Abstract:

To improve cracking quality of peanuts from the western part of Sichuan province, mechanical characteristics of peanut cracking were investigated using a computer-controlled electronic tension and compression machine. A 9-run, 3-level orthogonal array design was employed to examine the effects of pressure location, loading rate and water content on peanut breaking force. The results indicated that the thickness of peanut shell was evenly distributed in different parts of peanuts. During the compression of peanut shell, three stages, i.e., elastic deformation, plastic deformation and sudden rupture occurred. The above factors significantly affected the breaking force of peanut shell. Regression equations of loading force with respect to degree of deformation of peanut shell under different compression directions were obtained through force analysis and the optimal values of the above factors for peanut cracking were determined as follows: pressure location, top surface (along the xaxis); loading rate, 30 mm/min; and water content, 15.8%.

Key words: peanut, cracking, mechanical characteristics