| Margarine,as a greater consumer product in recent years,still has board prospects for its application and development.However,traditional margarine often has some problems such as saturated and trans fatty acids,single fatty acid composition and poor nutritional properties.Although research has been conducted to increase the content of unsaturated fatty acids such as oleic acid and linoleic acid of margarines in recent years,there have been no related studies to increase the content of linolenic acid that is urgently needed by the human body.In addition,margarine products that are simply added with unsaturated fatty acids are prone to breakage,quality cracking and has other problems.Therefore,the development of high-quality linolenic margarine has a broad prospects.As a kind of oil modification technology,the transesterification technology has been widely used in the production of margarine by changing the fatty acid distribution on the fat triglyceride to change the properties of the fat without generating trans fatty acids.In this paper,the traditional edible lard oil with good plasticity and perilla seed oil rich in linolenic acid were used as raw materials.The transesterification process was optimized by using single factor and response surface.Based on the analysis and selection of the physical and chemical properties of the transesterified oils and optimization of emulsifiers,linolenic margarine with good quality was prepared,and its processing characteristics,digestibility and storage performance were evaluated.Finally,the correlation analysis and neural network model were used to discuss the correlation between the the margarine fatty acid composition,macro-physical properties and the internal crystalline network,providing a certain degree theoretical value and guiding significance for the development of nutritional margarine and improving the quality of margarine during storage and transportation.The main research was as follows:(1)With lard and perilla seed oil as raw materials,the effects of transesterification reaction temperature,reaction time and catalyst addition amount on the transesterification effect were determined.On the basis of the single-factor experiment,a three-factor and three-level response surface optimization experiment was performed.The optimizedtransesterification conditions were that the catalyst addition amount was 0.7%(w / w),the catalyst temperature was 80 ℃,and the reaction time was 1.5 h.A comparative analysis of fatty acid composition and enthalpy properties of oils before and after transesterification shows that AI and TI value of oils after transesterification were declined,nutritional value was increased.And broadened endothermic peak indicated that plasticity was enhanced.(2)Fatty acid and triglyceride composition,melting and crystallization thermograms,crystal form,micromorphology and rheological properties of the transesterified products of lard and perilla seed oil in different proportions were analyzed and evaluated.It was found that with the addition of perilla seed oil,the nutritional value of the oil increased,the yield stress and stability become worse,and the crystal network structure gradually become loose.In order that the transesterification products have good processing characteristics,moderate nutritional and functional characteristics,the transesterification products of lard and perilla seed oil at 8:2 and 7:3 had good plasticity and appropriate yield stress,stability,thixotropy,more delicate crystalline structure,and good anti-atherosclerosis and thrombosis index,it was suitable for the production of structural lipids such as nutritional healthy margarine.Finally,correlation analysis of indicators proved that there was a great correlation between the nutritional and processing properties of oils fatty acid and triglyceride composition,which can provided a reference for the selection of margarine base oil.(3)The blender design experiment was used to optimize the emulsifier formula,taking the water absorption and caseability as indicators.It was found that the optimized emulsifier formula were that Span-60 was 31.55%,Porpylene glycol fatty acid ester was26.70%,Lecithin high potency was 41.75%.Then the margarine was prepared on the basis of the optimal emulsifier formula and the best transesterified fat formula.A comparative analysis of the properties of two kinds of experiment margarine and commercial margarine showed that the content of total phenol,α-tocopherol,relative recovery rate,and β′ crystal form content of experiment margarine were significantly higher than those of commercial margarine,the modulus of elasticity was slightly lower than that of margarine,and the thixotropic ring area was not much different.Comprehensively,it can be known that experiment margarine has higher nutritional value,vbetter palatability and plasticity than commercial margarine.(4)An in-vitro simulated digestion model of margarine was established.According to the analysis of the particle size,charge characterization,microstructure,fatty acid release rate and antioxidant activity of margarine during digestion,it was concluded that the particle size of chylomicrons changed from increasing to decreasing,and eventually expanded to a smaller particle size.and the large size particles in the experiment margarine system had stronger decomposition ability than the commercial margarine..Fatty acid release rule showed that fatty acid release rate and degree of margarine were related to fatty acid chain length and unsaturation.the digestion speed of long-chain fatty acids was slower than short-or medium-chain fatty acids,and the saturated fatty acids digest was faster than unsaturated fatty acids.In addition,the antioxidant activity of experiment margarine was higher than that of commercial margarine at all stages of the digestion process.Correspondingly,the risk of harmful lipid oxidation products entering the human blood circulation system was lower.(5)A constant temperature storage model of margarine was established by storing two experiment margarines at low temperature(4 ℃)and room temperature(25 ℃)for 8weeks.The results indicated that peroxide value and acid value be found to increase,and the crystal structure was destroyed.The β′ crystal form gradually decreased,crystal clusters gradually appeared,and the crystal size gradually increased.In addition,the oxidation rate and crystal network destruction rate of margarine stored at room temperature were significantly higher than those stored at low temperature during the same storage time.The hardness of margarine slowly increased during low temperature storage,and its hardness decreased gradually at room temperature.The phenomenon of oil separation appeared in the later stage.Compared with the low temperature storage,the room temperature storage showed a greater impact on the crystal network and crystal size.Based on the storage data of two types of margarine,a high-precision artificial neural network model was established.Comparing the experimental values with the simulation values,the calculated relative average error was 0.98%.The established network had a high precision,which can be used to reflect the mapping between the macroscopic physical properties and the crystalline form of the nutritional margarine during storage,and it provide a theoretical basis for the controllable storage of nutritional margarine. |
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