Additives are often used in food products to ensure safety and the required level of quality throughout shelf-life. This article describes some of the important groups of enzymes used by the bakery sector.
By Gary Tucker, Head of Baking and Cereals Processing Department, and Sarab Sahi, Rheology and Texture Section Manager, Campden BRI
Additives are present in the final product and have a function in it. They often have an E-number as well as a chemical name. Legally, they have to be listed as ingredients, but E-numbers and chemical names can be off-putting for consumers. The food industry has been trying to find ways to reduce and eliminate additives, and move towards clean label.
In contrast, processing aids have a function during processing, but not in the final product, and have often been destroyed or removed during processing. Such materials do not have to be included on the label. Replacing an additive with a processing aid offers a route to clean labels.
Enzymes are one category of processing aids that offer real opportunities to achieve clean labels. In baked goods, enzymes are destroyed by the high temperatures of baking and so do not have to be declared on the label. This helps bakers to maintain a highly desirable clean label product.
What are enzymes?
Enzymes are proteins. As natural biological catalysts, they are used in baking to help speed up and improve the chemical reactions required in the baking process. Enzymes work quickly, are very efficient and are required in very small quantities – in the range of 10-150 ppm on flour weight.
Enzyme manufacturing is now big business and multinational companies replicate naturally occurring enzymes using modern techniques. Natural enzymes have been used in the past for traditional bread manufacture with extended fermentation times. The natural enzymes from wheat flour break down the starch, proteins, non-starch polysaccharides and lipids, so that the baked bread is better quality, can have more flavor and the nutrients are more available. Enzymes are now seen by the industry as vital processing aids, for example, they help to manage water movement during bread dough processing and provide crumb softness throughout shelf life.
All enzymes need three things to work effectively:
- specific substrates for example starch, protein, lipid
- suitable operating temperatures
- suitable pH conditions
It’s important to understand the specificity of enzyme action so that processing and ingredient conditions can be adjusted to meet those needs. Unlike a typical chemical reaction, enzymes operate at maximum activity at a certain temperature and pH. Conditions that are too far outside these optimum levels will result in poor reaction rates. Enzymes can be expensive, but ensuring conditions are favorable so the enzyme can work efficiently means you only need to use the minimum amount required.
The bakery sector has been actively reducing the amount of fat and sugar in its products in response to consumer demand and government targets. Fat and sugar perform several functional roles during the processing of cakes, biscuits, and pastries, as well as contributing to the final product eating texture and shelf life. If the level of fat or sugar is reduced in baked goods, other ingredients need to be added to mimic these functional roles.
Fat acts as a lubricant, which helps bread and biscuit dough to soften and flow without sticking to surfaces. Reducing fat levels in a recipe can lead to the dough sticking to molders and transfer surfaces, which can increase dough wastage and require expensive cleaning. Emulsifiers can be used to replace some of the fat functionality, but they would have to be added to the list of ingredients as an E-number or lengthy name (e.g. diacetyl tartaric ester of monoglycerides, E4720).
One solution is to use lipase enzymes to generate emulsification materials in situ from lipids naturally present in the ingredients or added to the recipe. Lipases are used in bread and cake manufacture and can reduce the quantity of fat required in a recipe. In a high ratio cake recipe improvements in cake volume were observed with lipase use, although the number of bubbles was similar to the control. This suggests that the larger volume obtained was a result of better bubble stability which allowed greater expansion of the bubbles. Bread with added lipase also showed improvement in volume and lipase in bread rolls resulted in a significant increase in volume and crumb quality.
Like fat, sugar also has many important role in baked goods:
- gives flavor
- acts as a bulking agent
- stabilizes and controls batter viscosity
- influences starch and protein setting temperatures
- provides color through caramelization and Maillard reactions
- acts as a humectant (preservative)
- softens the texture.
Reducing the sugar content of products is high on the list of priorities list for many bakers. The advantages of using enzymes to create sweetness within the baked goods rather than adding sugar extend far beyond clean label. For example, fermentable sugars formed gradually by amylase enzymes help the yeast work in a more controlled way in bread dough. Carbon dioxide is generated slowly, which prevents damage to the delicate network of bubbles created by gluten in the dough. An excess of sugar changes the dynamics of the fermentation process and can cause problems in automated processes. Amylases work slowly to maintain the balance of sugars for fermentation until the yeast is killed at around 55°C. Sugar generation continues for a few minutes after this until the amylases themselves are inactivated by the oven heat. Small quantities of sugar left in the dough help the crust to brown and provide some flavor.
Fiber offers health benefits, so many bakers are attempting to increase the level of fiber in their products. However, fibers such as wheat bran absorb a lot of water and at a slower rate than other components in dough. This causes processing issues because the dough tightens as the fiber absorbs water. Tight dough results in poor quality bread because it is not able to expand properly in response to the yeast action and it does not mold well. An enzymic solution containing xylanases is available and is now used in most industrial bread manufacture. Xylanases cut some of the linkages of large fiber chains to release low molecular weight sugars and water. This helps to soften the dough slowly so it can be processed with fewer issues.
There are several other enzymes used in bakery products that give specific benefits. Glucose oxidases and lipoxygenases both help with gluten development, and lipoxygenase also makes bread crumb whiter. Soya flour is a natural source of lipoxygenase and is often a major component in the improvers used by bread bakeries. Transglutaminase can be used to strengthen wheat flour proteins.
Proteases act on proteins to break the chains down into small peptides and amino acids. Biscuit dough can be softened using proteases, making it flow better. This is useful when the dough must fill a mold or flatten out – for example, when baking cookies. However, a protease – like any enzyme – will carry on working until it runs out of substrate or the external conditions become unfavorable. This can cause manufacturing problems if line stoppages occur and if scrap dough is added back into the fresh mixes.
Acrylamide is believed to be a human carcinogen and is formed in high–carbohydrate products that are subject to high temperatures. In most cases, acrylamide formation involves a reducing sugar and an amino acid. One of the more recent additions to the list of commercially available enzymes is one that reduces the formation of acrylamide during baking. The enzyme is called asparaginase because it acts on the amino acid asparagine, which is involved in the formation of acrylamide. By reducing the concentration of the amino acid it is possible to reduce the amount of acrylamide formed.
We may see significant changes in the way enzymes are used in food manufacture in the near future. The EU is in the process of compiling a long list of permitted enzymes that can be placed on the market and used in food and specific EU legislation on the use of enzymes in food may be introduced for the first time. While it remains to be seen what the outcome of European Union Regulation 1332/2008 will be, it is safe to say that it will have far-reaching implications for the baking industry.
Regardless of changing regulatory requirements, enzymes used as processing aids in the baking industry are here to stay. Enzymes are a must have in a competitive marketplace, thanks to their functional capabilities, clean label properties, and ability to create more efficient processes and reduce costs. The huge advantage of using enzymes is that many are naturally occurring components in bakery ingredients such as wheat and soya flour.
We have been helping clients use enzymes in baking for many years, for example, investigating enzyme blends, optimizing processing conditions and their effects on dough and batter during processing, and assessing the impact on product quality of the finished baked goods. We can also help you to optimize your processing conditions to allow you to get the most out of your enzyme systems.