The Effect Of Extrusion Processing On Oil Physicochemical Properties And Structure In Puffed Food

With the development of food processing technology, the extrusion processing technology has been more mature and the proportion of extrusion food in the modern food industry became larger and larger. The requirement for the high quality food was urged as the improvement of people’s living level. It is a feasible way to intensify the puffed food quality by replacing the hydrogenated oil with healthy and nutritive vegetable oil. The operating parameters in the extrusion process, types of raw materials have significant influence on the interaction between the components, sensory quality, physical and chemical properties of final products. Therefore this paper built the starch /oil /water simulation system of puffed food to investigate the effect the extrusion parameters and starch types on the Relative Saturation, conductivity, colour, peroxide value, Anisidine value, conjugated diene value, conjugated triene value of palm oil. At the same time, the antioxidant effect of antioxidants in the simulation system was discussed for scientific theory basis of the production of high quality extrusion food. The main research results are as follows:1. The barrel temperature and moisture content of raw material had significant effects on the physical and chemical properties of palm oil, and the screw rotation speed in the range of 250.00~500.00 r · min-1 had no obvious influence on the various physical and chemical properties of palm oil.2. The proportion of amylose in the extrusion process of potato starch increases which is higher than the corn starch and makes the stable structure for the combination with palm oil. Thus it offered a better protection for grease than corn starch.3. The effects of extrusion process on components and structure of palm oil are: The solid fat content deceases and the crystal structure of palm oil is destroyed; Triglycerides of palm oil undergo hydrolysis, oxidation and polymerization in various degrees; Content of unsaturated fatty acid decreased and content of saturated fatty acid increases; The heat stability of palm oil decreases; The unsaturated fatty acid is oxidized for component with O-H, C=O and conjugated diene structure and the ester bonds of triglycerides are damaged at high temperature. The content of component with O-H, CH3 and saturated fatty acid increases and the content of structure with cis-, trans- and non-conjugated C=C decrease.4. The antioxidant capacities of three antioxidants were various, the order of overall antioxidant effect is: TBHQ > BHA > BHT. The higher concentration of antioxidants, the longer the oxidation induction time, but the not linear related. When the concentration wasmore than 600 ppm, antioxidant ability remained unchanged.5. In starch/palm oil system for puffed food, when the barrel temperature is 100.00 ℃, moisture content is 18.4%, screw rotation speed is 500.00 r · min-1, the peroxide value comes to the minimum with 3.73±0.46 meq/kg which conforms to the standard of GB15680-2014(≤20 meq/kg).