ホウレンソウ葉表面に付着する白色顆粒(普及・教育・利用)  [in Japanese] White Powder Attached to the Leaves of Spinach(Human Issues & Methodology in Horticulture)  [in Japanese]

ホウレンソウの葉の表面に白色で球状の穎粒が頻繁に観察される.異物ではないかとの消費者の疑問に答えるため,解析を行った.本頼粒の直径は0.1〜0.2mm程度であり,葉の表面から出た突起に接続していた.白色穎粒は水には溶けず,クロロフォルム/メタノールで破壊された.硫酸アンモニウム溶液中で球にくぼみが観察された.水分は約90%含まれていた.このことから,本穎粒は,脂溶性の半透膜中に水溶液が閉じこめられたものと推定できる.本顆粒の水抽出液を分析した結果,遊離糖は含まれず,シュウ酸,クエン酸,リンゴ酸を含んでいた.

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 0.1-0.2mm, 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.