Several organisms have been screened for their ability to produce extracellular microbial polysaccharides when lactose or glucose:galactose (1:l) were used as the carbon source during fermentation. Organisms were selected from known gum producing strains (on glucose) of Alcaligenes, Xanthomonas, Arthrobacter, Zooglea, and others. Results indicate that all organisms studied can produce polymers from hydrolyzed lactose while only Alcaligenes viscosus and Zooglea ramigera produced a gum from whey, when using conditions as reported here.
Mucilage found in hulls of yellow mustard seed was investigated. The isolated mucilage was a cold water‐swellable hydrocolloid of low to medium viscosity and exhibited thixotropic properties. Viscosity increased with addition of alkali or acid. Mucilage produced synergistic increases in viscosity when combined with guar, locust bean, or carboxymethylcellulose. Solutions were opaque, bland tasting and slightly acidic. Solutions showed stability to acidity down to pH 3.5 and also to cooking and cooling cycles. The mucilage lowered the surface tension of water and the interfacial tensions of oil and water emulsions. Emulsification was achieved in model salad dressing formulations. The mucilage exhibited excellent suspending properties.
This study compares and evaluates commercial hydrocolloids for shelf life stability in an oil/water emulsion system stored at 25°C. Observations of surface or interfacial changes and rheological parameters took place over 90 days. Parameters; n, pseudoplastic index; K, consistency index; and ro, yield stress were reported. Apparent viscosities ~0 (quality control index) and nse (oral flow index) were monitored throughout the study and correlated well with stability changes. The study produced the following results: propylene glycol alginate promotes creaminess without significant rheological contribution (Q, ~0, nso and TO). Xanthan gum contributes to body; however, oiling off was observed. Gum tragacanth and combination(xanthan, tragacanth and PGA, 1: 1: 1) act as bifunctional stabilizers, controlling both oiling off and body.
A modified GC method was utilized for the detection and quantitative determination of sugars derived from commercial gum, Agar, Carageenan, Xanthan, Gum Ghatti, Gum Arabic, Emulgum, Gum Tragacanth, and Gum Karaya. The polysaccharides were cleaved by acid hydrolysis, derivatized with "STOX" hydroxylamine to form oxime with "TM%" or HMDS +TFAA" for silylation. The separation and quantitation was performed by gas chromatography, using phenyl-B-D-glucopyranoside as the internal standard for quantitative analysis. Sugar molar ratios (percent) for all commercial gums tested were similar to literature values.
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