Enzymes as processing aids in bakery products

15 January 2021 | Sarab Sahi, Rheology and Texture Section Manager

Enzymes are naturally occurring materials in plants and animals and are widely used in the manufacture of bakery and other products that make use of modern food processing plants. They allow manufacturers to make bread, cakes and biscuits that have, for example, the texture a consumer expects as well as the desired shelf-life. However, the importance of enzymes is not always appreciated and there is still some mystery attached to what enzymes are and what they do, particularly as they are not mentioned on the ingredient list. This can make both the manufacturers and consumers wary about their use. Here we’ll provide a basic introduction to enzymes, their properties and how they are being used to benefit the nutritional properties of bakery products.

A basic introduction to enzymes

The wide occurrence of enzymes is well known and in nature animals and plants can obtain and use energy very quickly due to the presence of these biological catalysts. In chemical terms, enzymes are proteins which have catalytic activity due to the correct arrangement of amino acids (protein building blocks) in space to ensure only a certain type of substrate will fit and attach to form an enzyme/substrate complex. This lowers the energy of the reaction and speeds up the rate of reactions, thus saving time and improving efficiency. Only a small amount of an enzyme is needed to bring about the transformation of a large number of substrate molecules. This is because the enzyme is released to repeat the transformation when the by-products of the reaction are generated. Hence, enzymes carry on working until their substrate is exhausted or environmental conditions become such that the enzymes are denatured, and the activity falls off rapidly. Important factors that influence enzyme activity include temperature, pH, ionic concentration and substrate availability. The inactive residues of the enzymes remain in the final product and are harmless.

As mentioned earlier, enzymes occur naturally in most raw materials used in food production such as cereals and legumes. Wheat is known to be rich in endogenous enzymes, with several playing important roles in traditional bread making processes. The concentration of these endogenous enzymes is usually low but can vary depending on the weather conditions close to the time of wheat grain maturation. There are also numerous commercially available enzymes, or exogenous enzymes, that can be added to recipes to boost the levels of endogenous enzymes to achieve the desired effect within the limits of the manufacturing process. These include alpha-amylases, proteases, lipases, oxidases and hemicellulases to name a few. Enzymes break down or modify key food components such as starches, proteins, fats and non-starch carbohydrates such as hemicelluloses.

Measurement of enzymes

The measurement of enzyme activity in raw materials, such as wheat flour, can be difficult as they are present at low concentrations. In wheat flour, the bakers are typically interested in the activity of key enzymes including those just mentioned: alpha-amylases, proteases, lipases, and hemicellulases. We use two methods here at Campden BRI to measure the naturally occurring cereal alpha-amylase activity in flour. One, called the falling number test, relies on the marked reduction in the viscosity of a flour/water slurry as the enzyme action rapidly reduces the molecular size of the starch chains. A more direct method is the Ceralpha assay method using a commercial kit containing a reagent with chemical groups that are specifically hydrolysed by alpha-amylase. The quantity of the chemical group is measured and directly relates to the level of alpha-amylase in the sample analysed. This method is applicable to ground wheat, white wheat flours, malt flours and fungal alpha-amylase preparations.

Several indirect methods indicate the presence of enzymes in flour. For example, the physical change in the dough properties or those of a batter system can be measured instrumentally using texture analysers or viscometers. As the enzymes degrade the structure forming compounds, such as starches and proteins, the physical properties will change. Similar instrumental techniques can be used to measure the effect of an added enzyme to a dough, such as a protease or a hemicellulase.

For example, in bread dough, a gradual formation of fermentable sugars helps the yeast work in a more controlled way. Slow generation of carbon dioxide prevents damage to the delicate network of gas cells created by gluten in the dough.

Application of enzymes in the baking industry

The baking industry faces a number of challenges in providing products that meet the needs of modern consumers. This is not easy for an industry in which many of its products are indulgent because of their high levels of fat and sugar. It’s true, however, that industry does not use fat and sugar without good reason. Both have several functional roles during processing as well as contributing to the final product’s eating texture and shelf-life. In addressing these needs, one of the solutions available to the baking sector is the use of enzymes as processing aids.

Fat has many properties that make it an essential ingredient for baked goods, including:

stabilisation of gas bubbles
retention of water, and
softening of texture

Therefore, despite it being desirable from a health perspective, reducing the fat levels in a recipe can lead to many problems. Emulsifiers can be used to reduce the fat and oil content because they can replace some of the fat functionality. However, they appear on the ingredients label with an E-number, and while the industry knows this means they are a safe ingredient, consumers have a less tolerant policy. One solution is the use of lipase enzymes to generate emulsification materials in situ. They are used in bread and cake manufacture and can reduce the fat required in a recipe. It is important that enough of the specific fat substrate is present for the enzyme to work effectively in addition to the correct conditions of pH, temperature and sufficient time to work.

Sugar also has an important role in baked goods, conferring properties that include:

providing sweetness
stabilising and controlling batter viscosity
influencing the starch and protein setting temperatures
providing colour through caramelisation and Maillard reactions
acting as a humectant (preservative), and
softening the texture

However, sucrose has received bad press recently to the extent that, in many ways, it has taken over from fat as the primary diet and health concern. Sugar created enzymically in situ has significant advantages over added sugar, and not just because it helps a product appear as clean label. This is where amylase enzymes come into play in bread production. For example, in bread dough, a gradual formation of fermentable sugars helps the yeast work in a more controlled way. Slow generation of carbon dioxide prevents damage to the delicate network of gas cells created by gluten in the dough. Too much sugar could result in excess carbon dioxide and over-inflation of gas cells, which could subsequently rupture. 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 contribute to crust browning and provide some flavour.

Also on the diet and health agenda is fibre. Fibre materials are beneficial to our health and efforts are made to include them into bakery products. However, fibres such as wheat bran absorb a lot of water and do so more slowly than other components in dough. This causes processing issues with tight dough that does not mould well but also resists expansion by yeast action resulting in poor quality bread. An enzymic solution with xylanases is available and is now used in most industrial bread manufacture. Xylanases cut some of the linkages of large fibre molecules to release low molecular weight sugars and water. This helps soften dough slowly so it can be processed with fewer issues. The fibre materials are still available as a dietary benefit.

There are several other enzymes used in the manufacture of bakery products that confer specific benefits. Glucose oxidases and lipoxygenases both help with gluten development through their oxidation potential, and lipoxygenase has a further benefit in that it makes bread crumb whiter. Proteases can soften dough through breaking down the gluten networks, making it flow better, which is useful when the dough must fill a mould or flatten out as with pizza bases. However, it is the amylases, lipases and xylanases that find the greatest use in bakery product manufacture.

The future for enzymes

Looking to the near future, however, there are significant changes ahead in terms of the use of enzymes in food due to the changing legislative landscape. For the first time, there may be specific EU legislation on the use of enzymes in food. 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. 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 as processing aids in the baking industry are here to stay. Their functional capabilities, clean label properties, ability to create more efficient processes and reduce costs means they are a must-have in a competitive marketplace. The huge advantage of using enzymes is that many are naturally occurring components in bakery ingredients such as wheat and soya flour. They have played a major role in traditional bakery products such as sourdough and bread made using sponge or brew systems. Enzymes will be destroyed by the high temperatures involved in the baking process helping bakers to maintain a highly desirable clean label image for the product.

We’ve been active in the application of enzymes to baking for many years. We have the expertise and facilities to investigate and analyse enzyme blends and research their effects on dough and batter during processing as well as testing finished baked goods to assess product quality. With this experience we can help manufacturers get the most out of enzyme systems by understanding the needs of the enzymes so that processing conditions can be optimised. Do get in touch to find out how we can help – we’d love to hear from you!

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