| Chestnut(Chinese chestnut)is a high nutritional value of tradition agricultural products,contains rich and balance nutrient content,it has high edible and medicinal value.In chestnut kernel,rich in the human body required of carbohydrates,which is given priority to with starch and soluble sugar,it contains protein,crude fat,vitamins,minerals,unsaturated fatty acids and other active ingredients,as well as the essential trace elements.In contrast to Chinese chestnut such high nutritional value,the development of Chinese chestnut industry is relatively low,this is mainly because of the difficulty of fresh chestnut storage after harvest and the technical in control.Therefore,Research to solve the key technical problems in the manufacturing process of Chinese chestnut and development diversified、convenient、delicious chestnut deep processing products is very important for the extension and development of Chinese chestnut processing industry chain.Experiment used QianXi chestnut as the raw material,discusses microwave assisted shelling technology and the effect to the PPO、color of chestnut,optimization the technology parameters of chestnut color-protecting and drying.Study the processing of baked bread and low temperature vacuum-fried and low sugar instant food by chestnut,also the analysis to product quality.The main results of experiment are as follows:1.According to the national standard,determination the basic ingredients of Chinese chestnut.Chestnut moisture content is in the range of 53 %,the protein content is about 5.62%,crude fat content is about 0.78%,total sugar content is 12.2%,starch content is 21.08%,ash content is 1.06%.2.CoMPared with the traditional hot shell,using the 35 s,520 W output power of microwave treatment can significantly improve the effect of shell and reduce the labor intensity.Open axial span length in the back of the Chinese chestnut axis can effectively enhance the effect of microwave assisted to shell.By 195 W,40 ℃microwave drying process 3 min,and then handle with 520 W high microwave power,this can shorten the time of microwave assisted to shell,improve the whole fruit rate,reduce the degree of chestnut kernel contraction degree and color change.In the length of the chestnut back axial length and heat 5 minutes,can effective to shell,but the color and quality of chestnut has markedly reduced.Microwave processing of Chinese chestnut 30 seconds in 520 W,70 ℃condition is more effectively inhibit the PPO activity than the heat treatment required at least 6 min,the same with the save of color and quality.3.The single factor effect showed that optimum concentration of VC,citric acid,EDTA-2Na and NaHSO3 is 0.4%,0.4%,0.2% and 0.15% respectively,Determined by the orthogonal test,in the best liquid ratio of VC,citric acid,EDTA-2Na and NaHSO3 which is 0.5%,0.4%,0.2%,0.15%,the color difference(Eab *)after the treatment is lowest.Lower pH is helpful to color-protect,control the solution of pH in the range of 3 is necessary.Low concentration of NaHSO3 can effectively keep the nuts’ color and brightness in the process of high temperature sterilization.4.Use hot air,microwave and lyophilization as main method,to dry Chinese chestnut after pre-treatment in the best thickness of 2 millimeters.We found that it needs 16 hours in the optimum temperature of 65 by hot air drying,and the main drying period is from ℃second hour to tenth hour.Brightness value reached 82.31 after grinding.The best condition of microwave is 260 W output power drying for 10 min,the brightness value of chestnut powder is 86.63.The chromatic aberration controlled in low level after 36 hours freeze-drying,the brightness value is on top of 93.Set 260 W of microwave output power,6 min of processing time,then 65 h℃ ot air drying for 6 hours,product quality get better by microwave-hot air drying,such as brightness value achieve in 86.67 and chromatic aberration decrease to 6.61.It’s suitable for large-scale processing.Frozen-hot air drying,first,freeze drying of 12 hours to make moisture content drop to 15%.Second,hot air drying for 6 hours,chestnut slices water content below 4% and the brightness values is 90.57,chromatic aberration value of 4.48.Microwave-freeze drying: 260 W output power of microwave,drying 6 minutes time longer and then freeze-drying for 10 hours,the good quality of chestnut powder brightness value is 93.7 and color difference a value of 3.26.5.The thickness of the cookie which composed by chestnut powder is about 2 millimeters.The appending proportion of chestnut powder,flour and glutinous rice is 4:6:4 and control the moisture of dough at about 25%,baking conditions of heat 180 up stair,℃200 down stair,roasting 12 minutes so that we can get the best results.Swelling degr℃ ee is 2.5 and crisp extents to 3105.335 after detection.6.In the processing of low temperature vacuum fried chestnut chips,the best thickness is about from 2 to 3 millimeters and beginning after 10 hours of freezing treatment.Through the experiment,we figure the frying temperature is 95.29 ℃,the frying time is 14.05 minutes and the vacuum degree is 0.09 MPa.Brittleness is 9135.95 and oil content is 9.46% under this condition of the optimal parameter.On the other hand,we find that the oil content hasn’t decrease after 5 minutes centrifugation.The sample treatment in freezing and thawing process coMPared with the one who hadn’t,the crisp degree decreased 26%~32%,but oil content increased about 5 to 8 percentage.These are direct proportion relationship between Chestnut chips’ oil absorption rate and the initial moisture content.We can effectively reduce the rate of product oil and cut down fried process time by control of Chinese chestnut initial moisture content was 20%-30% used microwave pre-drying.7.Amylase liquefaction processing after 2 times freezing-thawing treatments can improved sugar permeability effect and inhibit the action of the starch aging.The conditions of enzyme liquid included 40 ℃water bath 60 min,pH 6.8 and liquefied 60 minutes with 0.4% enzyme concentration.In order to achieve the best effect of permeability of sugar,first stewing with 30% sugar concentration for 30 min,and then deal with one minutes by 260 W to 390 W microwave processing,finally,vacuum sugar infiltration 5 hours after 30 min vacuum circulation processing in 50% sugar concentration.After drain sugar,used 195 W microwave drying chestnut nuts 15 minutes to cut down the moisture content into 20%,then proceeding 65 hot air drying 120 minutes continue to ℃fall moisture content into 10%-15%.Thus,total drying time is about 135 minutes.Microwave power in 650 W about 20 s,can effective sterilization and maintain the product quality.Above all,product breakage rate below 10%,difference value of sugar is about 8.1,brightness value is 70.03. |
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