Effect of household processing on nutritional and antinutritional composition, mineral-mineral ratios, and functional properties of Colocasia leaves

Colocasia leaves are high in nutrients and other phytochemicals but their utilization remains limited due to a lack of awareness. Higher content of anti-nutritional factors like oxalic and tannic acid in Colocasia leaves limit nutrient availability. In the present study, the effect of four household procedures viz. soaking (8–12 h), microwave heating (2–6 min), cooking (30–60 min), and blanching (1–3 min), followed by sun drying, was studied on the nutritional, antinutritional and functional properties of Colocasia leaves. A significant increase in crude fibre (25.7%–29.65%), and protein (4.33–15.6%) content was found in all the treatments except for the microwave treatment. A significant decrease in fat (5.7–31.4%), ash (20.34–28.22%), oxalic acid (27.07–35.32%), and tannic acid (up to 96%) was also found in various treatments. Among the minerals, a significant increase was reported for calcium (up to 16.38%), and iron (up to 5.9%). The highest mineral retention was found in soaked samples. The soaked and cooked samples also had a higher Ca: Mg ratio. A significant change in functional properties was also found. FTIR peaks suggested no significant qualitative effect occurred on phytochemical or physicochemical characteristics. Cluster analysis showed that cooking was second to soaking in terms of overall quality which were most comparable to the control. Cooking efficiently reduced the antinutritional factors, however, a significant loss of nutrients and functional properties was also observed. Therefore, the soaking of Colocasia leaves for 8–10 h is recommended as the best practice before their food applications.