Cold Storage and Tempering of Shelled Peanut1

Abstract

The fiberboard box (121×102×124 cm) used to transport and store shelled stock peanuts was compared with an unvented and vented plastic box (121×121×124 cm) for potential condensation during cooling in cold storage (2.5 C and 72% RH) and tempering (20 ± 5 C and 72 ± 20% RH) after removal from cold storage. The boxes held 1000 kg of shelled runner peanuts at about 6.3% w.b. moisture content. In cold storage, the time required for the temperature to change 50% (t50) was 87 and 63% for unvented and vented plastic boxes of the t50 of the fiberboard box, respectively. In the tempering phase, the center peanut temperature began to change after 50 hr in the fiberboard box compared to 19 hr in the vented plastic box. During tempering, the t50 for the unvented and vented plastic boxes were 63 and 36% compared to the fiberboard box. The temperatures in the vented plastic box responded faster to the surrounding conditions and the time for potential condensation to occur in the peanuts was less. These results suggest that a temperature-controlled area for tempering may be needed if the difference between the cold storage and tempering area temperatures is greater than 15 C.