Enzymatic Synthesis of Galacto-Oligosaccharides from Concentrated Sweet Whey Permeate and Its Application in a Dairy Product

Valorization of by-products in the dairy industry as a strategy to promote circular economies has become a priority around the globe. Cheese whey and its derivates from filtration technologies offer a source of valuable molecules such as proteins, fat, lactose, and minerals. For this study, after protein concentration and recovery through ultrafiltration, lactose remaining in the permeate was furtherly concentrated with nanofiltration, resulting in a retentate used as substrate for the enzymatic production of galacto-oligosaccharides (GOS). The kinetics of GOS generation with a commercial β-galactosidase, was carried out, quantifying the carbohydrate composition by HPAEC-PAD. Results showed that at 0.5 h, GOS yield reached a maximum of 74% (g GOS/g lactose) with a lactose utilization of 63%. Under these conditions, a GOS syrup (75% soluble solids) was generated and applied in a porridge for blind paired comparison test, including a control without the syrup. No differences were identified in color and odor between porridges; however, flavor and mouthfeel of the GOS-added sample improved according to the comments of panelists. This study presents an alternative process for the valorization of whey permeate to produce GOS ingredients that can be used directly in day-to-day dairy products.