Comparison of peptidomic studies of simulated gastrointestinal digests from Spanish cheeses

Abstract

During cheese ripening, casein is hydrolyzed into a large variety of peptides by proteases and peptidases from milk, rennet, starter culture and secondary microbial flora. These peptides are characteristic of each cheese type and ripening time and are in part responsible of the typical and differentiating organoleptic characteristics of cheese. Some of these peptides are known to be partially resistant to digestion or they can act as precursors of the peptides that finally are absorbed. Different studies performed at our laboratory aimed the identification of the major peptides generated after two-step hydrolysis process that simulates gastrointestinal digestion of different Spanish cheeses. These include: Manchego cheese which is a hard or semi-hard variety made from ewe's milk; Serena cheese which is elaborated with ewe's milk and vegetal rennet; Tetilla cheese is made from bovine milk and animal rennet and a cheeses made from mixtures of caprine, ovine and bovine milk (Iberian and Valdeon cheeses). Therefore, the degree of proteolysis and the peptidic profile before simulated digestion was different and distinctive for each cheese type and ripening time. After digestion, the water soluble extracts were subjected to ultrafiltration through a 3000 Da membrane and the permeates were analyzed by HPLC coupled to tandem spectrometry. Many homologous sequences were found in the ultrafiltrates of the water soluble extracts although they were obtained from different cheese types. There are casein regions specially resistant to hydrolysis that were found in many of these studies such as, k¿-casein f(134-139) HLPLPL; k-casein f(47-52) DKIHPF; k-casein f(114-119) YPVEPF. Interestingly, some of the most often peptides found had been previously been reported with a given bioactivity as antihypertensive, opioid or with antiallergenic properties.