Table 1.

Proximate composition of salmon heads and hake by-products (ww) and protein hydrolysates prepared from salmon heads (HPS, dw) and hake by-products (HPH, dw) with Alcalase, and degree of hydrolysis (DH) and protein yield of the hydrolysis process.

	Protein (%)	Moisture (%)	Ash (%)	Fat (%)	DH (%)	Protein Yield (%)	Hydrolysis Yield (%)
Salmon heads	13.8 ± 0.9 A	61.2 ± 0.5 A	2.39 ± 0.19 A	19.8 ± 0.2 B	---	---
Hake by-products	14.3 ± 1.4 A	81.6 ± 0.0 B	2.76 ± 0.13 B	0.5 ± 0.0 A	---	---
HPS	75.6 ± 0.9 a	7.6 ± 0.5 b	13.45 ± 0.31 a	2.1 ± 0.1 a	26.2 ± 0.2 b	68.1 ± 2.3 a	32.4 ± 2.3 a
HPH	76.8 ± 0.5 a	4.4 ± 0.1 a	16.69 ± 0.16 b	2.7 ± 0.0 b	20.3 ± 0.0 a	75.5 ± 3.4 b	76.4 ± 3.4 b

Different lowercase (a, b) letters in each column indicate significant differences (p < 0.05) between FPH. Different uppercase (A, B) letters in each column indicate significant differences (p < 0.05) between raw materials.