Whey Fermentation with Exopolysaccharide-Producing Lactic Acid Bacteria Modifies the Technological and Sensory Properties and Enhances the In Vitro Bioactivities of Requeson

Sweet whey can be valorized through fermentation and subsequent production of Requeson, a fresh whey cheese obtained by heat-induced protein precipitation. This study evaluated the physicochemical (moisture, water activity, protein, ash, chloride, and EPS content), textural (hardness, cohesiveness, adhesiveness, springiness, chewiness, and fracturability), sensory (overall liking and JAR saltiness), and in vitro bioactive characteristics of Requeson produced from sweet whey fermented with exopolysaccharide (EPS)-producing Lactobacillus delbrueckii subsp. bulgaricus NCFB 2772 and Streptococcus thermophilus SY-102, individually or in co-culture. Unfermented, citric-acid-acidified whey served as the control. The co-culture (FC) showed the highest EPS content (3.5 mg/g), higher moisture, lower hardness and fracturability, and greater springiness than the control. Consumer evaluation (n = 130) showed favorable acceptance of FC. Among FC formulations containing 0.5–1.5% NaCl, 0.5% NaCl yielded the highest overall liking, although it did not differ significantly from 1.0%. FC showed the highest DPPH radical-scavenging (22.76%) and ACE-I inhibitory (31.00%) activities. Overall, co-culture fermentation represents a potential strategy for producing value-added Requeson with modified technological and sensory properties and measurable in vitro bioactivities.