Scores for discolouration of beef patties are shown in Table 2.
Discolouration increased significantly in all treatments throughout the storage period.
However, samples with rosemary+ascorbic acid presented lower scores than those with any other treatment for the whole 20 days of storage at 2°C.
At day 20 of storage, beef patties with rosemary+ascorbic acid had the lowest loss of redness, as already discussed regarding its CIE a* value ( Fig. 1); a score of three corresponds to 10–20% of discolouration, which may be considered acceptable to consumers (Greene et al., 1971).
Treatment with rosemary alone was the next in inhibiting discolouration, 20–60% at day 16 of storage.
Control and samples with taurine exhibited early discolouration.
Results for the 8th day clearly showed that at that time only beef patties with rosemary and carnosine, irrespective of the presence of ascorbic acid, presented scores of three or below, while all other treatments would be considered unacceptable by consumers.
These results were in agreement with those found for metmyoglobin formation.