Browsing by Author "Mallikarjunan, Kumar"
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- Comparison of kinetic models to describe high pressure and gamma irradiation used to inactivate Vibrio vulnificus and Vibrio parahaemolyticus prepared in buffer solution and whole oystersHu, X.; Mallikarjunan, Kumar; Koo, J.; Jahncke, M. L. (2005-03-01)
- Discriminating the Effects of Vineyard Management Practices on Grape and Wine Volatiles from Cabernet Franc and Merlot Grape Varieties Using Electronic Nose SystemsDevarajan, Yamuna Swetha (Virginia Tech, 2009-09-07)Vineyard management practices are known to affect fruit composition and resultant wines, in part, by altering fruit volatiles. Methods currently used to evaluate the impact of vineyard practices on grape/wine composition include measuring physico-chemistry indices and performing wine sensory analyses. These activities are both time-consuming and destructive. Two electronic nose (ENose) systems: a hand-held conducting polymer-based and a portable surface acoustic wave-based systems were investigated as grape monitoring tools. Vineyard treatments included the effect of canopy side (East vs. West and North vs. South), cluster thinning (unthinned, 1 cluster/shoot, and 1 & 2 cluster/shoot) and ethanol spray (5% v/v) on Cabernet franc, Merlot and both varieties respectively. ENose data were obtained in the field (over two growing seasons for canopy side and in 2008 for cluster thinning and ethanol spray) and laboratory (2007 for canopy side), across different sampling dates and compared with nine-grape/eight-wine chemistry assays, GC/MS (cluster thinning) and wine aroma sensory evaluations (triangular difference testing). ENose results demonstrated 100% significant differences between all Cabernet franc and Merlot treatments. Grape/wine chemistry indices, for both Cabernet franc and Merlot, did not differ among treatments (except ethanol treatment) across sampling dates or growing seasons and vineyard management practices. Wine aroma sensory evaluations demonstrated only limited differences (3 out of 8 comparisons: East vs. West, 1 cluster/shoot vs. 1 & 2 clusters/shoot and 1 cluster/shoot and 1 & 2 clusters/shoot). The high level of discrimination by ENose systems may provide opportunities to enhance the understanding of vineyard management activities.
- Discriminating the Effects of Vineyard Management Practices on Grape and Wine Volatiles from Cabernet Franc and Merlot Grape Varieties Using Electronic Nose SystemsDevarajan, Yamuna Swetha (Virginia Tech, 2009-08-07)Vineyard management practices are known to affect fruit composition and resultant wines, in part, by altering fruit volatiles. Methods currently used to evaluate the impact of vineyard practices on grape/wine composition include measuring physico-chemistry indices and performing wine sensory analyses. These activities are both time-consuming and destructive. Two electronic nose (ENose) systems: a hand-held conducting polymer-based and a portable surface acoustic wave-based systems were investigated as grape monitoring tools. Vineyard treatments included the effect of canopy side (East vs. West and North vs. South), cluster thinning (unthinned, 1 cluster/shoot, and 1 & 2 cluster/shoot) and ethanol spray (5% v/v) on Cabernet franc, Merlot and both varieties respectively. ENose data were obtained in the field (over two growing seasons for canopy side and in 2008 for cluster thinning and ethanol spray) and laboratory (2007 for canopy side), across different sampling dates and compared with nine-grape/eight-wine chemistry assays, GC/MS (cluster thinning) and wine aroma sensory evaluations (triangular difference testing). ENose results demonstrated 100% significant differences between all Cabernet franc and Merlot treatments. Grape/wine chemistry indices, for both Cabernet franc and Merlot, did not differ among treatments (except ethanol treatment) across sampling dates or growing seasons and vineyard management practices. Wine aroma sensory evaluations demonstrated only limited differences (3 out of 8 comparisons: East vs. West, 1 cluster/shoot vs. 1 & 2 clusters/shoot and 1 cluster/shoot and 1 & 2 clusters/shoot). The high level of discrimination by ENose systems may provide opportunities to enhance the understanding of vineyard management activities.
- Electronic Nose Analysis of Cabernet Sauvignon (Vitis vinifera L.) Grape and Wine Volatile Differences during Cold Soak and PostfermentationGardner, D. M.; Zoecklein, Bruce W.; Mallikarjunan, Kumar (American Society for Enology and Viticulture, 2011-03-01)Cold soak is a prefermentation maceration process at cold temperatures, traditionally used to enhance red wine color. This study monitored changes in Vitis vinifera L. cv. Cabernet Sauvignon volatiles using a commercial conducting polymer electronic nose (ENose) during a five-day cold soak and postfermentation. Principal component analysis (PCA) of juice volatiles detected by the ENose during cold soak showed PCI accounted for 95.7% of the variation. Various volatile associations were made with specific ENose sensors. In comparison, PCA of must chemistries had 52.4% of the variation accounted for by PCI. The PCA of wine volatiles detected by GC-MS showed PCI accounted for 97.1% of the variation between control and cold soak treatment, where control wine volatiles were associated with several ethyl esters, while cold soak wine volatiles were associated with diethyl succinate, isovaleric acid, benzyl alcohol, 3-methyl butanol, cis-3-hexenol, gamma-nonalactone, benzaldehyde, 2-methyl propanol, phenethyl acetate, 1-octanol, beta-damascenone, terpinene-4-ol, gamma-butyrolactone, ethyl acetate, hexanoic acid, citronellol, phenethyl alcohol, and n-butanol. Comparatively, PCI accounted for 100% of the total variance when using the ENose to measure volatile composition. Sensory evaluation did not demonstrate significant differences in aroma between control and cold soak wines. This study demonstrates differences in volatile chemistry between control and cold soak wines, as well as the ability to use a conducting polymer ENose as a simple tool for analysis of volatiles.
- Electronic Nose Evaluation of the Effects of Canopy Side on Cabernet franc (Vitis vinifera L.) Grape and Wine VolatilesDevarajan, Y. S.; Zoecklein, Bruce W.; Mallikarjunan, Kumar; Gardner, D. M. (American Society for Enology and Viticulture, 2011-03-01)The effect of grapevine canopy side (north versus south and east versus west) on grape and wine volatiles of Cabernet franc was evaluated during two growing seasons using two electronic nose systems based on conducting polymers and surface acoustic waves. Data from three sampling dates per season from both electronic noses were compared with physicochemistry and wine aroma sensory evaluations. Univariate and multivariate statistical analyses generally indicated grape physicochemistry indices could not differentiate consistently (p > 0.05) between canopy sides across growing seasons and sampling dates. Both electronic nose (ENose) systems provided complete discrimination of canopy sides for grapes and wine using canonical discriminant analysis. On average, the surface acoustic wave-based ENose explained <50% of variation for grapes and <60% for wine using the first principal component, compared to >80% for the conducting polymer-based ENose. Wine aroma sensory evaluation differentiated canopy sides in three of four evaluations.
- Inactivation of Salmonella enterica and Surrogate Enterococcus faecium on Whole Black Peppercorns and Cumin Seeds Using Vacuum Steam PasteurizationNewkirk, Jordan J.; Wu, Jian; Acuff, Jennifer C.; Caver, Chris B.; Mallikarjunan, Kumar; Wiersema, Brian D.; Williams, Robert C.; Ponder, Monica A. (Frontiers, 2018-08-07)Spices, including black pepper and cumin seeds, have been implicated in outbreaks of salmonellosis and prompted recalls of ready-to-eat products containing contaminated spices. Vacuum-assisted steam pasteurization is performed to improve the safety and quality of many low water activity products, however process parameters associated with inactivation on whole spices are not well described. The objective of this study was to determine the effectiveness of a lab-scale vacuum-assisted steam process for the inactivation of Salmonella enterica and its potential surrogate Enterococcus faecium ATCC 8459 inoculated onto the surface of whole peppercorns and cumin seeds. In addition, the effect of two inoculation preparation methods [growth on tryptic soy agar (TSA) or inclusion within a native microbiota biofilm], on the reduction of S. enterica serovars or E. faecium was compared on steam pasteurized whole black peppercorns. Spices were processed using steam under a vacuum to achieve a mean product temperature of 86.7 ± 2.8◦C for different dwell times. Salmonella inoculated using the TSA-grown method, required 83 and 70 s respectively to achieve a 5-log reduction of Salmonella on peppercorns and cumin seeds. Longer time periods were needed to achieve a 5-log reduction of Salmonella when it was present in a native biofilm on whole peppercorns. Survivor estimations were best predicted by the Weibull models. The mean log reductions of E. faecium were 0.9 log CFU/g lower than Salmonella on whole black peppercorns inoculated using the TSA-grown cells (P = 0.0021). The mean log reductions of Salmonella and E. faecium prepared using the biofilm-inclusion method were not significantly different (P = 0.76). E. faecium log CFU/g reductions were not significantly different compared to Salmonella on whole cumin seeds (P = 0.42) indicating that while reductions are comparable the surrogate may not always provide a conservative indication of complete Salmonella elimination for all spices processed using vacuum-assisted steam.
- Inactivation of Vibrio parahaemolyticus and Vibrio vulnificus in Phosphate-Buffered Saline and in Inoculated Whole Oysters by High-Pressure ProcessingKoo, J.; Jahncke, M. L.; Reno, P.; Mallikarjunan, Kumar (2006-04-01)
- Low Dose Gamma Irradiation to Reduce Pathogenic Vibrios in Live OystersAndrews, L.; Jahncke, M.; Mallikarjunan, Kumar (2003)
- Monitoring Effects of Ethanol Spray on Cabernet franc and Merlot Grapes and Wine Volatiles Using Electronic Nose SystemsZoecklein, Bruce W.; Devarajan, Y. S.; Mallikarjunan, Kumar; Gardner, D. M. (American Society for Enology and Viticulture, 2011-09-01)The ability of two electronic nose systems (conducting polymer and surface acoustic wave-based) to differentiate volatiles of grapes and wines treated with an aqueous ethanol spray (5% v/v) at veraison was evaluated. Ethanol spray induced fruit ethylene production immediately posttreatment, which then declined progressively. The electronic nose evaluations of grape volatiles were compared with Cabernet franc and Merlot physicochemistry and with wine gas chromatographic and aroma sensory data. Canonical discriminant and principal component analysis found that both electronic nose systems and the physicochemical measures (Brix, TA, pH, color intensity and hue, total phenols, glycosides, and berry weight) were able to discriminate between ethanol-treated and untreated grapes and wines for both cultivars. Grape physicochemical treatment differences were due mainly to variations in hue, phenolic-free glycosides, and total phenols. Aroma sensory evaluations using a consumer panel differentiated between ethanol treatments and controls for Merlot, but not for Cabernet franc wines.
- The "threads" of biosystems engineeringBriassoulis, D.; Gallego, E.; Pantaleo, A. M.; Holden, Nicholas M.; Owende, P.; Ting, K. C.; Mallikarjunan, Kumar (American Society of Agricultural and Biological Engineers, 2014)The core concepts, or threads, of biosystems engineering (BSEN) are variously understood by those within the discipline but have never been unequivocally defined due to BSEN's early stage of development. This makes communication and teaching difficult compared to other well-established engineering disciplines. Biosystems engineering is afield of engineering that integrates engineering science and design with applied biological, environmental, and agricultural sciences. It represents an evolution of the agricultural engineering discipline applied to all living organisms but generally does not include biomedical applications. The key element for the emerging EU biosystems engineering program of studies is to ensure that it offers essential minimum fundamental engineering knowledge and competences. A core curriculum developed by successive Erasmus thematic networks has benchmarked agricultural and biosystems engineering studies in Europe. The common basis of a core curriculum for the discipline across European countries and the U.S. has been defined by an EU-US Atlantis project, but this needs to be taken further by defining the threads that link courses together This article presents a structured approach to define the threads of BSEN. Definition of the mid-level competences and the associated learning outcomes has been one of the objectives of the EU-US Atlantis project TABE.NET. The mid-level competences and learning outcomes for each of six specializations within BSEN are defined, while the domain-specific knowledge to be acquired for each outcome is proposed. Once the proposed definitions are discussed, modified, and ultimately adopted, these threads will be available for the global development of BSEN.