| Broccoli is an edible green vegetable of its large flower head, and is very popular with its high nutritional value, ranking first in the cabbage family, which is known as "vegetable crown". However, broccoli deteriorates very quickly after harvest at ambient due to the loss of green color and the consequent yellowing of florets, let alone the fresh-cut one, which severely limits the industrial and commercial development of fresh-cut produces. Currently, the standard practice to control postharvest yellowing of fresh-cut broccoli worldwide is to refrigerate the vegetables after harvest, but we are lack of fresh-cut fruit and vegetable management system operating mode, and sophisticated storage transport technologies. Therefore, to find new safe and effective preservation methods is very necessary. In this paper, fresh-cut broccoli (Chaoda No.1) was used to investigate the preservation effect of ethanol pretreatment and the possible mechanisms from anti-oxidation, glucose metabolism and, etc. Then, we studied the influence of different blanching time on fresh-cut broccoli active compounds, in order to find the optimal processing time for the family cooking. The results are as follows:1. The effect of ethanol vapor pretreatment (100,250,500 or 1000 μL/L) on the shelf life of fresh-cut broccoli was investigated. The results showed that pre-treatment with 500μL/L of ethanol significantly prolonged the shelf life of fresh-cut broccoli up to 12d. 500 μL/L ethanol inhibited the increase of the color parameters L* value, and the decrease of H, and the degradation of chlorophyll content. Compared with the control, ethanol vapor was more effective in maintaining the nutritional ingredient of glucosinolates and sulforaphane. Meanwhile,500μL/L ethanol had significant effect on holding a high level of glucose, sucrose and fructose. As a result, fresh-cut broccoli visual and inner quality was maintained by 500 μL/L ethanol vapor.2. Significant effects on antioxidant systems of fresh-cut broccoli were determined in 500μ/L ethanol vapor treatment, including an increase of antioxidant related substances total phenolics, total flavonoids and the activity of antioxidant-related enzymes SOD, APX, CAT. The mechanism for ethanol vapor treatment to delay senescence was related to the improving of antioxidant activity to enhance free radical scavenging capacity of Super oxide anion radical, Hydroxyl radical, DPPH radical and reducing activity, and reduce the accumulation of MDA.resulted in significantly lower decay rate. These results indicated that the control of senescence is directly because of the inhibit of ethanol vapor, and indirectly because of improving of antioxidant activity, maintain the balance between the formation and detoxification of activity oxygen species, delay the lipid peroxidation process.3. The effects of ethanol pretreatment on antioxidant compounds in fresh-cut broccoli florets during different blanching time (1,2,3,4,5min) was investigated. Studies have shown that ethanol pretreatment inhibits the reduction of chlorophyll, total phenol, total flavonoids, total glucosinolates, sulforaphane and soluble sugar content in different time blanching process, which maybe result from ethanol that could maintain the integrity of the cell wall, and it plays the similar role in the latter blanching process Throughout the process,1 min blanching time was regard to greatly maintain nutritional content of broccoli. These results suggest that blanching may enhance antioxidant compounds in broccoli florets though the priming. |
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