Finding ways to boost the satiety - or feelings of fullness - provided by food products is a current area of interest for food manufacturers and ingredients developers. Some of the substances reputed to have satiety-inducing effects include green tea and grape seed extract. As a result, it is thought that organic acids, and in particular short-chain fatty acids like propionic acid, lactic acid and acetic acid, could be satiety triggers. The researchers, from Nizo Food Research in The Netherlands, wanted to find out if a dairy beverage containing propionic acid as a result of fermentation boosted satiety. Their study, which has been accepted for publication in the International Dairy Journal, involved 43 women aged between 20 and 40 years old, living in Ede, The Netherlands, who were healthy and had a body mass index between 20 and 25 kg/m2. What's for lunch? The women made three visits to the test centre at lunchtime, each visit one week apart. On each occasion they were given one of three beverages, called preloads. These preloads were a fermented dairy beverage, a non-fermented dairy beverage (placebo) and a non-fermented beverage with 0.6 per cent calcium propiate (positive control). They were administered in a random order in 150ml doses, and the women were simply told they were 'dairy beverages'. The women, who had all consumed a standardised breakfast at home between 0730 and 0830 but drunk only weak tea or water, were then given a 650g of pasta salad and told they could eat as much of it as they wanted.
Because of the quantity of the pasta they were given, there were always leftovers, which were then weighed. The women's short term appetite profile - that is, ratings of hunger, fullness, satiety, desire to eat, and thirst - were recorded regularly before, during and after both the preloads and the pasta lunches. Pleasantness of taste was also recorded for each of the preloads and the lunches. "A significant difference was demonstrated in perceived fullness, hunger and desire to eat between the fermented dairy beverage and the non-fermented dairy beverage," wrote the researchers. After consuming the fermented beverage the women experienced increased feelings of fullness and a decreased desire to eat. No significant differences were seen between the fermented dairy beverage and the positive control. The satiety effects were also seen to last for up to 50 minutes. Despite this, however, the varying feelings of satiety did not have an impact on how much of the pasta the women actually ate. As for the development of food concepts, the researchers said it would be worthwhile to vary the timing between the pre-load and the meal, and determine the level of propionate needed to actually have an effect on subsequent food consumption.
Senses working over time The researchers noted that, when the sensory properties of the three beverages were evaluated, the fermented beverage was said to have a pungent, sour taste that the women "did not really appreciate". The researchers said that it is difficult to speculate whether the satiating effect of propionate was either sensory or metabolic related. "To our knowledge, no observations regarding sensory satiety in relation to propionic acid have been reported," they wrote. Since no mechanism of action could be proposed, it was suggested that a follow up study be considered using more extensive measurements for satiety, such as biomarkers. Moreover, the researchers recommended that the sensory properties of the fermented dairy beverage be optimised - and perhaps a different food matrix, such as cheese, would be more appropriate and better appreciated. Source International Dairy Journal (online ahead of print) DOI: 10.1016/j.idairyj.2008.01.004
"Satiety effects of a dairy beverage fermented with propionic acid bacteria".
Authors: Rianne Ruijschop, Alexandra Boelrijk, Meike te Giffel