Effect of Different Dosage Rates on Radical Content and Volatile Compounds of Irradiated Yeast Extract
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Abstract:
Yeast extract (YE) was irradiated respectively by γ-rays with dosage rate of 60 and 480 Gy/min and electron beams of 12000 Gy/min. The volatile compounds from irradiated YE and five kinds of target amino acid-water solutions were detected by gas chromatograph- mass spectrometer-computer (GC-MS), the composition of YE volatile compounds and their amino acid source were investigated. The radical characteristics of irradiation YE were researched by electron sin resonance (ESR) and the mechanism of dosage rate on reducing irradiation damage was studied. Results showed that the six same volatile compounds from three irradiation treatments were acetone, acetic acid, methyl disulfide, toluene, 2,6-dimethyl-pyrazine and benzaldehyde. The number of volatile compounds and YE content increased during the first 14 days and then decreased during 14~35days after irradiation. The essential constitutes of amino acids were Met, Ala and Phe from YE degradation. The order of volatile content of YE with same absorbed dosage was: 60 Gy/min γ-rays＞480 Gy/min γ-rays＞electron beams. The ESR spectrum of YE was a double peak and the peak changed with dosage and dosage rate. YE irradiated by 60 Gy/min γ-rays was detected by ESR and showed that the ESR signal intensity was positively correlated with absorbed dosage and the linear fitting equation was: A=4363.5D+4873.9, R2=0.9826. The sequence of ESR signal intensity of YE with same absorbed dosage was: 480 Gy/min γ-rays < electron beams <60 Gy/min γ-rays. Therefore, high dosage rate irradiation can produce low radical intensity and reduce the volatile content production.
