Abstract
Bitter gourd (Momordica charantia) known as, balsam pear or karela, is a member of the
Cucurbitaceae family. This plant is widely cultivated mainly for its fruits throughout the tropical
areas such as the Amazon, Africa, Asia and India. Among the gourds, the fruit of M. charantia
has found long history of use in culinary due to its high nutritional values, and in folk medicine
due to the abundant bioactive compounds. Recently, several studies have been conducted to
proof the anti-diabetic, anticancer, antidementia, hypolipidemic and hypotensive properties of
bitter gourds. While different processing and preservation techniques have been used on bitter
gourds, including thermal processing, steeping, sun-drying, and dehydration, only
considerable amount of research has been undertaken to process the bitter gourd into
beverages. This notable medicinal plant can be processed into different therapeutic and
functional products including alcoholic beverages. A standardization process was conducted
for extracting bitter gourd juice by sorting and washing the bitter gourd thoroughly in running
water to remove adhering foreign materials, cut on both ends and thereafter blended.
Standardization of temperature, time and starter culture concentration was done by applying
central composite design (CCD) of response surface methodology (RSM) for preparation of
the Fermented Bitter Gourd Grape Beverage (FBGGB). Optimized conditions to prepare
FBGGB resulted from 20 experimental runs generated by Design-Expert software version
11.0.0. The RSM models showed high accuracy in predicting optimum conditions for the
selected parameters. The R2 values for alcohol, pH and TSS models were 0.79, 0.89 and 0.89,
respectively, showing respective model accuracies of 79%, 89%, and 89%. RSM models were
successfully validated by the constructed Artificial Neural Network (ANN) with relatively high
accuracy. The TSS, alcohol and pH overall R2 values were 0.82, 0.98 and 0.88, respectively,
signifying high validation accuracy and reliability in prediction. The optimized conditions were
fermentation time (52.602 hours), fermentation temperature (28.594 °C), and starter culture
concentration (4.070 v/v). Fermented Bitter Gourd Grape Beverage (FBGGB) with and without
0.2% pectin esterase enzyme were found to have better physiochemical content when
compared to grape juice and bitter gourd juice, based on the physico-chemical and microbial
characteristics of FBGGB with the enzyme rated as the best as compared to FBGGB without
the enzyme. Fermented Bitter Gourd Grape Beverage (FBGGB) is a promising palatable
beverage which retains the vegetables medicinal properties.
Keywords: Momordica charantia, Fermented Bitter Gourd Grape Beverage, Response
Surface Methodology, optimum conditions.