Producing Apple Pomace Feed Protein By Solid State-fermentation

With the rapid development of the apple farming and processing industry, the emissions of apple pomace also increase.Apple pomace has a wide range of development value, but many products are accompanied by the emergence of a large number of residues.It's not only affected the fruit industry in sustainable development, but also caused serious environmental pollution.Since the 20th century, with the rapid world's population growth, the contradictions between supply and demand of protein turned to be more prominent, and feed protein turned to be more tense. It's a good way of utilizing waste products to ferment apple pomace to produce feed protein,it's not only bring no pollution, but also open up new avenues for the lacking protein feed sources, which indicates that apple pomace feed will be the main direction of the development and utilization of apple pomace,It has a deeply significance in the utilization of agricultural wastes, adjustment of agricultural structure and sustainable development, easing the contradiction between the supply and demand of protein and development of Chinese feed industry.In this paper, taking apple pomace of Hengxing Fruit Industry Development Co., Ltd as raw material, its solid-state fermentation production-feed protein has been studied mainly in the following aspects:(1)Determination of the components and indicators of apple pomace(2) Screening and preparation of strains(3) The optimization of single-strain solid-state fermentation process(4) The comparison between single-strain and mixed strain fermentation(5) The optimization of mixed strain solid-state fermentation process(6) The comparison between co-immobilized multi-strains fermentation and conventional fermentation(7) Changes of enzymic activity and their effect on soluble protein content in the process of fermentationConclusions were as follows: 1.The main ingredient of apple pomace:true protein 4.22%, crude fiber 14.72%, crude fat 4.11%,crude ash 4.52%, reducing sugar 11.25%, total acid 1.11%.2. According to the composition of apple pomace and pre-pre-test results,take Aspergillus niger, Saccharomyces cerevisiae and Candida utilis yeast as the starting strain, take true protein content of ferment product as measured indicators, the optimal fermentation parameters of single-strain and mixed strain fermentation were studied systematically. Results of single-strain screening test showed that Aspergillus niger is a good strain for the fermentation.Through the single factor and orthogonal tests, the best conditions of solid-state fermentation of Aspergillus niger to produce feed protein were obtained as follows:urea additive amount 1%(to N% total), material-water ratio 1:3,temperature 28℃,grafting amount 10%,fermentation time 96h, natural pH value. Under this condition, true protein content was 15.46%.3.he results of the comparison test between single-strain and mixed strain fermentation show that the mixed strain fermentation is superior to a single strain fermentation, and identified strains' mixture ratio, namely Aspergillus niger:Saccharomyces cerevisiae is 1:1.Through the single factor and orthogonal tests, the best conditions of solid-state fermentation of mixed strain to produce feed protein were obtained as follows:material additive amount 30g, urea additive amount of 1%(to N% total), material-water ratio 1:3, temperature 30℃,grafting amount 15%, fermentation time 96h, natural pH value. Under this condition, true protein content was 19.86%,4. Under the optimal conditions, the mixed strains were immobilized by sodium alginate and calcium chloride, results of solid-state fermentation showed that true protein content of products raised to 22.38% from 19.86%.5. Changes of cellulose activity, (3-glucosidase activity, xylanase activity, acid protease activity and soluble protein content in the process of solid-state fermentation were investigated. The appeared time and causes of each strain's the maximum of enzyme activity as well as the effects of enzyme activity resulting in product soluble protein content were analyzed.Which provide a reference for the confirmation of investing time and batch in follow-up test and provide certain theoretical basis for the realization of the short-term, high yield of fermentation process.