Effect of thermal processing on the phenolic profiles, antioxidant capacity, and volatile compounds of fig wines

Dynamic changes and correlation of quality, flavor and microorganisms of Mei (Prunus mume) vinegar during fermentation and clarification

Mei (Prunus mume) is a highly nutritious fruit whose value is often underutilized due to its perishable nature and challenges in post-maturation storage. This study evaluated the changes and correlations among quality, volatile flavor compounds (VFCs), and microorganisms in Mei vinegar (MV) during acetic acid fermentation (AAF) and low temperature clarification (LTC) using various clarifiers. The results indicated that AAF enhanced the bioactive components and antioxidant capacity of MV. A total of 73 VFCs were identified, comprising 9 alcohols, 28 esters, 5 aldehydes, 18 acids, 4 phenols, 1 ketone, 5 alkanes, and 3 others. Among these, the number and relative content of esters and acids exhibited dominance both in AAF and LTC. Firmicutes and Pediococcus were predominant at the phylum and genus levels, respectively. After 1 d of AAF, the relative abundances of Firmicutes and Pediococcus increased significantly, while LTC reduced their abundance. Among the 20 stable VFCs in MV, most esters and alcohols showed positive correlations with the top 10 bacteria at the phylum and genus levels, while certain acids were negatively correlated with these bacteria. Therefore, these findings offer valuable insights for the development of MV, the selection of clarifiers, and offer a theoretical basis for improving MV quality and flavor.

Evaluation of fig-milk dessert bioactive properties as a potential functional food

The fig-milk dessert, a traditional and nutritionally rich treat infused with bioactive compounds, was subjected to a comprehensive analysis in this study. The novelty of this research lies in the investigation of the in vitro antioxidant, anticancer, and antimicrobial potential of the fig-milk dessert. This was accomplished through the utilization of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, Annexin/propidium iodide staining, microtiter plate-based assay and agar well diffusion, respectively, for the first time. Additionally, the study assessed the total phenols and flavonoid content of the extract using the Folin-Ciocalteu assay and the aluminum chloride method, respectively. The findings revealed that the cooking method exerted a significant influence on the bioactive properties and nutritional composition of the dessert. Among the samples analyzed, CM1, consisting of figs steamed for 2 min and milk heated to 70°C, exhibited remarkable characteristics. This sample demonstrated the highest peptide concentration (1290 mg/L), superior antioxidant and anticancer activities, and favorable sensory attributes. Specifically, CM1 induced apoptosis in 84% of AGS cells and inhibited 68% of free radicals in the DPPH assay. It is noteworthy that the fig-milk dessert did not exhibit any antibacterial properties. These discerning results carry substantial implications for the development of functional dairy products endowed with both nutritional and potential therapeutic properties.

Effect of thermal treatments on volatile profiles and fatty acid composition in sweet corn (Zea mays L.)

This study analyzed the effects of thermal processing on volatiles and fatty acids in sweet corn. There were 27 volatiles measured in fresh samples, and 33, 21, and 19 volatiles identified in the steaming, blanching, and roasting groups, respectively. Relative odor activity values (ROAVs) showed that characteristic aroma-active volatiles of sweet corn after thermal treatments included: (E)-2-nonenal, 1-octen-3-ol, beta-myrcene, dimethyl trisulfide, 1-(4,5-dihydro-2-thiazolyl)-ethanone, and d-limonene. Thermal treatments significantly increased the unsaturated fatty acids (oleic acid and linolenic acid) of sweet corn by 110 to 183% compared to fresh samples. Meanwhile, many characteristic volatiles were found that derived from the oxidative cleavage of fatty acids. The sweet corn aroma obtained by steaming for 5 min was considered the closest to fresh corn. Our research provided insight into aroma composition of different thermally processed sweet corn and laid the foundation for further exploring the sources of aroma compounds in thermally processed sweet corn.

A comparative study of the effect of bacteria and yeasts communities on inoculated and spontaneously fermented apple cider

Understanding bacteria and yeasts communities can reduce unpredictable changes of apple cider. In this study, apple juice inoculated with Saccharomyces cerevisiae WET 136 and fermented spontaneously were compared, the relationships of bacteria, yeasts, organic acids, and volatiles were analyzed. Results showed that microbial diversity affected the fermentation, organic acids and volatiles in apple ciders. In the first four spontaneous fermentation days, LAB (lactic acid bacteria) multiplied and reached 7.89 lg CFU/mL, and then triggered malolactic fermentation (MLF), leading to malic acid decreased by 3880.52 mg/L and lactic acid increased by 4787.55 mg/L. The citric, succinic and fumaric acids content was 2171.14, 701.51 and 8.06 mg/L lower than that in inoculated cider, respectively. Although the yeasts multiplied during spontaneous fermentation, it did not reach 7.50 lg CFU/mL until the 5th day, which led to a long lag period, as well as later and lower production of acetaldehyde and higher alcohols. The inoculated yeast inhibited LAB, acetic acid bacteria, Rahnella, and non-Saccharomyces. Yeasts were the key to produce citric acid, acetaldehyde and 3-methyl-1-butanol in apple cider; while bacteria were closely related to the formation of lactic acid, acetic acid and ethyl acetate. It suggested that low higher alcohols and acetaldehyde can be realized by selecting yeasts, and Leuconostoc pseudomesenteroides can work as candidate to reduce L-malic and citric acids in apple cider.