Nowak Dorota, Jakubczyk Ewa
Department of Food Engineering and Process Management, Institute of Food Sciences, Warsaw University of Life Sciences-SGGW, Nowoursynowska 159C, 02-776 Warsaw, Poland.
Foods. 2022 Aug 11;11(16):2407. doi: 10.3390/foods11162407.
The aim of this study was to investigate the effect of application of pulsed electric field (PEF) and different freezing methods (fast, slow and vacuum freezing) on the drying kinetics as well as selected physical properties of freeze-dried apple. The apples were subjected to PEF treatment with range of pulses from 0 to 160 and the intake energy from 0 to 1327 kJ·g. Apples with and without PEF treatment were frozen with different rates and the freeze-dried. The water content, water activity and colour attributes of freeze-dried apples were investigated. Regression analysis and fitting procedures showed that among six different models, the Midilli et al. model the best described the drying curves of all dried samples. The highest value of the parameter = 71.54 was obtained for freeze-dried sample prepared without PEF pre-treatment and fast frozen. Application of PEF pre-treatment resulted in increase in browning index of freeze-dried apples (). The studies confirmed the positive effect of PEF on the freeze drying rate only in the case of the slow or fast freezing of the material after the application of low-energy PEF treatment. However, the increase in drying rate was also observed after application of slow and vacuum freezing of the material without PEF pre-treatment. These technologies can be recommended for optimization of the freeze drying process of apples. The statement that the freeze drying process with application of appropriately selected PEF processing parameters causing only partial destruction of cell membranes can be considered as an innovative contribution to the development of science about the possibilities of PEF application.
本研究的目的是探讨脉冲电场（PEF）的应用以及不同冷冻方法（快速、慢速和真空冷冻）对冻干苹果干燥动力学以及选定物理性质的影响。对苹果进行脉冲电场处理，脉冲范围为0至160，输入能量为0至1327 kJ·g。对经过和未经过脉冲电场处理的苹果以不同速率进行冷冻，然后进行冻干。研究了冻干苹果的水分含量、水分活度和颜色属性。回归分析和拟合程序表明，在六种不同模型中，Midilli等人的模型最能描述所有干燥样品的干燥曲线。对于未经脉冲电场预处理且快速冷冻制备的冻干样品，参数的最高值为71.54。脉冲电场预处理导致冻干苹果的褐变指数增加（）。研究证实，仅在低能量脉冲电场处理后对材料进行慢速或快速冷冻的情况下，脉冲电场对冷冻干燥速率有积极影响。然而，在对未经脉冲电场预处理的材料进行慢速和真空冷冻后，也观察到干燥速率有所提高。这些技术可推荐用于优化苹果的冷冻干燥过程。关于应用适当选择的脉冲电场处理参数进行冷冻干燥过程仅导致细胞膜部分破坏的说法，可被视为对脉冲电场应用可能性科学发展的创新性贡献。
