Blueberries belong to the Rhododendron family and are perennial deciduous or evergreen shrubs or small shrubs native to North America. The early settlers used it as daily food and medicine. In recent years, with the in-depth research on blueberry and people's attention to health, blueberry has gradually been regarded as a health care product and functional food. The pulp of blueberry is delicate, sweet and sour, extremely nutritious, and has the reputation of being "the king of berries". Blueberries are rich in sugar, amino acids, Vc, VE, VA, dietary fiber, and other nutrients, and potassium, iron, zinc, manganese, and other elements. In addition, it is also rich in essential amino acids, linolenic acid, and phenolic acid, as well as flavonoids such as chlorogenic acid, anthocyanin, and anthocyanin.
In the present study, seven blueberry varieties in the blueberry planting base were used as test materials, and they were dried by heat pump drying, and the quality characteristics of the samples before and after drying were determined, including soluble sugar content, Vc content, anthocyanin content and polyphenol content. ; Compared the differences between varieties after drying and the changes before and after drying, and determined the scavenging ability of anthocyanins to DPPH·free radicals after drying; based on these quality characteristics, a systematic cluster analysis was performed to select blueberry varieties suitable for drying, Then the blueberries of this variety were dried in three different ways, including heat pump drying, hot air drying and vacuum drying. The above quality characteristics were also measured and compared, and the three drying methods were briefly evaluated.
Dried fruits and vegetables is a processing method to remove the moisture in fruits and vegetables to prolong the preservation period of fruits and vegetables. There are various drying methods for fruits and vegetables, including hot air drying, heat pump drying, infrared drying, microwave drying, vacuum freeze drying, solar drying, fluidized bed drying, and combinations of the above drying methods. Fruit and vegetable drying technology has been widely used in the fruit and vegetable processing industry, but there are relatively few research reports on blueberry drying. Due to the high drying efficiency and energy saving of heat pump drying, its applications are relatively numerous.
The nutrient composition, rehydration ratio and anthocyanin species of 7 different varieties of blueberries after being dried by heat pump are very different. Based on these quality characteristics of dried blueberries, cluster analysis was carried out, and the 7 varieties of dried blueberries were divided into 3 categories. consider. The results show that vacuum drying can retain the nutritional and functional components of blueberries better. In summary, vacuum drying is better than heat pump drying and hot air drying, but it has a disadvantage, that is, the drying time is longer.