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

Authors: XU, SAI - South China Agricultural University; LI, JIAN - China Agriculture University; Baldwin, Elizabeth - Liz; Plotto, Anne; Rosskopf, Erin; Hong, Jason; Bai, Jinhe

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/2017
Publication Date: 1/1/2018
Citation: Xu, S., Li, J., Baldwin, E.A., Plotto, A., Rosskopf, E.N., Hong, J.C., Bai, J. 2018. Electronic tongue discrimination of four tomato cultivars harvested at six maturities and exposed to blanching and refrigeration treatments. Postharvest Biology and Technology. 136:42-49. https://doi.org/10.1016/j.postharvbio.2017.10.004.
DOI: https://doi.org/10.1016/j.postharvbio.2017.10.004

Interpretive Summary: A simple and fast technique, electronic tongue, was used to determine the taste profile of tomato samples from different cultivars harvested at different maturities. The results also indicate that the heirloom ‘Cherokee Purple’ tomatoes contained substantially higher sugar and acid levels than did the commercial cultivars. However, this cultivar had to be harvested at breaker or riper stages to achieve the high sugar and acid content. All commercial cultivars, regardless of harvest maturity, had similar sugar and acid content upon ripening.

Technical 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 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 maturities 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) contents, 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 by 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, BA, 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.