Measurement of Broccoli Respiration Rate in Film-wrapped Packages

Broccoli ( Brassica oleracea L., Italica Group) was held at 5°C in a stream of humidified air (control) or of humidified 14% O 2 /10% CO 2 (CA), or it was wrapped with a nonperforated flexible polyvinylchloride (PVC) film and held in a humidified (90% to 95% RH) or nonhumidified (40% to 45% RH) stream of air for 3 weeks. Water loss was reduced 17% by the CA treatment and 50% by wrapping the broccoli. Broccoli stored in CA or wrapped in film retained quality significantly better than the controls. Atmosphere composition within packages reached equilibrium within the first 24 hr and did not change significantly over the 3 weeks. Self-generated atmosphere modification was greater within packages held in humidified air than within those held in nonhumidified air (7.8% vs. 13.2% O 2 ; 9.0% vs. 6.7% CO 2 , respectively). The steady state of atmospheres within packages allowed the calculation of respiration rates of wrapped broccoli by monitoring changes in the air surrounding the package. Oxygen consumption and CO 2 production by samples held in CA or in films were reduced 30% to 40% relative to the controls. The respiratory quotient for the CA and humidified wrapped samples was about 1.30, but 1.15 in the control and nonhumidified wrapped samples.