The Influence Of Thermosonication On The Color Of Dendrobium Officinale Beverage And The Study On Its Stability

Dendrobium officinale Kimura et Migo,a traditional and precious Chinese medicinal herb,has been approved for processing and use in food industry.Dendrobium officinale beverage prepared using Dendrobium officinale as raw material helps to expand the scope of consumers and is beneficial to the development of the Dendrobium officinale industry.This study explored the quality changes occurred during the processing of Dendrobium officinale beverage,including the phenomena of sedimentation and stratification,color and quality deterioration during sterilization process of beverages,to develop a high-quality Dendrobium officinale beverage with good stability and low color deterioration.（1）The effect of thermosonication on the color deterioration and bactericidal effect of Dendrobium officinale beverage was explored.The results indicated that temperature is the main parameter affecting the color of Dendrobium officinale beverage during the thermosonication,which is mainly caused by chlorophyll degradation.Under these conditions:ultrasonic power,640 W;temperature,50℃;time,25 min;the microbial residue of Dendrobium officinale beverage can meet the requirements of national standards for beverage,which can be used as a parameter for thermosonication sterilization.Compared with pasteurization,using thermosonication sterilization,the sterilization effect is similar,the preservation rate of chlorophyll is increased and the color deterioration is decreased.（2）Based on the characteristics of thermosonication sterilization,the influence of high temperature sterilization and thermosonication sterilization on the quality of Dendrobium officinale beverage was compared.The results showed that thermosonication sterilization can effectively preserve the original color and bioactive components of Dendrobium officinale beverage.High temperature sterilization can easily lead to color deterioration and the loss of bioactive components,but its sterilization effect is stronger.Thermosonication sterilization has little effect on the original flavor of Dendrobium officinale beverages,while high temperature sterilization can give Dendrobium officinale beverages a richer aroma.（3）Metal ions as nutritional enhancers were added into beverages to reduce the color deterioration and strength the effect of preserving-green of Dendrobium officinale beverage during high temperature sterilization.The results indicated that Zn²⁺showed the best effect of preserving-green.Because Zn²⁺can combine with pheophytin,a high temperature degradation product of chlorophyll,to form Zn-pheophytin which promotes the green regeneration of the beverage.When the addition of Zn²⁺is 15 mg/kg,which meets the requirements for adding Zn²⁺as a nutritional enhancer in the beverage,the a^*value of Dendrobium officinale beverage with high temperature sterilization is similar to that of the beverage without sterilization.After being stored for 6 months,the a^*value of Dendrobium officinale beverage with Zn²⁺addition is still significantly lower than that of the beverage without Zn²⁺addition.（4）The preparation process of Dendrobium officinale beverage was improved to prepare a kind of Dendrobium officinale beverage with high raw material utilization rate and without sedimentation and stratification.In addition,the storage life of Dendrobium officinale beverage after thermosonication sterilization and high temperature sterilization was also determined.The results showed that processing parameters are listed as follows:the optimum parameters for the pulping process:pulping water ratio,1:20（g/g）;pulping time,20 min;the best addition amount of mogroside,0.15 g/L;the optimal addition amount of thickener:xanthan gum,0.3 g/L;sodium alginate,0.9 g/L;carrageenan,0.4 g/L;the homogenization process parameters:homogenization pressure,20 MPa;homogenization times,2.Under the optimum processing parameters,the Dendrobium officinale beverage is processed using thermosonication sterilization and high temperature sterilization treatments,respectively.The storage life of Dendrobium officinale beverage with thermosonication sterilization is about 20～24 d at 4℃,and 6～8 d at 25℃,and the Dendrobium officinale beverage is relatively stable and its color changes insignificantly.The physicochemical indexes and sensory difference of Dendrobium officinale beverage were measured at three storage temperatures using accelerated shelf life testing.According to the shelf life prediction model,the shelf life of Dendrobium officinale beverage is approximately 217 d at 25℃.