Release of nutrients and exorphins during in vitro static gastrointestinal digestion of spaghetti from durum wheat

Consumption of wheat-derived products has been linked with significant nutritional and health impacts such as the management of glycaemic index and the onset of immunological reactions. Some of these phenomena relate to kinetics and degree of breakdown of wheat components during digestion. In dried pasta from durum wheat, the stability of starch and proteins to gastrointestinal enzymes has been reported to be affected by processing (especially drying cycle) and cooking. Therefore, the release of nutrients and bioactive molecules and the health impact coming from consumption of differently processed pasta may differ as well. To better understand how chemical and physical changes induced by processing and cooking affect digestibility of starch and proteins, two samples of cooked spaghetti dried under low (LT) or high (HT) temperature cycles were subjected to the in vitro static gastrointestinal digestion (SGID) according the protocol developed within the COST action FA1005. Starch swelling and denaturation/aggregation of proteins occurring at drying and cooking mainly determined different release of free amino acids (AA) and simple sugars during SGID. Indeed, at the end of SGID, the total amount of released maltotriose, maltose and glucose significantly differentiated digestates of LT and HT spaghetti (12.64 and 15.89 g 100 g-1). In the same samples, diverse amount (16.34 and 12.47 g 100 g-1 protein) of free AA was found. By means of high-resolution mass spectrometry, the release of six gluten exorphins during SGID was monitored as well. Only the exorphin C5 (YPISL) was revealed in gastric digestates of both LT and HT spaghetti. A possible bioactivity of exorphins using human intestinal cell lines is under investigation. Overall, the obtained results better address the knowledge on some digestibility and health features of LT and HT cooked spaghetti. Keywords: spaghetti, in vitro digestibility, gluten exorphins References: Fukudome S., Yoshikawa M. 1993. Gluten exorphin C. A novel opioid peptide derived from wheat gluten. FEBS Letters, 316:17-19. Reichelt K.L., Tveiten D., Knivsberg A.-M., Brønstad G. 2012. Peptides’ role in autism with emphasis on exorphins. Microbial Ecology in Health & Disease, 23:18958. Stuknytė M., Cattaneo S., Pagani M.A., Marti A., Micard V., Hogenboom J., De Noni I. 2014. Spaghetti from durum wheat: Effect of drying conditions on heat damage, ultrastructure and in vitro digestibility. Food Chemistry, 149:40-46.