Study On Technology Of Solid-state Fermentation And Evaluation Of Biological Value Of Potato Residue

As one of the largest potato-producing countries，total product in China is at the headof other countries in the world. A large amount of potato residue is produced as theby-products from starch processing industry. The development and utilization of potatoresidue can not only alleviate the status of protein feedstuff shortage， but also realize themaximization of economic， social and ecological benefits.In this experiment， potato residue was taken as the main fermented substrate， andwheat bran as auxiliary materials， different beneficial strains were used in the solid-statefermentation. Appropriate species combination and optimum technological conditions forsolid-state fermentation of potato residue were selected and determined， the nutritionalvalue of fermented potato residue on chickens was evaluated. Eight strains were selectedrespectively as single bacteria strains in solid-state fermentation to get two seed bacteriastrains， contained candida utilis， saccharomyces cerevisiae， saccharomycopsisfibuligera， aspergillus niger， aspergillus oryzae， trichoderma koningii，trichtoderma viride and aspergillus x3， when the content of true protein and crude fiberin the fermented product were taken as the determinant indexes. The appropriate doublestrains combination of yeast and mold strain was selected under the principle ofmicrobial diversity; then bacillus subtilis strains and lactobacillus plan-taru wereintroduced in orders to obtain the best four strains combination after the three and fourstrains fermentation. On the basis of getting the best strains combination， L9(43)orthogonal experiment was used to determine the best inoculation proportion， theoptimum amount of inorganic salt， as well as the optimum fermentation conditions.Finally16healthy adult egg roosters were selected to conduct the digestive and metabolicexperiments with the method of force feeding to evaluate the biological value of fermentedpotato residue. The results are as follows:1.The selection of strains， optimal combination and inoculation proportiondetermine experiments showed that candida utilis had the best protein production ability insingle strain fermentation， the true protein content after fermentation was12.80%，increased by44.95%than untreated potato residue; aspergillus x3had the maximumdegradation ability on crude fiber， the crude fiber content was18.78%with a decreaseddegree by51.26%; the effects of compound strains fermentation were better than single strain fermentation with a strong ability to increase true protein and decrease the crudefiber content， in which the effect of the four strains fermentation was the best. The beststrain combination was composed of bacillus subtilis+candida utilis+aspergillus x3+Lactobacillus plan-taru with the best inoculation proportion of2:3:3:2. Afterfermentation， the true protein was up to14.95%， crude fiber content fell to21.62%.2. The optimal results of fermentation process condition were provided. Thesuitable addition amount of urea， sulfate ammonium， potassium dibasic andmagnesium sulplate in the fermentation system was respectively2%，1%，0.6%and1%; the optimum inoculation quantity， fermentation time， fermentation temperatureand material thickness respectively was15%，72h，28℃and5cm. Under the optimumprocess conditions， the content of true protein and crude fiber after fermentation inpotato residue was to be14.98%and21.06%respectively， while the true protein levelincreased by130.11%and crude fiber degradation was23.39%compared withunfermented potato residue.3. The digestibility test showed that the apparent digestibility of chicken on crudeprotein， crude fiber， and ether extract was increased after fermentation by16.51%，89.64%，89.64%and16.51%respectively with a extremely significant difference(P<0.01). The amino acid apparent digestibility was superior to the unfermented potatoresidue， the apparent digestion rate of total amino acid was increased by24.26%with asignificant difference (P<0.05)， essential amino acid apparent digestion rate wasincreased by23.83%with a significant difference (P<0.05).In conclusion，10strains of bacteria strains were used in the fermentation under theprinciple of microbial diversity in this study. The optimal bacterial combination andinoculation proportion of the four bacteria solid-state fermentation on potato residue werecarried out and the optimal process conditions were also determined. Together with thebiological value of potato residue before and after fermentation on chickens， our currentstudy provides a test basis for the feed resource development and utilization of potatoresidue.