What does fluffy actually mean and how can you measure it in a cake?
Researchers at Campden BRI along with members of a research club including Kenwood/Delonghi (the makers of the domestic planetary mixers) and Upfield/Unilever (the producers of cake margarines) have been taking a good look at what makes a good cake. From their own research, Kenwood/Delonghi and Upfield/Unilever explained that consumers recognise fluffiness as an important parameter for cake quality. Campden BRI then set about to attempt to define cake fluffiness and to derive an equation to measure it.
Cake ‘fluffiness’ is commonly used as a desirable quality for cakes and the term is regularly used in adverts and on the packaging of cake products. It is therefore important to be able to quantify fluffiness when developing new and current recipes/processes or when making claims that one cake is fluffier than another. Common descriptors of cake fluffiness include: soft, light, airy, crumbly, springy and moist. It appears that there is no single accepted definition of cake fluffiness, so the challenge to measure cake fluffiness was greater than they first thought.
Is density a factor?
Focusing on what they knew and could already measure, a range of different types of cakes were baked, their textural properties analysed using their TA.XTplus Texture Analyser, and their density measured using their laser volume measuring system (Volscan). Informal sensory assessment was carried out by the project team and comments noted about the different cakes. This helped them identify if a cake was considered fluffy or not, rather than how fluffy it was.
The importance of texture
Next, the textural properties were analysed using a texture profile analysis (TPA) test. TPA is a double compression test which is commonly used for cakes and bread. It not only measures the firmness but also the recovery/destruction of the sample. Firmness is the maximum force reached during the first compression and softness is just the opposite of this i.e. the cake with the lowest firmness value is the softest. After further informal sensory analysis, the results were compared to the TPA results and it was found that there was a strong correlation between the softest cakes and the cakes which were perceived to be the fluffiest. This finding provided the basis for using softness (firmness) as a main parameter in objectively describing fluffiness.
The ‘springiness’ factor
However, they hypothesised that softness was not the only parameter to consider when determining if a cake was fluffy or not. They considered other parameters that were also generated from the TPA, such as springiness. Springiness is defined, from a TPA test, as how far the cake ‘springs’ back between compressions. They noted that some of the softer cakes were ‘claggy’ and it was observed on the Texture Analyser that they were also not as springy. That is, when compressed with a finger, they squash easily, but do not bounce back. It was then decided to use springiness along with softness, as the main parameters for describing fluffiness objectively.
They concluded that ‘fluffy cake is a soft and springy cake’. The next challenge was to incorporate these parameters into an equation that could be used to generate a fluffiness value. With the parameters and the method confirmed, the equation could be written as follows:
Cake quality is described and measured in numerous different ways and varies from person to person and from cake to cake. Fluffiness is just one of the characteristics that can make a cake delicious and desirable. This equation and definition give some clarity to an instrumental measurement of fluffiness. It is an arbitrary method of quantifying fluffiness that works for the cakes studied in this project. The values obtained are meant to provide a relative judgement on cake fluffiness. The units depend on firmness and the value chosen for ‘n’, which is the relative ‘importance’ of springiness. The value of K, which is a multiplication factor, was chosen to give numbers in the region 0 – 100. Through the series of experiments, informal sensory trials and discussion, we determined that the most suitable values were K = 106 and n = 5.
For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.
The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.No-one understands texture analysis like we do!
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