Study On De-astringency, Crispness-keeping And Browning-preventing Regulation Mechanism And Its Nondestructive Measurement Technique Of Mopan Persimmon

Mopan persimmon (Disopyos Kaki L.) originated in our country is one of the major varieties of astringent persimmon lines. De-astringency, crispness-keeping and browning-preventing have been anxious to resolve posthavest storage technique bottleneck. Although there are many reports about above questions, and yet most opinions fastened on simplification technique or physiological researches, such as maturity, temperature, high CO2, ethylene, correlation emzyme and substrate, and etc. Presently, the relationship between these indexes and their interactions have not been compressively elucidated yet, and effective regulation mechanism and its nondestructive measurement technique of fruit de-astringency, crispness-keeping and browning have studied rarely.The key technique parameter of Mopan persimmon posthavest de-astringecy was ascertained. In this paper, regulation effect and correlation mechanism of CO2, vaccum packaging, liquid storage.1-MCP treatment, common cold storage, hypobaric storage, controlled freezing point storage and integration technique on fruit were studied, and nondestructive models and precision forecast of de-astringency(soluble tannin content), crispness-keeping and quality(firmness and TSS), and browning indexes(peel color and flesh turbidity) in Mopan persimmon by near-infrared diffuse reflectance spectra, and feasibility of nondestructive measurement these indexes were discussed. Research results were as follows:1. The CO2 whole de-astringent condition was ambient temperature of 25℃, CO2 concentration of 90% and de-astringent time of 24 h. The CO2 de-astringent of two stage method was ambient temperature from 18 to 20℃, packaging of plastic net and placement 24 h after 90% CO2 de-astringent 24 h. The vaccum packaging de-astringent condition was ambient temperature from 18 to 20℃, vaccum degree of 0.08 MPa and de-astringent time of 10 d. The de-astringent time of eight degree ripeness fruit with vaccum packaging was 14 d under ambient temperature, which was 45 d under low temperature and turned color easily. The de-astringent time of fruit with 2% NaCl liquid stroge was 45 d under contolled freezing point storage.2.1-MCP treatment postponed the decrease of fruit firmness and soluble tannin effectively, controlled the increase of fruit respiration intensity and ethylene production, delayed the peak time of fruit respiration intensity and ethylene production, restrained rise of later storage fruit MDA and membrance relative conductance, deferred fruit ripe and senescence process, and improved increase of PG, Cx and amylase activity, deferred fruit softening process, but has no effect on PE activity during ambient and low temperature. Fruit softening influence factors from big to small was PG, Cx, amylase, PE. 3. Hypobaric cold storage, contolled freezing point storage and 1-MCP combined with contolled freezing point storage could control the decrease of fruit firmness, Vc and TA content, delayed the hoist of TSS, delayed the increase of respiration intensity and ethylene production, restrained later storge MDA. membrance relative conductance and PPO activity, controlled the decline of total phenol, SOD activity and former storage POD activity. Mopan persimmon storage time with hypobaric cold storage extended about 30 d, fruit storage time with contolled freezing point storage extended 45 d upwards, fruit storage time with 1-MCP combined with contolled freezing point storage extended 60 d upwards.4. Soluble tannin model used MPLS, second derivative and DET treatment to establish calibration model and to predict, and Rcv was 0.8754, RMSECV was 0.0936, Rp2 was 0.825, RMSEP was 0.1116, RPD was 2.33. Firmness model used MPLS, first derivative and None treatment to creat calibration model and to predict, and Rcv was 0.9507, RMSECV was 1.1421. Rp2 was 0.952, RMSEP was 1.3303, RPD was 4.55. TSS model used MPLS, first derivative and DET treatment to creat calibration model and to predict, and Rcv was 0.8420, RMSECV was 0.3857, Rp2 was 0.836, RMSEP was 0.3636, RPD was 3.30. Therefore, the preliminary research on the built models indicated that nondestructive measurement of the fruit soluble tannin content, firmness and TSS using VIS/NIR spectroscopy technique was feasible.Three indexes comprehensive model used MPLS, first derivative and None treatment to establish calibration model and to predict, but the model precision declined to some extent, could only proceed quantitative analysis roughly, the precision of the models could be improved further.5. L model used MPLS, original spectra and None treatment to establish calibration model and to predict, and Rcv was 0.9774, RMSECV was 0.8268, Rp2 was 0.959, RMSEP was 1.1120, RPD was 5.09. a* model used MPLS, first derivative and None treatment to establish calibration model and to predict, and Rcv was 0.9896, RMSECV was 0.5503, Rp2 was 0.985, RMSEP was 0.5859. RPD was 11.38. b* model used MPLS, original spectra and None treatment to establish calibration model and to predict, and Rcv was 0.9788, RMSECV was 1.3775, Rp2 was 0.968, RMSEP was 1.4177, RPD was 7.92. Three models had good predicted result. Three indexes comprehensive model used MPLS, first derivative and None treatment to establish calibration model and to predict, but the model precision declined to some extent, but its RMSECV and RMSEP was above 0.9, RPD was above 3.0, this model had good applicability. Flesh turbidity model used PLS, original spectra and None treatment to establish calibration model and to predict, and Rcv was 0.7766, RMSECV was 0.1143, Rp2 was 0.757, RMSEP was 0.1079, RPD was 2.22. The model could only accomplish quantitative analysis roughly. Therefore, the preliminary research on the built models indicated that nondestructive measurement of the flesh turbidity VIS/NIR spectroscopy technique was feasible, but the precision of the models could be improved further.