Effect of Freezing on Some Plant Toxins and Micronutrients in the Leaves of Amaranthus Cruentus

Abstract

Postharvest handling isone of the major factors affecting the chemical contents of vegetables afterharvesting. It is for this reason that the study was conducted to determine theinfluence of freezing on some plant toxins (cyanide, nitrate, soluble and totaloxalates) and micronutrients which include vitamins (β-carotene and vitamin C)and mineral elements (Fe, Cu, Mg, Na and K) in Amaranthus cruentus. Theresults showed that the concentrations of vitamin C, β-carotene, K, cyanide,soluble and total oxalates in Amaranthus cruentus decreasedsignificantly (p < 0.05) during one week of freezing and they remainedsignificantly unchanged in the second, third and fourth weeks of freezing. Exceptthat the concentration of β-carotene in the fourth weeks was significantlylower than the second weeks of freezing. The decreasing effect of freezing onnitrate concentration in Amaranthus cruentus was not significant duringthe first week of storage, however, its concentration decreased significantly(p < 0.05) in the second weeks and the value remained significantlyunchanged for the third and fourth weeks of freezing. The significant decreasedin the concentrations of Fe and Cu during freezing was observed during threeweeks of freezing and remained significantly unchanged in the fourth weeks of storage.Similarly the concentrations of Mg and Na in Amaranthus cruentusdecreased significantly (p < 0.05) during two weeks of freezing and remainedsignificantly unchanged in the third and fourth weeks. The results concludethat although freezing significantly reduced the antinutrients and toxicsubstances in Amaranthus cruentus it has a deleterious effects on themicronutrients content of the vegetable.