Study On Solid-state Fermented Potato Residue By Yeast And Lactobacillus Co-culture

With the rapid development of potato starch processing industry, the output of potato residue has increased. However, most of the potato residue has been abandoned without any effective utilization, which not only influced the sustainable development of potato starch industry, but also is waste of resources. In this article, the potato residue was fermented by co-culture of yeast and Lactobacillus to improve the content of crude and true protein of fermentation products.The nutrition value of potato residue was improved greatly. There were three trails in the experiment.The first trial was the choose of appropriate strains. The potato residue was used as raw material and fermented by six single and mixed strains (Saccharomyces cerevisiae, Candida tails, Geotrichum Candidum, Candida tropicalis, Lactobacillusplan-tarm, Lactobacillus acidophilus respectively). After the solid-state fermentation, the content of crude protein and true protein of the system were detected. The results showed that the content of crude and true protein of mixed strains fermentation were higher than those of single strain. Within the single strain, Geotr ichum candidum was the best one for potato reside solid-state fermentation, and the content of crude and true protein of fermented system were 31.3% and 12.15% respectively. The optimal strain combination was Saccharomyces cerevisiae+ Geotrichum Candidum+Candida tropicalis +Lactobacillusplan-tarm.The content of crude and true protein of mixed fermented system were 35.63% and 14.05% respectively.The second trail was the choose of appropriate fermentation medium. Based on the result of experiment one, single factor test and Orthogonal test test were designed to chose the optimal fermentation medium. In this experiment, usea, sulphate ammoninum, magnesium sulplate, potassium dibasic were studied to show the impact on crude and true protein of fermentation system.The rusult indicated that the suitable components of fermentation medium were potato residue 80%, wheat bran20%, Usea1.5%, sulphate ammoninum1.5%, magnesium sulplate0.06% and potassium dibasic0.4%. Under this condition, the content of crude and true protein of mixed fermented system were 36.52% and13.61% respectively.The third trail was the study of conditions of the fermentation. Based on the result of experiment one and experiment two, single factor test and perpndiculow test were designed to investigate the effects of temperature, time,inoculation ratio, inoculation amount and material loading on the fermentation. The crude and true protein as well as Amino acid content of fermentation system were detected. The results showed the best conditions were below: fermentation temperature was 32℃, fermentation time was 80h, inoculation ratio was 1:1:1:1, inoculation amount was 10%, material loading was 4cm. Under this condition, the content of crude and true protein of mixed fermented system were 36.96% and 14.28%. The content of crude protein and true protein were significantly increased compared to that before fermentation(P﹤0.05).