本試驗探討以鯖魚製造魚精及其相關之產品。結果發現鈣鹽及鈉鹽對魚肉蛋白質之萃取皆有助益且隨離子濃度增加而有增加的趨勢。同時發現低溫(<50.degree.C)萃取可得到較高量之蛋白質,但所得之魚精萃取液在加熱去除油脂時會產生凝膠現象,經DSC分析發現,是鯖魚肉在冷凍儲存的過程中發生蛋白質降解所致。此外,在高溫(120.degree.C)及低溫(50.degree.C)萃取之收率皆以0.03M NaCl、pH6組最高;而TCA可溶性氮含量則低溫組較高溫組為佳,另經由胺基酸分析結果知而魚精之游離胺基酸則以His及Tau為主。< 在不同pH值(3.5-9.1),以含有2% NaCl或0.5% CaCl/sub 2/及兩者混合之緩衝溶液,在37.degree.C振盪下進行鯖魚肉之萃取,結果顯示,鯖魚肉以0.5% CaCl/sub 2/之添加所得效果最佳,最適pH值為4.9。另外,由鯖魚肉個別最佳自家消化條件之K值分析結果可知鯖魚肉自家消化的時間應以6小時為限;而萃取所得核酐酸量,均質組皆較未均質組為高,也以6小時為一時間限制,所得IMP與Inosine量最高,而萃取出苦味物質Hypoxanthine量最低,故可藉由此結果並考慮其風味成分間的相互關係,以決定鯖魚自家消化製品中核酐酸及其降解相關化合物之組成,進而掌握使產品得到最佳風味的條件。Fish essence and its related products produced from mackerel was studied. Protein extractions were carried out at either pH 6.0 or pH 8.0 for 10 min. at temperature ranging from 5 to 120.degree.C with the addition of Na salt. Results showed that more protein was recovered at pH 8.0 and as the temperature lowered. However, essence extracted at temperature 50.degree.C or below would gelatinize during subsequent heating which is necessary for clarifying and pasteurization purposes which made it unsuitable to operate below 50.degree.C. DSC suggested that this may be due to a partial degradation of myosin head during a prolong frozen storage of the mackerel. TCA soluble nitrogen was significant higher for sample extracted at 50.degree.C. Thus, the highest yield of fish essence extraction was found to be at pH 6.0, 50.degree.C with the addition 0.03M NaCl. Results of amino acid analysis suggested that fish essence has significantly higher Histidine and Tauine content.< Endogenous protease hydrolysis of muscle protein was further investigated as a modified method of preparing related products. Results showed that the highest TCA soluble nitrogen were found at pH 4.9 with the presence of Ca alone. The K value of mackerel muscle hydrolysates suggested that the time of autolysis must be less than 6hr. Both IMP and inosine were the highest with the lowest bitter tasted hypoxanthine which gives the best combination of nucleotides and there degradation products in terms of the sensory property of the product.
Fish essence broth