ABSTRACT
Gluconic acid is a non-corrosive, non-toxic, biodegradable, weak organic acid. It mainly occurs in plants, fruits, wine, and honey. It is widely utilized in food, medicinal, textile, and cosmetic formulations. The aim of this research study is to optimize the production of gluconic acid from a ternary mix of feedstocks consisting of pineapple peels, watermelon peels, and orange pith. Fresh pineapple peels, watermelon peels, and orange pith were obtained from neighborhood markets close to the University of Benin, Nigeria. The fermentation experiments were planned using a three-variable D-Optimal mixture design. Potato dextrose agar was used as the agar medium to isolate the fermenting microorganism (Penicillium chrysogenum). This was prepared by dissolving 39g of the agar powder into 1,000 ml deionized water in a conical flask, and sterilizing for 15 min at 121OC. To determine the spore concentration of this solution, a haemocytometer was used to count a representative portion of it, and the number of spores counted was used to determine the total spore concentration of the solution. The feedstock weight formulated by the software were then used to fill 16 conical flasks to carry out the experiments. After 12days, analysis was carried out to determine gluconic acid concentration. After optimization, it was observed that 11.78g of pineapple peels and 3.22g of watermelon peels were needed to produce 42.80g/L of gluconic acid.
