30A-1 |
The roles of rheological properties on stability of citrus drink emulsions in the absence of weighting agents |
A. R. TAHERIAN1, P. Fustier1, and S. Tajchakavit2. (1) Food Research and Development Center, Agriculture and Agri-Food Canada, 3600 Casavant Blvd. west, St-Hyacinthe, QC J2S 8E3, Canada, (2) A. Lassonde Inc., 170 Fifth Ave., Rougemont, QC J0L 1M0, Canada Gums are water-soluble biopolymers consisting of high molecular weight polysaccharides known as emulsifiers, stabilizers and viscosity builders for citrus drink emulsions. Several hydrocolloids such as gum arabic, modified starches, xanthan gum, propylene glycol alginate and guar gum have been mentioned as food additives having special functions such as: ‘‘retardation of creaming and sedimentation of oil droplets in citrus drink emulsions’’. The role of rheological properties linked with these gums as either emulsifiers or stabilizers in citrus drink emulsions remained somewhat obscure. The aim of this study was to highlight those rheological properties associated with stability of citrus drink emulsions as a function of both emulsifiers and stabilizers gums and at the absence of weighting agents. Citrus drink emulsions were prepared using gum arabic and two types of modified starches (Purity Gum Be and Purity Gum 2000) as emulsifier gums at two different concentrations. A constant amount of vegetable oil was added to each gum solution and followed by addition of even amounts of xanthan gum or xanthan and PGA gums or xanthan, PGA and guar gums as stabilizers. Flow and elastic properties of each prepared emulsion was examined using TA-Rheologist Instrument equipped with a 60 mm and 2° cone. After diluting of emulsions in acidified sugar solution the rate of creaming and sedimentation were tested by quantity (QuickScan Instrument) and by quality (stability in glass bottle). Results indicated that, in addition of viscosity, pseudoplasticity and elasticity of emulsions play a great role in stability of citrus drink emulsions. Elasticity of emulsion was related to the pseudoplasticity and the more elastic emulsion was more pseudoplastic and hence more stable. Emulsion prepared with Purity Gum Be, xanthan, PGA and guar gums designated the greatest pseudoplasticity, elasticity and stability among the other emulsions.
Session 30A, Citrus
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