Comparative Studies on Nutritive and Antinutritive Composition of Onions (Allium cepa) Bulb and Leaves

Abstract

Onion (Allium cepa) is a popular food due to its typical taste and attributed medicinal importance. This paper compared the nutritional and antinutritional content of its bulbs and leaves. The proximate composition was determined through standard methods of analysis, and the amino acid profiles and the antinutrient contents were determined using the known procedures. The proximate composition (%) of the bulb and leaves, respectively, was as follows: crude protein (17.37, 3.78), fat (16.47, 3.24), ash (5.19, 11.47), crude fiber (5.31, 4.77), moisture (9.32, 3.37), and carbohydrates (46.38, 71.70). The predominant antinutrients identified included oxalate (22.14, 5.52%), alkaloids (19.71, 12.18%), flavonoids (22.11, 6.03%), and phytate (16.25 and 83.02 mg/100 g, respectively). The percentage of total essential amino acid (TEAA) values (with His) varied between 39.17% in the bulb and 48.27% in the leaves. Amino acid profiling showed that the two samples had an acidic nature. The highest concentration of essential amino acids in the bulb and the leaf samples was leucine, with 7.41 and 6.10 g/100 g crude protein, respectively. The non-essential amino acids showed glutamic acid (12.64 g/100 g crude protein) as the dominant amino acid in the bulb, while aspartic acid (5.80 g/100 g crude protein) was the highest in the leaves. These results highlight the nutritional value of Allium cepa and indicate its possible use as a dietary supplement. Proper intake of the bulbs as well as the leaves can make significant contributions towards fulfilling human nutritional and health requirements.