Pilot plant preparation of defatted peanuts

Abstract

Interest in defatted peanuts is due to several factors: lower calorie value; possible increase in shelf-life by minimizing oil randicity, possible use by hemophiliacs to control bleeding; and development of a new product to increase utilization of peanuts. Based on previously conducted laboratory work, pilot plant runs were conducted to prepare large amounts of materials for taste and appearance evaluation, to obtain pilot plant processing data for cost calculations, to investigate practical methods of desolventizing extracted peanuts, to develop a method for salting defatted peanuts, and to study packaging.

Fully-roasted and half-roasted batches of Virginia peanuts were extracted with hexane at room temperature for various periods of time, and oil losses determined. Fully-roasted peanuts with 81% of the oil removed had the best appearance, an acceptable taste, and require 120 hr extraction. Low rates of extraction indicate that large scale processing would be a batch method.

The extracted peanuts were desolventized for various periods of time and temperature in both forced draft and vacuum ovens. It was found that drying at a low initial temperature prior to a low initial temperature prior to a final high temperature appears to give a better tasting peanut, especially when a forced draft oven is used. Desolventizing peanuts in either a forced draft or vacuum oven requires from 9–10 hr drying time.

Defatted, desolventized peanuts were salted either by dipping in saturated salt solution at room temperature, or preferably by dipping in water and sprinkling with salt. The wet peanuts were oven dried.

Packaging of defatted peanuts (81% oil removed) in metal cans, in either vacuum or in an atmosphere of nitrogen containing less than 2% oxygen, proved satisfactory even after one year storage time. In flexible cellophane-type package, defatted peanuts tended to pick up excessive moisture within 30 days.