A food fluorescence library by Jakob Christensen, 2005
Background
The present site contains a food fluorescence library (FOODFLUOR) in the form of steady-state fluorescence landscapes from a variety of intact food samples, plus a list of some food relevant fluorophores in pure solutions. The listed fluorescence measurements are intended to serve as a work of reference, a library, which can hopefully inspire and help scientists that are interested in or want to start exploring the intrinsic fluorescence of food and food systems.
Fluorescence database
Fluorescence landscapes of eleven fluorophores and a broad variety of intact food samples is included in this database. Measurements of the fluorophores were performed on two different instruments, yielding three separate lists:
Fluorophores measured on Perkin Elmer LS50 B spectrofluorometer
Fluorophores measured on Varian Cary Eclipse spectrofluorometer
Intact food samples measured on Perkin Elmer LS50 B spectrofluorometer
The fluorescence properties of the selected samples can be viewed at this site or the data from the experiments can be downloaded in MS-Excel format. Please note that the presented fluorescence landscapes are not corrected.
Reference
If you want to use the data or refer to the results, please refer to:
Food Fluorescence Library, Quality & Technology, Department of Food Science, Faculty of Science, University of Copenhagen, Denmark, www.models.life.ku.dk
Pure solutions of fluorophores are measured. Appropriate concentration levels were chosen for each fluorophore in order to avoid concentration quenching. Fluorescence landscapes were measured on PerkinElmer LS50B spectrofluorometer in a cuvette with the traditional right-angle sampling geometry. Water was used as solvent, iso-octan when the fluorophore is not soluble in water. The landscapes were measured in different spectral ranges, using an obey-file in the FLDM instrument controlling software. Common measurement parameters:
Slit width: 5 nm for both excitation and emission light
Step size: 2 nm for excitation
Step size: 1 nm for emission
Fluorescence emission was only recorded between the 1st and 2nd order Rayleigh scatter. No emission above 700 nm was recorded.
If any minor Rayleigh scatter appeared in the recorded fluorescence data, it was removed in the preliminary signal processing, before further data analysis.
Overview two: Excitation and emission profiles of all fluorophores
Overview three: Comparison between Perkin Elmer LS50B and Varian Cary Eclipse spectrofluorometer.
Download the data as MS-Excel file (each sheet is one fluorophore, 5.3MB); also available in Matlab format
List of measured compounds | |||||||
Fluorophore | Conc. (M) | EX λmax (nm) | EM λmax (nm) | Imax * |
Measuring range (EX, nm) |
Solvent | |
Phenyl alanine | 10-3 M | 258 | 284 | 32 | 250-320 | Water | |
Tyrosine | 10-5 M |
276 |
302 | 28 | 250-320 | Water | |
Tryptophan | 10-5 M | 280 | 357 | 100 | 250-320 | Water | |
Vitamin A (Retinol) |
10-5 M | 346 | 480 | 16 | 250-380 | Iso-octane | |
Vitamin B2 (Riboflavin) |
10-5 M |
270 (382,448) |
518 | 167 | 250-510 | Water | |
Vitamin B6 (Pyridoxin) |
10-5 M | 328 | 393 | 51 | 250-360 | Water | |
Vitamin E (α-Tocopherol) |
10-4 M | 298 | 326 | 167 | 250-320 | Iso-octane | |
NADH | 10-4 M | 344 | 465 | 16 | 260-470 | Water | |
ATP | 10-3 M | 292 | 388 | 33 | 260-320 | Water | |
Chlorophyll A | 10-6 M | 428 | 663 | 56 | 340-650 | Iso-octane | |
Hematoporphyrin | 10-5 M | 396 | 614 | 27 | 300-550 | Iso-octane | |
*normalized according to tryptophan (= 100) |
Pure solutions of fluorophores are measured. Appropriate concentration levels were chosen for each fluorophore in order to avoid concentration quenching. Fluorescence landscapes were measured on Cary Varian Eclipse spectrofluorometer in a cuvette with the traditional right-angle sampling geometry. Water was used as solvent, iso-octan when the fluorophore is not soluble in water. The landscapes were measured in different spectral ranges, using a measuring routine programmed in ADL in the instrument controlling software. Common measurement parameters:
Rayleigh scatter appearing in the recorded fluorescence data was removed in the preliminary signal processing, before further data analysis.
Overview two: Excitation and emission profiles of all fluorophores
Overview three: Comparison between Perkin Elmer LS50B and Varian Cary Eclipse spectrofluorometer.
Download the data as MS-Excel file (each sheet is one fluorophore, 4.6MB); also available in Matlab format
List of measured compounds | |||||||
Fluorophore | Conc. (M) | EX λmax (nm) | EM λmax (nm) | Imax * |
Measuring range (EX, nm) |
Solvent | |
Phenyl alanine | 10-3 M | 262 | 281 | 38 | 230-310/ 230-450 | Water | |
Tyrosine | 10-5 M | 278 | 302 | 96 | 230-310/ 230-450 | Water | |
Tryptophan | 10-5 M | (230) 276 | 355 | 100 | 230-310/ 230-450 | Water | |
Vitamin A (Retinol) |
10-5 M | 328 | 484 | 8 | 260-380/ 400-620 | Iso-octane | |
Vitamin B2 (Riboflavin) |
10-5 M |
268 (372+444) |
528 | 58 | 250-500/ 480-590 | Water | |
Vitamin B6 (Pyridoxin) |
10-5 M | 326 | 396 | 18 | 220-360/ 350-470 | Water | |
Vitamin E (α-Tocopherol) |
10-4 M | 298 | 323 | 70 | 220-320/ 290-380 | Iso-octane | |
NADH | 10-4 M | 338 | 465 | 16 | 260-460/ 380-590 | Water | |
ATP | 10-3 M | 292 | 392 | 20 | 260-320/ 320-500 | Water | |
Chlorophyll A | 10-6 M | 428 | 663 | 16 | 350-650/ 640-690 | Iso-octane | |
Hematoporphyrin | 10-5 M | 394 | 613 | 12 | 300-550/ 590-690 | Iso-octane | |
*normalized according to tryptophan (= 100) |
Fluorescence landscapes of a variety of intact food samples liquid as well as solid - were measured on Perkin Elmer LS50B spectrofluorometer using a front-face solid sample accessory with 60o sampling geometry. Liquid samples were measured in quartz cuvettes and solid samples in sample cups. The landscapes were recorded using an obey-file in the FLDM instrument controlling software with following measurement parameters:
Slit width, excitation: 5 nm
Slit width, emission: 10 nm
Step size: 5 nm for excitation
Step size: 1 nm for emission
Excitation range: 250-650 nm
All fluorescence emission was only recorded between the 1st and 2nd order Rayleigh scatter. No emission above 700 nm was recorded. An emission 1% attenuation filter was used for samples yielding too high fluorescence intensity. If any minor Rayleigh scatter appeared in the recorded fluorescence data, it was removed in the preliminary signal processing, before further data analysis.
Download the data as MS-Excel file (each sheet is one food sample, 8.3MB); also available in Matlab format
List of measured food samples | ||||||
Sample | pH | Filter | EX λmax (nm) | EM λmax (nm) | Imax | |
Milk (1.5 % fat) | 6.69 | √ | 285 | 340 | 6900* | |
Yoghurt, plain (3.5 %) | 3.98 | √ | 285 | 341 | 6200* | |
Rape seed oil | 360 | 444 | 812 | |||
Olive oil | 610 | 681 | 643 | |||
Orange juice | 3.62 | 510 | 530 | 53 | ||
Apple juice | 4.02 | 390 | 461 | 57 | ||
Soy sauce | 4.66 | 640 | 685 | 8 | ||
Beer, Carlsberg | 4.32 | 390 | 465 | 242 | ||
Beer, Elephant | 4.29 | 400 | 489 | 221 | ||
White wine | 3.21 | 385 | 456 | 199 | ||
Rice | 410 | 488 | 584 | |||
Wheat flour | 285 | 338 | 185 | |||
Cane sugar | 345 | 462 | 56 | |||
Oatmeal | 285 | 338 | 18 | |||
Emmenthaler | √ | 295 | 354 | 4500* | ||
Gorgonzola | √ | 290 | 346 | 4300* | ||
Butter | 325 | 407 | 923 | |||
Beef | 285 | 326 | 135 | |||
Pork | 296 | 334 | 888 | |||
Olive, green | 420 | 677 | 170 | |||
Marzipan | 460 | 517 | 488 | |||
Chocolate | 285 | 338 | 20 | |||
Carrot | 285 | 360 | 101 | |||
Potato | 290 | 377 | 218 | |||
Pear | 290 | 371 | 100 | |||
Tomato | 635 | 655 | 46 | |||
Apple | 510 | 530 | 60 | |||
*calculated value; recorded with 1% attenuation, so Ix100 is listed. |
All the Fluorescence landscapes (both fluorophores for both instruments and intact food samples in one big file) are available in Matlab, version 5/6 compatible.
Also available: the DOMFluor database (Dissolved Organic Matter)