Electronic Nose for Detecting Strawberry Fruit Maturity

An electronic nose (e-nose) composed of 18 different metal oxide gas sensors was used to characterize the volatile patterns of 'Strawberry Festival' and 'Florida Radiance' strawberry fruit at five developmental stages: white, half red, three-quarter red, full ripe, and overripe. Strawberry samples were harvested at three harvest dates from early February to the end of March. Three-gram aliquots of strawberry puree were employed for headspace sampling in 10-mL vials, which were incubated at 40 degrees C for 2 min prior to analysis. Volatiles from each sample were sampled for 2 min with data acquisition every second. After analysis, there was an 18-min delay for sensor recovery. E-nose sensor data was reproducible with 90% of sensor responses having relative standard deviations of less than 10%. Sensors P30/1, T30/1, and P30/2 were the major differentiating sensors for strawberry maturity as indicated by their loadings on the first principal component (PC1). Immature and less mature fruit were well separated from full ripe and overripe fruit on PC1, regardless of cultivar. Harvest date was separated primarily by the second principal component. E-nose volatile patterns of 'Strawberry Festival' and 'Florida Radiance' strawberry cultivars were separated at identical stages of development. E-nose technology has the potential to monitor strawberry maturity and fruit quality.