Table 4.

Protein oxidation measured by carbonyls in rendered by products without antioxidants for experiment 2 stored at 20 °C over extended storage

	Carbonyl*, nmol/mg protein			Time
Product†	Control	3 mo	6 mo	SEM	P-value
Beef
Spray dried plasma	7.1	8.5	9.4	1.2	0.41
Blood meal	17.4	29.8	22.0	4.3	0.16
Poultry
Blood meal	55.7b	87.2ab	123.1a	16.2	0.04

SEM, standard error of the mean. The analysis was conducted with five replicates at each time and protein source combination (n = 5). Differences in superscripts ^a–b within a row indicate a significant difference between time.

^*Carbonyls were analyzed as a measure of protein oxidation. Values are reported as nmol of carbonyl/mg of protein and are the average of five replicates.

^†Proteins were sourced from commercial renderers and did not contain antioxidants.