The relationships between common measurements of taste function

BACKGROUND: There are five common, independent measures used to characterize taste function in humans: detection and recognition thresholds (DT and RT), suprathreshold intensity ratings of prototypical tastants, propylthiouracil (PROP) bitterness intensity, and fungiform papillae (FP) number. METHODS: We employed all five methods to assess taste function of 65 women (21.5 ± 4 years, BMI 22.3 ± 2.8 kg/m(2)). Pearson correlation coefficients were calculated between the different measures. RESULTS: The DT and RT were positively correlated for sweet, bitter, sour, and umami (p < 0.05), but not for salt. The DT or RT did not correlate with suprathreshold intensity ratings, except for umami (suprathreshold intensity and RT: r = -0.32, p = 0.009). FP number did not correlate with any measurement of taste function. PROP bitterness intensity ratings did not correlate with any measurement of taste function, except for suprathreshold ratings for saltiness (r = 0.26, p = 0.033). CONCLUSION: As most of the individual measures of taste function did not correlate with each other, with exception of the two threshold measures, we conclude that there are multiple perceptual phases of taste, with no single measure able to represent the sense of taste globally.

A computational search for lipases that can preferentially hydrolyze long-chain omega-3 fatty acids from fish oil triacylglycerols

Consumption of long-chain omega-3 fatty acids is known to decrease the risk of major cardiovascular events. Lipases, a class of triacylglycerol hydrolases, have been extensively tested to concentrate omega-3 fatty acids from fish oils, under mild enzymatic conditions. However, no lipases with preference for omega-3 fatty acids selectivity have yet been discovered or developed. In this study we performed an exhaustive computational study of substrate-lipase interactions by docking, both covalent and non-covalent, for 38 lipases with a large number of structured triacylglycerols containing omega-3 fatty acids. We identified some lipases that have potential to preferentially hydrolyze omega-3 fatty acids from structured triacylglycerols. However omega-3 fatty acid preferences were found to be modest. Our study provides an explanation for absence of reports of lipases with omega-3 fatty acid hydrolyzing ability and suggests methods for developing these selective lipases.

Development of a resin based silica monolithic column encapsulation

As monolithic columns become more extensively used in separation based applications due to their good flow and high surface characteristics, there has arisen the need to establish simple, reliable fabrication methods for fluidic coupling and sealing. In particular, the problem of liquid tracking between a monolith's outer surface and the sealing wall, resulting in poor flow-through performance, needs to be addressed. This paper describes a novel resin-based encapsulation method that penetrates 0.3 mm into the outer surface of a 4 mm diameter monolith, removing the so-called wall-effect. Results based on the peak analysis from 1 μL of 0.4% thiourea injected into a 98:2 water:methanol mobile phase flowing at 1 mL min^-1 indicate excellent flow conservation through the monolith. A comparison of peak shape and height equivalent to a theoretical plate (HETP) data between the reported resin-based method and the previously reported heat shrink tubing encapsulation methodology, for the same batch of monoliths, suggests the resin based method offers far superior flow characteristics. In addition to the improved flow properties, the resin casting method enables standard polyether ether ketone (PEEK) fittings to be moulded and subsequently unscrewed from the device offering simple reliable fluidic coupling to be achieved.

Complex coacervation between flaxseed protein isolate and flaxseed gum

Flaxseed protein isolate (FPI) and flaxseed gum (FG) were extracted, and the electrostatic complexation between these two biopolymers was studied as a function of pH and FPI-to-FG ratio using turbidimetric and electrophoretic mobility (zeta potential) tests. The zeta potential values of FPI, FG, and their mixtures at the FPI-to-FG ratios of 1:1, 3:1, 5:1, 10:1, 15:1 were measured over a pH range 8.0-1.5. The alteration of the secondary structure of FPI as a function of pH was studied using circular dichroism. The proportion of a-helical structure decreased, whereas both &beta;-sheet structure and random coil structure increased with the lowering of pH from 8.0 to 3.0. The acidic pH affected the secondary structure of FPI and the unfolding of helix conformation facilitated the complexation of FPI with FG. The optimum FPI-to-FG ratio for complex coacervation was found to be 3:1. The critical pH values associated with the formation of soluble (pHc) and insoluble (pH<inf>&Phi;1</inf>) complexes at the optimum FPI-to-FG ratio were found to be 6.0 and 4.5, respectively. The optimum pH (pH<inf>opt</inf>) for the optimum complex coacervation was 3.1. The instability and dissolution of FPI-FG complex coacervates started (pH&Phi;<inf>2</inf>) at pH2.1. These findings contribute to the development of FPI-FG complex coacervates as delivery vehicles for unstable albeit valuable nutrients such as omega-3 fatty acids.