Forskning

November 1, 2012

The type and concentration of milk increases the in vitro bioaccessibility of coffee chlorogenic acids

D Tagliazucchi et al, The type and concentration of milk increases the in vitro bioaccessibility of coffee chlorogenic acids, Journal of Agricultural and Food Chemistry, published online ahead of print.

ABSTRACT:
Coffee with different types and concentrations of milk was digested with pepsin (2 h) and pancreatin (2 h) to simulate gastropancreatic digestion. Chlorogenic acids (CGAs) were determined by high-performance liquid chromatography− electrospray ionization−tandem mass spectrometry in ultrafiltrate (cutoff 3 kDa) to evaluate their bioaccessibility. After digestion, bioaccessible CGAs decreased from 80.2 to 53.0 and 69.5 μmol/200 mL in coffee without milk and coffee-whole milk, respectively. When whole, semi skimmed, skimmed, or diluted milk were present, the increase in bioaccessibility was dependent on fat content (r = 0.99, p < 0.001). No relationship was observed between bioaccessibility and proteins, carbohydrates, and calcium content. The addition of milk to coffee caused an immediate decrease in the bioaccessibility due to CGAs binding to proteins. After digestion, 86−94% of bound CGAs remained in the high molecular weight fraction. Casein bound 5-caffeoylquinic acid with high affinity (KD of 37.9 ± 2.3 μmol/L; n = 0.88 ± 0.06).