Improving Functional Properties of Not‐From‐Concentrate Apple Juices Through Probiotic Fermentation as Enhancer of Bioactivity and Phenolic Stability

The growing demand for non-dairy functional foods makes probiotic-enriched apple juice-a lactose-free, polyphenol-rich alternative-an attractive product aligned with contemporary health trends, representing a significant market opportunity for juice industries. This study evaluated the feasibility of using two commercial Not-From-Concentrate (NFC) apple juices (AJ1, AJ2) as a matrix for four probiotic strains (Lacticaseibacillus casei ATCC 393, Lacticaseibacillus rhamnosus ATCC 53103, Lactobacillus acidophilus ATCC 314, Lactiplantibacillus plantarum ATCC 8014) over four weeks of refrigerated storage. The study monitored bacterial viability, (poly)phenolic content, antioxidant capacity (DPPH, ABTS, FRAP), and anti-inflammatory activity (LOX inhibition). Despite a shared origin, the juices exhibited significant initial differences in phenolic profile (primarily rutin, hydrocaffeic, and caffeic acid) and antioxidant activity, underscoring the impact of specific industrial processing. Probiotic survival was juice-dependent, with higher viability in AJ2 (89%-100%) than in AJ1 (72%-87%), though both were effective carriers. Phenolic losses were minimal (<20%) and not probiotic-dependent. Antioxidant capacity remained stable (AJ1) or increased post-fermentation (AJ2), with AJ2 exhibiting 100%-300% greater scavenging activity. Furthermore, probiotic enrichment significantly enhanced functional properties, including elevated anti-inflammatory activity that persisted. Correlation analysis revealed positive relationships between LOX inhibition and specific phenolics, particularly hydroxycaffeic acid, chlorogenic acid, and total polyphenols. These findings confirm that industrial NFC apple juices are robust carriers for diverse probiotics. The inherent variability of industrial processes allows for the design of tailored functional beverages that synergistically combine natural bioactives with probiotics, enabling strategic product diversification. PRACTICAL APPLICATIONS: This study supports the use of cloudy apple juices, such as Not-From-Concentrate (NFC), as a base for developing non-dairy functional beverages with probiotics and natural polyphenols. The proposed formulations demonstrated good microbial viability, antioxidant stability, and enhanced anti-inflammatory activity during storage through strain-polyphenol synergy. Importantly, by focusing on industrially produced NFC juices, the results capture real-world variability often overlooked in laboratory-scale studies, strengthening their translational potential for the beverage industry. These findings offer a promising alternative to expand access to health-promoting products, meet the growing market demand for plant-based functional foods, and deliver novel value-added products with clear commercial feasibility.