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Grape Quality (grape + quality)
Selected AbstractsImproving Grape Quality Using Microwave Vacuum Drying Associated with Temperature ControlJOURNAL OF FOOD SCIENCE, Issue 1 2007C. D. Clary ABSTRACT:, Microwave (MW) vacuum dehydration using temperature to control the level of MW power demonstrated potential in improving the performance of the process. Product surface temperature measured by an infrared temperature sensor was used to control MW power at any level between 0 and 3 kW. Multiple linear regression analysis indicated an r2= 0.942 for prediction of final moisture content and r2= 0.985 for prediction of puffed character of grapes based on product temperature, time, specific energy, fresh fruit sugar, and fresh fruit moisture content. Temperature was found to be the most significant predictor. The elemental and compound contents of grapes dried using MW vacuum was compared to sun-dried raisins. The grapes dried using MW vacuum exhibited better preservation. Vitamin A was found in the MW-vacuum-dried grapes but none was detected in the raisins, and Vitamin C, thiamine, and riboflavin were also higher in the MW-vacuum-dried grapes than in the raisins. [source] Effects of Mild Heat Treatment on Microbial Growth and Product Quality of Packaged Fresh-Cut Table GrapesJOURNAL OF FOOD SCIENCE, Issue 8 2007L. Kou ABSTRACT:, The changes in packaged fresh-cut grape quality and microbial growth as affected by mild heat treatments and the retention of grape cap stems during 5 °C storage were evaluated. Each individual grape was either manually pulled off (stemless) from the stems, or cut (cut stem) to allow for a 1- to 2-mm cap stem remaining on the berry. The samples were sanitized in 100 mg/L chlorine solution for 1 min, followed by a mild heat treatment in a water bath (45 °C, 8 min) or an oven (55 °C, 5 min). After cooling, the berries were packaged in rigid trays sealed with a gas permeable film and stored at 5 °C. Product quality and decay rate were evaluated periodically during storage. The results indicate that in the package headspace for hot water treatment of stemless grapes, partial pressures of O2 declined significantly (P < 0.05) less and C2H4 increased significantly (P < 0.001) less than for the control and hot air treatment. Stem removal and heat treatment had significant (P < 0.05) effects on the decay rate of grapes during storage. Hot water treatment maintained a significantly lower decay rate than the control and hot air treatment throughout the entire storage. Color and texture were not significantly (P > 0.05) affected by either heat treatment or stem removal. Grapes that retained the cap stems and received hot water treatment had the lowest decay rate and lowest microbial growth with the absence of any negative impact on grape color, texture, and flavor. [source] Identification and significance of sources of spatial variation in grapevine water statusAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2010J.A. TAYLOR Abstract Background and Aims:, Water stress in grapevines is directly linked to grape quality. Differential vine water management should therefore be strongly linked to the water stress in the vine. To do this, an understanding of the dominant drivers and indicators of vine water status are needed from a sub-block to whole vineyard level. This understanding will help generate effective vine water status models for variable rate irrigation systems. Methods and Results:, A vineyard in the south of France was sampled for pre-dawn leaf water potential (,PD) at several dates during the growing season for two consecutive years. Sampling was stratified by soil types and relative within-block vegetative expression. A recursive partitioning analysis identified that cultivar had a dominant effect at low water stress, while vegetative expression and then soil unit effects became dominant as water restriction increased. Variance in ,PD was calculated at difference scales (plant, site, block and vineyard) and Smith's heterogeneity law was used to evaluate the scalar nature of ,PD variance. Spatial heterogeneity increased as the season and water restriction increased. Conclusion:, Variance in ,PD changed temporally through a season and the dominant drivers/indicators also changed. The opportunity to spatially manage water stress (irrigation) increased as water restriction increased. Significance of the Study:, Managing vine water stress helps optimise production and a ,PD model would be a useful addition to a viticulture decision support system. This study identified how the variance in ,PD evolved during a season and the best ancillary indicators of ,PD for spatial and temporal modelling. [source] Abiotic stress and plant responses from the whole vine to the genesAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2010G.R. CRAMER Abstract Drought, salinity and extreme temperatures significantly limit the distribution of grapes around the world. In this review, the literature of grape responses to abiotic stress with particular reference to whole plant and molecular responses observed in recent studies is discussed. A number of short-term and long-term studies on grapevine shoots and berries have been conducted using a systems biology approach. Transcripts, proteins and metabolites were profiled. Water deficit, salinity and chilling altered the steady-state abundance of a large number of transcripts. Common responses to these stresses included changes in hormone metabolism, particularly abscisic acid (ABA), photosynthesis, growth, transcription, protein synthesis, signalling and cellular defences. Some of the transcriptional changes induced by stress were confirmed by proteomic and metabolomic analyses. More than 2000 genes were identified whose transcript abundance was altered by both water deficit and ABA. Different gene sets were used to map molecular pathways regulated by ABA, water deficit, salinity and chilling in grapevine. This work supports the hypothesis that ABA is a central regulator of abiotic stress tolerance mechanisms. ABA affects signalling pathways that trigger important molecular activities involving metabolism, transcription, protein synthesis, and cellular defence and also regulates important physiological responses such as stomatal conductance, photoprotection and growth. Systems biology approaches are providing more comprehensive understanding of the complex plant responses to abiotic stress. The molecular sets generated from mapping the ABA-inducible stress responses provide numerous targets for genetic and cultural manipulation for improved plant protection and grape quality. [source] | ||||||||||