UBC Theses and Dissertations
Elucidation of the interaction between soy protein isolate and simulated beef flavour Moon, Soo Yeun
The objective of this research was to explore interactions between aroma compounds in simulated beef flavour (SBF) and soy protein isolate (SPI) that may be involved in the suppression of beefy notes in SBF by SPI. A sensitive and reproducible headspace solid phase microextraction (HSSPME) was established to isolate volatile compounds in SBF for analysis by gas chromatography (GC). Volatile and odour-active compounds in SBF were qualitatively evaluated by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) using detection frequency method, respectively. A total of 70 compounds were tentatively identified including three furans, six S-heterocyclic compounds, ten N-heterocyclic compounds, six aldehydes, three alcohols, and two esters. Of 49 volatile compounds detected in the sniffing port of GC-O, the most odour-active included 2-methyl-3-furanthiol, delta-3-carene, alphaterpinene, 2-ethyl-3,6-dimethylpyrazine, and several unidentified odourants. Descriptive analysis (DA) along with GC analysis was conducted to investigate changes in SBF aroma characteristics upon addition of SPI. Five attributes (beefy, roasted, yeasty, soymilk-like and cereal) were selected to assess various mixtures of SBF and SPI. The results from DA confirmed that "roasted", "beefy" and "yeasty" notes were highly positively correlated with SBF concentration, and the beefy related notes were substantially suppressed by increasing SPI content. Fifteen peaks from GC analysis were selected as indicator peaks to represent beef attribute in the mixtures of SPI and SBF. Changes in the release of beefy aroma components of SBF by addition of ingredients (glucosamine, sucrose, ascorbic acid, and/or polyethylene glycol) to SPI and the changes in SPI protein structure induced by the ingredients were investigated. The reduction of disulfide bonds, increased surface hydrophobicity and increased unordered structure in SPI containing ascorbic acid alone or with polyethylene glycol, along with increased GC peak areas of indicator peaks in those SPI-SBF mixtures, were found to be associated with an increase in the perceived beef characteristic attributes in descriptive analysis. These results provide the basis for further research to elucidate strategies maximizing perception of beefy aroma in soy based products.