29C-8 |
Employing rheological techniques to examine the stability of peanut butter as affected by stabilizer concentration |
V. M. TOTLANI, Dept. of Food Science & Technology, Univ. of Georgia, 1109 Experiment St., Melton Bldg., Griffin, GA 30223-1797 and M. S. Chinnan, Department of Food Science and Technology, University of Georgia, 1109 Experiment St., Melton Bldg., Griffin, GA 30223-1797. Peanut butter exhibits viscoelastic nature with the addition of a stabilizer. It forms a weak gel network that prevents oil separation and provides a smooth texture to the product. Hence, an evaluation of its viscoelastic properties may provide information regarding the network formation, and the factors influencing its strength. Study the effect of stabilizer concentration and storage on network strength of peanut butter. Laboratory prepared peanut butter samples (0.0-2.0% stabilizer concentration) were divided into two sets: 1) Fresh samples for evaluation at 0, 24 and 48 h of preparation; 2) Stored samples for analysis at 15 d intervals during extended storage of 3 months, at 35 ºC. Rheological analysis was done using Advanced Rheometer (AR1000, TA Instruments) with 40mm parallel plate geometry and gap setting of 1000 or 2000 µm. Oscillatory time sweeps (0.01% strain), oscillatory stress sweeps (1-200 Pa) and creep recovery tests (1 Pa, 5 min) were done with samples at 26 ºC. In time sweep tests, increase in the stabilizer concentration caused the elastic component to remain predominant in terms of the storage modulus values of G¢0.0< G¢0.5< G¢1.0< G¢1.5< G¢2.0 for fresh and G¢0.0 > G¢2.0 > G¢1.5 > G¢1.0 > G¢0.5 for stored samples; where G¢z represents the storage modulus at stabilizer level z. Oscillatory stress sweeps could detect the LVR (linear viscoelastic range) for various levels of stabilizer concentration for fresh (only at 2%) and stored samples (at 0.0, 1.5 and 2.0%). The viscoelastic behavior in creep recovery tests was explained by the presence of three retardation elastic compliances. Ability to trace the formation and deterioration of network structure successfully in peanut butter during the 48 h tempering and storage period can lead to a rapid testing method of predicting its long-term stability.
Session 29C, Food Engineering: Rheology and texture
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