Approximate non-destructive quantification of
porphyrins in butter by front face fluorescence
spectroscopy

Wold, Jens Petter; Lundby, Frank

doi:10.22358/jafs/74191/2007

Cited by 6 publications

(7 citation statements)

References 3 publications

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“…Front-face fluorescence spectroscopy is a nondestructive, rapid, and sensitive method, which can be used to detect and monitor photosensitizers in dairy products. Very low concentrations (probably below 1−1.5 ng/g) of different tetrapyrroles can be detected. , When photosensitizers are involved in photoreactions, either as part of type I reactions or when reacting with 1 O 2 after type II reactions, the molecules are degraded. The degraded molecular bonds correspond to the fluorescent ones.…”

Section: Resultsmentioning

confidence: 99%

“…Very low concentrations (probably below 1-1.5 ng/g) of different tetrapyrroles can be detected. 10,34 When photosensitizers are involved in photoreactions, either as part of type I reactions or when reacting with 1 O 2 after type II reactions, the molecules are degraded. The degraded molecular bonds correspond to the fluorescent ones.…”

Section: ' Materials and Methodsmentioning

confidence: 99%

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Effect of Naturally Occurring Tetrapyrroles on Photooxidation in Cow's Milk

Airado‐Rodríguez

Intawiwat

Skaret

et al. 2011

J. Agric. Food Chem.

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The objective of this work was to better understand the photosensitizing effect of riboflavin versus naturally occurring tetrapyrroles in cow's milk. This was done by exposure of milk samples to blue light (400-500 nm), which is absorbed by riboflavin and tetrapyrroles, orange light (575-750 nm), which is absorbed by tetrapyrroles but not riboflavin, and white light, which contains the entire visible region. The milk was exposed to about 1.6 W/m(2) in 20 h, and two different light sources were tested: HMI lamp and fluorescent light tubes used for commercial display. Sensory analysis showed that wavelengths longer than 575 nm induced significantly more off-flavors than wavelengths shorter than 500 nm. By fluorescence spectroscopy it was observed that tetrapyrroles, in particular, chlorophyllic compounds, were degraded more by orange light than by blue and that the degree of degradation correlated closely with the formation of sensory off-flavors. The fluorescent agent Singlet Oxygen Sensor Green (SOSG) was used to monitor the formation of singlet oxygen under the different light exposure conditions, and the method verified that singlet oxygen was formed in large proportions in milk exposed to wavelengths longer than 575 nm, presumably with minor or no involvement of riboflavin. The results suggest that cholorophyllic compounds are responsible for a major part of photooxidation in milk. It is also suggested that β-carotene protects against photooxidation under blue light because it absorbs a major portion of the light below 500 nm and thereby reduces reactions with photosensitizers.

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Section: Resultsmentioning

confidence: 99%

Section: ' Materials and Methodsmentioning

confidence: 99%

Effect of Naturally Occurring Tetrapyrroles on Photooxidation in Cow's Milk

Airado‐Rodríguez

Intawiwat

Skaret

et al. 2011

J. Agric. Food Chem.

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“…In addition, there are at least four more photoactive compounds, most likely chlorophyll derivatives (Wold et al, 2006). The concentrations of some of these compounds have been tentatively determined in butter by front face fluorescence spectroscopy (Wold & Lundby, 2007) and are very low (0.02ppm for PpIX). The compounds are fat soluble and when the concentrations for fat in butter are used for milk with 3.5% fat, the concentrations are in the range 0.8 ppb, about 250 times less than the concentration of riboflavin.…”

Section: Introductionmentioning

confidence: 99%

Assessment of the action spectrum for photooxidation in full fat bovine milk

2015

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The action spectrum for photooxidation in full fat bovine milk was measured. Samples of milk with air or argon in headspace were exposed to narrow wavelength bands of light in the range 400-700 nm. Photooxidation in terms of off-flavors was measured by a sensory panel, volatile compounds by headspace solid phase micro extraction (SPME-GC-MS), and photobleaching of photosensitizers in milk (riboflavin, protoporphyrin IX and a chlorophyllic compound) by front face fluorescence spectroscopy. The action spectrum deviated significantly from the absorption spectrum of milk. Significant oxidation was induced by wavelengths around 400 nm and 500-650 nm in milk with air in headspace. Argon in headspace gave significant oxidation also at 700 nm. It is suggested that protoporphyrin IX and chlorophyll are responsible for oxidation induced by wavelengths >500 nm, and that also riboflavin is contributing from 400 to 500 nm.

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“…Riboflavin, porphyrins and chlorophyll derivatives are naturally present as photo-sensitizers in dairy products such as cheese (Wold et al, 2005(Wold et al, , 2006a, butter (Wold & Lundby, 2007) and milk (Intawiwat et al, 2010). These photo-sensitizers can initiate photooxidation when exposed to visible light.…”

Section: Introductionmentioning

confidence: 99%