Electronic tongue discrimination of four tomato cultivars harvested at six maturities and exposed to blanching and refrigeration treatments

Abstract

The objective of this research was to evaluate whether an electronic tongue (e-tongue) could differentiate “taste” profiles of full ripe tomato fruit of different cultivars, harvest maturities, and exposure to refrigeration or blanching. The four cultivars included: two common commercial cultivars, ‘Tygress’ and ‘FL 47’, with round shape and firm texture; ‘Tasti-Lee’, a hybrid with high lycopene content due to the crimson gene for the premium tomato market; and ‘Cherokee Purple’, an heirloom cultivar that consistently ranked very high in taste tests. Commercially, tomatoes are often harvested at the mature green (MG) stage for the fresh fruit and food service markets, and traditional vine-ripe harvested tomatoes are generally sold directly at farmer’s markets. To assess the effect of harvest maturity on fruit flavor once the fruit are fully ripened, fruit were harvested at six maturities from MG to full red. ‘Tygress’, ‘FL 47’, and ‘Tasti-Lee’ fruit all had similar total soluble solids (TSS) and titratable acidity (TA) content regardless of harvest maturity. Nonetheless, ‘Cherokee Purple’ had much higher TSS and TA at all but the MG harvest stage. E-tongue tests not only confirmed the differences detected in TSS/TA data, but also differentiated between the three commercial cultivars, and six harvest maturities. Both refrigeration and blanching are common kitchen practices and they were tested on ‘Tasti-Lee’ fruit for which some changes in the taste profiles were found by e-tongue, especially for the refrigeration treatment. E-tongue sensors ZZ, JE, BB, HA, and JB data correlated to TSS and TA, with significantly high correlations with TSS. E-tongue profiles not only significantly related to TSS, but successfully predicted TSS.