The study – published in the Journal of Food Science – notes that although tomato seeds are typically seen to be a low value by-product of tomato processing, they actually have great potential in producing oil with high antioxidant capability.
“To maximize the economic value of tomatoes and protect the environment, tomato processors are urgently seeking alternate uses of tomato seeds,” said the researchers, led by Zhongli Pan, who noted that such seeds contain between 20 and 36.9% oil.
“Because of the high content of unsaturated fatty acids, especially linoleic acid, tomato seed oil should be a good source of edible oil or an ingredient in cosmetics, among other uses,” they affirmed.
Pan, from the Agricultural Research Service at the United States Department of Agriculture (USDA), and his research team assessed the impact of processing conditions including time, temperature, solvent-to-solid ratio and particle size on the yield and antioxidant activity of oils extracted from tomato seed.
The researchers revealed that increasing temperature, solvent-to-solid ratio, and extraction time all improved oil yield.
The group noted that with roughly one-third of the estimated 130 million tonnes of tomato produced globally every year consumed in the form of processed products, there is a big opportunity for the utilisation of processing by-products such as seeds – which represent between 3 and 5% of the fresh tomato weight.
“Nearly 60% (1.3 million tons) of the total waste is tomato seed which is usually disposed as livestock feed with low value or is otherwise dumped in landfills,” said Pan and co-workers.
The team revealed the recommended oil extraction conditions to be 8 min of extraction time at a temperature of 25 °C, using a solvent-to-solids ratio of 5/1 (v/w) and particle size of 0.38 mm – which gave oil yield of 20.32% with recovery rate of 78.56%.
Optimal conditions and models which describe the extraction process are recommended. Pan and his colleagues said understanding the optimal conditions for extraction of the oil will provide information that is ‘vital’ for determining industrial scale extraction processing conditions for the large-scale production of a high quality tomato seed oil.
Source: Journal of Food Science
Published online ahead of print, doi: 10.1111/j.1750-3841.2012.02804.x
“Study of Optimal Extraction Conditions for Achieving High Yield and Antioxidant Activity of Tomato Seed Oil”
Authors: D. Shao, G.G. Atungulu, Z. Pan, T. Yue, A. Zhang, X. Li