Effect of thermal treatments on soluble-free, soluble-conjugated, and insoluble-bound phenolic components and free radical scavenging properties of tomato seeds

Authors: LI, YANFANG - University Of Maryland; WU, KATHERINE - University Of Maryland; LIU, ZHIHAO - University Of Maryland; He, Xiaohua; Sun, Jianghao; ZENG, MELODY - University Of Maryland; LEE, SEONG-HO - University Of Maryland; Wang, Thomas - Tom; GAO, BOYAN - Shanghai Jiaotong University; XIE, ZHUOHONG - University Of Maryland; WEI, CHENG-I - University Of Maryland; YU, LIANGLI LUCY - University Of Maryland

Submitted to: ACS Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2022
Publication Date: 10/5/2022
Citation: Li, Y., Wu, K., Liu, Z., He, X., Sun, J., Zeng, M., Lee, S., Wang, T.T., Gao, B., Xie, Z., Wei, C., Yu, L. 2022. Effect of thermal treatments on soluble-free, soluble-conjugated, and insoluble-bound phenolic components and free radical scavenging properties of tomato seeds. ACS Food Science and Technology. 2(10):1631-1638. https://doi.org/10.1021/acsfoodscitech.2c00228.
DOI: https://doi.org/10.1021/acsfoodscitech.2c00228

Interpretive Summary: This study investigated the effects of thermal treatments (steaming and baking for different time) on the chemical compositions, total phenolic content, and free radical scavenging activities of soluble free, soluble conjugated and insoluble bound fractions of tomato seeds. Thermal treatment significantly altered the release of the phenolic compounds in different phenolic fractions from tomato seeds. Compared with the raw tomato seeds without thermal treatments, steaming for 60 min significantly increased the TPC value in the soluble conjugated phenolic fraction and ABTS, DPPH and ORAC values in the soluble free and soluble conjugated phenolic fractions, whereas had no prompt effects on these values of the insoluble bound phenolic fractions. The results from this study may help understand the effects of thermal treatment on tomato seeds and promote their utilization as natural antioxidant ingredients.

Technical Abstract: This study aimed to investigate the effects of different thermal treatments (steaming and baking) on the chemical composition and total content of antioxidant components in soluble free, soluble conjugated and insoluble bound forms and their antioxidant properties from tomato seeds. Phenolic compositions of tomato seeds in different phenolic fractions were significantly altered after thermal treatments. Total phenolic content and free radical scavenging activities against ABTS, DPPH, and peroxyl radicals were also investigated. As compared to the raw tomato seeds, all thermal treatments had no significant effects on the total phenolic content (TPC) of soluble free phenolic fraction, however, significantly increased the TPC values of the soluble conjugated phenolic fraction. Steaming for 60 min was found significantly increased the radical scavenging activities against ABTS, DPPH, and peroxyl radicals in the soluble free and soluble conjugated phenolic fractions. All thermal treatments had no prompt effects on the TPC values and free radical scavenging activities of insoluble bound phenolic fraction. Taken together, these results indicated that thermal treatments may alter the bioactivities of tomato seeds and steaming can be a better way to obtain their health beneficial effects.