Impact of storage on the functional characteristics of a fermented cereal product with probiotic potential, containing fruits and phytosterols.

The aim of this work was to study the changes in the functional characteristics of a fermented maize product containing fruits, and enriched with phytosterols. Functional characteristics (natural antioxidants and phytosterols content, in vitro antioxidant capacity and probiotic viability), lipid oxidation, and physicochemical parameters were investigated during 4 weeks of storage at 4 °C. The differences between one formulation elaborated with semi-skimmed powdered milk (Basic Product) and another with whey protein isolate (WPI Product) were evaluated. The content of polyphenols, carotenoids and tocopherols remained unchanged during the storage of both formulations. These compounds increased the antioxidant capacity in both products compared to the control formulation (without fruits), which was displayed along the whole storage period. The doses of phytosterols and the probiotic potential were maintained to the end of the storage period for both formulations. Basic and WPI products represent novel foods with desirable functional characteristics preserved during commercial storage.

Proteomic analysis of Saccharomyces cerevisiae to study the effects of red wine polyphenols on oxidative stress.

Understanding the molecular mechanisms underlying the "French paradox" has contributed to a growing interest in the investigation of the biological activity of red wine polyphenols (RWP). The main goal of this research is to provide valuable information on how RWP could exert their biological action at the cellular level. So, we report a proteomic analysis of S. cerevisiae exposed to both pro-oxidant (H2O2) and antioxidant (wine) agents. Cellular proteome analysis shows that RWP modify the level of certain proteins. Under both normal conditions (Wine treatment) and oxidative stress situations (Wine + H2O2 treatment), the proteins involved in the metabolism and biosynthesis of biomolecules were down-regulated, while one ribosomal protein was up-regulated, probably performing its ribosome-independent functions, and so contributing to the stress defense system. Considering this action mechanism, we suggest that RWP may be acting as mild pro-oxidants and, therefore, exerting a hormetic effect that leads to the strengthening of cells' antioxidant capacity.

Bioaccessibility of polyphenols and antioxidant properties of the white grape by simulated digestion and Caco-2 cell assays: Comparative study with its winemaking product.

The primary objective of this study was to assess the changes on phenolic composition and AC (antioxidant capacity) of white grape and its winemaking product, during in vitro gastrointestinal (GI) digestion. Phenolic compounds were evaluated by HPLC-MS/MS. The AC was measured by in vitro (FRAP, ABTS and DPPH) and cellular (Caco-2 cells) assays. Digestion had a reducing effect on phenolic content, being only 31% and 67% of native polyphenols from grapes and wines, respectively, potentially bioaccessible. At same polyphenol concentration, cellular AC of nondigested and digested foods was the same, indicating that changes in phenolic profile did not modify the bioactivity. Phenolic acids, in addition to quercetin, were the most resistant polyphenols to digestion, and would be the most relevant to explain the biological activity of digested foods. Results indicate that the changes occurred in the native phenolic profile of foods as a consequence of GI digestion, do not modify the bioactivity of white grapes and wines.

From grape to wine: Changes in phenolic composition and its influence on antioxidant activity.

The evolution of phenolic compounds and their relationship with the antioxidant capacity (AC) of samples taken along the winemaking process of three Vitis vinifera L. cv., Syrah, Merlot and Cabernet Sauvignon grown in Argentina were studied. Forty-five compounds were identified by HPLC-PDA-MS/MS, while the AC was determined by FRAP, ABTS and DPPH assays. Results show that phenolic composition and AC vary along the winemaking process and between varieties. Multiple regression analysis showed a high correlation between phenolic composition and AC of samples, being anthocyanins the main family with significant contribution to AC. In addition, quantitative differences in specific phenolic compounds help to explain differences in AC observed between varieties. A high phenolic content and bioactivity still remain in pomaces which support its use as an inexpensive source of antioxidants.