Looking for functional proteins

  • 13 November 2018
  • Door: Steven Cornet, Jan Bühler en Theo Verkleij, Wageningen Food & Biobased Research

Product developers of food producing companies are continuously looking for new flavors, unique textures and solutions to improve the product structure. The use of proteins can provide solution to these challenges. Proteins and protein based ingredients can add both nutritional value and functionality to a food product. The demand for functional proteins is growing steadily.

While the nutritional value is largely set by the amino acid composition of the protein, the functionality depends primarily on the protein structure combined with the product composition. Protein functionality is therefore more complex to control.

Proteins are versatile compounds that enable them to fulfil many roles in a food product. For example, proteins are known to act as emulsifiers and are used to stabilize emulsion type foods such as ice creams or salad dressings. Similarly, proteins are used to create various stable foams such as chocolate mousse or cappuccino foam. Also very well-known, are the structuring abilities of dairy proteins, which are utilized in cheese and yoghurt. pH induced gelation is used to make yoghurt from milk under acidic conditions. A range of enzymes is also capable of creating a gel from proteins by cross-linking the polymers.

Novel protein sources

Then it comes to the use of novel proteins, two main routes can be identified: integrating novel protein sources into existing products, or creating new products with functional proteins from novel sources. In recent years, novel protein sources with excellent nutritional value have been identified. An example is insect protein. The main challenge here is to apply the insect protein in products that appeal to the consumer.

Lupine seeds are another great source of protein cultivated in Europe that are increasingly used in food products. Examples are lupine milk, ice-cream, and yoghurt. Another less conventional protein source are fungi, which produces myco-protein via fermentation. Myco-protein has already been used extensively in Quorn.

Novel protein sources are often found in side streams of other products. For example, after the harvest of sugar beets, the sugar beet leaves are left on the land as fertilizer. Although this is a way to reduce waste, a more efficient way to process the leaves could be to extract the protein they contain. The amount of protein present in a single leaf is low, but because the total volume of leaves is large, the potential amount of protein is substantial. The main protein in leaves is rubisco. Recent developments in the extraction of rubisco from sugar beet leaves have made it into a promising source of protein.

A current trend in food industry is to make products ‘gluten free’. However, since gluten has excellent network forming capabilities (such as in bread dough), gluten is difficult to replace. A potential gluten replacer is a protein from corn called zein. Its properties somewhat resemble that of gluten, but the commercial availability is limited.

Application of proteins for functionality

Proteins can clearly be used to create or stabilize most of the structures found in food products. However, the functional properties of proteins depend largely on the other ingredients present in the product. For example, the pH or salt content of a product can affect the solubility of the protein. It is therefore important to know how the functionality of the protein depends on changes in composition as this can make production processes more robust.

Some proteins such as those from soy or whey have the special property of forming a gel when heated. They can thus be used to control the firmness of a product, or to create new food structures by themselves. However, the interaction between different proteins can influence their behavior and performance. In some cases, the mixing of proteins can result in synergy. For example, mixed gels can benefit from synergetic effects with the mixed gel being stronger than the sum of its parts. The production of meat alternatives also often utilizes a mixture of proteins, by mixing texturized soy protein with gluten to obtain a meat like structure.

Choosing the right protein

Whether you are trying to explore new protein sources to integrate them in existing food products, or if you are looking to create new products from known proteins, knowledge of their functional properties is always the key. It can help in choosing the right protein for the intended application or offer more sustainable, healthy and economic alternatives to existing proteins. Creating that knowledge is and will continue to be a great challenge for food producers and researchers alike.

Source: © Wageningen Food & Biobased Research