Fresh sika deer blood obtained by Shilu Co., Ltd, Changchun which had passed quarantine inspection and removed fibrous protein by stirring with a stick to avoid coagulation, then diluted two times with deionized water. The mixture was submerged in ice, then disrupted with ultrasound for 5 s by a 3 s interval for 15 min at the power of 500 watts. Enzymatic hydrolysis of deer bloodEnzyme, including pepsin (1:3000, CAS: 9001-75-6), trysin (250 U/mg, CAS: 9002-07-7) and alacase (200 U/mg, CAS: 9014-01-1) were purchased from Shanghai yuanye Bio-Technology Co., Ltd, Shanghai. The preparation of hydrolysates were according the method of the report (Zheng et al., 2019) with some modification. Specifically, the hydrolysis with pepsin (DBH-P) (enzyme/substrate ratio, 2%) was conducted at 40 o C and pH 2.0, trysin treatment (DBH-T) (enzyme/