Effects of Composite Modified Atmosphere Packaging on Anaerobic Respiration Metabolism of Garlic Bulbs

Anaerobic respiration metabolism plays an essential role in the controlled atmosphere storage process of fruits and vegetables. In this study, the effects different volume fractions of CO₂（5%, 8%, 11%, and 14%） treatments on the indicators’ changes including pyruvate, pyruvate decarboxylase（PDC）, alcohol dehydrogenase（ADH）contents, respiration rates, ethylene release rates of garlic under 4 ℃ storage were investigated with the fixed O₂ volume fraction of 3.5%, in order to study the effects of composite modified atmosphere packaging on anaerobic respiratory metabolic pathways and related physiology of garlic. Results indicated that during storage, the pyruvate contents of garlic decreased continuously, while the PDC and ADH activities showed an increasing trend, and the CO₂ volume fractions presented significant effects on enzymes activities, especially when CO₂ volume fraction exceeded 8%. The trend of ethylene release rates was similar to that of respiration rates. The peaks appeared first at low volume fractions CO₂ storage, and the ethylene release and respiration intensity were continuously increased at high CO₂ volume fractions. The comprehensive analysis showed that when garlic bulbs were stored at low temperature（4 ℃） and 3.5% O₂, the ideal ratio was that the volume fraction of CO₂ was not higher than 8%. Under these conditions, the pyruvate metabolism related enzymes activities were effectively inhibited, and the accumulation of harmful substances was reduced, meanwhile the ethylene release rate and respiratory intensity were also inhibited.