Study on Extraction of Pectin from Coffea arabica Pericarp and Antibacterial Activity of Its Hydrolysate

Using pericarp of Coffea arabica as raw material,the extraction process of pectin was optimized by orthogonal experiment on the basis of single factor experiment,and the physicochemical properties and antibacterial activity of pectin were preliminarily determined. Results showed that,the optimum extraction conditions of pectin from Coffea arabica pericarp were as follows:The ratio of material to liquid was 1:30 g/mL,pH was 1.5,extraction temperature was 60 ℃,extraction time was 100 min,and the yield rate of pectin from coffee pericarp was 15.13% under these conditions. The galacturonic acid content of pectin was 67.71%,esterification degree was 70.07%,dry weightlessness was 10.17%,the total ash was 22.75%,pH was 2.61,acid insoluble ash was 1.57%,the physical and chemical indexes of pectin extracted from Arabica coffee pericarp met the requirements of national standard. The pectin hydrolysate from the pericarp of Arabica coffee had bacteriostatic activity against Escherichia coli,Bacillus subtilis and Staphylococcus aureus. The minimum inhibitory concentration(MIC)against Escherichia coli and Staphylococcus aureus was 8 g/L,the minimum bactericidal concentration(MBC)was 16 g/L,and the antibacterial activity was weaker than that of potassium sorbate. The MIC and MBC of pectin hydrolysate to Bacillus subtilis were 4 and 8 g/L respectively,and the bacteriostatic activity was similar to that of potassium sorbate. This study provided a theoretical basis for the comprehensive utilization of coffee pericarp waste.