Muscadine grapes (Vitis rotundifolia Michx.), native to the southeastern United States, have a distinct flavor, and grocers are interested in marketing them as table grapes. Two studies using 'Fry' muscadines were conducted to assist the muscadine industry in providing quality table grapes. Study 1 (1998 and 1999) evaluated density sorting and relationships between maturity, color, soluble solids, firmness, shelf life, and sensory evaluation of grapes. Study 2 (1998) determined the effect of storage on quality attributes of different maturities of grapes and evaluated use of polyethylene bags to extend their storage. Density separation successfully sorted grapes by maturity. Muscadine berry color may allow for visual or electronic sorting to eliminate immature fruit. Sensory panelists could distinguish differences in maturities for all sensory attributes. In 1999 maturities 3 and 4 (≈24-33 soluble solids: acid ratio) were preferred overall by panelists. As maturity increased, soluble solids and pH increased, and acidity decreased. Firmness decreased as maturity and storage at 2 °C increased. Percent decay increased with maturity and storage time. Grapes stored in polyethylene bags had reduced decay. A chart developed from the 1999 data related berry color to soluble solids: acid ratio, soluble solids, tartaric acid, and pH. Data from these studies can be used by industry to establish harvest parameters and enhance marketability of 'Fry' muscadine grapes.
Red wine is composed of a complex matrix of compounds that can interfere with analysis. A high-performance liquid chromatography (HPLC) procedure was developed to efficiently analyze organic acids, sugars, glycerol, and ethanol in Cynthiana (Vitis aestivalis) wine. Standard laboratory procedures (pH, titratable acidity, and color attributes) and HPLC were found reproducible for Cynthiana wine. HPLC recovery efficiency was determined by analysis of spiked and unspiked samples (model, Cynthiana, and Syrah (Vitis vinifera) wines). Although recovery of components was greater in the model wine, recovery in Cynthiana and Syrah wine was comparable. The HPLC procedure was further compared to commercial rapid enzyme analysis tests using model, Cynthiana, and Syrah wines. HPLC analyses were more accurate than enzymatic tests for determining components in the model, Cynthiana, and Syrah wines. Considering the complexity of the wines analyzed, reproducibility and recovery of the HPLC procedure was demonstrated and showed improvement and precision when compared to existing methods.
Membrane and resin ion-exchange technology was used for pH reduction and production of Cynthiana (Vitis aestivalis) wine, which can have high pH and high titratable acidity. Wine attributes were monitored during storage for 6 months at 21 and 38 degrees C. Nonadjusted Cynthiana wine (pH 4.1) was compared to ion-exchange-adjusted wine (pH 3.5). Ion exchange lowered the pH and potassium content and increased the titratable acidity of wine without having detrimental effects on color and phenolics. No trends were found to indicate differences between manufacturers of membranes and resins on pH-adjusted Cynthiana wine. Wine treated with membrane ion exchange was higher in color density and phenolics than resin-treated wine. During storage at both temperatures, the quality of the wine decreased, with greater degradation at 38 degrees C. Ion exchange decreased the pH of Cynthiana wine without negatively affecting wine quality attributes. A panel familiar with characteristics of Cynthiana wine found that the color and flavor of the pH-adjusted wine was improved.
Muscadine grapes (Vitis rotundifolia michx.) are highly perishable, with a short harvest season. The objective of this study was to enhance the commercial viability of muscadine grapes by developing harvesting and handling systems through interstate shipment studies, using sulfur dioxide and/or polyethylene overwrap treatments. Cultivars Fry, Summit and Granny Val from Florida, Arkansas and Mississippi, respectively, were shipped from each region to the other in refrigerated trucks for subsequent storage at OC and evaluation at 0, 2, 4 and 6 weeks. Biochemical properties: pH, titratable acidity and degrees Brix, remained fairly constant with time for all cultivars, under all treatments. The cultivar, Granny Val, which was shipped, wrinkled after 2 weeks' storage, but maintained 6 weeks' shelf‐life in the in‐house study. ‘Summit’ shelf‐life was increased to 4 weeks with SO2 treatment at all test sites while ‘Fry’ became bleached by SO2. The shelf‐life of ‘Fry’ was 6 weeks in the in‐house study using
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