Proteolysis and Storage Stability of Ultra High Temperature Processed Milk as Influenced by Somatic Cell Count and Bacterial Count

Abstract

Hachana, Y . and Krai'em, K. 2009. Proteolysis and storage stability of ultra high temperature processed milk as influenced by somatic cell count and bacterial count. J. Appl. Anim. Res., 36: 65-70.To study keeping quality of UHTprocessed 1.5% fat milk of different somatic cell count (SCC) and bacterial count (BC), that would be sufficient to produce an off-flavor, a 180 days experiment was conducted. Sixty eight per cent ofpanelists detected off-flavor related to proteolysis, when the decrease in casein as a percentage of true protein (CN/ TP) was > 5%. UHT milk produced from low SCC milk (50,000 cells m1-I) and low bacterial count (<lo5 cfu m1-I) maintained high organoleptic quality for the entire 180 days shelf-life period. UHT milk produced from milk with high SCC (740,000 and 1,102,000 cells m1-l) developed an ofFflavor at about 90 and 60 days, respectively. Off-flavor was detected at 30 days storage when BC was high in raw milk (>2xl06 c f i ml-l). It was concluded that initial somatic cell and bacterial counts of UHT milk determined its keeping quality.

Effects of addition of somatic cells to caprine milk on cheese quality

“…Marino et al (2005) reported that proteolysis during ripening of cheese increased with addition of somatic cells, although this effect was reduced by pas teurisation after cell addition. A relationship between proteolysis in milk and SCC was described by Hachana and Kraiem (2009).…”