Lactic acid production using waste generated from sweet potato processing

Abstract

Summary Organic waste generated from industrial sweet potato canning is estimated to be 30% of incoming raw material with significant residual carbohydrate content. The purpose of this study was to evaluate the potential of waste generated from sweet potato processing material to support the growth of lactic acid bacteria and the production of lactic acid. The waste was comprised of 16.5% solids consisting of 18.5% ash, 4.4% protein, 20.5% simple sugars and 19% soluble starch. Following a screening of three lactic acid bacteria strains, Lactobacillus rhamnosus was deemed the best candidate for lactic acid production. The potential of various dilutions of the enzyme‐hydrolysed waste, with and without pH control, as a fermentation substrate was evaluated. Lactic acid production was highest in hydrolysed waste (without dilution) at pH set point 5.0, yielding 10 g L−1 in 72 h. Thus, lactic acid, a valuable organic compound, can be generated from sweet potato waste.

Potential use of byproducts from cultivation and processing of sweet potatoes

“…PAGANA et al (2014) were able to produce 10g of lactic acid per liter of sweet potato waste. This is 40% of the theoretical yield based on 30g of glucose available in the sweet potato waste media.…”

Processing, Valorization and Application of Bio-Waste Derived Compounds from Potato, Tomato, Olive and Cereals: A Review

“…Enriched potato wastes from potato flakes processing (without pretreatment) were also found to be a good nutrient source for the production of glucoamylase by several strains of Aspergillus niger [116]. Pagana, et al [117] produced lactic acid using different acid lactic bacteria and sweet potato wastes (peel and water with residual flesh) enriched with sugars. For this purpose, a previous enzyme hydrolysis of the waste was carried out.…”

Screening for Direct Production of Lactic Acid from Rice Starch Waste by Geobacillus stearothermophilus

“…Most of the lactic acid producing microorganisms require hydrolysis of starch containing carbon sources to glucose before the fermentation process represents an advantage of using this particular bacterium. The other characteristics of this bacterium are facultative anaerobic and gram-positive from the phylum Firmicutes, with an optimum growth temperature between 50°C and 60°C, while pH of 6.2 and 7.5 [2,3].…”