Evaluation of bioaccessibility of bioactive compounds in ready-to-eat refrigerated and frozen broccoli using in vitro digestion models

Refrigerated and frozen ready-to-eat cooked vegetables are becoming increasingly popular with consumers and catering services. Simulating digestion is essential for accurately assessing the nutritional value of ready-to-eat vegetables, as raw composition data alone may overestimate their health benefits. Therefore, this study evaluated the bioaccessibility of bioactive compounds in broccoli after heat treatment, storage, and in vitro gastrointestinal digestion. Fresh broccoli (FB) and heat-treated (boiled or steamed) broccoli were subjected to refrigerated (RBB, RSB) or frozen (FBB, FSB) storage. FB exhibited high phenol (610 mg GAE/100 g) and flavonoid (295 mg QE/100 g) contents. Thermal treatment significantly decreased the phenolic content to 503, 515, 368, and 393 mg GAE/100 g in RBB, RSB, FBB, and FSB, respectively. Total phenols, flavonoids, vitamin C, antioxidant capacity, dietary fibers, and phenolic profiles were analyzed before and after in vitro gastrointestinal digestion. After in vitro gastrointestinal digestion, phenol, flavonoid, and vitamin C contents decreased significantly compared to those after digestion with FB (DFB). No significant changes in total, soluble (SDF), or insoluble (IDF) dietary fiber were observed between heat-treated broccoli and FBs. However, in vitro, gastrointestinal digestion of FB decreased SDF from 1.84 to 1.59% and increased IDF from 1.02 to 1.3%. HPLC analysis revealed substantial phenolic compound losses after in vitro gastrointestinal digestion, ranging from 64.9% in DFB to 88% in DFBB. After digestion, the recovery of bioactive compounds decreased, particularly for vitamin C and phenolics. These findings emphasize the importance of simulating digestion when evaluating the nutritional value of processed vegetables, as relying solely on raw composition data may overestimate health-promoting compound intake. Therefore, dietary recommendations should consider cooking methods and the loss of bioactive substances during digestion. Further research is needed to gain deeper insights into the bioaccessibility of antioxidant compounds after the digestion of cooked and preserved vegetables.