Odor Composition Of Pterocarpus Macarocarpus Kurz Heartwood And Its Releasing Mechanism Research

This thesis studied on Pterocarpus macarocarpus Kurz heartwood.Firstly,the odor composition of this wood was analyzed,meanwhile those organic compounds contained inthis wood was extracted sufficiently,in order to reveal the essence ofPterocarpus macarocarpus Kurz heartwoododor,evaluatehealthcare function of the odor and sought relationship between odor and extractives.Secondly,effects of different influence factors（temperature,time,the sample surface airflow,sample particle size,drying methods）on the releasingbehavior of Pterocarpus macarocarpus Kurz heartwood odor were reseached,in order to obtain odorreleasing discipline,and the change ruleof odor composition and released amount.Thirdly,by analyzing the microstructure of Pterocarpus macarocarpus Kurz heartwood,researching the mass transfer power and mechanism of released odor,the modelof odor mass transfer and releasing was established.Subsequently,by researching the calculating method of releasing characteristic parameter,combined with the experiment which woododor release in enclosed space,the odor releasing characteristic parameters of Pterocarpus macarocarpus Kurz heartwood were solved.Finally,the odor releasing prediction model which base on mass transfer and release mechanism was established.Subsequently,the corresponding relations between rheology theory and wood odor releasing behavior was researched,and the odor releasing prediction model which base on rheology theory was established from a macro perspective.Then these two odor releasing prediction models were verified according to odor long-term releasing experiment,and were compared and used in evaluating odor releasing behavior in the future.After theseresearch,some conclusions can be achieved as below:（1）14 sesquiterpenes could be identified from the Pterocarpus macarocarpus Kurz heartwood odor released under normal temperature.They are respectively copaene（0.49%）,β-Elemene（0.67%）,Longifolene（0.1%）,β-Caryophyllene（2.21%）,α-Guaiene（0.32%）,1,4,7,-Cycloundecatriene,1,5,9,9-tetramethyl-,Z,Z,Z-（4.4%）;γ-selinene（17.54%）,α-Gurjunene（1.5%）,β-selinene（16.36%）,（-）-α-Selinene（0.85%）,Eremophilene（1.1%）,Machilol（3.5%）,β-Eudesmol（34.99%）and1H-Cyclopropa[a]naphthalene,1a,2,3,3a,4,5,6,7b-octahydro-1,1,3a,7-tetramethyl-,[1aR-（1a.α.,3a.α.,7b.α.）]-（13.91%）.Some studies have shown that the healthcare ingredients in wood volatiles are mainly monoterpenes and sesquiterpenoids,which amount can be used as an index to assess the healthcare value of wood odor.The content of sesquiterpenes in odor released from Pterocarpus macarocarpus Kurz heartwood under normal temperature achieved 97.94%according to area normalization method.Thus,this wood odor has value and potential for human health care.（2）Pterocarpus macarocarpus Kurz heartwood odor mainly derive from which extractives.And temperature has great influence on the odor release:（1）When temperature is lower than 80°C,the odor comes mainly from the wood extractives;（2）When temperature is is between 80°C and 120°C,the decomposition of wood begins to make contribution to the volatiles,in addition to volatilization of the extractives,and the odor components become more complex;（3）When temperature is above 120°C,the decomposition of wood is accelerated,and a large amount of aldehydes,phenols and acids,etc.are released.When temperature is lower than 60°C,the terpene releasing speed approached to constant along with time extension.When temperature is over 80°C,the terpene releasing speed increased continuously.According to this phenomenon,it could be speculated that some organic component in Pterocarpus macarocarpus Kurz heartwood could happen decomposition or reaction,so as to generate a new terpenes under higher temperature,as heating time is prolonged.（3）The odor amount and composition varietiesof Pterocarpus macarocarpus Kurz heartwood increased constantly with temperature rising,homoplastically the released amount and varieties of sesquiterpenoids also increased gradually with temperature rising.But when the temperature was over 100℃,the amount of sesquiterpenoids begin to reduce,and the relative percentage of sesquiterpenoids had a downward trend with the temperature increase.Therefore,the higher temperature can stimulate Pterocarpus macarocarpus Kurz heartwood to release more sesquiterpenoids with healthcare function.But at the same time,the released amount of other compounds which may endanger human health increase more than the amount of sesquiterpenoids.Meanwhile,the odorcomposition released at higher temperature is more complicated.That is to say,the wood odor released under high temperature has certain risk to human health.Therefore,it is safer to enjoy the aroma released form Pterocarpus macarocarpus Kurz heartwood at ambient temperature.（4）Sample grain size and surface airflow have no impact on the released odor composition,but will effect the odor amount.The smaller grain size,the moreodor could be released,and the faster surface airflow,the more odor could be released.But the overall impact by sample grain size and surface airflow is limited,and the increasing trend of odor release will wear offgradually.（5）Vacuum freeze drying（VFD）,vacuum drying（VD）and conventional drying（CD）method were investigated in this thesis.Regarding the drying process,VFD method has better performance over CD and VD methods in preserving the physiologically valuable ingredients and total mass of extractives in Pterocarpus macarocarpus Kurz heartwood.Similarly,VFD method is also most beneficial to preserve more content and composition of this wood odor.（6）After amending and analyzingone-dimensional model of odor releasing,the calculation method was obtained,which is used to solve odor releasing characteristic parameter of Pterocarpus macarocarpus Kurz heartwood.After that,the confined space experiment was carried out,the odor releasing characteristic parameterswere:D_kj=7.267×10^-3m/h;K=1.403×10⁵;C₀=617.443ug/m³.（7）According to the mass transfer mechanism and odor releasing characteristic parameters ofPterocarpus macarocarpus Kurz heartwood,the mechanism prediction model was established as C_st=0.2151e^{-1.6613×10-5t}-0.2151e^-1.0392t.From a more macro perspective,combined with rheology theory and the odor releasingexperimentfor long-term,therheologypredictionmodelofreleasedodorwasestablishedas C_st=0.2136e^{-1.3946×10-5t}-0.1286e^-0.9984t.That mechanism prediction model ismore suitable to get the odor releasing behavior in short period,and the rheology prediction model can provide more precise releasing result for long-term.（8）According to the mechanism prediction model and rheology prediction model,the odor releasing process could be summarized three stages as follow:（1）quick releasing stage,which is mainly in 10 years;（2）time-lapse releasing stage,which is about 10-30years;（3）steady releasing stage,which is about 30 years later.