Rising global temperatures have forced humans to adopt novel agricultural practices to sustainably meet food demands. Extracting protein from plant by-products may help supplement meat protein and reduce agricultural waste.
One of the challenges with plant-derived proteins is that compared to meat, they are not as nutrient-dense or as easily digestible, explained Xuezhi Bi, Principal Scientist and Group Leader at A*STAR’s Bioprocessing Technology Institute (BTI). Moreover, allergens in plant products such as soy and wheat pose a health risk to certain people, leaving food producers in search of safe and nourishing protein alternatives.
Researchers have pointed to cottonseed meal (CSM) as a viable option. Millions of tonnes of CSM are produced as a by-product of harvested cottonseed oil and are typically used as feed for livestock due to their high protein content.
However, CSM-based food products aren’t ready to line supermarket shelves since the plant protein contains a toxic compound called gossypol, which makes it unsuitable for human consumption.
Bi and colleagues therefore optimised a method to efficiently remove free gossypol during the CSM extraction process by leveraging a unique chemical property of the compound. Gossypol is soluble in an alkaline solution while the extracted protein can be precipitated under acidic pH conditions. Subsequently, gossypol can be filtered out as flow through, leaving behind purified CSM protein.
“Our approach was to develop a time-efficient and scalable protein extraction method by minimising processing complexity and using readily available reagents that are generally regarded as safe,” said Bi.
The gossypol removal treatment that the team developed and optimised takes about three hours, while the entire extraction process of highly purified CSM can be completed in a day. The technique is also gentle on CSM proteins, which is important for maintaining high flavour and digestibility.
“Our protein extraction process reduces free gossypol levels to about 90 times below US Food and Drug Administration (FDA) permitted limits,” said Bi, who added that the purified CSM protein surpassed the nutritional value of pea protein and is predicted to be hypoallergenic.
“The next step forward will be to optimise and scale up the process for industry collaborations in the alternative protein ecosystem and implement large-scale production of CSM protein-based food products,” Bi concluded.
The A*STAR-affiliated researchers contributing to this research are from the Bioprocessing Technology Institute (BTI).
