Fermented onion could make plant-based meat more 'meaty'

Plant-based alternatives such as tempeh and bean burgers provide protein-rich alternatives for those who want to reduce their meat consumption. However, the challenge has been replicating the flavours and aromas of meat, with companies often relying on synthetic additives.

A study in ACS’s Journal of Agricultural and Food Chemistry unveils a potential solution: onions, chives and leeks that produce natural chemicals akin to the savoury scents of meat when fermented with common fungi.

Often, precursor ingredients found in meats are used to make plant-based alternatives taste meatier. These flavourings are made through synthetic processes, so many countries will not allow food makers to label them as ‘natural’. To access a ‘natural’ plant-based meat flavour, the flavouring chemicals need to be physically extracted from plants or generated biochemically with enzymes, bacteria or fungi.

YanYan Zhang and colleagues wanted to see if fungi known to produce meaty flavours and odours from synthetic sources could be used to create the same chemicals from vegetables or spices.

The team fermented various fungal species with a range of foods and found that meaty aromas only came from foods in the Allium family, such as onions and leeks. The most strongly scented sample came from an 10-hour-long fermentation of onion using the fungus Polyporus umbellatus, which produced a fatty and meaty scent similar to liver sausage.

Using gas chromatography-mass spectrometry, the researchers analysed the onion ferments to identify flavour and odour chemicals and found many that are known to be responsible for different flavours in meats. A chemical they identified was bis(2-methyl-3-furyl) disulphide, a potent odorant in meaty and savoury foods. The researchers say that the high sulfur content in alliums contributes to their ability to yield meat-flavoured compounds, which also often contain sulfur.

According to the researchers, these onion ferments could one day be used as a natural flavouring in various plant-based meat alternatives.

Image credit: iStock.com/PDerrett