highly significantp < 0.01
(7) T a n n i n = + 2.896 − 0.0766 A − 0.116 B − 0.0583 C − 0.0161 D − 0.0550 A B + 0.0008 A C − 4.3108 A D + 0.0006 B C + 0.0004 B D − 4.6296 C D + 0.0283 A 2 + 0.0533 B 2 + 0.0004 C 2 + 0.0001 D 2 The results of the statistical analysis indicated that the effects of incubation time (D) and quadratic model terms (C 2 and D 2 ) on tannin content were highly significant at p < 0.01.