Studies On Preservation And Mechanism Of Fresh-cut Broccoli

In order to find an efficient and environment friendly method to preserve fresh-cut broccoli, this paper explored the preservation effect of fresh-cut broccoli from three aspects: the anti-staling agent, storage temperature and packaging material. In order to study the effect of ethanol treatment on broccoli during storage, the polyphenol monomers composition and content were analyzed as well as group of metabolism during storage of fresh cut broccoli was studied. This research will provide a reference for other similar future studies with different products. The main research results were as follows:1. Three different volume fraction of ethanol solution(10 %, 20 % and 30 %) were used to treat the fresh-cut broccoli for 2 min and then stored at 4 ℃. The investigation of quality and microbiological index of fresh-cut broccoli by ethanol treatment was showed that 20 % ethanol treatment could maintain the texture, delay the nutrients loss, restrain the activity of PPO and PAL, effectively improve the storage quality and extend the shelf life of fresh-cut broccoli.2. 20 % ethanol solution and distilled water were used to treat the fresh-cut broccoli for 2 min and stored at three different temperatures(4 ℃, 7 ℃ and 10 ℃) respectively and the investigation of quality and microbiological index of fresh-cut broccoli during storage were tested. The result showed that control group and ethanol treatment group stored at 4 ℃were better than that of 7 ℃ and 10 ℃, and the combination of 4 ℃ storage and 20 % ethanol treatment can control the section browning and extend the shelf life more effectively.3. Using 20 % ethanol solution to treat the fresh-cut broccoli for 2 min, and then used four different packaging bags for fresh cut broccoli storage. After sealed the packaging bags,the fresh-cut broccoli were stored at 4 ℃. The determination and analysis of water vapor transmission rate, gas transmission rate and fresh keeping effect of various packaging materials showed that Glad double lock bag is more suitable for packaging fresh-cut broccoli. higher water vapor transmission rate and gas transmission rate during storage may be due to water loss through packaging bags, this phenomenon may also cause yellowish or even moldy appearance may lead to CO2 injury.4. The separation conditions of chromatography were optimized with a reversed-phase high performance liquid chromatographic method for the determination of eleven polyphenols in tender stems of fresh-cut broccoli. The relationship between composition and flow rate of mobile phase were discussed respectively. Then the influence of gradient separation conditions was established. Broccoli extracts of phenolic compounds were quantitatively analyzed. nine out of eleven kinds of polyphenols were detected. Comparing the content of coumaric acid and cinnamic acid in the control group and the ethanol treatment group, it can be speculated that ethanol treatment can maintain PAL and C4 H enzyme activity, inhibit the activity of PPO enzyme.5. GC-MS-based metabolic profiling approach was used to identify metabolome changes in fresh-cut broccoli during storage. The metabolic network was constructed by detecting and analyzing the majority metabolites. A total of 339 peaks were detected, and screen 23 out of 339 metabolites, such as 3 sugars, 12 kinds of amino acids and 7 kinds of organic acids etc. The major metabolic pathways influenced by ethanol processing of fresh cut broccoli were constructed, such as: sugar metabolism pathway, tricarboxylic acid(TCA) cycle and amino acid metabolism pathways.