Sensing technology for quality assessment in controlled atmospheres

Postharvest storage conditions are important factors in determining the efficiency and profitability of fruit growing for many crops. One of the most important attributes used to assess fruit quality is firmness, which is difficult to accomplish in a closed controlled atmosphere (CA) system. The aim of this research was to evaluate the use of the fruit's acoustic response as a non-destructive technique for determining quality change during CA storage. The system used was based on identifying resonant frequencies of the fruit using flexible piezoelectric sensors. The study focused on quantitative evaluation of the change in apple quality during CA storage. 'Golden Delicious' apples from different growers, stored with and without plastic covers or with and without fogging systems, were evaluated by measuring the softening rate as indicated by the change in the fruit's acoustic response. A gradual decline in apple firmness was generally observed as storage progressed. The rate of firmness loss was greater for uncovered than for covered apples and for fruit stored without a fogging system compared with fruit stored under fogging. The rate of softening varied for fruit from different growers. The method described may provide an efficient method for detecting apple quality changes during CA storage. (C) 2003 Elsevier B.V. All rights reserved.