malbjuicethresholds

malbjuicethresholds - JFS S: Sensory and Food Quality...

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S: Sensory & Food Quality JFS S: Sensory and Food Quality Impact of Multicolored Asian Lady Beetles on the Sensory Properties of Concord and Niagara Grape Juice L UAN N. W EEKES ,D OUGLAS W ALSH ,H OLLY F ERGUSON , AND C AROLYN F. R OSS ABSTRACT: The presence of Multicolored Asian Lady Beetles (MALB) in grape juice is increasingly problematic. The overall objective of this study was to determine the specific sensory impacts of MALB on Concord and Niagara grape juice. The aroma threshold for MALB-taint in both juices was determined and expressed as the best estimate thresh- old (BET). The aroma BET for MALB-taint in Concord grape juice was 1.8 and 0.65 MALB/L Niagara grape juice. The specific sensory attributes of the grape juices influenced by the presence of MALB were then described. In Concord grape juice, trained panelists ( n = 9) found significant increases in vegetal aroma and earthy flavor as MALB con- centration increased from 0.45 to 7.2 MALB/L. In Niagara grape juice, with increasing MALB concentration, trained panelists ( n = 8) indicated significant decreases in honey and sweetness with corresponding increases in sourness, astringency, and vegetal and earthy aromas and flavors ( P < 0.05). For both aroma and flavor, consumer rejection studies were performed using paired preference comparisons of control juice to MALB-tainted grape juice. For Con- cord grape juice, consumers ( n = 60) rejected the aroma of MALB-tainted juice at 1.8 MALB/L and the taste/flavor of the MALB-tainted juice at 3.6 MALB/L. For Niagara juice, consumers rejected the aroma of the juice at 3.6 MALB/L. This study demonstrated the presence of MALB negatively impacts the sensory properties of Concord and Niagara grape juice. Grape juice processors may use this research for quality control measures and for establishing tolerance limits. Practical Application: The Multicolored Asian Ladybeetle (MALB), initially used for biocontrol, has been shown in previous literature to impact the sensory properties of wines. The presence of MALB in grape juice is now becoming problematic; however, there is little research describing the specific sensory impacts of MALB on grape juice. This study examined the sensory impact of MALB on both Concord and Niagara grape juice. While the threshold and trained panel evaluations from this study provide valuable sensory profile information, grape juice processors may be particularly interested in the consumer rejection of MALB-tainted grape juice as they can use this research for quality control measures and for establishing tolerance limits. Keywords: Concord, grape juice, Multicolored Asian Lady Beetle, Niagara, taint Introduction T he United States is one of the world’s largest producers of grapes and the largest user of grape juice and grape juice concentrate (Bates and others 2001). An increasingly challeng- ing issue in grapes is the presence of the multicolored Asian Lady beetle (MALB). The MALB or Harmonia axyridis Pallas (Cleoptera:Coccinellidae) is a predator coccinellid, native to cen- tral and eastern Asia. MALB have been found in North America on
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This note was uploaded on 09/29/2010 for the course VEN 91863 taught by Professor Hildergardheymann during the Spring '09 term at UC Davis.

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malbjuicethresholds - JFS S: Sensory and Food Quality...

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