Abstract
Powdery white and ball-like structures are often observed on spinach leaves and are often mistaken for foreign hazardous matters by consumers. We observed and analyzed these powders. The diameter of the powder grains was about 0.1–0.2 mm, and they were attached on projections from the surface of the leaves. The powders were not solved in water, but were destroyed by chloroform/methanol. Depressed areas were observed on the ball-like shapes when dipped in ammonium sulfate solution. The water concentration was determined to be about 90%. It is considered that the white powder is composed of a lipophilic semipermeable membrane that wraps around aqueous solution. The aqueous extract of the powders contained oxalic acid, citric acid and malic acid, and a very slight amount of amino acids and free sugars.
