Effects of processing methods on the proximate composition and momordicosides K and L content of bitter melon vegetable

Bitter melon (Mormodica charantia L.) has been associated with health benefits such as hypoglycemic, antiatherogenic, and anti-HIV activities. The vegetable, however, has an unpleasant bitter taste. The purpose of this research was to establish the effect of various processing methods on the moisture, lipid, and protein content of the Sri Lanka variety of bitter melon and to determine the effect of the processing methods on momordicosides K and L contents. The processing methods used were frying, blanching, sun drying, oven drying, freeze drying, and bitter masking with five different commercial bitter masking agents. Moisture, lipid, and protein analyses were done using standard AACC methods. Drying decreased moisture content from 92% to 9.5-10.2%. Frying lowered moisture content to 0.8% while increasing lipid content from 3.6 to 67%. Protein content remained unaffected by treatments. A liquid chromatography-electrospray ionization-mass spectrometry (LC/ESI/MS) method was used to identify momordicosides K and L in methanolic extracts of fresh and processed samples. Only extracted ion chromatographs for blanched bitter melon and bitter melon with MY 68 agent showed the absence of momordicosides K and L.