| Up to now, the industrial synthesis of polylactic acid (PLA) in North America relies essentially on the production of corn, which is a renewable resource. However, problems such as over exploitation of fertile soils, the increase of cereal price and the abusive use of chemical fertilizers, have been raised for this crop production, especially for its non-food utilization. Agri-food wastes show a promising alternative with their rich carbohydrate content, relatively stable composition and availability. Therefore, they represent an appealing waste valorization target for an eventual PLA production. Potato wastewater is one of these. During the slicing process in potato transformation, water is used to remove the excess of starch. Starch can be recovered from water after proper centrifugations.;A comparative cradle-to-gate life cycle assessment (LCA) was carried out to evaluate the potential environmental benefits of producing lactic acid for polylactide usage by directly fermenting potato waste starch, recuperated from the wastewater of a potato chip facility, with L. amylophilus. This environmental assessment was carried out by comparing its environmental impacts to the conventional process of lactic acid fermentation of dextrose from corn. Laboratory-scale experiments were performed and have proven the microbial feasibility of producing lactic acid with L. amylophilus and this agribusiness residue. To do so, lactic acid concentrations obtained from synthetic media fermentations supplied with glucose, commercial potato starch or potato waste starch were compared. The LCA results have demonstrated that polylactide produced from potato waste starch could have, with proper energy and nutrient concentration optimization, at least more or less the same impact in most end-point categories studied. This LCA has underlined that steam utilization is a major contributor process in climate change and resource depletion impacts and that a fermentation which leads to a more diluted final lactic acid concentration require more energy utilization improvements. The lack of publications about L. amylophilus and the inaccessibility to industrial data proved to be challenges in this project.;NatureWorks LLC has the only large-scale commercial production facility of PLA and is totally owned by Cargill. Lactic acid is presently produced by Cargill with the fermentation of dextrose (D-glucose), from the hydrolysis of corn starch. The use of an amylolytic lactic acid micro-organism could allow the direct fermentation of starch, reducing the processing steps for lactic acid synthesis. Lactobacillus amylophilus, which has homofermentative, amylolytic and non-pathogenic characteristics, could be an interesting micro-organism for L-lactic acid production. |
