36D-32 |
|
D. C. GONZALEZ, B. Mert, O. H. Campanella, and M. R. Okos. Dept. of Agricultural & Biological Engineering, Purdue Univ., 1146 Agricultural & Biological Engineering Bldg., West Lafayette, IN 47907-1146 The palatability of cereal grain foods is often increased with the addition of sugars during the cooking process. However, the role of sugars and the mechanisms in which they influence the physical and rheological properties of cereal grains after cooking and upon further processing is not well understood. Therefore, the effect of sugars on starch reassociation (e.g. retrogradation) during further processing (e.g. tempering) was investigated. Tempering was chosen because it is a common processing step used in the production of cereals from grain and it is associated with starch retrogradation. The cooking process consisted of cooking cereal grains (wheat and corn) with an amount of water 1:1 by weight in a pressure cooker. Eight grams of sucrose were added per every 100 grams of cereal grain for the cooking process. Similarly, 8 grams of High Fructose Corn Syrup (HFCS) were added for every 100 grams of grains. The effect of a combination of sucrose and HFCS was also studied (4 grams of each sugar per 100 grams of grain). A control containing no sugar was also tested. The cooked cereal grains were dried to moistures of 20% and 15%. The tempering process consisted of packing the dried grains into sealed containers and holding them for equal amounts of time until moisture was equilibrated. The rheological changes occurring during the tempering process for the cereal grains were monitored by a broad band oscillatory squeezing flow method developed in our laboratory. The method is based on the measurement of the mechanical impedance of the sample. This mechanical impedance is closely related to the sample's viscoelastic properties. Both viscous damping and elastic stiffness values increased with increasing tempering times in all cases examined. Cereal grains cooked with sugars exhibited the greatest increases in hardness supporting the role of these ingredients in promoting retrogradation.
Session 36D, Food Engineering: Rheology
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |