Zinc bioaccessibility is affected by the presence of calcium ions and degree of methylesterification in pectin-based model systems

Abstract

Minerals are required by the human body to perform physiological functions. Mineral deficiencies, often caused by low mineral bioaccessibility in plant-based foods, are a matter of great concern all over the world. Several antinutrients (e.g. pectin) may contribute to this reduced mineral bioaccessibility by formation of indigestible complexes due to mineral binding. Structural characteristics of the antinutrients, as for instance the degree of methylesterification (DM) in the case of pectin, may play a role in this mineral binding phenomenon and has been evaluated before, however, only in single mineral model systems. In natural food systems, several mineral types are present together which may affect each other's bioaccessibility. Therefore, this study investigated the influence of the presence of Ca 2+ on Zn 2+ binding capacity and bioaccessibility in mineral-pectin model systems with different DM. The results showed that increasing Ca 2+ concentration and pectin DM reduces the Zn 2+ binding capacity of pectin and consequently increases Zn 2+ bioaccessibility in the in vitro small intestine. Moreover, the in vitro digestion procedure with adjustment of pH only, no addition of enzymes, bile salts nor digestive fluids during simulation of gastric and small intestinal phases, was found to be most appropriate to fundamentally study the influence of pectin DM and presence of Ca 2+ on Zn 2+ bioaccessibility in mineral-pectin model systems. Keywords Citrus pectin, degree of methylesterification, mineral (Ca 2+ and Zn 2+) competition, Zn 2+ binding capacity, Zn 2+ bioaccessibility. number of macromolecules and for more than 300 enzymatic reactions (Gharibzahedi & Jafari, 2017; Jackson & Lowe, 1992). Low zinc blood levels may lead to numerous clinical symptoms, such as growth retardation, impaired brain development and cognitive performance, poor wound healing, diarrhoea, infertility or increased risk of infections (Wapnir, 2000). One of the major contributing factors towards mineral deficiencies is inadequate intake, as minerals cannot be synthesized by the human body and therefore must be obtained from the diet. Inadequate mineral intake can be attributed to low amounts in the ingested food or low mineral bioaccessibility (BAC) from the consumed food products (Platel & Srinivasan, 2015). The term bioaccessibility is defined as the fraction of a nutrient which is released from the food matrix into the gastrointestinal tract through the digestion process and that becomes available for intestinal absorption (Carbonell-Capella, Buniowska, Barba, Esteve, & Frígola, 2014). In plant-based foods, mineral BAC can be reduced due to the presence of several mineral antinutrients (Platel & Srinivasan, 2015), including dietary fibers, phytic acid or polyphenols. These mineral antinutrients can bind in situ minerals, minerals which are added to the food or minerals originating from other simultaneously ingested food ingredients, thereby potentially reducing the mineral release for intestinal absorption (Kumar, Sinha, Makkar, & Beck...

Ageing, dehulling and cooking of Bambara groundnuts: consequences for mineral retention and in vitro bioaccessibility

“…43 While these have different abilities for binding minerals, different minerals bind to varying extents to one antinutrient as well. 44 Typically, Fe is known to be strongly chelated to phytic acid in legumes and cereal seeds. 12 Based on our observations discussed above, it was found that Mg and Zn seem to be relatively loosely bound to antinutrients in milled Bambara groundnuts, given their ease of solubility.…”

Unravelling scientific research towards the green extraction of phenolic compounds from leaves: a bibliometric analysis

“…However, the study of the bioaccessibility as well as bioavailability of these incorporated extracts is of paramount importance. Bioaccessibility refers to the fraction of nutrient released from the food matrix into the gastrointestinal tract after digestion which becomes available for absorption through the intestine (Rousseau et al ., 2019). Bioavailability refers to the quantity of nutrient that has been digested as well as absorbed and then available for the metabolic functions (Bosscher et al ., 2003).…”

A stable isotope approach to accurately determine iron and zinc bioaccessibility in cereals and legumes based on a modified INFOGEST static in vitro digestion method

“…In this study, we did not investigate the binding effect of the enzymes and bile salts individually, as such it was not possible to determine whether the binding effect was from specific enzymes or bile salts or their combination. Although Rousseau et al (2019) found a zinc binding effect from bile salts and not from enzymes, they used different enzymes to ours such that an enzyme binding effect cannot be ruled out, especially from pancreatin which was particularly difficult to dissolve. The iron and zinc binders present in the reagent blank are most likely associated with the pancreatin and bile considering their high iron and zinc contribution to the gastrointestinal digesta.…”

“…Saturated solutions of pancreatin and bile are used in the INFOGEST method as is, and these precipitate during centrifugation with the potential to adsorb metals into the solid phase. Rousseau et al (2019), showed that zinc bioaccessibility was drastically reduced when the complexity of the in vitro digestion model was increased by adding bile salts in comparison to enzymes which had no effect. They concluded that bile salts may interact with zinc thereby reducing zinc bioaccessibility.…”