Mo. Abukutsa et al., EFFECT OF NITROGEN-SOURCES AND STORAGE ON THIOCYANATE CONTENT OF KALE(BRASSICA-OLERACEA VAR ACEPHALA) LEAVES, Discovery and innovation, 5(4), 1993, pp. 367-371
Thiocyanate content of kale leaves reduces its nutritional value and p
oses a risk to human health. In order to study this phenomena two expe
riments were conducted at Kabete field station, University of Nairobi.
The experiments considered the effect of nitrogen sources and leaf st
orage conditions on thiocyanate ion content in leaves of thousand-head
ed kale (Brassica oleracea var. Acephala D.C.). Two nitrogen sources:
calcium ammonium nitrate (CAN) and sulphate of ammonia (SA) at the rat
e of 20g N per plant were used. Leaves were harvested and stored under
three different conditions: shelf storage; storage with petioles imme
rsed in water; and refrigeration at 6+/-2-degrees-C. Leaves were analy
sed for thiocyanate at harvest and after storage of two, four and six
days. Leaves from plants top-dressed with sulphate of ammonia had sign
ificantly higher thiocyanate content than those from plants top-dresse
d with calcium ammonium nitrate. Leaves stored on the shelf contained
lower levels of thiocyanate than those stored in the refrigerator. Thi
ocyanate content of leaves decreases with increasing storage time, the
decrease being greatest in leaves stored on the shelf and smallest in
those stored in the refrigerator. Top-dressing with calcium ammonium
nitrate and storing leaves on the shelf for six days decreased thiocya
nate content in the leaves.