![]() Skim milk containing different concentration of casein micelles showed comparable light-scattering profiles a higher volume fraction of caseins led to the development of more elastic gels. The effect of different volume fractions of casein micelles and fat globules was investigated by observing changes in turbidity (1/l*), apparent radius, elastic modulus and mean square displacement (MSD), in addition to confocal imaging of the gels. The rennet-induced aggregation of skim milk recombined with whey protein-stabilized emulsion droplets was studied using diffusing wave spectroscopy (DSW) and small deformation rheology. Gaygadzhiev, Zafir Corredig, Milena Alexander, Marcela The impact of the concentration of casein micelles and whey protein-stabilized fat globules on the rennet-induced gelation of milk. ![]() Copyright © 2016 American Dairy Science Association. Rennet coagulation time and curd firmness were influenced by pregnancy stage, especially in the last weeks of gestation when milk had better coagulation characteristics this information should be accounted for to adjust test-day records in genetic evaluation of milk coagulation properties. For all traits, nonpregnant cows performed very similarly to cows in the first period of gestation. Milk production decreased and milk quality improved from the fourth month of pregnancy onward. Gestation stage significantly influenced all studied traits with the exception of somatic cell score. To better understand the effect of gestation on the aforementioned traits, each record was assigned to one of the following classes of pregnancy stage: (1) nonpregnant, (2) pregnant from 1 to 120d, (3) pregnant from 121 to 210d, and (4) pregnant from 211 to 310d. The traits analyzed were milk yield (kg/d), fat (%), protein (%), casein (%), and lactose (%) contents, pH, somatic cell score, rennet coagulation time (min), and curd firmness (mm). The data set included 25,729 records from 3,995 first-parity cows calving between August 2010 and August 2013 in 167 herds. The aim of this study was to investigate the effect of pregnancy stage on milk yield, composition traits, and milk coagulation properties in Italian Holstein cattle. Short communication: Effects of pregnancy on milk yield, composition traits, and coagulation properties of Holstein cows. ![]() The microstructure of RCM coagulum (âˆ❁1% casein), observed using transmission electron microscopy, confirmed that When less rennet was used, RCT increased in a linear inverse relationship without changes in relative G' or G″. Lowering pH of RCM from 6.6 to 6.2 resulted in reduced RCT from 11.9 to 6.5 min with increased relative G' after coagulation. After coagulation, relative G' was initially higher at the lower temperature with G' 1 of 3.6 Pa at 25Â☌ and 2.0 Pa at 31Â☌, but delayed in further development with G' 2 of 0.8 kPa at 25Â☌ and 1.1 kPa at 31Â☌. Lowering coagulation temperature from 31 to 25Â☌ increased G″ 0 by 6 fold and extended RCT from 7.4 to 9.5 min. ![]() When G' was measured relative to RCT (i.e., 1, 1.5, or 2 times RCT after RCT was reached, and expressed as G' 1, G' 1.5, and G' 2 ), log relationship was found between relative G' and casein level (R 2 > 0.94). The initial G″ (G″ 0 ) increased about 10-fold when casein levels were increased from 3.2 to 10.9%, whereas no change in initial G' (G' 0 ) was observed. Micellar P can be present as part of colloidal calcium phosphate (inorganic-P) or covalently bound to caseins as phosphate groups (casein-P). Ca and P are essential constituents of the micelles. The aim of this study was to ascertain relationships between milk characteristics and its rennet coagulation ability, focusing on the influence of calcium (Ca) and phosphorus (P). Despite the increasing number of studies, the causes for abnormal coagulation of milk are not fully understood. The main requirement for milk processed in most cheese typologies is its rennet coagulation ability. Malacarne, Massimo Franceschi, Piero Formaggioni, Paolo Sandri, Sandro Mariani, Primo Summer, Andrea Influence of micellar calcium and phosphorus on rennet coagulation properties of cows milk. ![]()
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