The vast amount of feathers generated (>1 Mtons/a in Europe) in the poultry industry is an opportunity of upcycling by-product materials and improving sustainable practices. Feathers are potentially interesting materials as feed protein ingredients due to their high protein (>85 wt%) and cystine content (>7 wt%). However, due to their challenging recalcitrant nature, they have to be processed to make feather protein suitably digestible. The objective was to investigate the effects of temperature (120^oC–160^oC) and time (10, 30, and 60 min) in thermal pressure hydrolysis of feathers on availability for enzymatic hydrolysis (AEH) and cystine conservation. AEH is defined as degree of degradation of processed feather protein by two digestive enzymes pepsin and pancreatin (Boisen). The present study identified and assessed four temperature stages that take place during feather processing. The four temperature stages are 120^oC–135^oC, 140^oC–155^oC, > 160^oC, and the cooling-down phase. The second stage has the greatest influence on AEH. As well as temperature, hydrolysis time is also an essential parameter that had a major impact in the second stage (140^oC–155^oC). Both temperature and time influence negatively cystine content and stability. The present study demonstrates for the first time the importance of four reaction stages during feather hydrolysis and the impact of four stages on AEH of the obtained products.

家禽业产生的大量羽毛（在欧洲超过1吨/年）是升级副产品材料和改善可持续性实践的机会。羽毛由于其高蛋白（> 85 wt％）和胱氨酸含量（> 7 wt％）而成为饲料蛋白成分中潜在的有趣材料。但是，由于它们具有挑战性的顽固性，因此必须对其进行加工以使羽毛蛋白适合于消化。目的是研究温度（120 ^o C–160 ^oC）和在热压条件下水解羽毛的时间（10、30和60分钟），以保证酶促水解（AEH）和胱氨酸的保存。AEH定义为两种消化酶胃蛋白酶和胰酶（Boisen）对加工羽毛蛋白的降解程度。本研究确定并评估了羽毛加工过程中发生的四个温度阶段。四个温度阶段分别是120 ^o C–135 ^o C，140 ^o C–155 ^o C，> 160 ^o C，以及冷却阶段。第二阶段对AEH影响最大。除温度外，水解时间也是第二阶段（140 ^o C–155 ^oC）。温度和时间都对胱氨酸含量和稳定性产生负面影响。本研究首次证明了羽毛水解过程中四个反应阶段的重要性以及四个阶段对所得产品AEH的影响。