Study On Pepper(Piper Nigrum L.)Decortication Technique By Solid State Fermentation

White pepper is the main product of pepper(Piper nigrum L.) which is an important tropical spice plant, and decortication is the crucial process in white pepper processing. However, traditional decortication by impregnation needs a long production cycle and causes off-flavor, so the price of white pepper and the development of the pepper industry have been significantly affected in China.which significantly affected the price of domestic white pepper and development of Chinese pepper industry.In this research, in order to solve the problems caused by traditional impregnation method of decortication, such as long cycle and unstable quality, at first, pre-treatments of pepper were studied to detect the effect of pepper decortication rate and pepper color. And then four Aspergillus niger strains were cultured by single and complex incubation and the most effective isolate and optimal incubation method for pepper decortication was screened. Moreoverthe, variation tendency of biochemical indicator during pepper decortication by solid state fermentation method were studied as well as the optimum conditions for enzyme production of the optimal isolate were investigated by single factor experiment and response surface method. Finally, post-processing of pepper were studied. The results were as following:1. The optimal pepper decortication technique(1) The optimal pretreatment way of pepper was hot water immersing at50℃for20min.(2) The results of single and complex incubation methods showed that the single incubation of A. niger CICC40273had the best decortication effect.(3) Optimal medium composions of A. niger CICC40273for solid-state fermentation were as follows:bran:solution=1:1, the solution was pH6.8citric acid and disodium hydrogen phosphate buffer dissolved7.5%lactose,2.5%ammonium nitrate,0.1%ferrous sulfate.2. Variation tendency of biochemical indicator during pepper decortication by solid state fermentation methodThe enzymes results suggested that pectin esterase(PE) and pectin lyase(PL) activity were not examinated in the solid state fermentation method. While, the activity of polygalacturonase(PG), xylanase(XY) and cellulose had a peak at48h and pectinase activity was higher than xylanase and cellulose activity in the solid state fermentation method. Besides, the pH value would reduce with the fermentation time growth.3. Effect of post-processing on pepper color The post-processing of sulphur dioxide had no detectable effect on pepper color, while the white pepper color was not nature enough by the post-processing of chlorine dioxide Therefore, the method was not suitable.