Oat, guar gums and cellulose impact sweetness, flavor.

As you may know, thickeners and gelling agents modify the perception of sweetness and flavor. This is especially noticeable in gels, in which perception is often controlled by how efficiently the gel melts or breaks down in the mouth, by how flavor substances diffuse into the broken gel particles and by the evaporation of flavoring substances themselves.

In formulating food products, these activities cause problems since even slight variations in the rigidity of the gel can substantially alter the taste or flavor of a product. Unless interactions among these compounds and a thickener occur, the transfer of taste-giving substances to taste receptors and the evaporation of volatile substances during the chewing process are reduced mostly by viscosity in the mouth.

In previous studies undertaken by scientists at Finland's VTT Technical Research Center, oat gum showed interesting rheological properties, indicating its potential use as a thickener in foods. It also causes a reduction in serum cholesterol levels and has an effect on resorption of sugars. This makes it a candidate for clinical nutrition applications.

VTT Biotechnology scientists wanted to compare the effects of oat gum on the perception of sweetness and aroma along with the effects of two commonly used pseudoplastic thickeners--guar gum and carboxymethyl cellulose (CMC). They studied these compounds in model systems at two viscosity levels. The sweeteners studied were sucrose, fructose and aspartame; the flavor substances were ethyl caproate, pinene and cinnamic acid.

Researchers found that sweetness was best perceived from oat gum solutions and the least from solutions of guar gum. The effect of the composition of the thickener on the perception of sweetness was greater than that of viscosity. Reduction of sweetness by hydrocolloids was weaker for aspartame than for fructose or sucrose. In the perception of flavors both the total length of perception and the time-intensity pattern were more dependent on the model aroma substance than on the thickener. The flavoring component had more influence than the thickening agent.

So in pseudoplastic solutions, there are distinct differences between thickeners with respect to the perception of sweetness and flavor. The flavor perception from beta-glucan solutions is shorter in duration and slightly less intense than from CMC or guar gum solutions, which give nearly similar responses.

Further information. Raija-Liisa Heinio, VTT Biotechnology, PO Box 1500, FIN-02044 VTT, Tietotie 2, Espoo, Finland; phone: ?9-4561; fax: ?9-455 2103; URL: www.vtt.fi/bel.