Tomato By-Products

Tomato processing generates a large amount of pomace as a low-value by-product that is primarily used as livestock feed or disposed of in landfills. We developed effective separation methods of the peels and seeds of tomato pomaces from hot and cold break processes and investigated the chemical and nutritional characteristics of the peels and seeds. Tomato seeds separated from the pomace contain valuable oil and protein with unique functional properties. Different methods of oil extraction from tomato seeds were investigated, and the effects of oil quality and physiochemical properties were characterized. We also studied the impact of industrial hot and cold break tomato processes on protein isolation from defatted tomato seed meal and determined the functionality of proteins from defatted and non-defatted seed meals. The in vivo cholesterol-lowering effects of tomato pomace, tomato seed oil, and defatted tomato seed were also studied using the male Golden Syrian hamsters.

Main findings:

  • Tomato pomace can be dry or wet separated and used to produce value-added products with high nutrients.
  • The yield of oil chemically-extracted from tomato seed increased with temperature and solvent-to-solid ratio, a longer extraction time, and a smaller particle size.
  • High temperature of hot break process denatured the protein, resulting in the lower protein extraction yield from defatted hot break tomato compared to from defatted cold break tomato seed under various extraction conditions.
  • Hot break process also significantly influenced protein-related functional properties of seed meals. Defatted hot break tomato seed had higher water absorption capacity and oil absorption capacity, but lower emulsifying ability, emulsifying stability, foaming capacity, and foaming stability.
  • Defatted tomato seed had hypocholesterolemic properties and could be a food ingredient that prevents cardiovascular disease.

Related publications:

Shao, D. C. Venkitasamy, X. Li, Z. Pan, J. Shi, B. Wang, H. Teh, and T.H. McHugh. 2015. Thermal and storage characteristics of tomato seed oil. LWT – Food Science and Technology. 63:191-197.

Shao, D., G.G. Atungulu, Z. Pan, Y. Yue, A. Zhang, and Z. Fan. 2014. Characteristics of isolation and functionality of protein from tomato pomace produced with different industrial processing methods. Food and Bioprocess Technology: An International Journal. 7(2):532-541.

Shao, D., G.G. Atungulu, Z. Pan, T. Yue, A. Zhang, and Xi Chen. 2013. Separation methods and chemical and nutritional characteristics of tomato pomace. Transactions of the ASABE. 56(1):261-268.

Shao, D., W. Yokoyama, G. Bartley, Z. Pan, H. Zhang, and A. Zhang. 2013. Plasma and hepatic cholesterol-lowering in hamsters by tomato pomace, tomato seed oil and defatted tomato seed supplemented in high fat diets. Food Chemistry. 139:589-596.

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