A team of researchers has discovered a method to make insoluble dietary fibre in food more palatable by developing a gel coating for fibre particles. The encapsulated particles can be added to various foods and beverages, imparting a velvety texture on the tongue.
The researchers, who published their findings in the Food Hydrocolloids journal, were inspired by the natural gel-like coating that improves the texture of foods like chia seeds. The team, from the University of Copenhagen, Nestlé Research, and KU Leven used gellan gum, an approved-for-food-use biopolymer derived from bacteria, to create a gel coating for pea cell wall fibres – the dietary fibres from the structural components of pea plants.
They found that the flavourless and odourless gel-coating formed a soft barrier around the fibres, preventing direct contact between the fibres and the tongue and reducing the perception of dryness and grittiness, often associated with fibre.
Overcoming the challenges associated with added fibre in liquid applications
Professor Lilia Ahrné, one of the authors of the study, told Fi Global Insights that in principle, the method could be used in a variety of food and beverage applications, however, it holds the highest potential in liquid applications.
Ahrné explained that liquid beverages are where fibres can be more difficult to “satisfactorily add to a product”. Alongside drinks, juices, and shakes, she noted: “One could consider this application valuable in dairy products, soups, or sauces that could be enriched with insoluble dietary fibres.”
Ahrné envisions this method assisting in creating healthier foods. “We think that this technology is a virtuous example as it shows that processing can be used to create effective and efficient solutions to improve the nutritional profile of food products. We also believe that this solution is very versatile and suitable to be implemented in different products,” she explained, adding that she also sees potential to improve gut health by creating products that combine probiotics with the gel-coated fibres.
Gel-coating to increase the variety of fibre-rich products on offer
Insoluble dietary fibres, found in whole and unprocessed fruits, vegetables, and wholegrains, are a key component of a healthy diet. But in a day and age where ultra-processed foods make up the majority of people's diet – roughly 60% for US adults and 70% for children –, many people do not meet their daily fibre recommendations. Inadequate consumption has been linked to global health challenges including diabetes, heart disease, irritable bowel syndrome, breast and bowel cancer, among others.
Despite its importance in the diet, adding fibre to foods is not easy, or palatable, as it often imparts a gritty texture and dryness. Ahrné, professor at the University of Copenhagen’s Department of Food Science, explained in a press release: “If we don’t like it, we don’t eat it. It’s that simple. And no one would enjoy eating grainy flour – but that’s roughly what the sensation of insoluble dietary fibres often produces, especially added to more liquid foods like yogurt, juices, and beverages.
“This is why there is such a limited selection of fibre-rich foods and beverages. And that’s why it’s important to figure out how to incorporate fibres into more foods without causing a bad eating experience. The more variety there is in fibre-rich products, the greater the likelihood that people will increase their fibre intake. And now, we have a potential solution.”
Gel-barrier prevents contact between tongue and fibres, reducing grittiness perception
The unpleasant and poor sensory experience of insoluble fibre often discourages its consumption. The team, aiming to expand the range of food and beverage products boasting fibre, while maintaining palatability, discovered a way to encapsulate the fibres.
The team created the gel coating by encapsulating the pea cell wall fibres in a layer of gellan gum. The soft and smooth barrier formed around the fibres, preventing direct contact between the tongue and the fibres, thus reducing the perception of dryness and grittiness which is often associated with fibre.
Lead author of the study Gabriele D’Oria, former PhD student at the University of Copenhagen, explained how the gel mimics the softness of the tongue tissue: “The gel coating makes the fibres feel velvety, like cream on the tongue, where you can’t feel the individual particles because the gel prevents contact between the particles and the tongue. Since the gel is at least as soft as tongue tissue, it doesn’t trigger the sensory receptors, and we don’t perceive the gritty texture.”
Encapsulated fibre particles reduced perception of grittiness and mouth dryness
During lab trials, D’Oria explained that it took her seven minutes to produce thousands of gel-coated fibre particles. Of the fibre particles, the team successfully encapsulated 95% of them. “[...] This can definitely be upscaled once operating on a larger scale. One could imagine giant silos producing tonnes of coated fibre particles,” she added.
In addition to lab trials, the team tested palpability with a trained tasting panel. Test subjects were given samples of both gel-coated and uncoated pea fibres, both dispersed in water. Subjects were instructed to rate and assess each sample on specific sensory attributes, including number of perceived particles, grittiness and dryness in the mouth.
The researchers found that subjects perceived an approximate 52% reduction in perceived particles for the gel-coated fibres, a 42% reduction in grittiness and a 36% reduction in mouth dryness compared to the uncoated pea fibres.
While the samples were dispersed in water, Ahrné told Fi Global Insights the team believes the technique may work for highly acidic drinks too. She explained that previous studies have shown that gel made from low acyl gellan gum increases in strength as the acidity rises, specifically around a pH of 3.5 or lower. She added that instability in the gel could happen in acidic conditions and would need to be tested.
Potential applications: From fussy children to active individuals and elderly populations
While the team argued the encapsulated fibres could be valuable additions in beverages, dairy products, soups, sauces and even combined with the probiotics, they also see the potential for the method to be used in foods for specific populations, including children, older adults, and active people.
Ahrné said: “We think that this method could be beneficial for the elderly population which needs insoluble fibers to improve the gut health […]. Furthermore, fluid gels are very suitable also for people suffering from swallowing conditions like dysphagia which can occur with ageing or after a stroke.”
When it comes to active populations, Ahrné explained that active populations are very aware of their nutrition. “Therefore, developing formulations for this group rich in insoluble dietary fibers might represent an interesting marketing opportunity which now remains hindered by the negative insoluble dietary fiber oral perception,” she added.
For children, Ahrné noted it might be beneficial to apply the coating strategy to develop appealing products enriched in insoluble dietary fibers that would not trigger rejection due to the more appealing texture.
In a similar vein, at Fi Europe, Emma Schofield, associate director of global food science at Mintel, a market intelligence agency, spoke about the opportunities available for brands to develop more nutritious ultra-processed food (UPF) formulas. One suggestion Schofield put forward was to “put missing nutrients back” into these UPF products, which could encompass the addition of gel-coated fibre particles, boosting the nutrient profile of a UPF and addressing health concerns from consumers, without comprising taste or texture.
Read more about:
Europe
