Stamenković Zoran, Pavkov Ivan, Radojčin Milivoj, Tepić Horecki Aleksandra, Kešelj Krstan, Bursać Kovačević Danijela, Putnik Predrag
Faculty of Agriculture, University of Novi Sad, Trg Dositeja Obradovića 8, 21000 Novi Sad, Serbia.
Faculty of Technology, University of Novi Sad, Bulevarcara Lazara 1, 21000 Novi Sad, Serbia.
Foods. 2019 Jul 11;8(7):251. doi: 10.3390/foods8070251.
Raspberries are one of Serbia's best-known and most widely exported fruits. Due to market fluctuation, producers are looking for ways to preserve this fresh product. Drying is a widely accepted method for preserving berries, as is the case with freeze-drying. Hence, the aim was to evaluate convective drying as an alternative to freeze-drying due to better accessibility, simplicity, and cost-effectiveness of Polana raspberries and compare it to a freeze-drying. Three factors were in experimental design: air temperature (60, 70, and 80 °C), air velocity (0,5 and 1,5 m · s), and state of a product (fresh and frozen). Success of drying was evaluated with several quality criteria: shrinkage (change of volume), color change, shape, content of L-ascorbic acid, total phenolic content, flavonoid content, anthocyanin content, and antioxidant activity. A considerable influence of convective drying on color changes was not observed, as ΔE was low for all samples. It was obvious that fresh raspberries had less physical changes than frozen ones. On average, convective drying reduced L-ascorbic acid content by 80.00-99.99%, but less than 60% for other biologically active compounds as compared to fresh raspberries. Convective dried Polana raspberry may be considered as a viable replacement for freeze-dried raspberries.
树莓是塞尔维亚最知名且出口最广泛的水果之一。由于市场波动，生产商正在寻找保存这种新鲜产品的方法。干燥是一种广泛接受的浆果保存方法，冷冻干燥也是如此。因此，由于波兰那树莓具有更好的可及性、简易性和成本效益，本研究旨在评估对流干燥作为冷冻干燥替代方法的可行性，并将其与冷冻干燥进行比较。实验设计中有三个因素：空气温度（60、70和80°C）、空气流速（0.5和1.5 m·s）以及产品状态（新鲜和冷冻）。通过几个质量标准来评估干燥的成功与否：收缩率（体积变化）、颜色变化、形状、L-抗坏血酸含量、总酚含量、类黄酮含量、花青素含量和抗氧化活性。未观察到对流干燥对颜色变化有显著影响，因为所有样品的ΔE值都很低。很明显，新鲜树莓的物理变化比冷冻树莓少。平均而言，对流干燥使L-抗坏血酸含量降低了80.00 - 99.99%，但与新鲜树莓相比，其他生物活性化合物的含量降低不到60%。对流干燥的波兰那树莓可被视为冷冻干燥树莓的可行替代品。
