No Waste from Waste: Membrane-Based Fractionation of Second Cheese Whey for Potential Nutraceutical and Cosmeceutical Applications, and as Renewable Substrate for Fermentation Processes Development

Second cheese whey (SCW) derived from buffalo milk is the main by-product of the mozzarella cheese dairy industry. The objective of this study was to develop a membrane-based purification procedure to obtain specific fractions from SCW and assess their biological and applicative potential. Special interest was paid to the proteins and newly identified health-promoting compounds that could be recovered and used as value-added products in different sectors of food and pharmaceutical industries. SCW has been treated, sequentially, with microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF) membranes giving the possibility to obtain three different fractions, namely retentates recovered on 100 and 10 kDa (R100 and R10) and a nanofiltration retentate (RNF). These retentates were compared for their ability to preserve human keratinocytes from dehydration, to form protein-based films by casting, and finally they were used for probiotic cultivations as the main substrate. Results showed that Lactobacillus rhamnosus could grow without any further additional nutrient up to 2.2 ± 0.3 × 109 CFU/mL in the RNF medium. Dehydration tests on HaCat cells proved R100 as the most efficient fraction in preserving cell viability from this specific stress. R10, after diafiltrations, formed transparent films with improved features when glycerol was added as a plasticizer.