Sorting Peanuts by Pod Density to Improve Quality and Kernel Maturity Distribution and to Reduce Aflatoxin1

Abstract

Peanut maturity and several peanut quality factors are closely related. An examination of peanut physical properties revealed that by sorting farmer-stock peanuts into pod density classes before shelling, the maturity distributions within shelled-stock classes can be manipulated. An unsorted sample of farmer-stock peanut having an initial maturity distribution in No. 1 kernels of 66% immature, 23% mid-mature and 11% mature was sorted using a gravity separator into four pod-density fractions ranging from 98% immature and 2% mid-mature in the least dense fraction to 8% immature, 43% mid-mature and 49% mature in the most dense fraction. Along with improvements in maturity distributions, we also found that the higher test weight fractions (higher pod density) had less aflatoxin and a greater percentage of large kernels than did the low test weight fractions. Many density sorting devices were tested, including air columns, pod cleaners, and gravity tables. All of these devices were capable of sorting pods into maturity groups, but the gravity table was the most precise.