| Seabuckthorn is rich in a variety of biological components and has high nutritional value.However,it has a high water content and short shelf life,which limits the development of seabuckthorn-related products.Drying is the most important processing method to prolong the shelf life of products.At present,the conventional drying strategies for seabuckthorn include hot air drying,microwave drying,freeze drying,and infrared drying.Of which,vacuum freeze drying is the most commonly used drying method,but it takes a long time and consumes high energy.In this research,ultrasonic pretreatment,ultra-high pressure pretreatment,and ultrasonic combined with ultra-high pressure pretreatments were used to assess the effects of ultrasonic pretreatment,ultra-high pressure pretreatment,and ultrasonic combined with ultra-high pressure pretreatment on the drying time and nutritional quality of seabuckthorn jelly dried powder.Based on the assessment the optimal method to prepare seabuckthorn fruit powder was established and the quality of the power was compared with the commercially available fruit powder.We hope that the current study can provide valuable information for the future practical processing of fruit powder products.(1)Effects of different ultrasonic and ultra-high pressure treatment conditions on the quality of freeze-dried powder of seabuckthorn.Seabuckthorn was pretreated with different ultrasonic(US)time(10,20,30,40,50 min)and different ultra-high pressure pressure and time,and the best treatment conditions were selected by water content,total phenols,total flavonoids,ABTS~+and DPPH.Finally,it was found that ultrasonic treatment of 30 min and ultra-high pressure 200 MPa-10 min,could effectively reduce the water content,shorten the freeze-drying time,and had a good level in the determination of total flavonoids and antioxidant capacity.(2)Effect of combined pretreatment on drying and nutritional characteristics of freeze-dried powder of seabuckthorn.US,UHP and ultra-high pressure combined ultrasound(UHP-US)treatment were selected to explore the advantages and disadvantages of different treatments.According to the drying kinetic analysis of freeze-drying process,pretreatment can increase the freeze-drying rate of seabuckthorn about 16%,reduce the freeze-drying time,and increase the effective diffusion coefficient of water;the fitting effect of,Two term model for freeze-drying process is the best;the color index of pretreated seabuckthorn jelly-dried powder is better than that of untreated group;in the determination of Vc content,the Vc content of ultrasonic treatment is the highest.The content of total phenols in UHP group was the highest,and the content of total flavonoids and antioxidant capacity in US-UHP group were the highest.According to the comprehensive evaluation,the drying speed of the combined pretreatment group was the fastest,and the whole jelly dried powder of seabuckthorn had better appearance,color and quality characteristics.(3)Quality evaluation of different Brands ofseabuckthorn fruit powderThrough the comparison of physical index,nutritional index and functional characteristics of fruit powder made by different brands and optimized technology,the physical index of seedless peel brand fruit powder was the best.the pretreated fruit powder was significantly higher than other groups in the determination of protein,anthocyanin,total flavonoids and antioxidant capacity.In the determination of hypoglycemic activity,the inhibition rate ofα-glucosidase in the pretreatment group was higher than that in other groups,but the difference was not significant.Generally speaking,the freeze-dried fruit powder of seedless skin brand has better appearance quality and solubility,but its nutritional characteristics are lower.The jelly dried powder of seabuckthorn after pretreatment has better physical properties and nutritional quality. |
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