Blood glucose, plasma insulin and sensory responses to guar-containing wheat breads: effects of molecular weight and particle size of guar gum

Abstract

The effectiveness of guar gum in reducing post-prandial blood glucose and plasma insulin levels in human subjects seems to depend mainly on its ability to increase the viscosity of digesta in the small intestine. However, the precise relationship between the rheological properties of guar gum (either in vitro or in vivo) and the changes in blood metabolites and hormones is unknown. The aim of the present study, therefore, was to investigate the effects of wheat breads containing guar gum samples varying in molecular weight (M,) and particle size (characteristics that strongly influence the rheological properties of guar gum) on post-prandial blood glucose and plasma insulin levels in healthy subjects. The sensory qualities of breads containing guar-gum flours of different M, were also evaluated using a hedonic scoring technique. No significant differences in the post-prandial blood glucose responses were found between the control and guar breads. However, all the guar breads elicited significant (P < 0.05) decreases in the post-prandial rise in plasma insulin, an effect that did not appear to be influenced by large variations in M, or particle size of guar gum. Moreover, the sensory qualities of guar bread were markedly improved by using low M, grades of guar gum.

Effects of a beverage containing an enzymatically induced-viscosity dietary fiber, with or without fructose, on the postprandial glycemic response to a high glycemic index food in humans

“…Foodstuffs containing guar gum usually exhibit slimy mouth-feel (Williams et al, 1980), tooth packing (Tredger & Ransley, 1978), and poor palatability (Ellis et al, 1991). The overall hedonic quality of guar-containing foods can be improved by reducing the average molecular weight (ie through hydrolysis) of the galactomannan in guar gum (Ellis et al, 1991); however, this results in a concurrent loss in clinical efficacy (Jenkins et al, 1978).…”

“…The overall hedonic quality of guar-containing foods can be improved by reducing the average molecular weight (ie through hydrolysis) of the galactomannan in guar gum (Ellis et al, 1991); however, this results in a concurrent loss in clinical efficacy (Jenkins et al, 1978). Cohen et al (1980) noted that the poor palatability of guar limits its use and adds uncertainty pertaining to the degree of patient acceptance and compliance.…”

“…Although high viscosity appears to be a necessary property of fiber to maximize its benefits on blood glucose (Jenkins et al, 1978), high viscosity reduces the palatability of foods (Ellis et al, 1991), which is a major impediment to the practical use of viscous fiber. Recently, low dextrose equivalent (DE) maltodextrins were reported to prevent the dissolution of konjac flour (glucomannan) (Crosby, 2000), which should improve palatability.…”

Glycemic index in chronic disease: a review

“…The former includes the ratio of amylose to amylopectin present in the raw food (Behall et al, 1988) and the type of monosaccharide components, the amount and type of dietary fiber (Jenkins et al, 1978), the presence of large amounts of fat or protein (Nuttall et al, 1984;Wolever et al, 1985;Collier et al, 1986;Bornet et al, 1987), antinutrients such as phytic acid, lectins and tannins (Yoon et al, 1983;Thompson et al, 1984;Rea et al, 1985) and nutrient -starch interactions in carbohydrate-containing foods, such as in wheat products (Jenkins et al, 1987a). Extrusion, flaking, grinding, canning, storing and cooking of the carbohydrate-containing foods can affect the particle size and the integrity of the starch granules (Jenkins et al, 1988a) and plant cell walls (Ellis et al, 1991), making the carbohydrate portion more accessible to digestive enzymes (Wolever, 1990;Collins et al, 1981).…”

Bioavailability of starch in bread rich in amylose: metabolic responses in healthy subjects and starch structure

“…The content of resistant starch in bread products is usually very low (Englyst et al, 1992) and is related to recipe and baking conditions. The modi®cation of bread microstructure was achieved by incorporating the intact kernel or adding viscous ®bre in paste, resulting in a¯attening of postprandial glucose curves (Ellis et al, 1991;Liljeberg et al, 1992). The incorporation of intact cereal kernels (Holm & Bjo Èrck, 1992;Liljeberg et al, 1992;Holm & Bjo Èrck, 1992) or cracked kernels introduces in bread encapsulated starch.…”