Effect of Glucosamine and Ascorbic Acid Addition on Beef Burger Textural and Sensory Attributes

Aside from the possible health benefit of dietary consumption of glucosamine (GlcN), studies have also reported its flavour enhancing properties in varying food products. However, the impact of its inclusion on other quality attributes of meat products has been under-assessed. The present study examined the effect of the addition of ascorbic acid (0.1%) and varying levels of GlcN (0.75, 1.5 and 3.0%) on colour stability, textural as well as sensory attributes of beef burger. Except for L* (lightness) value, significant interaction (p<0.01) between storage time and added ingredient was observed for all colour parameters (a*; redness, b*; yellowness, chroma, and hue angle) in beef burger. Generally, although ascorbic acid preserved the colour attributes of beef burgers during storage, addition of GlcN resulted in the deterioration of these colour parameters. Whereas the present result did not confirm any flavour enhancing attributes of GlcN compared to control, GlcN improved beef burger’s yield and reduced product cook loss. However, level of GlcN above 1.5% resulted in significant flavour and textural deterioration (p<0.05), leading to decline in consumer acceptability of beef burger. This study showed that a moderate level of glucosamine could be used in meat products as a functional ingredient with some additional technological benefits and limited impact on sensory attributes. Ascorbic acid adequately protected the colour of beef burger during refrigerated storage

Transport of the Glucosamine-Derived Browning Product Fructosazine (Polyhydroxyalkylpyrazine) Across the Human Intestinal Caco‑2 Cell Monolayer: Role of the Hexose Transporters

The transport mechanism of fructosazine, a glucosamine self-condensation product, was investigated using a Caco-2 cell model. Fructosazine transport was assessed by measuring the bidirectional permeability coefficient across Caco-2 cells. The mechanism of transport was evaluated using phlorizin, an inhibitor of sodium-dependent glucose cotransporters (SGLT) 1 and 2, phloretin and quercetin, inhibitors of glucose transporters (GLUT) 1 and 2, transcytosis inhibitor wortmannin, and gap junction disruptor cytochalasin D. The role of hexose transporters was further studied using downregulated or overexpressed cell lines. The apparent permeability (<i>P</i>_a,b) of fructosazine was 1.30 ± 0.02 × 10^–6 cm/s. No significant (<i>p</i> > 0.05) effect was observed in fructosazine transport by adding wortmannin and cytochalasin D. The presence of phlorizin, phloretin, and quercetin decreased fructosazine transport. The downregulated GLUT cells line was unable to transport fructosazine. In human intestinal epithelial Caco-2 cells, GLUT1 or GLUT2 and SGLT are mainly responsible for fructosazine transport

Retention time, MS and MS/MS data of the α-dicarbonyl compounds detected Mb-GlcN conjugates.

<p>Retention time, MS and MS/MS data of the α-dicarbonyl compounds detected Mb-GlcN conjugates.</p

Rapid Myoglobin Aggregation through Glucosamine-Induced α-Dicarbonyl Formation

<div><p>The extent of glycation and conformational changes of horse myoglobin (Mb) upon glycation with <i>N</i>-acetyl-glucosamine (GlcNAc), glucose (Glc) and glucosamine (GlcN) were investigated. Among tested sugars, the rate of glycation with GlcN was the most rapid as shown by MALDI and ESI mass spectrometries. Protein oxidation, as evaluated by the amount of carbonyl groups present on Mb, was found to increase exponentially in Mb-Glc conjugates over time, whereas in Mb-GlcN mixtures the carbonyl groups decreased significantly after maximum at 3 days of the reaction. The reaction between GlcN and Mb resulted in a significantly higher amount of α-dicarbonyl compounds, mostly glucosone and 3-deoxyglucosone, ranging from and 27 to 332 mg/L and from 14 to 304 mg/L, respectively. Already at 0.5 days, tertiary structural changes of Mb-GlcN conjugate were observed by altered tryptophan fluorescence. A reduction of metmyoglobin to deoxy-and oxymyoglobin forms was observed on the first day of reaction, coinciding with the greatest amount of glucosone produced. In contrast to native α-helical myoglobin, 41% of the glycated protein sequence was transformed into a β-sheet conformation, as determined by circular dichroism spectropolarimetry. Transmission electron microscopy demonstrated that Mb glycation with GlcN causes the formation of amorphous or fibrous aggregates, started already at 3 reaction days. These aggregates bind to an amyloid-specific dye thioflavin T. With the aid of α-dicarbonyl compounds and advanced products of reaction, this study suggests that the Mb glycation with GlcN induces the unfolding of an initially globular protein structure into amyloid fibrils comprised of a β-sheet structure.</p></div

Protein oxidation (carbonyl content) in Mb and Mb conjugated with GlcNAc, Glc and GlcN from 0 to 12 days.

<p>The results are mean ± standard deviation of three independent experiments. Data were fitted (except Mb-GlcN) with the non-linear fitting by GraphPad Prism software using following exponential equation: <i>y</i> = A(1-e<i>^-kt</i>), where <i>y</i> is the product concentration, A is the initial value at <i>t</i>₀, <i>k</i> is the reaction rate, and <i>t</i> is time.</p

Studies on the Formation of Maillard and Caramelization Products from Glucosamine Incubated at 37 °C

This experiment compared the in vitro degradation of glucosamine (GlcN), <i>N</i>-acetylglucosamine, and glucose in the presence of NH₃ incubated at 37 °C in phosphate buffer from 0.5 to 12 days. The reactions were monitored with UV–vis absorption and fluorescence emission spectroscopies, and the main products of degradation, quinoxaline derivatives of α-dicarbonyl compounds and condensation products, were determined using UHPLC-UV and Orbitrap mass spectrometry. GlcN produced two major dicarbonyl compounds, glucosone and 3-deoxyglucosone, ranging from 709 to 3245 mg/kg GlcN and from 272 to 4535 mg/kg GlcN, respectively. 3,4-Dideoxyglucosone-3-ene, glyoxal, hydroxypyruvaldehyde, methylglyoxal, and diacetyl were also detected in lower amounts compared to glucosone and 3-deoxyglucosone. Several pyrazine condensation products resulting from the reaction between dicarbonyls and GlcN were also identified. This study determined that GlcN is a significantly unstable molecule producing a high level of degradation products at 37 °C

(A) Fluorescence emission spectra; (B) far-UV spectra analyses; (C) secondary structure composition; (D) maximum fluorescence intensity of Thioflavin T (λ = 482 nm).

<p>The data points all have SD bars, but some are illegible and lie within the symbols; (E) transmission electron micrographs of native Mb and Mb incubated in the presence of GlcN at specific time points.</p

MALDI-TOF/TOF mass spectra of Mb incubated at 37°C for various times in the presence of GlcNAc, Glc and GlcN.

<p>Glycation adducts are marked with a star, with the number of stars corresponding to the number of adducts. Inset spectrum (A) shows the spectrum of GlcN incubated for 12 days in the region of m/z 6000–18000.</p

A deconvoluted ESI-MS spectra of Mb incubated at 37°C for various times in the presence of GlcNAc, Glc and GlcN.

<p>The experimental conditions were the same as those used to obtain the spectra in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139022#pone.0139022.g001" target="_blank">Fig 1</a>. Inset spectrum (A) shows the spectrum of GlcN incubated for 12 days in the region of 7000–18000 Da.</p