Masters Theses

Date of Award

12-2005

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science and Technology

Major Professor

John Mount

Committee Members

Svetlana Zivanovic, Carl Sams

Abstract

Edible coating has been applied on the surface of fresh produce to extend shelf-life by suppressing respiration, transpiration, and microbial growth. The coatings, thus, can help decrease moisture and weight loss, and may offer a protective barrier against bacterial contamination and spoilage. Recent studies have indicated chitosan as an effective coating that extends shelf-life and improves a storability of fruits. The objective of this study was to demonstrate the effectiveness of natural biodegradable chitosan coatings in extending shelf-life and quality of fresh small fruits, such as blueberries and grapes. Fruits were dipped for 30 seconds in 1% chitosan in 1% aqueous acetic acid, 1% water-soluble chitosan in water, 1% acetic acid solution or tap water. Non-treated fruits served as a control treatment. Samples were stored at 4±1°C and 85±5% RH up to 24 days. Quality analysis was performed every 3 days. The analysis included measurements of texture, color, weight loss, and ethylene and CO2 production. Statistical analysis was conducted for all dip treatments and control fruit. For blueberries, ethylene production (0.038ppm/hr to 0.194ppm/hr; p0.05). - iv - Grapes dipped in chitosan solutions had a slight but significant difference in ethylene production (0.01ppm/hr to 0.05ppm/hr; p0.50). There was no significant changes in firmness among chitosan, soluble chitosan, and control grapes, but there were differences between grapes dipped in chitosan and water treatments and between chitosan and acetic acid treated grapes (p0.10) among treatments. For blueberry samples, non-coated (control) had slightly bluer than chitosan treated fruits but chitosan treated grape samples were slightly more yellow color than control. There was no significant change in moisture loss from the fruit (p>0.10) among the treatments. The visual appearance of fruit samples did not significantly differ between water soluble chitosan treated and control but there was difference between chitosan in acetic acid treated samples and control. Chitosan in acetic acid treated samples left a thin layer film on the fruit skin that can be easily removed when washed with water. The results suggest that chitosan coatings may be used on small fruits to maintain quality and extend shelf-life.

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