IMAGE ANALYSIS AND DYNAMIC MODELING OF THIN-LAYER DRYING OF OSMOTICALLY DEHYDRATED PUMPKIN

• Published in: Journal of food processing and preservation Vol. 32; no. 1; pp. 88 - 102
• Main Authors: ZENOOZIAN, M. SHAFAFI, FENG, H, RAZAVI, S.M.A, SHAHIDI, F, POURREZA, H.R
• Format: Journal Article
• Language: English
• Published: Malden, USA Malden, USA : Blackwell Publishing Inc 01-02-2008; Blackwell Publishing Inc; Blackwell Publishing
• Subjects: Biological and medical sciences; Food engineering; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General aspects; Image analysis; Vegetables; Modeling; Pumpkin; Drying
• ISSN: 0145-8892; 1745-4549
• DOI: 10.1111/j.1745-4549.2007.00167.x

This study was conducted to investigate the effect of osmotic dehydration as a pretreatment on hot-air drying kinetics of pumpkin, to evaluate the best model for hot-air drying of pumpkin and to apply a computer vision system to study the color changes during drying. Pumpkin cubes were treated in 50% w/w sorbitol or sucrose solutions at 50C for up to 6 h, followed by hot-air drying at 60C and air velocity of 1 m/s. Drying data were fitted to 11 drying kinetic models. The goodness of fit was determined using the coefficient of determination (R²), reduced chi square (χ²), root mean square error (RMSE) and percent mean relative deviation modulus (E%). Hot-air dried samples pretreated with sorbitol had an improved lightness (higher L* values) compared to the hot-air drying while that pretreated with sucrose exhibited lower L* values. The total color changes (ΔE* values) increased during drying in a sequence ofΔE*sucrose solution < ΔE*sorbitol solution < ΔE*sucrose₊hot air & < ΔE*sorbitol₊hot air. The combined treatment of pumpkins using osmotic dehydration followed by hot-air drying may provide a practical method for the preservation of pumpkin and the production of dehydrated pumpkin products.