Research On Low-moisture Powder Food Sterilization Device And Process Based On Superheated Steam Coupled With Electric Heating

Low-moisture powder foods such as spices,fruit and vegetable powder,and grain powder have a long production cycle.After being contaminated by microorganisms during drying,transportation,storage,and sales,it will cause food quality degradation and easily lead to food safety accidents.In order to ensure the safety and quality of low-moisture powder foods,a superheated steam coupled electric heating sterilization device was designed in this study,and chili powder was used as the research object for sterilization experiments.Low-moisture powder food sterilization process database was established,based on the features of low-moisture powder food.The main research contents are as follows:(1)A superheated steam coupled device was designed and components of it were selected,according to low moisture and granular speciality of powder food.Stirring parts of the device rotated to prevent powder food accumulated on the bottom from being burnt.Heating ring of the device provided heat to rise the temperature of powder.Superheated steam was injected into sterilization chamber to ensure the stable relative humidity.Drawbacks of the device were improved through pre-experiments.Chili powder was selected as the sample to study its heating curve.30 r/min of the stirring part and 11.02%water content of the 150 g chili powder were selected as the heating conditions of the chili powder for the subsequent experiments.(2)Bactericidal effect and sterilization kinetic model of chili powder were analyzed.The chili powder was sterilized for 0,5,10,15 and 20 min at 80,90 and100°C,respectively.The total number of colonies before and after sterilization was detected,and the microbial inactivation curves were fitted by linear,Weibull and Slogistic models.The results showed that with the increase of sterilization temperature and time,the total number of colonies in chili powder gradually decreased.After the incubation time reached 20 min at 100°C,the total number of colonies decreased by3.08 logs.By analyzing the model fitting evaluation parameters,weibull model could fit the sterilization curve of chili powder better,compared with the liner and Slogistic models.(3)The effect of different sterilization conditions on the quality of chili powder was studied.After sterilization under different conditions,the water content of chili powder decreased by 1.22%-2.96%,and the higher the temperature,the more water loss of chili powder.The difference in the colors of chili powder gradually increased with the increase of sterilization temperature and time.The L~*,a~*and b~*values of the chili powder were the smallest at 100°C sterilization for 20 mins.The comprehensive score of the chili powder with short treatment time was consistent with that of the untreated,and the temperature increase had little effect on the comprehensive score.The volatile constituent of chili powder treated with different sterilization conditions and without sterilization were deteted by GC-MS,A total of 26 volatile components was the main flavor of chili powder.PCA analysis showed that the types of volatile components of chili powder under different sterilization conditions were significantly different.(4)A low-moisture powder food sterilization process database was designed and established.Existing data and functional requirements of the database were analysised first,the conceptual model and logical structure were designed and then the functional modules of the database was determined.SQL Server was chosen as the database management system by comparing relational databases such as Oracle,Access,My SQL,and SQL Server.B/S development structure was adopted finally to establish a low-moisture powder food sterilization process database on the Web side and to realize management of user and data in the database system.