Preparation and characterization of Chitosan-Poly (methacrylic acid) nanoparticles and its incorporation in mango peel pectin-based nanocomposite coatings for the shelf-life extension of mango (Mangifera indica L. cv carabao) fruits

Date

4-2012

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Veronica C. Sabularse

Restrictions

Restricted: Not available to the general public and to those bound by the confidentiality agreement. Access is available only after consultation with author/thesis adviser.

Abstract

Chitosan with a molecular weight of 223 kDa was hydrolyzed using acidic hydrogen peroxide to obtain low molecular weight chitosan. Chitosan-poly(methacrylic acid) nanoparticles were prepared by polymerization of methacrylic acid in a solution of low molecular weight chitosan of 0.50% and 0.80% w/v concentration. The mean sizes of nanoparticles were 198±41 nm for 0.50% chitosan and 119±34 nm for 0.80% chitosan. The nanoparticles were used in pectin-based coating formulations. Pectin was extracted from mango fruit peels which were obtained from ripe Carabao mango fruits. Pectin characterization was conducted by determining its viscosity, molecular weight, degree of polymerization, total sugars content and uronic acid content. Its viscosity, molecular weight and degree of polymerization were 0.480 dL/g, 37,130 Da and 191, respectively. Its total sugars content and uronic acid content were 32.78±0.97% and 38.04±1.16%, respectively. Coating formulations using pectin as base into which chitosan-poly(methacrylic acid) nanoparticles were incorporated were prepared. The effect of size and concentration of nanoparticles were evaluated in preliminary coating test. Carabao mango fruits were coated with coating formulations and were stored at ambient temperature. The coating formulation containing 2% pectin + 20.7% (v/v) 119 nm chitosan poly(methacrylic acid) nanoparticles + additives was the most effective formulation. In the final coating test, coating formulations based from the preliminary test were prepared. Carabao mango fruits were coated with these formulations and stored at 10 °C and 90 to 95% relative humidity (RH). On the last day of storage sampling, which was day 25, the coating formulation containing 2% pectin and chitosan-poly(methacrylic acid) nanoparticles without additives proved to be most effective. It was effective in retarding peel color change and in minimizing disease incidence, weight loss and shriveling. No significant difference on the effect of coatings on pH, percent titratable acidity, total soluble solids, reducing sugar content and total sugars content of mango fruits were observed. A remaining set of mango fruits for each treatment designated for non-destructive physical analyses was continued to be stored under the same conditions beyond 25 days. On the 30th day of storage, mango fruits coated with the nanocomposite coating without additives were still fairly marketable based on their physical qualities.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2012 C42 /S67

Document Type

Thesis

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