Sesame lignans could be edible oil antioxidant - study

"The observed higher thermal stability of edible vegetable oils after addition of sesame lignans suggests that: sesame lignans may have potential application as natural antioxidants in the edible oil and food industry; blends of sesame oil with preferred oil(s) might increase the antioxidant potential of oils; and therefore, blending of vegetable oils with sesame oil may be more effective than the addition of synthetic antioxidants," wrote the authors in the journal Food Chemistry .

Interest is growing in plant-derived food additives as replacements to synthetic antioxidants like butylhydroxyanisole (BHA) and butylhydroxytoluene (BHT) to slow down the oxidative deterioration of food.

Indeed, according to a 2003 report by Frost and Sullivan, the synthetic antioxidant market is in decline, while natural antioxidants, such as herb extracts (particularly rosemary), tocopherols (vitamin E) and ascorbates (vitamin C) are growing, pushed by easier consumer acceptance and legal requirements for market access.

This natural antioxidant range could potentially include sesame lignans, according to promising results from scientists from Indian Council of Medical Research, Andhra Pradesh, who investigated the potential of the lignans (0.6 or 1.2 per cent) on the thermal and storage stability of soybean, sunflower and rice bran oil.

The researchers report that the oils had free radical scavenging activity prior to addition of the lignans, with rice bran and soybean oil having similar and higher activity than sunflower oil, before and after frying.

Addition of 1.2 per cent lignans increased the radical scavenging of the sunflower and soybean oils, but not the rice bran oil.

"This study demonstrates the higher radical scavenging activity of edible vegetable oils with added lignans (sesamin and sesamolin) possibly due to synergism between sesame lignans and the non-glyceride components of soy bean oil (soya lignans, isoflavanoids) or sunflower oil (phytosterols)," wrote the researchers.

"These findings suggest that sesame lignans may have potential application as natural antioxidants in the edible oil and food industry," they concluded.

Antioxidant revenues are predicted to grow from €46m ($55m) in 2004 to €58m ($70m) in 2008, according to Frost and Sullivan.

The study was financially supported by Canada-based Oleanergie F2001, a soy protein isolates and concentrates producer.

Source: Food Chemistry (Elsevier) Volume 105, Issue 3, Pages 1076-1085 "Sesame lignans enhance the thermal stability of edible vegetable oils" Authors: S. Hemalatha, and Ghafoorunissa