Study On Ethanol Production By Microbial Fermentation Of Potato Pulp

Potato pulp is a by-product of potato starch industry, main containing cellulose, hemicellulose, starch, pectin and a few proteins. It is difficult to keep storage and transportion due to to the pulp’s easy deterioration with stench. With the view of avoiding the resource wastes and and environmental pollution, the comprehensive utilization of potato pulp becomes the focus that the government and the potato starch industry pay attention to gradually. Bioconversion of potato pulp to fuel ethanol not only reduces the limited grain feedstocks, but also has important economic and social benefits in new energy development and environment protection. The main research subjects and results are listed as follows:1. The study was performed to evaluate the effect of washing treatment on the hydrolysis of potato pulp. The results showed there are no much different between the main component content of the washed potato pulp and the unwashed, but the enzymolysis liquid from washed potato has the content of reducing sugar and glucose0.42times and0.9times higher comparing with the unwashed one respectively.2. Comparing three different thermal pretreatments (microwave, ultrasonic wave, high-temperature cooking) effect on the enzyme hydrolysis of potato pulp. The results showed that three thermal pretreatment methods can effectively improve the potato pulp’s enzyme hydrolysis effect, microwave rank first and followed by high-temperature cooking and ultrasonic treatment.3. The fermentation performance of three strains, Angel brand yeast, bouquet yeast and saccharomyces cerevisiae, on the potato pulp was studied. Angel brand yeast was chosed for doing the further research as it has the strongest ethanol conversion rate at6.78mg/mL.4. Separate hydrolysis and fermentation(SHF) and simultaneous saceharifieation and fermentation(SSF) were performormed on potato pulp. After the single factor experiment, the best SHF technology parameters were as follow: solid-liquid ratio (1:15)、inoculumconcentration (3mL)、nitrogen source (0.8%peptone), fermented20h in the temperature35℃. Under this occasion, the ethanol production rate was 0.18mL/g, the residual sugar amount in the fermentation broth was4.91mg/mL, while the best SSF technology parameters were as following:solid-liquid ratio (1:15)、 inoculumconcentration(2mL).. nitrogen source (0.8%peptone)、 pH value (5), ferment28h at the temperature38℃. Under the circumstances, the ethanol production rate and residual sugar amount of the fermentation broth were0.21mL/g and1.93mg/mL, respectively. The conclusion as followed:发firstly, SSF had1.17times higher ethanol production rate than that of SHF; secondly, SSF’s fermentation period was shorter. SSF consumed total time was40h, while SHF was80h; thirdly, SSF need less Biological inoculation amount. The inoculumconcentration of SSF and SHF were2mL and3mL.5. Studies mainly foeused on the study of the kinetie ProPerty during the Process and conslructed the kinetic models o fthe SSF. The kinetie models:the microbial growth model:dX/dt=0.138943(1-X/0.617919) X; the product formation model: dP/dt=0.056401dX/dt-0.000421X; the raw material consumption model:-dS/dt=0.414181dX/dt+13.755408dP/dt+1.447889X.This model could provide a basis for automation and ndustrialized production.