Influence ofOenococcus oeniandBrettanomyces bruxellensison Aged Wine Microbial Taxonomic and Functional Profiles

In the wine making process, the interactions between lactic acid bacteria (LAB), yeast and other wine microflora have an impact on the wine quality. In this study, we investigate the influence of the LABOenococcus oeniand the spoilage yeastBrettanomyces bruxellensison the microbial community of a Cabernet Sauvignon wine. We generated metagenomic datasets from inoculations of three strains ofB. bruxellensis, in combination with twoO. oenistrains, one with and one without cinnamoyl esterase activity. This esterase activity releases hydroxycinnamic acids (HCAs) that can subsequently be processed by someB. bruxellensisstrains able to generate off-flavor compounds. We evaluated the influence of theO. oeniandB. bruxellensison the microbial taxonomic and functional potential profile, particularly regarding off-flavor formation due to HCAs. We found that the effect on the microbial profiles depends oni) theO. oeniandB. bruxellensisstrains being combined andii) the abundance they reach in the final wine, which depends on certain unidentified conditions. We confirmed that the potential ofB. bruxellensisto produce off-flavor compounds from HCAs depends on the strain. Interestingly, the samples without microbial inoculants also had this potential, suggesting that native grape microbiota could also influence the levels of HCA. We also found that the presence ofB. bruxellensisdoes not interfere with the malolactic fermentation of the evaluatedO. oenistrains, which leads to a less acidic taste. We show that metagenomic approaches can help uncover the complex wine microbial community traits, such as flavor, impacted by the simultaneous presence ofO. oeniandB. bruxellensis.

Biotransformation Strategy To Reduce Allergens in Propolis

ABSTRACTPropolis (bee glue) is a resinous, sticky, dark-colored material produced by honeybees. Propolis today, due to its medicinal properties, is increasingly popular and is extensively used in food, beverages, and cosmetic products. Besides its numerous positive properties, propolis may also have adverse effects, such as, principally, allergic eczematous contact dermatitis in apiarists and in consumers with an allergic predisposition. In this study, we found appropriate conditions for removing caffeate esters, which are the main allergenic components, from raw propolis. The proposed method consists of the resuspension of propolis in a food grade solvent, followed by a biotransformation based on the cinnamoyl esterase activity ofLactobacillus helveticus. We showed that the reduction of caffeate esters byL. helveticusdid not affect the content of flavonoids, which are the main bioactive molecules of propolis. Furthermore, we verified that the biotransformation of propolis did not cause a loss of antimicrobial activity. Finally, we demonstrated that the ability ofL. helveticusto hydrolyze caffeate esters in propolis is strain specific. In conclusion, the proposed strategy is simple, employs food grade materials, and is effective in selectively removing allergenic molecules without affecting the bioactive fraction of propolis. This is the first study demonstrating that the allergenic caffeate esters of propolis can be eliminated by means of a bacterial biotransformation procedure.