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Light-induced off-flavor development in cloudy apple juice
Midori Hashizume1, Michael H Gordon, Donald S Mottram
1Department of Food Biosciences, University of Reading, Whiteknights, Reading RG6 6AP, United Kingdom.
Journal of Agricultural and Food Chemistry
|October 4, 2007
Summary
Light exposure causes metallic off-flavors in cloudy apple juice due to photooxidation. Removing suspended solids significantly reduces the development of these undesirable volatile compounds during storage.
Area of Science:
- Food Science
- Analytical Chemistry
- Sensory Science
Background:
- Cloudy apple juice is susceptible to developing off-flavors during storage when exposed to light.
- Photooxidation is a known pathway for flavor degradation in food products.
Purpose of the Study:
- To investigate the development of off-flavors and volatile compounds in cloudy apple juice under light exposure.
- To identify the key volatile compounds contributing to light-induced off-flavors.
- To assess the role of suspended solids in this process.
Main Methods:
- Reconstituted cloudy apple juice from 'Golden Delicious' and 'Fuji' concentrates was stored under fluorescent light.
- Gas chromatography-olfactometry (GC-O) was used to identify volatile compounds.
- Centrifugation was employed to remove suspended solids.
Main Results:
- A metallic off-flavor was detected, primarily attributed to 1-octen-3-one.
- Six volatile compounds (pentanal, 2-methyl-1-penten-3-one, hexanal, (E)-2-heptenal, 6-methyl-5-hepten-2-one, and (E)-2-octenal) increased significantly after light exposure.
- 'Golden Delicious' apple juice exhibited higher volatile levels than 'Fuji' juice, correlating with higher suspended solids.
- Centrifugation significantly reduced volatile development upon light exposure.
Conclusions:
- Light exposure induces photooxidation in cloudy apple juice, leading to metallic off-flavors and the formation of specific volatile compounds.
- 1-octen-3-one is a major contributor to the metallic off-flavor.
- Suspended solids play a critical role in the light-induced development of volatiles, and their removal mitigates this issue.
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