In this study, the quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen beef were examined. The loin and round of second grade Hanwoo were sliced into 5-7 cm thickness and packed with aerobic packaging. The packaged beef samples, which were frozen by air blast freezing at -45 o C and electro-magnetic freezing at -55 o C, were thawed by 4 thawing methods with refrigeration (4±1 o C), room temperature (RT, 25 o C), cold water (15 o C), and microwave (2450 MHz). These samples were thawed to the point, which were core temperature reached 0 o C. Analyses were carried out to determine drip and cooking loss, water holding capacity (WHC), moisture contents and sensory evaluation. Frozen beef thawed by microwave indicated a lower drip loss (0.66-2.01%) than the other thawing methods (0.80-2.50%). Cooking loss after electro-magnetic freezing indicated 52.0% by microwave thawing for round compared with 41.8% by refrigeration, 50.1% by RT, and 50.8% by cold water. WHC thawing by microwave with electro-magnetic freezing didn't showed any difference depending on the thawing methods, while moisture contents was higher thawing by microwave with electro-magnetic freezing than refrigeration (71.9%), RT (75.0%), and cold water (74.9%) for round. The texture of sensory evaluation for round thawed by microwave result was the highest than refrigeration (4.7 point), RT (6.4 point) and cold water (6.6 point), while sensory evaluation was no significant difference. Therefore, it was shown that microwave thawing is an appropriate way to reduce the deterioration of meat quality due to freezing.

This study was carried out to investigate the effects of various temperatures of electro-magnetic resonance and air blast freezing methods on the physicochemical quality of meat. Beef (loin and round), pork (belly and ham) and chicken (breast and leg) were purchased at a commercial market, and the meat was frozen using three methods: air blast freezing (-20 o C and -45 o C) and electro-magnetic resonance quick freezing. Changes in the physicochemical properties of meat were analyzed by drip loss, cooking loss, water holding capacity (WHC) and proximate compositions. In comparison, regardless of the animal species and cuts of meat, electro-magnetic resonance quick freezing (2 h) resulted in a completely frozen product in a much shorter time than -20 o C and -45 o C air blast freezing (24 h and 8 h, respectively). Drip loss of loin which had underwent electro-magnetic resonance quick freezing were significantly (p<0.05) lower than those of the other two treatments, but cooking loss and water holding capacity were the highest at 43.7% and 60.7%, respectively (p<0.05). Characteristics such as crude protein, crude fat and moisture compositions showed significant differences, depending on the cuts and freezing methods (p<0.05). The fat composition of electro-magnetic resonance quick frozen loin and round were significantly low (p<0.05). However, moisture content was the highest compared to other freezing methods, as 67.1% and 71.9%, respectively (p<0.05). Electro-magnetic resonance quick freezing was an appropriate way to reduce the deterioration of meat quality due to freezing, and the drip loss was least for the part with low moisture, low protein, and high fat. 서 론 식품 냉동은 식품에서 열을 빼앗아 식품 내의 수분을 액 체에서 고체로 상 변화시키는 방법으로 장기 보존을 위한 최선의 방법 중 하나이다. 식육은 냉동 시 드립 발생, 단백 질 변성 및 지방 산화 등이 일어나 품질을 저하시킨다 (Lagerstedt et al., 2008; Mancini and Hunt, 2005). 특히, 식육 의 변성과 연관된 생화학적 반응은 냉동 온도에서도 액상 으로 잔존하는 식육 내의 수분 때문에 일시적으로 정지되 지만 저장 기간의 경과에 따라 진행이 지속된다 (Akamittath et al., 1990; Grujic et al., 1993). 일반적인 식육의 냉동 방 법으로는 정지 공기 냉동법(sharp freezing), 송풍식 냉동법 (air blast freezing), 접촉식 냉동법(contact freezing) 및 침 지식 냉동법(immersion freezing)이 있다. 정지공기 냉동법 은 냉각된 실내에 설치된 선반에 식품을 얹어 놓거나 또는 매달아 놓고 동결시키는 방법으로 응용 범위가 가장 넓고 관리가 용이한 반면 열전도율이 접촉식, 침지식 및 액체 질 소 냉동법보다 낮아 냉동 시간이 상대적으로 긴 단점이 있 는데 이를 보완한 것이 송풍식 냉동법이다. 송풍식 냉동법 은 냉기에 유속을 주어 공기와 시료 간에 열 전달 계수를 크게 하여 빠르게 냉동시키는 방법으로 산업적으로 가장

In this study, the physicochemical and sensory quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen pork were examined. The packaged pork samples, which were frozen by air blast freezing at −45℃ or electro-magnetic freezing at −55℃, were thawed using 4 different methods: refrigeration (4±1℃), room temperature (RT, 25℃), cold water (15℃), and microwave (2450 MHz). Analyses were carried out to determine the drip and cooking loss, water holding capacity (WHC), moisture content and sensory evaluation. Frozen pork thawed in a microwave indicated relatively less thawing loss (0.63-1.24%) than the other thawing methods (0.68-1.38%). The cooking loss after electro-magnetic freezing indicated 37.4% by microwave thawing, compared with 32.9% by refrigeration, 36.5% by RT, and 37.2% by cold water in ham. The thawing of samples frozen by electro-magnetic freezing showed no significant differences between the methods used, while the moisture content was higher in belly thawed by microwave (62.0%) after electro-magnetic freezing than refrigeration (54.8%), RT (61.3%), and cold water (61.1%). The highest overall acceptability was shown for microwave thawing after electro-magnetic freezing but there were no significant differences compared to that of the other samples.

The objective of this study was to identify appropriate aging conditions, changes in nucleotide-related compounds, chemical changes, and a sensory evaluation of duck meat during aging at 0 o C for 7 d. Twenty one 45-day-old Pekin white ducks samples were separated into breast and leg meat. ATP was not detected for almost the entire aging period because ATP was depleted immediately after slaughter. Inosine monophosphate (IMP) was highest on day 1 (26.69 µmol/g), and then it rapidly decreased to 7.11 µmol/g on day 7. However, this level was not different between breast and leg meat. Hypoxanthine (Hx) content of breast meat was 14.88 µmol/g, whereas that of leg meat was 16.41 µmol/g. Inosine content of breast meat was double than that of leg meat. The pH values of breast and leg meat were 5.90-6.05 and 6.23-6.73, respectively, during the aging period. Volatile basic nitrogen content of breast and leg meat increased during aging. Breast meat had good sensory evaluation scores for flavor (7.4), juiciness (6.8), tenderness (7.2), and overall acceptance (7.4) on day 3. Similar to breast meat, leg meat also had good sensory evaluation scores. Therefore, it is concluded that the appropriate aging period is 3 d for duck breast meat and 1 day for leg meat at 0 o C.

This study was carried out to evaluate the effect on properties of restructured jerky by the addition volume of additives. The treatments were divided into glutinous rice flour, potato starch, soybean and acorn powder. Moisture content, water activity (a w ), thiobarbituric acid reactive substances (TBARS), color, yield and sensory evaluation were performed. The moisture contents of four types of restructured jerkies were in the range of 8.92-12.47%, and were lower than that of the control (17.92%). Water activity tended to decreased with increasing addition of all treatments. The restructured jerkies containing glutinous rice flour, potato starch, soybean and acorn powder had lower TBARS than the control. The drying yield tended to increase with increasing amount of additives. In the sensory evaluation results, the highest overall acceptability was found in jerky containing glutinous rice flour, potato starch, and acorn powder when the addition was 9%, while that for soybean powder was determined to be 5%. These results suggest that 9% additions of glutinous rice flour, potato starch or acorn, or 5% soybean powder are optimal addition volumes for the preparation of restructured jerkies.