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Title: Study of structured lipid-based oil-in-water emulsion prepared with sophorolipid and its oxidative stability

item XUE, CHENG-LIAM - Chungnam National University
item Solaiman, Daniel
item Ashby, Richard - Rick
item Zerkowski, Jonathan
item LEE, JEUNG HEE - Chungnam National University
item LEE, KI-TEAK - Chungnam National University

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2012
Publication Date: 1/1/2013
Citation: Xue, C., Solaiman, D., Ashby, R.D., Zerkowski, J.A., Lee, J., Lee, K. 2013. Study of structured lipid-based oil-in-water emulsion prepared with sophorolipid and its oxidative stability. Journal of the American Oil Chemists' Society. 90:123-132.

Interpretive Summary: Sophorolipids (SopLip’s) are eco-friendly and biodegradable natural detergents produced by yeast. They are currently commercialized in niche-markets for use in automatic-dish-washing detergent formula and as an active ingredient in surface-cleaning solutions. We have previously demonstrated that SopLip’s can be produced by using less expensive agricultural byproducts such as soy molasses and the biodiesel-derived crude glycerol as feedstocks during fermentation, which helps lower the final production costs. Further cost reduction could be realized through economies of scale in production system, which in turn is dictated by a high demand for SopLip’s. Therefore, we constantly look for additional applications of SopLip’s to help drive up the demands. In this study, in collaboration with scientists at ChungNam National University (Korea) under a Non-Funded Cooperative Agreement, we systematically examined the use of SopLip’s in formulation of emulsion systems for food applications. We found that the natural SopLip’s are as effective as a synthetic chemical called Tween-20 that is currently used to maintain emulsion in commercial food products such as salad dressings. This finding expands the application sphere of SopLip’s, which could potentially lead to wider acceptance of this class of biosurfactants. The agricultural sector should indirectly benefit from this development through an increased demand for the agro-based feedstocks needed to produce SopLip’s.

Technical Abstract: In this study, the stability of oil-in-water (O/W) emulsions prepared with structured lipids (SLs) were evaluated in which the SLs were produced through lipase-catalyzed interesterification between soybean oil and rice bran oil. After interesterification reaction, the major triacylglycerol (TAG) species in the SLs were PLP (22.5%), PLL/OOLn (21.8%), LPL (16.1%), and LLS/PLO (16.1%), and the total amount of tocopherol and tocotrienol was 20.9 micro-g/ 100 g of SL. Sophorolipid was used as an emulsifier for preparing SL-based O/W emulsions, and the effect of pH (pH= 5.8, 7 and 7.2) on stability was studied by analyzing the fat globule size. From the results, SL-based O/W emulsions showed similar stabilities to those prepared with Tween 20 at the neutral environment. Furthermore, emulsions prepared with sophorolipid were more stable than those formulated with Tween 20 at acidic environment (pH 5.8). In the oxidation study, any antioxidant addition of propyl gallate (PG), ascorbic acid 6-palmitate (AP) or quercetin hydrate (Que) distinctively prevented peroxide formation on the SL-based O/W emulsion throughout the 23 days of storage, while AP was less effective to lower the thiobarbituric-acid-reactive-substances (TBARS) values than PG and Que.