| Pleurotus geesteranus is a kind of precious edible fungi,which is widely distributed in our country and its yield is increasing rapidly.Pleurotus geesteranus is a typical food material with characteristics of high protein,fiber,trace elements,but low fat,and it contains some substances with anticancer and antioxidant activities,such as polysaccharides and flavonoids.Pleurotus geesteranus is easily spoilaged under normal tempreture for the high level of respiratory climacteric coupled with their high moisture content and fruitbody aging rapidly.Pleurotus geesteranus preservation period of storage under normal temperature for 2-4 d.Therefore,to improve the storage period of Pleurotus geesteranus,not only have theoretical significance,but also application prospect.It can provide a scientific basis for Pleurotus geesteranus storage and processing,and promote the rapid development of Pleurotus geesteranus industry.Different temperature treatment effect on quality,physiological and biochemical changes,taste and volatile components of Pleurotus geesteranus during storage was determined,and the main results are as follows:During the storage at 20?,the sensory quality decreased rapidly,the soluble sugar and soluble protein content were decreased at 2-3 days of Pleurotus geesteranus.The storage time was only 3 days.Compared with 20 ?,the decrease of sensory quality,and the increase of metabolic rate of respiration and ethylene producion was reduced at 0?,5?,10?.Pleurotus geesteranus can be stored at 10? for 12 days,and after 12 days of storage remains in good condition during the storage at 0?,5?.The determination of free nucleotides has been studied.A method for simultaneous determination of 6 nucleotides by high performance liquid chromatography was established,the optimum concentration and pH of the mobile phase is 0.1 M KH2PO4(pH = 4.20).Total free amino acid content of Pleurotus geesteranus showed an increasing trend,flavor amino acids up to 4.74mg/g,and flavor 5'-nucleotides reached 0.27mg/g during the storage period at 0 ?,5 ?,10? and 20 ?.During the storage at 0? and 5 ?,the content of umami amino acids,sweet amino acids and bitter amino acids was uniformly growing.During 10?,20? storage,umami amino acids and bitter amino acid content increased first and then decreased,sweet amino acid content has been growing.The determination results of taste of Pleurotus geesteranus by electronic tongue showed that the intensity of sweetness and sourness decreased with the extension of storage time,and the intensity of bitterness,flavor,and saltiness increased.Fresh Pleurotus geesteranus has very delicate aroma,including hexanal,3-octanone,2-pentyl furan,3-octanol,palmitic acid,linoleic acid and other components by SDE.And the relative contents of acids and alcohols increased first and then decreased,alkanes and alkenes showed a downward trend,while the relative content of ketones showed an upward trend during storage period.The energy metabolism and critical related enzymes activity were determined,the results showed that the level of cell's energy supply is different with different storage temperature.Pleurotus geesteranus energy has been declining during 20 ? storage.During 10 ? storage period,the energy decreased rapidly in 6 days after storage,the changes of energy is slow during 0?.The activity of H+-ATPase,Ca2+-ATPase and SDH were decreased after 1 days storage,and CCO activity decreased rapidly after 2 days storage during 20 ? storage period.Low temperature storage reduced activity of related energy metabolism enzymes,and slowing down the energy consumption of cells,thereby prolonged the storage time of Pleurotus geesteranus. |
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