Abstract The simultaneous mass transfer of bioactive compounds, water loss and solids gain occurring during osmotic dehydration of apple wedges with beetroot juice was investigated. Beetroot juice was adjusted to 50°Bx with sucrose and further used as osmotic medium at 30, 40 and 50 °C. Impregnation of bioactive compounds was described in terms of total antioxidant capacity (TAC), total phenolic compounds (TPC) and total betalains (betacyanins and betaxanthins) contents. An unsteady state 3D-diffusion model, where product is shaped as a prolate spheroidal wedge, was proposed for describing experimental data and for obtaining equilibrium points and diffusion coefficients of migrating species with and without considering the apple shrinkage. The effect of geometry mismatch on the estimation of diffusion coefficients when product is shaped as spherical wedges is also explored. Results indicated that after 480 min apple cuts impregnated with beetroot juice increased their TPC in about 7–20 mg GAE/100 g from 43 ± 2 mg GAE/100 g in fresh product. On the other hand, TAC was increased in about 45–123 mg Trolox/100 g from 57 ± 0.8 mg Trolox/100 g in fresh product for the same processing time, being betalains the main responsible for this change. Shrinkage had a larger effect on the estimation of diffusion coefficients than geometry mismatch under the explored experimental conditions. Diffusion coefficients for bioactive compounds corrected for apple shrinkage were in the range of 0.49–6.05 × 10−11 m2/s. The use of higher impregnation temperatures caused a significant increase in equilibrium points of TPC and TAC (p

中文翻译：

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用甜菜根汁浸渍的苹果楔中生物活性化合物的传质分析：一种 3D 建模方法

摘要 研究了在用甜菜根汁对苹果楔形物进行渗透脱水过程中同时发生的生物活性化合物的传质、水分损失和固体增加。用蔗糖将甜菜根汁调至 50°Bx，并在 30、40 和 50°C 下进一步用作渗透介质。生物活性化合物的浸渍用总抗氧化能力 (TAC)、总酚类化合物 (TPC) 和总甜菜碱（甜菜红素和甜菜红素）含量来描述。提出了一种非稳态 3D 扩散模型，其中产品形状为长球体楔形，用于描述实验数据以及在考虑和不考虑苹果收缩的情况下获得迁移物种的平衡点和扩散系数。还探讨了当产品形状为球楔时几何不匹配对扩散系数估计的影响。结果表明，用甜菜根汁浸渍 480 分钟后，苹果切块的 TPC 从新鲜产品中的 43 ± 2 mg GAE/100 g 增加了约 7–20 mg GAE/100 g。另一方面，在相同的加工时间内，新鲜产品的 TAC 从 57 ± 0.8 mg Trolox/100 g 增加了约 45–123 mg Trolox/100 g，甜菜碱是造成这种变化的主要原因。在探索的实验条件下，收缩对扩散系数的估计比几何不匹配有更大的影响。修正苹果收缩后的生物活性化合物的扩散系数在 0.49–6.05 × 10-11 m2/s 的范围内。