The respiration rate (mL CO2 kg 1 h

The respiration rate (mL CO2 kg 1 h 1) of raw carrots was measured using a closed system at 0, 4, and 20 C (Kader, 1992). Fresh roots (about 300 g for each carrot type) were put into 6 L sealed plastic jars, where carbon dioxide was allowed to accumu- late until the value of a standard gas mixture containing carbon dioxide and nitrogen (0.1e99.9% Sapio, Milan, Italy) was reached.
Then, a 1 mL gas sample was taken from the head space through a rubber septum and injected into the gas chromatograph (Agilent p200 micro GC, Santa Clara, CA, USA) equipped with dual columns and a thermal conductivity detector. Carbon dioxide was analyzed with a retention time of 16 s and a total run time of 120 s on a 10 m PPU column at a constant temperature of 70 C.
Q10 values were also calculated for each carrot type using the formula reported by Labuza (1982). Firmness was measured on whole peeled raw roots with a machine texture analyzer (Zwick- Line Z0.5, Zwick/Roel, Ulm, Germany), using a puncture method and expressed in Newton (N).
Next, in order to measure dry weight, chopped carrots and jam were maintained in a forced-draft oven at 65 C until constant weight was reached.