| Potatoes are the only tuber vegetables as the main food crop and have long played an important role in human diets.In order to broaden the scope of potato processing and promote the development of the potato industry,taking“Purple Rose”potato as the main raw stuff,the influence of hot-air drying,vacuum drying,and medium and short wave infrared drying on the physical and chemical properties,processing characteristics,and oxidation resistance of raw purple rose potato powder were investigated to obtain optimal drying method.Then,the effects of hot air drying at 45℃,50℃,55℃,60℃and 65℃on the relative properties of raw purple rose potato powder were studied and the most suitable drying temperature was selected.Secondly,the effects of different grinding time on the properties of the raw powder of purple rose potato were studied,and the appropriate grinding time was determined.Finally,three kinds of raw powders and three kinds of cooked powders were prepared from purple roses,red roses and yellow roses,and compared with commercial Atlantic potato flakes.The physicochemical properties measured include total phenols,anthocyanins,reducing sugar content,particle size.The processing characteristics studied include gelatinization degree,gelatinization properties,swelling properties,freeze-thaw stability,transparency and stability.Antioxidant properties include DPPH·,ABTS~+·and·OH scavenging capacity.The result is as follows:(1)When the drying temperature is 55℃,the content of total phenols and anthocyanins in hot-air-dried raw purple rose potato powder is higher than that in vacuum and medium and short-wave infrared drying.Its gelatinization degree,iodine blue value and reducing sugar content were the lowest,the color is better,and the anti-oxidation ability is stronger.(2)Hot air drying at 45℃to 65℃,the total phenols and anthocyanin contents of the raw purple rose potato powder dried at 55℃are the highest,and the gelatinization degree,iodine blue value and reducing sugar content are the lowest.The brightness was not significantly different from that obtained by drying at 45℃,50℃,60℃and 65℃.At the same time,the antioxidant power was superior to the other four temperatures.The raw purple rose potato powder dried at 55℃in hot air showed less nutrient loss and excellent processing performance.(3)Prolonging the grinding time is beneficial to the dissolution of total phenols and anthocyanins in the raw purple rose potato powder.However,it is not the longer the grinding time,the higher the extraction rate.The anthocyanin content reached a maximum of 81.77mg/100 g at 50 s.With the increase of grinding time,the particle size of the raw powder was reduced and the uniformity was improved,but the degree of gelatinization and iodine blue were increased,and the degree of cell damage was increased.The degree of gelatinization,iodine blue,and reducing sugar content were the lowest at the time of grinding for 30 s.At this time,the quality of the raw powder was the best,and the color was closest to the color of the purple rose potato,which was more conducive to the use of powder in traditional Chinese staple foods application.The DPPH·and ABTS~+·clearance rates of raw purple rose potato powder decreased with the increase of grinding time.The DPPH·and ABTS~+·scavenging capacity of the raw powder was the highest at 30 s,and the·OH scavenging capacity was highest at 60 s.(4)The content of total phenols and anthocyanins in the raw powder was significantly higher than that of cooked powder.Among the raw/cooked powders,the content of total phenols and anthocyanins in the powder made from purple rose potato was the highest.The content of reducing sugar in raw purple rose potato powder was higher than that in Atlantic snowflake powder,but was significantly lower than that of red rose,yellow rose potato raw powder and three kinds of cooked powder.The results showed that the functional components of raw purple rose potato powder were more comprehensive,and the color and processing quality were better.The gelatinization degree of the raw powders was significantly lower than that of the cooked powders and snowflake powders,and the purple rose potato powder had the lowest gelatinization degree in the raw/cooked powders.The raw powders are more difficult to be gelatinized than the cooked powders and snow flakes,and their shear resistance,hot paste stability,freeze-thaw stability,transparency and stability are better.The solubility of raw powders was significantly higher than that of the cooked powders and snow flakes,indicating that the raw powder had higher dissolving and dispersing ability.When the temperature is lower than 80℃,the swelling degree of cooked powder and Atlantic snowflake powder is obviously larger than that of raw powders,which indicates that the gelatinization degree of the cooked powder and snowflake powder is higher.The antioxidant power of raw purple rose potato powder is the best,indicating that raw purple rose potato powder can be used as a functional food for development and research.Therefore,the application of raw potato powder in food processing has broad prospects. |
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