Estudio del contenido de compuestos bioactivos del cacao y su aplicación en la obtención de un ingrediente rico en (poli)fenoles para el diseño de un chocolate enriquecido

Abstract

ABSTRACT Currently, there is an interest in the demand for healthy foods that can have a beneficial effect on the health of consumers. The scientific evidence supports that the intake of certain compounds present naturally in foods has an inverse relationship with reduced risk of some diseases, such as cardiovascular disease, cancer and other degenerative diseases. Among the components present in food of plant origin, (poly)phenols are considered powerful antioxidants with numerous beneficial effects. Cocoa beans and their derived products are characterized by having a high content of (poly)phenols. However, numerous scientific studies have shown that from the collection of the bean to the final product, part of these bioactive compounds are lost at the different processing stages. Therefore, it is important to reduce losses of these antioxidant compounds in the final product. The overall objective of this PhD thesis has been to develop and obtain a natural cocoa ingredient with a high content of (poly)phenols and with high antioxidant capacity, which may be also suitable as an ingredient for use in food products. In the first part of the thesis, a study of the cocoa bean was performed to select the raw material with a high content of (poly)phenols. Also, the effects of various processes on the contents of (poly)phenols and flavanols were evaluated, in order to introduce new steps in the processing for the production of a defatted cocoa powder with an improved phenolic profile. This way, the industrial development of a cocoa ingredient rich in (poly)phenols and flavanols was achieved, which was then used in the formulation of a dark chocolate. The results show that the fermentation and roasting of the bean produce a significant decrease in the total content of (poly)phenols, the highest content of these compounds being observed in the "nib". The genotype CCN51 clone, produced in Ecuador, is the type of cocoa with the highest content of (poly)phenols. Inactivating the polyphenol oxidase by blanching with water at 95 °C and 5 minutes, reduced losses of (-)-epicatechin, (+)-catechin, and procyanidin B2, as well as the total content of (poly)phenols. Therefore, the use of cocoa "nib" from unfermented beans with the polyphenol oxidase inactivated seems to be a good alternative as a raw material to obtain a cocoa ingredient with an increased content of flavanols. The prototype of cocoa defatted by Soxhlet from beans with the polyphenol oxidase inactivated, represented a cocoa powder unaffected by postharvest variables. The optimum prototype was taken to pilot scale level by defatting with supercritical CO2, this resulting in a higher content of total (poly)phenols and flavanols, as well as an antioxidant capacity higher than that found in a conventional cocoa powder. The subsequent application of a heat treatment with moist heat at 121 °C during 1 minute did not affect the (poly)phenols content, obtaining a defatted cocoa ingredient with a high content of oligomeric procyanidins. Formulating a dark chocolate using 15% of this ingredient resulted in a significant enrichment of the fractions of oligomeric procyanidins, and of (-)-epicatechin, (+)-catechin and B1 and B2 dimers, when the values were compared with a not enriched dark chocolate Although the biological activity of this ingredient has not been the subject of this study, its characterization regarding its (poly)phenolic profile, open new research lines aimed at the study of the functionality of this ingredient, evaluating both in vitro and in vivo its beneficial effects related to oxidative stress mechanisms.