From discarded to delicacy: Valorization of sour jujube fruit pulp and peel into functional sucrose- and maltitol-based candies

Sour jujube fruit tissue (pulp and peel), a by-product of kernel processing, is rich in bioactive compounds but often discarded. This study valorized this waste by developing functional candied products using sucrose (ST) or maltitol (MT) as osmotic agents, comparing them against an untreated control (CK). Physicochemical, sensory, bioactive, and metabolic profiles were evaluated. Both osmotic processes dramatically reduced water activity ( a w ) from 0.92 (CK) to ∼0.65–0.68, enhancing shelf-life. While ST candy showed the highest sensory acceptability (score 7.5 vs. CK 3.2), MT candy demonstrated superior preservation of health-promoting compounds. Specifically, at day 21, MT candy retained significantly higher Vitamin C, total phenolics, and flavonoids compared to ST, while CK was almost completely depleted. Metabolomics revealed distinct metabolic reprogramming: ST showed massive sugar and procyanidin accumulation, while MT induced sugar alcohol buildup and selective enrichment of flavonoids (e.g., kaempferol) and phenolic acids. This indicates both sweeteners act as functional processing agents that modulate the phytochemical profile, with MT excelling in bioactive preservation. Thus, both sucrose- and maltitol-based candying offer viable strategies to transform sour jujube waste into functional food ingredients, with MT being particularly suitable for low-glycemic, antioxidant-rich products. • First valorization of sour jujube pulp into functional candied products. • Maltitol candy retains more bioactive metabolites than sucrose candy. • Metabolomics reveals maltitol upregulates flavonoid biosynthesis pathways. • Process transforms waste into a low-glycemic, antioxidant-rich functional food.