IT IS ALMOST PECAN HARVEST TIME: HOW SHOULD YOU STORE THEM?

IT IS ALMOST PECAN HARVEST TIME: HOW SHOULD YOU STORE THEM? Pecan nuts harvested in the fall can retain their fresh condition during the next year or until consumed, if handled and stored properly. Good storage helps maintain the pecan’s quality. A good quality kernel is about 73–75% oil, 12–15% carbohydrates, 9–10% proteins, 3 to 4% water, and about 1.5% minerals. A high percentage of oil is indicated by plumpness, crispness, and solidity of kernels, compared with shriveling, sponginess, and hollowness. The high oil content of Pecans and the fact that it is highly unsaturated (93%), or cholesterol free, is one of the most important factors, along with water and temperature, impacting the storability of pecans. Because of the high oil content, rancidity can develop at warm temperatures and is more noticeable than in most other nuts. Pecan oil is 95% or more oleic and linoleic oils. Both the amount of oil and degree of saturation vary with geographical locations. Linoleic acid is the primary chemical component responsible for oxidation and rancidity in pecan kernels. Linoleic acid varies widely in different varieties of well matured and plump kernels, and it also varies from year to year in the same variety. From personal experience don’t make pie for poorly stored Pecans. Lowering the moisture content of pecan kernels is an important step for maximum storage life of pecans. Pecans are often harvested at moisture contents higher than desirable for storage. Pecans harvested early can contain 25–30% moisture which decreases when harvested latter. The ideal storage moisture for pecans is about 4% so lowering the moisture as soon as practical after harvesting is best. This prevents molding, discoloration, and breakdown of the oil. Shelled pecans stored at non-freezing temperatures should be maintained in an atmosphere of about 65–70% relative humidity to hold the 3–4% moisture content. Humidity above these values can cause kernel molding and pecan texture deterioration (pecans become soft and rubber-like), whereas lower humilities will cause excessive drying. In-shell pecan kernels will darken under high humidity as a result of the tannic acid being dissolved from the shell lining. For vacuum or gas packed pecans, or those stored under freezing conditions, relative humidity control is not necessary. Lower temperatures usually result in longer storage life of nuts. Pecan pieces have a shorter shelf-life than pecan halves. This time reduction is the result of more surface exposure of the pieces. Storage of nutmeat pieces should be limited to 1 or 2 months at temperatures about 32°F. The greatest benefit of storing at low temperature is retention of fresh flavor, followed by color, aroma and texture. Because pecan meats absorb odors and flavors readily from the surroundings, a storage area free of odoriferous materials and commodities is necessary. In-shell pecans can remain good for 4 months at 70°F, but can be stored successfully for 18 months at 32°F to 36°F. Storage life of in-shell nuts may extend to 5 years or more when stored at 0°F. An unbroken pecan shell is one of the best packages for kernels. But, an oil film will form from the broken areas of shelled pecans and spread over the kernels as rancidity develops. When taking nuts out of frozen storage, thaw kernels slowly; this is called tempering and involves gradually raising the temperature to 45°F or 50°F before exposing to a higher temperature. If the pecans are subjected to unusually high temperatures upon removal from storage, moisture will condense on the kernels. Therefore, a series of gradually increasing temperatures is desirable. The package for shelled pecans must be impermeable to oil. At home, pecan kernels may be kept in the refrigerator in a covered glass jar or in plastic bags. In-shell pecans can be stored at room temperature for a short period of time. Keep in a refrigerator, if so desired, to keep for longer than 4 months. Eddy County Extension Service, New Mexico State University is an equal opportunity/affirmative action employer and educator. All programs are available to everyone regardless of race, color, religion, sex, age, handicap, or national origin. New Mexico State University, U.S. Department of Agriculture, and the Eddy County Government Cooperating.