| China is the largest apple producer and apple juice concentrate exporter around the world. About 2million tons of apple pomace were produced from apple processing industry every year. However, the apple pomace may cause environmental pollution and resource waste if it could not be effectively used.Meanwhile, China has been in serious shortage of protein feed with the rapid development of Chinese livestock industry and million tons of fish meal and soybean meal has been imported in recent years.In this paper, basic nutrient substances of dry apple pomace from seven major apple producing provinces in China were determined. In addition, the differences of origin and application prospect of these substances were also discussed. Aspergillus niger was adopted as fermentation strain from Phanerochaete chrysosporium,Candida utilis and Saccharomyces cerevisiae because of its excellent ability of protein productivity. The optimal process conditions for apple pomace fermentation by Aspergillus niger were obtained by orthogonal design method. Nutrient-rich apple pomace SCP was obtained though the optimal process conditions. The crude protein content and crude fiber content in apple pomace SCP are in accord with the regulation of protein feed; ICR mice was chosen as model animal to evaluate the nutritional effects and safety of the apple pomace SCP. The main conclusions of this paper were as follows.1. Analysis of basic chemical composition in apple pomace from major apple producing provinces in China showed that: moisture contents of dry apple pomace from seven major apple producing provinces in China were ranging from 3.71% to 8.96%, ash contents were ranging from 1.21% to 2.96%,protein contents were ranging from 5.00% to 8.75%,fat contents were ranging from 3.71% to 6.21%,fibre contents were ranging from 20.07% to 21.91%, sugar contents were ranging from 5.80% to16.05%, starch contents were ranging from 0.48% to 5.26%, polyphenol contents were ranging from0.29% to 0.61%, amino-acid contents were ranging from 4.80 % to 5.55%; among trace elements, Zn contents were ranging from 7.71 to 11.15 mg·kg-1, Fe contents were ranging from 50 to 128 mg·kg-1,Mn contents were ranging from 9.17 to 19.88 mg·kg-1, Se contents were ranging from 0.06 to 0.61mg·kg-1, Cu contents were ranging from 6.21 to 41.73 mg·kg-1. Among heavy metal elements, As contents were ranging from 0.92 to 2.04 mg·kg-1, Cd contents were ranging from 0.01 to 0.03 mg·kg-1,Pb contents were ranging from 0.64 to 2.41 mg·kg-1, the heavy metal elements contents are all conform to the regulation of protein feed. Apple pomace contains abundant crude fiber, polyphenols, fat and other substances. In addition, it can also be utilized in food and cosmetic filed to extract natural health materials, such as dietary fiber, polyphenols.2. The result of apple pomace fermentation strains isolation showed that: Aspergillus niger has a better ability of protein production in apple pomace fermentation than Phanerochaete chrysosporium,Candida utilis and Saccharomyces cerevisiae. Aspergillus niger thrive in the apple pomace medium and cannot be easily infected by harmful bacteria. The protein content in apple pomace could reach to20.03% if fermented by Aspergillus Niger while 11.70% to 19.27% protein content could be obtainedif fermented by the mixture of Aspergillus niger and Candida utilis. Apple pomace fermentation by Aspergillus niger was more time saving and cost saving than fermentation by the mixture of Aspergillus niger and Candida utilis.3. The results of optimization for apple pomace solid-state fermentation process and product quality analysis showed that:the optimal conditions for apple pomace fermentation by Aspergillus niger were: fermentation time 6 d, ermentation temperature 32 ℃, inoculum of Aspergillus niger 10%(V/W),solid-liquid ratio 1:3.5. After fermentation, crude protein content in apple pomace was increased to33.56%, crude fiber content in apple pomace was reduced to 13.53%, essential amino acids content in apple pomace was increased to 50.40 mg·g-1. After fermentation the content of trace elements(iron,copper, zinc, manganese, selenium) were increased in apple pomace, the content of heavy metal elements(As, Pb, Cd) were 1.23 mg·kg-1, 1.75 mg·kg-1, 0.03 mg·kg-1 respectively, which were under the limited numerical( 2.00 mg·kg-1, 5.00 mg·kg-1, 0.50 mg·kg-1) in feed hygiene regulation.4. The results of nutritional and healthy effects of APSCP evaluation by ICR mice model showed that: It has a beneficial effect to health promotion by adding 30% of APSCP to mice diet,but 30% of AP added in mice diet did some damage to mice’s health. Moderate APSCP in animal feed play an important role in grain saving and cost saving of animal husbandry. |
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