초록
본 연구에서는 서로 다른 동결조건 및 방법에 따른 우육 및 tylose의 단순하며 간편한 동결시간을 예측할 수 있는 모델을 모색하기 위하여 23개의 실험데이터를 이용하여 시료의 초기온도$(X_1)$, 시료의 두께$(X_2)$와 시료의 초기빙결점에서 동결매체 온도사이의 차의 역수$(X_3)$ 및 표면열전달계수의 역수$(X_4)$를 독립변수로 하고 동결시간(Y)을 종속변수로 설정하여 다중회귀 분석을 실시한 결과, $Y_{tylose}=3.45X_1+7642.84X_2+4642.67X_3+2946.89X_4-431.33\;(R^2=0.9568)$ 및 $Y_{beef}=0.68X_1+7568.98X_2+2430.78X_3+3293.26X_4-299.00\;(R^2=0.9897)$의 방정식을 구하였다. 본 모델은 Cleland & Earle와 Hung & Thompson의 모델과 마찬가지로 평균절대오차는 10% 수준으로, Plank, Nagaoka 및 Pham의 모델보다 정확함과 아울러 매우 간편함을 보여 주었다. 또한, 우육 및 tylose의 $6{\sim}7^{\circ}C$ 범위에서의 열확산율은 $4.43{\times}10^{-4}m^2/hr$ 및 $4.39{\times}10^{-4}m^2/hr,\;-10{\sim}-12^{\circ}C$에서의 열확산율은 $2.42{\times}10^{-3}m^2/hr$ 및 $3.32{\times}10^{-3}m^2/hr$로 측정되었고, tylose 및 우육의 빙결점은 각각 $-0.6^{\circ}C$ 및 $-1.2^{\circ}C$로 나타났다. 그리고 표면열전달계수는 송풍식에서 무포장시 $20.57\;W/m^2^{\circ}C$, wrap 포장시는 $16.11\;W/m^2^{\circ}C$, wrap 과 Al-foil로 포장한 경우에는 $13.07\;W/m^2^{\circ}C$로 계산되었으며, 침지식은 송풍식보다 냉각속도가 약 10배 이상 빠르게 나타났다.
To develop simple and accurate analytical method for freezing time prediction of beef and tylose under various freezing conditions, freezing time (Y) was regressed against the reciprocal $(X_3)$ of difference of initial freezing point and freezing medium temperature, reciprocal $(X_4)$ of surface heat transfer coefficient, the initial temperature $(X_1)$ and thickness $(X_2)$ of samples which should cover most situations arising in frozen food industry. As results of the multiple regression analysis, equations were obtained as follows. $Y_{tylose}=3.45X_1+7642.84X_2+4642.67X_3+2946.89X_4-431.33\;(R^2=0.9568)$ and $Y_{beef}=0.68X_1+7568.98X_2+2430.78X_3+3293.26X_4-299.00\;(R^2=0.9897)$. These equations offered better results than Plank, Nagaoka and Pham's models, shown in satisfactory agreement with models of Cleland & Earle and Hung & Thompson when were compared to previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results. Also, thermal diffusivities of beef and tylose were measured as $4.43{\times}10^{-4}m^2/hr$ and $4.39{\times}10^{-4}m^2/hr$ at $6{\sim}7^{\circ}C$, $2.42{\times}10^{-3}m^2/hr$ and $3.32{\times}10^{-3}m^2/hr$ at $-10{\sim}-12^{\circ}C$. Initial freezing points of beef and tylose were $-1.2^{\circ}C\;and\;-0.6^{\circ}C$, respectively. Surface heat transfer coefficients were estimated $20.57\;W/m^2^{\circ}C$ with no-packing, $16.11\;W/m^2^{\circ}C$ with wrap packing and $13.07\;W/m^2^{\circ}C$ with Al-foil packing, and the cooling rate of immersion freezing method was about 10 times faster than that of air blast freezing method.
(Korea Food Research Institute)
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