Effect of cow milk on the in vitro bioaccessibility of coffee chlorogenic acids

To study the effect of cow milk on coffee chlorogenic acids (CQAs) bioaccessibility during simulated gastro-intestinal digestion, 50% coffee with 50% water (C), or with 50% whole milk (CM50), or with 25% whole milk-25% water (CM25), or with 10% whole milk- 40% water (CM10), or with 50% semi-skimmed milk (CSSM50), or with 50% skimmed milk (CSM50) were digested in sequence with pepsin (300 U/ml; pH 3; 2h) then with pancreatin (0.8 g/l; pH 7.5; 2h) and bile salts (5 mg/ml). At the end of the digestion periods, samples were subjected to ultrafiltration and the low molecular weight fractions were analyzed with LC-MS. The bioaccessible CQAs decreased from 91.4 ± 1.3 to 85.2 ± 5.4 and to 61.2 ± 2.0 micromol/100ml at the end of gastric and intestinal digestions respectively in sample C, suggesting CQAs degradation. After the two digestion periods higher recovery of CQAs were obtained with CM50, CM25, CM10 and CSSM50 samples respect to C. For example at the end of the digestion periods, the bioaccessible CQAs in CM50 and CSSM50 were 80.0 ± 4.6 and 67.7 ± 1.0 micromol/100 ml respectively. Similar results were obtained with 5-caffeoylquinic acid. These data suggest that the milk fats have a protective effect on CQAs degradation during digestion.