Polyphenol extraction from grape wastes: Solvent and pH effect

World wine industry transforms 10% - 25% of raw grapes into residues, mainly represented by lees, grape marcs, seeds and stems. These by-products are a rich source of polyphenols and therefore they can be used to produce new added value products. The aim of this work wasto determine the best process conditions(treatment time, % of ethanol and pH of the solvent)during solid-liquid extraction of polyphenolsfrom grape marcs, by analyzing the phenolic content of the extracts, namely: total polyphenol content, flavanols, flavonols, phenolic acids and anthocyanins. Antioxidant activity of the extracts was also determined. An extraction time of two hours was enough since longer times did not increase process yields. Best extraction yields were obtained for 75% ethanol solutions. Basic pH led to better yields in extracting media with low percentage of ethanol, whereas acid pH presented better extraction yields in extracting media with high percentage of ethanol. Among all the polyphenols extracted, anthocyanins were themost abundant representing over 40% of the total. In general, the best process conditions were 2 h ofextraction in a 75% EtOH liquid mixture at pH =2.

Water sorption isotherms of globe artichoke leaves

One third of the artichoke production is used in industrial processes, where up to 70% - 85% of the initial raw material is transformed into solid wastes. For an adequate management of these wastes, it is necessary to know their water sorption properties, because physical, chemical andbiological changes which occur during theirstorage depend on water-solid interactions. The objectives of this work are to experimentally determine equilibrium sorption (adsorption anddesorption) data of artichoke wastes at different temperatures (25°C - 55°C), as well as correlate and predict water sorption isotherms using bibliographic models. Equilibrium moisture content ranged 0 - 0.6 kg water/kg dry solid (water activity 0.05 - 0.9). Water sorption isotherms were classified between Types II and III. Hysteresis phenomenon was not observed, neither was the dependence of the equilibrium data with temperature. BET, GAB, Oswin and Peleg correlation models were satisfactorily fitted to experimental data. A predictive model based on composition and physical state of artichoke waste components was also successfully used to reproduce experimental data.

Impact of common gastrointestinal disorders in elderly on in vitro meat protein digestibility and related properties

This study aimed to in vitro evaluate the impact of common gastrointestinal(GI)alterations appearing with aging on protein digestibility,and functional related properties,in four different meats(chicken,turkey,pork and beef).Thus,three elderly digestion models were stated as long as altered GI conditions affected at oral(E1),oral and gastric(E2)and oral,gastric and intestinal stages(E3).Healthy adult GI conditions were also mimicked as standard control model(C).A notable trichloroacetic acid(TCA)soluble protein and the free amino acids(FAA)release reduction(p<0.05)were found under intestinal suboptimal conditions(E3),being more accused in beef than in other meats.Thus,chicken intake would be more advisable,than other meats,in terms of protein digestibility;while beef would provide a greater net supply of FAA under E3 model conditions.Gastric altered conditions,seem to favor protein solubility.Finally,while gastric and intestinal suboptimal conditions diminish the angiotensin converting enzyme(ACE)inhibition of meat digesta,their antioxidant activity was only negatively affected by intestinal altered conditions.