Effect of minimal processing conditions on respiration rate of carrots.

ABSTRACT

Measurement, analysis, and modeling of respiration rate (RR) of fresh produce are fundamental for the engineering design of MAP. This study investigates the effect of type of cutting (sliced in circular shape, batons in rectangular shape, and shredded into thin strips) on the respiration rate of carrots at different temperatures (4, 8, 12, 16, and 20 degrees C) with ambient atmosphere. The higher respiration rates were found for shredded carrots and the lowest for whole carrots at all the temperatures tested. The RR increased from 9 +/- 1 to 26 +/- 3, 10 +/- 1 to 53 +/- 2, 11 +/- 1 to 55 +/- 2, and 18 +/- 1 to 75 +/- 3 mL of O(2) per kilogram hour for whole, sliced, baton, and shredded carrots, respectively, as the temperature increased from 4 to 20 degrees C. On an average, RO2 and RCO2 were increased by 85% and 64%, 100% and 72%, and 151% and 124% for sliced, baton, and shredded carrots, respectively, compared to the RR values of whole carrots. The temperature dependence of RR followed an Arrhenius-type relationship for all types of carrots, with activation energies in the range of 35 +/- 3 to 62 +/- 2 kJ/mol. Type of cut was the major factor for both RO2 and RCO2, with shredded carrots having the highest rates and whole carrots the lowest. RR of whole carrots did not vary during storage, whereas it increased for cut carrots and especially for shredded carrots. The respiratory quotient (RQ) increased with temperature and did not vary during storage in all types of carrots, except the RQ of whole carrots decreased significantly over time.