외식산업용 장어류의 맛 성분에 관한 계절적 변화 연구

Abstract

Japanese eel, conger eel, hagfish and sharp toothed eel are used as the major well-being food in the foodservice industry. We investigated the consumer's recognition according to questionnaire stated below and analyzed not only the proximate composition but also the taste components affecting eels seasonal variation, which are fatty acids, nucleotides, amino acids, etc. Questionnaire: According to the investigation, 72% of the respondents answered that the most preferred was Japanese eel, and 78% made a choice of broiled eels as their favorite cuisine. Winter, about 39% answered, was the tastiest season, next was summer (32%). In particular, the respondents thought eels would greatly change their taste in summer, and the changes would be in their savory taste (31%) and texture (29%). In changes of taste, about 58% also thought Japanese eel would have a lot of changes. Comparing the cooks with the customer's, both were similar in the responses. But in respect of causes for taste change, 33% of the cooks answered it was texture and 36% of the customers it was savory taste. Proximate composition: Concerning the proximate composition, the crude lipid was the lowest in summer for each eel. Generally, the crude lipid was the highest at 11.8～13.1% in Japanese eel, and others were similar in the level. For the moisture content, Japanese eel was lower than others, marking 62.2～65.4%. The seasonal variation of their proximate composition was different in each of the eels, but they did not show a distinct difference. Fatty acid: The major fatty acids of Japanese eel, conger eel, hagfish and sharp toothed eel were C16:0, C16:1, C18:0, C18:1, C20:5 (EPA), C22:6 (DHA) and C22:5 (DPA). The C18:1 content was identified in the highest quantities among the fatty acids of eels, the content varied between 26.15% and 46.27% in Japanese eel, 36.76～45.11% in conger eel, 35.90～43.32% in hagfish and 43.98% in sharp toothed eel, respectively. Polyunsaturated fatty acids (PUFA) like DPA, DHA and EPA were identified a lot, in particular DHA, EPA in Japanese eel and conger eel, and also DPA and DHA in hagfish and sharp toothed eel. Seasonal change in the content of PUFA was increased from spring to winter in Japanese eel and conger eel, but decreased in hagfish. Nucleotide: Among nucleotides, ATP, ADP, and AMP showed a low of content but the content of IMP, HxR and Hx was high in eels. Especially, the IMP content in the Japanese eel (0.080～0.540 μmol/g) was much lower compared to that in the conger eel (3.617～5.524 μmol/g), hagfish (1.279～4.761 μmol/g) and sharp toothed eel (3.478 μmol/g). In Japanese eel and hagfish, the seasonal content of IMP was found the highest in spring and summer. Also, in conger eel, it was found in spring and autumn. Amino acid: Glutamic acid, aspartic acid, leucine, glycine and lysine were the major total amino acids; and aspartic acid, glutamic acid, serine, histidine were free amino acids. The difference in the content of amino acids was shown between eels and season. In summer, eels showed higher contents than in other seasons in both of total amino acids and free amino acids. The content of total and free amino acids detected in summer includes 51219.1, 514.2 mg/100g in Japanese eel, 79285.4, 1179.2 mg/100g in conger eel, 50342.1, 3969.5 mg/100g in hagfish and 64061.5, 949.3 mg/100g in sharp toothed eel, respectively. Consequently, total and free amino acids of Japanese eel, conger eel, hagfish and sharp toothed eel showed difference by fish variety and season. Especially the content of the said acids was the highest in summer. The content of nucleotides showed difference by fish variety and season, being generally high in spring and summer. The major fatty acids in eels were the same, but th content of PUFAs(polyunsaturated fatty acids) in eels changed by season and variety. According to the result of the analyses and questionnaires, summer are considered the most tastiest season in aspects both consumer's recognition and taste.