91E-16 |
Accumulation of malonaldehyde, formaldehyde and acetaldehyde in irradiated apple juice |
X. FAN, USDA-ARS-Eastern Regional Research Center, 600 E. Mermaid Ln., Wyndmoor, PA 19038-8598 and D. W. Thayer. Ionizing radiation effectively inactivates foodborne pathogens in various foods. Irradiation may, however, promote synthesis of carbohydrate-derived aldehydes that may be carcinogenic and impact flavor. Therefor the accumulation of these aldehydes in carbohydrate-rich foods is a concern. The objectives of this study were to determine the amount of malonaldehyde (MA), formaldehyde (FA) and acetaldehyde (ACT) in apple juice as affected by radiation dose and subsequent storage 5oC, and to explore means of reducing the accumulation of these compounds. MA in gamma-irradiated apple juice was measured using a newly developed gas chromatograph-mass spectrometer (GC-MS) method in comparison to the thiobarbituric acid (TBA) assay. The MA-radiation dose relationship was similar when MA was determined using both methods, however, MA content was seriously overestimated when measured with the TBA assay compared to the GC-MS method. The overestimation of MA using the TBA assay increased as the amount of MA decreased. The GC-MS method also allowed measurement of FA and ACT in addition to MA. The formation of MA, FA, and ACT increased as dose increased. MA content decreased rapidly during storage at 5oC while ACT and FA did not. Irradiation-induced formation of MA, FA and ACT decreased with decreasing irradiation temperature. Exclusion of oxygen during irradiation reduced formation of ACT and FA, not MA. Addition of 1000 ppm ascorbic acid, sorbate or sulfite to juice prior to irradiation also decreased formation of MA. Our results indicate that formation of these compounds was promoted by irradiation. The accumulated MA decreased rapidly during storage. The irradiation-induced formation of these compounds can largely be reduced by irradiation at low temperature, by the addition of antioxidants, and by exclusion of oxygen during irradiation.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
|