Rice bran-soybean oil could offer trans-fat free shortenings: Study
Tapping into the wider industry move to reduce or remove the presence of trans-fatty acids from products, researchers Chungnam National University and Seoul National University report that a blend of fractionated rice bran oil and fully hydrogenated soybean oil, with added conjugated linoleic acid (CLA) has the potential to replace partially hydrogenated vegetable oil.
“In this study, the produced inter-esterified hard fat stock contained 12.2 to 14.2 per cent CLA, which may provide some health benefits,” wrote the researchers in the Journal of Food Science.
“On the other hand, the inter-esterified products consisted higher level of beta’ crystal form which is a desirable property of shortening. The inter-esterified products had comparable physical properties and acceptable fatty acid compositions for the shortening type hard fat stock,” they added.
Trans fats and heart health
Though trace amounts of trans fats are found naturally, in dairy and meats, the vast majority are formed during the partial hydrogenation of vegetable oil (PHVO) that converts the oil into semi-solids for a variety of food applications.
Trans fats are attractive for the food industry due to their extended shelf life and flavour stability, and have displaced natural solid fats and liquid oils in many areas of food processing.
But scientific reports that trans fatty acids raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation can cause endothelial dysfunction, and influence other risk factors for cardiovascular diseases (CVD), has led to a well-publicized bans in New York City restaurants, and other cities, like Boston and Chicago, considering similar measures.
In the food industry this has been mirrored by an increase the in pressure on food manufacturers to reduce or remove trans fatty acids from their products and reformulate.
The food industry as a whole has expressed its commitment to removing trans fatty acids from its products, but such reformulation is not straightforward and presents challenges.
Study details
The researchers, led by K.T. Lee fractionated rice bran oil into solid and liquid phases, and the former was used to produce a trans-free hard fat in combination with fully hydrogenated soybean oil with Lipozyme TL IM lipase (Novozymes). CLA was added and found to bind to the triacylglycerol (TAG) backbone of the inter-esterified products along with stearic, palmitic, and oleic acids.
When the researchers used a blend of the rice bran oil and soybean oil at a ration of 1:1.5 they obtained a blend they considered to be harder than commercial shortenings, and therefore this was the seen as the optimum blend.
“Enzymatic inter-esterification of highly saturated fully hydrogenated soybean oil with solid rice bran oil can be used as an alternative for partial hydrogenation to produce trans-free hard fat stock which is suitable for higher melting shortenings,” concluded the researchers.
Source: Journal of Food Science Published online ahead of print, February 25, 2009, doi: 10.1111/j.1750-3841.2009.01052.x“Enzymatic Production of Trans-Free Hard Fat Stock from Fractionated Rice Bran Oil, Fully Hydrogenated Soybean Oil, and Conjugated Linoleic Acid” Authors: P. Adhikari, J.-A. Shin, J.-H. Lee, J.-N. Hu, K.T. Hwang, K.-T. Lee
