Effect of Drying Methods on Bioactive Compounds and Antioxidant Capacity in Grape Skin Residues from the New Hybrid Variety "BRS Magna".

The effects of the drying process using the conventional oven and freeze-drying on the thermogravimetric profile, proximate composition, color parameters, individual bioactive compounds, and antioxidant activity in the grape residue (skin) were evaluated. Twenty individual phenolic compounds were identified, where a variation in concentration was observed for flavonols, stilbenes, phenolic acids, flavonoids, procyanidins, and particularly anthocyanins (malvidin-3,5-di-O-glucoside of 253.2-536.9 mg/kg) due to the drying process. Drying in a conventional oven caused a decrease of 23% of the total polyphenols. The skin of the BRS magna grape has a high concentration of total phenolic content of 489.5-148.3 mg.GAE/100 g, total anthocyanin content of 124.9-260.1 mg.CE/100 g, and total flavonoid content of 12.7-26.0 mg.QE/100 g. The results of free radical scavenging activity (1.26-4.91 µg/mL, as EC50) and ferric reducing antioxidant power (82.93-184.10 µmol/g of skin as equivalent to Fe2SO4) indicate high antioxidant activity, independently of the drying process applied. It was concluded that, if the application is directed to anthocyanin compounds, the use of lyophilization is recommended. On the other hand, if the interest is in bioactive compounds that exert antioxidant activity, conventional oven-drying can be used.

Biological activities of a mixture of biosurfactant from Bacillus subtilis and alkaline lipase from Fusarium oxysporum

In this study, we investigate the antimicrobial effects of a mixture of a biosurfactant from Bacillus subtilis and an alkaline lipase from Fusarium oxysporum (AL/BS mix) on several types of microorganisms, as well as their abilities to remove Listeria innocua ATCC 33093 biofilm from stainless steel coupons. The AL/BS mix had a surface tension of around 30 mN.m-1, indicating that the presence of alkaline lipase did not interfere in the surface activity properties of the tensoactive component. The antimicrobial activity of the AL/BS mix was determined by minimum inhibitory concentration (MIC) micro-assays. Among all the tested organisms, the presence of the mixture only affected the growth of B. subtilis CCT 2576, B. cereus ATCC 10876 and L. innocua. The most sensitive microorganism was B. cereus (MIC 0.013 mg.mL-1). In addition, the effect of the sanitizer against L. innocua attached to stainless steel coupons was determined by plate count after vortexing. The results showed that the presence of the AL/BS mix improved the removal of adhered cells relative to treatment done without the sanitizer, reducing the count of viable cells by 1.72 log CFU.cm-2. However, there was no significant difference between the sanitizers tested and an SDS detergent standard (p<0.05).