Sweet potato curing cabinet

Overview

A sweet potato curing cabinet is a small, closed enclosure in which freshly harvested roots are held warm and humid for about a week. Curing lets the skin tighten and lets abrasions and cuts heal over before the roots go into storage.

Curing is not the same as storage. Curing uses high heat and high humidity to heal wounds; storage uses cooler and drier conditions to hold the crop. The same enclosure is not used for both.

Curing conditions

The North Carolina Cooperative Extension target is about 29 °C (85 °F) with 85 to 95% relative humidity for five to seven days, followed by storage at about 13 to 18 °C (55 to 65 °F). Iowa State advises 27 to 29 °C (80 to 85 °F) and 90 to 95% humidity for a week. Washington State gives 27 to 32 °C (80 to 90 °F) and 80 to 90% humidity. Delaware gives 29 °C (85 °F) and 90% humidity for five to seven days.

The extension targets agree on warmth and high humidity for about a week. They differ within a few degrees and several percentage points, so the cabinet should be built to hold a chosen point rather than one fixed value.

Wound healing

Curing works by letting wounds heal, so the cabinet's job is to keep the surface moist enough for healing but not wet enough to rot. A UK-published study reports that drying out tissue blocks inhibits wound healing, and that under moderate humidity sweet potatoes did not always finish healing.

The NC State study of 1974 found that extreme temperatures, 4.5 °C and 45 °C, slowed healing in every cultivar it tested. That supports holding the cabinet near the mid-warm band rather than running it hot to save time.

Design and comparison

The programme brief compares three forms: a passive baseline under plastic, an active controlled cabinet, and a commercial alternative. A cleanable insulated enclosure with vented crates is the design it proposes. Crates keep the roots off the floor and let air circulate, and a fan with a humidifier and heater gives control.

A passive plastic-tented enclosure is cheaper and needs no power, but it cannot be tuned to a target. An active cabinet can be set and logged, at the cost of electrical work and cleaning. No inspected source measures energy use for a small cabinet, so that comparison must be made by testing.

Monitoring

Record the cultivar, the harvest damage and the actual root temperature for each batch. Map temperature and humidity at more than one point, because moisture and air movement vary inside a small box. Condensation on the lid and walls is a sign that ventilation or temperature needs adjusting.