The Comparison and Analysis of Two Extraction Methods for Polysaccharides in Psidium guajava L. Fruits

Introduction: Fruit polysaccharides, essential health factors in foods, are widely present in edible fruits. Several methods for isolation of polysaccharide are available. Microwave Assisted Extraction (MAE) method is extensively used for separation of polysaccharides. Only little information is available about Psidium guajava L. Fruit Polysaccharide (PFP) and its extraction methods. Objective: In this study, two extraction methods of polysaccharides in Psidium guajava L. fruit were compared and the best method was ascertained. Methods: Psidium guajava L. polysaccharides were extracted using water extraction with conventional heating and microwave assisted extraction method. The factors that influenced water extraction with conventional heating included temperature, water to plant material ratio, extraction time and solvent to liquid ratio. The factors that influenced MAE of polysaccharides extraction included microwave power, irradiation time and solvent to liquid ratio. Yield is considered as the independent variable in both the methods. Results: By the result of the single factorial method and orthogonal experiments, the optimal extracting conditions were selected and then the best extraction method was ascertained. The optimum extraction conditions of water extraction with conventional heating include, temperature 90oC, water to plant material ratio 1:1, extraction time 1 hour 30 min and solvent to liquid ratio 2:1. The results showed that the extraction yield of microwave method was higher under the optimal conditions of irradiation time 20 min, microwave power 200 W and 3:1 solvent to liquid ratio than the water extraction with conventional heating.