Formation And Changes Of Characteristic Aroma Compounds In Lentinula Edodes During Hot Air Drying And Storage Process

The volatile components of fresh,hot air dried and stored Lentinula edodes were analyzed by solid-phase microextraction gas chromatography mass spectrometry.The odor of each Lentinula edodes sample was distinguished by electronic nose.The key aroma compounds of fresh and hot air dried Lentinula edodes were screened by the four following methods:Detection frequency,Time-intensity,Flavor profile analysis and Odor activity value.Meanwhile,the relationship between sulfur compounds and the enzyme activities of GGT and C-S lyase in hot air dried Lentinula edodes was discussed.In addition,the connection between the content of key aroma compounds in Lentinula edodes and the enzyme activity of GGT and C-S lyase under different storage temperatures were measured.The main results were as follows:（1）The main aroma characteristic in early stage of hot air drying process in Lentinula edodes was mushroom flavor（3-octanone,1-octen-3-one,1-octen-3-ol）.A pungent smell of sulfur stink arised in the middle stage of hot air drying process and the flavor of oil or flower/sweet was primary attributed to the last stage of hot air drying process.（2）The key aroma compounds with higher content in fresh Lentinula edodes were3-octanone（543.97±89.64 ng/g）,1-octen-3-one（293.16±35.77 ng/g）,1-octen-3-ol（140.08±7.79 ng/g）.The highest content was 1-octen-3-ol（327.69±83.87 ng/g）after three hours’hot air drying.When at sixth hours,the content of dimethyl disulfide,dimethyl trisulfide was 2463.78±442.04 ng/g and 631.71±22.17 ng/g,which was the maximun content of the whole process.As for ninth hours,the content of carbon disulphide and dimethyl disulfide were nearly the same.At the later stage of drying,3-octanone,octanol,1-octen-3-ol were not detected.Lentinula edodes storaged at 10℃、25℃、37℃for fifty days,the results showed that aroma components could be kept well at 10℃,and it changed slowly in storage at 25℃.The content of aldehydes increased gradually with the prolonging of storage time at 37℃.（3）Electronic nose was used to collect the fingerprint informations about dried and stored Lentinula edodes.The results indicated that the trend of clustering between different hot air drying time and storage samples were obvious,and the discriminant factor analysis showed that cumulative contribution rate of the first and second discriminant factor was greater than 95%,which could be effectively distinguished for different Lentinula edodes samples.（4）The enzyme activity of GGT and C-S lyase decreased first,then increased and then decreased with the prolonging of drying time.The content of sulfide increased first and then decreased during drying process,and reached the maximum at 6 h.Throughout the whole drying process,volatile C₈ compounds were consistent with the changes of linoleic acid content and the enzyme activity of LOX,which could infer that there had some correlation among the three compounds.The sulfide content and enzyme activity of GGT were decreased then increased and decreased again during storage at 10℃,the trend of enzyme activity of C-S lyase decreased first and then increased.Negative correlation was found with the changes of sulfide content after 7 d.In the 25℃storage,the trend of sulfide content decreased first,then increased and then decreased.GGT enzyme activity went up first and then went down.The trend of enzyme activity of C-S lyase during the whole storage period was firstly decreased and then increased,and after 7d,it was negatively correlated with the trend of sulfide content.When the storage temperature was 37℃,the content of sulfur compounds decreased gradually under the storage condition.The enzyme activity of GGT and C-S lyase were negatively correlated with the change trend of sulfide content at 7 d and 20 d.