Background
About 27% of methane emissions comes from the enteric fermentation of ruminant livestock. Although methane accounts for only 11% of total greenhouse gas (GHG), it is 28 times more powerful than carbon dioxide in the warming effect over 100 years. Previous studies showed that plant tannins, and organic and fatty acids could reduce methane emissions from livestock. The US produces 1.5 million tons of grape pomace (GP) per year, however, limited studies focused on the use of grape pomace as a source of anti-methanogenic compounds.

Methods
In this study, the chemical compositions related to the methane emission reduction effect of three types of grapes were evaluated.

Results
Results showed that the oil content of wet GP (WGP from red grape), dry GP (DGP from red and white grape mix), and ground dry GP (DGGP from red and white grape mix) were 4.33, 5.73 and 4.57% (wt/wt dry basis), respectively, but there was no significant difference (p< 0.05) among them. WGP contained the highest moisture (62.8%) among the three GPs. Both total phenolic content (10.2 mg/g defatted dry base, DDB), extractable (12.5 mg/g) and non-extractable (37.7 mg/g) condensed tannins of WGP were about twice as much as that of dry GPs. There was no significant difference in total organic acids (106-115 mg/g), but the malic acid and succinic acids of dry GP were slightly higher than the WGP. Therefore, the WGP would be a good candidate for reducing enteric methane emissions.

Significance
This study provides a pivotal data foundation for both upcycling value-added by-products from the US wine industry and reducing methane emissions for a sustainable and eco-friendly agriculture and food supply chain.

Climate-smart technology & Agri-Food 4.0

Ermias Kebreab

Appearances