Lachrymatory Factor and Other Chemical Constituents of Some Varieties of Onion (Allium cepa L.)

Abstract

Twenty varieties of onions, five white and 15 red, were analysed for their various chemical constituents such as lachrymatory factor, colouring matter, total phenols, dry matter, carbohydrates and protein contents. The lachrymatory factor (LF) ranged from 12.50 mg/100 g to 62.25 mg/100 g on wet weight basis. The range for per cent dry matter was from 7.66 (S-71) to 16.46 (S-72). The percentage of total water soluble sugars, reducing sugars, crude protein and total phenols on dry weight basis varied from 40.0 (Punjab Selection) to 67.0 (S-72), 11.0 (S-75 and S-72) to 23.0 (S-91), 11.12 (S -51) to 22.94 (S-75) and from 1.10 (S-72) to 2.90 (Punjab Selection), respectively. The colouring matter of dehydrated onions was maximum in the Punjab Selection and minimum in S-72 and L-106. The phenolic content was higher in red than in white varieties. Varieties with a high phenolic content and lachrymatory factor content had a higher amount of colouring matter in the dehydrated onions. The variety Punjab-48 was considered to be more suitable for dehydration purposes.