This study investigated the quality characteristics of 5 different types of food (beef tenderloin, Japanese Spanish mackerel, radish, blueberry and tofu) by applying liquid immersion freezing, which is one of the quick-freezing methods. Each sample was refrigerated by -20℃ conventional freezing or -70℃ liquid immersion freezing respectively. After thawing at 4℃, we examined drip loss, color value, hardness, and volatile basic nitrogen. The drip loss of -70℃ freezing condition was significantly reduced compared to -20℃ freezing condition in every sample except Japanese Spanish mackerel. There were less changes in color values of beef tenderloin, Japanese Spanish mackerel, radish in -70℃ condition than conventional freezing. The hardness of beef tenderloin, tofu was decreased and that of radish, blueberry was increased at -70℃ freezing in comparison to -20℃ freezing. By applying -70℃ freezing on beef tenderloin, we also found more decreasing tendency of volatile basic nitrogen compared to -20℃ freezing. In conclusion, the quality of general frozen foods, such as beef tenderloin, Japanese Spanish mackerel and blueberry, could be improved. The possibility of developing frozen tofu is also discovered by the application of liquid immersion freezing. These results could be meaningful as baseline data for researching and development of high-quality frozen foods.

In this study, hardness, which is one of the most important texture properties of meat products, was investigated in order to evaluate the potential of using crushed meat products as food for seniors. The hardness of crushed meat products in the Korean market, such as hamburg steak (12 products), meatball (8 products), ddeokgalbi (rib patties, 13 products), and wanja (meat dumplings, 10 products) were analyzed through a texture analyzer. Also, the hardness of UDF 1st grade hamburg steak (Japanese care food) was assessed in comparison with the texture characteristics of crushed meat products. The mean value of hardness of 43 crushed meat products purchased in the Korean market was 64,733±12,319 N/m2 (23,650-102,780 N/m2) while the hardness of UDF 1st grade product was 50,910±4,990 N/m2. The hardness of 16 crushed meat products was not significantly different from that of UDF 1st grade products (p<0.05). On the other hand, crushed meat products had higher relative standard deviation (RSD, %) values of hardness (mean: 19.6%, from 7.8 to 43.1%) than the RSD of UDF 1st grade products (9.8%) except for three products. Therefore, crushed meat products could be a developable “food for seniors” if deviations of texture are minimized. These findings on texture properties could be an effective data base for the development and quality control of “food for seniors” using meat materials.

In this study, the texture, nucleotide-related compounds, and sensory characteristics of dry-aged beef, made from third quality grade Hanwoo beef (Korean native cattle), were investigated according to aging periods. Loin cuts obtained from three different Hanwoos were dry-aged under the specific conditions (controlled temperatures, humidity, and air flow) during 0-7 weeks. With increasing aging periods, textures were significantly decreased after 5 weeks (hardness: from 13,264±2,033 to 7,112±1,743 g; chewiness: from 4,107±1,467 to 2,334±780) and four sensory characteristics were significantly increased after 3 weeks (texture: from 2.2±1.0 to 6.2±1.1; flavor: from 3.9±0.7 to 6.2±1.5; whole preference: from 2.5±0.8 to 6.3±1.3; purchase intention: from 3.7±1.4 to 6.0±1.5) except for color (p<0.05). On the other hand, the concentrations of IMP which is related to the umami flavor of beef were significantly decreased with increasing aging periods (from 40.44±5.97 at 0-week to 7.44±2.43 μg/ mg at 7-week) (p<0.05). These results obtained in this study could provide an useful data base for the quality control of dry-aging.

본 연구는 냉동 오징어튀김 제품을 단체급식에서 대량튀김 조리하면서 대두유에서 발생하는 휘발성 알데히드류를 측정함으로써 대량 조리가 진행됨에 따라 발생하는 대두유의 품질저하를 평가하고자 하였다. 휘발성 알데히드류는solid phase micro-extraction(SPME)과 gas chromatography-mass spectrometry(GC-MS)을 이용하여 분석되었으며pentanal, hexanal, heptanal, (E)-2-heptenal, octanal, (E,E)-2,4-heptadienal, (E)-2-dodecenal, nonanal, (E)-2-nonenal,decanal, (E,E)-2,4-nonadienal, 4-oxononanal, 2-decenal,undecanal, (E,E)-2,4-decadienal, 2-undecenal 등 총 16가지 성분들이 검출되었다. 대조군인 미사용 대두유에서는 9가지성분들만이 소량 검출되었으며, pentanal, hexanal, (Z) or(E)-2-heptenal, (E,E)-2,4-heptadienal, (E,E)-2,4-nonadienal 등5가지 알데히드는 튀김사용 횟수 3회 이상에서 유의적으로증가하였고, (E)-2-dodecenal, nananal, (E)-2-nonenal, 4-oxononanal, (Z) or (E)-2-decenal, (E,E)-2,4-decadienal, 2-undecenal 등 7가지 알데히드는 대조군에 비해 튀김사용횟수 1회에서부터 유의적 차이를 보였으나 그 후 튀김횟수 증가에 따른 유의적 증가는 없었다.