39C-20

I. M. LIMA, H. Guraya, and E. Champagne. Agricultural Research Service, U.S.D.A. - Southern Regional Research Center, 1100 Robert E. Lee Blvd, New Orleans, LA 70124

Excess weight and high cholesterol levels in blood have been recognized as major health problems due in part to consumption of more calories than are expended. The increasing concern for health goes with an increasing demand for low-fat products by the more health conscious consumer. Low-fat peanut butter products do not abound in market and quality of commercially available versions is still a concern. Peanut butter must be spreadable and not sticky and its texture is greatly affected by the particle size of the peanut flour used as a major ingredient in peanut butter manufacturing. The purpose of this study was to develop a process for making peanut flour with beneficial traits to produce high quality peanut butter having ideal particle size, oil separation and texture. A commercial peanut flour (12% fat) was mixed with water (30% w/w) and homogenized followed by drum drying using a double drum dryer. Clearance in between the drums was adjusted such that it resulted in thin dried sheets which on milling resulted in a very fine narrow single banded particle size flour. The flour was no longer gritty and it was used to dilute fat by mixing in a full fat (52.5% fat) peanut paste such that a 30% fat reduction was obtained in the peanut butter. Response surface methodology, RSM, was used to optimize drum temperature (T), drum speed (S) and drum clearance (C) in order to minimize stickiness and hardness and maximize oil separation and particle size. Based on surface responses and contour plots, optimum conditions were: T=135 °C, S=1 rpm and C=0.33 mm. Optimum values predicted by RSM for peanut flour particle size, peanut butter stickiness, hardness and oil separation were: 49.65 µm, 12347 N, 311.4 N and 6.87% respectively. Close agreement between experimental and predicted values was obtained.