Eco-friendly food preservation: Studies on the synergistic preservative effect of Chitosan and soap nut solution

Abstract

Chitosan (CS), the antimicrobial, biopolymer with film forming nature, has been used as a topical preservative for food items like vegetables, fruits, and even for sea food.1In order to have different choices for preservation; we need to search for more materials with such properties. Soap nut (SN), whose botanical name is Sapindus mukorossi, seems to have similar properties. It is saponin, the major component present in soap nut, which is responsible for its antimicrobial and film forming property. There are many reports to support that up to a certain limit saponin can be used for edible purpose.2In this study the synergistic preservative effect of chitosan and soap nut aqueous solutions on fruits and vegetables was evaluated. At first, the antimicrobial effect of CS, SN and [CS+SN] in the film form was studied against Staphylococcus aureus and Escherichia Coli. As expected the film CS+SN exhibited more antimicrobial activity with 25 mm and 23mm zone of inhibition against Staphylococcus aureus and Escherichia Coli respectively. The potential of CS+SN as a preservative was evaluated by spraying a known concentration on different regional fruits like lemon, banana, tomato and orange. Different concentrations of [CS+SN] - 250ppm and 125ppm, along with CS-500ppm, SN-500ppm and water, were compared, where water served as the control. Fruits sprayed with [CS+SN]-250ppm solution, showed significant delay in the change of weight loss, decay percentage, pH, as compared to control fruits. It also maintained better visual quality than CS and SN coated as well as control samples. These findings suggest that [CS+SN], with its synergistic preservative potential will maintain the fruit quality and lead to better acceptance by consumers. Thus Chitosan along with soap nut solution will be a cost effective, eco-friendly and easy to utilize preservative system.