• Delivery of β-carotene to the in vitro intestinal barrier using nanoemulsions with lecithin or sodium caseinate as emulsifiers

      Gasa-Falcon, Ariadna; Arranz, Elena; Odriozola-Serrano, Isabel; Martín-Belloso, Olga; Giblin, Linda; Ministerio de Economía y Competitividad; Enterprise Ireland; European Union; Science Foundation Ireland; Agencia de Gestio d’Ajuts Universitaris I de Recerca; et al. (Elsevier BV, 2021-01)
      To increase the intestinal delivery of dietary β-carotene, there is a need to develop nanostructured food systems to encapsulate this fat soluble bioactive. The aim of this study was to evaluate the bioacessibility and bioavailability across the intestinal barrier of β-carotene-enriched nanoemulsions stabilised with two emulsifiers (lecithin or sodium caseinate) by coupling an in vitro gastrointestinal digestion with two in vitro cell culture models (Caco-2 or co-culture of Caco-2/HT29-MTX). Nanoemulsions stabilised with lecithin had significantly higher β-carotene in the gastrointestinal digested micellar fraction, lower β-carotene in the Caco-2 (and Caco-2/HT29-MTX) apical compartment and significantly higher β-carotene in Caco-2 cellular content compared to β-carotene-enriched nanoemulsions stabilised with sodium caseinate. Finally, to assess anti-inflammatory activity of digested nanoemulsions, lipopolysaccharide stimulated macrophages were exposed to Caco- 2 basolateral samples with levels of TNF-α and IL-β, subsequently quantified. A TNF-α response from stimulated THP-1 macrophages was elicited by basolateral samples, regardless the emulsifier used to formulate nanoemulsions. This study demonstrated that β-carotene permeability is influenced by the food derived emulsifier used for stabilising nanoemulsions, indicating that composition may be a critical factor for β-carotene delivery.
    • Simulated gastrointestinal digestion of nisin and interaction between nisin and bile

      Gough, Ronan; O'Connor, Paula M.; Rea, Mary; Gomez-Sala, Beatriz; Miao, Song; Hill, Colin; Brodkorb, Andre; Department of Agriculture, Food and the Marine; Teagasc Walsh Fellowship Programme; 10/RD/TMFRC/701 (Elsevier, 2017-08-14)
      Nisin, an antimicrobial peptide showing activity against many Gram positive bacteria, is widely used as a food preservative. The simulated gastrointestinal digestion of nisin (variant A) was studied using the in vitro INFOGEST digestion method. Following oral, gastric and small intestinal digestion, there was no intact nisin in the system and the nisin was primarily digested by pancreatin. After digestion, six nisin fragments (1–11, 1–12, 1–20, 1–21, 1–29 and 1–32) were identified by reversed phase high performance liquid chromatography and mass spectroscopy and four of these nisin fragments (1–20, 1–21, 1–29 and 1–32) demonstrated low antibacterial activity against Lactococcus lactis HP in agar diffusion activity assays. Additionally, it was observed that bile salts form a complex with nisin. This was examined by atomic force microscopy, turbidity and dynamic light scattering, which showed that this interaction resulted in significantly larger bile salt micelles. The presence of bile salts at physiological levels significantly altered the relative amounts of the nisin fragments 1–12, 1–20 and 1–29 produced during an in vitro digestion. This study highlights the importance of including bile in simulated digestions of antimicrobial peptides in order to obtain a more accurate simulation of the in vivo digestion products and their activity.