Submitted to: American Peanut Research and Education Society Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/16/2008
Publication Date: 7/16/2008
Citation: Dean, L.L., Davis, J.P., Hendrix, K., Debruce, M.W., Sanders, T.H. 2008. Effects of Starting Moisture on Characteristics of Oil Roasted Peanut. American Peanut Research and Education Society Proceedings.
Interpretive Summary: The amount of water in peanuts before they are roasted makes a difference in how the roasted product will taste and last in storage when peanuts are roasted in an oven. When peanuts are fried in oil or “oil roasted” , they are also affected by the water in the peanuts at the start. Photographs were taken of peanuts containing 11% moisture and 5% moisture using a Scanning Electron Microscope before and after roasting. The samples appeared to be different. The amount of oil taken up by the samples during roasting was determined by weighing the samples before and after. Coconut oil was added to peanut oil at 10% by weight. This oil mix was used to cook the peanuts of different moisture levels. Coconut oil contains the fatty acid, lauric acid which is not present in peanut oil. By measuring the amount of lauric acid in the peanuts after roasting, the amount of oil absorbed from the cooking oil was determined. The oil pressed from the peanuts was used to look for physical changes which could be related to how much oil was absorbed by the peanuts from the frying oil.
Technical Abstract: Previous research has shown that the moisture content of peanuts before dry roasting affects the quality of the finished product. This study demonstrates the effects of the starting moisture content of the raw product on peanuts that were oil roasted. Scanning Electron Microscope images taken before and after oil roasting showed distinct cellular differences between moisture levels. The amount of oil uptake was determined by gravimetric measurement. The oil exchange between the peanuts and the matrix was determined by using peanut oil containing 10% coconut oil as the roasting matrix. The coconut oil contained high levels of lauric acid that served as a marker for the oil exchange. Quantification of the fatty acids expressed from the roasted peanuts was done using profiles obtained using Gas Chromatography. Physical measurements such as interfacial tension, viscosity and density were determined for the roasting oil and the oils expressed from the roasted peanuts. The changes in the texture of the peanuts before and after roasting as a function of moisture will also be presented. These physical properties will be used to explore the oil uptake phenomena.