Overcoming dry burgers: Scientists unlock key enzyme for “juicier” plant-based patties

15 Dec 2023 --- Scientists in Japan have used protein-glutaminase treatment to increase the juiciness in plant-based meat alternatives. The technique also cuts beany off- flavors by 58-85% in such foods on washing. 

The enzyme improves the water-/oil-holding capacity in such products, which is a key juiciness indicator. The strategy can help the F&B industry develop clean label plant-based hamburger patties with enhanced physical and organoleptic attributes that appeal to consumers.

“One of the latest consumer trends driving plant-based meat analogs (PBMA) innovation and NPD is the clean label trend,” Kiyota Sakai, food scientist at Amano Enzyme Inc. Innovation Center, Kakamigahara, Japan, which conducted the study, and one of the co-authors of the research, tells Food Ingredients First.

“Recently, food processing using enzyme catalysis has drawn attention as an attractive strategy to create clean label foods because enzymes are not considered additives if they are denatured or inactivated in the finished food product.”

Enzymes are an integral part of the food and ingredient processing industry and enhance food’s “physical, nutritional, and sensory” properties to formulate highly functional and appetizing clean label products, he adds.

Sakai says enzymes are not considered additives if they are denatured or inactivated in the finished food product.The findings are published in Plos One, a multidisciplinary peer-reviewed journal focusing on rigorous research and ethics based in the US.

A “juicy” concern
Lack of juiciness is an unresolved challenge for PBMAs, flags the study.

One way to enhance the juiciness of PBMA patties is by adding saturated fats to the formulations. Still, adverse health impacts associated with such fats urge manufacturers to replace them with unsaturated vegetable oils. 

However, this does not solve the problem, too, since PBMA patties cannot “retain” unsaturated oils in a liquid state at room temperature, leading to a lack of juiciness.

“To overcome the lack of juiciness in PBMA patties, polysaccharides and proteins are used as binders (mostly in combination) to retain unsaturated vegetable oils,” explains Sakai.

Soy protein and pea protein, which contribute to emulsion stability and reduced oil leakage and purge loss, are also used as binders in PBMA patties, he continues, adding that legume-derived binders release “beany off-flavor compounds that contribute to poor product acceptance.”

Leveraging enzyme power
Protein-glutaminase (PG) is an enzyme found only to change part of the proteins it interacts with and leave other parts unaffected. 

Enzyme-treated texturized vegetable proteins had a more rounded shape compared to control samples (Image credit: Plos One).Interestingly, in food, that means it leaves the taste unchanged, a fact that led the researchers to explore its efficacy on plant-based meat alternatives.

They further tested the method by creating hamburger-type patties and then grilling them, followed by tasting. The samples treated with PG were juicer than those left untreated.

The outer appearance of PG-treated patties closely resembled the untreated samples, except that they had a “more rounded shape.”

The team also examined the treated burgers “more directly” by measuring their liquid-holding capacities and found that PG treatment led to more liquid retention. Further, electron microscopy concluded that PG allows for freeing amino nitrogen, which explains why the enzyme lets burgers hold more liquid. 

In the past, formulators have also used protein glutaminase to improve the solubility of proteins at low pH levels.

Looking ahead
While the findings show potential in helping the plant-based meat industry achieve textures at par with animal-based proteins, Sakai states more must be done.

“While enzymatic reactions are a convenient technology, positive effects may not be obtained due to the influence of ingredients manufacturing conditions.” 

For plant-based formulators, red meat steaks are the toughest to emulate.He adds that further research is needed for the enzyme technology to be used in large-scale applications in the F&B field.

“If there is widespread utility of this technology, the F&B field, particularly PBMA, might be able to develop juicy foods while achieving clean label requirements,” he concludes.

Upsurge in alt-meat texture innovations 
Meanwhile, food companies are working toward overcoming the texture hurdle by innovating with meat analogs. Beneo is doing this with its alternative beef, which is highly heat stable and has a high water holding capacity, which helps to retain its juiciness and succulence, even when baked or fried, leading to a lower fat content.

Among all animal-free protein products, red meat – specifically a “juicy steak” – is touted to be the trickiest product to emulate. Current options contain many ingredients and chemical additives, which, as health concerns spike, companies want to reduce dependency on.

Dehydrated rick flakes are also emerging as an ingredient that enhances juiciness in plant-based meat offerings. For instance, by replacing 15% of the meat in a burger with Meatless textured rice flakes, the yield of the burger improves, making it “bigger in size and juicier” compared to the 100% meat burger, Beneo told Food Ingredients First in October.

By Insha Naureen