After collecting and cleaning the nut from the green pericarp, the walnut is sent for drying. Drying is an important point in the processing of walnuts, the quality and, as a result, the future cost of the kernel depends on it.
You can dry the nut outdoors, indoors and in special dryers. Very small quantities of walnuts can be dried in a fruit and vegetable dryer or in an oven (at a minimum temperature of 40°C).
Drying nuts outdoors is highly dependent on weather conditions. This option is suitable for owners of small gardens and households in regions with dry warm autumn.
The walnut is spread on a waterproof fabric – oilcloth or tarpaulin, in an open area. It is better to dry the nut in the shade, because if the kernel is still milky, unripe, it will dry out when dried in the sun. The walnut is spread evenly in one layer. Several times a day, the nut must be turned over so that it dries equally from all sides. At night, it is advisable to remove the nut indoors so that dew does not spoil the whole process. On dry sunny days, drying takes 3-5 days, in unfavorable weather, the time increases to 5-12 days.
Alternatively, walnuts can be placed in a single layer on trays in stacks or on a grid (rack) at a height from the ground. Due to the air circulation between the trays and the nuts, it will take less time to dry.
The advantage of drying in the fresh air is that it does not require money for equipment and electricity, care, special knowledge and skills.
If you decide to dry walnuts indoors, you need to keep the conditions close to natural: a warm, dry place with a temperature of 27-31 ° C with good air circulation. This is important, because if the conditions are not met, the nut will dry for a long time and ultimately damp and mold.
In industrial processing of walnuts, air drying is risky and time consuming. Therefore, drying plants are used for drying: after loading the nut and turning it on, the air temperature heats up to 55 ° C, and the fans provide circulation. With a dryer, the drying time is about 1-2 days. For large quantities of nuts, a dryer is an indispensable piece of equipment. Another plus of the dryer – with it you do not depend on the weather.
Drying a walnut directly affects the quality of the kernel: if not dried, the kernel can taste bitter, damp, moldy or musty in smell and taste. If the nut is overdried, it will become brittle and it will be difficult to get a whole kernel, and this will also affect the taste and useful properties that will be lost.