| Pickled radish is a kind of common raw material for the stew in southwest area,which has unique flavor and the effect of promoting digestion.At present,products of pickled radish for stewed material have appeared in the market.This simplifies the production process of traditional dishes and provides consumers with great convenience.But at the same time,it is difficult to guarantee the flavor quality and hygienic quality.In addition,the relevant research is still stuck in the initial stage of product development.The process optimization,quality improvement and effective safety control system are still scarce.Therefore,in this paper,the experiment was started with the key links of the production of pickled radish for stewed material,to optimize the production process and control the quality of the products.Firstly,the formula of pickled radish for stewed material was optimized to improve flavor quality,the sterilization effect and sensory quality of products under different sterilization conditions were compared and the optimal sterilization condition was determined.Then,effects of different heating methods and different moisture contents on the oil samples were studied,which provided theoretical proof for the sterilization application of microwave in food containing oil.Finally,natural antioxidants were compounded to get efficient compound antioxidant formula to enhance the quality of oil in the pickled radish for stewed material and extend its shelf life,in order to provide theoretical reference for its industrial production.The main results were as follows:(1)The optimum formula of pickled radish for stewed material was obtained by uniform test design and a systematic method for sensory evaluation based on the principle of fuzzy mathematics.The optimum formula conditions were as follows: 100 kg pickled radish,35 kg water,15 kg rapeseed oil,10 kg salt,8 kg chicken oil,5 kg pickled red pepper,4 kg pickled ginger,4 kg monosodium glutamate,0.6 kg citric acid,and 0.01 kg I+G.(2)The sterilization effects on pickled radish for stewed material in different conditions of pasteurization and microwave sterilization were studied.The results showed that 80?-20 min or 90?-15 min pasteurization,560W-180 s or 700W-150 s microwave sterilization,all can achieve the ideal sterilizing effect.On the basis of the above,the effects of the sterilization conditions on the color,texture,total acid content and volatile flavor compounds were analyzed.The results showed that the L* value of pickled radish decreased,the a* and b* value increased after sterilization,degree of browning showed significant differences with control group(P<0.05),and the degree of browning of pasteurization group was significantly higher than that of microwave sterilization group,and pickled radish by 700W-150 s microwave sterilization was less affected on the overall color.What's more,the hardness of pickled radish decreased after sterilization,and hardness of pasteurization group was significantly lower than that of microwave sterilization group(P<0.05);different sterilization methods and conditions nearly has no effect on the total acid content in pickled radish.In addition,42,77 and 77 kinds of volatile components were detected separately in without sterilization,pasteurization and microwave sterilization group samples,and it was showed that volatile flavor substances of products changed through sterilization,the original components reduced but new substances formed.The new substances after sterilization were mainly alkanes,alcohols,esters and aldehydes,which can bring more flavor aroma to products.Finally,700W-150 s microwave sterilization was selected as the best sterilization condition.(3)Water bath and microwave heating treatment produced some adverse effects on the oxidation stability of oil,but there was no significant difference between the effects of two kinds of heating methods.After heating oil by 90?water bath heating for 15 min or microwave 700 W for 150 s,the relative content of chemical bonds and groups was different from the group without heating,because of glycerol ester decomposition and oxidation reaction,but the overall lipid structure did not change significantly.(4)The change of oxidation index of oil with different water content was studied.The results showed that the water content had a significant effect on the oxidation stability of oil.Compared with the oil group without water,lipid oxidation hydrolysis of two groups which had 3:3 and 3:5 oil-water ratio both intensified.After 18 days accelerated oxidation test,peroxide value and acid value were about 2.6 times and 1.2 times of the non-water group,but there was no significant difference between the two groups with different oil-water ratio(P>0.05).High moisture content may increase the risk of oxidation and hydrolytic rancidity for oil of pickled radish for stewed material.(5)The regression model between additive amount of ascorbyl palmitate,vitamin E,D-isoascorbate and the peroxide value was established by using response surface analysis method.Analysis showed that three kinds of antioxidant dosage all had significant effects on peroxide value,and there was synergistic effect between ascorbyl palmitate and vitamin E.The optimum formula of the compound antioxidant was 0.01% ascorbyl palmitate,0.05% vitamin E and 0.05% D-isoascorbate.(6)Products of pickled radish for stewed material by optimized process were stored under different temperature conditions(15?,25? and 35?)to analyze and compare the quality changes.The results showed that the total number of bacteria and the number of yeasts and moulds increased gradually during the storage period,and the growth of microorganism was slower when the storage temperature was lower.With the prolongation of time,the L* value of pickled radish decreased,the b* value increased and the a* value had no obvious change;the higher the storage temperature,the more obvious the total color difference ?E was,and the more severe the browning was.Starting from 35 d,significant differences were appeared between the hardness variation of different temperature groups(P<0.05);the hardness variation of 35? group was the most significant and the change of hardness was the lowest at 15?;and at 56 d,softening rate were 13.25%,16.43%,24.82% under the temperature of 15?,25? and 35?.The higher the degree of softening was,when the higher the storage temperature was.So reducing the storage temperature can be conducive to maintain hardness of pickled radish.The oil of pickled radish for stewed material was easier to oxidize and hydrolyze when the storage temperature was higher.The peroxide value of oil under 35? was 19.64% higher than that at 25? and 31.37% higher than that at 15? after 56 days.Meanwhile,growth rate of acid value at 35?,25? and 15? were 23.79%,18.70% and 13.29% respectively.Therefore,the temperature of 15? had the best effect on maintaining the quality of pickled radish for stewed material in the three kinds of storage temperature. |
PDF Full Text Request