Gas sensor module, refrigerator having the same and control method for the refrigerator

A control method comprising:

• using an aqueous solution, in which ion pairs of a substance having a substantially same dissociation constant as that of a target gas are dissolved, and a gas sensor module, which is configured to sense a pH change of the aqueous solution that occurs due to the target gas being dissolved in the aqueous solution and indicate the pH change by producing at least one of a signal generated based on the pH change and a color change in accordance with the pH change, to sense the pH change in response to the target gas being dissolved in the aqueous solution;
• determining the concentration of the target gas based on the at least one of the signal generated based on the pH change and the color change of the gas sensor module in accordance with the pH change;
• and
• determining a state of target food based on the determined concentration of the target gas.