真空冷冻-热风联合干燥对草莓品质的影响

Effects of Vacuum Freezing Combined with Hot Air Drying on the Quality of Strawberry

摘要:

以草莓为原料，研究真空冷冻干燥与不同时间、温度热风联合干燥对其品质的影响。从干燥后草莓的色泽、花色苷、硬度、气味、挥发性物质、水分流动性等指标比较热风干燥阶段中热风温度和时间对草莓的品质的影响。结果表明：真空冷冻干燥结合60 ℃ 2.5 h、70 ℃ 2 h、80 ℃ 1.5 h热风干燥条件下，能较好的维持草莓的色泽，减少花色苷的损失，且硬度适中。结合电子鼻和GC-MS对挥发性风味物质的分析，真空冷冻干燥结合80 ℃ 1.5 h热风干燥条件下，草莓中的挥发性物质保存的较好。通过低场核磁测定发现，真空冷冻与80 ℃ 1.5 h热风联合干燥，水分流动性较弱，与冻干样品接近，草莓结构保留较好。因此，真空冷冻干燥结合80 ℃ 1.5 h热风干燥在保持草莓色泽及其营养品质、挥发性成分等方面均有较好的优势。

Abstract:

The effects of vacuum freezing combined with hotair drying at different time and temperature on the quality of strawberry were investigated in this study, and the effects of the temperature and time of hot air on the quality of strawberry were compared with those of dried strawberry, such as color, anthocyanins, hardness, odor, volatile matter and moisture fluidity. Results showed that vacuum freezing combined with hot air drying (60 oC for 2.5 h, 70 oC for 2 h or 80 oC for 1.5 h) could better maintain the color of strawberry and reduce the loss of anthocyanin, and the hardness was moderate. According to the analysis of volatile flavor compounds by electronic nose and GC-MS, the volatile substances in strawberry were better preserved by vacuum freezing combined with hot air drying at 80 oC for 1.5 h. In addition, the results of low field nuclear magnetic resonance showed that the vacuum freezing combined with hot air drying at 80 oC for 1.5 h resulted in weaker moisture fluidity, which was similar to that of the lyophilized samples, and the structure of strawberry was well preserved. Consequently, vacuum freezing combined with hot air drying at 80 oC for 1.5 h had better advantages in maintaining the color, nutrition quality and volatile components of strawberry.