Optimizing polyphenol bioaccessibility: the impact of freeze-drying on chlorogenic acid stability in vitelotte potatoes

Chlorogenic acids (CGAs) are widely recognized for their antioxidant and metabolic-modulating properties; however, their stability during digestion largely depends on the food matrix and processing conditions. In this study, a freeze-dried matrix of Solanum tuberosum L. cv. Vitelotte was utilized to assess the impact of lyophilization on CGA retention and controlled release. A standardized in vitro digestion model was combined with multi-analytical techniques (HPLC-UV-DAD, UHPLC-HRMS, UV-Vis spectroscopy) to evaluate the fate of CGAs during gastrointestinal transit. The results demonstrate that lyophilization significantly enhances CGA stability by minimizing oxidative degradation and modulating their bioaccessibility through interactions with potato starch. Compared to fresh matrices, freeze-drying preserved the structural integrity of three major caffeoylquinic acid isomers, which remained chemically stable up to the intestinal phase. The protective effect of starch–polyphenol interactions likely contributed to a more controlled bioaccessibility, preventing abrupt losses in phenolic content. Unlike CGAs, anthocyanins exhibited lower bioaccessibility, confirming their pH-dependent instability. These findings underscore the importance of sample preparation methods in polyphenol bioaccessibility studies and highlight the potential of lyophilization as a strategy to optimize the nutritional value of CGA-rich functional foods.