Small collagen peptides are associated with various benefits, such as bone and skin health. However, preparation of small collagen peptides from terrestrial vertebrate origins remains a challenge. Here, we show that pretreatment with formic acid enhanced the production of small collagen peptides from spent hen skin. After pretreatment with formic acid, the percentage of small peptides below 2 kDa increased to 48.92% and 43.34% from 33.79% and 36.32% for heat-soluble collagen (HSC) and pepsin-soluble collagen (PSC), respectively. Pretreatment with formic acid degraded telopeptides and released the cross-links (pyrrole and pyridinoline), which made hen collagen more susceptible to papain hydrolysis. LC-MS/MS results revealed that none of the peptides identified from HSC-FA (formic acid)-Papain and PSC-FA-Papain were derived from cross-linked telopeptides. These results demonstrated that formic acid assisted the hydrolysis of highly cross-linked collagen of spent hens, and it might also be used to produce small collagen peptides from other aged, vertebrate collagens.

小胶原蛋白肽具有多种益处，例如骨骼和皮肤健康。然而，从陆生脊椎动物起源制备小的胶原蛋白肽仍然是一个挑战。在这里，我们显示了用甲酸进行的预处理增强了用过的母鸡皮肤中小的胶原蛋白肽的产生。用甲酸预处理后，低于2 kDa的小肽比例从热溶性胶原蛋白（HSC）和胃蛋白酶溶性胶原蛋白（PSC）的33.79％和36.32％分别增加到48.92％和43.34％。用甲酸预处理会降解端肽并释放出交联键（吡咯和吡啶啉），从而使母鸡胶原蛋白更容易受到木瓜蛋白酶水解的影响。LC-MS / MS结果表明，从HSC-FA（甲酸）-木瓜蛋白酶和PSC-FA-木瓜蛋白酶中鉴定出的肽均未衍生自交联的端肽。这些结果表明，甲酸有助于水解废母鸡的高度交联的胶原蛋白，并且它还可用于从其他老化的脊椎动物胶原蛋白中生产小的胶原蛋白肽。