Protein Enhancement of Yam (Dioscorea rotundata) Peels with Single-or Co-Inoculation of Aspergillus niger Van Tieghem and Trichoderma viride Pers Ex Fr. Under Solid-State Fermentation

L Yafetto,E Birikorang,G T Odamtten,S Adu

doi:10.4314/gjs.v61i2.3

L Yafetto, E Birikorang + Show 2 more

Open Access

https://doi.org/10.4314/gjs.v61i2.3

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Abstract

This study assessed the protein enrichment of sterilized and non-sterilised yam peels substrates fermented for 21 days at 25°C with mono- and co-cultures of Aspergillus niger and Trichoderma viride. Yam substrates were harvested at 0, 7, 14, and 21 days intervals for protein content and other chemical composition analyses. Results showed an overall percentage increase in protein contents of sterilised yam peels by 71.80% for A. niger, 58.03% for T. viride, and 80.60% for co-culture of A. niger and T. viride. Protein contents in non-sterilised yam peels increased by 113.30%, 95.00%, and 96.45% for A. niger, T. viride and co-culture of the test fungi, respectively. The significantly (p ≤ 0.05) higher protein contents of the fermented, non-sterilised yam peels suggest possible successional microbial colonization of the substrate, and their combined, cumulative contributions to protein enhancement, unlike the sterilised yam peels. Ash content significantly (p ≤ 0.05) increased in both sterilised and non-sterilised yam peels. These findings underscore the fact that, through fungal bioprocessing, protein contents of yam peels can be significantly enriched for value-addition. The practical implications of the findings are discussed

Highlights

Yam is cultivated for the tubers, which may be subterranean (e.g. Dioscorea rotundata), or aerial (e.g. Dioscorea bulbifera), serving dual agricultural functions as source of food and planting material (Hahn, 1995; Ile et al, 2006)
After 21 days of fermentation, there was asignificant increase in the mean protein contents of sterilised substrates inoculated with A. niger (13.26±0.10) and coculture of A. niger and T. viride (13.94±0.09) (Table 3) and the corresponding increase in protein contents were 71.80, 58.03 and 80.60%, respectively (Table 1)
After 21 days of fermentation, the protein contents of the substrate inoculated with A. niger, T. viride and co-cultures of A

Summary

Introduction

Yam is cultivated for the tubers (storage organs), which may be subterranean (e.g. Dioscorea rotundata), or aerial (e.g. Dioscorea bulbifera), serving dual agricultural functions as source of food and planting material (Hahn, 1995; Ile et al, 2006). The application of solidstate fermentation using fungi continues to be the most simple, but effective, easy-touse biotechnological technique employed to convert agro-lignocellulosic residues of discarded agro-industrial wastes such as yam peels into value-added, protein-enriched products (Sadh et al, 2018; Yafetto, 2018). These protein-enriched products are potential solutions to inadequate animal nutritional needs of consumers around the world. The application of solid-state fermentation to convert agro-industrial wastes into proteinenriched feed is beneficial in two ways: (i) it curtails environmental pollution, and (ii) it improves the nutritional quality of animal feed, which improves nutrition in humans (Aruna et al, 2017)

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