Plant Proteins

Plant Proteins - How to Improve their Functional Properties with Enzyme Know-How www.biocatalysts.com Plant Proteins - How to Improve their Functional Properties with Enzyme Know-How Authors: Andrew Ellis, Technical and Compliance Director at Biocatalysts Ltd Carolyn Pritchard, Technical Marketing Manager at Biocatalysts Ltd This white paper reviews the continued trend for incorporating plant protein into food products and how enzymes can improve their versatility and functionality including: flavour enhancement and solubility. With a summary of how soy, wheat, pea and rice hydrolysates are being utilised in food formulations to meet the market trends and growing health concerns and sustainability issues. Additionally we include a brief nod to what is coming next in the field of protein. Contents 03 Intoduction 04 Enzymes Unlock the Benefits 05 Established Plant Protein Hydrolysates 06 Plant Protein Hydrolysates - Conclusion and Outlook 07 References www.biocatalysts.com 2 substrate concentration and enzyme dosage. Some of these modifications can be Introduction highly exquisite leading to highly valuable protein or protein-derived ingredients or Proteins are one of the essential components for growth and maintenance of components. In general, the greater the modification of the protein the higher the the human body, driving key functions to ensure good health. Traditionally (in the intrinsic (market) value of the protein; we describe in Figure 1 this as the “plant Western World), protein is consumed from animal derived sources such as meat, protein value chain”. eggs and dairy, but this is changing. The growing global population, consumer trends towards vegetarian and vegan foods and increasing concern for nutritional health are all drivers for exploitation of alternative sustainable sources of food Figure 1. Plant Protein Value Chain protein. A range of new solutions are required to meet the growing global demand for protein including algae, single cell protein, insects and new sustainable crops. While these novel protein sources are still being investigated, plant proteins such as soy, corn, wheat, pulses and lentils and more recently pea are being utilised in novel ways to introduce them into our diet. This drive to incorporate plant protein into everyday food stuff will begin to address the global needs. Over the past decade, the increasing demand for plant-based protein has driven an explosive demand for “plant protein isolates”; these ingredients are incorporated into foodstuffs to enhance the protein content and quality. These protein isolates are extracted from their plant source, through processing to separate from other food macromolecules, namely carbohydrates and lipids. This separation can be achieved through one or more of the following processing methods: mechanical, chemical, thermal or enzymatic. When enzymes are used as a method for separation, this typically means enzymatic hydrolysis of the non-protein components, leaving the protein intact and easier to separate from the other components. For example, this has been demonstrated using different enzymes from Novozymes for extraction of oat protein using cellulase (Viscozyme® L) and rapeseed protein using pectinase (Pectinex® Ultra SP-L)1,2,3. In addition to assisting protein extraction, enzymes can be used to make broad or very specific modifications to plant proteins (post isolation) to enhance their functional, nutritional and chemosensory properties. By far the most significant, in terms of volume of enzyme used for modifying food protein, are the proteases (peptidases) which act by breaking down (hydrolysing) the protein structure. In the process of hydrolysing these large molecules, functional amino groups and hydrophobic patches on the globular surface of the protein are exposed. This process also reduces the molecular weight of the resulting protein or peptides. The properties of the hydrolysed proteins (hydrolysates) are largely dependent on the type and specificity of enzyme used and the degree of hydrolysis (DH); the degree of hydrolysis being affected by the temperature, pH, process time www.biocatalysts.com 3 Table 1. Some examples of commercial enzymes in the manufacture of plant protein Enzymes Unlock the Benefits hydrolysates16, 17, 18, 19. Endopeptidases (endoproteases) hydrolyse plant proteins by acting on ENZYME SUPPLIER TYPE SUBSTRATE EXAMPLE BENEFITS non-terminal amino acids (they tend to act away from the ends of the protein chain). There are numerous endopeptidases that have been applied to the Alcalase® Novozymes Alkaline protease Pea Broad spectrum hydrolysis of plant proteins including trypsin, bromelain, papain, subtilisin protease and fungal neutral endopeptidase. The hydrolytic effect and efficiency of Promod™ 24L Biocatalysts Ltd Casein protease Gluten Low DH with good each endopeptidase is determined by its intrinsic specificity. Commercial enzyme taste and solubility preparations can be highly specific. For example, porcine trypsin hydrolyses only Promod™ 950L Biocatalysts Ltd Microbial & Sulphite- Soya Low molecular weight at the carboxy terminal side of arginine or lysine4 in the protein substrate, whereas Free Alternative to peptides increase Papain solubility papain, containing four different cysteine endopeptidases exhibits broad specificity5. Glutaminase Amano Glutaminase Pea Improve solubility of Exopeptidases catalyse the cleavage of the terminal (last) or next-to-last peptide Amano 500 protein at low pH bond from the termini of a plant peptide or protein, releasing a single Tolerase® G DSM Proline specific Gluten Work at low pH amino acid or dipeptide. Examples of exopeptidases include dipeptidase and endopeptidase resistant to pepsin digestion leucine amino peptidase from Aspergillus oryzae. In most cases, for exopeptidases to work on their target peptide bond the intact globular protein requires pre- or COROLASE® AB Enzymes metalloprotease & Soya Broad spectrum 2TS serine protease protease parallel treatment with endopeptidases (and/or thermal, chemical or physical processing) to open up the globular structure and expose the termini. Often, synergistic effects can be sought through use of combinations of proteases 6,7 from different biological sources used sequentially or in parallel . Such synergism Figure 2. Enzymes ability to can reduce the processing time (producing improved properties faster; thereby unlock numerous innovative leading to cost reduction) and yield different or enhanced properties (relative to the and valuable benefits performance of enzymes derived from a single biological source). Some examples through hydrolysis of of commercial enzymes used for hydrolysing plant proteins are described in plant proteins. Table 1. In order to access the required benefits from hydrolysis from any given plant protein, one must carefully select the most suitable peptidase(s) and the most suitable hydrolysis conditions such as pH, temperature and incubation time. The know-how, to inform such process and product development is beyond the scope of this review. Suffice it to say, that companies active in the development and manufacture of such hydrolysates often work closely with enzyme companies to realise one or more of the many benefits outlined in Figure 2. www.biocatalysts.com 4 foaming and emulsification) enabling its utilisation as an ingredient in food, health Established Plant Protein Hydrolysates and sports nutrition products as well as in animal feed and cosmetic products.11 Soy Protein Hydrolysate The type of gluten hydrolysate produced is The first plant protein to be used specifically as very dependent on the type of protease used. an alternative to animal protein was soy. Soy has A bacterial neutral endopeptidase can achieve become an increasingly popular alternative a high DH and improve the solubility to >70% source of protein, especially for people total protein content, this results in a highly allergic to milk protein. Soybeans have great digestible protein source suitable for elderly potential for use in human food due to their or infant nutritional drinks and feeding young significant levels of high-quality protein and their animals. Due to the high content of glutamic acid unique functional and nutritional properties. present in gluten the use of an additional enzyme; Soy protein supplies all nine essential glutaminase during hydrolysis will enhance the amino acids and provides many functional flavour of wheat gluten hydrolysates producing benefits that have been widely embraced by the food industry. Soy an umami flavour. These hydrolysates can be used as flavour agents in products protein is most commonly used to supplement protein content in vegan meals, like dry soup mixes, stock cubes and seasoning mixes for snack foods and such as burgers and soups, in addition to aiding functions such as water sausages. There is also opportunity to use these properties in the aquafeed retention and adding a savoury flavour to vegan and vegetarian products. industry and pet food as palatents. Historically, soy protein hydrolysates (SPH) were produced by chemical hydrolysis Pea Protein (acid HVP) as a cheap way to produce a product, but it had disadvantages. Soy Pea is becoming an increasingly popular substrate acid HVP had a high salt and monosodium glutamate (MSG) content and can be for manufacturers for producing plant-based carcinogenic. Using enzymes to hydrolyse soy (eHVP) meant it was a more natural protein ingredients. Pea protein has many benefits process, contained no carcinogens and the

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