| Popis: |
Norvegia cheese samples were packed in air and nitrogen atmospheres and exposed to light of different colours, blue (350–560 nm), green (450–620 nm) and red (580–700 nm). After 7 days of light exposure, each cheese was sliced, from the exposure surface and down, into eight slices of 3 mm thickness. The slices were analyzed by sensory analysis and fluorescence spectroscopy, enabling studies of how photo-oxidation progressed as a function of depth of the cheese. Green light gave the most oxidation at the surface for air stored samples. Oxidized flavours at depths down to 9 mm were more intense for exposure to red and green light. Blue light degraded riboflavin in the two upper layers (0–6 mm), whereas red and green light affected hematoporphyrin, protoporphyrin IX and chlorophyll as far as 21 mm into the cheese. The results suggest that tetrapyrroles are responsible for photo-oxidation at the surface and the interior of the cheese. |
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