ABSTRACT

 Bracken fern (Pteridium aquilinum) is a very popular species of vegetable fern plant that grows abundantly in humid and wet seasons. This study was to evaluate the Drying Kinetics, Sorption isotherms and the optimization of drying temperature, drying time and weight on the Moisture Content, Total carotenoid, Vitamin C and Tannin contents of Bracken fern {Pteridium aquilinum). Sorption isotherms were obtained by gravimetric method. Page, Lewis and Logarithmic models were used at temperatures of 40°C, 50°C and 60°C. The chemical composition of bracken fern was 86.15% moisture content, l.’23% ash, 0.54% fat, 3.73% crude protein, 3.79% crude fibre, 4.58% carbohydrate, 49.00mg/kg carotenoid and 0.005mg/100g Vitamin C. The phytochemical composition of bracken fern was 0.43mg/kg Tannin, 0.24 mg/lOOg Oxalate, 0.68 g/kg Phytate, 0.88 % Flavonoid, 3.69% Saponin, 0.91% Alkaloid and 0.05mg/kg Hydrogen Cyanide. The mineral composition was 4.24mg/100g Calcium 0.16mg/100g Magnesium, 0.88mg/100g Potassium, 2.61mg/100g Iron and 3.00mg/100g Sodium. Page, Newton and Logarithmic models were used for drying kinetics and Logarithmic model gave the best result with a R2of 0.9585 at a temperature of 40°C. GAB and BET models were used for the sorption isotherm at a temperature of 40°C, 50°C and 60°C and BET was the most suitable model with a R2 of 0.9384 at 60°C. The isosteric heat of sorption of bracken fern decreased from 99,877 J/mol to 4,553 J/mol as water activity increased from 0.1 to 0.9. Optimization was done at drying temperature of 70 to 100°C, drying time of 40-60°C and weight of 5-15grams. Experimental design was based on Central composite design (CCD) and Design Expert software version 6.0.8. The data were analyzed statistically using analysis of variance (ANOVA) and regression analysis at p<0.05 significance level. The model developed was significant and has goodness of fit with an R2of 85.91%, 81.78%, 85.77% and 85.11% for moisture content, total carotenoid, vitamin C and tannin content respectively. Optimized process conditions for producing best bracken fern were temperature (minimum), time (in range) and weight (maximum) with an independent response of 54.50% Moisture Content, 22.60mg/Kg Total Carotenoid, 0.0048mg/100g Vitamin C and 0.1707mg/Kg Tannin having a desirability of 0.864. These conditions were considered to retain nutrients, more economical, time and energy saving