Isolation of Low Molecular Weight Carbohydrates from Seeds of SyzygiumCuminiandan Investigation into their Prebiotic Properties

Abstract

Syzygium cumini(L.) Skeels (jamun) is a medically important fruit with numerous health protective effects. Seeds of this fruit contain 74.5 % NFE (nitrogen free extracts) and therefore possess a good source of carbohydrates. This fraction consists of high molecular weight carbohydrates (HMWC) like inulin (41.1 %) and resistant starch (3.9 mg/L); and hitherto unquantified low molecular weight carbohydrates (LMWC). This study was performed to extract and quantify LMWC from jamun seeds. To extract LMWC, ethanol concentration, extraction time and solute particle size were evaluated in 21 experimental designs using Response Surface Methodology (RSM) based on the central composite rotatable design (CCRD). A quadratic polynomial equation was obtained by multiple regression analysis. Analysis of variance (ANOVA) tested significance of the factors and their interactions at 95 % confidence interval. High Performance Anion Exchange Chromatography – Pulsed Amperometric Detection (HPAEC-PAD) was used to characterize the prebiotic fraction into individual sugars. Prebiotic potential of LMWC was established by calculating the Prebiotic Activity Score (PAS). A maximum LMWC yield (21 g / 100 g) was obtained when extraction was performed with 50 % ethanol as solvent for 80 to 85 h using the seed powder with 0.6 mm particle size. The predicted yield was in agreement with the experimental value and therefore proved the suitability of the RSM model. This model could be used as a standard for scaling up LMWC extraction from jamun seeds. A positive PAS of 1.532 ± 0.008 ascertained the prebiotic efficacy of the LMWC extracts. This score reflected the ability of probiotics like Lactobacillus acidophilus to gainfully utilize the LMWC in the growth medium in comparison to pathogenic strains like Escherichia coli.