Effect of heat on milk

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Article: Effect of heat stress on milk production and its composition of Holstein Friesian crossbred dairy cows

Article: Effect of heat stress on milk production and its composition of Holstein Friesian crossbred dairy cows

Abstract: The aim of this research was to observe the effect of heat stress on milk yield and milk compositions of Holstein Friesian crossbred (HF) dairy cows. To fulfill the objectives, a total of 9 Holstein Friesian crossbred cows were selected for this study. Green grasses (German, Para) were supplied adlibitum and concentrate feeds (mixture of wheat bran, rice polish, mustard oil cake, di-calcium phosphate and salt) were supplied at the rate of 2.0 kg/day/cow. Management practices for all the cows were similar following the BAU Dairy farm practices. Data were collected on milk yield (l/h/d), relative humidity (%) and barn temperature ( 0 C). The obtained temperature humidity index (THI) of July, August, September and October were 84.95, 81.99, 81.40 and 79.57, respectively. The highest THI was found in July which indicated higher heat stress during this month. A significant difference (p<0.05) in milk yield of cows was found among different months of July to October. The highest milk yield (6.10±0.50 l/h/d) was found in October among observed months. The compositions of milk such as total solids (TS), solids-not-fat (SNF), fat, protein, lactose, and ash also differed significantly (p<0.01). The highest values (%) of TS, SNF, fat, protein, lactose and ash content of milk were found in October as 12.63, 8.80, 3.83, 3.69, 4.39 and 0.72, respectively and lowest values (%) were in July as 12.20, 8.50, 3.71, 3.50, 4.30 and 0.69, respectively due to the high THI value. From these results, it is concluded that heat stress has strong effect on milk yield and milk composition of HF cows in Bangladesh. Management strategies are needed to minimize heat stress and attain optimal dairy animal performance.
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ALLERGENICITY OF COW'S MILK PROTEINS: I. Effect of Heat Treatment on the Allergenicity of Protein Fractions of Milk as Studied by the Dual-ingestion Passive Transfer Test

ALLERGENICITY OF COW'S MILK PROTEINS: I. Effect of Heat Treatment on the Allergenicity of Protein Fractions of Milk as Studied by the Dual-ingestion Passive Transfer Test

and alpha-lactalbumin. idem: Studies on the allergenicity of cow’s milk. The effect of heat treatment on the allergenicitv of milk and protein frac- tions from milk as tested in guinea p[r]

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Heat induced whey protein reactions in milk : kinetics of denaturation and aggregation as related to milk powder manufacture : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology

Heat induced whey protein reactions in milk : kinetics of denaturation and aggregation as related to milk powder manufacture : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology

which occurs in late season milk (Phelan et al. , 1982; Singh & Newstead, 1992). The binding of retinol to �-lg increases its denaturation temperature but decreases the denaturation enthalpy, as measured in a DSC study of �-lg saturated with retinol (Puyol et al. , 1994). The concentration of retinol in whole milk powder from New Zealand Friesian-cross herds is at a minimum during December but increases during the latter stages of the season. The effect of retinol may not be very significant as the naturally occurring concentrations are small, and saturation of �-lg with retinol may be required before there is any observable change. In addition, most of the retinol in milk is esterified with fatty acids (Perez & Calvo, 1995). The denaturation temperature and enthalpy of �-lg increase when it binds palmitic acid (Puyol et al. , 1994). In milk the amount of fatty acids bound is about 1 .0 mol per mol of �-lg dimer (Perez & Calvo, 1995). The binding of fatty acids, rather than retinol, to �-lg may be more important in determining its thermal stability. The concentration of fat increases during the latter part of the season in New Zealand milk (Holmes & Wilson, 1984), although it is not known how this affects the free fatty acid concentration and its binding to �-lg in skim milks. The increase in Na and total Ca content in late season milk may have caused the increase in denaturation, although the concentration of soluble Ca decreases (Pearce & Newstead, 1970; Keogh et al. , 1982). Varunsation et al. (1983) showed that the effect of Ca and Na were to promote denaturation and aggregation reactions in WPC solutions.
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High pressure induced starch gelatinisation and its application in a dairy system : a thesis presented in partial fulfilment of the requirements for the Doctor of Philosophy in Food Science at Massey University, Auckland, New Zealand

High pressure induced starch gelatinisation and its application in a dairy system : a thesis presented in partial fulfilment of the requirements for the Doctor of Philosophy in Food Science at Massey University, Auckland, New Zealand

The functionality of starch in a dairy application was tested using acid milk gels as a model system. Skim milk with added starch (waxy rice or potato starch) was either pressure treated (500 MPa, 20°C, 30 min) or heat treated (80°C, 30 min) and subsequently acidified to form acid milk gels. The addition of waxy rice starch resulted in firmer acid milk gels, and increasing the amount of starch caused an increase in the firmness of both pressure-treated and heat-treated samples. However, pressure-treated samples with added potato starch did not show significant changes in the firmness whereas the heat-treated counterparts showed a marked increase in the firmness as the level of potato starch increased. The difference between the effects of the two different starches can be explained by the extent of starch gelatinisation in skim milk. Starch granules absorb water during gelatinisation whether induced by pressure or heat which effectively increases milk protein concentration in the aqueous phase to form a denser protein gel network on acidification. The firmness of acid milk gels can be increased by adjusting the pH at pressure or heat treatment to higher than the natural pH of milk. The effect of pH at pressure or heat treatment and addition of starch on the acid milk gel firmness was additive and independent of each other up to a starch addition level of 1%.
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Freezing point of raw and heat treated goat milk

Freezing point of raw and heat treated goat milk

Freezing point belongs to the key properties of milk. Many factors affect it. From among the main milk constituents, lactose and chlorides mostly influence FP. If combined, they account for 75–80% of the final FP. The remaining 20–25% of the FP value is affected by other milk constituents – cal- cium, magnesium, lactates, phosphates, citrates, urea, etc. (Fox and McSweeney, 1998). Milk fat glo- bules, casein micelles and whey proteins play a neg- ligible role in the reduction of milk FP (Bhandari and Singh, 2003). Kessler (1984) also stated that milk fat exerted no effect on milk FP and milk pro- teins displayed a minimum action as far as the value of freezing point is concerned.
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Chemical characteristics of gel obtained from blend of colostrum and skim milk under different heat treatments conditions

Chemical characteristics of gel obtained from blend of colostrum and skim milk under different heat treatments conditions

Pimpale, 1988). This gel proper ty has been traditionally used to prepare sweet desserts. The gel obtained with first and second milking is very tough and therefore it is common practice to dilute the colosturm with milk or water to obtain gel of suitable textural attributes. The present study is a preliminary report on physico-chemical attributes of such gels formation of colostum harvested from second milking from gir cow, which were blended with skim milk. Bearing in mind the fact that colostrums and its components are very sensitive to heat and other conditions, its processing at low heat treatment can be preserve its bioactivity. Therefore present study was undertaken in order to make the standardize process parameters for preparation of colostrum based product blended with skim milk and analysed for effect of heat treatments on chemical characteristics of gel obtained from colostrum and skim milk blended (CSMB) product.
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Pool boiling of milk in a stainless steel pot under closed condition

Pool boiling of milk in a stainless steel pot under closed condition

The present experimental study is concerned with the heat transfer during nucleate pool boiling of milk in a stainless steel pot under closed conditions. Reported are the results of the effect of the different heat rate of inputs varying from 240 to 360 watts on the heat transfer coefficient under pool boiling. The evaporated water condensed at the inner surface of the condensing cover was collected as fresh water. To quantify the effect of rate of heat input on the convective heat transfer coefficient, the Rohsenow correlation was applied with the constants from the experiments. The convective heat transfer coefficients were estimated in the range of 160.51 to 374.52 W/m 2 o C for the given heat inputs. The nucleate boiling heat flux was predicted to vary exponentially with the excess temperature of the stainless steel pot surface above the saturation temperature of the milk. The experimental errors in terms of percent uncertainty were also evaluated.
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STUDIES ON THE ALLERGENICITY OF COW'S MILK

STUDIES ON THE ALLERGENICITY OF COW'S MILK

Effect of Heat Denaturation on the Aller- genicity of Milk as Tested by Challenge of Animals Sensitized to the Protein Fractions. Each of 10 animals received three injec-.[r]

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Behavioral Pattern of Native Food Isolates of Yersinia enterocolitica and Yersinia intermedia under Simulated Time Temperature Combinations of the Food Chain

Behavioral Pattern of Native Food Isolates of Yersinia enterocolitica and Yersinia intermedia under Simulated Time Temperature Combinations of the Food Chain

The public health significance of Yersinia spp. gives a new dimension to the prevailing food chain, wherein the foods do get exposed to heat and cold treatments. In this study, the effect of heat treatment on the native isolates of Yersinia enterocolitica CFR 2301 and Y. intermedia CFR 2303 revealed the D-values ranging from the lowest of 0.08 min at 65˚C in skim milk/beef gravy to the highest of 18.52 min at 50˚C in beef gravy. The heat sensitivity of both these cul- tures was in the order of Milli-Q water > 0.85% saline > skim milk > beef gravy. The z-values of the test cultures ranged from 7.55˚C for Y. intermedia to 12.08˚C for Y. enterocolitica. The heat sensitivity in Y. enterocolitica appeared to be related with growth incubation temperatures and also fatty acid profile of cell membrane. The effect of low tem- perature treatments (−20˚C, 0˚C and 4˚C for 20 d) in water, saline and skim milk revealed the ability of Y. enterocolitica to survive more efficiently at −20˚C, while Y. intermedia was more tolerant at 0˚C. In packaged drinking water, Y. en- terocolitica could survive and grow at 4˚C and 16˚C, while at 30˚C, inactivation was rapid. The findings did indicate that heat and cold treatments would not always ensure safety from Y. enterocolitica and Y. intermedia in the food chain.
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Probiotic fermented almond “milk” as an alternative to cow-milk yoghurt

Probiotic fermented almond “milk” as an alternative to cow-milk yoghurt

Probiotics in almond-based matrices were considered as a means of obtaining fermented products which would cover both the current demand for health-promoting foods and for alternatives to standard yoghurts. Firstly, the combined effect of high pressure homogenisation (HPH) and heat treatment on the physical stability of almond “milk” was studied. The beverage was homogenised by applying 62, 103 and 172 MPa (MF1, MF2 and MF3 respectively); MF3 was also combined with two different heat treatments (85 °C-30 min (LH) and 121 °C-15 min (HH)). Both microstructure and colloidal stability were analysed in all the processed samples to select the most suitable treatment with which to obtain a stable product. The selected almond milk was then fermented with probiotic Lactobacillus reuteri and Streptococcus thermophilus and the final product was characterised throughout cold storage time (28 days) as to pH, acidity, serum retention and starter viability. A sensory evaluation and probiotic survival to in vitro digestion was also conducted. The results showed that the physical and structural almond-milk properties were affected by both HPH and heat treatments, obtaining the greatest stability in MF3-LH samples. The fermented milk permitted probiotic survivals above the level suggested as minimum for ensuring health benefits during the entire controlled time and, hence, can be considered as a functional food. No differences in the sensory acceptability of the product were found between 1 and 28 storage days. Therefore, a new, functional, fermented product was developed, which was suitable for targeted groups, such as the lactose-intolerant and cow-milk-protein allergic populations.
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ALLERGENICITY OF COW'S MILK PROTEINS

ALLERGENICITY OF COW'S MILK PROTEINS

and alpha-lactalbumin. idem: Studies on the allergenicity of cow’s milk. The effect of heat treatment on the allergenicitv of milk and protein frac- tions from milk as tested in guinea p[r]

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Effect of Temperature on the Shelf life of Nono (Locally Fermented Milk) and Yoghurt

Effect of Temperature on the Shelf life of Nono (Locally Fermented Milk) and Yoghurt

The microbial load in yoghurt kept under refrigeration (4°C) maintained the same number of microbial count from week 1 to week 3 as 1.8 x 103CFU/ml but increased in the 4th week to 2.7 x 103. This might be due to the failure in power supply which leads to the rise in temperature giving room to microorganism to multiply. It is a well-known fact that microorganism multiply rapidly under normal temperature than at lower temperatures. There was a slight decrease to 2.3 x 103 on the 6th and 7th week this might possibly be as a result of the growth of psychotropic bacteria which grows in lower temperatures even below 5°C. Rodríguez-Alcaláet al., (2009) suggested that longer refrigeration time allows increased growth of psychotropic microorganisms and concomitant production of heat-stable enzymes, especially proteinases and lipases. The result of this present study contradicts the findings of Rodríguez- Alcaláet al., 2009 which states that Cooling to a temperature of 4ºC makes the bacteria inactive and prevents them to grow and produce the lactic acid. Li and Li (1998) suggested that the tolerable limit of microbial load of yoghurt should be equal or less than 1.0x10 5 cfu/ml comparing this to the present studies, it is
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Physical and rennet coagulation properties of recombined cheese milk made from milk protein concentrate (MPC 56) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology

Physical and rennet coagulation properties of recombined cheese milk made from milk protein concentrate (MPC 56) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology

Effect of pre heat treaunent during MPC powder manufacture on the physical and rennet coagulation properties of reconstituted skim milk 20% MPC powder without an additional milk fat and [r]

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Influence of changes in level of feeding on milk production

Influence of changes in level of feeding on milk production

Decrease per month in daily yield in lb. 724, the only one in which the yields month by month were reported. Grazing periods had to be included, but from examination of the data they do [r]

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Influence of plant cover on the share of the soil heat flux in the heat balance of the active surface

Influence of plant cover on the share of the soil heat flux in the heat balance of the active surface

On the other hand, when the equation of the heat balance refers to periods which are shorter (a month, a day, or an hour), the share of soil heat in the heat balance of the surface can be substantial. This applies mostly to active surfaces with very poor plant cover (eg waste land) or to surfaces with no plant cover at all (stubble or ploughed fields). On such surfaces, particularly after long periods without precipita- tion, when the soil is over dry, temporary values of the soil heat flux can reach even 50% of the value of the net radiation Rn, and, in particular cases, they may even exceed that value (Kêdziora, 1995). In some cases, the accuracy of estimation of the G flux can have a vital influence on the quality of esti- mation of other, turbulent components of the heat balance (S and LE) (Allen et al., 1998). It is particularly important when methods based on the principle of conservation law of energy (eg Bowen method) (Olejnik and Eulenstein, 1997) are used for the estimation of fluxes S and LE.
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Thermochemical Heat Recovery Based on External Heat Engine

Thermochemical Heat Recovery Based on External Heat Engine

2) to increase stability of catalytic burning in non- adiabatic operation mode of catalytic burner (due to heat withdrawal into engine or just heat losses into environment), that is, in decreasing temperature profile in the layer of deep oxidation catalyst. Indeed, for catalytic combustion of ÑÍ 4 even on the most active Pt and Pd catalysts the temperature of about 550–650°C is required. Herewith, catalytic burning of Í 2 and CO can run at sufficiently lower temperature of about 200– 300°Ñ. That is, upon catalytic combustion of hydrogen- containing gas the combined area of catalytic burning and heat withdrawal can be extended into the area of lower temperatures without danger of flame failure. This provides theoretical possibility to increase significantly the useful portion of heat withdrawn into the engine.
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The impact of seasonal variations of New Zealand raw milk on the heat stability of skim milk

The impact of seasonal variations of New Zealand raw milk on the heat stability of skim milk

to their loose structure. To some extent, both dephosphorylation and hydrolysis of the caseins has been found in heat-treated milk (Belitz, Grosch, & Schieberle, 2004; Farrell et al., 2004; Fox, 1981). Whey protein represents about 18-20% out of total of milk proteins and contains four major proteins: β-lactoglobulin (β-Lg) 50%, α-lactalbumin (α-La) 20%, blood serum protein (BSA) 10% and immunoglobulin (Ig) 10%. Whey proteins has a globular structure, which makes them heat unstable, as the result, whey proteins denaturation (unfolding) takes place at a temperature above 65℃, but it mostly happens at temperatures above 80°C. Whey protein denaturation is a two-step process, protein unfolding followed by aggregation (De Wit & Swinkels, 1980; Mulvihill & Donovan, 1987; Roefs & Kruif, 1994). At the temperature above 65℃, the interactions between the denatured whey proteins and the casein micelles, the conversion of soluble Ca, Mg and phosphate to the colloidal state takes place (Singh & Waungana., 2001) . The level of whey protein denaturation depends on the time, the temperature of treatment, pH of milk, ionic strength (McSwiney, Singh, & Campanella, 1994; Oldfield, Singh, Taylor, & Pearce, 2000; Qi, Brownlow, Holt, & Sellers, 1995) and the level of β- Lg denaturation, since it represents about 50% of all whey protein (Morr., 1985). Due to the
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Physical and rennet coagulation properties of recombined cheese milk made from milk protein concentrate (MPC 56) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology

Physical and rennet coagulation properties of recombined cheese milk made from milk protein concentrate (MPC 56) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology

The effects of heat treatment and homogenization on the physical and rennet coagulation properties of recombined cheese milk 40% total solids made from reconstituted milk protein concent[r]

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Effect of short-term heat acclimation on endurance time and skin blood flow in trained athletes

Effect of short-term heat acclimation on endurance time and skin blood flow in trained athletes

Fourteen male athletes were recruited from active members of the national all-star table tennis and the national all-star badminton teams from Taiwan. The athletes recruited for this study were six badminton and eight table tennis players. (See exclusion criteria below.) The athletes were full-time college students at the National Taiwan Sport University in Taoyuan, Taiwan, not heat acclimated, and had been residing at the same location (altitude of 250 meters above sea level) for 3–4 years. During the study period, the months of November through March, the average monthly ambient temperature and relative humidity were: 19.9°C and 68% (November); 16.5°C and 67% (December); 15.3°C and 79% (January); 14.4°C and 77% (February); and 17.5°C and 82% (March), respectively. Summer month ambient temperature and relative humidity averaged 28°C–30°C and 80%–88%, respectively. The age, height, body mass, body surface area, and maximum oxygen uptake (VO 2max ) of the subjects were (mean ± standard devia- tion [SD]): 19.6 ± 1.2 years; 171.6 ± 4.7 cm; 64.7 ± 5.0 kg; 1.78 ± 0.08 m 2 ; and 53.0 ± 5.3 mL/kg −1 per minute −1 (with
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Effect of drought and heat stresses on plant growth and yield: a review

Effect of drought and heat stresses on plant growth and yield: a review

The alterations in root growth and distribution reduces shoot growth and functions as an effect of root-to-shoot sig- nalling with contribution of plant hormones and other factors (eg nitrogen, calcium, pH) acting as signal mole- cules. The plant stress hormone, ABA, has long been re- cognized to act as a major chemical root-to-shoot stress signal under both stresses. Both stresses induce stomatal closure, decrease the transpiration rate and photosynthesis activity particularly through the effect on photosystem PS II, and lead to earlier crop maturity and poor productivity. Other responses include accumulation of compounds of low molecular mass (eg proline and gibberellins), anatomical deformations at the tissue, cellular, and sub-cellular levels. Expression of heat shock proteins and other proteins is an adaptation strategy to high temperatures. C3 (eg wheat) compared to C4 (eg maize) plants are more sensitive to drought and less sensitive to heat stress.
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