Fruits have a higher density than cake batter, so the success of making a good fruit cake will rely on preventing the cake from collapsing and the fruit sinking.
Heat-treated (HT) flour is commonly used in the industry for long-life cakes that have high liquid levels. Heat treatment denatures the proteins, so reducing the gluten network formation in the batter. Normally, this is good for cakes, but less so with fruit cakes, where a small amount of gluten formation helps retain fruits in suspension.
The use of higher-protein HT flour helps with the gluten problem, but also increases water absorption in the starch component, which in turn increases batter viscosity. This helps entrap the fruit and prevents it from sinking to the bottom. Another technique that can be used is to pre-coat the dried fruits in flour before adding them to the batter. This increases the local viscosity around the fruit to deliver the same end result.
Eugenie Wiart, bakery scientist, Campden BRI
Campden BRI provides technical support to the food, drinks and allied industries worldwide. Its activities are built on a programme of industrial relevant research and innovation steered by industry. See campdenbri.co.uk or telephone 01386 842000