Evaluación in vitro de los cambios experimentados por las propiedades antioxidantes del fruto, hojas y fibra de caqui durante la digestión gastrointestinal

Abstract

[EN] The aim of this study was to analyse the changes in polyphenols, flavonoids and total antioxidant activity of persimmon fruit, aqueous persimmon leaf extract and persimmon fibres (from the peel and pulp stabilized by hot air drying or lyophilisation) throughout the gastrointestinal digestion and determine the bioaccesibility of these bioactive compounds. For that, a gastrointestinal in vitro digestion was simulated at 37ºC and under specific conditions of the steps involved in the digestion: mouth, stomach and small intestine (pH, enzymes, stirring and duration). The intrinsic effect of the pH on the digestion was also analysed by simulating digestion in absence of digestive enzymes. The results showed that the aqueous extract of persimmon leaves had higher content of antioxidants than the fruit or the extracted fibres from the peel, although it was more sensitive (higher losses) to the digestive environment. All antioxidant compounds were greater affected in the oral phase, regardless of the tested food. Acidic pH and the presence of pepsin on the stomach phase did not promote additional losses; whereas the intestinal conditions induced an increase of the soluble fraction of polyphenols and flavonoids of some matrices as a consequence of the release of the previously linked or insolubilized phenolic compounds. Thus, and at the end of the digestion, the bioactive compounds from persimmon fruit and pulp fibre, specially the lyophilized one, were more bioaccessible than those obtained from the infusion of persimmon leaf. Concretely, the bioaccesibility of polyphenols, flavonoids and antioxidant activity of the fruit was up to 1.4, 1.0 and 3.8 times the persimmon leaf at the end of digestion in presence enzymes. Finally, the digestive enzymes contributed to the preservation of all bioactive compounds throughout digestion and consequently they enhanced their bioaccesibility

[ES] El alumno evaluará los cambios en las propiedades antioxidantes de la fibra de pulpa y de piel de caqui a lo largo del proceso digestivo utilizando métodos de simulación in vitro.