In recent years, world production of nuts has increased rapidly, with a greater increase on the Asian continent.
Data referring to the production year 2010.
In total, a harvest amount of 2.55 million tons of nuts was reached; China took first place with 1.06 million tons. The other nut producers, in decreasing order, were: Iran, United States, Turkey, Ukraine, Mexico, Romania, India, France and Chile. The average yield in relation to the surface was about 3 tons of fruit per hectare.
Among the various producers, the countries of Eastern Europe have proven to be those with the highest yield; according to the "Food and Agriculture Organization" (FAO), the most productive farms were located in Romania, with yields exceeding 23 tons per hectare.
The United States, on the other hand, has been declared the largest exporter; in particular, the Sacramento and San Joaquin valleys, in California, produced 99% of the national "English walnuts".
Like other nuts, walnuts must be treated and preserved correctly and zealously; otherwise, the risk is that of parasitic infestations and mold contamination. From the sanitary point of view, compared to parasitic infestation, mycoses are more harmful; this is because some strains are able to produce a carcinogen called aflatoxin . Obviously, the lots of the infected should be totally discarded and destroyed.
The ideal temperature for industrial and domestic storage of walnuts is between -3 and 0 ° C, with low humidity. However, these refrigeration technologies are not available in developing countries, where nuts are produced in large quantities; there, we mostly try to keep them below 25 ° C and reduce humidity as much as possible. Temperatures above 30 ° C with humidity above 70% can cause rapid deterioration with relative crop losses; over 75% of the humidity threshold, fungal molds are able to release aflatoxin.
Freshly picked raw walnuts with a water content of 2-8% have an optimum color, taste and nutrient density.
