Meet the Expert
Who: Jenny Arthur
What: Head of Nutrition & Product Development
Where: Leatherhead Food Research
Most UK adults eat around 18g of fibre a day, whereas the recommended average intake is 30g. With consumption of dietary fibre delivering significant health benefits, this represents a challenge to the food industry.
It’s well known that fibre aids the large intestine and bowel in the removal of waste products, helping prevent colorectal cancer by eradicating toxins. But it also supports weight management and control of sugar and fat metabolism, as well as promoting good gut health by acting as a prebiotic for the gut microbiota.
What’s more, consumer research by Leatherhead Food Research indicates widespread demand for products containing more fibre. In a survey of 1,300 UK adults, 55% said they’d like the amount of fibre in bread to increase, and 35% would like to see more in cakes and biscuits. More than 80% of respondents knew of the gut health benefits obtained from eating fibre, and most chose to eat it at breakfast. Cereals, fruit and vegetables were seen as rich sources.
Clearly there is a need for the food industry to integrate more dietary fibre into products, but there are many factors to consider. We outline three of the most pressing ones here.
1. Exploring alternative sources of fibre
In our survey, 92% of consumers had heard of wheat bran as a source of fibre, and 77% were aware of cellulose and pectin. But there is a need to educate consumers about the full spectrum of potential sources.
By-products from the manufacture of other goods, such as fruit juice, are beginning to appear on ingredients lists. For example, Kavis Mini Swiss-Rolls (sold in Europe) list apple and strawberry pomace as ingredients. Pomace is the solid residue remaining after fruits are pressed for juice or oil. It mainly comprises cell wall material of the fruit pulp.
Seeds and stems, husks and hulls as well as seaweed and algae are all emerging sources of dietary fibre. Many parts of fruits and vegetables that would usually be discarded are in fact edible and can potentially be incorporated into recipes.
2. Deploying new technologies
Developments in processing technologies are unlocking new ways to alter and improve the properties of fibres in some fruits and vegetables.
Applying ultrahigh pressure to Chinese cabbage has been shown to improve the content of soluble dietary fibre and its physicochemical and physiological properties. Blasting extrusion increases the soluble fibre content of bean dregs and acidic treatment improves the dissolution properties of citrus pectin.
Using techniques like these can boost soluble fibre or alter functional properties, such as water-holding capacity or solubility. This both enhances health benefits and the range of food-processing applications where the products can be used.
3. Overcoming technical challenges
Increasing levels of dietary fibre in products can impact on textural and sensory properties.
For instance, adding inulin fibre to bread significantly increases mixing time and affects dough properties. The stability and rise during proving and baking are also affected to varying degrees by different types of fibre. Development of gluten in wheat relies on hydration of the flour, which can be compromised if the dietary fibre competes for the water.
Addition of dietary fibre to products can also affect expansion on cooking. This relates mostly to cereals and snacks.
Solutions to these technical issues can often be found by altering the type of fibre used, or the particle size and amount of fibre added.
We expect to see growing use of dietary fibre as a key health ingredient in foods, with consumers demanding natural and tasty products that are also high in fibre. This will drive manufacturers to develop their understanding of different sources and new technologies, and the role they play in the structure and texture of various products.