Controlling psychrotrophic bacteria in raw buffalo milk preserved at 4 °C with esterified legume proteins

The activity of native and esterified legume proteins in controlling the growth of psychrotrophic bacteria contaminating raw buffalo milk kept at 4 degrees C as well as milk quality was followed and assessed. Supplementation of milk samples with 0.5% of methylated legume proteins has considerably reduced the levels of total bacterial count (TBC), psychrotrophic bacteria count (PBC) and Pseudomonas spp. count (PSC), during cold preservation. Raw buffalo milk samples supplemented with esterified legume proteins have reached a TBC log of 5.1-5.3 cfu ml(-1) surpassing the spoilage level after a relatively longer period (6 days) than in the case of non-supplemented raw milk (2 days). At the end of storage period, acidity level reached comparatively higher maximum values in the untreated raw milk (0.74 +/- 0.018) compared to lower values in case of milk supplemented with esterified legume proteins (0.52 +/- 0.011 to 0.55 +/- 0.012). At the same time corresponding pH values of the untreated raw milk attained a lower minimum values in case of raw milk supplemented with esterified legume proteins than in non-treated raw milk. Some casein degradation started in non-treated raw milk after 2 days of preservation at 4 degrees C and complete casein degradation was observed after 4 days. Casein remained nearly intact in raw milk supplemented with esterified proteins for 10 days. Supplementation with esterified legume proteins has substantially delayed the coagulation response to the 8 and 10 days of preservation at 4 degrees C, instead of 4 days in case of the control. (C) 2011 Elsevier Ltd. All rights reserved.