| dc.description.abstract | Lactic acid has a wide range in uses in the food, pharmaceutical and cosmetic industries, and can be used in the formation of Polylactic acid (PLA), a biodegradable plastic. Currently, there is rising interest in renewable lactic acid production from biomass. The aim was to develop an economically feasible ensiling process for lactic acid production, using Beta vulgaris as the chosen feedstock. To determine optimal ensiling conditions, the use of buffer treatments, nutrient additives, and incubation temperature and duration were investigated. Two optimal buffer treatments that were established: 7.5% w/v CaCO3 and 0.75% w/v Ca(OH)2 and 6% w/v Mg(OH)2 produced the highest lactic acid yields, with the lowest variability. Ensiling with addition of yeast extract and soybean meal significantly improved lactic acid production, with yeast extract increasing lactic acid titres by a maximum of 67.5%, and soybean meal increasing titres by a maximum of 63.3%. This shows the importance of a nutrient additive in this process to provide the lactic acid bacteria with a nitrogenous supplement. It was also discovered that the optimal buffer treatments had differing optimal ensiling temperatures and duration. The optimal ensiling temperature for 7.5% w/v CaCO3 was 45 °C and the optimal duration was 14 days. For the 0.75% w/v Ca(OH)2 and 6% w/v Mg(OH)2 treatment, the optimal ensiling temperature was 30 °C and the optimal duration was 8 days. Sugar beet ensiling at the optimal conditions, including a selected buffer treatment and nutrient addition results in high lactic acid titres of up to 159.4 g l-1 and a yield of 81.1% (maximum theoretical conversion of hexose sugars to lactic acid) and is therefore a successful ensiling process for lactic acid production. However, further work should be carried out to improve the cost-effectiveness of the process. | en_GB |
