Table 2. Analysis of variance for the effects of enzymatic hydrolysis conditions and their interactions on DPPH radical scavenging activity of tuna cooking juice concentrate hydrolysate
| Sources | Sum of squares | df | Mean square | F-value | p-value |
| Model | 860.30 | 5 | 172.06 | 13.42 | 0.002 |
| X1 | 19.48 | 1 | 19.48 | 1.52 | 0.257 |
| X2 | 494.58 | 1 | 494.58 | 38.59 | 0.000 |
| X1X1 | 224.47 | 1 | 224.47 | 17.51 | 0.004 |
| X2X2 | 162.51 | 1 | 162.51 | 12.68 | 0.009 |
| X1X2 | 3.25 | 1 | 3.25 | 0.25 | 0.630 |
| Lack of fit | 65.82 | 3 | 21.94 | 3.67 | 0.121 |
| Pure error | 23.90 | 4 | 5.97 | | |
| Total | 950.02 | 12 | | | |
| R2 | 0.9056 | | | | |
| CV | 15.06% | | | | |
X1 = Alcalase concentration (%) and X2 = hydrolysis time (min).
DPPH, 2,2-diphenyl-1-picrylhydrazyl; CV, coefficient of variation.