Can we freeze cake batters and what happens to them during storage

Cake batters can be frozen successfully and frozen cake batters may be purchased in order to give customers choice without incurring the wastage that might occur with scratch production where demand is less predictable. For those purchasing frozen cake batters the advantages include:

• no storage or handling of raw materials (apart from that for product decoration);

• no ingredient weighing or mixing on site;

• specialist centralised production improves the chances of optimal product quality;

• improved ability to meet peak demands for a variety of cake products.

Cake batters can be frozen and stored for up to about two or three months before any substantial quality losses are encountered. Cake batters do not freeze until temperatures between —12 and —20°C (11 and 6 °F). The temperature will vary depending upon the level of dissolved salts and sugars because their presence depresses the freezing point of the free water in the batter (Cauvain and Young, 2000). The high sugar concentration in most dried fruits will further depress the freezing temperature of fruit cake batters. The time taken to freeze the batter will be shorter at lower air temperatures and higher air velocities in the freezer.

Care should be taken not to expose the frozen batter to temperatures above its freezing point between production, distribution and storage since unplanned thawing can lead to deformation of the batter in the container.

Some loss of volume will occur with cakes produced from batters that have been deep frozen and stored at —20°C or below for six months (Screen, 1988). This loss of volume will be progressive with increasing storage time. A long storage time will also lead to a firmer and less tender crumb in the baked product. However, with care, the product should still have acceptable volume, crumb texture and taste when baked. The crust of the cake may have a marbled appearance owing to the batter drying out during storage, causing localised excess sugar at the surface of the cake.

The frozen batters should be removed from the deep freeze and can either be given a short defrosting period, or baked immediately from frozen. The defrosting method has no significant effect on cake quality though a slight surface discoloration may occur when product is baked from frozen but this may not be a disadvantage if the cake is to be decorated. Baking conditions should be as normal but if baking from frozen, a longer baking time may be required.

References

CAUVAIN, S.P. and YOUNG, L.S. (2000) Bakery Food Manufacture and Quality:

Water control and effects, Blackwell Science, Oxford, UK. SCREEN, A.E. (1988) Producing frozen cake batters. FMBRA Bulletin No. 3, CCFRA, Chipping Campden, UK, pp. 126-132.

10.5 When we add fresh fruits such as blackcurrants to our cake batters we sometimes find that they fail to keep their colour during baking and often discolour the batter adjacent to the fruit. Can you offer an explanation and a solution to the problem?

This problem occurs because the natural colouring agents in the blackcurrants and many other fruits (see 12.29) are pH-sensitive. This means that they will change colour as the pH changes. For example, anthocyanin, a major colouring component of blackcurrants and other red fruits, will change in colour from red to pink to violet as the pH progressively increases. Blue and violet colours are most likely to occur when the pH is 7.0 or above. To overcome the problem try making the batter slightly more acidic by adding up to 0.6% tartaric acid based on flour weight. This should maintain the basic colour of the fruit without adversely affecting other cake qualities.

The leaking of the colour into the surrounding batter comes from damage to the fruit skins during mixing and depositing. This is difficult to avoid but you should keep the handling of fruit in the batter to a minimum. You may try the addition of frozen fruits as this may help to avoid rupturing the fruit skin. Blueberries have a tougher skin and so are less sensitive to mechanical handling than blackcurrants. However, they are just as sensitive to pH changes.

10.6 Why do cakes go mouldy?

Mould growth is the visible sign that the product has been contaminated with mould spores in an environment suitable for their growth. Such spores can be present in the batter but are effectively killed in the baking process. However, as there are many spores in the atmosphere it is likely that spores settle upon cake surfaces during the cooling and packing processes and if the conditions are favourable they will grow, thus spoiling the product.

The moulds that grow on cakes need water and oxygen to thrive. Ingredients in the cake can 'lock up' water so that it is no longer available for use by the moulds. A measure of the amount of water held by the ingredients is the equilibrium relative humidity, ERH. This is sometimes referred to as the 'water activity'. ERH is measured on a scale of 0 to 100%, water activity on a scale 0 to 1.0. The higher the ERH, the greater the potential for mould growth will be. Cake products usually have an ERH in the range 75-85%. The ERH of a product is different from its moisture content and while the moisture content is a good indicator of the product's eating characteristics, it is the ERH that governs mould growth.

The rate at which the moulds grow is also dependent on the temperature of storage and the level of contamination. In general terms the higher the storage temperature (up to around 33 °C), the faster the mould growth. For example, with an ERH of 86%, the cake would have a mould-free shelf-life of about 10 days for a storage temperature of 21 °C (70 °F) and of about 7 days if stored at 27 °C (80 °F).

It is possible to measure the ERH of a cake product. Representative samples of the product are carefully prepared and can be measured using a water activity meter. Alternatively the product ERH can be calculated from recipe ingredient and baking data. There is software, ERH CALC™ (CCFRA, 1999), which can be used to calculate the ERH of the product from its ingredient data and moisture loss during baking, cooling and storage. It can then be used to determine the mould-free shelf-life of the cake. Such software is invaluable to product development teams in assessing the 'use by' date required by retailers.

Some ingredients have the ability to hold on to water better than others. For example, salt and glycerine are very effective and additions can prevent some of the water in the recipe from being used by the moulds. Increasing sugar content or reducing water content can also extend shelf-life provided the eating characteristics desired are still maintained.

It is important to provide the product post-baking with as clean an atmosphere as possible to reduce the potential for spore contamination. The following suggestions may reduce such contamination:

• After de-tinning allow products to cool without removing any lining paper. All surfaces in contact with the cake should be clean, dry and free from flour dust. Preferably cooling should not take place in the bakery but in a temperature-controlled area.

• If the product is to be cut or decorated ensure that all utensils used are clean and dry and wrap immediately after further processing.

• Store the product in a cool place before dispatch.

Reference

CCFRA (1999) ERH CALCtm, CCFRA, Chipping Campden, UK, www.campden. co.uk.

Further reading

CAUVAIN, S.P. and YOUNG, L.S. (2000) Bakery Food Manufacture and Quality:

Water control and effects, Blackwell Science, Oxford, UK. CAUVAIN, S.P. and SEILER, D.A.L. (1992) Equilibrium relative humidity and the shelf-life of cakes. FMBRA Report No. 150, CCFRA, Chipping Campden, UK.

10.7 In the light of the previous question, why do heavily fruited cakes go mouldy more slowly?

Vine fruits used in heavily fruited products, such as Christmas cakes, Christmas puddings and Dundee cake, have natural mould-inhibiting properties. This is partly as a result of the high natural sugars present in the fruit and this property lowers the ERH of the product and so extends the shelf-life. Also there are traces of natural preservatives in the fruit skins that, while not changing the batter ERH, will improve the product mould-free shelf-life.

Care must be taken, however, with products such as these that the cake or pudding is cooled properly before packing in order to ensure that there is no localised condensation on the surface. Localised condensation provides areas high in moisture and, while the overall ERH of the product may be adequate to ensure the desired mould-free shelf-life, on these localised areas the relative humidity and moisture content can be high enough to allow mould growth at a faster rate.

In Christmas pudding production, the steaming process actually adds moisture to the product rather than removes it as in conventional baking. An allowance must be made for this extra moisture in the final product when determining its ERH and desired shelf-life. Usually Christmas puddings have an ERH below 80% and a moisture content between 25 and 28%. On storage the space in the container above the pudding can become saturated (owing to the evaporation of moisture from the product). If storage conditions fluctuate grossly then moisture can condense and fall onto the product surface either by spot condensation on the packaging film or on the sides of the container. The local atmosphere then becomes favourable to mould growth. If the pudding basins are not adequately filled with the pudding mixture, water enters while they are still boiling and remains to a much greater extent than if the basins/ containers had been well filled and tightly sealed before boiling. When the puddings are boiling the water must not be allowed to cease boiling since if the temperature falls, the puddings are inclined to contract, and water might enter between the container and the outside of the pudding. After steaming the puddings should be cooled with the top surfaces exposed to permit drying out without risk of condensation and allowed to dry for 24-48 hours before packing.

Further reading

CAUVAIN, S.P. and YOUNG, L.S. (2000) Bakery Food Manufacture and Quality: Water control and effects, Blackwell Science Ltd, Oxford, UK.

10.8 Why are we getting mould between our cakes and the board on which they sit?

Mould spores are always present in a bakery, particularly where there may be poor hygiene or an excess of flour dust. Moulds in flour dust are destroyed during baking. The board itself may not be the source of contamination though this cannot be discounted. The cake may have picked up the mould spores post-baking, for example, from a surface in the bakery on which there was flour dust. If the spores are picked up and the cake is subsequently iced they are sealed by placing the cake on the board. The humid conditions created in those circumstances provide the appropriate conditions for the mould spores to germinate.

This problem only occurs with cakes of high ERH. Usually there is a certain amount of air trapped between the board and the cake and if the relative humidity of the localised trapped air is below 75%, mould growth will not take place despite contamination. This can be achieved by painting the base of the cake with a concentrated sugar solution (thus lowering the RH) before putting it on the base board - the basis of the tradition of painting on a fruit puree onto the surface of cakes. A practical, low-cost solution is to raise a fondant to boiling point and paint it over the base of the cake. The syrup is largely absorbed and helps to act as an adhesive.

Eventually moisture migration will take place between the cake crust and crumb, and the whole cake will come into equilibrium. The desired localised reduction in ERH near the base is maintained for a long time to prevent mould growth. Similarly the top surface of a sponge, which may have become contaminated from mould spores in the atmosphere and which is subsequently iced, can exhibit mould growth of this nature.

It is very difficult to eliminate contamination of this type, but it can be reduced by placing the cakes on a clean dust-free surface and covering them with, for example, greaseproof paper prior to packing. The boards should be stored in a dry place and protected from contamination by dust.

Further reading

CAUVAIN, S.P. and YOUNG L.S. (2000) Bakery Food Manufacture and Quality: Water control and effects, Blackwell Science Ltd, Oxford, UK.

10.9 We are experiencing mould growth on the surface of our iced Christmas cakes. This is the first time we have had this problem. Why has it happened?

Christmas and celebration cakes need to be stored with care to avoid mould growth on their surface. This mould growth is caused by localised areas of high moisture on the surface of the iced cake. These localised high-moisture areas can often form because of the presence of undissolved sugar crystals in the icing which makes it hygroscopic. If cakes are stored in a container before they are completely cool, condensation can fall from the surfaces of the container or wrapping material onto the cake, forming an area of high moisture. Such areas are good breeding grounds for mould.

A good way to avoid this problem is to cool the cakes completely and then to wrap them in greaseproof paper before placing them in tins with a few holes for ventilation. The tins should then be stored in a cool, dry place. The cakes should not lose too much moisture during storage because the average ERH will be low and so limit evaporative losses. See also 10.8 and 10.25.

10.10 We are experiencing a 'musty', off-odour developing in our cakes, even though we store them in a deep freeze. Why?

Because of their high sugar content cakes are susceptible to picking up both moisture and odours from the surrounding atmosphere. Care should be taken to keep the areas and surfaces of all containers clean and free from other materials that might impart odours into the atmosphere. In the case of a deep freeze, it is important that any stagnant water accumulating in the drip tray near the evaporator is regularly flushed out with clean water. Such stagnant water provides a breeding ground for moulds and bacteria which can produce odours that are readily absorbed by the cakes.

10.11 When we take our cup cakes from the oven we find that the paper cases they were baked in fall off. How do we avoid this problem?

The tendency for cakes to shrink when baked is the most usual cause of paper cases becoming detached. The shrinkage generally results from the recipe having too high a liquid level. On cooling, the pressure of the steam formed and maintained within the cake while in the oven is reduced and the cake shrinks under normal atmospheric pressure. Because the cases are rigid, they hold their shape and the result is that the cake shrinks away from the case.

This same problem is sometimes found in pound cakes baked in hoops or paper bands. The steam within the cake cannot readily escape from the sides as it does from the surface and so the cake remains softer here. Underbaking or sweating during cooling can also contribute to the fault. Sometimes these cakes have an uncooked core near the bottom.

The remedy is to reduce the liquids in the recipe or by increasing the proportions of baking powder and sugars.

Continue reading here: Why do our Genoese cake sheets tend to lack volume and have cores in the crumb

Was this article helpful?

0 0