Iron (Fe²⁺)-Catalyzed Glucosamine Browning at 50 °C: Identification and Quantification of Major Flavor Compounds for Antibacterial Activity

Abstract

Glucosamine browning at 50 °C with (GlcN/Fe(2+)) or without iron (GlcN) was studied over time from 0 to 48 h. Generation of reactive oxygen species (ROS), H2O2, and (1)O2, along with α-dicarbonyls, fructosazine, and deoxyfructosazine, was evaluated. Singlet oxygen generation increased over time and was greater in GlcN/Fe(2+) caramel solution. The presence of iron significantly increased the concentration of α-dicarbonyls at an early incubation time (3 h). Fructosazine and deoxyfructosazine were the major degradation products at 48 h comprising together up to 37 and 49% in GlcN and GlcN/Fe(2+), respectively. GlcN/Fe(2+) (48 h) exhibited a MIC50 against highly heat-resistant Escherichia coli AW 1.7 at pH 5, but not at pH 7. Despite several antimicrobial compounds being produced during browning, GlcN/Fe(2+) created a synergistic environment for the fructosazine-organic acids to confer their antimicrobial activity. GlcN caramel solutions have the potential to serve as both flavoring compounds and antimicrobial agents in formulated food systems.

Evidence to indicate that maillard reaction products can provide selective antimicrobial activity

“…Other works has demonstrated alterations of specific virulence regulators of known food pathogens when in the presence of model MRPs [36]. Accelerated non-enzymatic browning reaction, using a glucosamine/Fe 2+ complex to generate singlet oxygen and reactive alpha dicarbonyls, will lower MIC 50 values against heat-resistant E.coli at acidic rather than neutral pH [30]. High molecular weight (>10 kDa) melanoidins have also been identified as active MRPs with effective antimicrobial activity that have the potential to induce irreversible damage of cell membrane permeability and function [12,20].…”

“…The antibacterial activity could therefore be provided by the generation of a hydroxyl radical from the Fenton Reaction that involves ferrous ion interacting with hydrogen peroxide. Recently, glucosamine browning in the presence of ferrous ion displayed antimicrobial activity towards heat resistant at pH 5, but not pH 7, thus showing the importance of maintaining ferrous ion solubility to initiate reactivity with nonenzymatic browning precursors that generate alpha dicarbonly and hydrogen peroxide byproducts; candidates for the observed antimicrobial activity [30].…”

“…In the example with yeast, (Saccharomyces cerevisiae), it was reported that the active MRP component was furfural, which inhibited glycolysis and also alcohol product, due to inhibitory action on key enzymes, especially the dehydrogenases. Potential of MRPs to inhibit growth of food-borne pathogens has also attracted considerable attention [20,29,30]. Of particular interest is that some conditions employed to generate MRPs exhibiting antioxidant intermediates that otherwise occur if the pH is basic, and directed through a 2,3-enolization reaction.…”

Inhibitory activity of a Concanavalin-isolated fraction from a glucosamine-peptides reaction system against heat resistant E. coli

“…Gottardi et al (2014) came to the same conclusion and reported that GlcN-glycated gluten hydrolysates could inhibit the growth of E. coli at 40 mg/mL, but not B. subtilis . It is expected that these antimicrobial activities are not only due to the glycopeptides alone, but also due to other chemical compounds produced, including GlcN-derived α-DCs and the GlcN self-condensation products fructosazine and deoxyfructosazine (Hrynets et al, 2016; Bhattacherjee et al, 2016). Indeed, recent studies have shown that fructosazine was able to inhibit 50% of the growth of extremely heat-resistant E. coli AW 1.7 at 3.6 g/L at pH 5 (Hrynets et al, 2016; Bhattacherjee et al, 2016).…”

“…It is expected that these antimicrobial activities are not only due to the glycopeptides alone, but also due to other chemical compounds produced, including GlcN-derived α-DCs and the GlcN self-condensation products fructosazine and deoxyfructosazine (Hrynets et al, 2016; Bhattacherjee et al, 2016). Indeed, recent studies have shown that fructosazine was able to inhibit 50% of the growth of extremely heat-resistant E. coli AW 1.7 at 3.6 g/L at pH 5 (Hrynets et al, 2016; Bhattacherjee et al, 2016). Here fructosazine exerted its antimicrobial action by permeabilizing the cell membrane, damaging membrane integrity and fragmenting DNA.…”