青花菜的呼吸强度较高，采后生理代谢活动非常旺盛，短时间内就会失去水份变黄，影响蔬菜本身的商品价值。所以蔬菜采后必须及时进行预冷，迅速除去田间热，降低青花菜中心温度和呼吸强度，从而达到减缓蔬菜的新陈代谢活动和延长保鲜期的目的。目前国内蔬菜产地预冷环节薄弱，缺乏专业性预冷设施;运输过程中很少采用冷藏运输，农贸市场、超市等零售环节大多采用常温无包装销售，销售果蔬的设施基本为普通货架、普通货架加喷湿装置(RH:80%～90%)和冷藏陈列柜(2～10℃)。中国蔬菜流通腐损率为25%～30%，这就是中国目前蔬菜的流通现状。
Broccoli has a high respiratory intensity, and its postharvest physiological and metabolic activities are very vigorous. In a short period of time, it will lose water and turn yellow, affecting the commercial value of vegetables themselves. Therefore, vegetables must be pre-cooled in time after harvest, quickly remove heat from the field, reduce the central temperature and respiratory intensity of broccoli, so as to slow down the metabolism of vegetables and prolong the preservation period. At present, the precooling links of domestic vegetable producing areas are weak and lack of professional precooling facilities; refrigerated transportation is seldom used in the transportation process; most of the retail links such as farmers'markets and supermarkets sell fruits and vegetables at normal temperatures without packaging; the basic facilities for selling fruits and vegetables are ordinary shelves, ordinary shelf humidifying devices (RH: 80%-90%) and refrigerated display cabinets (2-10%). C). China's vegetable circulation loss rate is 25% to 30%, which is the current situation of vegetable circulation in China.
做个简单在试验：选择新鲜、清洁、大小均匀、无机械伤和病虫害，直径为15～20cm，长为15cm左右的青花菜(单个重约为200研究压差预冷和冷库预冷，聚苯乙烯泡沫箱加冰0℃冷藏运输1天，4℃和20℃加收缩膜和不加收缩膜包装及20℃加湿销售2天青花菜品质的变化。结果表明:压差预冷青花菜的预冷速度快于冷库预冷;聚苯乙烯泡沫箱加冰冷藏运输1天后，4℃销售的青花菜品质好于在20℃下销售青花菜的品质。
A simple experiment: choose fresh, clean, uniform size, no mechanical injury and pests. The diameter of the broccoli with a diameter of 15 to 20cm is about 15cm. (a single weight is about 200, the pressure difference is pre cooled and the cold store is pre cooled, the polystyrene foam box is iced at 0 degrees, the refrigerated transportation is 1 days, the 4 and 20 degrees are added shrink film and no shrink film packaging and 20 days. The quality of broccoli was changed 2 days at the temperature. The results showed that the pre cooling rate of broccoli with pressure difference pre cooling was faster than that of cold storage. When the polystyrene foam box was refrigerated for 1 days, the quality of broccoli sold at 4 degrees Celsius was better than that of broccoli at 20 degrees Celsius.