1

8.88 ± 0.06^a

7.57 ± 0.01^a

7

8.75 ± 0.04^b

6.99 ± 0.04^b

14

8.56 ± 0.05^c

6.31 ± 0.09^c

21

8.27 ± 0.07^d

5.47 ± 0.07^d

28

7.95 ± 0.08^e

4.57 ± 0.07^e