Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Food Technology


Dawson, Paul L.

Committee Member

Scott , Thomas R.

Committee Member

Northcutt , Julie K.

Committee Member

Bridges , William C.


Four separate studies were conducted to examine carnosine levels and associated antioxidant activity in poultry co-products, in rendered poultry protein meal, in tissues from stressed or non-stressed chickens. In the first study, carnosine was extracted from poultry co-products (head, liver, lungs, tail, gizzard, brain and heart). Liver contained the highest (102.29 mg/gm) level, while brain contained the lowest level of carnosine (0.95 mg/gm). Except brain, all tissue ultrafiltrates (20.87-39.57%) and reconstituted dry powders (5.66- 14.47%) showed thiobarbituric reactive acid species (TBARS) inhibition. Head ultrafiltrate and reconstituted dry powder showed maximum while gizzard showed the minimum metal chelating activity. Free radical scavenging activity of ultrafiltrate of all tissues samples ranged from 25.1 to 79.4% while this activity was higher (29.8 to 84.1%) in the reconstituted dry powder of all tissue samples. Oxygen radical absorbing capacity (ORAC) values were highest in liver ultrafiltrate and lowest in heart. Results indicated that carnosine was present in all the tissue samples investigated and their ultrafiltrates as well as dry powders of tissue samples possess antioxidant properties.
In the second study examining poultry protein meal, carnosine content of sample-G was almost 2.6 times higher than sample-A. TBARS inhibition by sample-G was 15.9% while Sample-A did not exhibit any TBARS inhibition. Metal chelating activity and free radical scavenging activities of sample-A and sample-G did not differ. ORAC values (µM Trolox Equivalents /gm of dry sample) of sample-A (84.4) were greater than sample-G (68.4).
The third study determined carnosine levels in different tissues of broilers under stress versus non-stress conditions. Corticosterone levels of stressed broilers (24.36 ng/ml) was 10 fold higher (p=0.002) than non-stressed broilers (2.28 ng/ml). There was significant increase in carnosine content in breast tissue of stressed birds (17.39 mg/gm), and was 10 times (p=0.005) more than non-stressed birds (1.85 mg/gm). Carnosine content in thigh of stressed birds (21.25 mg/gm) was approximately 2 fold higher (p=0.001) than non-stressed birds (11.10 mg/gm). Carnosine content in brain of stressed birds did not differ (p=0.82) from that in non-stressed birds. Results indicated that carnosine may play a significant role in muscles during short term stress.
In fourth study, it was determined that TBARS inhibition and metal chelating activity of carnosine was due to the imidazole ring present in the histidine while free radical scavenging activity of carnosine was attributed to histidine amino acid.
Overall, conclusions were drawn that poultry byproducts, poultry protein meal contains carnosine and exhibited antioxidant properties. These antioxidant properties were due to carnosine's unique structure. Lastly, stress increases the carnosine levels in breast and thigh tissues of broilers.

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