Table 5. Treatment effects on muscle cooking loss (%), shear force (N), hydroxyproline content (µg/mg wet tissue), pH value, cathepsin activities (U/g muscle) and lactate content (mmol/g protein) in grass carp.
Dietary isoleucine levels (g/kg diet) | ||||||
3.8 | 6.6 | 9.3 | 12.5 | 15.2 | 18.5 | |
Cooking loss | 15.09±1.22c | 13.87±1.25b | 12.62±0.81a | 12.20±0.98a | 13.20±0.30ab | 15.42±0.66c |
Shear force | 1.855±0.119ab | 1.958±0.098bc | 2.232±0.156d | 2.022±0.152c | 1.972±0.123bc | 1.723±0.118a |
Hydroxyproline | 0.240±0.021bc | 0.247±0.022c | 0.327±0.012d | 0.263±0.022c | 0.222±0.017ab | 0.203±0.016a |
pH | 5.992±0.028a | 6.045±0.034bc | 6.080±0.029c | 6.050±0.053bc | 6.035±0.040abc | 6.033±0.019ab |
Cathepsin B | 5.923±0.642b | 5.445±0.479b | 4.420±0.385a | 4.697±0.518a | 5.644±0.545b | 5.838±0.502b |
Cathepsin L | 1.218±0.130b | 1.138±0.121b | 0.991±0.100a | 1.000±0.091a | 1.093±0.100ab | 1.114±0.083b |
Lactate | 4.146±0.355d | 3.829±0.228c | 2.269±0.169a | 2.476±0.216a | 3.504±0.245b | 3.950±0.274cd |
Regression | ||||||
Ycooking loss = 0.115×2−3.108x+33.402 | R2 = 0.854 | P = 0.056 | ||||
Yshear force = −0.006×2+0.13x+1.440 | R2 = 0.830 | P = 0.070 | ||||
YpH = −0.001×2+0.023x+5.930 | R2 = 0.684 | P = 0.177 | ||||
Ycathepsin B = 0.023×2−0.499x+7.501 | R2 = 0.738 | P = 0.134 | ||||
Ycathepsin L = 0.003×2−0.073x+1.456 | R2 = 0.824 | P = 0.074 | ||||
YLactate = 0.029×2−0.66x+6.385 | R2 = 0.745 | P = 0.128 |
Values are means ± SD (n = 6), and mean values within the same row with different superscripts are significantly different (P<0.05).