Study On The Application Of Rice Bran Oil For Frying

This text proceed several frying experiment by continuous or interval frying pattern, inwhich rice bran oil, soybean oil, palm oil and blend oil used as frying medium, and doughsticks, chips, bean curd and chicken wing used as frying ingredient. This text studied qualitychanges and retaining condition of nutritional ingredient of rice bran oil during the foodfrying process, quality changes of fried food. The text contrasted and analyzed the fryingfeatures of rice bran oil, soybean oil and palm oil, and based on this analysis, developed akind of dedicated rice bran blend oil with fine frying features to fry foods, meanwhileanalyzed it’s frying effect. In addition, this text studied the effects of different ingredients andfilter powder filtration treatment on the frying quality of rice bran oil. At last, the applicationof rapid detection of the polar component content of frying oil by conductivity method hadbeen explored.In the long(32h) and continuous frying process of dough sticks, with prolonged fryingtime, the acid value, carbonyl value, polar component, viscosity, refractive index of rice branoil all increased successively, colour deepened, iodine value decreased successively, andperoxide value increased first and reduced later; the percentage composition of saturated fattyacid(SFA%), monounsaturated fatty acid(MUFA%) and total trans-fatty acid(total TFA%) ofrice bran oil increased relatively, while polyunsaturated fatty acid(PUFA%) reduced relatively;the content of oryzanol of rice bran oil relatively stable, but phytosterol and Vitamin E allreduced, particularly severe loss of vitamin E; acid value and carbonyl value of the residualrice bran oil in fried dough sticks both increased successively, while peroxide value presenteda fluctuated increasing trend of increased first and reduced later while continue increased; thelinear relationship between the residual oil ratio of dough sticks and frying time was notsignificant; the average residual oil ratio of dough sticks was lower(12.38%), and it had goodsensory quality. The rangeability of each index (acid value, peroxide value, carbonyl value) ofrice bran oil in dough sticks was smaller than the rice bran frying oil after frying32h. Ricebran oil was rich nutrition and had good frying stability, was a good choice for frying foods.At the frying operating conditions in this experiment, compared with GB7102.1-2003“Hygienic standard of edible vegetable oils used in frying food”, the carbonyl value was 53.21meq/kg after frying for18h, exceeded the limited quantity of≤50meq/kg, which wasstated in the standard, and the total polar components was27.14%after frying for24h,exceeded the limited quantity （≤27%）. With the carbonyl value as the judgment index, thefrying life of rice bran oil should be about18h, while it should be24h with the total polarcomponents as the judgment index. Compared with GB16565-2003“Hygienic standard offried snack foods”, the carbonyl value of the residual oil in fried dough sticks was22.89meq/kg after frying for6h, exceeded the limited quantity of≤20meq/kg. The gap ofcarbonyl value Limit indicator in two standards was too big, the judgement about thecorresponding frying life displayed disagreement.Using soybean oil and palm oil to frying dough sticks under the same frying conditions,through the comparison of three frying experiment results, we found that rice bran oil hasfavorable frying characteristics, could be used to fry foods by replacing the common frying oil,such as soybean oil and palm oil, or to be a base stock of dedicated blend frying oil. Based onabove study, this text determined the optimum formula of dedicated rice bran blend frying oil:the three stage of rice bran oil50%+8degrees of palm oil40%+first grade soybean oil5%+first grade corn oil5%. This blend oil was economical and practical, had good sensoryeffect and frying performance, and high nutritive value, be appropriate for food industry anddaily family, and easily be accepted by consumers. The study found that rice bran blend oilwas preferable compared with pure rice bran oil, soybean oil and palm oil, at the aspects offatty acid composition, frying stability, nutritional, economic cost and frying foods’ sensory,etc.The text procceded intermittent frying test (cumulative frying8h) of the four typical friedfood (fried dough sticks, fries, tofu, chicken wings) which was referring to the daily operation.The study found that each physicochemical indexes (colour, acid value, carbonyl value,composition of fatty acid, content of Vitamin E)of four food ingredient(dough sticks, chips,bean curd and chicken wing) frying oils all presented significance changes with prolongedfrying time. Different frying ingredients presented different extents and types of influence onquality change of frying oil, because they contained different main components. Afterintermittent frying for8h, the increase extent of acid value of frying oil was bean curd＞chicken wing＞dough sticks＞French fries（0.57＞0.48＞0.47＞0.34）, carbonyl value was dough sticks＞French fries＞bean curd＞chicken wing（34.09＞29.12＞19.22＞14.13）, totalcontent of trans fatty acid was dough sticks＞chicken wing＞French fries=bean curd（0.22＞0.11＞0.09=0.09）, while the decrease extent of Vitamin E was French fries＞dough sticks＞chicken wing＞bean curd （64.55＞43.24＞16.94＞15.42）respectively.The frying oil in the frying process and frying old oil were processed by using filterpowder respectively, and some physical and chemical indicators of treated frying oil weredetermined. We found that filter powder was not apply to the initial frying oil, its qualityimprovement capacity was less for the old frying oil, improper filter powder processingconditions would also give rise to an additional quality deterioration of frying oil, so thefiltering effect of filter powder needs to be further explored. The degree of qualitydeterioration of frying oil in the interval progress was deeper than in the continuity progress.Quality changes of frying oil was a comprehensive reflection affected by a variety of factors,such as frying ways, frying conditions, frying ingredient.By detecting the polar components content and conductivity values of theabove-mentioned three kinds of continuity frying oils (soybean oil, palm oil, rice bran oil) ofdifferent frying time, we found that the polar component content of three frying oils waspositively correlated with the frying time, but the conductivity of frying oils fluctuated whileoverall tended to increase; the linear relationship between the polar component content andconductivity of three frying oils was not significant, and their R2were a little low withoutexception, which was0.6427、0.5468、0.6627respectively. The conductivity method couldused to rapid distinguish of frying oil and preliminary distinguish of the fried degree, but notto rapid detection of the polar component content of frying oil. What’s more, conductivitymeasurement method should be further improve and standardize.