| Popis: |
A study was carried out to determine the influence of mucilage viscosity on the globule structure (i.e. size and number) of certain starch emulsions. The starches investigated were cassava, potato and maize. The emulsions were prepared by mixing the starch mucilage of a predetermined concentration 4%w/v with arachis oil in the ratio 50:50, using a silverson mixer fitted with a dispersator head. The emulsions were stored at room temperature (28±20C) for 7 days. Changes in globule size were monitored by photomicroscopy. Viscosities of the mucilage and those of resulting emulsions were determined using a capillary flow method. The viscosities of the emulsions expressed as time of flow (seconds), were 680 (cassava starch), 369 (potato starch) and 270 (Maize starch), and for the mucilage 510 (cassava), 336 (potato) and 248 (maize). The corresponding mean globule sizes of the fresh emulsions were (µm) 28±6, 42±6 and 45±5 respectively. The increase in globule size during storage (measure of globule coalescence rate) was 1.8±0.2µm day -1 (cassava), 3.5±0.2µm day -1 (potato) and 4.6±0.3µm day -1 (maize). Thus, a higher viscosity of the dispersion medium is associated with the production of finer and more stable emulsions. |
