pubs.acs.org/JAFC Published on Web 05/11/2009 © 2009 American Chemical Society 4680 J. Agric. Food Chem. 2009, 57, 4680–4690 DOI:10.1021/jf803720k Effect of Closure and Packaging Type on 3-Alkyl- 2-methoxypyrazines and Other Impact Odorants of Riesling and Cabernet Franc Wines AMY BLAKE, † YORGOS KOTSERIDIS, ^ IAN D. BRINDLE, 3 DEBBIE INGLIS, †,§ M. SEARS, X AND GARY J. PICKERING* ,†,§ † Department of Biological Sciences and § Cool Climate Oenology and Viticulture Institute and 3 Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada, ^ Department of Food Science and Technology, Agricultural University of Athens, Athens, Greece, and X Department of Environmental Biology, University of Guelph, Guelph, Ontario, Canada 3-Alkyl-2-methoxypyrazines (MPs) represent an important and potent class of grape- and insect- derived odor-active compounds associated with wine quality. Thirty nanograms per liter each of 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl- 2-methoxypyrazine (SBMP) was added to Riesling and Cabernet Franc wines and monitored with headspace solid-phase microextraction and gas chromatography-mass spectrometry over 18 months to investigate the effects of various closure and packaging options on MPs. Changes in MP concentrations during bottle aging varied with closure/packaging option, with the greatest decrease evident in Tetrapak cartons. After 18 months, IBMP, IPMP, and SBMP in both Tetra- pak-stored wines decreased by approximately 45, 32, and 26%, respectively. Similar changes were observed in other impact odorants to previous studies, including a greater decrease in odorant concentrations in wines closed with synthetic corks compared to natural corks and screw caps. These differences are thought to be due to the differential sorptive capacities of the various closure types. Overall, the data suggest that differences in gas permeability/contribution from the different closure and packaging options strongly associate with changes in wine composition during aging. KEYWORDS: 3-Alkyl-2-methoxypyrazine; methoxypyrazines; wine packaging; wine closures; Cabernet Franc; Riesling; sorption; greenness; ladybug taint; Harmonia axyridis INTRODUCTION 3-Isobutyl-2-methoxypyrazine (IBMP), 3-sec-butyl-2-methox- ypyrazine (SBMP), and 3-isopropyl-2-methoxypyrazine (IPMP) are three grape-derived volatile compounds that elicit green and vegetative perceptions in wine. Although these MPs can positively influence wine quality in some varieties (1 ), at higher concentra- tions they are dominant and unpleasant (2 ), can mask “fruity/ floral” aromas (3 ), and are associated with wines from cooler climates (4-6) and under-ripe, low-quality fruit (5, 6). Recently, lady beetles were identified as a second source of elevated MPs in wine that has been named “ladybug taint” (LBT) (7 ). LBT is a wine defect resulting from the undesired incorporation of lady beetles (Coleoptera: Coccinellidae), particularly Harmonia axyridis (commonly called the Multicolored Asian Lady Beetle, MALB), into the fermentation process responsible for millions of dollars of lost revenue from downgraded or discarded wine in southern Ontario and parts of the United States (8 ). The prevalence of H. axyridis in other wine regions, including Italy, France, Spain, South Africa, and Argentina (9 ), suggests that LBT could be or become a more widespread problem for the wine industry. Regardless of source, MPs can be identified and measured in wines in trace amounts, and due to their extremely low sensory detection thresholds;in the high picograms per liter to low nanograms per liter range (4, 10, 11);have the potential to significantly affect wine quality. Efforts to reduce MP levels have included both viticultural (12, 13) and enological (14 ) interven- tions. However, attempts to decrease MP concentrations in wine using conventional treatments, such as fining, have had limited success (15 ), and novel approaches are required. Closure and packaging options may offer one such approach. The capacity for packaging to directly remove volatile com- pounds through sorptive processes is termed flavor scalping and has been well established in the food science/technology literature and exploited commercially. It has been noted particularly with polymer packaging and nonpolar flavor compounds (16 ). In the investigation of the capacity of natural and agglomerate corks to contribute the taint compound 2,4,6-trichloroanisole to wine, it was observed that these closures had an even greater ability to absorb the compounds (17 ). Flavor scalping has since been characterized in wine from a comprehensive bottle-aging trial at the Australian Wine Research Institute, which investigated changes in composition in a Semillon wine after volatile com- pounds from a range of chemical classes were added and the bottles closed with natural, synthetic, and technical corks and *Author to whom correspondence should be addressed [telephone: (905) 688-5550, ext. 4715; fax: (905) 688-1855; e-mail: gary.pickering@ brocku.ca].