Research On Quality Improvement Of Microwaveable Pre-fried Battered Food

The frozen pre-fried coated food is very popular among people because of itsfavourite properties, such as tender and crisp tasty,unique flavor and golden color andlong shelf life. However, the loss of its favourite tasty resulted from water migration,as well as the high content of oil, excessively limited the development of microwave-able pre-fried battered food.Based on the above reasons, the effect of substrate material, edible film layer(predust layer,batter layer,bread crumbs layer), pretreatment methods and re-heatingconditions on the quality of product was studied in this research. Mechanism of oilcontent and crispness changes of product after microwave re-heated wereinvestigated.Research and conclusion summarized as follows:1.The effect of batter formulations on product qualities were studied using color,moisture content, oil content, and crispness as indicators. Using medium-strengthwheat flour as a batter layer ingredient could improve the crispness after microwavereheating and reduce oil content of the product; The addition of crispystarch(Crispcoat868), soybean isolated protein, and guer geltin in the batter layercould improve the crisp tasty, textural property and appearance, respectively;Hydroxypropylmethyl cellulose (HPMC) could improve the viscosity of batter,strengthen the heat setting properties and adhesion characteristics of the edible film,improve the crispness after microwave reheating and reduce oil content of the product;In addition, a certain proportion of Sodium bicarbonate and Sodium acidpyrophosphate could benefit the porosity structure, hardness and crispiness ofproducts. The optimum formulation of batter layer by orthogonal experiment analysiswas listed as follows:The medium gluten content was45g/100g, Crispcoat868is45g/100g, guer gelatin is1.5g/100g, soybean isolated protein is6g/100g, HPMC is0.5g/100g, Sodium bicarbonate and Sodium acid pyrophosphate is2g/100g. 2. The paper studied the effect of the water activity of substrate material, addedblock material (gelatin) between substrate material and edible film layer andmicrowave re-heated conditions on product crispness.Results showed that when thewater activity was limited to0.890-0.905, it will lead to good crispiness. An additiveof gelatin (5%, w/w) between substrate material and edible film layer could better thecrispy tasty as well.When microwave re-heated conditions were40s at600w, thecrispy property of product was favourite.3. The effect of adding mode and content of Antarctic krill isolated protein(thewhole Antarctic krill protein isolate (whole protein), protein isolated from Antarctickrill muscle (muscle protein)), different pretreatments, frying time and fryingtemperature on oil uptake of pre-fried Coated Food were evaluated. In comparisonwith the control group (without the addition of Antarctic krill isolated protein), theaddition of Antarctic krill isolated protein was able to significantly (p＜0.05) inhibitoil uptake in pre-fried coated food. Moreover, muscle protein showed higherinhibition rate than whole protein. When5%of muscle protein or3-5%of totalprotein was added in the outermost layer of the product, the optimum reduction of oiluptake can be obtained. Combing response surface analysis with the practicality ofoperation, we got to know the optimum pre-fried condition was80s at180℃.4. The mechanism of crispness and oil content changes of product aftermicrowave re-heated was investigated. The decline in quality after microwavereheating came from moisture migration of substrate material. Low field nuclearmagnetic resonance (NMR) analysis showed that, An addition of water activitylowering agents could reduced oil content and improved crispness of the products bydecreasing the ratio of free water to middle water and inhibiting moisture migrationHigh viscosity of the batter could enchance the setting and adherence properties of thebatters and pick-up values of the products, improving its film forming property. ByDSC analysis it could be found that the Tg value of optimized-batter components was15.38℃higher than Control sample.The complex system containing polysaccharides and soy protein isolated could improve water resistance performance of edible film,so that the crispiness of the product was improved and the oil content was reduced.