Pyrka Ioanna, Nenadis Nikolaos
Laboratory of Food Chemistry and Technology, School of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Natural Products Research Centre of Excellence-AUTH (NatPro-AUTH), Center for Interdisciplinary Research and Innovation (CIRI-AUTH), 57001 Thessaloniki, Greece.
Foods. 2025 Jun 10;14(12):2042. doi: 10.3390/foods14122042.
The present study examined the drying kinetics of two-phase olive pomace (OP) using near-infrared (NIR) thin layer intermittent drying at 70-140 °C. For the first time, this approach was combined with color, bioactive compound retention and antioxidant activity assessment. Among tested models, the Midilli's semi-empirical model best described the drying behavior ( ≥ 0.99839, RMSE ≤ 0.01349). Effective diffusivity ranged from 1.417 × 10 to 5.807 × 10 m/s, and activation energy was calculated at 23.732 kJ/mol. Drying at 140 °C reduced time by 68% compared to 70 °C. The corresponding sample had the highest total phenolics content, antioxidant activity (DPPH, CUPRAC assays) and triterpenic acid (maslinic, oleanolic) content, and a significant amount of hydroxytyrosol, despite the increased sample browning. Compared to oven-drying (140 °C), NIR was equal or better and 3.2-fold faster. The same was evidenced compared to freeze-drying, except for tyrosol recovery (1.2-fold lower in NIR). These findings were obtained using two different OP industrial samples. Given that NIR is already used industrially for food drying, the present study offers proof-of-concept for its application as a rapid and eco-friendly pretreatment of OP for food and feed uses. However, scalability challenges and the limitations of semi-empirical modeling must be addressed in the future to support industrial-scale implementation.
本研究考察了在70-140°C下使用近红外（NIR）薄层间歇干燥法对两相橄榄果渣（OP）的干燥动力学。首次将该方法与颜色、生物活性化合物保留率及抗氧化活性评估相结合。在所测试的模型中，Midilli半经验模型能最好地描述干燥行为（≥0.99839，均方根误差≤0.01349）。有效扩散率范围为1.417×10至5.807×10米²/秒，计算得出的活化能为23.732千焦/摩尔。与70°C相比，140°C干燥可使时间缩短68%。相应样品具有最高的总酚含量、抗氧化活性（DPPH、CUPRAC测定法）及三萜酸（山楂酸、齐墩果酸）含量，尽管样品褐变增加，但仍含有大量羟基酪醇。与烘箱干燥（140°C）相比，近红外干燥效果相当或更好，且速度快3.2倍。与冷冻干燥相比也有同样的结果，除了酪醇回收率（近红外干燥低1.2倍）。这些发现是使用两种不同的OP工业样品获得的。鉴于近红外已在工业上用于食品干燥，本研究为其作为OP用于食品和饲料的快速且环保的预处理方法提供了概念验证。然而，未来必须解决可扩展性挑战和半经验建模的局限性，以支持工业规模的实施。
