lt;0.01) than those without milk proteins (Table 1). In conclusion, use of bovine oocytes led to similar results for equine and bovine oocytes;; therefore, bovine oocytes can be used for binding assays with stallion sperm. High concentrations of glucose increased numbers of sperm bound to ZP;; however, presence of milk or milk proteins was more effective in enhancing binding of sperm to ZP. INRA96 contains relatively low glucose (67mM) and one milk protein. Therefore, we hypothesize that native phosphocaseinate may cause increased sperm binding to ZP. Table 1 Mean sperm bound per ZP±SEM (n=38–40/group)

The resistance to heat of thermo-resistant streptococci attached to stainless steel in the presence of milk.

Skim milk residues had a significant impact on the sensitivity to heat of a dairy isolate of the thermo-resistant, Streptococcus thermophilus. Cells of S. thermophilus (H) suspended in water or in milk had D values at 60 degrees C of 2.0 and 14 min, respectively. Cells of S. thermophilus (H) attached to stainless steel in the presence of water or milk had D values at 60 degrees C of 2.2 and 8.1 min, respectively. The attached cells in both experiments were heat-treated in the presence of water. The increase in heat resistance could not be fully attributed to individual components (caseinate or whey) in the milk. The potential for thermo-resistant streptococci to survive heat treatment in a dairy manufacturing plant is therefore greater than may be expected for the organism in less complex environments.

The resistance to heat of thermo-resistant streptococci attached to stainless steel in the presence of milk

Skim milk residues had a significant impact on the sensitivity to heat of a dairy isolate of the thermo-resistant, Streptococcus thermophilus. Cells of S. thermophilus (H) suspended in water or in milk had D values at 60 degrees C of 2.0 and 14 min, respectively. Cells of S. thermophilus (H) attached to stainless steel in the presence of water or milk had D values at 60 degrees C of 2.2 and 8.1 min, respectively. The attached cells in both experiments were heat-treated in the presence of water. The increase in heat resistance could not be fully attributed to individual components (caseinate or whey) in the milk. The potential for thermo-resistant streptococci to survive heat treatment in a dairy manufacturing plant is therefore greater than may be expected for the organism in less complex environments.