IONIZING RADIATION INDUCES FORMATION OF MALONDIALDEHYDE, FORMALDEHYDE AND ACETALDEHYDE FROM CARBOHYDRATES AND ORGANIC ACID

Authors: Fan, Xuetong

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2003
Publication Date: 8/30/2003
Citation: FAN, X. IONIZING RADIATION INDUCES FORMATION OF MALONDIALDEHYDE, FORMALDEHYDE AND ACETALDEHYDE FROM CARBOHYDRATES AND ORGANIC ACID. JOURNAL OF AGRICULTURE AND FOOD CHEMISTRY. 2003. V. 51. P. 5946-5949.

Interpretive Summary: Malondialdehyde (MDA), formaldehyde (FA) and acetaldehyde (AA) are naturally occurring compounds commonly found in variety of foods. MDA and FA, at high concentrations, may be carcinogenic in animals. AA can have a negative impact on flavor. Our earlier study suggested that ionizing radiation increased formation of MDA, FA and AA in apple juice. Apple juice contains high amounts of carbohydrates and malic acid. However, it is unclear whether these aldehydes are generated from carbohydrates or malic acid. Accordingly, a study was conducted to investigate formation of these aldehydes from carbohydrate and malic acid in aqueous solutions, and to study effect of pH and substrate concentration on the formation of these compounds. MDA and FA were generated from the carbohydrate solutions upon irradiation while little was formed from malic acid solution. On the other hand, a much higher amount of AA was formed from malic acid than from the carbohydrate solutions. pH had a profound effect on the irradiation-induced formation of these compounds from carbohydrates, especially on MDA formation. The minimum amount of MDA from fructose and glucose solutions was observed at pH 5 while formation of MDA from sucrose solution decreased as pH decreased from 7 to 2. The results of this study can be used by food industry to optimize food formulation in order to minimize formation of these aldehydes due to irradiation.

Technical Abstract: A study was conducted to investigate factors affecting irradiation-induced formation of malondialdehyde (MDA), formaldehyde (FA) and acetaldehyde (AA) from fructose, sucrose, glucose and malic acid solutions. MDA and FA were generated from the carbohydrate solutions upon irradiation while little was formed from malic acid solution. On the other hand, a much higher amount of AA was formed from malic acid than from the carbohydrate solutions. The G-values (number of molecules formed per 100 ev radiation) for MDA were 0.042, 0.0066, and 0.0026 from 0.9 mg/ml fructose, sucrose, and glucose solutions at pH 3.5, respectively. The G-values for FA formation were 0.134, 0.233 and 0.0081 from the fructose, sucrose, and glucose solutions, respectively. As concentration of sugars in solutions increased from 0 to 90 mg/ml, the formation of these compounds increased rapidly. Further increase in sugar concentration from 90 mg/ml to 900 mg/ml resulted in a lower rate of increase in MDA and FA formation. pH had a profound effect on the irradiation-induced formation of these compounds from carbohydrates, especially on MDA formation. The minimum amount of MDA from fructose and glucose solutions was observed at pH 5 while formation of MDA from sucrose solution decreased as pH decreased from 7 to 2. The results can be used by food industry to optimize food formulation in order to minimize formation of these aldehydes.