Determine the effects of drying temperature on the quality change and antioxidant activity characteristics of blueberry

Abstract

This study was performed to investigate the effect of drying temperature on the quality characteristics and antioxidant activity of blueberry. Blueberries were dried at different times and temperatures, including A (40℃, 72 hr), B (40℃, 48 h and 50℃, 24 hr), C (50℃, 72 hr), and D (60℃, 72 hr). The yield and pH ranges of blueberry were determined to be 17.73~31.17% and 3.20~3.25, respectively. The yield rate of A treatments, soluble solid of D treatments, was the highest. The yield rate and soluble content was the highest in the treatment of A and D, respectively. The moisture content and water activity were significantly decreased with the increase in drying temperature (p<0.05). The L value of A treatment, and a and b values of D treatment were the greatest. In the analysis of texture analyzer, hardness, springiness, cohesiveness, gummiess and chewiness were significantly increased with the increase in drying temperature (p<0.05). In the sensory evaluation of blueberry, the appearance and color were the highest in the A treatment. The moisture, texture and taste was highest in the B treatment. The overall acceptability was in the order of B > A > C >D. The total polyphenol content and DPPH radical-scavenging activity were 9.21~13.05 mg/GAEg and 61.90~81.42%, respectively, which were significantly decreased with the increase in drying temperature (p<0.05). Therefore, the optimum time and temperature for blueberry drying was founded to be B treatment (40℃, 48 hr and 50℃, 24 hr) among other treatments.

Hyperspectral imaging technigue for monitoring moisture content of blueberry during the drying process

“…Those between MC and lightness, TPC, TFC, and TSS were 0.9 or more, and high correlations between hardness and strength (0.979) and TPC and TFC (0.977) were also determined. Lee et al (2011) reported that differences in TSS might be related to differences in MC during the drying process, and Shin et al (2015) observed that the difference in texture of dried blueberries was correlated with the difference in MC during the drying process, which is similar to the results of this study. Pearson's correlation coefficients can induce quality characteristics that indirectly affect the β coefficient.…”

“…In order to reduce the error of the experiment, only those in good condition and weighing 1.9±0.2 g were selected and used. Shin et al (2015) reported that the lower the drying temperature, the brighter and more purple the fruit, and the less the change in color; therefore, the blueberry in this study were dried at 35℃-40℃ using a climatic chamber (JSRH-150CP, JS Research Inc., Gongju-si, Korea). The blueberries were divided into five groups based on drying time (days): 0 (BB-0), 3 (BB-3), 6 (BB-6), 9 (BB-9) and 12 (BB-12).…”

“…Drying is widely used to overcome this issue (Park et al, 2014). Drying reduces the moisture content (MC) of food, which aids in preventing spoilage and degradation by microorganisms and enzymes, thereby contributing to improved shelf life and expanding the options of food product development (Shin et al, 2015).…”