Comparison of free/bi-axial, fixed axial, end-over-end and static thermal processing effects on process lethality and quality changes in canned potatoes

Abstract

Thermal processing as the most prevalent food preservation technique has been extensively studied and used for years. Different modes of agitation that can be employed in the canning process are characterized by relatively different, heat impacts and their associated quality changes. Hence, the main objective of this study was to evaluate the impact of different retort conditions on lethality (Fo), color and textural changes in potato cubes. Process variables employed were: retort temperature: 115, 120, 125 ºC; agitation orientations: vertical (end-over-end) and horizontal (fixed and bi-axial); agitation speed: 0 (static), 10, 20 rpm. A water immersion single basket rotary retort was retrofitted to simultaneously accommodate agitating modes of rotation. Accumulated process lethality values were calculated for each experimental run. Color quality in terms of parameters such as, yellowness (b-value), total color difference (ΔE values) and textural quality in terms of hardness values were compared for the particles processed under each condition. All process variables had a significant (p < 0.05) influence on Fo, color and texture parameters of potato particles. The quality changes were found to correlate well with the accumulated Fo values achieved during processing. As can be expected, the quality loss increased with an increase in Fo and vice versa.