Stewart Postharvest Review An international journal for reviews in postharvest biology and technology © 2008 Stewart Postharvest Solutions (UK) Ltd. Online ISSN:1945-9656 www.stewartpostharvest.com Metabolomics of headspace gas for diagnosing diseases of fruits and vegetables after harvest AC Kushalappa, 1* A Vikram 1 and GSV Raghavan 2 1 Department of Plant Science, McGill University, Ste. Anne de Bellevue, QC, Canada 2 Department of Bioresource Engineering, McGill University, Ste. Anne de Bellevue, QC, Canada Abstract Purpose of review: Metabolomics is a novel biochemical tool for biological studies, including diagnosis of food contaminants and spoilage. It is a non-target approach used to detect, identify and quantify all the metabolites of an organism. With the advent of genom- ics the need for gene function elucidation has led to the development of chromatographic tools that can now detect hundreds of me- tabolites in one chromatographic run. In addition, multivariate analysis has enabled classification of spoilage groups involving complex interactions. Postharvest losses of crops, due to spoilage, mainly by microbial contamination, are often very high. Even though metabo- lites have been used in the identification of food spoilage for a long time, the latest developments in the area of metabolomics are very encouraging for better achieving such a goal. In this paper, the gradual advances made in the use of metabolomics to diagnose spoilage of crops after harvest have been reviewed with comments on directions for future research. Main findings: The metabolomics approach has enabled not only separation of different degrees of food spoilage, but also identifica- tion of specific causes of food spoilage. The review reports: 1) what is involved in metabolomics studies; 2) a detailed description of several metabolites or combinations of few metabolites specific to spoilage of different fruits and vegetables; 3) multivariate models to discriminate classes of specific spoilage; 4) the possible application of such a technology to detect and diagnose diseases of postharvest fruits and vegetables under commercial conditions. Directions for future research: Metabolomics is a powerful biochemical tool. However, its full potential has not been exploited to diagnose spoilage of crops after harvest. It can be applied to analyse headspace gases, as well as to characterise the chemical composi- tion of living organisms, which in turn can be used in the diagnosis of food deterioration. The latest advances in the metabolomics tech- nology include sophisticated algorithms and software to automatically deconvolute chromatographic peaks and identify compounds using several databases. Understanding the details of metabolomics analysis is crucial for the efficient use of such a powerful tool to manage crop spoilage after harvest. The directions for the future research needed for the transfer of the metabolomics technology to reduce crop spoilage after harvest, under commercial conditions, are proposed. Keywords: Metabolic profiling; food spoilage; disease detection; postharvest pathology; volatile organic compounds; disease monitoring Abbreviations *Correspondence to: Dr. AC Kushalappa, Plant Science Department, McGill University, Ste. Anne de Bellevue, QC, Canada H9X 3V9. Fax : 514-398-7897 ; email : ajjamada.kushalappa@mcgill.ca Stewart Postharvest Review 2008, 2:12 Published online 01 April 2008 doi: 10.2212/spr.2008.2.12 Introduction The mechanisation of agricultural production, from sowing to processing, has led to the centralisation of fruit and vege- table production systems. Either the produce is grown on large farms and stored locally or it is transported to central- ised storage facilities. Thus, it is generally handled several times before it reaches the consumer. Crop losses occur not only during production but also after harvest. A large por- tion of the harvested produce is lost on its journey to the consumer. Losses occur in all operations from harvesting through handling, storage, processing and marketing. Thus, the shelf-life and food quality of a product depend not only on the genetic constitution of the commodity, but also on GC Gas Chromatography MS Mass Spectrometry PC Principal Component