Study On Low Cholesterol Lard-based Baking Shortening

Due to its unique flavor and easy digestive properties, lard has a long edible history in China and is very popular with Chinese people. However, with the improving of people's living standard , lard gradually became less and less accepted because of its high cholesterol content and bulky crystal.The purpose of this paper is to develop a low cholesterol lard-based baking shortening and solve the problem of lard resources surplus by studying the refining and deep processing techniques of lard.Firstly,this paper improved the lard refining process and compared the effect of 95% ethanol, activated Earth, activated carbon, silica gel andβ-cyclodextrin (β-CD) on removing cholesterol from lard. The results showed that the cholesterol removal rate ofβ-CD was the best. Furtherly, the effect ofβ-CD on removal of cholesterol during the lard refining and stability of lard were studied . The study results showed that during the refining process free fatty acids content had important effect on the removal of cholesterol.The cholesterol removal rate decrease as the free fatty acid content increase; The cholesterol removal process ofβ-CD reduced the content of free fatty acid and peroxide in lard, and strengthened the stability of lard. Combined with industry practice, it is better to add the cholesterol removal process ofβ-CD after degumming and deacidification of lard. Since the quality of lard andβ-CD are varied at home and abroad, this paper optimized the cholesterol removal process ofβ-CD by uniform design method and obtained the best conditions: reaction temperature 59 oC,β-CD 5.79% , reaction time 89 min. Under this condition, the cholesterol removal rates was up to 96% . Theβ-CD release rate ofβ-CD- cholesterol complex compound was also optimized, and got the optium conditions: pH9.5, ethanol concentration of 95%, mixing speed of 200 r/min and reflow time of 40 min. Under the optium conditions theβ-CD release rate was up to 95.3%. The results revealed that the embedding capability of the recyclingβ-CD was as effective as before.Secondly, baking shortening produced by enzymatic interesterification using lard and palm stearin as raw materials was studied and the influence of temperature, enzyme addition and reaction time were also discussed. The reaction equilibrium conditions were as follows: temperature of 60 oC, enzyme addition of 8% and reaction time of 1 h. After interesterification, the compatibility of mixed fats got better; SFC curve became smoother; crystalline transformed fromβtoβ′primarily and crystallization got more uniform. Besides, the triglyceride and fatty acid composition before and after interesterification were compared, and found that the asymmetric TAGs increased significantly, there was no change in fatty acid and no trans fatty acid was formed.Finally, the quality of shortening before and after interesterification was evaluated . The results showed that shortening after interesterification had better air-absorbing capacity, and could produce better quality baking bread.