The straw includes a tube (11) extending between a first end (16) and a second end (17) and includes a gas-permeable but liquid-impermeable plug (12). The tube (11) is made of a thermochromic material that reversibly changes colour at a preset temperature threshold, by virtue of which colour change the tube (11) has a first visual appearance if the temperature thereof is below said preset threshold and a second visual appearance that is different from the first visual appearance if the temperature thereof is above said preset threshold.
