Reducing sugar with extruded flour
Michael Adams - May 2020
When did you last consume some sugar? Chances are it was probably today. It’s a difficult ingredient to
avoid, and yet it’s associated with so many negative health issues. From obesity to tooth decay,
consumers are beginning to avoid sugar or seek low-sugar ingredients. Food manufacturers are responding by reformulating and developing products with less sugar, further encouraged by voluntary targets set by Public Health England in 2017 that urge them to reduce 20% of the sugar in their products - including biscuits, cakes, sweet confectioneries and breakfast cereals - by 2020.
Easier said than done
Besides sweetness, sugar contributes to many of the quality characteristics of baked products: the
caramelisation that produces the desirable golden-brown colour, structure formation and the soft textures
created by sugar’s ability to bind water. So, if you reduce the sugar, an alternative ingredient is often needed to mimic one of these characteristics. You could potentially add many ingredients, but where do you draw the line? Let’s face it, consumers do not want to see an ingredients list longer than the packaging itself.
So, what’s the solution?
Extrusion is a pre-processing technique that can be used to optimise the nutritional value and
techno-functionality of an ingredient. How does it work? Put simply, the extrusion process involves
feeding a product through a rotating screw that subjects it to high shear. This increases pressure and temperature which, for wheat flour, leads to starch breakdown and protein denaturation; for consumers, it makes the flour easier to digest. There’s also something for the bakers: the extruded flour’s starch gelatinises which makes it adopt the water-binding properties that we usually rely on sugar to provide.
So, can you reformulate a product with extruded flour to ensure it behaves the same even when its sugar
is reduced? In theory, yes, but what about in practice?
As part of our research into pre-processing for improved nutrition, we replaced 10% of a cake’s plain
flour with extruded flour and reduced the sugar content by 20%. The result? According to a panel of
sensory assessors, the cake maintained its appearance and firmness but, as you’d expect, it didn’t taste as sweet as the control cake. However, the panel did comment that the reformulated cake was “still acceptable” as it had, “a very nice crumb, appealing creamy colour and a good flavour.” After undergoing the extrusion process, we found the flour to produce caramelised notes that contributed to the cake’s flavour and masked the lower sweetness.
So, a palatable cake which looks almost identical to the control and achieves PHE’s 20% sugar reduction target - sounds like a good starting point for producing clean label products, but what are the challenges?
In cake, sugar plays a key role in lengthening shelf-life by reducing water activity which hinders the
growth of microorganisms. Our bakery scientists found that their reformulated cake had a higher water
activity than the control. This creates concern over a potentially shorter shelf-life, a factor that food manufacturers must consider when using extruded flour in their products.
Next, we will determine the impact of extruded flour in other bakery products such as wraps and bread. Flour is also used as a key ingredient in soups and in sauces as a bulking agent, or to achieve a specific viscosity, so next we will be looking at how extruded flour behaves in these applications.
About Mike Adams
Mike is the Process Innovation Lead, within the Consulting, Technology Group at Campden BRI and joined the organisation in April 2016.