Study On Partial-freezing Characteristics And Technology Of Purple Cabbage

As a kind of vegetable that consumers love,During the storage period,there are some problems such as short shelf life,water loss and perishability This paper studies the partial-freezing characteristics and process of fresh-cut purple cabbage and has done three aspects in details.It studies the cold processing pretreatment process of fresh cut purple cabbage and explores the partial-freezing quality characteristics and variation of fresh-cut purple cabbage,optimizes the process conditions of fresh-cut purple cabbage storage.The main test results are as follows:First,in this experiment,the leaf weight of 1.5-2.0kg purple cabbage was used,the sensory evaluation and hardness of fresh-cut purple cabbage were used as evaluation indexes.The optimal level of each factor was determined on the basis of single factor experiment,the effects of different concentrations of brittle preservatives,different soaking times of brittle preservatives and different ratios of liquid to fresh purple cabbage were studied by orthogonal test.The optimum process of cold processing pretreatment of fresh-cut purple cabbage was obtained by the range and variance analysis of orthogonal test: the concentration of the preservative CaCl₂solution was 0.5%,the soaking time was 5 min and the ratio of material to liquid was 1:15.Second,the freezing law of fresh-cut purple cabbage at various temperatures was studied by determination of freezing curve of fresh-cut purple cabbage at different freezing temperatures and determines that the partial-freezing temperature of the subsequent test is-2°C.Then,the micro-frozen adaptability analysis of fresh-cut purple cabbage was carried out.The test data shows that whether it is under partial-frozen or refrigerated conditions,with the prolongation of storage time,the sensory score,color,texture（hardness,elasticity,chewiness）of fresh-cut purple cabbage shows a downward trend.The water loss rate,microbial indicators,and rot rate are on the rise;The anthocyanin content first increase and then decrease.However,the quality change of fresh-cut purple cabbage under partial-frozen conditions is slower than that under cold storage conditions.And the difference in quality of fresh-cut purple cabbage was not obvious when refrigerated for 21 days and for 42 days.Therefore,partial-freezing can inhibit the water loss,decay and browning of fresh-cut purple cabbage significantly.It can also reduce the growth rate of microorganisms and effectively maintain the hardness,elasticity,chewiness and sensory quality of purple cabbage,reduce the loss of nutrients such as anthocyanins and prolong the shelf life.It is concluded that the fresh-cut purple cabbage has the feasibility of using partial-frozen storage and preservation technology.Third,on the basis of single factor experiment,the best preservation process of freshly cut purple cabbage was carried out by variance and range analysis: the partial-freezing storage temperature was-3°C,the slice size was 30mm×40mm,and the freezing rate was 2.79cm/h.After thawing,the fresh-cut purple cabbage blue color is normal,the smell is fragrant,no rot,the taste is light and refresh,the juice loss rate is only 1.1% and all indexes are ideal.