Fig. 4.

Changes in the redness index (a*/b* ratio) of beef samples during refrigerated storage. C: uncoated control, SC: the group coated with soy protein without essential oil addition. T1, T2, and T3: the isolated soy-protein-based edible coating solutions incorporated with 1, 2, and 3% thyme essential oils. O1, O2, and O3: the isolated soy-protein-based edible coating solutions incorporated with 1, 2, and 3% oregano essential oils. A–D: bars with different letters (within a storage day between groups) refer to statistically significant differences (p < 0.05). a–d: bars with different letters (within a group between storage days) refer to statistically significant differences (p < 0.05). Error bars represent standard errors