Bruise And Chilling Injury Detection Of "Xiahui5" Peach By E-nose

Peaches are very popular with consumers for its delicacy, sweet-smelling, as well as good for nutrition. Tender and juicy texture make peaches sensitive to external forces during harvesting and transporting; Peaches ripen and deteriorate quickly at ambient temperature, keep in low temperature could slow these processes. Howerver, conditions of cold storage which is not propriate will cause chilling injury. Peaches always have normal looks in the first stage of bruise or chilling injury, in order to avoid bigger loss and to protect consumer’s rights and interests, detecting bruise and chilling injury before storage and selling is needed. Detection of ’Xiahui5’ peach bruise and chilling injury by e-nose is researched in this paper, solid phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS) were used to analyze the flavor of affected peach.1. Detection of peach bruise by e-nosePeaches were impacted by external forces to cause different size of bruise, and then the e-nose was used to evaluate the flavor of the affected fruits. Principal Component Analysis (PCA) of sensor responses could distinguish fruits with different size of bruise. Correlation analysis showed that S5、S6、S7、S10played the major role in the distinction. Both models based on multiple linear regression (MLR) and Fisher linear discriminant analysis can pass the significance test. Fisher linear discriminant model’s accuracy was96.7%, and it is5percent higher than that of MLR. Flavor analyze by SPME and GC-MS showed that both grass-type and fruit-type flavor’s relative content increased along with the increase of bruise level, and the former’s growth rate is greater than that of the later. Styrene, E-2-hexene acetate and isoprene were found in affected fruits only, and their relative contents increased along with the rise of bruise level, means that they may be the character gas of peach with bruise.2. Quality change during cold storageChanges of sensory evaluation score, browning index, total soluble solids, titratable acid, extractable juice rate and hardness of peach during cold storage were measured. Determination of the chilling injury classification standard is as follows:peaches without browning and scored above90are grade0; peaches with slight browning, scored80between90and could soften as normal are grade1; peaches which look normal while flesh brown severely, scored from70to80and wouldn’t soften as normal are grade2; peaches that all flesh was brown, scored less than70and wrinkled are grade3.3. Detection of peach chilling injury by e-noseE-nose was used to evaluate the flavor of fruits during cold storage. PCA of sensor responses could distinguish fruits with different level of chilling injury. Loading and correlation analysis showed that S5、S6、S7、S10played the major role in the distinction. Both models based on MLR and Fisher linear discriminant analysis can pass the significance test. Fisher linear discriminant model’s accuracy was91.7%, and it is10percent higher than that of MLR. Flavor analyze by SPME and GC-MS showed that grass-type flavor’s relative content increased along with the rise of chilling injury level, and fruit-type flavor’s relative content decreased along with the rise of bruise level. Tetradecane, Hexadecane and nonadecane were only found in peaches with chilling injury, and their relative contents increased along with storage time, indicates they may be the character gas of peach with chilling injury.