Researchers have determined that processing soy increases its nutritional quality, affirming its status as a valuable source of protein for plant-based foods. 

Scientists from Unilever and Wageningen University challenged the concern that processing soy products makes them less nutritious, proving it false. 

“For the first time, a study comprehensively finds that the protein quality of soy used in plant-based foods is not compromised during processing methods. In fact, processing soy slightly increases the protein’s nutritional quality,” Amelia Jarman, Unilever’s future health and wellness science and technology director tells FoodIngredientsFirst.

The scoop on soy

Soy, the most common protein alternative, is confirmed to have a rich protein content for plant-based foods.Soy is a standard ingredient in many plant-based meats due to its high protein content compared to other plant-based ingredients. However, it must undergo many processes – such as soaking, grinding and heating for soy milk – before being used in alternative products. 

Consumers have previously had reservations and mixed feelings on the processed ingredient and whether the nutrition content suffers. 

Most alternative meat options on the market are made from vegetable protein, with soy being the most common. Plant-based foods have been proven environmentally beneficial, and more consumers are transitioning to being vegan or the increasingly popular, flexitarian demographic, which makes up 42% of the plant-based market, FoodIngredientsFirst previously reported. 

Therefore, scientists have aimed to end speculation if soy is properly nutritious to aid in the continued growth of the alternative protein market. Soy maintaining its high protein levels creates more opportunities for the ingredient in the plant-based food industry. 

“We hope this research puts to bed concerns that soy-based plant-based alternatives are an inadequate source of protein, and that it encourages consumers to continue to embrace a more plant-based diet,” says Jarman.

The science of soy
Soybeans experience dehulling and fat extraction to create soybean flour and then remove soluble carbohydrates from this to make soy protein concentrate. 

The scientists performed studies that investigated the digestibility of indispensable amino acids scores (DIAAS), a method to assess protein quality. The scores increased from making tofu, soy flakes, soy hulls, soy flour, soy protein isolate, soybean, soybean meal and soy protein concentrate to soymilk. 

Most soy products had high protein quality scores, and the researchers could increase or decrease the quality through processing and post-processing conditions. 

The broad variations in protein quality scores from the soy products indicate that variations in protein quality scores may be attributed to various forms of post-processing, such as additional heat treatment or moisture conditions. 

Little has been researched previously on the effect of processing methods on protein nutritional quality. According to the researcher, this study “proves that meat-free alternatives can fulfill our bodies’ protein requirements.”

Researchers from Unilever and Wageningen University found a way to increase and decrease soy protein levels through processing the ingredient in different ways.

“Until now, the data on protein quality of soy had been scattered throughout scientific literature. This review has brought together all the available data to provide us with a total picture of the impact of different stages of processing on the protein quality of soy,” states Jarman. 

Contesting soy protein’s nutrient profile
Controlling soy’s protein level opens doors for plant-based food manufacturers to explore their products’ nutritional and protein content. Alternative proteins are only expected to grow, “Plant-based: The canvas for innovation” is Innova Market Insights’ second Top Ten Trend for 2022. 

However, earlier this year, a study found that peptides from plant proteins such as soy and wheat gluten used in alt-chicken are in fact less water-soluble than animal protein – and thus are not absorbed as well by human cells, according to the American Chemical Society.

More research needs to be done to “quantify to what extent processing and post-processing impact protein quality of plant-based protein-rich products relevant for human consumption,” concludes the new study.