Process Technology Of Quick-Frozen Prepared Double-Fried Pork And Quality Change During The Frozen Storage

Quick-frozen prepared food, because of its’convenient, nutrious, delicious, health safety and diversified characteristic, will become the main direction of future consume. Currently, the market of frozen prepared food is mainly rice and flour products, but Chinese dishes are almost none. Double-fried pork has long been deeply loved by national people. This article selects Pimento Double-fried pork as experimental object, and develops it into frozen prepared food. Meat and pimento are handled separately. Meat is fried before frozen and pimento is frozen directly, when eating, mix them and heat by microwave. Separately studied the pretreament of Double-fried pork and pimento, and their quality change during the frozen storage.On the base of traditional produce method, selected fry temperature, fry time, microwave power and microwave time as factors, had sensory score as index, orthogonal experiment was carried out to determine the fry-microwave secondary cooking process. The result showed that the order of impact of every factors on quality of Double-fried pork was:microwave power>fry temperature>fry time>microwave time. When fry 4.0 min at 180℃, and microwave 3.5 min at 680 W when eating, the sensory score was the highest, and detected the texture of Double-fried pork. Studied different ratio of carrageenan and xanthan gum’s influence on Double-fried pork’s water holding capacity and texture, had drip loss, water holding capacity, texture as indexs. Considering the various indicators, the optimal ratio of carrageenan and xanthan gum was 3:7.Studied Double-fried pork’s quality change during the frozen storage. With the increase of frozen time, sensory score, springiness and water holding capacity showed a decreased tendency; hardness, cohesiveness, chewiness, thiobarbituric acid reactive substances and total volatile basic nitrogen showed a increased tendency. Carried out correlation analysis between sensory score, texture index and physicochemical index. The result showed that relation were extremely significant correlative (P<0.01). Carried out regression analysis between sensory score, texture index and physicochemical index. The result showed that the regression coefficients were extremely significant(P<0.01), and established regression equation.Studied frying’s influence on Double-fried pork’s flavor and volatile flavor compounds’ change during the frozen storage by GC-MS. Compared boiled pork and fried pork, alcohols, hydrocarbons, esters and heterocyclic compounds showed the greatest change. After frying, the kinds and relative contents of alcohols and hydrocarbons decreased; that of esters and heterocyclic compounds increased. We can see the aroma constituents of boiled pork were mainly alcohols and hydrocarbons; fried pork were mainly esters and heterocyclic compounds. Volatile flavor mainly from Maillard reaction, Strecker degradation, lipid oxidation and condiment. Aldehyde and alcohols mainly from oxidation of oleic acid, linoleic acid, arachidonic acid and condiment; heterocyclic compounds mainly from maillard reaction and oxidation of linoleic acid; hydrocarbons, sulphur-containing compounds and acids mainly from condiment.Selected 80 kinds of same flavor compounds to carry out Principal Component Analysis (PCA) with frozen time from 0 to 6. The first principal component had 73.651% contribution ratio, which characteristiced the mainly characteristic volatile flavor compounds of Double- fried pork. PCA well distinguished the Double-fried pork of different frozen time, and determined the different volatile flavor compounds which influenced Double-fried pork’s flavor of different frozen time. When no frozen, the first principal component represented the main flavor compounds. One-month frozen,1-penten-3-ol,3-methyl-l-Butanol were the mainly compounds which influenced Double-fried pork’s flavor; two and three-month frozen, mainly were Nonanal,2,4-Decadienal(E,E) and Phenylethyl Alcohol; five and six-month frozen, mainly were Hexanal and Ethanol.Through the single factor experiment and orthogonal experiment, had sensory score, frangibility, drip loss, color, peroxidase residual rate and Vc retention rate as indexs, determined the blanching, color-protecting and crisp-protecting technology. The result showed that the order of impact of every factors on quality of pimento was:blanching time> blanching temperature>ratio of material to water. The optimal blanching technology was:blanching time 40 s, blanching temperature 90℃, ratio of material to water 1:10; color-protecting and crisp-protecting technology were:had 0.6% sodium chloride solution as blanching solution, and soaked 2 h by 0.3% calcium chloride solution after blanching. Under this pretreament, pimento can contain better quality after frozen.Studied pimento’s quality change during the frozen storage. With the increase of frozen time, sensory score, frangibility and Vc retention rate showed a decreased tendency; drip loss and color aberration showed a increased tendency. Overall, pimento keeped good quality of frozen storage. Carried out correlation analysis between sensory score and other indexs. The result showed that relation were extremely significant correlative (P<0.01). Carried out regression analysis between sensory score and other indexs. The result showed that the regression coefficients were extremely significant(P<0.01), and established regression equation.The optimal microwave technology of Double-fried pork and pimento was:microwave time 4.0 min, microwave power 680 W. Under this condition, the sensory score of Double-fried pork and pimento was the highest.