Chitin and its deacetylated derivative chitosan are natural polymers composed of randomly distributed-(1-4)linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Chitin is insoluble in aqueous media while chitosan is soluble in acidic conditions due to the free protonable amino groups present in the D-glucosamine units. Due to their natural origin, both chitin and chitosan can not be defined as a unique chemical structure but as a family of polymers which present a high variability in their chemical and physical properties. This variability is related not only to the origin of the samples but also to their method of preparation. Chitin and chitosan are used in fields as different as food, biomedicine and agriculture, among others. The success of chitin and chitosan in each of these specific applications is directly related to deep research into their physicochemical properties. In recent years, several reviews covering different aspects of the applications of chitin and chitosan have been published. However, these reviews have not taken into account the key role of the physicochemical properties of chitin and chitosan in their possible applications. The aim of this review is to highlight the relationship between the physicochemical properties of the polymers and their behaviour. A functional characterization of chitin and chitosan regarding some biological properties and some specific applications (drug delivery, tissue engineering, functional food, food preservative, biocatalyst immobilization, wastewater treatment, molecular imprinting and metal nanocomposites) is presented. The molecular mechanism of the biological properties such as biocompatibility, mucoadhesion, permeation enhancing effect, anticholesterolemic, and antimicrobial has been updated.

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High blood pressure is considered as a significant health problem worldwide. In addition to numerous preventive and therapeutic drug treatments, important advances have been achieved in the identification of dietary compounds that may contribute to cardiovascular health. Among these compounds, peptides with antihypertensive properties received special attention in the past 15 years. Although milk proteins are still the main source of antihypertensive peptides, recently a remarkable increase has been noticed in the report of antihypertensive peptides released from other dietary sources. Most of these peptides have demonstrated their properties by in vitro assays. However, the evidence for their beneficial antihypertensive effects has to be based on animal experiments and clinical trials. This paper reviews the current data of the blood pressure-lowering activity of food-derived peptides demonstrated in vivo (animal models and humans). Other aspects, such as the mechanism of action and bioavailability of these peptides which play a key role in their antihypertensive effects are also summarized in this review.

During the last decade, there has been a growing interest in understanding food's digestive fate in order tostrengthen the possible effects of food on human health. Ideally, food digestion should be studied in vivoon humans but this is not always ethically and financially possible. Therefore, simple in vitro digestionmodels mimicking the gastrointestinal tract have been proposed as alternatives to in vivo experiments.Thus, it is no surprise that these models are increasingly used by the scientific community, although theirvarious limitations to fully mirror the complexity of the digestive tract. Therefore, the objective of thisarticle was to call upon the collective experiences of scientists involved in Infogest (an internationalnetwork on food digestion) to review and reflect on the applications of in vitro digestion models, theparameters assessed in such studies and the physiological relevance of the data generated when comparedto in vivo data. The authors provide a comprehensive review in vitro and in vivo digestion studiesinvestigating the digestion of macronutrients (i.e. proteins, lipids and carbohydrates) as well as studies of the bioaccessibility and bioavailability of micronutrients and phytochemicals. The main conclusion is thatevidences show that despite the simplicity of in vitro models they are often very useful in predictingoutcomes of the digestion in vivo. However, this has relies on the complexity of in vitro models and theirtuning towards answering specific questions related to human digestion physiology, which leaves a vastroom for future studies and improvements

The angiotensin-converting enzyme (ACE)-inhibitory activity and antioxidant properties of a commercial fermented milk from Europe were evaluated. This dairy product showed moderate ACEinhibitory activity and ABTS • + radical-scavenging capacity. The peptides from most active fractions collected by reverse phase high-performance liquid chromatography (RP-HPLC) were sequenced by RP-HPLC-tandem mass spectrometry. This technique allowed rapid identification of peptides included in the most active fractions, and various potentially active peptides were recognised according to previous studies of structure-activity relationship. Three of the identified sequences had previously been described as potent ACE inhibitors. The structure of some sequences substantiated the presence of peptides with ACE-inhibitory, antioxidant and immunomodulatory activities.

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During the last decade, there has been a growing interest in understanding the fate of food during digestion in the gastrointestinal tract in order to strengthen the possible effects of food on human health. Ideally, food digestion should be studied in vivo on humans but this is not always ethically and financially possible. Therefore simple static in vitro digestion models mimicking the gastrointestinal tract have been proposed as alternatives to in vivo experiments but these models are quite basic and hardly recreate the complexity of the digestive tract. In contrast, dynamic models that allow pH regulation, flow of the food and injection in real time of digestive enzymes in the different compartments of the gastrointestinal tract are more promising to accurately mimic the digestive process. Most of the systems developed so far have been compared for their performances to in vivo data obtained on animals and/or humans. The objective of this article is to review the validation towards in vivo data of some of the dynamic digestion systems currently available in order to determine what aspects of food digestion they are able to mimic. Eight dynamic digestion systems are presented as well as their validation towards in vivo data. Advantages and limits of each simulator is discussed. This is the result of a cooperative international effort made by some of the scientists involved in Infogest, an international network on food digestion.

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