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Effect of Oxygen Concentration on Photo‐oxidation and Photosensitizer Bleaching in Butter
Author(s) -
Wold Jens Petter,
Veberg Dahl Annette,
Lundby Frank,
Nilsen Asgeir Nikolai,
Juzeniene Asta,
Moan Johan
Publication year - 2009
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2008.00492.x
Subject(s) - photobleaching , chemistry , oxygen , photochemistry , photosensitizer , fluorescence , analytical chemistry (journal) , optics , environmental chemistry , organic chemistry , physics
The effect of headspace oxygen concentration and color of light on photo‐oxidation and degradation of photosensitizers in butter was studied. Butter samples were stored under 0%, 0.4%, 0.8%, 1.6%, 3.0%, 5.0%, 21% oxygen, and exposed to violet, green or red light. Storage time was 36 h. Degree of photo‐oxidation was measured by a trained sensory panel. Photobleaching of six different photosensitizers was estimated based on front face fluorescence excitation and emission landscapes and spectral curve resolution (parallel factor analysis). The higher oxygen concentration, the more sensory degraded were the samples. Violet light resulted in slightly higher degrees of photo‐oxidation than green and red light for low oxygen concentrations. Bleaching rate and course as function of O 2 concentration differed between the photosensitizers. It is suggested that the rate of photobleaching is a balance between type I and type II photoreactions.