The Study Of Zero-trans Acid Shortening Based On Cottonseed Oil By Intererterification

Cottonseed oil is the country’s fifth largest consumption edible oil which is rich inChina and contains large amounts of essential unsaturated fatty acids-linoleic acid, andcottonseed oil also have high nutritional value. However, cottonseed oil is sold as the cookingoil and the salad oil with low added value and small market share after oil fractionationcurrently. It has become an important issue that how to broaden the cottonseed market andenhance its value. In recent years, a sharp rise of demand for special oils has provided anopportunity for the development of cottonseed oil in the market. The experimental materialsin this paper are cottonseed oil and high melting point oil which is fractionated fromcottonseed oil; the target is to prepare the zero trans fatty acids shortening which has highermarket value by chemical intererterification.Firstly, the oil compatibility is improved of this two reaction systems after chemicalintererterification, and the oil compatibility is suitable for shortening preparation; cottonseedoil and high melting point fractionated oil are intererterificated with palm stearin respectively,and the chemical intererterification conditions are studied which are evaluated by the changeof melting point and20℃SFC before and after chemical intererterification. This paperstudies the intererterification temperature, the amount of catalyst and the intererterificationtime of this two reaction systems respectively and the optimal reaction conditions are:reaction temperature90℃, catalyst dosage0.5%, reaction time60min.Secondly, the SFC of the two systems intererterification oils compare with the SFC ofcommercial shortening and find that the ratio1:1of palm stearin and cottonseed oil and theratio1:1.25of palm stearin and high melting point fractionated oil are the best reaction ratiosafter chemical intererterification respectively whose SFC are close to the commercialshortening’s SFC.Thirdly, the crystal structure and melting feature of the two reaction oils are studied andthe results show that the two oils after intererterification get a stronger β ’ type crystal formand crystallizations are fine which are similar with the commercial shortening’s. Analysis ofthe composition of triglycerides and fatty acid composition before and after the reaction of thetwo systems can draw that the high melting point triglyceride PPO decline and reduce themelt point and SFC of systems, fatty acid composition essentially unchanged and trans fatty acids are not detected. At last， the morphology of the two reaction oils is needle-likestructure which is similar with the commercial shortening’s.Finally, the two systems choose the ratio of monoglyceride: Lecithin: Greenspan-60is0.8:0.1:0.1as emulsifier formula which regard the water absorbing capacity and airabsorbing capacity of commercial shortening as a reference by the return design experiments.Then add1%emulsifier to the two intererterification oils and prepare shortenings bylaboratory method. The two kind laboratory shortenings and commercial shortening areevaluated by bread baking separately and the three shortenings’ application functions arequite similar to bread quality.