Waste Cooking Oil as Substrate for Single Cell Protein Production by Yeast Yarrowia lipolytica

Abstract

Cooking oils are widely used in food preparation. During cooking, harmful compounds are formed in oils, therefore utilization of used cooking oils (waste cooking oils) is limited. Single cell protein (SCP) is dietary protein, which can be produced from various protein-rich microorganisms that are capable of utilizing industrial by-products such as waste cooking oil (WCO). In this study the utilization of industrial WCO (obtained from local potato chips manufacturer) as a carbon source for single cell protein production by yeast Yarrowia lipolytica was assessed. The medium containing 27.5 g/L WCO and C/N ratio of 5–10 for batch fermentations was determined to be the optimal composition for SCP production. In this study, the highest reported Yarrowia lipolytica biomass concentration (57.37 g/L) was achieved when WCO was used as the main carbon source. Protein concentrations were relatively low (12.6 %), which also affected the final protein yield (7.23 g/L). The resulting biomass accumulated low concentrations of toxic malondialdehyde (MDA) (2.32 mg MDA/kg) compared to concentrations initially detected in the WCO itself (30.87 mg MDA/kg). To the best of the authors knowledge this is the first study to report on MDA decrease via microbial fermentations.

Optimization of Yeast Cultivation Factors for Improved SCP Production

“…Arous et al [22] report that the optimal C:N ratio was 8:1-10:1 for S. etchellsii and C. pararugosa with higher biomass production on oil mill wastewater-based medium with ammonium chloride supplementation [22]. In the study by Spalvins et al [64], the highest SCP content in Y. lipolytica biomass was observed at 5:1-10:1 C:N ratio cultivated on waste cooking oil contained medium [64].…”

“…A number of agro-industrial waste and by-products have been used for the production of SCP and other metabolites, including glycerol [24], cheese whey [20], waste milk [21], different fruits peels [18], industrial waste cooking oil [64], salad oil manufacturing wastewater [30], potato processing wastewater [23], [65], olive mill wastewater [22], organic fraction of municipal solid waste [57]. Table 1 summarizes studies with the biomass and protein content using different substrates, cultivation conditions, and yeast species.…”

“…Another important factor in successful yeast cultivation is the choice of temperature and pH of medium. According to the literature, the most common temperature used for protein biosynthesis by yeast species is 25-30 °C [22], [24], [46], [64], [73]; however, for some yeasts, such C. utilis and K. marxianus a temperature of 35 and 40 °C can be used [58]. Low temperature can inhibit nutrients from crossing the cell membrane, while a high temperature may inactivate enzymes of the metabolic pathway [22].…”

Effect of Polysorbates on the Growth of Rhodotorula Glutinis in Oil Rich Medium

“…The lipids are usually degraded into free fatty acids by yeast extracellular lipases and incorporated into the cells by active transporters or by simple diffusion depending on the concentration difference [6]. As shown by our previous study [17], WCO is an effective substrate for the cultivation of Y. lipolytica with high biomass yield results, which can significantly reduce the cost of fermentation [17].…”

Production of Enriched Sporidiobolus sp. Yeast Biomass Cultivated on Mixed Coffee Hydrolyzate and Fat/Oil Waste Materials

“…The annual world production of waste frying oil is 0.9–1.5 million tons [ 10 , 12 ]. WFOs are standardly used in biogas plants for biogas production or for the production of biodiesel [ 13 , 14 ], but these products are also burned and, as a result, as in the case of SCG, they also increase the carbon load on the environment [ 15 , 16 ].…”