Utilization Of Tomato Seed

With the development of the trade of tomato products in the international markets, theproduction size of tomato products in Xinjiang has also been expanded continuously, and theyield of tomato seeds, as the byproducts, has been got a rise as well. However, till now mostof these seeds have been discarded, only some been used as the fertilizers or feeds. Due to alarge amount of oil and protein in the tomato seeds, especially the octadecadienoic acid andlysine, tomato seed has been regarded as a nutritious source of oil and protein.Supercritical CO₂ extraction (SC-CO₂) of oil from tomato seeds was carried out atvaried extraction temperatures, pressures, and time through single-factor and optimalexperiments. The extracted oil was analyzed for the extraction yield, the fatty acidcomposition and the quality. The results showed that the effects of the factors on theextraction yield were: extraction time > pressure > temperature. The optimum extractionconditions obtained were 30MPa for 2h at 50℃, which resulted in a yield of 96.34%.Determined by gas chromatography, the fatty acid compositions and their contents in tomatoseed oil after SC-CO₂ extraction were: C16:0, 13%;C18:0, 5.0%;C18:1, 22% and C18:2,56% respectively. Demonstrated by POV, A.V., S.V. and I.V., the qualities of the tomato seedoil extracted by SC-CO₂ were good as expected.Extraction of tomato seed protein was carried out through orthogonal and optimalexperiments. The optimal conditions of protein extraction were found to be: extracted atpH8.5, 50℃ and 1:50(w/v) for 30min, then precipitated at pH4.5 with HCl, readjusted pH to8.5, and dried in a freeze dryer. The final experimental values were achieved as follows: totalextraction yield= 43.31%, protein content of product= 82.06%.Determinations of some functional properties and the composition of tomato seed proteinwere also taken. The results showed that the maximum NSI was 30.02% in a 5%(w/v) tomatoseed protein solution at 50 ℃. The emulsifying capacity and stability of the soluble tomatoseed protein were increased as the temperature rose from 30 ℃ to 50 ℃, and decreased whengetting to 60 ℃. Compared with soy isolate protein, tomato seed protein had better foamingcapacity but worse foam stability. The soluble tomato seed protein (20%w/v) gelated at98.4℃ , while with the addition of CaCl2, the temperature gelated reduced. The amino acidcomposition of tomato seed protein indicated that it can be used as a promising source forsupplementation to low lysine foods. SDS-PAGE revealed that the water and salt fraction oftomato seed protein primarily exhibited three bands each (39.2, 30.1 and 15.8kDa, 66.1, 28.1and 16.8kDa, respectively), and alcohol showed two bands (30.3 and 17.8kDa).In the application of tomato seed protein to the bread, the decrease of the bread volume,the reduction of the loss of the water, the hardness and the springiness were observed, so thattomato seed protein stayed the aging of the bread. 4%(w/w) tomato seed protein has not donesignificant effects on both the flavor and the color of the bread, but intensified much in breadnutrition by increasing the contents of the essential amino acids.