In the ethanol prduction process from cassava starch, two main steps are involved: Hydrolysis and Fermentation. Hydrolysis converts cassava starch to glucose using acids or enzymes. Fermentation produces ethanol from glucose by ethanologenic organisms. Both acid and enzymatic methods have their own merits and demerits.

First of all, I would like to focus on merits and demerits of acid hydrolysis. In terms of merits, acid hydrolysis produces higher yield of glucose if the process is pefoemed at optimized conditions of acid concentration, solid to liquid ratio, reaction temperature, reaction time and agitation speed. Cost of acid is cheaper than enzymes. Process conditions may not be harsh. In terms of demerits, degradation products of glucose form during hydrolysis. It happens sometime, which is beyond experimenter's control. In such case, glucose yield decreased. Also, to everyone's knowledge, stoichiometrically, at 100% recovery, only 1.11 gram of glucose can be produced per gram of starch.

Next, let's discuss about enzyme hydrolysis. In terms of advantages, enzymes are specific, versatile and produce enhanced yield at optimum conditions of pH, temperature, time, mixing, concentrations of substrate, enzyme and inhibitor. In terms of disadvantages, cost of enzymes are expensive than acids. A single enzyme is not sufficient to produce glucose from starch. A mixture of amylases and amyloglucosiodases (or glucoamylases) are required for hydrolysis. In enzymatic hydrolysis itself, three steps are involved: Gelatinization, liquefaction and hydrolysis. Again, experimenter should keep stoichiometry in mind.

Thank you for this question which openend up my mind to provide elaborate answer,

Thank you @sivamani

You are most welcome Moses Kayola Phiri