Unilever has achieved “very exciting results” using alginate - a gelling agent derived from seaweed - in meal replacement drinks to boost satiety, but is struggling with it in commercial formulations, scientists have admitted.
Dr Hanny Boers, who is based at Unilever’s research and development head office in Vlaardingen, said: “We have conducted several human intervention trials looking at maximising satiety from SlimFast-style meal replacement shakes by using alginate.”
Boers, who was speaking at a Leatherhead Food International conference on dietary fibres last week, said the best results were achieved with high gelling alginate, which significantly boosted satiety and delayed gastric emptying, as it literally swelled in the acidic environment of the stomach and filled people up. Very viscous (high molecular weight) guar also performed well.
Encouragingly, significant results could also be achieved using relatively small quantities of alginate (0.8%), she said. “These are very exciting results.” However, Unilever was not yet at the stage where it could translate these learnings into commercially viable products, she said.
“The big challenge is preventing the alginate from swelling before it hits the stomach. The problem we have is that we add lots of vitamins and minerals such as calcium to the shakes because they are meal replacements, and as soon as you do that, the alginate starts gelling, which means the drinks are far too thick and gloopy by the end of the shelf-life.”
Alginates are used industrially for their ability to retain water and for their gelling, viscosifying, and stabilising properties. But they also form gels in the presence of calcium, she explained. Ideally, the alginates would only swell and form lumps once they hit the low pH environment of the stomach, she said.
Volunteers in the studies were asked at regular intervals how hungry they felt with results marked using VAS (visual analogue scale) scores, while MRI scans showed what the drink was doing in their stomachs and how long it stayed there, she said.
While hormones associated with appetite regulation such as ghrelin, GLP-1, CCK and PYY could also be monitored via blood tests in satiety testing, VAS testing was more useful given that there was not always a clear correlation between hunger, food intake and satiety hormones, she argued.
The most popular options for product developers looking to develop more satiating, but less energy-dense products, are fibres (oligofructose, inulin, guar gum, polydextrose, corn etc), proteins (soy, whey, milk, pea, potato), or combinations of the two - as used in Kellogg’s Special K Sustain cereal or Danone’s Shape ‘Feel Fuller for Longer’ yoghurts.
However, regulators would be unwise to approve generic health claims about proteins or fibres and satiety, she cautioned.
While Unilever itself has launched weight management products based on proteins and fibres such as SlimFast Hunger Shots, these are backed by scientific studies on the specific proteins and fibres in question, added Unilever senior scientist Dr David Mela.
“The effects of these ingredients are highly dependent on the level and exact specification of the fibres and proteins and the food matrix of the product you’re putting them into. Not all fibres in particular are the same. I would therefore hope and expect the European Food Safety Authority to exercise real caution in this area as it assesses applications from industry under the Nutrition and Health Claims Regulation.”