Upcycling Wheat-Rye Bread and Chokeberry Waste into Sustainable Fermented Beverages with Potential Probiotic Properties

Increasing food consumption and waste generation are today's most difficult economic and environmental challenges. In line with the sustainable production and consumption concept, wasted food, as a source of valuable resources, can be reused to produce new products of higher value than the raw materials from which they were made. This concept was used in this work to design products that are a plant-based alternative to fermented milk drinks, which arouse great interest among consumers due to their health-promoting properties. This study aimed to design potential probiotic beverages from food industry waste, including wheat-rye bread and chokeberry pomace, using lactic acid fermentation with different strains of lactic acid bacteria (LAB) and to evaluate selected quality features of the obtained beverages. In the first stage of the research, the group of LAB strains was tested for their efficiency in bakery waste fermentation, and then the potential probiotic properties of chosen LAB strains (Lactiplantibacillus plantarum A7, Lacticaseibacillus paracasei INV001, Lacticaseibacillus rhamnosus INV002, Lentilactobacillus buchneri P7, Loigolactobacillus coryniformis INV014) were characterized according to FAO/WHO requirements. For the prepared beverages, microbiological quality, antioxidant properties, and the content of polyphenolic compounds were determined. It was found that bakery and chokeberry waste may constitute a good base for obtaining fermented beverages with some beneficial properties, including a high number of potentially probiotic bacteria, reaching 108 CFU/mL, and antioxidant properties, which positively verified their functional properties. The research confirms the high potential of lactic acid fermentation in managing food waste to create innovative, sustainable food products with probiotic properties.