• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.101-108
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• 1984

In order to study the optimal conditions of processing and storage for boiled and dried anchovy (Engraulis japonica) with high protein digestibility, the contents of trypsin indigestible substrate (TI) and in vitro apparent protein digestibility were determined. Peroxide value (PoV), TBA number and nonenzymatic brown pigments, that accounted for important antinutritional factors, were also measured and confirmed the relationship between those factors and formation of TI or in vitro protein apparent digestibility. The results were as follows; Samples boiled for 5 minutes showed the lower content of TI than the other samples boiled for 0.5 min. or 1 min. Hot air dried products had a lower TI content in comparison with the other dried ones such as sun dried or freeze dried products. It was revealed that the lower temperature ($8{\pm}1^{\circ}C$) did not affect to a great degree of forming TI and falling in vitro digestibility comparing to high temperature ($26{\pm}1^{\circ}C$) during storage. The lowest TI content (0.173 mg/g solid) was noted in the samples for 5 minutes and then sun drying after 56 days storage at $9{\pm}1^{\circ}C$. A rapid decrease of in vitro protein digestibility occurred within 0.5 min. of boiling and showed the value $85.3\%$. Freeze dried samples possessed the highest in vitro protein digestibility ($85.9\%$), when compared to sun dried or hot air dried products. Fat oxidation and nonenzymatic browning were proceeded with the various boiling times, drying methods and storing temperatures. It was noted that boiling for 5 minutes and freeze drying accelerate the fat oxidation significantly. More nonenzymatic brown pigments was developed in samples boiled for shorter time (0.5 min.) and that stored at high temperature ($26{\pm}1^{\circ}C$) than the other products. Therefore, fat oxidation and nonenzymatic browning assumed to be a major inhibitory reaction in enzyme digestion and those might be an important role in forming TI in boiled and dried anchovy products during processing and storage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.408-418
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• 1987

The quality of different grades of dried lavers obtained from three culture areas was evaluated and its changes during the storage at different levels of water activity were measured. Not much differences in general chemical composition between the locality was detected except some in the content of lipid and pigments. But the quality grades of dried lavers were mainly depended upon the content of protein and pigments including chlorophyll a, carotenoids, and biliproteins although there was little difference in amino acid composition of the proteins, and glutamic acid, aspartic acid and alanine were high in general. The lipid of dried lavers was composed of a high level of polyunsaturated fatty acids, particularly, of eicosapentaenoic acid which amounted to as much as a half of the total lipid, and of palmitic acid that reached a quarter depending on grades. The quality of dried layers was significantly changed by equilibrium moisture level when stored for three months at different water activities in range of 0.1 to 0.6. The loss of chlorophyll a, carotenoid, biliproteins, ascorbic acid, and browning were markedly retarded at aw 0.1 to 0.2. Oxidation of polyunsaturated fatty acids and the loss of free amino acids were also minimized at aw 0.2. Glutamic acid and methionine were reduced very fast during the storage.

• Korean Journal of Food Science and Technology
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• v.10 no.4
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• pp.387-393
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• 1978

Lipid oxidation is one of the major factors affecting on deterioration of nutritional quality in dried fish products. In this paper, the relationship between oxidized products of lipid and brown pigments, free amino acids and available lysine during the storage of dried sea eel, Muraesox cinereus, was investigated. And the inhibiting effect of antioxidant to lipid oxidation and its role to the protein quality were also discussed. From the results, TBA and carbonyl value rapidly increased while amino-N and available lysine diminished during hot air drying. This suggests that drying conditions greatly affected to the oxidation of lipid and making amino acids 'unavailable'. TBA value increased up to 20 days, and hereafter gradually diminished. Increase in TBA and carbonyl value and formation of fat oxidative brown pigment were closely related to the loss of free amino-N and available lysine. The loss of available lysine seemed to be affected by the formation of unsaturated carbonyl compounds rather than saturated carbonyl compounds. By the treatment of antioxidant, the loss of amino acids and available lysine was somewhat retarded. This may suggests that the oxidation of lipid or oxidative browning reactions are functioning to the loss of available lysine. In antioxidant treated sample, 23% of amino-N to the total amino-N in the fresh sample was lost after 20 days storage at $30^{\circ}C$ while the loss of amino-N to 39% in case of the control, and afterward the value treated to be slightly reduced or remained steady.