Production and utilisation of gastric rafts from polysaccharide combinations to induce satiety: a preliminary study

Purpose - The purpose of this paper is to prepare alginate-pectin-starch containing matrices expanded by the generation of carbon dioxide, from carbonates when in contact with acids, characterise their structure in vitro and to assess their capacity to provide satiety in vivo. Design/methodology/approach - For in vitro characterisation, carbon dioxide expanded polysaccharide matrices (rafts) were prepared in HCl and their structural strength was measured in terms of their capacity to resist breakage in a model test system. For in vivo trials, 12 healthy volunteers (mixed sex, aged 25-55) were recruited to take part in the three-part trial. Each part lasted for one week where volunteers consumed polysaccharides (in 50 ml water) with or without rafting salts (carbonates), or water (as a control). Effects on satiety, reduction of food intake and any change to body weight were evaluated with the volunteers. Findings - The in vitro results showed that aqueous solution/dispersions (50 ml) of alginate-pectin-starch matrices produced rafts in hydrochloric acid (pH < 2), where increasing the ratio of carbonates to polysaccharides (range from 0.25:1 to 1.5:1, w/w) provided increased floatation capability but reducing gel strength. These rafts were stable for over 24 h at room temperature within 0.05-0.5 M HCl. For in vivo "satiety" studies, when volunteers consumed (daily) aliquots of the polysaccharide mixture plus flavour and sweetener without carbonates 2.5 h after lunch, they felt the onset of hunger on average 186 ± 68 min after consumption of the polysaccharides. This was not significantly different from a water only control (onset of hunger at 165 ± 47 min). When polysaccharides plus flavour sweetener and carbonates were consumed, however, volunteers reported feeling the onset of hunger at 224 ± 62 min on average after consumption which was significantly different from the water control (p < 0.001), or the polysaccharides without carbonates (p < 0.01). When consuming the polysaccharide rafting format, half of the volunteers reported a reduction in size of their evening meal. Originality/value - These data indicate that the alginate-pectin-starch combination with carbonate salts in a "gastric rafting format" provide a potential approach in the management of body weight and obesity.