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Effect of Thermal Treatment on Chemical Structure of Β-Lactoglobulin and Basil Seed Gum Mixture at Different States by ATR-FTIR Spectroscopy

Rafe, Ali, Razavi, Seyed M.A.
International journal of food properties 2015 v.18 no.12 pp. 2652-2664
Fourier transform infrared spectroscopy, basil, beta-lactoglobulin, chemical structure, emulsifying properties, gelation, gels, heat, heat treatment, hydrogen bonding, polymers, salts, uronic acids
Attenuated total reflection Fourier transform infrared spectroscopy was used to compare the structure of β-lactoglobulin, basil seed gum, and β-lactoglobulin-basil seed gum mixtures, at different states (powder, solution, and gel). The effects of heating and different ratios of β-lactoglobulin-basil seed gum were also investigated to determine their impact on chemical structure and understand their interaction. The results showed that gelification process proved a pronounced effect upon β-lactoglobulin secondary structure, leading to the formation of intermolecular hydrogen-bonding β-sheet structure. These results confirmed that this structure may be necessary for the formation of a gel network. Basil seed gum had a distinct peak at around 1603 cm –¹ that relates to –COO –¹ stretching of carboxylate salts, probably uronic acids, which approved its anionic structure. The Fourier transform infrared spectroscopy findings strongly suggested that these two polymers are thermodynamic incompatible as amide I peak was increased in the β-lactoglobulin-basil seed gum mixed system and carbon–nitrogen (CN) stretching peak was observed at 2125 cm –¹. On the basis of these findings, it was possible to modify the ability of β-lactoglobulin-basil seed gum to form a gel and as a consequence to control the gelling and emulsifying properties.