Physicochemical and microbiological evaluation of concentrated whey obtained by reverse osmosis

Abstract

The processing of milk during cheese making generates a large amount of whey. This by product can be considered raw material in the food industry and especially in agro industrial products where it may be used to complement and supplement food. In this context, we evaluated the stability and physicochemical and microbiological aspects of concentrated whey obtained by reverse osmosis of dairy waste from mozzarella processing. We collected whey samples from different stages of processing, such as pasteurized whey, silo-stored whey, concentrated whey and water-permeated whey. The Standard Methods for the Examination of Dairy Products was employed and the following parameters were analyzed: temperature, titratable acidity (ºD), ºBRIX, density, total dry extract, total fat, pH, total coliform, thermotolerant coliform and mesophilic aerobic microorganisms. Mesophilic microorganisms were observed in all samples. However, the mesophilic count in treated whey by reverse osmosis was below the reference value (1x105 CFU mL-1). The concentrated whey had a temperature of above 8 ºC, titratable acidity of 22 ºD, around 18 ºBRIX of soluble solids, density equals to 1085 g cm-3, percentage of total solids of 30.0% and pH of 6.4. The concentrated whey had less than 4% fat. It could be observed that the concentrated whey is a product with high nutritional value and microbiological stability when immediately subjected to reverse osmosis. Consequently, the concentrated whey obtained and evaluated in this investigation presents technical and sanitary characteristics for human consumption.