Flavor Precursors

FSN 605 - Laboratory



Date Performed: February 12, 2002

Report Due: February 19, 2002

Flavor production is an important attribute of non-enzymatic browning. The complexity of food flavor is often approached by following flavor precursors in simplified model systems. The purpose of this laboratory is to observe the types of flavors resulting from the interaction of various amino acids and sugars as flavor precursors. Comparisons will be maae between a simple system (one amino acid, one sugar) and a more complex system.


Sample Preparation


I. Simple 2-component systems Pipette 0.5 ml of 10% glucose solution into a test tube. The solutions will be reacted with amino acids at two temperatures, 100°C and 180°C. Only those marked with a "Y" are to be prepared. Add the designated amount of the following amino acids:

Amino Acid 	100°C 	180°C 	Weight ( mg ) 

_____________________________________________________ 



Valine	 	Y 	Y 		33 

Leucine 	Y 	Y 		36 

Methionine 	Y 			41 

Glutamine 	Y 	Y 		42 

Aspartic 	Y 			37 

Arginine 	Y 	Y 		59 

Phenylalanine 	Y 	Y 		46 

Lysine 			Y 		41 

No Amino Acids 		Y 		0

A. 100°C

Loosely attach the cap to the test tube. Boil for 45 min. in a water bath. The solution should be shaken after 30 min. to help solubilize any material adhering to the test tube wall. Some will not be soluble.


B. 180°C

Pour a layer of mineral oil (approx. 0.2 ml) on top of the amino acid/sugar solution. Cap the test tube lightly. Place in a 180°C oven for 5 min. Remove the tubes and allow them to cool thoroughly.


Each aroma should be identified with one of the following descriptors:

Violets 		Popcorn 

Potato 			Rock candy 

Sweet, chocolate 	Chocolate 

Caramel 		Rye bread 

Burnt cheese 		Chocolate 

Butterscotch

II. 3 Component Systems


A. Cooked Beef

Water 		0.3 ml 

D-Ribose 	15 mg 

Glutathione 	30 mg

B. Cooked Pork

Water 		0.3 ml 

D-Ribose 	3 mg 

L-Cysteine 	9 mg

React the above in the same manner as in IA.



III. Synthetic Meat Flavor Mixture

Components 		Wt in mg / 50 ml H20

________________________________________________________

Simple sugars 

	Glucose 		60 

	Ribose 			40 

	Xylose 			60 

Amino Acids 

	Glutamic Acid 		20 

	Cysteine 		20 

	Methionine 		11 

	Taurine 		22 

	Glycine 		8 

	Arginine 		6 

5 ' -Nucleotides 		25 

Gelatin 			500 

Salt (NaCl)			100 

_________________________________________________ 

The above mixture will be prepared by the instructor as a control. Each group is to choose 5 of the ingredients from the above formulation and give the instructor a list of them no later than the Monday prior to the laboratory. The samples will be autoclaved for 90 minutes. Evaluate the aromas of the samples. Report the descriptions of the aromas obtained from all formulations.

Questions


1. What is the effect of temperature on the types of reactions encountered in the two-component system.

2. How did your evaluation of aroma in Part I compare to that of Herz and Shallenberger (1960)?

3. In what types of products would synthetic meat flavors be used?

4. Read the article by Hsieh et al. (1980) and relate to the results of Section III.


References

1. MacLeod, G. and M. Seyyedain-Ardebili. 1981. Natural and simulated meat flavors (with particular reference to beef) CRC Critical Rev. in Food Sci. and Nutr., pp309-437

2. Morton, I. D., P. Akroyd and C. G. May. 1960. Flavoring substances and their preparation. U.S. Patent #836,694.

3. Herz, W. J. and R. S. Shallenberger. 1960. Some aromas produced by simple amino acid, sugar reactions. Food Res. 25(4):491.

4. Hsieh, Y. P. C., A. M. Pearson and W. T. Mag~e. 1980. Development of a synthetic meat flavor mixture by using surface response methodology. J. Food Sci. 45:112 5 .