Production of sweet potato distilled beverage: Economic evaluation via enzymatic and acid hydrolysis

Abstract This study aimed to assess the feasibility of utilizing sweet potato waste for distilled beverage production in two process scenarios: (i) acid hydrolysis and (ii) enzymatic hydrolysis. Laboratory experiments were conducted using in natura sweet potato waste and the data obtained were used to design a production system capable of producing 1000 L of distillate per day. Net present value (NPV), internal rate of return (IRR), and discounted payback indicators were used for economic analysis, with a minimum attractiveness rate (MARR) of 15%. The initial investment for the projects was BRL 1 139 610.86 (USD 223 146.80) for enzymatic hydrolysis and BRL 1 314 824.54 (USD 257 455.36) for acid hydrolysis. Packaging costs were identified as the greatest expenses in the process. Assuming a selling price of BRL 14.50 (USD 2.84), the enzymatic hydrolysis process demonstrated an NPV of BRL 4 792 520.77 (USD 938 421.92) and IRR of 83.39%, and the acid hydrolysis process showed an NPV of BRL 2 191 636.78 (USD 429 143.68) and IRR of 42.49%. Consequently, establishing a production plant for distilled beverages proved to be more economically attractive when employing the enzymatic hydrolysis process and fermentation simultaneously, resulting in a return on investment within 1.46 years of operation. Upon scrutinizing the gain matrix, it became apparent that critical factors with the potential to affect the project's feasibility detrimentally, if increased, included the cost of acquiring packaging, the final volumetric fraction of the distilled beverage, and the tax rate. Nevertheless, an upturn in the selling price of the beverage and a process improvement yield both have the potential to underpin the project effectively.