Evaluation of Blueberry Fruit Processing Performance Based on Raw Materials and Juice Quality

The fruits of 12 blueberry varieties cultivated in the open field in southern Liaoning such as 'Bluegold', 'Reka', 'N5' were used as test materials. The best varieties for processing were selected through the analysis of fruit appearance, nutritional quality and processing performance indexes. The results showed that the blueberry fruit was mainly blue, flat spherical in varying degrees with bloom, and the single fruit weight was 0.95~2.63 g. The fruit contained more than 80% water, the larger the fruit the higher the water content, and the more flat. The fruit contained fructose, glucose, oxalic acid, quinic acid, malic acid, shikimic acid and citric acid. The content of fructose was equal to that of glucose, and the content of citric acid was significantly higher than that of other organic acids (P<0.05). It belonged to fructose accumulation type and citric acid dominant fruit. All tested fruits varieties contained potassium, magnesium, calcium, iron, manganese, zinc and copper, and their contents decreased successively. The potassium content was the highest (5786 mg∙kg⁻¹), which was extremely significantly higher than other elements (P<0.01). The potassium content (7400 mg∙kg⁻¹) in 'Darrow' fruit was the highest. The juice yield of different varieties of fruits without pectinase treatment was very different (the coefficient of variation was 60.42%), and the difference of juice yield of pectinase treatment was very small (the coefficient of variation was only 3.88%). The juice yield and the content of soluble sugar and titratable acid of fruit juice were significantly improved by pectinase treatment. Pectinase could improve the yield and quality of fruit juice. The higher the content of fructose and glucose in fruit, the higher the content of soluble sugar in fruit juice (correlation coefficients were 0.96 and 0.98). The higher the content of citric acid and quinic acid in fruit, the higher the content of titratable acid in fruit juice (correlation coefficients were 0.81 and 0.71). The soluble sugar (>90 mg∙g⁻¹), organic acid content (>10 mg∙g⁻¹) and juice yield (>74.6%) of 'Sunrise', 'Bluegold' and 'Patroit' were higher, which were better processed varieties. In conclusion, the fruits of 'Sunrise', 'Bluegold' and 'Patroit' were rich in nutrition and high juice yield. They were ideal raw materials for processing.