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Acta Prataculturae Sinica ›› 2022, Vol. 31 ›› Issue (7): 96-110.DOI: 10.11686/cyxb2021260

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Solid-state fermentation with Trichoderma koningii improves nutritional value of tea dregs

Yi-yan CUI1(), Jia-zhou LI1, Zhi-mei TIAN1, Dun DENG1, Hui-jie LU1, Zhi-chang LIU1, Ting RONG1, Xian-yong MA1,2()   

  1. 1.Institute of Animal Science,Guangdong Academy of Agricultural Sciences,State Key Laboratory of Livestock and Poultry Breeding,the Key Laboratory of Animal Nutrition and Feed Science in South China,Ministry of Agriculture,Guangdong Provincial Key Laboratory of Animal Breeding and Nutrition,Guangdong Engineering Technology Research Center of Animal Meat Quality and Safety Control and Evaluation,Guangzhou 510640,China
    2.Maoming Branch,Guangdong Laboratory for Lingnan Modern Agriculture,Maoming 525000,China
  • Received:2021-06-29 Revised:2021-09-08 Online:2022-07-20 Published:2022-06-01
  • Contact: Xian-yong MA

Abstract:

The purpose of this experiment was to study the solid-state fermentation of tea dregs (TDs) by Trichoderma koningii to improve the nutritional value of TDs, and identify the optimal fermentation conditions. A series of single factor experiments was used to optimize the substrate ratio (TDs∶corn meal=6∶4, 7∶3, 8∶2, 9∶1), solid∶liquid ratio (3∶7, 4∶6, 5∶5, 6∶4, 7∶3), inoculation amount (2%, 4%, 6%, 8%, 10%), fermentation temperature (25, 28, 31, 34, 37 ℃), and fermentation time (0, 2, 4, 6, 8, 10, 14, 22 d) in fermented TDs. The optimum fermentation conditions of TDs were identified by an L9 (34) orthogonal test with substrate ratio, fermentation temperature, inoculation amount, and fermentation time. The contents of crude protein, ether extract, reducing sugar, flavonoids, saponins, and caffeine of different fermentation combinations were determined, and the multivariate scores of different groups were calculated. After determining the optimal conditions, a comparative experiment was carried out to compare the nutrients, active substances, and free amino acid contents of the TDs before and after fermentation. It was found that: 1) In the single factor tests, the multivariate scores of the following were the highest: substrate ratio 7∶3, solid∶liquid ratio 5∶5, inoculation amount 8%, fermentation temperature 31 ℃, and fermentation time 6 d. 2) The orthogonal test indicated that a substrate ratio of 7.0∶2.5, inoculation of 7% (1×107 spore·mL-1), and a solid-liquid ratio of 5∶5 at 31 ℃ for 6 or 7 d would produce the optimal result. 3) Compared with unfermented TDs, the contents of crude protein, reducing sugar, flavonoids, caffeine, various free amino acids, essential amino acids∶total amino acids and flavor amino acids∶total amino acids of fermented TDs (under optimal conditions) were significantly increased (P<0.05), the saponin content was significantly decreased (P<0.001), and the ether extract content had no significant difference between fermented or unfermented TDs (P>0.05). No significant differences in nutrients or levels of active compounds were detected in fermented TDs for 6 or 7 d (P>0.05). In brief, the solid-state fermentation by T. koningii can improve nutritional value in TDs.

Key words: Trichoderma koningii, tea dregs, solid-state fermentation, nutritional value