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Effect of chitosan and water soluble chitosan coatings on quality of small fruits

by Noh, Jason Ki-Myung.

Abstract (Summary)
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; p < 0.01) and carbon dioxide production (2.6% to 6.5%; p < 0.05) decreased significantly for both chitosan treatments compared to control fruit. However, there was no significantly difference of fruit skin firmness among the chitosan treated samples and control treatments (p > 0.05). - iv - Grapes dipped in chitosan solutions had a slight but significant difference in ethylene production (0.01ppm/hr to 0.05ppm/hr; p < 0.05) but no significant difference in CO2 production (p>0.50). 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 (p < 0.01). For all samples, Hunter b-values (p < 0.01) were significantly different among the grapes and blueberries but no significant changes in L or a-values (p > 0.10) 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. - v -
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School:The University of Tennessee at Chattanooga

School Location:USA - Tennessee

Source Type:Master's Thesis

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