EFFECT OF DIFFERENT PROCESSING TECHNIQUES ON BUFFALO WHEY PROTEINS

Abstract

Whey, a byproduct of cheese industry is generally discarded due to lack of expertise to convert it into various products in Pakistan. As a dairy effluent its COB and BOD values is 60 to 80 and 30 to 50 g/L respectively due to a high organic load. In the present investigation, a little effort is being carried out to pasteurize (by LTLT and HTST process), concentrate (38 & 48%) and convert it into powder (dried at 160 and 180°C) to conserve and increase the shelf life of whey, which later on can be used in different products. The use of membrane filtration to transform the whey into concentrate was not considered in this study because of its unavailability in Pakistan. The impact of selected processing techniques on the whey attributes was studied through various physicochemical, SDS-PAGE and RP-HPLC analysis. The pasteurized and concentrated whey samples were stored at low temperatures (4°C for pasteurized whey and 4°C, -20°C for concentrated) for the period of 7 and 60 days respectively. The powder samples after vacuum packaging were stored at room temperature for 6 months. The analysis showed that the raw whey contained fat (0.3%), protein (0.76%), NPN (0.15%), lactose (4.76%), total solids (6.2%) and ash (0.43%) contents. From the results of pasteurization, it was concluded that LTLT is the better option for whey pasteurization considering the protein denaturation through NPN, SDS and RP-HPLC studies. The concentrated whey (CW) samples showed the increase in acidity (0.22%), NPN (0.116%) and decrease in pH (0.9), fat (0.05%), protein (0.018%), lactose (7.37%), total solids (3.37%) during 60 days storage period. The viscosity of CW increased (640 to 654cP) during storage. The SDS-PAGE chromatogram and RP-HPLC profile of CW showed the 54% denaturation level in α-Lb and 61-84% in β-Lg. For the whey powder (WP) production, CW @ 48% was used and dried by the spray drying process at two (160 and 180°C) inlet temperatures. It was found that moisture content of whey powder increased 4.11 to 5.22%, acidity from 2.30 to 2.50%, lactose content decreased from 66 to 61%, NPN increased (0.14%), foam stability decreased (0.52) mL, turbidity increased from 54 to 63% in WP for samples dried at 160°C and 65 to 75% at 180°C. WPNI of whey sample was in the range 4 to 5mg/g. SDS-PAGE indicated the dimmer and aggregate formation near 36 kDa and 70kDa bands due to protein denaturation. The intensity of these bands increased with the temperature and storage period. The RP-HPLC profile indicated that βLg denatured up to 94% at 160°C and 52% at 180°C. The native structure of BSA and CMP was less affected by spray drying. It is concluded from the present effort that the LTLT and concentration at 48% are better the production of pasteurized and concentrated whey. Regarding the condition for the production of powder, the 160°C is the good option for getting the powder with good foaming capacity, turbidity, and solubility point of view; however for the foam stability and other properties 180°C would be the preferred temperature.