Rapid In-Field Volatile Sampling for Detection of Infection in Wine Grapes.

Fungal infection of grape berries () by frequently coincides with harvest, impacting both the yield and quality of grape and wine products. A rapid and non-destructive method for identifying infection in grapes at an early stage prior to harvest is critical to manage loss. In this study, zeolitic imidazolate framework-8 (ZIF-8) crystal was applied as an absorbent material for volatile extraction from infected and healthy grapes in a vineyard, followed by thermal desorption gas chromatography-mass spectrometry. The performance of ZIF-8 in regard to absorbing and trapping the targeted volatiles was evaluated with a standard solution of compounds and with a whole bunch of grapes enclosed in a glass container to maintain standard sampling conditions. The results from the sampling methods were then correlated to infection in grapes, as measured and determined by genus-specific antigen quantification. Trace levels of targeted compounds reported as markers of grape infection were successfully detected with in-field sampling. The peak area counts for volatiles 3-octanone, 1-octen-3-one, 3-octanol, and 1-octen-3-ol extracted using ZIF-8 were significantly higher than values achieved using Tenax-TA from field testing and demonstrated good correlation with infection severities determined by antigen detection.