Dry Fractionation Of Lard And Preparation Of Shortening

Lard is a kind of source of abundant animal fat. Because of special odor ,it iswelcome. Aeration and antioxidation of different sources are different. Lard can bechanged by hydrogenation ,interesterification ,fractionation. Fractination compared ofthe two formers is cheap and its process is simple.Especially dry fractionation iswidely used in oil and fat.Crystallization temperature, cooling rate , crystal growing time are discussed inpaper. By exploring and orthogonal test , the optimum conditions of single-step dryfractionation are crystallization temperature 21℃, cooling rate 2℃/h, residence time9h and conditions of two-step dry fractionation are crystallization temperature 16℃,residence time 30h. Olein fractions by second dry fractionation is in liquid state inroom temperature and its melting point is 11.4℃. Stearin fractions can be used as rawmaterial of margarin and shortening after deodouring.By studying on comparability , stearin fractions of lard obtained dry fractionationand hydrogenated cottonseed oil are chosen as raw materials of shortening.Emulsifiers are general glycerol monostearate , lecithin, sorbitan monostearate。Theratio of glecerol monostearate and lecithin and sorbitan monostearate is 0.8:0.1:0.1。The best constitute of shortenings is that The ratio of stearin fractions of lard andhydrogenation cottonseed oil and mixed emulsifiers is 93:6:1 and it can fulfill thefunction of shortening and curve of SFC. By response analysis, the optimumconditions of preparation are 18℃ of stock from cooling part, 406rmp of kneadingpart,4 min of agitating time.According as this process shortening is prepared,which isused in bread correspond quantong shortening obtained from market.