Effect Of Key Processing Technology On Physical And Chemical Properties,quality And Energy Consumption Of Barley Grass Powder And Related Mechanism Study

Barley grass seedling is a traditional and widely cultivated agricultural resource and its seedlings contain rich nutrients and elements.Especially,flavonoids and chlorophyll inside have special significance to human health.However,for the production and storage of barley grass seedling,there are many problems,such as low chlorophyll content,microorganisms growing,high energy consumption and large particle size.These problems caused the quality decline of barley grass seedling,high processing cost,nutrient releasing difficulties;it is not conducive to human intestinal absorption.Therefore,it is necessary to study the key processing technology,including drying,crushing,moisture monitoring and sterilization/reducing bacteria.In this paper,the low energy conpsumtion,high product quality,less bacteria,sterilization and storage of barley grass were studied.The investigated technologies included microwave energy saving,processing and quality control,microbial sterilization,long storage and low field nuclear magnetic real-time moisture monitoring.The effects of microwave freeze-drying and microwave vacuum drying on the quality and energy consumption of barley grass seedling were studied.Quality of products and energy consumption of microwave freeze-drying and microwave vacuum drying were analyzed under different power level.The results showed that microwave freeze-drying and microwave vacuum drying solved the problem of high energy consumption and quality decline in the dehydration of barley grass seedling,and the most energy-saving one was microwave vacuum drying.The energy consumption and drying time of microwave vacuum drying were further reduced,compared with microwave freeze-drying.The microwave power has a great influence on the quality of product,so it is necessary to control power parameter.During the microwave freeze-drying of barley grass,the melting ice and microwave discharge should be avoided for processing failure.The water state and dynamic characteristics of the on-line and real-time moisture monitoring system of nuclear magnetism were studied in the vacuum microwave drying of barley grass seedling.By analyzing the water signal in the microwave vacuum drying of barley grass seedling,the water state and dynamic characteristics of barley grass in different drying stages were monitored.Dynamic characteristics of water fraction were also different under different power level.The fluidity of water is closely related to the quality safety and stability of product.Dynamic characteristic of water state under 200W drying are superior to that under 100/300W power.The 200W of microwave vacuum drying can not only shorten drying time but also guarantee product quality.It leads to the water state（high proportion of combined water）under which the microorganism cannot reproduce and grow.In the early stage,the characteristic of water state is the successful migration of combined water and the free water.In the middle stage,when the total amount of combined water reaches the maximum,the drying rate enters the descending stage,and the evaporation of water starts to decline.In later stage,the combined water predominates,the total water signal no longer changes,and the drying rate tends to be constant.The effects of ultrasonic pretreatment and freeze-drying on the energy consumption,microorganism and quality of barleygrass were studied.The results showed that the pretreatment of freeze-dried barley leaves shortened the total time by 7-21%and the energy consumption by 5-19%.The total decling colony was 33%,and the coliforms of E.coli were20MPN/g.The content of flavonoids and chlorophyll of barleygrass were higher than 9.00g/kg by ultrasonic pretreatment.Ultrasonic pretreatment of freeze-dried barley grass can better maintain the product color and improve product flavor,reduce the product moisture content and water activity,and can improve the glass transition temperature of product stability.The effects of high energy nano-ball grinder on grain size,nutrition and physicochemical properties of barley grass seedling were studied.Nanoscaled barley grass power（less than300nm）was obtained by collising of the samples with high-energy ZrO₂ ball under nitrogen protection,which solves the problems of large grain size.In addition,the problems of poor solubility are also resolved.The nutritional and physical properties of barley grass seedling with different grinding time were also studied.Accumulation density of powder increased with the processing time,and the content of nutrient component decreased slightly.Under the protection of nitrogen,chlorophyll and flavone content in the nano-barley powder were higher than that under no protection of nitrogenThe effects of radio frequency sterilization on the microorganism,quality,antioxidant substances and sensory quality of barley grass seedling powder were studied.Results showed that the microbial deactivation needed more energy consumption as the spacing between electrode gaps increased.To reduce 1-log microorganisms,the minimum energy required is350J/g.RF sterilization can better retain the nutrition and color of barley grass powder.In addition,RF sterilization can reduce moisture content,and affect the sour,bitter and tasty of product.It is proved that the RF sterilization is a good physical sterilization method,which avoids the unsafe problems caused by the radiation(⁶⁰Co)sterilizationIn this paper,effects of three drying methods on nutritional quality and microorganism in the storage period were studied.The results showed that different drying methods had different effects on the physicochemical properties of barley grass seedling powder during storage.The sensory quality of spray-dried barleygrass seedling was superior to microwave freeze-drying and microwave vacuum drying during the storage.Stability of chlorophyll flavone was improved by different drying methods.The effects of different drying methods on the color,density,particle size and antioxidant content during storage were different.The effect of three drying methods on the microorganism in the storage was weak.During the 18months of storage,it is still showed that microorganism in barleygrass powder was limited for good food safety...