Degree Type


Date of Award


Degree Name

Master of Science


Agricultural and Biosystems Engineering

First Advisor

Jacek A. Koziel

Second Advisor

Johannes Van Leeuwen


The commercial production of fruit leathers results in some material that is not to specification. Although this product remains edible and contains valuable ingredients such as fruit pulp, sugars and acidulates, it is not salable and its disposal is costly. Because these products are typically highly colored, recovery of fruit leather for recycling into the product requires colorant removal to avoid an unappetizing brownish color from the mixture of colorants. This research introduces a novel approach utilizing ozonation for color removal. The treatment was first applied to pure solutions of the commonly used food colorants 2-naphthalenesulfonic acid (Red 40), tartrazine (Yellow 5), and erioglaucine (Blue 1). Color removal was measured by UV/Vis spectrometer, and a Hunter colorimeter. Byproducts from ozone-based colorant decomposition were identified and quantified with SPME-GC-MS. Removal of Yellow 5, Red 40 and Blue 1 was about 65%, 80% and 90% complete, respectively, with 70 g ozone applied to 1 kg aqueous fruit leather suspension solution. Given the known structures of these dyes, a concern with this approach is the potential formation of toxic ozonolysis byproducts. In initial work, carbonyl compounds were identified as major byproducts. Among these, benzaldehyde, 2-furfural, ethanal and hexanal were identified as byproducts of known toxicity at levels sufficient for concern. A head-space solid-phase microextraction (HS-SPME) method with on-fiber derivatization using o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was optimized for detection and quantification of carbonyl compounds in ozonated fruit leather suspensions. Ethanal, hexanal, furfural and benzaldehyde were quantified with the newly developed method, and detection limits were in the range of 0.016 - 0.030 yg/L. For furfural, the ozonolysis byproduct noted in the literature as having the highest median lethal dose value, the maximum amount generated was determined to be under the detection limit, 0.016 yg/L of 100% fruit leather solution/suspension, while hexanal was the most abundantly generated, at 80.0 y 22.0 mg/L. A conservative risk assessment based on published toxicity information for the main ozonolysis products generated in this study suggests the acceptability of ozone-based decolorization in fruit leather recycling. A preliminary cost estimate suggests a potential $0.25 million annual profit on recycling a 1,000 tons of waste fruit leathers per year.

Copyright Owner

Wenda Zhu



Date Available


File Format


File Size

58 pages