Comparative effects of irradiation, fumigation, and storage on the free amino acids and sugar contents of green, black and oolong teas

Food irradiation or chemical fumigation can be used to ensure the hygienic quality of teas. The comparative effects of gamma irradiation (5 and 10 kGy) and fumigation (MeBr and PH3) were investigated on the amino acids and sugar contents of Camellia sinensis (green, black and oolong teas) during storage (15±12 °C). The major amino acids found in teas were theanine and glutamic acid. Irradiation increased amino acids such as, leucine, alanine, and glutamic acid, and decreased the histidine. PH3 fumigation resulted in a decrease of tyrosine content; however, the effect of MeBr fumigation was negligible. Storage showed no significant effect on the amino acid content of the irradiated and fumigated teas. Sucrose, glucose, and fructose contents significantly increased upon gamma irradiation (p≤0.05). However, fumigation and subsequent storage did not affect the sugar contents. Irradiation could be a preferred alternative choice to address food safety problems as fumigation is restricted in many countries.

► Teas were investigated for the changes during storage on irradiation & fumigation.
► The effect on amino acid contents was more prominent on irradiation than fumigation.
► The sucrose, glucose, and fructose contents increased on gamma irradiation.
► Fumigation and storage did not affect the sugar contents in the teas.
► Irradiation could be an effective alternative for fumigants.