Characteristics of Isolation and Functionality of Protein from Tomato Pomace Produced with Different Industrial Processing Methods

The seeds separated from tomato pomace may contain valuable protein with unique functional properties. The objectives of this research were to study the impact of industrial hot and cold break tomato processes on protein isolation from defatted tomato seed meal and determine the protein-related functional properties of defatted and non-defatted seed meals. The results showed that the high temperature of hot break process denatured the protein, resulting in the lower protein extraction yield from 9.07 % to 26.29 % for defatted hot break tomato seed (DHTS) compared to from 25.60 % to 32.56 % for defatted cold break tomato seed (DCTS) under various extraction conditions. Hot break process also significantly influenced protein-related functional properties of seed meals. Compared to DCTS, DHTS had higher water absorption capacity (WAC) and oil absorption capacity (OAC) based on the protein weight in the seed meal, but lower emulsifying ability (EA), emulsifying stability (ES), foaming capacity (FC), and foaming stability (FS) based on the whole seed sample weight. When compared to commercial soybean protein isolate (SP), the meals of hot break tomato seed (HTS), DHTS, and DCTS showed higher bulk density and WAC values. The FC and FS of tomato meals were inferior while the ES was superior to SP. High alkaline pH was beneficial to the protein extraction and achieved better EA, ES, FC and FS of all the samples. The results indicated that tomato seed meals have a great potential to be used as functional food ingredients.