36D-11 |
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A. Ritter, J. L. Briggs, P. Maguire, and A. H. BARRETT. U.S. Army Natick Soldier Center, U.S. Army Research, Development and Engineering Command, Combat Feeding Innovative Science Team, Kansas St., Bldg. 36, Rm. E-108, Natick, MA 01760-5018 The US Army is developing high-carbohydrate (energy enhancing), easily-consumed gel products. There is a desire to further fortify these ration items with lipids in order to increase caloric density, without compromising texture and stability. The objective was to determine the effect of oil concentration on rheological and other physical properties of the gels, and to determine the maximum feasible amount of oil that could be added to fortify the gels. The formulation for an orange-flavor gel thickened by konjac, gellan, and xanthan gums was varied so that samples containing 0, 2, 4, 6, 8, 10, 12, and 16% added canola oil (by weight) were obtained. The gels were analyzed by rotational viscometry at temperatures from 30oC to 80oC and fitted to Bingham and power law flow models. Effects of oil content on gel color and extent of syneresis was also determined. Furthermore, the effect of 4 weeks storage at 49o C on flow parameters was also assessed. Multivariate regression was used to determine the significance of oil concentration and storage on gel properties. Results showed that both initial yield stress and initial flow coefficient increased with increasing oil content. The gels also became less shear-thinning with increasing oil content. Increasing temperature reduced the magnitudes of all rheological parameters, with a significant interaction between oil concentration and temperature for the Bingham coefficient. There was no significant effect of storage on flow properties. Oil separation was minimal up to 8% added oil, but noticeable beyond that concentration. Oil content had an insignificant effect on gel color. Performance gels can be formulated with up to 8% added oil with little effect on flowability or syneresis.
Session 36D, Food Engineering: Rheology
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |