Provitamina A en Iberoamérica: fuentes dietéticas y biodisponibilidad de carotenoides

Valoración de la bioaccesibilidad de carotenoides mediante protocolo estandarizado de digestión in vitro

Adriana Z. Mercadante

University of Campinas, Campinas, Brasil

Introduction. Considering the essential role of biodiversity for its sustainable use in food security and nutrition, the knowledge on the composition of bioactive compounds in a wide variety of both commercial and noncommercial foods is very important. However, the events that take place during the digestive transformation of food into material that can be absorbed/assimilated by the intestinal epithelium cells and presystemic metabolism (bioaccessibility/bioavailablity) must also be considered. Objective. Thus, the aim was to adapt and validate an international consensus method for determination of in vitro digestion to assess carotenoid bioccessibility in foods. Method. The in vitro digestion method developed by INFOGEST (Minekus et al., 2014) that mimicks the salivary, gastric and intestinal phases was used, although it is not specific for any type of food component. Isolation of micelles and carotenoid extraction was based on the method published by Xavier et al. (2014). Results. Simulated salivary (SSF), gastric (SGF) and intestinal (SIF) fluids were prepared. Amylase was added to SSF at pH 7 for 2 min, pepsin was used in SGF at pH 3 during 2 h, followed by addition of pancreatin and bile to SIF at pH 7 for 2 h, all maintained at 37 oC. In order to adapt the general INFOGEST method to caroteoids, tests were carried out to evaluate the influence of electrolytes in the SF and the best way to isolate the mixed micelles and to extract carotenoids. After digestion, the micellar fraction was isolated by centrifugation at 4 °C, 20000 g for 5 min. Filtration through membrane was also used to confirm that only micellar carotenoid was isolated. Carotenoids were exhaustively extracted with diethyl ether and analyzed by high performance liquid chromatography connected to diode array and mass spectrometry detectors (HPLC-DAD-MS/MS). Enzymes and SF did not have an influence on carotenoid stability. Xanthophyll ester hydrolysis was incomplete, and both free and ester forms of carotenoids were incorporated into the micelles. The results indicated that the electrolytes may affect carotenoid bioaccessibility. This fact is probably related to their influence on the ionic strength of the digesta, which can affect micelle formation and/or stability due to the formation of complexes with bile salts and fatty acids, or due to changes on enzyme activity. The carotenoid bioaccessibilty was in the expected range of 2 to 28%, depending on the matrix and carotenoid structure. Key-words: carotenoid, carotenoid ester, digestion, bioaccessibility, HPLC-DAD-MS. References: Secretariat of the Convention on Biological Diversity. Handbook of the Convention on Biological Diversity Including Its Cartagena Protocol on Biosafety, 3rd ed.; Montreal, Canada, 2005. Minekus, M., et al. A standardized static in vitro digestion method suitable for food- an international consensus. Food & Function 2014; 5:1113–1124. Xavier, A.A.O., Mercadante, A.Z., Garrido-Fernández, J., Pérez-Gálvez, A. Fat content affects bioaccessibility and efficiency of enzymatic hydrolysis of lutein esters added to milk and yogurt. Food Research International 2014; 65:171-176.