Methodology Study Of The Evalution Of Fruit Maruritius By Measureing The Volatile Aroma Using Electrochemical Sensors

There are few aromatic hydrocarbon gases released from immature fruits.With the ripening of fruits,more and more aromatic hydrocarbon gases are released from fruits.The conce ntrations of aromatic hydrocarbon gas released from fruits were closely related to fruit maturity.Normally,for bananas,less than 0.01% of fresh weight of fruit are associated with volatile arom atic hydrocarbon gas,and the synthesis of aromatic compounds is affected by ethylene gas,and t he ethylene gas emitted from the banana accounts for 70% of the total aromatic hydrocarbon gas.The ethylene gas released from apples conforms the same rule as that of aromatic hydrocarbon gas from apples.The concentrations of aromatic hydrocarbon gas from fruits are closely related t o fruit respiration.Different types of fruits conform the different respiration rule.Certainly,the c oncentrations of ethylene gas released from fruits are different.The more aromatic hydrocarbon r eleased from fruits,the more amount of ethylene gas are released from fruits.Ethylene gas is al so a kind of plant endogenous hormones,which plays an important role in fruit growth,develop ment,flowering,bear fruit and aging.As we know the loss of fruit industry in China is up to 30 % each year due to the mixed fruits at different maturity levels.It is of great significance to measure the aromatic hydrocarbons released from fruit and thus to determine the maturity of fruit s for fruit transportation,processing and storage.Currently,detection technology of the aromatic hydrocarbon released from fruit mainly includes both gas chromatography and electronic nose.Ho wever,the instrument based on the gas chromatography is complicated and complicated,and the instrument based on the electronic nose is expensive.They are unable to detect the aromatic hyd rocarbon online.For solving this problem existing in a real-time detection of aromatic hydrocarbo ns in fruit,this paper proposes a measurement method to detect the aromatic hydrocarbon gas rel eased from fruits using an electrochemical ethylene gas sensor,and explore the feasibility of the determination of fruit maturity levels by using the concentration of aromatic hydrocarbon gas rele ased from fruit.In this paper,two kinds of experimental setups are constructed,which are based on the embedded system and mini-board integration system,respectively.The experimental setup is composed of an electrochemical sensor,a micro-vacuum pump,a microcontroller,a gas tube,a glass bottle and a gas chamber.In this paper,the hardware circuit is designed to detect the a romatic hydrocarbon gas released from fruit,and two kinds of software for both hardware circuit s were compiled by C language and C# language.The detection circuit,electrochemical sensors,micro-vacuum pump and the gas chamber are integrated into the portable experiment setup constr ucted by the embedded chip system.The dimension of this setup is 200mm×300mm.The detecti on circuit of the fruit maturity designed by the mini-board integration system has a large amount space of data storage,which can be used to obtain and store the relationship curve between the concentrations of aromatic hydrocarbon gas released from fruit and the measured times.The lev els of fruit maturity were given automatically according to the concentration of aromatic hydrocar bon gas released from fruits.In this paper,the aromatic hydrocarbon gas released from fruit is enriched and then it is flo wed at a certain flow speed through the chamber attached on the electrochemical sensor.The res ponse values obtained from the electrochemical sensor by flowing the nitrogen and air at the gas flow rate of 0.5L/min over the chamber are zero.The standard concentrations of ethylene gas o f 2.99mg/L,4.99mg/L,8.01mg/L and 10mg/L were used to verify the characteristics of the electr ochemical sensor.The correlation coefficient R square of 0.99814 and the minimum detection lim it of 0.86mg/L were calculated.The aromatic hydrocarbon gases released from apple,kiwi and p ear are detected by this electrochemical sensor system.The average concentrations of 5.29mg/L,1.38mg/L and 0.45mg/L were obtained after the enrichment device was used.The maximum relat ive deviations of 0.3mg/L,0.59mg/L and 0.27mg/L were calculated,respectively.The experiment results found that the concentration of aromatic hydrocarbon gas in immature green apple is zero.Thus,the apple maturity is possibly divided into three levels according to the measurement resu lts.For apples,it is immature when the concentration of aromatic hydrocarbon gas is lower than 1mg/L.However,the apples are mature when the concentration of aromatic hydrocarbon gas is 1~6mg/L.Moreover,it is too mature when the concentration is higher than 6mg/L.On the other hand,the concentration of ethylene gas released from fruits is related to fruit size,shape,sugar content and acidity.In this paper,the principal component analysis(PCA)algorithm is used to reduce the dimension of the measurement results of Fuji apples.The Fisher method can be used to analyze the maturity of Fuji apples.From the results,it shows that it can be clearly distingu ished due to the small cross area.This method constructed by using the electrochemical sensor i s a new way to evaluate the fruit maturity by detecting the concentration of aromatic hydrocarbo n gases released from fruit.And this evaluation method can give an instruction to protect the fru it quality in fruit processing,transportation and storage,so as to reduce the loss caused by the d eterioration of fruit.