Organosolv Treatment of Red Grape Pomace for Effective Recovery of Antioxidant Polyphenols and Pigments Using a Ternary Glycerol/Ethanol/Water System under Mild Acidic Conditions.

The purpose of this investigation was (i) the development of a novel, green tertiary solvent system, composed of water, ethanol and glycerol, and (ii) the implementation of an organosolv treatment of red grape pomace (RGP) for the efficient production of polyphenol-containing extracts with enhanced antioxidant properties. The treatment developed was performed under mild acidic conditions, imparted by the addition of citric acid, and it was first evaluated on the basis of severity, establishing linear models that described the correlation between treatment performance and combined severity factors. To solicit treatment optimization, response surface methodology was implemented, considering solvent acidity and residence time as the treatment variables. The optimized treatment afforded maximum total polyphenol (166 ± 6 mg GAE g-1 DM), total pigment (4.4 ± 0.2 mg MvE g-1 DM) and total flavanol (31.5 mg CtE g-1 DM) yields and extracts with particularly enhanced antioxidant activity. This might be attributed to specific constituents with high antioxidant potency, such as catechin, determined in the extract using high-performance liquid chromatography. Thus, the treatment developed is proposed as a highly efficient process to generate RGP extracts enriched in polyphenolic compounds, with enhanced antioxidant activity. Such extracts might then be valorized as food additives, to provide antioxidant protection and/or pigmentation.

Natural Pigments of Anthocyanin and Betalain for Coloring Soy-Based Yogurt Alternative.

The aim of this work was to evaluate the color stability of betalain- and anthocyanin-rich extracts in yogurt-like fermented soy, in order to develop a preliminary understanding of how these pigments behave in this type of food system during storage for 21 days at 4 °C. Thus, the extracts of red beetroot, opuntia, hibiscus and red radish were integrated into the yogurt-like fermented soy in two different ways-directly after lyophilization, and encapsulated in nanosystems based in soybean lecithin-as this approach has never been used to further increase the value and potential of the dairy-free alternatives of yogurt-like fermented soy. The results showed that non-encapsulated betalain-rich extracts from red radish are the most promising for coloring yogurt-like fermented soy. However, encapsulated opuntia extracts can also be an alternative to supplement the soy fermented beverages with betalains, without changing significantly the color of the system but giving all its health benefits, due to the protection of the pigments by nanoencapsulation.

Value-Added Lager Beer Enriched with Eggplant (Solanum melongena L.) Peel Extract.

Manufacturing beer with a high biological value requires identifying new methods for increasing the health-enhancing compounds level. The aim of this study was to increase the biological value of beer by adding antioxidant-rich eggplant (Solanum melongena L.) peel extract (EPE). The total phenolic content (TPC), total flavonoid content (TFC), and total monomeric anthocyanin content (TMA) were determined. Moreover, the antioxidant activity was evaluated by different radical scavenging assays. The addition of different levels of EPE resulted in a significant increase of TPC and TFC of beer samples from 0.426 to 0.631 mg GAE/mL, and from 0.065 to 0.171 mg CE/mL, respectively. The EPE-supplemented beer samples developed a reddish color because of the presence of anthocyanin pigments. The TMA content of beer varied from 0.011 to 0.083 mg D3G/mL with the level of added EPE. The HPLC analysis indicated that the anthocyanins prevailing in the eggplant peels were delphinidin-3-rutinoside, delphininidin-3-glucoside and delphinidin-3-rutinoside-5-glucoside. The radical scavenging assays indicated a linear increase of the antioxidant activity following EPE addition, without altering the physicochemical parameters of the beer. These results are promising for using the EPE as a functional ingredient for beer production.