Thesis
The impact of multicoloured Asian Lady Beetles on the sensory properties of Concord and Niagara grape juice
Washington State University
Master of Science (MS), Washington State University
2008
Handle:
https://hdl.handle.net/2376/101065
Abstract
The presence of Multicoloured Asian Lady Beetles (MALB) in juice and wine can cause objectionable aromas and flavours. The overall hypothesis of this study was that the presence of MALB can significantly affect the aroma, taste/flavour and mouthfeel properties of Concord and Niagara grape juice. The first objective was to determine if MALB changed the analytical values of the juice. For Concord juice, significant decreases were observed with pH, Brix and titratable acidity. For Niagara juice, pH significantly decreased and titratable acidity significantly increased with increased MALB taint. The second objective was to determine the best estimate threshold (BET) of MALB in both juices. Panelists (n= 48) determined the BET for Concord grape juice was 1.98 MALB/L and 0.65 MALB/L for Niagara grape juice. Following storage of Concord grape juice for 11 mo, panelists (n=17) determined the BET was 1.66 MALB/L. The third objective of this study was to determine which sensory characteristics of the grape juices were significantly impacted by the presence of MALB. Ten trained panelists (n=10) found significant differences in Concord grape juice in vegetal aroma and earthy flavour as MALB increased from 0.45 MALB/L to 7.2 MALB/L. For Niagara grape juice, the trained panel (n= 8) found significant differences in honey, vegetal and earthy aromas and flavours, grape flavour, sweetness, sourness and astringency. The fourth objective of the study was to determine which juice, MALB or control was preferred by consumers (n=60). For Concord grape juice, consumers significantly rejected the aroma of MALB juice at 1.8 and 3.6 MALB/L. For taste/flavour, significant rejection of MALB juice occurred at 3.6 MALB/L. For Niagara juice, consumers significantly rejected the aroma of the juice at 3.6 MALB/L. This study demonstrated the presence of MALB can negatively impact the sensory properties of Concord and Niagara grape juice. More research is needed to determine the remediation of grape juice should MALB taint occur. Grape juice processors can use this research for quality control measures and for setting tolerance limits.
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Details
- Title
- The impact of multicoloured Asian Lady Beetles on the sensory properties of Concord and Niagara grape juice
- Creators
- Luan N. Weekes
- Contributors
- Carolyn Felicity Ross (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525086201842
- Language
- English
- Resource Type
- Thesis