Effect of Maturity Stages and Drying Methods on the Retention of Selected Nutrients and Phytochemicals in Bitter Melon (Momordica charantia) Leaf

Abstract

The purpose of this study was to investigate the nutrient and phytochemical composition of bitter melon leaves under varying maturity levels and drying techniques. Fresh, oven-dried, and freeze-dried leaves were evaluated over 3 maturity stages. In fresh leaves at various stages, crude fat, crude protein, and soluble dietary fiber contents ranged from 4.2% to 13.6%, 6.4% to 23.1%, and 0.04% to 3.50% on dry-weight basis, respectively. The contents of K, Ca, Mg, Fe, and Zn ranged from 1850.8 to 2811.8, 837.4 to 4978.2, 317.3 to 512.4, 8.4 to 16.7, and 4.1 to 5.9 mg/100 g dry-weight basis, respectively. Vitamin C, beta-carotene, and lutein contents ranged from 397.4 to 1275.1, 154.2 to 422.8, and 737.6 to 1304.6 microg/g dry-weight basis. The major flavonoids and phenolic acids were rutin, gentistic acid, and o-coumaric acid, which ranged from 7.57 to 12.75, 2.53 to 10.11, and 4.24 to 9.75 mg/g dry-weight basis, respectively. In oven-dried samples, 40.2% to 52.3% of vitamin C, 35.4% to 55.4% of beta-carotene, 25.6% to 71.6% of lutein, 26.4% to 84.0% of rutin, trace to 11.4% of gentistic acid, and 7.4% to 46.6% of o-coumaric acid were retained, while the retainment ratios of these components in freeze-dried samples were 84.7% to 99.0%, 76.4% to 99.3%, 90.4% to 96.1%, 39.8% to 99.3%, 24.1% to 68.4%, and 75.8% to 87.0%, respectively. The data showed that freeze-drying better preserves the nutrient and phytochemical quality of bitter melon leaves in comparison to oven-drying. Bitter melon leaf is a rich source of selected nutrients and phytochemicals.

Biological Activities and Effects of Food Processing on Flavonoids as Phenolic Antioxidants

“…Freeze-drying is the less aggressive method whereas hot air drying leads to major losses. As intermediate solutions microwave and vacuum drying can be used (Dong et al, 2011;Viña & Chaves, 2008;Zainol et al, 2009;Zhang et al, 2009 A few studies identified phenolic compounds in foods and followed their degradation during heat treatment. They noticed that individual phenolic compounds are also subject to heat degradation.…”

Kinetic Stability of Lutein in Freeze-Dried Sweet Corn Powder Stored under Different Conditions

“…Freezedrying process of sweet corn is used to increase its shelf life with a minimal loss of nutrients, which may be a promising technique to avoid amounts of lutein decreased via heat degradation, several researchers have analyzed nutrient content in freeze-dried plant materials (Siriamornpun et al, 2012;Zhang et al, 2009;Kao et al, 2011), however few reports have evaluated the lutein content in processed corn under different storage conditions. Naturally, lutein is usually present in their all-transconfiguration, except for processing of food such as drying, heating, and cooking that affecting all-trans-lutein partially converted into their cis-isomers (Bengtsson et al, 2008; AparicioRuiz et al, 2011;Kao et al, 2012).…”

Bioactive properties and phenolic profile of Momordica charantia L. medicinal plant growing wild in Trinidad and Tobago

“…leaves (Madala et al, 2016). From the flavonoids identified in this study, rutin (compound 6) was previously observed in M. charantia fresh leaves (Zhang et al, 2009) and fruits (Kenny et al, 2013). The presence of aglycon isorhamnetin was confirmed in M. charantia fruit by Lako et al (2007).…”