Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 13, 2000
Publication Date: December 1, 2000
Interpretive Summary: Screening farmer stock peanuts prior to marketing increases the per ton value of overs lots compared to unscreened lots by removal of lower value pods and loose shelled kernels. Thus, peanut shellers must pay more per ton to purchase overs lots than unscreened lots. Improvements in peanut quality are associated with the removal of small pods and loose shelled kernels which are high risk aflatoxin components in peanut lots. Improvements are also related to changes in the shelled stock peanut outturn distribution to increases in jumbo and medium peanuts which are higher value. The hypothesis tested was whether the increased cost associated with purchasing overs lots instead of unscreened lots could be recovered with the increased shelling efficiency due to removal of high risk components and due to the increase shelled stock outturn of higher value kernels. The hypothesis was tested for the entire data set (n=394) and for integer levels of loose shelled kernels in the unscreened lots because loose shelled kernels are one of the primary determinants of farmer stock value per ton. It was found that feasibility of shellers purchasing overs lots instead of unscreened lots depended on the grade factors of farmer stock peanuts(mainly loose shelled kernels) and the ability of the sheller to recover loose shelled kernels into edible markets during the shelling process.
Technical Abstract: Mechanical screening to separate foreign material, loose shelled kernels (LSK), and smaller, lower value pods (thrus) from larger, higher value pods (overs) increased the value of lots compared to unscreened lots. The average per ton value of overs lots was $26.45 higher than unscreened peanuts, which translates into higher purchase cost to shellers when purchasing overs. The percent of LSK in unscreened peanuts was a key factor in whether shellers would prefer to purchase unscreened versus overs lots becasue as LSK increase the value per ton of FS peanuts decrease. The value of unscreened lots with 1% LSK was $5.25 per ton less (not significant) than the resulting value after screening while the value of unscreened lots with 10% LSK was $46.22 per ton less (P=0.01) than the resulting value after screening. LSK in overs lots were generally reduced to less than 1% limiting the availability of LSK for screeners to recover into edible channels. However, removal of high risk components (LSK and small kernels) should reduce aflatoxin levels in overs lots compared to unscreened lots. Significant increases in jumbo and medium outturn were associated with shelling overs lots while decreases in number 1s resulted. The difference in gross shelled stock value between overs lots and unscreened lots was increased by $29.08 per ton where no LSK recovery resulted and $9.75 per ton with full LSK recovery. The differences in returns from purchasing and shelling overs lots compared to unscreened lots were tested for different levels of LSK in unscreened lots and varying LSK recovery levels into edible channels.