The change in phenols, polysaccharides and volatile profiles of noni juice from laboratory- and factory-scale fermentation was analyzed during a 63-day fermentation process. The phenol and polysaccharide contents and aroma characteristics clearly changed according to fermentation scale and time conditions. The flavonoid content in noni juice gradually increased with fermentation. Seventy-three volatile compounds were identified by solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC-MS). Methyl hexanoate, 3-methyl-3-buten-1-ol, octanoic acid, hexanoic acid and 2-heptanone were found to be the main aroma components of fresh and fermented noni juice. A decrease in octanoic acid and hexanoic acid contents resulted in the less pungent aroma in noni juice from factory-scale fermentation. The results of principal component analysis of the electronic nose suggested that the difference in nitrogen oxide, alkanes, alcohols, and aromatic and sulfur compounds, contributed to the discrimination of noni juice from different fermentation times and scales.

The mature coconut water (MCW) is rich in nutrients, but its sour and astringent taste makes it unsuitable for direct consumption. In this study, a co-fermentation system employing Saccharomyces cerevisiae and Lactiplantibacillus plantarum was developed to enhance the flavor of MCW, wherein an indigenous S. cerevisiae 1-7-1 was screened for optimal sensory characteristics when co-fermented with L. plantarum A33. Co-fermentation changed odor and taste characteristics of MCW with a broad range of organic compounds and the high richness taste attribute. Compared to fermentation with L. plantarum A33, co-fermentation increased total volatiles content from 81,487 μg/L to 996,944 μg/L, with characteristic aroma-active compounds identified as ethyl caprylate (91,032 μg/L), ethyl caprate (35,160 μg/L), isoamyl alcohol (136,376 μg/L), octanoic acid (267,673 μg/L), and isoamyl acetate (25,336 μg/L). The amino acid metabolic pathway was the most significantly perturbed pathway during co-fermentation. This study provides an innovative strategy for developing value-added MCW-based beverages.

The dynamic changes in phenolic composition and antioxidant activity, and the potential effect on foam cell formation and cholesterol efflux during noni (Morinda citrifolia Linn.) fruit juice fermentation were investigated in this study. The composition of phenolic compounds was significantly different at various fermentation times. Rutin, quercetin, and isoquercitrin were the major phenolics in fermented noni fruit juice based on a quantitative analysis of representative phenolics. The contents of caffeic acid, 2,4-dihydroxybenzoic acid, p-coumaric acid, rutin, and quercetin tended to increase, while those of isoquercitrin decreased during the fermentation process. Fermented noni juice extracts showed high antioxidant activities against 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), hydroxyl radical scavenging activity, and ferric reducing antioxidant power. Notably, the highest antioxidant activity was observed after 28 days of fermentation. Furthermore, the treatment of fermented noni juice extracts was shown to reduce foam cell formation, intracellular cholesterol level, and the cholesterol esterification ratio. A correlation analysis indicated a strong positive relationship between the phenolic composition, antioxidant activity, and the ratio of cholesterol ester and total cholesterol. This study may provide a theoretical basis for the quality improvement and standardized production of fermented noni fruit juice, thus promoting the development of the noni food industry.

The potential of lactic acid bacteria (LAB) to enhance fruit juice is well known; however, the optimal fermentation strategy for wampee juice (WJ), considering its physicochemical and sensory characteristics and antioxidant activity, remains to be explored. For WJ fermentation, a co-culture of three LAB strains—Pediococcus pentosaceus SL05, Pediococcus acidilactici SL08, and Lactiplantibacillus plantarum JYLP-002—was optimized using a combined approach of simple lattice mixture design and a genetic algorithm (GA). After 48 h of fermentation, the optimal mixed fermentation group demonstrated a comprehensive superiority over both the unfermented and single-strain fermentation groups. It exhibited significantly higher levels of viable bacterial counts, total organic acid content, total phenolic and flavonoid contents, antioxidant capacity, and an enriched profile of volatile flavor compounds. Moreover, comprehensive volatile profiling via HS-SPME-GC-MS and HS-GC-IMS identified 59 and 29 volatile components, respectively; β-phellandrene, α-terpineol, α-pinene, methyl acetate, (E)-3-hexen-1-ol, and 3-methyl-1-butanol, as well as butanal, (E)-3-hexenoic acid, β-pinene, and propyl butanoate, were considered as key aroma contributors in the fermented WJ (FWJ). This study provides a theoretical foundation and practical framework for the enhancement of WJ quality through mixed LAB fermentation.

Rambutan shell, a major agro-industrial by-product, is a promising source of bioactive polyphenols. This study aimed to optimize polyphenol extraction from the rambutan shell of Baoyan NO.7 (BY-7) using deep eutectic solvent (DES) and to purify the extract with AB-8 resin. The adsorption mechanism was elucidated, and the polyphenol profile was characterized via next-generation metabolomics (NGM). The optimized extract showed high total phenolic (178.89 mg GAE/g), flavonoid (152.93 mg RE/g), and proanthocyanidin (41.89 mg CE/g) contents, along with potent antioxidant (DPPH: 7061.49, FRAP: 6925.34 μmol TE/g) and anti-glycemic activities (α-amylase IC₅₀: 2.62 mg/mL; α-glucosidase IC₅₀: 70.78 μg/mL). Adsorption followed Langmuir and pseudo-second-order kinetic models, indicating a spontaneous process. To the best of our knowledge, proanthocyanidin B1 was identified in the rambutan shell of BY-7 for the first time. Significant correlations were found between 11 polyphenols and the bioactivities. This work provides a theoretical foundation for valorizing rambutan shell resources.