engleski

Quality of cow and goat acidophilus milk during storage

The influence of different heat treatment (85 ?C during 20 min, and 90 ?C during 10 min) and amount of demineralized whey powder added to milk (0.5%, 1.0%, 1.5% and 2.0%) prior heat treatment, on the acid milk sera nitrogen content and nitrogen matter distribution from milk to sera have been investigated. Reconstituted skim milk with 8.5% NFDM (nonfat-dry matter) was standardized with 0.5%, 1.0%, 1.5% and 2.0% demineralized whey powder (DWP), respectively. The amount of nitrogen content was 0.4780% for milk with 8.5% NFDM, and linearly increased to 0.4596%, 0.5067%, 0.5151% and 0.5245% for milk with added 0.5%, 1.0%, 1.5% and 2.0% DWP, respectively. The amount of milk nitrogen content decreased after heat treatment. After acid precipitation of casein or co-aggregates formed during heat treatment, curd was separated by self-pressing during 60 min. Sera nitrogen content from heat untreated milk increased from 0.0729% (milk with 8.5% NFDM) to 0.0788%, 0.0852%, 0.0902% and 0.0982% respectively for milk with 0.5%, 1.0%, 1.5% and 2.0% added DWP. Sera nitrogen content from milk treated at 85 ?C during 20 min increased from 0.0433% to 0.0479%, 0.0521%, 0.0535% and 0.0570% respectively for milk with 0.5%, 1.0%, 1.5% and 2.0% added DWP. Sera nitrogen content from milk treated at 90 ?C during 10 min had approximate value, 0.0429%, 0.0474%, 0.0536%, 0.0527% and 0.0567%, respectively for milk with 8.5% NFDM and milk with 0.5%, 1.0%, 1.5% and 2.0% added DWP. Distribution of nitrogen matter from milk to sera increased with increasing of added DWP amount, for both untreated and heat-treated milk. Distribution of nitrogen matter from untreated milk with 8.5% NFDM to sera was 12.47%, and increased to 12.85%, 13.49%, 13.61% and 14.88% for untreated milk with added 0.5%, 1.0%, 1.5% and 2.0% DWP, respectively. Distribution of nitrogen matter from heat-treated milk to sera was significantly lower; for milk treated at 85 ?C during 20 min distribution of nitrogen matter was 7.33%, 7.91%, 8.28%, 8.14% and 8.57% for milk with 8.5% NFDM and milk with added 0.5%, 1.0%, 1.5% and 2.0% DWP, respectively. Distribution of nitrogen matter from milk treated at 90 ?C during 10 min to sera was 7.39%, 7.84%, 8.51% 7.91% and 8.43% for milk with 8.5% NFDM and milk with added 0.5%, 1.0%, 1.5% and 2.0% DWP, respectively. As indicated in result for nitrogen matter distribution, over 91% milk nitrogen matter was utilised by production of co-precipitates even if 2.0% DWP was added. It could be concluded that heat treatments at 85 ?C during 20 min and 90 ?C during 10 min, don't give significantly different distribution of nitrogen matter, as well as that almost all whey proteins from DWP coaggregate with casein from milk.

nije evidentirano

nije evidentirano