Changes in nitrate and nitrite content, and search for nitrosamines in storage-abused spinach and beets

Abstract

Conditions favoring formation of nitrosamines— simultaneous presence of nitrite and secondary amines at acid pH—can occur during abusive storage of comminuted fresh spinach or beets. Shredded spinach, shredded or ground fresh beets, or beet juice rapidly produced nitrite. One beet sample contained 1000 ppm of nitrite after 2 days at room temperature and still appeared edible. Shredded fresh spinach samples were considered inedible when nitrite levels of 300-500 ppm were reached. Whole fresh and all forms of processed spinach and beets accumulated little nitrite even though containing 1500-2000 ppm of nitrate originally. Selections from these tests, cooked and uncooked, and thawed, frozen, and thawed spinach were analyzed by a glc-mass spectral method for six nitrosamines (methyl-, ethyl-, and methylethylnitrosamine, nitrosopyrrolidine, nitrosomorpholine, and nitrosopiperidine). Results were negative, indicating no detectable formation of these six nitrosamines when fresh or processed spinach or beets are stored even beyond the point of edibility. © 1974, American Chemical Society. All rights reserved.