Separation Methods and Chemical and Nutritional Characteristics of Tomato Pomace

Abstract

Tomato processing generates a large amount of pomace as a low-value by-product that is primarily used as livestock feed or disposed of. The objectives of this research were to investigate the chemical and nutritional characteristics and determine effective separation methods of the peel and seed of commercial tomato pomace from hot and cold break processes. The chemical composition of pomace, including fatty acid content of the seed oil, and the nutritional quality, including amino acid profile of defatted seed, were determined. The impacts of dry and wet separation on physicochemical properties of the peel and seed were evaluated. Based on the results, the studied pomace samples were rich in nutrients, including fat (8.37% to 16.24%), protein (15.08% to 22.70%), insoluble dietary fiber (IDF) (48.49% to 64.75%), soluble dietary fiber (SDF) (8.91% to 10.04%), and lycopene (98.16 to 172.07 mg kg-1). The seed oil had total unsaturated fatty acid content up to 80.10%, and the defatted tomato seed contained six kinds of essential amino acids, with histidine, an essential amino acid for infants, as the most dominant (23.34%). Both the dry and wet separation methods were effective for separation of the studied pomace. However, wet separation caused significant loss of micronutrients. The study indicated that commercial tomato pomace can be separated without water and used to produce value-added products with high nutrients.