국립강릉원주대학교

초록/요약 도움말

In general, red snow crab (Chionoecetes japonicus) has been produced and distributed into frozen meats (leg and body) of meat-flake through muscle separation and packaging processes after boiling with water. The boiling process is nesessary as a pre-processing for preservation from the spoilage induced by enzymes and micro-organism, but in which some problems such as waste water, the loss of nutritional components and high energy cost have raised. However, it is very difficult ot separate the muscles from the shells of body and legs intactly without boiling process. In this context, a comparative study in nutritional value between commercial red snow crab leg-meat (with boiling process) and the leg-meat with no heating separation (NHS) method was conducted and describe in Chapter 1. In Chapter 2 and 3, the optimal condition of the NHS method for separating leg-muscle and shelf stability of the muscle were studied. In Chapter 1, three types of leg muscle treated with boiling, steaming and the NHS method and 7 commercial leg-meats were used for the comparative study in nutritional value, including proximate composition and amounts of water extractable compounds (free amino acid, organic acid and mineral). Although, the protein content was the highest in the boiled crab leg-meat and followed by in the leg-meat with the NHS method, most water extractable compounds especially free amino acid content notably higher in the NHS leg-meat than in other samples, indicated that the NHS method reduced the loss of nutritional compounds during preprocessing for leg-muscle separation. In Chapter 2, the effects of storage temperature and thawing time of the raw material on the meat quality were investigated for suggesting the optimal condition of the NHS method. Crabs were stored –20, -30, -40 and –50℃ for 2 days and thawed for either 5, 10, 20, 30 and 40 seconds. In these conditions, there were no significant differences in pH and acidity, but the volatile basic nitrogen elevated with thawing time. On the sensory acceptability including appearance, flavor and odor, the samples at –20℃ storage and 5 to 20 s thawing time were the best. To reveal the maximal storable period of the raw material at –20℃, changes in physiochemical and sensory properties of the leg-muscle during 7-wk storage were investigated. Discoloration appeared at storage 2-wk on around carapace and the leg-muscle yellowed at storage 30wk. The crude protein and free amino acid contents in leg-muscle gradually decreased with storage time. At storage 4-wk, the overall acceptance dropped below point 4 (could not consume at point 3) and notable inflection points in pH and acidity were observed. In Chapter 3, shelf stability of the leg-muscle separated by the NHS method were studied. The leg-muscle was packaged with a polyethylene film and stored at -20, 0 or 10 °C for 6 days. During 6-day storage, the pH were not changed in the leg-meat stored at -20 and 0 °C, while that of the leg-muscle stored at 10 °C increased at day 3. A considerable increase was observed in volatile base nitrogen, the values reached the spoilage value (30 mg%) with storage conditions at -20 °C and day 6, 0 °C and day 4, and 10 °C and day 3, respectively. The initial aerobic bacterial cell was counted at approximately 2 log CFU/g and increased rapidly in the leg-muscles stored at 0 and 10 °C from day 3 and day 1, respectively. The overall acceptance dropped below point-4 in the leg-muscles stored at 0 and 10 °C from day 4 and day 1 each. From the results, the NHS method was demonstrated that is effective for separating leg-muscle without loss of nutritional compounds. Regarding the optimal condition, it was suggested that the raw material should be stored at -20 °C within 2 weeks, the thawing time for the separation is within 20 sec and the leg-meat should be distributed at -20 °C within 6 days.