A Response Surface Study of Extruded Corn Starch/Skim Milk Powder Blends

Skim milk was ultrafiltered to three lactose/protein ratios and spray dried. The skim milk powder was extruded with pearled corn starch at different moisture contents, protein contents, lactose/protein ratios, and feed rates (control variables). Response surface methodology and a central composite in cube experimental design were used. This design required 30 experimental runs with 16 factorial points, 8 axial points, and 6 center points for replication. The physical and functional properties evaluated were expansion ratio, product temperature, bulk density, color, shear stress, viscosity, and water absorption index (response variables). Scanning electron microscopy was done to evaluate the microstructural attributes of the extrudates. A quadratic model was used to express the response variables in terms of the control variables. Response surfaces were generated by assigning center point values to 2 of the 4 control variables and then solving the fitted equations as a quadratic in the remaining 2 control variables. An increase in moisture content decreased expansion ratio, product temperature, color, and water absorption index, and increased bulk density, shear stress, and viscosity. An increase in protein content decreased product temperature, shear stress, viscosity, and water absorption index, increased color, and had no effect on expansion ratio and bulk density. An increase in lactose/protein ratio decreased product temperature, viscosity, and water absorption index, and had no effect on expansion ratio, bulk density, color, and shear stress. Feed rate did not have significant individual effect on any response variable. Expansion ratio had a negative correlation with bulk density (r = -0.61) and shear stress (r = -0.62) and a positive correlation with product temperature (r = 0.52). Bulk density and shear stress were positively correlated (r = 0.69), and product temperature and water absorption index were positively correlated too (r = 0.81). Expansion ratio, bulk density, color, and shear stress were chosen to determine a combined set of extrusion conditions most likely to produce an extrudate with properties suitable for a snack-type product

UNUSAUAL PRESENTATION OF SUBMANDIBULAR DUCT AND GLAND CALCUI: CASE REPORT

Sialolithiasis is one of the most common pathologies of the submandibular gland; sialoliths account for about 80 percent of all salivary duct calculi.The majority of sialolith occurs in the submandibular gland or its duct and is common cause of acute and chronic infection. Salivary stones larger than 15 mm are classified as giant sialoliths. They are uncommon in the practice of otolaryngology, and their management has always been a therapeutic challenge. This report presents the two unusual and rare cases of large sialolith of the submandibular duct as well as gland measuring 70x11mm and 54x25mm respectively.