| In recent years,Chongqing noodles have quickly occupied the vast market of Chinese flour products market consumption and become the popular one that has swept the country.Under the "industrialization of rice and noodles staple food" has become an inevitable trend in the development of the staple food industry,the launch of the "Chongqing Good Grain and Oil" plan in 2018 has brought new opportunities for the development of Chongqing noodles.However,opportunities and challenges coexist.Chongqing noodles are mainly fresh noodles made with alkali,which is soft but not greasy in taste and without losing its "chewing strength".It has a special flavor after adding alkali and is widely welcomed by consumers.At present,commonly alkali salts used in noodles are sodium carbonate,potassium carbonate and so on,which can increase the smoothness of noodles.In addition,the moisture content of Chongqing noodles is as high as 32%,which makes the noodles easy to corruption and deterioration,and the shelf life is too short.Alkaline electrolyzed water is a by-product of acid electrolyzed water production,which has high redox potential,certain bacteriostatic effect,strong permeability,high safety and low cost.In this paper,alkaline electrolyzed water was used instead of carbonate water to study its effects on the physicochemical properties and initial bacteria carrying capacity of Chongqing noodles,and to discuss the preservation technology of extending the storage period of Chongqing noodles.The main research methods and results are as follows:1、The basic physicochemical indexes,polyphenol content,polyphenol oxidase activity and flavonoid content of two kinds of special flour for Chongqing noodles and Lanzhou pulled flour were determined.The results showed that compared with Lanzhou pulled flour,the water content of Chongqing flour was lower,with inorganic matter content of 0.531%～0.466%,crude protein content of 12.859%～13.056%,wet gluten content of 30.520%～30.553% and amylose content of 22.733%～22.819%,all of which were higher.The fat content was 1.276%～1.571%,and there were differences among the samples,but they were all within the normal proportion.Secondly,the polyphenol content of Chongqing flour was 126.785±1.773 mg GAE/100 g ～151.759±0.986 mg GAE/100 g,and the polyphenol oxidase activity was between 71.926±0.714U/g min ～ 89.037±0.898 U/g min,which was relatively high.The content of flavonoids was20.237±0.547 mg QE/100 g ～ 22.339±1.366 mg QE/100 g,and the change was not significant.2、Using potassium salts as electrolytes,this study compared the effects of alkaline electrolyzed water on the starch gelatinization properties,the thermal mechanical properties,the rheological properties and the protein structural changes of Chongqing dough with that of traditional edible alkali aqueous solution.The results showed that alkaline electrolyzed water made a lower degree of protein weakening,a significantly increase of Starch gelatinization temperature,initial gelatinization time and gelatinization enthalpy,a more orderly starch structure and an enhanced crystal thermal stability,which contributed to the improved stability of dough.As seen from the rheology test,the viscoelasticity of dough was improved,and the gluten network was strengthened by alkaline electrolyzed water.The protein composition of dough was also changed by alkaline electrolyzed water.The ratio of gliadin to glutenin was close to 1.0 in the dough prepared by alkaline electrolyzed water.The content of glutenin macropolymer increased,and the viscoelasticity of the gluten network increased.With the increase of disulfide bond content,the secondary order structure of protein increased,the gluten network became more stable and the dough elasticity enhanced.3、Using potassium salts as electrolytes,this study compared the effects of alkaline electrolyzed water on the texture properties,tensile properties,color,cooking quality and sensory evaluation of Chongqing dough with that of traditional edible alkali aqueous solution.The results showed that when alkaline electrolyzed water was added to make noodles,the adhesion of noodles decreased,the hardness,chewability,viscoelasticity,cohesion,stickiness and recoverability were improved in varying degrees,the gluten network was strengthened,the combination of protein molecules was tighter,the noodles were more elastic and smooth in taste.Secondly,the tensile resistance and distance of noodles were increased significantly,which was related to the improvement of noodle strength.With regard to noodle color,alkaline electrolyzed water noodles had the smallest change in yellow value(b* value)and color difference((35)E),and the whiteness of noodles was the highest at the end of storage.In terms of cooking quality,the rate of noodle breakage in alkaline electrolyzed water noodle was zero,and the loss of dry matter and cooking time were reduced compared with those of traditional edible alkali noodles.In the sensory evaluation,the comprehensive score of alkaline electrolyzed water noodles was 90.02±3.29 points,and its palatability,appearance,toughness,taste,color and other indicators were improved to varying degrees.4、The processing conditions and storage process of alkaline electrolyzed water noodles were analyzed and optimized,and the traditional edible alkali noodles and pure water noodles were used as the control.Through the control of fence factors such as temperature,packaging environment,preservatives,and the initial number of noodle colonies,in order to obtain the best conditions for the preservation of Chongqing noodles.The results showed that the microorganisms that caused the spoilage of Chongqing noodles included Aspergillus albicans,Penicillium,and Aspergillus niger,Gram-positive cocci,Bacillus,Gram-negative Brevibacterium.The bacteriostatic effects of alkaline electrolyzed water and glycerol monocaprylate were investigated.it was found that alkaline electrolyzed water noodle significantly reduced the total number of initial colonies and the total number of mold yeast,while 0.08% glycerol monocaprylate had the strongest bacteriostatic ability.Taking the optimized alkaline electrolyzed water with 0.08% glycerol monocaprylate noodles as the research object,the effects of packaging mode and storage temperature on the shelf life of the noodles were investigated.It was found that nitrogen gas filling after the alcohol sterilized packaging bag can effectively delay the microbial growth and acidity accumulation of noodles by controlling the storage environment,and prolong the preservation time of noodles.The storage temperature of noodles had a negative correlation with the shelf life of noodles,and the shelf life of noodles in alkaline electrolyzed water noodle can be extended to more than 12 days at 4°C.Analyzing the changes in noodle quality during storage at 4°C,It was found that the texture and tensile properties of the three water-prepared noodles showed the same trend of change,The hardness,stickiness and chewiness of noodles decreased at first and then increased,viscoelasticity decreased slightly at the beginning of storage and then kept steady,but the cohesion of noodles did not change significantly,and the maximum tensile resistance and tensile distance decreased with the increase of storage time.Finally,the best preservation technology of Chongqing noodles was obtained: alkaline electrolyzed water noodles + 0.08%glycerol monocaprylate + alcohol sterilization packaging + nitrogen-filled packaging + 4 ℃temperature storage. |
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