Tomato juice and sauce, and grape juice, were enhanced by the addition of soybean lecithin, with improvements noted in stability, colour, viscosity, and lycopene, phospholipid and protein content, according to findings published in Food Research International.
“Very little studies have been performed to achieve a higher level of phospholipid content in processed fruit and vegetable products, and to understand the effects of such an increase on their organoleptic and nutritional qualities,” wrote the researchers, led by Gopinadhan Paliyath from the University of Guelph in Canada.
“The addition of soy lecithin to tomato products during processing showed beneficial effects on the quality attributes of juice and sauce. Similar results may be anticipated with the use of lecithin from other sources (sunflower),” they added.
Lecithin was originally made from egg yolk, but is now more commonly made from plants and vegetables, most notably soybeans. As an emulsifier, it plays an important part in obtaining the right texture for a variety of applications, including chocolate and confectionery, margarines and spreads, bakery, beverages, convenience foods, processed meats and ice cream.
According to Euromonitor International, the global market volume of lecithin was 140,796 tonnes in 2007, and use experienced a compound annual growth rate of 2.5 per cent between 2002 and 2007. This figure relates to all uses, however, not just food.
Dr Paliyath and his co-workers supplemented tomato juice, tomato sauce and grape juice with varying levels of soy lecithin, including 0.1, 0.25, 0.5 and 1.0 g per 100mL of juice or sauce.
Results showed that the lecithin increased the protein content of the tomato sauce and juice in a dose-dependent manner. Improvements in colour were also recorded, along with increased levels of lycopene, the antioxidant pigment responsible for the red colour.
“In general, the addition of lecithin had a stabilizing effect on red pigments during processing of tomato products,” they noted.
In grape juice, however, the red colour was not significantly affected, even when the highest level of lecithin was used. The additive also did not affect the polyphenol content of the grape juice. The overall effect was different to that observed in the tomato juice, said the researchers.
“This may be due to the fact that tomato products such as juice/ sauce are rich in pectin and several insoluble components which might have interacted with soy lecithin and proteins thereby stabilizing the juice and improving the various quality parameters,” said the researchers.
“Grape juice, which is rich in soluble solids, but lacking in insoluble solids, showed lesser interactions with added lecithin. Thus, lecithin may better enhance properties of juices with a higher level of non-soluble solids,” they added.
Source: Food Research International
Published online ahead of print, 10.1016/j.foodres.2009.09.021
"Effect of soy lecithin in enhancing fruit juice / sauce quality"
Authors: M. Oke, J.K. Jacob, G. Paliyath