• Abstract and Figures
• Public Full-text

Analytical Methods for Determining Bioavailability and Bioaccessibility of Bioactive Compounds from Fruits and Vegetables: A Review Juana M. Carbonell-Capella, Magdalena Buniowska, Francisco J. Barba, Mar´ıa J. Esteve, and Ana. Fr´ıgola Abstract: Determination of bioactive compounds content directly from foodstuff is not enough for the prediction of potential in vivo effects, as metabolites reaching the blood system may be different from the original compounds found in food, as a result of an intensive metabolism that takes place during absorption. Nutritional efficacy of food products may be ensured by the determination of bioaccessibility, which provides valuable information in order to select the appropriate dosage and source of food matrices. However, between all the methods available, there is a need to establish the best approach for the assessment of specific compounds. Comparison between in vivo and in vitro procedures used to determine bioaccessibility and bioavailability is carried out, taking into account the strengths and limitations of each experimental technique, along with an intensive description of actual approaches applied to assess bioaccessibility of bioactive compounds. Applications of these methods for specific bioactive compound’s bioaccessibility or bioavailability are also discussed, considering studies regarding the bioavailability of carotenoids, polyphenolic compounds, glucosinolates, vitamin E, and phytosterols. Keywords: bioaccessibility, bioactive compounds, bioavailability, in vitro methods, in vivo methods Introduction ever, comparison of results between different studies is difficult to Nowadays, consumers are more and more aware of the benefits accomplish, as there is no defined experimental model for study- beyond basic nutrition provided by food and food compounds. ing bioaccessibility and bioavailability. Analysis of the procedures Between these, plant foods including fruits and vegetables have for measuring or predicting bioactive compounds bioavailability is been demonstrated to exhibit multiple health benefits, closely re- therefore required, particularly as a result of continuous develop- lated to their high contents in vitamins and other bioactive com- ments of new products by food industries considered “functional” pounds (vitamin C, carotenoids, phenolic compounds, vitamin because of their specific antioxidant or phytochemical contents. E, glucosinolates) with antioxidant properties (Nehir and Sim- The aim of the present article is to critically review different ap- sek 2012; Barba and others 2013; Carbonell-Capella and others proaches used in the estimation of bioaccessibility and bioavailabil- 2013a). However, when studying the role of bioactive compounds ity of food compounds, focusing on bioactive compounds, as these in human health, their bioavailability is not always well known. are of major interest in current functional food development. Fur- Before becoming bioavailable, they must be released from the food thermore, results of studies in which bioaccessibility and bioavail- matrix and modified in the gastrointestinal (GI) tract. Therefore, ability of bioactive compounds were investigated are also discussed. it is important before concluding on any potential health effect, to analyze whether the digestion process affects bioactive compounds Bioaccessibility, Bioavailability, and Bioactivity and their stability, as this, in turn, will affect their bioavailability The concept of bioaccessibility can be defined as the quan- and their possible beneficial effects. tity or fraction which is released from the food matrix in the GI Different digestion models have been developed by the scientific tract and becomes available for absorption (Heaney 2001). This community that accurately mimic the complex physicochemical includes digestive transformations of food into material ready for and physiological conditions of the human GI tract, along with assimilation, the absorption/assimilation into intestinal epithelium in vivo models in living organisms (Hur and others 2011). How- cells, and lastly, the presystemic metabolism (both intestinal and hepatic). For some nutrients, beneficial effects of unabsorbed nu- trients (such as binding of bile salts by calcium in the tract) would MS 20131126 Submitted 08/9/2013, Accepted 10/17/2013. Authors are with Dept. of Nutrition and Food Chemistry, Univ. de Valencia,` Avda, Vicent Andres´ be missed by absorption-based definitions. Bioaccessibility is usu- Estelles,´ s/n. 46100 Burjassot, Spain. Direct inquiries to author Fr´ıgola (E-mail: ally evaluated by in vitro digestion procedures, generally simulating [email protected]). gastric and small intestinal digestion, sometimes followed by Caco- 2 cells uptake (Courraud and others 2013). C 2014 Institute of Food Technologists® r doi: 10.1111/1541-4337.12049 Vol.13,2014 ComprehensiveReviewsinFoodScienceandFoodSafety 155 Bioavailability of bioactive compounds . (hydrophilic/lipophilic), distribution in nature (specific to veg- etable species/ubiquitous), range of concentrations both in foods In vivo and in the human body, possible site of action, effectiveness against methodologies oxidative species, and specificity and biological action (Porrini and Riso 2008). Among them, polyphenolic compounds, carotenoids, tocopherols, phytosterols, and organosulfur compounds constitute important groups in the human diet. In vitro Indeed, bioavailability of bioactive compounds may be modified methodologies because of interactions with other macronutrients such as fiber in low-processed foods and beverages or proteins and polysaccharides in processed food products (Dupas and others 2006). Furthermore, when different foods come in contact in the mouth or digestive In vitro , ex vivo, and in tract, various interactions may take place affecting phytochemical vivo methodologies bioavailability (for example, fat enhances quercetine bioavailabilty in meals) (Lesser and others 2006). On that basis, significant re- search effort has recently focused on achieving optimal uptake of phytochemicals to maintain body functions and health and, con- Figure 1–Definition of bioavailability, bioaccessibility, and bioactivity and their potential assessment methodologies. sequently, carefully controlled studies are necessary in order to determine phytochemical bioavailability. As shown in Figure 2, different approaches to study bioacces- Differently, the term bioavailability includes also in its defini- sibility and bioavailability of bioactive compounds include in vitro tion the utilization of a nutrient and therefore can be defined methods, ex vivo techniques, in situ assays, and in vivo models. Ad- as the fraction of ingested nutrient or compound that reaches the vantages of each procedure are summarized in Table 1.However, systemic circulation and is utilized (Wood 2005). Overall, bioavail- comparisons between different approaches are difficult as condi- ability includes GI digestion, absorption, metabolism, tissue distri- tions differ between them and only in vivo studies provide accurate bution, and bioactivity. Consequently, in terms of bioavailability, values (Oomen and others 2002). when a claim is made, it must be demonstrated that the com- ponent analyzed is efficiently digested and assimilated and then, Approaches in the Assessment of Bioaccessibility once absorbed, exerts a positive effect in human health. How- and Bioavailability of Bioactive Compounds ever, practical and ethical difficulties are found when measuring Carotenoids bioactivity, so the term “bioavailability” is usually defined as the Carotenoids are found in fruits and vegetables as carotenes fraction of a given compound or its metabolite that reaches the (unsatured hydrocarbons) and xanthophylls (oxygenated deriva- systemic circulation (Holst and Williamson 2008), without con- tives). Generally, the main carotenoids in vegetables are lutein, sidering bioactivity. According to this definition, bioavailability of β-carotene, violaxanthin, and neoxanthin, whereas in fruits xan- a compound is determined in vivo in animals or humans as the thophylls are usually found in a greater proportion. They are prone area under the curve (plasma-concentration) of the compound to isomerization and/or oxidation due to their unsaturation (Hill obtained after administration of an acute or chronic dose of an and Johnson 2012). isolated compound or a compound-containing food (Rein and Only a very low proportion of carotenoids has been re- others 2013). ported to become bioaccesible (Courraud and others 2013). In Bioactivity is the specific effect upon exposure to a substance. It some fruits (such as mango, papaya) carotenoids are found in oil includes tissue uptake and the consequent physiological response droplets in chromoplast and hydroxycarotenoids are mostly esteri- (such as antioxidant, anti-inflammatory). It can be evaluated in fied with fatty acids, being more easily extracted during digestion. vivo, ex vivo,andin vitro (Figure 1)(Fernandez-Garc´ ´ıa and others Carotenoids bioavailability from foods varies greatly depending 2009). on endogenous (product-related) and exogenous (process-related) Meanwhile, digestibility applies specifically to the fraction of factors. Amount and type of fat present in the vicinity is a key food components that is transformed by digestion into potentially factor that affects bioaccessibility. A minimum amount of fat is accessible matter through all physical–chemical processes that take necessary for absorption (Fernandez-Garc´ ´ıa and others 2012), so place in the lumen.

Load more

  17

Copy Link