Abstract

Purpose - The objective of this article is to investigate the binding of several lactones to soya protein isolate and soya protein under different conditions and, particularly, the extent of binding of the lactones ?-9, ?-10, d-10 and d-11, in different concentrations as well as the effect of various parameters on their binding ability. Design/methodology/approach - Capillary column gas chromatography was used for the determination of lactones and the manual system was used for taking samples and for headspace analysis. Infrared spectroscopy was used for confirmation and investigation. Findings - The percentage of binding of lactones ?-9, ?-10, d-10, d-11 on the soya protein is almost the same (about 33-34 per cent). According to the Klotz equation, the bound ligand concentration was calculating as the number of moles of ligand bound per mole of protein. The results varied, but were similar. Specific experiments in water system with soya protein isolate (1 per cent) showed that the time taken for lactones ?-10 and d-11 to reach equilibrium, the factors of temperature and pH affected the percentage of lactone bound. Research limitations/implications - The amount of added lactone in products containing soya protein isolate should be investigated by using panel tests to confirm the improvement of flavour. Practical implications - Flavour binding of lactones can be used to provide some foods with the required flavour impression by adding lactones to a bland soy protein base. Originality/value - The flavour binding of lactones, which was investigated in the present paper, has not been adequately investigated in previous scientific research and the effects of the factors that influence their binding are very important.