Processing Technology Of Vacuum Freezing And Hot Air Drying Stachys Affinis Powder And Study On Powder Granules

Stachys affinis,also is known as Chinese artichoke,crosne,Dihuan Er,etcetera,mostly eat tubers,which has unique flavor,crisp taste,and high nutritional value.Stachys affinis can regulate the gastrointestinal tract and protect the liver.Stachys affinis has high water content,so it is effortless to spoil and deteriorate after harvest,which significantly reduces its nutritional value.At present,the preserved Stachys affinis is mostly maintained by curing,and the curing process is likely to cause the taste and texture of the mandarin to change much,the nutrients are seriously lost,and the existing processed products of the Stachys affinis are too simple.It is of considerable significance to develop and utilize the varieties of Stachys affinis products to improve the utilization rate of raw materials and the nutritional value of food.Therefore,to solve the problems of storage and transportation of Stachys affinis,it can be dehydrated and dried.On the one hand,it helps to improve the storability and reduce transportation costs;on the other hand,it provides technical means and theoretical basis for the industrial production of Stachys affinis dry powder products.In this paper,two drying methods are used,namely hot air drying and vacuum freeze drying,respectively,to dehydrate and dry the Stachys affinis to make powder.The characteristics of the whole Stachys affinis powder prepared by the two methods were measured,and the best drying method was obtained.Afterward,the whole powder produced by the best drying process would be optimized to get a nutritional dry powder granule with a unique flavor.The main research results are as follows:(1)Two kinds of drying processes,hot air drying and vacuum freeze drying,were used to dry fresh Stachys affinis into powder,and the optimal technological parameters of the two drying processes were determined.The results of hot-air drying research show that,while using the average drying rate and chromatic aberration as evaluation indicators,using the comprehensive scoring method to obtain the hot air drying impact value,and combined with the response surface analysis method,the most apparent impact on the total amount is the loading capacity.At the same time,the wind speed has the smallest effect.The best technological parameters were obtained:heating temperature 73?,wind speed 1.5m/s,loading capacity6.6kg/m~2.Under this technical condition,the value is the highest(0.883712),at this time,the drying effect is the best.The results of vacuum freeze-drying research show that while using the freeze-drying rate as the test index,combined with the response surface analysis method,the most apparent impact on the freeze-drying rate is sublimation drying temperature,analysis drying vacuum degree has the smallest effect.It is concluded that the lyophilization rate is the highest when the sublimation drying vacuum is 111Pa,the sublimation drying temperature is 76?,the analytical drying vacuum is 76Pa,the analytical drying temperature is 40?,and the loading amount is 7.13kg/m~2.The measured lyophilization rate is 12.752%/h.(2)Using rehydration,chromaticity,granularity,hygroscopicity and stachyose content as indicators and measuring the characteristics of the whole Stachys affinis powder,could select the best drying method.We could get a few results from the study.The rehydration property of the whole Stachys affinis powder prepared by vacuum freeze-drying was 1017%better than that made by hot air drying(831%).The chromaticity between the whole Stachys affinis powder obtained by the vacuum freeze-drying process and the fresh Stachys affinis is small.The whole Stachys affinis powder made by vacuum freeze-drying has uniform granularity.Meanwhile,the quality is more excellent,the quality of the whole powder is better than the other.The hygroscopicity of the whole Stachys affinis powder prepared by the hot air drying process is25.12%,which is higher than that of vacuum freeze-drying(18.69%).By measuring the content of the dried whole powder stachyose,it shows that the amount of stachyose lost by vacuum freeze-drying is less than the other.In summary,vacuum freeze-drying can be used as a better drying process.(3)The whole Stachys affinis powder prepared by vacuum freeze-drying is used as a raw material to develop an adjustable dry powder granule.By adding the right amount of maltodextrin,white granulated sugar,and edible salt to optimize the formula to provide the technical basis for the development of Stachys affinis products.The results of the study showed that while using the sensory score as the index and with orthogonal test optimization analysis,the optimal formula was 9%maltodextrin,20%white granulated sugar,and 0.5%edible salt.Under this process condition,the sensory score was the highest,which was 94 points.