Bell pepper maturity determination by ultrasonic techniques

Abstract

Ultrasonic wave attenuation within the flesh of intact greenhouse-grown pepper (Capsicum annumL.) fruits was measured during growth, to try to correlate this attenuation with quality-related physical properties: firmness, dry weight percentage (DW%) and total soluble solids (TSS) contents, and chemical composition. Twenty examples of each of three cultivars were picked weekly during a 7-week growth period, and weight, color, and ultrasonic wave attenuation were recorded, to nondestructively trace the changes during growth, and each intact pepper was then subjected to a relaxation test to determine firmness. Then, small samples of fruit flesh were destructively analyzed to determine DW% and TSS.During the 55thto the 65thday after flowering the fruits of all three cultivars reached their maximum weight, color started to change, and DW% and TSS started to increase rapidly; and the fruits were nondestructively examined by mechanical relaxation and ultrasonically. Principal component regression (PCR) analysis revealed significant (95%) correlation between ultrasonic attenuation, TSS and physical parameters. A TSS prediction model was developed for all three cultivars.