Decrease in Available Lysine of Barley Powders during Storage at Different Water Activities and Temperatures

온도와 수분활성을 달리한 보리가루 저장시 유효 Lysine의 감소

Lysine is known as a limiting amino acid in barley and easily inactivated by the browning reaction during processing or storage. The barley powders ground to 120 mesh in particle size were controlled at water activity of 0.44, 0.52, 0.65 and 0.75 by using saturated salt solutions and then stored at 35, 45 $55^{\circ}C$. Another portion of the sample of which the water activities were controlled as same above was stored at 35, 45, and $55^{\circ}C$ alternately with 7days interval. The reaction of available lysine loss in barley powders was found to be first order. The activation energies calculated from Arrhenius plot ranged $6.02{\sim}10.32Kcal/mole$, and $Q_10$ values were between 1.34 and 1.65. These kinetic parameters were used to predict the available lysine loss of barley powders under the fluctuating temperature storage The predicted shelf-life at various water activities tested was a little higher than the actual values.

변온조건하에서 보리가루를 저장하였을 때 수분활성에 따른 avaible lysine의 손실을 반응속도론적으로 고찰한 결과 Avalilable lysine은 일차반응으로 감소하였으며 반응속도는 수분활성과 저장온도가 높을수록 빨랐고, 각 수분활성에서의 활성화 에너지는 $6.02{\sim}10.32Kcal/mole$, $Q_10$치는 $1.34{\sim}1.65$였다. Acelerated shelf-life test로부터 구한 $25^{\circ}C$에서의 shelf-life는 $60{\sim}216$일의 범위였으며 온도와 수분활성이 증가함에 따라 단축되었다. 변온조건에서의 실측치와 예측치를 비교한 결과 유효온도차는 $1.21{\sim}2.23^{\circ}C$였고 shelf-life는 실측치와 예측치가 약간 차이를 나타내었다.