Author
 |
Beaulieu, John |
|
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/9/2007 Publication Date: 5/28/2007 Citation: Beaulieu, J.C. 2007. Effect of UV irradiation on cut cantaloupe: terpenoids and volatiles. Journal of Food Science. 72:S272-S281. Interpretive Summary: Recent studies demonstrated that ultraviolet (UV) light enhanced the terpenoid compound levels, and simultaneously decreased ester compounds in thin-sliced cantaloupe. In preliminary studies, treating fresh juices with UV, terpenoid compounds that normally were not isolated, or found in minute quantities, were elevated and only low molecular weight alcohols, ketones, and aldehydes decreased. Concomitant decreases in the ester content of UV-treated samples also occurred. However, studies in our laboratory have seldom observed severe declines in volatile esters during storage as fresh-cut products. Subsequently, terpenoid induction/oxidation in UV-treated cut cantaloupe was re-investigated. UV exposure increased the concentrations of terpenoid compounds in cantaloupe tissue. However, UV exposure alone was not the sole factor responsible for enhanced terpenoids. UV-enhanced terpenoid production appears to be both cultivar- and maturity-dependent. We also established that almost identical ester losses occurred in thinly sliced tissue receiving 60 minute UV- or air-exposure in an identical (open) system. Tissue samples that were exposed to UV in a closed system (static air movement) often did not suffer correspondingly equal ester loss. Tissue warming also occurred during UV treatments in thin-sliced tissue. Ester loss from cantaloupe tissue was caused by the experimental procedure, but not by UV treatment, per se. Information gathered indicates that improper cutting, handling, sanitation treatment, and storage can radically alter the desirable volatile profile in cut cantaloupe, and potentially lead to decreased consumer acceptance. Manufactures of UV equipment for the fresh-cut food industry have a challenge to engineer equipment and technology required to simultaneously protect operators, while effectively treating cut fruit tissue to insure significant and consistent microbial load reduction. Technical Abstract: Recent studies demonstrated that ultraviolet (UV) radiation enhanced terpenoids, and decreased esters in thin-sliced cantaloupe. In preliminary studies, treating fresh juices with UV, terpenoid compounds that normally were not isolated, or found in minute quantities, were elevated and only low molecular weight alcohols, ketones, and aldehydes decreased. Subsequently, terpenoid induction/oxidation in UV-treated cut cantaloupe was re-investigated. UV exposure increased the concentrations of terpenoids in cantaloupe tissue. However, UV exposure alone was not the sole factor responsible for enhanced terpenoids. UV-enhanced terpenoid production appears to be both cultivar- and maturity-dependent. Concomitant decreases in the ester content of UV-treated samples occurred using a previously published system. We established that almost identical ester losses occurred in thinly sliced laminar tissue receiving 60 minute UV- or air-exposure in an open system. Tissue samples that were exposed to UV in a closed system often did not suffer correspondingly equal ester loss. Marked tissue warming (4.3 ' 0.5°C in 60 minutes) occurred during UV treatments in thin-sliced tissue. Ester loss from cantaloupe tissue was caused by the experimental procedure, but not by UV treatment per se. These findings are supported by the fact that UV is not responsible for chemical transformations to ester bonds, esterase, and lipase decrease in stored cut cantaloupe; and no lipid oxidation volatiles were observed in thin-sliced control tissue, while oxidized terpenoids were recovered. Information gathered indicates that improper cutting, handling, sanitation treatment, and storage can radically alter the desirable volatile profile in cut cantaloupe, and potentially lead to decreased consumer acceptance. |
