Browning and Ascorbic Acid Degradation in Meals Ready-to-Eat Pear Rations in Accelerated Shelf Life

Pears in syrup in flexible pouches are part of the U.S. Army's Meals Ready-to-Eat rations, which are expected to have a shelf life of 3 years at 26.7C. However, browning during storage was reducing the shelf life. Pear pouches were subjected to complete headspace removal and rotation during retorting for extended shelf life of 45 days at 48.9C. The pears were tested for browning, ascorbic acid and headspace composition during storage. A combination of complete headspace removal and rotation of pouches during retorting increased the acceptability of pear by decreasing ascorbic acid degradation and browning. Aerobic and anaerobic ascorbic acid degradation reactions took place in the pears, with most of the aerobic degradation beginning during retorting. A lag period of several days between different stages of ascorbic acid degradation was detected. Finally, the ascorbic acid loss followed zero-order kinetics, with a reaction rate dependent on the initial concentration. Practical Applications: This paper highlights the importance of minimizing the headspace volume during vacuum packaging and enhancing the application of heat transfer during retorting to improve the preservation of color of thermally processed pears in flexible pouches. This process also serves to reduce the ascorbic acid degradation during storage.