Development and quality evaluation of bitter gourd (Momordica charantia L.) based low calorie dietetic beverages

Abstract

Bitter gourd occupies a prominent position among the vegetables grown in India. The importance of bitter gourd has long been recognized due to its nutritive value and medicinal properties. It contains a unique phytoconstituent namely charantin that has been confirmed to have hypoglycemic effect. There is also an insulin like compound known as polypeptide P which has been recommended as an insulin replacer in diabetic patients. The present study entitled “Development and quality evaluation of bitter gourd (Momordica charantia L.) based low calorie dietetic beverages” was aimed to standardise low calorie bitter gourd based dietetic beverages and to evaluate the chemical, nutritional, organoleptic and shelf life qualities of the products. Standardisation of RTS beverages from bitter gourd and its blend with ash gourd was carried out in 18 treatments. Sugar, low calorie sweetener and salt based beverages were tried. For flavouring, cardamom and ginger drops were used. Based on organoleptic evaluation, the most acceptable beverages ie., two each from sugar based, low calorie sweetener based and salt based were selected for storage study. Thus, twelve beverages were selected. The selected beverages were prepared and stored for three months at ambient and refrigerated conditions. Organoleptic qualities, chemical constituents and shelf life qualities were evaluated initially and monthly intervals for a period of three months. The β carotene and total phenol content in RTS beverages showed a significant difference during ambient and refrigerated storage whereas the variation observed in total soluble solids (TSS), total sugar, reducing sugar and vitamin C content was statistically insignificant. The acidity of RTS beverages increased during storage at ambient condition, but a decreasing trend was noticed under refrigerated condition. The loss of ascorbic acid was more in beverages stored under ambient condition, compared to RTS beverages stored in refrigerated condition. The phenol content was found to be low in RTS beverages prepared by blending bitter gourd and ash gourd juice. The duration and conditions of storage had no influence on the mineral constituents of the beverages. The beverage prepared with equal quantity of bitter gourd and ash gourd juice with salt and one drop of cardamom was found to be nutritionally superior when stored under refrigerated condition. A gradual decrease in organoleptic qualities of the beverages like appearance, colour, flavour, taste and overall acceptability was noticed during storage. The RTS beverage prepared using bitter gourd and sugar attained maximum mean scores followed by beverages prepared with bitter gourd juice + low calorie sweetener and bitter gourd juice + sugar and flavoured with cardamom drops. The same trend was observed under both storage conditions. The bitter gourd based dietetic RTS beverages were evaluated initially and at monthly intervals for bacteria, yeast and fungi for a period of three months. Yeast and fungi were not detected in any of the beverages throughout the storage period. At the end of third month of storage the presence of bacteria was observed in all the treatments stored under ambient and refrigerated conditions, but they have not exceeded the permissible threshold levels of microbial population. The RTS prepared with bitter gourd and sugar was found to be the best in organoleptic evaluation and consumer acceptance studies. Blending of bitter gourd juice with ash gourd juice and flavouring with spice drops improved the nutritional as well as organoleptic qualities of RTS beverages. To increase the consumption of bitter gourd as an anti diabetic vegetable, production of RTS beverage is a viable technology and it has ample scope for commercial exploitation.