Influence of concentration of milk solids on the dissociation of micellar κ-casein on heating reconstituted milk at 120°C

1991 ◽  
Vol 58 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Harjinder Singh ◽  
Lawrence K. Creamer
Keyword(s):  
Gel Electrophoresis ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Heating Time ◽  
Total Solids ◽  
Solids Content ◽  
Milk Solids ◽  
Reconstituted Milk

SummarySkim milks were prepared from skim milk powder at several concentrations between 10 and 25% total solids and portions were pH-adjusted to between pH 6·3 and 7·1 and heated at 120°C. After ultracentrifugation (88000 g for 90 min), the supernatants were analysed using gel electrophoresis to determine the concentrations of β-lactoglobulin, α-lactalbumin and κ-casein. The dissociation of κ-casein from the micelles was dependent on both the pH and the total solids content of milk before heating. Both higher pH (in the range 6·5–7·l) and higher concentration increased the extent of dissociation. A further series of samples were heated for 2–11 min at 120°C at pH 6·55. κ-Casein dissociation increased with concentration and with heating time. It was concluded that as the milk increased in concentration, the pH at which micellar κ-casein dissociated on heating was lowered.

scholarly journals Effect of total solids standardization using different methods on mineral content of yoghurt

Mljekarstvo ◽  
2021 ◽  
Vol 71 (2) ◽  
pp. 103-111
Author(s):  
Firuze Ergin ◽  
Keyword(s):  
Mineral Content ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Vacuum Evaporation ◽  
Mineral Contents ◽  
Total Solids ◽  
Technological Processing ◽  
Solids Content

Yoghurt is a good dietary source of macro and micro minerals. However, the mineral content of yoghurt can vary according to the technological processing used in its manufacture. In this context, the aim of this study was to compare some macro (Ca, K and Mg) and micro (As, Cd, Co, Fe, Mn, Ni, Pb, Se, V and Zn) mineral contents of total solids-standardized yoghurts with four different methods by following: (1) Addition of skim milk powder to milk, (2) Concentration of yoghurt milk by vacuum evaporation, (3) Concentration of yoghurt curd in a cloth bag and (4) Concentration of yoghurt curd by mechanical centrifugation. The highest content of the macro minerals was in the yoghurt produced with method 1, while the highest content of most of the micro minerals was in the yoghurt produced with method 4. The results of this study showed that the mineral content of yoghurt could be modified by the method used in the manufacture of yoghurt to standardize total solids content.

Thermal Resistance of Listeria monocytogenes Scott A in Ultrafiltered Milk as Related to the Effect of Different Milk Components

2010 ◽  
Vol 73 (11) ◽  
pp. 2110-2115 ◽  
Author(s):  
KINGA SZLACHTA ◽  
SUSANNE E. KELLER ◽  
ARLETTE SHAZER ◽  
STUART CHIRTEL
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Milk Fat ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Single Measure ◽  
Total Solids ◽  
Whole Milk ◽  
Milk Components

Pasteurization parameters for grade A milk are well established and set by regulation. However, as solids levels increase, an increased amount of heat is required to destroy any pathogens present. This effect is not well characterized. In this work, the effect of increased dairy solids levels on the thermal resistance of Listeria monocytogenes was examined through the use of ultrafiltered (UF) milk, reconstituted milk powder, and the milk components lactose and caseinate. From the results obtained, lactose and caseinate did not appear to affect thermal resistance. In addition, the level of milk fat, up to 10% of the total solids in UF whole milk, did not result in statistically significant changes to thermal resistance when compared with UF skim milk. Reconstituted skim milk powder at 27% total solids (D62-value = 1.16 ± 0.2 [SD] min, z = 5.7) did result in increased thermal resistance, as compared with reconstituted skim milk powder at 17.5% (D62-value = 0.86 ± 0.02 min, z = 5.57) and UF whole milk at 27% total solids (D62-value = 0.66 ± 0.07 min, z = 5.16). However, that increase appeared to be due to the increase in salt levels, not to increases in caseinate, fat, or lactose. Consequently, total solids, as a single measure, could not be used to predict increased thermal resistance of L. monocytogenes in concentrated milk.

Defining Optimal Conditions for Making Cottage Cheese from Reconstituted Milk Powder

1983 ◽  
Vol 46 (8) ◽  
pp. 686-689 ◽  
Author(s):  
C. H. WHITE ◽  
J. M. RYAN
Keyword(s):  
Pilot Plant ◽  
Setting Time ◽  
Milk Powder ◽  
Skim Milk ◽  
Cottage Cheese ◽  
Quality Factors ◽  
Total Solids ◽  
Holding Period ◽  
Reconstituted Milk ◽  
Pilot Plant Study

Cottage cheese was manufactured from milk powder reconstituted at solids levels ranging from 8.0 to 20%. The reconstituted cheese milk was held at 6°C for four time periods (0, 12, 24 and 36 h), followed by inoculation with 1 % bulk lactic starter. Values determined were yields expressed in three different ways and total solids. The study was first conducted in the laboratory using 3-L containers for each treatment effect. This was to be used as a screening technique with the optimal results then being tested under pilot plant conditions. The 0-hold resulted in a shorter setting time than any of the other hold periods. The four optimal solids levels obtained in the laboratory study were determined on the basis of moisture characteristics, yield, cost and setting time. Those solids levels evaluated in the pilot plant study were 10.5, 12, 13 and 15%. Two hold times were selected for the pilot plant study, with those being a 0-hold and a 12-h hold at 4.4°C. All results were compared to two controls, a non-fortified (9.0% total solids) and a fortified (10.5% total solids) skim milk. Cost comparisons at the various levels were made. Over all conditions of this study, cottage cheese made from 10.5% reconstituted non-fat-dry milk with a 0-hold appeared to be best as measured by moisture control, set time, cost, adjusted yield and appearance of curd at varying stages. In the pilot plant study, there was no significant (P<0.05) difference in any measurable parameter between the 0- and 12-h holding period. There was very little difference between the 10.5 and 12.0% cheese, except for price (12% cheese would cost 2 to 3% more per pound of dry curd than 10.5% cheese) and appearance of the curd (10.5% curd was slightly less matted with fewer “fines”). Work is presently underway to study creaming factors of this cheese. The two control cheeses were approximately the same as the 10.5% reconstituted skim milk cheese with regard to quality factors but were cheaper (about 10¢/.454 kg dry curd).

Yogurt production from reconstituted skim milk powders using different polymer and non-polymer forming starter cultures

1993 ◽  
Vol 60 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Carmen Wacher-Rodarte ◽  
Marcia V. Galvan ◽  
Amelia Farres ◽  
Francisco Gallardo ◽  
Valerie M. E. Marshall ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Skim Milk ◽  
Starter Cultures ◽  
Synergic Effect ◽  
Total Solids ◽  
Total Milk ◽  
Solids Content ◽  
Milk Solids ◽  
Viscosity Polymer

SummaryUsing polymer producing (ropy) strains of lactic acid bacteria it was possible to reduce considerably the syneresis of yogurt, even with 12% total milk solids. The viscosities obtained with these strains were also similar to those obtained using normal strains and milk with 17% total solids content. The concentration of milk and the polymer produced by ropy starters had a synergic effect in increasing viscosity. Polymer production was not affected in most cases by milk concentration. One type of ropy culture (Wiesby) seemed to produce a different kind of polymer as it could not be determined by alcohol precipitation, in spite of being able to reduce syneresis and increase viscosity in yogurt. A limited number of yogurts were evaluated organoleptically, one prepared with a ropy starter strain (NCFB at 12, 14·5 and 17% total solids) and one prepared with a non-ropy strain (LL-I at 17% total solids). The results suggest that the ropy strain yogurts had different mouthfeel from the non-ropy strain yogurts; the most acceptable product overall was the ropy strain made with 12% total solids.

QUALITY OF PROTEIN IN MILK REPLACERS FOR YOUNG CALVES. IV. RENNET (CHYMOSIN, RENNIN) COAGULATION OF RECONSTITUTED SKIM MILK POWDER CONTAINING ADDED PROTEINS, FAT, CALCIUM, PHOSPHATE AND CITRATE

1976 ◽  
Vol 56 (2) ◽  
pp. 339-345 ◽  
Author(s):  
D. B. EMMONS ◽  
J. D. JONES ◽  
E. E. LISTER
Keyword(s):  
Soy Protein Isolate ◽  
Milk Powder ◽  
Skim Milk ◽  
High Heat ◽  
Skim Milk Powder ◽  
Protein Isolate ◽  
Active Principle ◽  
Total Solids ◽  
Ph Values ◽  
Milk Replacers

The effects of added nutrient sources on curd firmness of reconstituted skim milk powder (10% total solids) were studied. Defatted rapeseed flour (4%) had little effect whereas whey powder (4%) and fish protein concentrate (2%) decreased gel strength of the reconstituted skim milk by approximately 30%. Soybean meal (4%) and soy protein isolate (2%) markedly reduced curd firmness; addition of CaCl2 restored coagulability and curd firmness. However, addition of CaCl2 did not restore gel firmness in reconstituted, severely heated skim milk powder to that of a low-temperature product. Addition of 0.1% CaCl2 slightly increased firmness of reconstituted low- and high-heat powder at pH 6.1; further addition to 0.4% CaCl2 decreased firmness slightly. It appears that when there is sufficient available Ca, further additions have no effect on curd firmness. The results indicate that milk replacers which coagulate with rennet (containing chymosin or rennin as active principle) can probably be produced even when some of the skim milk protein is replaced by other less expensive proteins. Addition of citrate (14 mM), followed by adjustment of the pH, prevented coagulation at pH 6.1 and markedly reduced firmness at pH 5.6 and 5.2. Addition of citrate at 5.7 mM did not prevent coagulation at those pH values. Addition of phosphate had little effect on curd firmness at these pH values. Addition of fat to skim milk containing 15 or 20% total solids, followed by homogenization, had little effect on curd firmness at pH 6.1. Fat additions, however, decreased curd firmness of skim milk containing 10% total solids and nearly prevented coagulation in skim milk containing 5% total solids.

SOME IN VITRO OBSERVATIONS ON FACTORS AFFECTING RENNET (CHYMOSIN) CLOTTING OF CALF MILK REPLACERS

1981 ◽  
Vol 61 (2) ◽  
pp. 393-401 ◽  
Author(s):  
K. J. JENKINS ◽  
J. R. LESSARD ◽  
D. B. EMMONS
Keyword(s):  
Milk Powder ◽  
Skim Milk ◽  
Total Solid ◽  
Skim Milk Powder ◽  
Factors Affecting ◽  
Total Solids ◽  
Rennet Coagulation ◽  
High Concentrations ◽  
Milk Replacers

The formation of a firm rennet (chymosin) curd in the abomasum appears to have a useful physiological function in the newborn calf. The results of in vitro experiments with calf milk replacers conducted to study the effect of various factors on rennet clot formation demonstrated that low-pressure (L) dispersion of lipid into skim milk powder replacers resulted in markedly higher (P < 0.05) curd firmness values with rennet than homogenization (H) at all total solid (10, 15 and 20%) and lipid (10, 20, 30 and 40% TS) levels tested. At higher total solids levels, curd firmness, clot weight and percentage of replacer lipid in clot were significantly (P < 0.05) increased. The L dispersion method also promoted rennet coagulation and firmer curds than H when skim was partially replaced by mixtures offish protein-whey or Promine D-whey. The results indicate that reconstitution of milk replacers at high total solids levels (e.g., 20%), in conjunction with L dispersion of lipid, would be beneficial for promoting rennet coagulation, curd firmness and high concentrations of protein and lipid in the clot.

Denaturation, aggregation and heat stability of milk protein during the manufacture of skim milk powder

1991 ◽  
Vol 58 (3) ◽  
pp. 269-283 ◽  
Author(s):  
Harjinder Singh ◽  
Lawrence K. Creamer
Keyword(s):  
Spray Drying ◽  
Milk Powder ◽  
Skim Milk ◽  
Heat Stability ◽  
Skim Milk Powder ◽  
Casein Micelle ◽  
Commercial Plant ◽  
Preheat Treatment ◽  
Solids Content ◽  
Time Required

SummaryThe effect of preheat treatment, evaporation and drying in a commercial plant on the denaturation of βlactoglobulin and α-lactalbumin, their incorporation into the casein micelle and the heat stability characteristics of the milks and powders were determined. Preheat treatments between 110 °C for 2 min and 120 °C for 3 min denatured between 80 and 91% of β-lactoglobulin and between 33 and 45% of α-lactalbumin. Evaporation increased the extent of denaturation but spray drying did not increase it further. The incorporation of α-lactalbumin and βlactoglobulin into the micelles was markedly less than the amount that denatured and was not a constant ratio to it. Heat coagulation times at 140 °C of milks, concentrates and powders diluted to the original milk concentration were measured as a function of pH. In general, the greater the collective heat treatment, the shorter the time required to achieve coagulation. Spray drying shifted the peak positions in the pH-heat coagulation time profiles. In contrast, heat coagulation times (measured at 120 °C) of concentrates and powders diluted to 20% total solids content increased with the severity of the preheat treatment. Surprisingly, spray drying markedly increased the heat coagulation times of the diluted concentrates.

Influence of the emulsion droplet type on the rheological characteristics and microstructure of rennet gels from reconstituted milk

2009 ◽  
Vol 76 (3) ◽  
pp. 349-355 ◽  
Author(s):  
Zafir Gaygadzhiev ◽  
Arthur Hill ◽  
Milena Corredig
Keyword(s):  
Elastic Modulus ◽  
Milk Fat ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Tween 20 ◽  
Gel Structure ◽  
Ionic Equilibrium ◽  
Fat Globules ◽  
Reconstituted Milk

Rheological and microstructural properties of rennet-induced milk gels containing different fat globules were studied. Recombined milks were prepared by mixing reconstituted low-heat skim milk powder and anhydrous milk fat emulsified with reconstituted skim milk powder (SMP), sodium caseinate (NaCas), whey protein isolate (WPI) or Tween 20. Final elastic modulus of the rennet gels containing WPI- or Tween 20-stabilized fat globules showed significantly lower values compared with those prepared with SMP-emulsified fat globules. SMP-stabilized fat globules interacted with the continuous casein network reinforcing the gel structure. Confocal micrographs supported the rheological data revealing that gels containing SMP-stabilized fat globules formed a tighter network relative to other treatments. Microscopy images also showed some degree of droplet flocculation in the case of gels containing WPI- or Tween 20-stabilized fat globules, and this was most likely the cause of the increase of elastic modulus of these systems. Contrary to reports for acid-induced casein gels, NaCas-stabilized fat globules hindered the formation of rennet gels. These results illustrate that rennet gel structure is affected by droplet-droplet and droplet-casein interactions, which in turn are determined by the composition of the oil-water interface as well as the ionic equilibrium in the reconstituted milk gels.

Kinematic viscosities of New Zealand skim-milk

1978 ◽  
Vol 45 (1) ◽  
pp. 25-35 ◽  
Author(s):  
J. H. Buckingham
Keyword(s):  
New Zealand ◽  
Seasonal Variations ◽  
Kinematic Viscosity ◽  
Milk Powder ◽  
Skim Milk ◽  
Skim Milk Powder ◽  
Total Solids ◽  
Solids Concentration ◽  
Powder Manufacture ◽  
Single Batch

SummaryThe variation in kinematic viscosity (ν) with solids concentration and temperature has been determined for native skim-milk concentrates and reconstituted New Zealand skim-milk. Below 40% (w/v) total solids, samples reconstituted from a single batch of skim-milk powder model the behaviour of native concentrates obtained from an evaporation plant at all times of the year. Above 40% (w/v) agethickening and seasonal variations in the viscosity of native concentrates become significant. Age-thickening can be reduced by cooling the concentrate. These results are discussed in relation to milk powder manufacture.

A laboratory study of continuous fermentation of skim-milk for the production of sour curd cheese

1971 ◽  
Vol 38 (2) ◽  
pp. 137-144 ◽  
Author(s):  
P. M. Linklater ◽  
C. J. Griffin
Keyword(s):  
Continuous Fermentation ◽  
Plug Flow ◽  
Milk Powder ◽  
Skim Milk ◽  
Fermented Milk ◽  
Skim Milk Powder ◽  
Fresh Milk ◽  
Batch Fermenter ◽  
Total Residence Time ◽  
Reconstituted Milk

SummaryThe feasibility of 2-stage continuous fermentation of skim-milk to produce sour curd cheese (quarg) has been established. The first stage was a stirred pH-stat fermenter, operated at pH 5·4, 5·6, 5·8 and 6·0, in which the operating pH was maintained by inflowing fresh milk. The remaining fermentation down to pH 4·7 was carried out by a procedure which simulated a second-stage plug flow fermenter (i.e. one in which forward velocity was as constant as possible at all points of the crosssection).Skim-milk powder was dissolved to give 8, 10, 14 and 20% solids in the reconstituted milk. Maximum productivity of fermented milk solids was obtained with reconstituted milk containing 20% solids and operation of the first-stage fermenter at pH 5·4. This 2-stage continuous fermentation gave a total residence time of about 5 h, which represents a rate of production 4·8 times that obtainable in 24 h in a batch fermenter of the same fluid capacity filled once daily with the same reconstituted milk.

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