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Polyphenols are secondary metabolites of plants, commonly present in the human diet. Since they exhibit a wide range of bioactivities, polyphenols are extensively studied in the fields of nutrition and human health. Current studies have shown a high interest in determining the bioaccessibility of polyphenols, the amount of polyphenols that becomes available for absorption in the digestive tract. Bioaccessibility can be determined with the help of in vitro static gastrointestinal (GI) digestion models. In such a methodology, food samples containing polyphenols are subjected to a series of conditions that mimic the human gastrointestinal tract, with associated parameters. A high number of GI models with slightly different parameters were published. The purpose of this paper is to review the literature, focusing on the determination of polyphenol bioaccessibility and the parameters used in these GI digestion models, such as time, temperature, and pH of digestion, as well as enzyme concentrations. Gastrointestinal digestion models consist of oral, gastric and small intestine phases. These models provide a simple and reliable methodology which enables insight into the amount of bioaccessible polyphenols.

Polyphenols are secondary metabolites of plants, commonly present in the human diet. Since they exhibit a wide range of bioactivities, polyphenols are extensively studied in the fields of nutrition and human health. Current studies have shown a high interest in determining the bioaccessibility of polyphenols, the amount of polyphenols that becomes available for absorption in the digestive tract. Bioaccessibility can be determined with the help of in vitro static gastrointestinal (GI) digestion models. In such a methodology, food samples containing polyphenols are subjected to a series of conditions that mimic the human gastrointestinal tract, with associated parameters. A high number of GI models with slightly different parameters were published. The purpose of this paper is to review the literature, focusing on the determination of polyphenol bioaccessibility and the parameters used in these GI digestion models, such as time, temperature, and pH of digestion, as well as enzyme concentrations. Gastrointestinal digestion models consist of oral, gastric and small intestine phases. These models provide a simple and reliable methodology which enables insight into the amount of bioaccessible polyphenols. [ABSTRACT FROM AUTHOR]

The bioaccessibility property of apigenin from Mangifera indica (Water Lily var.) was investigated using in vitro gastrointestinal digestion model. Two digestion stages were simulated namely the gastric and small intestinal digestion by using different enzymes and physiological conditions that mimicked the digestion process. Following digestion, the bioaccessible apigenin was analysed using HPLD-DAD-MS. Results showed that the apigenin fraction in intestinal phase was higher than in gastric phase with amounts 1.03 ± 0.35 mg/100 g DW and 0.50 ± 0.08 mg/100 g DW, respectively. After 1 h exposure to gastric juice, the bioaccessibility of apigenin was 20.26 ± 3.06% with 79.74 ± 3.06% losses during the digestion, whereas in intestinal phase, the percentage of bioaccessibility significantly increased to 41.53 ± 13.99% and 58.47 ± 13.99% losses after 2 h treatment with pancreatin. It was concluded that the apigenin in Water Lily mango became bioaccessible, suggesting the absorption possibility of the compound in the upper part of intestine, which can lead to the health-related outcomes. [ABSTRACT FROM AUTHOR]

Rapid progress in gastroenterology during the first part of the last century has shown that gastrointestinal (GI) function is regulated by neuroendocrine, paracrine and endocrine signals. However, recent advances in chemical sensing, especially in the last decade, have revealed that free l-amino acids (AA), among other nutrients, play a critical role in modifying exocrine and endocrine secretion, modulating protein digestion, metabolism and nutrient utilization, and supporting the integrity and defense of the GI mucosa. Many of the mechanisms by which AAs elicit these functions in the GI has been linked to the traditional concept of hormone release and nervous system activation. But most these effects are not direct. AAs appear to function by binding to a chemical communication system such as G protein-coupled receptors (GPCRs) that activate signaling pathways. These intracellular signals, although their molecular bases are not completely elucidated yet, are the ones responsible for the neuronal activity and release of hormones that in turn regulate GI functions. This review aims to describe the distribution of the known GPCRs from the class 3 superfamily that bind to different kinds of AA, especially from the oropharyngeal cavity to the stomach, what kind of taste qualities they elicit, such as umami, bitter or sweet, and their activity in the GI tract. [ABSTRACT FROM AUTHOR]