Characterisation of in vitro gastrointestinal digests from low fat caprine kefir enriched with inulin

In vitro gastrointestinal digests from low fat caprines' milk kefir were characterised. The impact of the addition of different types of inulin (native, short-chain and long-chain) as a fat replacer on the subsequent release of peptides during digestion was also studied. A total of 52 peptides were identified, mainly from β-casein, following digestion. The gastrointestinal digests possessed angiotensin-converting enzyme (ACE)-inhibitory activity with IC50 values ranging from 190.71 ± 2.91 to 364.68 ± 31.27 μg protein mL−1. Among the identified peptides, four of them have been previously described as ACE-inhibitors (LHLPLP, HLPLP, DKIHP, MAIPPK), and the presence of these sequences can explain the moderate ACE-inhibitory activity found in the samples. Rheological analysis revealed that all manufactured kefirs exhibited shear-thinning behaviour. No significant effect of viscosity on protein degradation during simulated gastrointestinal digestion was found under the working conditions.