The uncontrolled natural pre-fermentation process of coconut water represents great hidden safety hazards, unstable production, and impact on the quality of nata de coco–the trade name of bacterial cellulose (BC) in food industry. In this study, BC production from Komagataeibacter nataicola Q2 was conducted in the media of coconut water (50%, v/v) pre-fermented by 11 coconut-sourced yeast strains in static. Results suggested that coconut water pre-fermented by different yeast strains had varied effects on the production of BC. Compared with the use of fresh coconut water, the use of coconut water pre-fermented by Saccharomyces cerevisiae SC7 increased the BC yield by 165%. Both natural pre-fermentation and SC7 pre-fermentation altered the concentrations of amino acids in fresh coconut water. The addition of selected amino acids aspartic acid, glutamic acid, serine, methionine, threonine, isoleucine, phenylalanine, and proline at different concentrations had varied effects on the production of BC. The yield of BC was the highest when adding 3.0% (w/v) methionine. Moreover, adding 3.0% methionine allowed the production of BC with larger loops of looser aggregated microfibers, increased the crystallinity of BC from 64.8% to 69.4%, but decreased the temperature of maximum weight loss rate, hardness, and adhesiveness from 223 °C, 8.68 kg, and 92.8 g.sec to 212 °C, 7.01 kg, and 58.5 g.sec, respectively, in the test condition.

The aim of this work was to compare the composition and physicochemical properties (SEM, XRD, solubility, swelling power, paste clarity, retrogradation, freeze–thaw stability, thermal property, and pasting property) of three Chinese yam (Dioscorea opposita Thunb.) starches (CYYS-1, CYYS-2, and CYYS-3) in Yunlong town, Haikou, Hainan Province, China. Our results show that all the CYYS gave a typical C-type X-ray diffraction pattern. The swelling power of CYYS varied from 10.79% to 30.34%, whereas solubility index was in the range of 7.84–4.55%. The freeze–thaw stability of each CYYS showed a contrary tendency with its amylose content. In addition, CYYS-3 showed the highest T_o (81.1 °C), T_p (84.8 °C), T_c (91.2 °C), and ΔH (14.1 J/g). The pasting temperature of CYYS-1 increased significantly with sucrose addition. NaCl could inhibit the swelling power of CYYS. There were significant decreases in pasting temperature and pasting time of CYYS when pH decreased.

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.

In this work, the hydrothermal extract of spent coffee grounds (SCG) was used to make alcoholic beverages with commercial S. cerevisiae strain D254. The sensory characteristics of the SCG alcoholic beverages were analyzed using sensory description, electronic nose, electronic tongue, and gas chromatography-mass spectrometry (GC-MS). The results suggested that the supplement of 0.20% (NH₄)₂HPO₄ was effective at improving growth and alcohol fermentation of Saccharomyces cerevisiae D254 in SCG extract. SCG fermented beverages (SFB) and SCG distilled spirits (SDS) produced at the optimized fermentation conditions had appropriate physicochemical properties and different sensory characteristics. Fermentation aromas, especially esters, were produced in SFB, increasing the complexity of aroma and lowing the irritating aroma. The combination of original and fermentation components might balance the outstanding sourness, astringency, and saltiness tastes of SFB. The fermentation aroma was partially lost and the sourness, bitterness, astringency, and saltiness tastes were relieved in distillation, leading to the relatively more prominent aroma typicality of coffee and a soft taste. These findings lay a foundation for producing new high-quality coffee-flavored alcoholic beverages or flavoring liquors.