A cost-effective extraction method for improved physicochemical, rheological and microbiological properties of grewia mollis gum

Abstract

Grewia gum is a versatile natural polymeric excipient and its preparation from Grewia mollis stem barks using chemicals and heat treatment may destroy useful phytochemical components and influence the physicochemical properties of the resultant product. There is a need to establish favourable processing and handling conditions to maintain the viscosity of Grewia mucilage throughout its shelf life. The study aimed to develop a simple and efficient technique to isolate Grewia gum from Grewia mollis stem barks and evaluate its organoleptic, physicochemical, microbial count and rheological profile. Grewia gum was prepared by aqueous maceration of stem barks of Grewia mollis. The successful isolation of reddish-brown Grewia gum was confirmed using FT-IR. The product yield was 67.7±1.9% w/w. The irregular shaped and rough-textured particles did not compromise its flowability (CI 15.3 ± 1.7%, HR 1.18±0.02, and AOR 17.6 ± 0.7o). Grewia gum displayed swelling index: 8.3 ± 2.1%; moisture content: 8.8 ± 0.8%; total microbial count 65 ± 1 CFU/g and pathogenic organisms were absent. Phytochemical constituents include Saponins, flavonoids, proteins, amino acids, triterpenoids, phenols, and carbohydrates. The highest mucilage viscosity of 4458 ± 33 mPas was obtained at 25oC, 10 rpm while 1431 ± 20 mPas was the lowest viscosity recorded at 45oC, 60 rpm under acidic conditions. Its satisfactory swelling index suggested its usefulness to formulate controlled release dosage forms. A new and cost-effective technique has been identified to extract Grewia gum. Grewia gum is a valuable substitute to synthetic and semi-synthetic polymeric excipients for pharmaceutical applications.