Fitting of the models
The pH and TTA of cassava mash obtained from the 19 runs during various fermentation conditions is presented in Table 2. The pH of the cassava mash ranged between 3.8 to 4.60 to a range of 3.80 (run 9) to 4.60 (run 3, 8, 13). The fresh cassava with pH 6.5 has been shown to have reduced; this indicated that fermentation reduced the pH of the cassava mash. This agrees with the report of [8] for gari production which reduced from 6.7 to 4.0; Oyewole and Ogundele [11] for fufuwhich reduced from 5.8 – 4.1; Oyewole and Ogundele [11] had reported that fermentation process was characterized by increased acid production. While the total titratable acidity (TTA) ranged from 0.09 (run 17, 18) to 0.22% (run 5) lactic acid. The TTA obtained were higher than those reported by Osundahunsi [2] for “pupuru” (0.09 – 0.12) and Awolu et al [12] for Abacha (0.047 to 0.073%) but within the range reported by [11] for fufu (0.08 – 0.22) % lactic acid. The activity of lactic acid bacteria on the carbohydrates of the cassava root has been attributed to the acid production during cassava fermentation [5]. This may be as a result of the several microbes and enzymes such as polygalacturonase, pectinase and cellulase with tissue degrading activities associative interaction of tissue softening produced [5]. The long fermentation time resulted in flavour addition to the product by the increase in total titratable Acidity (TTA) and decrease in pH level.