Comparative evaluation of volatile profile of tomato subjected to hot air, freeze, and spray drying

Abstract

Tomato (Lycopersicon esculentum Mill.) is an important vegetable crop cherished all over the world for consumption as a raw vegetable or as processed products. They are subjected to various drying processes to increase product stability and decrease postharvest loss. However, this can cause a loss in volatile compounds due to process conditions. Present study aims to gain an insight into the volatile profile of tomatoes when subjected to hot air, freeze, and spray drying processes. In this regard, the analysis of headspace - solid phase microextraction (HS-SPME) in conjunction with gas chromatography–mass spectroscopy (GC–MS) revealed that the volatile profile, namely compounds belonging to aldehydes, alcohols, terpenes, ketones, and furans varied greatly between the fresh and dehydrated tomatoes. The aroma of dehydrated tomato products that retained volatiles followed the following order: freeze-drying >/≥spray drying > hot air drying. An increase in contents of compounds such as dimethyl sulfide, 2-ethyl furan, hydroxymethyl furfural, acetaldehyde, and α-terpineol was found in all dehydrated products. Interestingly, compounds such as 3-methyl furan, hexanol and terpinyl acetate were found to occur only in dehydrated products. The presence of γ-undecalactone (fruity odor note) is identified for the first time in our study in fresh and all dehydrated tomatoes. From the results obtained and with chemometric analysis as principal component analysis and hierarchical cluster analysis on the volatile profile, it could be concluded that dehydrated tomatoes serve suitable products that could be extensively commercialized world-wide to achieve overall consumer acceptability.