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 Tetrapak-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.

Fusarium oxysporum f.sp. pisi (Fop) exists in pea production regions worldwide and causes a vascular wilt resulting in significant crop losses. Four races of Fop have been identified, and resistance to each was reportedly conferred by an individual single dominant gene. Fnw confers resistance to Fop race 2, which can be a serious pathogen for both green and dry pea production in the Pacific Northwest region of the United States. The objectives of this research were to (i) place Fnw on the Pisum genetic map, (ii) detect additional genetic factors associated with resistance to race 2 and (iii) identify closely linked markers for use in pea breeding A recombinant inbred line (RIL) population of 187 F 7 -derived lines from the cross ÔShawneeÕ/ÔBohatyrÕ was developed by single-seed decent. All 187 RILs, the parents and one set of race 2 pea differential entries were inoculated with Fop race 2 under controlled conditions in three experiments, each with two or three replications per entry. Disease reactions were recorded as percentage diseased plants 10-14 days postinoculation or at regular intervals through flowering or early pod fill. Data for progressive wilting over time, typical of Fop race 2, were used to calculate area under disease progress curve (AUDPC) values. Data for percentage diseased plants placed the putative single gene Fnw on Pisum sativum linkage group IV, with LOD scores ranging from 40.0 to 65.6 and minor loci on LG III (LOD 3.97 and 4.60). AUDPC values allowed for the detection of additional QTL on linkage group III with LOD scores of 3.97 and 4.60. The presence of recombinants in the population indicated that complementary genes were contributed by each parent, both of which showed intermediate reaction to Fop race 2. Results of this research provide a basis for marker-assisted selection of the major Fnw loci in both green and dry pea breeding programmes, but additional research is necessary to fully characterize the complementary gene action governing resistance of the two minor loci identified.

Both Harmonia axyridis and Coccinella septempunctata can contribute alkyl methoxypyrazines, and particularly isopropyl methoxypyrazine, to wine at concentrations that can have a negative impact on wine quality. These findings will allow grape growers and winemakers to be more aware of the risks posed by 7 Spot beetles, and to take the appropriate preventative and remedial actions. Furthermore, this is the first time dimethyl methoxypyrazine is reported in wine, either as an endogenous or Coccinellidae-derived odorant.

Background: β-glucosidase is an enzyme important to flavour enhancement. It hydrolyzes glucosides to release aglycones-aroma precursors that are bound to a sugar molecule-thereby making them available to contribute to the flavour of foods and beverages. While there is strong interest within the food and beverage industry to optimizing flavour through the use of exogenous and endogenous glucosidase in production, little is known regarding the possible occurrence of these enzymes within the human oral cavity. This could be an important source of flavour release and/or account for some differences between individuals in flavour perception. In the present study, we determined whether β-glucosidase is present in human saliva. First, an existing spectrophotometric assay that uses p-nitrophenyl-β-O-D-glucopyranoside as a substrate was modified and optimized for use in human saliva. The following variables were evaluated and where necessary, optimized: linearity of the assay signal, possible matrix interference, the effect of heat inactivation of the saliva, absorbance wavelength maxima, substrate saturation concentration, maximum saliva volume and the inclusion of α-cyclodextrin. The modified assay was then used to screen for β-glucosidase activity in the saliva of 20 individuals. Of the 20 samples analyzed, four were tentatively identified as containing active β-glucosidase and were further investigated. Results: Significant differences (p < 0.05) in absorbance values (A400 nm ) between these saliva samples confirm low levels of β-glucosidase activity in approximately 20% of the population sampled. Conclusions: Inter-individual variability exists in β-glucosidase activity within the oral cavity. The described method can be applied to rapidly assay a large population of individuals, and further elucidate the extent and significance of salivary β-glucosidase activity within the context of human flavour perception and enhancement.

Abstract:The purpose of this study was to investigate the effect of wine style and cane sugar addition in the liqueur d'expedition (dosage) solution on volatile aroma compounds (VOCs) in traditional method sparkling wine. There were 24 bottles of each treatment produced. Treatments were sparkling wine zero dosage (ZD); NV sparkling wine + sugar (BS); unoaked still Chardonnay wine + sugar (UC); Pinot noir 2009 sparkling wine + sugar (PN); Niagara produced Brandy + sugar (B) and Icewine (IW). The control treatment in the sensory analysis was an oaked still Chardonnay wine + sugar (OC) because the zero-dosage wine was not suitable for a difference test that compared wines with sugar to one without. Standard wine chemical parameters were analysed before disgorging and after liqueur d'expedition was added and included; pH, titratable acidity (TA g/L), alcohol (v/v %), residual sugar (RS g/L), free and total SO 2 and total phenolics (A.U.). Volatile aroma compounds (VOCs) analysed by Headspace Solid-Phase Micro-Extraction Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) included two alcohols, and six ethyl esters. ZD wines had the highest foam height and highest dissolved oxygen level. Sugar affected VOC concentrations in all treatments at five weeks post-disgorging, but by 15 weeks after liqueur d'expedition addition, the wine with added sugar had similar VOC concentrations to the ZD wines. The type of wines used in the dosage solutions had more influence on VOC concentrations than sugar addition.