8:30 am - 9:30 am
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Fuyao Zou. This seminar is open to the general public to attend.
Meeting ID: 848 1024 2999 | Passcode: mZsBE0
Thesis Topic: The effect of UV light and spray drying on glucosamine non-enzymatic browning
MSc with Dr. Mirko Betti.
Glucosamine (GlcN) is an amino monosaccharide that contains both an amino group and a carbonyl group. It is capable of undergoing non-enzymatic browning at lower temperatures, generating a plethora of desirable compounds, including α-dicarbonyl compounds (α–DCs), fructosazine (FR) and deoxyfructosazine (DOFR), melanoidins, etc. Among the major α-DCs, 3-deoxyglucosone (3-DG), glucosone (G), methylglyoxal (MGO), glyoxal (GO) and diacetyl (DA) can be generated from GlcN at as low as 25 °C, while increasing the reaction temperature to 37 or 50 °C can speed up this degradation process. MGO, GO, DA, and 3-DG have been reported to have antibacterial activities. Apart from α-DCs, FR and DOFR are the self-condensation products of GlcN. The latter have been reported to have anti-inflammatory properties and are applied in therapeutic uses. At the same time, non-enzymatic browning reactions can generate potential toxic compounds, including 4-methylimidazole (4-MEI), 2-acetyl-4-tetrahydroxybutylimidazole (THI), and 5-hydroxymethylfurfural (5-HMF).
The first study aimed to examine the non-enzymatic browning of GlcN under UV-C radiation at 25 °C, referred as “cold caramelization”. Several UV-C exposure times were studied, including 0, 20, 60, 120 min at two GlcN concentrations of 15% and 30%. The physico-chemical properties, quantitation of α-DCs and polyhydroxylalkyl pyrazines (FR and DOFR), alkylimidazoles and 5-hydroxymethylfurfural were determined in all resulting GlcN caramels. The results revealed the possibility of generating GlcN caramel containing desirable compounds by applying UV-C. Specifically, longer UV-C exposure time produced caramel with higher content of G and 3-DG, as well as the GlcN self-condensation products, FR and DOFR. The amount of glucosone was significantly higher compared to GlcN caramels produced under heat treatment. Additionally, none of the neo-formed contaminants were detected during the process. Thus, UV-C treatment may be a newly advantageous method of producing GlcN caramel.
The second study focused on the effect of spray-drying on the non-enzymatic browning of GlcN incubated at 50 °C and 90 °C for 12 h. The resulting spray-dried GlcN caramel powders were analyzed along with the non-spray-dried GlcN caramel solutions to compare their physico-chemical properties and concentrations of polyhydroxylalkyl pyrazines, alkylimidazoles, and heterocyclic compounds. Spray-dried GlcN caramels were found to have lower concentrations of both non-volatile FR and DOFR, as well as THI and 5-HMF.
In summary, this thesis examined the non-enzymatic browning of GlcN under the application of UV-light and spray-drying, which revealed the possibilities of creating desirable caramels containing bioactive compounds. The resulted caramels can be potentially applied in different food applications.