Solar Tunnel Drying: Pretreatment on drying kinetic of plum tomatoes

• Published in: Ciência rural 2019, Vol.49 (7)
• Main Authors: Karaaslan, Sevil, Ekinci, Kamil, Kumbul, Barbaros Salih
• Format: Article
• Language: English
• Subjects: AGRONOMY; Air temperature; Alternative energy sources; Color; Drying; Drying characteristics; Ecological conditions; Food preservation; Humidity; Irradiation; mathematical modeling; Mathematical models; Moisture content; Pretreatment; Radiation; Regression analysis; Relative humidity; Sodium chloride; Solar energy; Statistical analysis; tomato slices; Tomatoes; Tunnel driers; tunnel dryer; Vegetables; Washers & dryers
• ISSN: 0103-8478; 1678-4596; 1678-4596
• DOI: 10.1590/0103-8478cr20180988

Drying of thin layer tomato was studied using a solar tunnel dryer under the ecological conditions of Isparta, Turkey. During drying process, solar irradiation, drying air temperature, relative humidity, and air velocity were measured constantly in different parts of the dryer. Drying runs were performed using plum tomatoes, characterized by an oval shape, intense red color. The change of tomatoes mass was measured daily. The color measurements of dried products were determined at the beginning and end of experiment. In this study, the fresh tomato samples were sorted, graded, washed in water and then sliced into quarters and halves before pretreated. Sun drying behavior of half and quarter sliced tomatoes pretreated with 10% NaCl solution and non-pretreated was investigated. Results showed that the drying time for pretreated and non-pretreated samples was not significantly different. However, drying time and drying rates were affected by number of tomato slices (quarter and half). Drying characteristic curves were evaluated against thirteen mathematical models and the Midilli et al model was the best descriptive model for solar tunnel drying of thin layer tomato. Color analysis emphasized that if tomatoes are pretreated with 10% NaCl solution, they should be sliced in quarter for better quality. RESUMO: A secagem do tomate de camada fina foi estudada usando um secador de túnel solar sob as condições ecológicas de Isparta, na Turquia. Durante o processo de secagem, a irradiação solar, a temperatura do ar de secagem, a umidade relativa e a velocidade do ar foram medidas constantemente em diferentes partes do secador. As operações de secagem foram realizadas com tomates ameixa, caracterizados por uma forma oval, cor vermelha intensa. A mudança de massa de tomates foi medida diariamente. As medidas de cor dos produtos secos foram determinadas no início e no final da experiência. Neste estudo, as amostras de tomate fresco foram classificadas, lavadas em água e depois cortadas em quartos e metades antes do pré-tratamento. O comportamento de secagem ao sol do tomate em fatias de meio e quarto pré-tratadas com solução de NaCl a 10% e sem pré-tratamento foi investigado. Os resultados mostraram que o tempo de secagem para amostras pré-tratadas e não pré-tratadas não foram significativamente diferentes. No entanto, o tempo de secagem e as taxas de secagem foram afetadas pelo número de fatias de tomate (trimestre e meio). As curvas características de secagem foram av