Wenxue Zhang

This study investigated the metabolic characteristics of mulberry wine produced by co-fermentation with Saccharomyces cerevisiae (SC) and two different Pichia kluyveri (PK). Although S. cerevisiae inhibited the growth of P. kluyveri during co-fermentation, P. kluyveri showed robust growth adaptability. Classical oenological parameters were not significantly altered by co-fermentation compared to pure-fermentation. The P. kluyveri significantly modulated amino acid metabolism pathways during co-fermentation, enhancing the biosynthesis of higher alcohol acetate compounds. Furthermore, co-fermentation strategy promoted the production of volatile flavor compounds, particularly esters and alcohols, which enriched the wine with distinct floral and fruity flavors. This study provides novel insights into the metabolic mechanisms of co-fermentation with SC and PK strains and highlights the potential of P. kluyveri as a co-fermentation agent for improving the aromatic complexity of fruit wines.

Dazhu glutinous rice wine is a well-known traditional Chinese rice wine, and many local factories and handicraft workshops use different fermentation methods to produce it. Still, the influence of fermentation processes on glutinous rice wine is unclear. This study aimed to compare the difference between the two fermentation methods in the quality and bacterial composition of Dazhu glutinous rice wine. Results showed that the alcoholic content (P < 0.0001) and acidity (P < 0.01) in the rice wine fermented after packaging (PFRW) were higher than in the rice wine packaged after fermentation (FPRW), but the total sugar content was lower. Most amino, such as glutamic acid proline, and lactic acid were significantly higher in FPRW (P < 0.0001). In addition, the aroma, flavor and taste were better in FPRW than in PFRW. The Limosilactobacillus fermentum, Pediococcus pentosaceus, and Lactococcus lactis were dominant bacteria in FPRW, positively associated with amino acid and lactic acid. At the same time, Alcaligenaceae and Pedobacter nutriment were dominant bacteria in PFRW and negatively correlated with the quality. These implied that lactic acid bacteria significantly contributed to accumulating flavor ingredients and improving the quality of Dazhu glutinous rice wine. This study provides reference data for improving the quality of rice wine.

Guaiacol, 4-vinylguaiacol, 4-methylguaiacol and 4-ethylguaiacol, being guaiacol compounds characterized by spicy and smoky flavor, are important functional factors and key aroma components in sesame flavore Baijiu. In this study, to enhance the content of guaiacol compounds in this product, a strain of Pseudomonas azotoformans YF-58 which produced guaiacol compounds was added to the Zaopei (fermented grains) in the form of bacterial Fuqu. Subsequently, the effect of YF-58 strain on the fermentation system was explored from multiple perspectives, including microbial community composition, volatile flavor substance content and the expression levels of functional enzymes. The results showed that the addition of YF-58 strain altered the relative abundance of microorganisms such as Lactobacillus, Aspergillus, Pseudomonas, Staphylococcus, Weiniella, Bacillus and Corynebacterium in Zaopei. Moreover, the contents of acids, esters, alcohols and guaiacol compounds in Zaopei increased. Additionally, key enzymes associated with guaiacol compounds formation, such as 4-hydroxy-3-polyprenylbenzoate decarboxylase (EC 4.1.1.98), cellulase (EC 3.2.1.4) and catechol O-methyltransferase (EC2.1.1.6), were up-regulated. As a result, the contents of guaiacol, 4-methyl guaiacol, 4-ethylguaiacol and 4-vinylguaiacol in sesame flavor Baijiu were significantly increased by 193.1, 11.6, 95.4 and 105.2%, respectively. The research findings provided some theoretical guidance for enhancing the content of volatile flavor substances in Baijiu.

High-value resources beyond oil extraction for the olive industry need to be developed due to increased olive production. Soluble dietary fibers (SDFs) and olive proteins (OPIs) are important components of olives. However, the commercial production process partially damages OPIs’ emulsifying and foaming properties. Thus, the preparation of SDF-OPI complexes would help protect and even improve the emulsifying and foaming properties. The effects of pH and thermal–ultrasonic treatment on the complexation were explored, which showed that the SDF-OPI complexes prepared at pH 5 exhibited superior solubility (p < 0.05). SDF addition noticeably improved OPI thermal stability, emulsifying properties, and foaming properties. Moreover, the complexes prepared by thermal–ultrasonic treatment exhibited higher emulsion stability and lower emulsification activity than those prepared without thermal–ultrasonic treatment. In the acidic system, the electrostatic interaction was considered the main driving factor, assisted by the hydrophobic interaction. Additionally, after thermal–ultrasonic treatment, the covalent binding was observed by infrared spectroscopy. These results revealed the interaction mechanism between SDF and OPI, and the complexes significantly enhanced the functional properties of OPI. This study provides a reference for the high-value utilization of olives, thus broadening their potential uses in the food sector and beyond.