Preparation of ISHIRU (fish sauce) by a quick ripening process and changesin the composition of amino acids, oligopeptides and organic acids during processing

IKA-ISHIRU or IWASHI-ISHIRU, fish sauce made from either squid liver or sar dine with salt, have been produced in Note peninsula of ishikawa prefecture . But the long ripening period (about 1 or 2 years) is required to produce these ISHIRU with good quality. In this study, IKA-ISHIRU and IWASHI-ISHIRU were prepared by a quick ripening process(warmed method, 30 similar to 50% ). Changes in the composition of some chemical components of the two types of ISHIRU during processing were investigated. In the case of IKA-ISHIRU, t he production speed of total nitrogen and free amino acids increased with a n increase in temperature, whereas in the case of IWASHI-ISHIRU, a maximal production speed was obtained at 40 degrees C. These ISHIRU contained large amounts of free alanine, lysine, glutamic acid. glycine, serine and valine . The oligopeptides that mainly consisted of glutamic acid, glycine, aspart ic acid and proline existed in both IKA-ISHIRU and IWASHI-ISHIRU at all tem peratures, and the oligopeptide content of IWASHI-ISHIRU was higher than th at of IKA-ISHIRU. The contents of organic acids except pyroglutamic acid di d not show any significant difference in this method. In the quick ripening process, IKA-ISHIRU and IWASHI-ISHIRU could be prepared for 24 days at 50 degrees C and 38 days at 40 degrees C, respectively.