Effect of Storage Conditions on Qualities and Water Sorption Isotherm of Khanom La

Abstract

This research aimed to investigate the effects of atmospheric storage condition (at 0.33 and 0.75 water activity, aw) and storage time on the qualities of Khnom La. The sorption isotherm also was studied. The moisture content of Khanom La was adjusted using the saturated salt solution at different relative humidity levels. The sorption isotherm, hardness, color and peroxide values of Khanom La were then evaluated. The sorption isotherm data of Khanom La was fitted to BET and GAB models. The experimental result showed that monolayer values of the sample were in the range of 3.15 to 3.39 g water/ 100 g dry solids when its water activity was in the range of 0.11 to 0.84. Khanom La samples were stored in closed containers at an ambient temperature either at 0.33 and 0.75 aw for 35 days. Lightness and hardness of Khanom La decreased, while the redness yellowness and peroxide value of those desserts increased with storage time. The effects were more pronounced when samples were stored at 0.75 aw. The results indicated that crispy Khanom La might retain the desirable attributions during days of storage in a sealed container at low water activity.
 HIGHLIGHTS
 
 The major factors affecting the qualities and water sorption isotherm of Khanom La after frying are storage conditions (such as water activity of atmospheric storage environment and storage time)
 The problem of fried products is the deterioration of oil over time during storage, involving a complex pattern of the peroxide and oxidation reactions which are related to their water activity
 The hardness of Khanom La reduced, while the peroxide and chromatic values increased with an increase of water content more than the monolayer value of GAB fitting, indicating the degradation of products progressively during storage
 
 GRAPHICAL ABSTRACT