Head diameter and compactness; all florets (beads) should be closed
Good quality broccoli should have dark or bright green closed florets, and the head should be compact (firm to hand pressure), with a cleanly cut stalk of the required length.
Optimum Temperature and Relative Humidity
Low temperature is extremely important to achieve adequate shelf-life in broccoli. A temperature of 0°C (32°F) with >95% RH is required to optimize broccoli storage life (21-28 days). Heads stored at 5°C (41°F) can have a storage life of 14 days; storage life at 10°C (50°F) is about 5 days. Broccoli is usually rapidly cooled by liquid-icing the field-packed waxed cartons. Hydrocooling and forced-air cooling also can be used, but temperature management during distribution is more critical than with iced broccoli.
Freezing Injury Broccoli
This may occur if salt is used in the liquid-ice cooling slurry or if noniced broccoli is stored below -1°C (30°F). Frozen and thawed areas on the florets appear very dark and translucent, may turn brown after thawing and are very susceptible to bacterial decay.
Rates of Respiration
سر بروکلی ها نرخ تنفس نسبتا بالایی دارد.
Broccoli heads have relatively high respiration rates:
The respiration rates of florets are slightly more than twice the rates of the intact heads.
To calculate heat of production multiply ml CO2/kg·hr by 440 to get Btu/ton-day or by 122 to get kcal/metric ton-day.
Rates of Ethylene Production
Very low, <0.1 µL/kg·h at 20°C (68°F)
Responses to Ethylene
Broccoli is extremely sensitive to exposure to ethylene. Floret yellowing is the most common symptom. Exposure to 2 ppm ethylene at 10°C (50°F) reduces shelf-life by 50%.
Responses to Controlled Atmospheres (CA)
Broccoli can be benefitted by 1-2% O2 with 5-10% CO2 atmospheres at a temperature range of 0-5°C (32-41°F). Although under controlled conditions such low O2 levels extend shelf-life, temperature fluctuations during commercial handling make this risky as broccoli can easily produce offensive sulfur-containing volatiles. As a result, a high rate of air exchange is recommended in standard marine container shipments of broccoli. Most modified atmosphere packaging for broccoli is designed to maintain both O2 and CO2 at about 10% to avoid the development of these undesirable off-odor volatiles.