COLOR DEGRADATION KINETICS OF REHYDRATED ‘BORLOTTO’ BEANS STORED IN DIFFERENT GAS ATMOSPHERES AS MEASURED BY IMAGE ANALYSIS

Rehydrated legume seeds represent an important ingredient for ready-to-cook fresh soups packaged in a modified atmosphere. The aim of this work was to define an image analysis system for the evaluation of ‘Borlotto’ bean color changes during storage in different gas compositions. ‘Borlotto’ bean seeds were rehydrated in water for 12 hours and stored at 5 °C in controlled atmosphere using 4 different gas compositions: 3 % O2, 10 % CO2 in air, 3 % O2 + 10 % CO2, and air as control. An algorithm in Matlab was codified to measure color of the seed red stripes and ground color (L*, a*,b*, Hue angle and Chromaticity). Sensorial analyses based on the hedonic scale (from 5=excellent to 1=very bad) of the seed appearance were also carried out. Seed color and appearance changes over time were monitored initially and after 5, 10 and 15 days of storage at 5 °C. The obtained data were used to model the quality of degradation attributes over time, that were fit into first order kinetics. A gas composition with 3 % O2 + 10 % CO2 induced the least modification on the seed ground color, which received a highest appearance evaluation up to 10 days of storage, also showing that visual appearance changes were mostly affected by the variation of the seed ground color.