Research On Cold Chain Logistics Technology And Its Key Craft Of Brassica Oleracea

Broccoli(Brassica oleracea)is a crisp,delicious,nutritious vegetable.In recent years,the planting area,production and consumption of broccoli have been increasing in China.But the planting area of broccoli is relatively concentrated in our country,and the planting area has obvious seasonality character.So the supply and demand contradiction is present between the regional,seasonal characteristics and all year round consumption demand.This contradiction,which require us to develop the technology of complete cold chain of broccoli as soon as possible,is particularly important for the development and application of freshness preservation technology of broccoli.The edible part of broccoli is the buds which is fresh and tender green,but after harvest,all kinds of metabolism is still very active.The broccoli stored at room temperature for 2d?3d would become yellow,dehydrated and wilted,and the nutrients rapidly be degraded resulting in the loss of its commercial value.The complete cold chain means that the broccoli is set at a suitable temperature from the field to the table,thereby reducing the temperature of the bulb,delaying the aging process of the bulb,maintaining the sensory quality and the nutritional value of the bulb,extending the shelf life and improving the commercial value.Therefore,the research on the technology and process of the complete cold chain of broccoli would be the key to solve the supply and demand contradiction of broccoli,and the application of freshness preservation technology broccoli.Focusing at three aspects including whether the cold chain be complete,packaging methods during sales,and improving of technological processes,this study was to explore the optimum technology and process of the complete cold chain of broccoli,to provide a theoretical basis and technical support for prolonging the shelf-life of and increasing the economic benefits of broccoli.The main contents and results of the study are as follows:1.The effect of refrigerated transport way on product quality of broccoli.The whole process of cold chain process is as follows:place of origin ? precooling(0?;12h)? packaging(Delivery temperature:0.2?)?refrigerated shipment((4 ± 2)?;42h)? cold storage ?outbound loading ? dispatching ? selling((4 ± 2)?).The impact of whether the entire cold chain process include pre-cooling,refrigerated shipment,and the temperature at selling stage,on the sensory quality,chlorophyll content,ascorbic acid content,and weight loss rate of broccoli.Results showed that the broccoli with complete cold-chain would better reduce the weight loss rate of the flower bulb(p<0.01),and maintain the nutritional value of the flower bulb resulting in the increase of the commercial value of broccoli.In the case of a complete cold chain of broccoli,it could extend the shelf life of flower bulbs to the 6th day;Also,flower bud yellowing,flowering,dehydration and wilting would not occur until the 6th day.However,broccoli,which presented in incomplete cold chain,lost its commercial value on the 4th or 5th day.Therefore,it is important to guarantee the complete cold chain for broccoli to prolong its shelf life.2.The effects of different packaging methods on the quality of broccoli on sale.The effects of different packaging methods on weight loss rate,anthocyanin content,moisture content and sensory quality of broccoli during the marketing process,which were under the environmental condition of(4±0.5)?,and(90%±5%)relative humidity,were studied.The results showed that all indicators of samples from PE film(0.5mm)packaging group and skin packaging group were significantly better than those of group used PE film packaging with 4 holes(0.22mm in diameter);and the samples from skin packaging group was better than those from the PE packaging group.Therefore the skin packing could better maintain the sale quality and commodity value of broccoli.3.The process of complete cold chain and production specifications of broccoli.The process of complete cold chain of broccoli was improved through experiments,literature review and field research.The critical control points of the process of complete cold chain of broccoli were identified as raw material acceptance,transportation and distribution.And also the critical limits of critical control points were clarified as following:The pre-cooling temperature should be 0?,the storage temperature should be(-1±0.5)?,Pre-cooling time is 8h,the refrigerated transportation and distribution temperature should be(4±2)?,the selling temperature should be(4±2)?.