In order to develope nutritional and flavoring intermediate product, the optimal processing conditions, functional-nutritional components and flavor enhancement by reaction flavoring for conger eel extract from low-utilized frozen small conger eel and...
In order to develope nutritional and flavoring intermediate product, the optimal processing conditions, functional-nutritional components and flavor enhancement by reaction flavoring for conger eel extract from low-utilized frozen small conger eel and byproduct such as head and fish frame were investigated.
The moisture, crude protein, and volatile basic nitrogen (VBN) contents in muscle and head of conger eel were 72.0∼76.1%, 13.5∼17.2% and 14.2∼19.2 mg/100 g, respectively. Muscle of large sized conger eel was higher in crude protein content, and lower in moisture content than those of small sized conger eel and head. And VBN content was higher in head than in muscle of conger eel. In fatty acid composition of total lipid, the major fatty acids were generally 14:0, 16:1n-7, 18:0, 18:1n-9, 20:5n-3 and 22:6n-3, and total amino acid content in muscle and head of conger eel were 15,609.4∼17,422.6 mg/100 g, 13,011.9 mg/100 g, respectively, and major ones are Glu, Asp, Leu, Lys, Ile and Arg.
3 kinds of conger eel extracts, such as hot-water extract (95℃, 10hours), hydrocooked extract (110℃, 4hours) and 2 stage enzymatic hydrolysate from muscle, head and fish frame of conger eel were prepared, and examined quality characteristics of these extracts. Free amino acid contents of hot-water, hydrocooked extract and enzymatic hydrolysate were 1,283.3∼1,864.8 mg/100 mL, 1,343.3∼2,509.4 mg/100 mL, 2,352.2∼3,613.1 mg/100 mL, respectively, and major ones are generally Asp, Glu, Gly, Ala, Leu, Lys and Arg. The contents of inorganic ion in conger eel extracts were rich in Na, K, P and Ca in order, and these ion contents were significantly different according to extract method. But contents of other taste components such as ATP related compounds, total creatinine and TMAO were not significantly different. From the results of sensory evaluation, enzymatic hydrolysate was superior to other extracts on the aspects of yield, organoleptic taste such as umami intensity and over-all acceptance.
Contents of chondroitin sulfate in hot-water, hydrocooked extract and enzymatic hydrolysate were 86.3∼128.3 mg/100 mL, 121.7∼186.7 mg/100 mL and 50.0∼111.7 mg/100 mL, respectively, and were higher in head than in muscle of conger eel. Also enzymatic hydrolysate of conger eel revealed very higher Angiotensin-Ⅰconverting enzyme inhibition ratio (82.1∼85.9%) than those of hot-water and hydrocooked extract.
Optimal substrates and reaction conditions were studied to develop conger eel extract flavor by Maillard reaction under model system. Sugar for reaction was glucose, and amino acids were cystine, glycine, alanine as the reaction substrate. And four-dimensional response surface methodology was used for monitoring dynamic changes in substrates during Maillard reaction. To develop a flavor enhancement by Maillard reaction, hydrocooked conger eel extract was reacted with precursors. 2 kind of complex substrates, such as 0.2 M glucose-0.2 M glycine-0.2 M cystine (2:1:1, v/v) solution and 0.2 M glucose-0.2 M alanine-0.2 M cystine (2:1:1, v/v) solution were selected as suitable reaction system for masking of fishy odor and reappearance of boiled meaty flavor. Hydrocooked conger eel extract and the selected precursors were reacted in a high pressure reactor to optimize reaction parameter, such as temperature, time, and pH. Optimum reaction condition were 160℃ reaction temperature, 100minutes reaction time and pH 6.8∼7.3. Four-dimensional response surface methodology indicated such as reaction time during Maillard reaction was the most influential factor, while pH of reaction system little affected in response variables such as color, nutty odor, masking of fishy odor, and boiled meaty odor during Maillard reaction.