# Rapid In-Field Volatile Sampling for Detection of _Botrytis cinerea_ Infection in Wine Grapes
###### Abstract  
Fungal infection of grape berries (_Vitis vinifera_) by _Botrytis cinerea_ frequently coincides with harvest, impacting both the yield and quality of grape and wine products. A rapid and non-destructive method for identifying _B. cinerea_ 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 _B. cinerea_ 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 _B. cinerea_ infection in grapes, as measured and determined by genus-specific antigen quantification. Trace levels of targeted compounds reported as markers of grape _B. cinerea_ 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 Tenzx(r)-TA from field testing and demonstrated good correlation with _B. cinerea_ infection severities determined by _B. cinerea_ antigen detection. quality assessment; plant disease; rapid sampling; analysis; metal-organic frameworks; thermal desorption GC-MS; VOCs 2023285227202328522720232852272023285227202328522720232852272023285227202328  
to decide when, or even if, to harvest. A rapid sampling and analytical method that can also be applied to monitor susceptible horticultural crops at post-harvest storage and transport stages may also assist in quality assurance of the supply chain. Volatile metabolomes associated with _B. cinerea_ infections have recently been used to establish the severity level of infection in wine grapes [4; 5]. Volatile compounds elicited during fungal growth vary according to abiotic conditions, including nutrient availability, temperature, microbial interactions, and substrate [6; 7]. Several volatile compounds have been selected as markers for _B. cinerea_, including 1-octen-3-ol, 1-octen-3-one, and 3-octanone, which are widely reported to cause mouldy or mushroom odours associated with fungal infections [8] and are therefore ideal targets for pathogen detection. The sensitive detection and quantification of hundreds of volatile compounds in complex mixtures using mass spectrometry (MS) is possible without sample pre-labelling. It is an excellent analytical approach for studying fungal biomarkers and wine off-flavours. The current MS analysis for grape composition frequently uses solid-phase microextraction (SPME) [9; 10] to pre-concentrate the volatile compounds directly from the sample matrix prior to analysis by gas chromatography (GC) MS [11]. Compared with distillation or solvent extraction techniques [12], the SPME method is more time efficient and can be easily automated, and the limits of detection are usually improved [13]. Nowadays, SPME is now widely used for environmental monitoring [14; 15], food and agricultural products analysis [16; 17], and drug development [18]. However, due to their high cost, fragility, and relatively small volume of solid-phase materials, SPME fibres are more suitable for lab-based experiments than field sampling. To achieve in vivo sampling and real-time monitoring of volatile compounds in grapes, alternative absorbent materials encased in robust housing that is ideal for field use are desirable. Metal-organic frameworks (MOFs) have gained considerable interest due to their enormous internal surface area (>6000 m\({}^{2}\)/g), ultrahigh porosity (up to 90% free volume), and tuneable pore size [19] and were subsequently used for a range of analytical methods and novel applications.