Impact of wine technology on the variability of resveratrol and piceids in Saperavi ( Vitis vinifera L.)

Different approaches to enhance resveratrol content in wine

Resveratrol is a polyphenol with antioxidant properties and possible beneficial effects on human health. Grapes, peanuts, berries, cacao beans and red wine contain resveratrol. Resveratrol attracts attention due to its bioactive properties, however, the concentration of this compound is not high in grape and wine. Therefore, different studies have been carried out to increase resveratrol level in these products. Several factors such as the grapevine variety, the climatic conditions and the viticultural practices used to create stress on the vine affect the level of resveratrol. Winemaking technologies applied during pre-fermentation, fermentation and post–fermentation stages could also have an effect on the concentration of this stilbene. In addition, recent studies have evaluated biotechnological approaches through the use of different bacteria and yeast strains to produce wine with increased resveratrol content. In this review, the most important factors contributing to increase the resveratrol concentration in grapes and wines are examined. Besides, analytical methods to determine resveratrol content in wine are addressed.

Fermentation transforms the phenolic profiles and bioactivities of plant-based foods

Phenolics are a group of compounds derived from plants that have displayed potent biological activities and health-promoting effects. Fermentation is one of the most conventional but still prevalent bioprocessing methods in the food industry, with the potential to increase phenolic content and enhance its nutritive value. This review details the biotransformation of different classes of phenolics (hydroxycinnamic and hydroxybenzoic acids, flavonoids, tannins, stilbenoids, lignans, alkylresorcinols) by various microorganisms (lactic acid bacteria, yeast, filamentous fungi) throughout the fermentation process in plant-based foods. Several researchers have commenced the use of metabolic engineering, as in recombinant Saccharomyces cerevisiae yeast and Escherichia coli, to enhance the production of this transformation. The impact of phenolics on the metabolism of microorganisms and fermentation process, although complex, is reviewed for the first time. Moreover, this paper highlights the general effect of fermentation on the food's phenolic content, and its bioaccessibility, bioavailability and bioactivities including antioxidant capacity, anti-cancer, anti-diabetic, anti-inflammation, anti-obesity properties. Phenolics of different classes are converted into compounds that are often more bioactive than the parent compounds, and fermentation generally leads to a higher phenolic content and antioxidant activity in most studies. However, biotransformation of several phenolic classes is less studied due to its low concentration and apparent insignificance to the food system. Therefore, there is potential for application of metabolic engineering to further enhance the content of different phenolic classes and bioactivities in food.

Preparation and in vitro performance evaluation of resveratrol for oral self-microemulsion

The purpose of this study was to improve the solubility of resveratrol (Res) by a self-microemulsifying drug-delivery system (SMEDDS). Through a solubility experiment, the pseudoternary phase diagram and ternary phase diagram were used to optimize the Res SMEDDS formula. The optimum formulation consisted of 5% IPM, 20% PEG400, and 65% Cremophor RH40. The water solubility, stability, in vitro release and antioxidant activity of the Res SMEDDS were characterized. The Res solubility in the SMEDDS was at least 1,000 times compared to that in water. The average droplet size of the microemulsion was 28.00±1.67 nm and uniform distribution. The Res SMEDDS should be stored at low temperature and in the dark to avoid light conditions. Res SMEDDS was able to improve the in vitro release rate of Res, and the in vitro release of Res from Res SMEDDS was significantly faster that of Res powder and unaffected by pH value of media. Antioxidant assays showed that antioxidant activities of Res in Res SMEDDS were unaffected compared to Res powder. Cytotoxicity study indicated that Res SMEDDS at the concentration of less than 100 μM was safe. These results demonstrated the potential use of Res SMEDDS for oral administration of Res.