Response surface methodology assessment of osmotic pre-drying and convective dehydration processes on the anti-oxidant property of Hausa variety of tomato

This study was conducted to determine the effect of osmotic pre-drying treatment on the vitamin C content of Hausa variety of tomato. The tomatoes used were sliced to a uniform diameter of 10 mm, deseeded and then osmotically pre-treated with sugar and honey solution at different osmotic concentrations (20, 30, 40, 50, 60 °Bx), osmotic time (10, 20, 30, 40 and 50 min) and osmotic temperature (10, 20, 30, 40, 50 °C). Experimental design was done using the Central Composite Design (CCD) methodology of Design Expert software version 6.0.6. Drying of the samples was done at 65 °C in a cabinet dryer operating mainly on convectional heat transfer. Drying process was completed and terminated when the samples reached their equilibrium moisture content between 3-5% after total drying time of 10 hours. The data obtained were analysed statistically using analysis of variance (ANOVA) and regression analysis at p≤0.05 significance level. The developed model was significant and has goodness of fit with an R2 value of 71.29% and lack of fit test was insignificant at p≤ 0.05. Optimized process conditions for producing the best quality of tomato product with vitamin C content of 22 mg/100 g were 35.43 °Bx osmotic concentration, 11.10 min osmotic time and 23.86 °C osmotic temperature having a desirability function of 1. These conditions were considered to be advantageous as they were more economical, time and energy saving

Effective Moisture Diffusivity and Rehydration Characteristics of Osmo-air Dehydrated Tomato

The aim of this study was to investigate the effect of osmotic dehydration on effective moisture diffusivity and rehydration characteristics of osmo-air dehydrated tomato. Sliced tomato samples of Hausa variety of uniform 10 mm thickness were deseeded, blanched at 90oC and immersed in an honey and sugar hypertonic solution under different levels of osmotic concentrations of 20, 30, 40, 50 and 60oBx, temperature of 10, 20, 30, 40 and 50oC and duration of 10, 20, 30, 40, and 50 min. Samples were dried in a hot-air cabinet dryer at 65oC for 10 hours to reach an equilibrium moisture content of 3-5%, which is considered safe for long term storage. The experiment was designed using central composite design (CCD) of response surface methodology (RSM) of Design expert software version 6.0.6. Statistical analysis and regression models were done using the software at p≤0.05 significance level. Results showed that effective moisture diffusivity (EMD) and rehydration ratio (RR) of Hausa variety of tomato for all samples were between 1.40 x 10-9 to 4.19 x 10-8 m2/s and 0.60 – 2.00 respectively. The maximum values EMD and RR of 3.42 x 10-8 m2/s and 1.81 were achieved at osmotic concentration of 20oBx, osmotic duration of 42 mins and osmotic temperature of 50oC respectively, through optimization with  desirability of 83.6%. This would aid faster drying rate thereby preserving more of foods quality parameters, reducing energy consumption and saving time.

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

Development of a Gasoline Food-Grade Magnetic Hammer Mill and Estimation of Milling and Energy Consumption Pattern of Some Selected Food Materials

This study was aimed to develop a laboratory-scale gasoline food-grade magnetic hammer mill and to estimate the milling efficiency, milling yield, milling time, energy consumption and energy intensity of some selected food materials (soybean, rice and cassava flakes). The hopper, shaft, sieve and hammers of the gasoline food-grade magnetic hammer mill are made of stainless steel and the structural base is made of mild steel. The cost of developing the gasoline food-grade magnetic hammer mill was ₦ 149,000. Cassava flakes were observed to have the highest milling yield (940 g), lowest energy consumption (0.94 MJ), energy intensity (0.94 MJ/kg) and the highest milling efficiency (94 %) while soybean was observed to have the longest milling time (5.86 mins). The developed gasoline food-grade magnetic hammer mill could be adopted for milling different food materials but its performance varies based on the food material

Optimization of process conditions for moisture ratio and effective moisture diffusivity of tomato during convective hot‐air drying using response surface methodology

This study was carried out to understand the moisture transfer behavior of tomato fruits subjected to pre-drying and drying processes. Effects of variety and process conditions on the moisture ratio (MR) and effective moisture diffusivity (Deff) of tomato were investigated using three-level-four-variable Box–Behnken design of response surface methodology (RSM). The experiment involved three varieties of tomato (Hausa, Tiwantiwa, and Roma VFN) and the process conditions include slice thickness (5, 7.5, and 10 mm), pre-drying treatment (ethyl acetate, NaCl, MgCl2∙6H2O and Na2S2O5, and honey and sugar solutions), and inlet air temperature (45, 55, and 65 °C). Results show that variety and process conditions influenced MR and Deff of tomato (p ≤ .05). Furthermore, quadratic model best described the moisture transfer behavior of tomato in convective hot-air dryer with R2 values of 0.8538 and 0.7150 for MR and Deff, respectively. Based on the aforementioned process conditions, optimum conditions achieved were Tiwantiwa variety, 5 mm slice thickness, pre-drying treatment in ethyl acetate solution, and inlet air temperature of 65 °C. With predictions of 0.774 and 2.844 × 10–8 m2/s for MR and Deff, respectively, and obtained desirability function of 0.771