Department of Chemistry, University of the Balearic Islands, Ctra. Valldemossa km. 7.5, 07122, Palma de Mallorca, Spain.
Food Funct. 2019 Jun 19;10(6):3209-3223. doi: 10.1039/c8fo02421a.
Drying may alter the microstructure of vegetables and influence the release of bioactive compounds during digestion. The effects of convective drying (at 60 °C and 2 m s-1; CD) and freeze-drying (at -50 °C and 30 Pa; FD) on the microstructure (evaluated using scanning electron microscopy (SEM) and image analyses with ImageJ software) of beetroot and the kinetics of biocompound release (total polyphenol content (TPC) and antioxidant activity (AA)) during 180 min of in vitro gastric digestion have been studied. Raw beetroot was used as the control. Drying promoted the collapse of cell walls causing volume shrinkage that resulted in a greater cell number per area unit; meanwhile in vitro digestion caused cell structure disruption, which resulted in a lower cell number per area unit. Drying promoted decreases of TPC (42% in CD and 29% in FD) and AA (66% in CD and 63% in FD) of beetroot. However, release of TPC and AA from dried samples during digestion was 82% (CD) and 76 (FD) % higher than from the raw sample. The Weibull model allowed the satisfactory modelling of the TPC and AA release kinetics (mean relative error of simulation lower than 8.5%).
干燥会改变蔬菜的微观结构，并影响消化过程中生物活性化合物的释放。本研究采用扫描电子显微镜（SEM）和 ImageJ 软件对图像分析，研究了在 60°C 和 2 m s-1（CD）的对流干燥和-50°C 和 30 Pa（FD）的冷冻干燥对甜菜根微观结构（评估）的影响，以及在 180 分钟体外胃消化过程中生物化合物释放的动力学（总多酚含量（TPC）和抗氧化活性（AA））。以生甜菜根为对照。干燥会导致细胞壁坍塌，造成体积收缩，从而使单位面积的细胞数量增加；而体外消化会导致细胞结构破坏，从而使单位面积的细胞数量减少。干燥会导致甜菜根的 TPC（CD 中减少 42%，FD 中减少 29%）和 AA（CD 中减少 66%，FD 中减少 63%）降低。然而，在消化过程中，干燥样品中 TPC 和 AA 的释放量比生样品高 82%（CD）和 76%（FD）。Weibull 模型能够很好地模拟 TPC 和 AA 释放动力学（模拟的平均相对误差低于 8.5%）。
