Thermal aging is an effective strategy for improving the functional properties of fruit-based ingredients via physicochemical modifications. This research investigates the effect of thermal aging on the physicochemical, antioxidant, and Maillard conjugation properties of dried lychee pulp aged at 50, 60, 70, and 80 °C for 20 days under controlled relative humidity. Comprehensive analyses were performed, including total phenolic content (TPC), total flavonoid content (TFC), individual phenolic profiles, saccharide composition, free amino acid content, degree of glycation (DG), peptide molecular weight distribution, and antioxidant activity assessed by ABTS, DPPH, and FRAP assays. The results demonstrated that aging at moderate temperatures (60–70 °C) significantly enhanced TPC, TFC, and antioxidant activity, alongside an increased degree of glycation, peaking at approximately 47% at 70 °C. Principal component analysis (PCA) confirmed strong correlations between these compositional changes and antioxidant responses. In contrast, aging at 80 °C led to the degradation of thermolabile phenolics, sugars, and amino acids, resulting in reduced antioxidant activity compared with non-aged samples. Overall, the results highlight a temperature-dependent balance between constructive Maillard conjugation and thermal degradation, identifying 60–70 °C as an optimal aging range for improving the functional quality of dried lychee pulp. These findings provide mechanistic insight into thermal modulation of fruit bioactivity and support the potential application of controlled thermal aging in the development of value-added functional food ingredients.

Honeybee brood is a nutrient-rich food source containing natural umami-active compounds, such as glutamic acid, aspartic acid, and 5′-nucleotides, which are responsible for its characteristic umami taste. This study aimed to optimize drying conditions to enhance the umami composition and sensory properties of honeybee brood umami powder (HBb-UP). A factorial design was employed to evaluate the effects of drying temperature and time on umami-related amino acids, 5′-nucleotides, and equivalent umami concentration (EUC). Drying temperature and time significantly influenced the formation of umami compounds, with the optimized drying condition (65 °C for 3 h) promoting higher umami composition and improved sensory attributes of HBb-UP. Volatile flavor analysis using GC–MS and an electronic nose revealed a diverse range of aroma compounds contributing to the overall flavor profile. Descriptive sensory evaluation and electronic tongue analysis indicated that umami and saltiness were the dominant taste attributes, accompanied by mild seasoning and fishy notes associated with interactions between amino acids and nucleotides. Principal component analysis demonstrated positive correlations among umami-related amino acids, nucleotides, EUC, and sensory attributes, confirming their combined contribution to taste perception. These findings highlight the potential of optimized HBb-UP as a natural flavor enhancer and functional ingredient for use in sustainable food systems.

The development of functional ingredients from perishable tropical fruits supports sustainable food systems by reducing postharvest losses while retaining bioactive compounds. This study developed and optimized black lychee (Litchi chinensis Sonn.) extracted powder (BLEP) by spray drying and evaluated its physicochemical characteristics and antioxidant stability during storage. A 2² factorial design was employed to investigate the effects of maltodextrin concentration (5–30%) and inlet temperature (160–200 °C). Graphical optimization using an overlay plot identified 17.80% maltodextrin and an inlet temperature of 200 °C as the best compromise among the significant responses within the range tested. The optimized BLEP contained vanillic acid and epicatechin as the predominant phenolic compounds together with essential amino acids, including leucine. Degree of glycation (DG) and HMF were measured as indirect indicators of Maillard reaction progress. Over six months at 4, 25, 35, and 45 °C, color parameters, DG, and HMF remained stable, whereas total phenolic content (TPC) declined from 437.11 to 225–252 mg GAE/100 g db and ABTS radical scavenging activity declined progressively. TPC was strongly associated with antioxidant capacity (r = 0.914 with ABTS, p < 0.01), and its degradation followed zero-order kinetics (adjusted R² = 0.931–0.971) with a predicted half-life (L₅₀) of 199–220 days. The optimized powder therefore showed good physical and chromatic stability with partial loss of antioxidant-related compounds over time.