Abstract：Grapes vaporize volatiles in specific compositions and concentrations during deterioration processes. Our previous study demonstrated that it is possible to analyze grapes spoilage stages by using the infrared spectra of their volatiles. However, only the spectral characteristics of alcohol, ethyl acetate and carbon dioxide were observed in the experiment because of the low concentration of the volatiles. In this paper, the sensitivity of the spectrometry system was enhanced by increasing the optical-path with multi-reflecting mirrors. We used the new spectrometry system to study the details of the infrared spectra of the volatiles from grapes during spoilage, and observed the spectral characteristics of several kinds of ethanol, esters, aldehyde and ethylene. The concentrations of some components in the volatiles changes with storage time, which can be a biomarker to represent the spoilage stages of grapes. Chemometrics were used to analyze the spectral bands of ethanol and esters, demonstrating there are obvious differences between fresh and decayed grapes. Furthermore, we developed a simplified E-nose system comprised by sensor array, based on the results of spectral analysis. The classification and discrimination of grape spoilage were tested with E-nose. This was a further study of the previous publication and had given a more precise observation of the infrared spectral characteristics of the volatiles from decayed grapes. This study provided a basis for developing real-time monitoring techniques of fruits deterioration.
[1] Hui Y H. Handbook of Fruit and Vegetable Flavors. Wiley, 2010. 64. [2] Romani R, Labavitch J, Yamashita T, et al. Journal American Society for Horticultural Science 1983, 108(6): 1046. [3] Mattheis J P, Buchanan D A, Fellman J K. Journal of Agricultural and Food Chemistry, 1991, 39(9): 1602. [4] Boylston T D, Kupferman E M, Foss J, et al. Journal of Food Quality, 1994, 17: 477. [5] Maul F, Sargent S A, Balaban M O, et al. Journal of the American Society for Horticultural Science 1998, 123(6): 1094. [6] Schnürer J, Brjesson, Thomas J O. Fungal Genetics and Biology, 1999, 27(2): 209. [7] Baldwin E A, Malundo T, Bender R, et al. Hort Science 1999, 34(3): 514. [8] Charalambous G, Inglett G. Chemistry of Foods and Beverages: Recent Developments. Academy Press Inc., 1982. 25. [9] Baldwin E A. Fruit Quality and Its Biological Basis. Sheffield: Sheffield Academic Press, 2002. 89. [10] Li C, Schmidt N E, Gitaitis R. LWT Food Science and Technology, 2011, 44: 1019. [11] Keshri G, Magan N, Voysey P. Letters in Applied Microbiology, 1998, 27: 261. [12] Li C, Gitaitis R, Tollner B, et al. Sensing and Instrumentation for Food Quality and Safety, 2009, 3: 193. [13] Gobbi E, Falasconi M, Concina I, et al. Food Control, 2010, 21(10): 1374. [14] Griffiths P, De Haseth J A. Fourier Transform Infrared Spectrometry, John Wiley & Sons, 2007. 171. [15] Marshall T L, Chaffin C T, Hammaker R M, et al. Environmental Science & Technology 1994, 28(5): 224A. [16] Ross K R, Todd L A. Applied Occupational and Environmental Hygiene, 2002, 17(2): 131. [17] Harren F J M, Cristescu S M. AoB Plants, 2013, 5: plt003. [18] WANG Wen-zhong, DONG Da-ming, ZHENG Wen-gang, et al(王文重，董大明，郑文刚，等). Acta Chimica Sinica(化学学报), 2013, 3: 99. [19] Lias S G, Bartmess J E, Leibman J F, et al. National Institute of Standards and Technology. Gaithersburg MD, 2003, 20899. [20] Whitaker R, Evans D. Food Technol., 1987, 46: 86. [21] Rosilllo L, Salinas M, Garijo J. Journal of Chromatography A, 1999, 847(1): 155. [22] Bellincontro A, Nicoletti I, Valentini M, et al. American Journal of Enology and Viticulture, 2009, 60: 57. [23] P, G. Pratical Guide to Chemometrics; CRC Press, Taylor & Francis Group LLC, 2006.
