Model development and optimization of process conditions for color properties of tomato in a hot‐air convective dryer using box–behnken design

his study was conducted to improve on the retention of color properties of dried tomato fruits. Process conditions were optimized using response surface methodology (RSM). A three-level-four-variable Box–Behnken design was used for the optimization which involved 68 samples in triplicate, the variables were drying-air temperature, slice thickness, cultivar, and pre-drying treatment. The results indicated that quadratic models best described the behavior of color properties of tomato in hot-air convective dryer with R2 of 0.8080 and 0.7955 for hue angle color value (HACV) and color difference (CD), respectively. The process conditions significantly influenced the HACV and CD of dried tomato fruits. Through the RSM, the optimal process conditions for HACV and CD were as follows: drying-air temperature 50°C, slice thickness 5.11 mm, cultivar 1.75 (Tiwantiwa), and pre-drying treatment of honey and sugar solution with a desirability value of 0.838. HACV and CD obtained under these conditions were 39.55° and 33.64, respectively. Practical applications Tomato is one of the most important fruits and vegetables, and natural sources of lycopene and vitamin C. Drying is an important process used in the preservation of the fruit toward wastages minimization and also involved in the production of antioxidant food supplements. Color is a major criterion consumers usually consider to either accept or reject processed vegetables in the market. Through optimization of the process conditions involved in drying, the retention of color properties and overall quality were improved. This research showed great potential as related to selection of cultivar and development of new natural resources to be used as pre-drying treatment