Valorization of agri-food waste through the extraction of bioactive molecules. Prediction of their sunscreen action.

The aim of this work was to identify the phenolic composition of 18 different vegetable residues and to determine the relationship between their phenolic compounds, antioxidant capacity and sun protection factor. For this purpose, samples of agri-food residues were analyzed to quantify their antioxidant capacity, total polyphenol and flavonoid content, sun protection factor and individual phenolic compounds through HPLC-DAD-FLD. Among the different phenolic compounds found in the extracts, the phenolic acids, especially caffeic acid, chlorogenic acid, p-coumaric acid and protocatechuic acid were the ones that have been most frequently identified, and, therefore, are present in a wide range of extracts. Black chai tea, lemon ginger tea and peanut extracts were the most antioxidant and photoprotective extracts. Phenolic compounds in the extracts have been found to contribute to their antioxidant activity and are closely correlated to their photoprotective capacity. A regression model that allows predicting the photoprotective capacity of any extract based on its total phenol content has been developed as a tool to determine the most suitable industrial application for each vegetable extract.

Reducing SO2 Doses in Red Wines by Using Grape Stem Extracts as Antioxidants.

SO2 is a very important wine preservative. However, there are several drawbacks associated with the use of SO2 in wine. The aim of this work is to evaluate the effect of the partial substitution of SO2 in the Tempranillo wine by a Mazuelo grape stem extract and by a commercial vine wood extract (Vinetan®). The results were compared with a control sample (with no addition of any extract). After 12 months of storage in a bottle, total anthocyanin content, together with total polyphenol and flavonoid content were slightly higher for control wines than for those treated with extracts. These differences were of little relevance, as no differences in antioxidant activity were found between any of the wines at the end of the study. The sensory analysis revealed that the use of both extracts as partial substitutes of SO2 could lead to wines with good organoleptic properties, similar or even better to the control ones.

Oak wood extracts applied to the grapevine. An alternative to obtain quality Garnacha wines.

Stomata in leaves regulate gas interchange and transpiration in the grapevine and through these pores both the penetration of aqueous solutions with nutrients as well as the excretion of products take place. The aim of this work was to study the influence of spraying the vineyard with toasted and untoasted oak extracts on the volatile composition and on the organoleptic quality of wine made from Garnacha grapes. The results were compared with a Garnacha control wine obtained with grapes sprayed with distilled water. The absorption of the compounds from the oak wood extracts was irregular and some of these compounds were modified by the yeast during fermentation so as to prevent fermentation problems. This was observed particularly in the case of furfural which were transformed into furfuryl alcohol by yeast in order to avoid irreversible cellular damage. On applying a discriminant analysis to the concentration of volatile compounds in the wines, the three treatments (control, toasted and untoasted oak extracts) were differentiate. The wine obtained from grapes treated with toasted oak extract showed a more intense wood aroma after 18months of bottle aging than the other wines. Likewise, spicy aromas were found to be more intense in the samples treated with some type of oak wood extracts.