Studies of human twins reveal genetic variation that affects dietary fat perception.

To learn more about the mechanisms of human dietary fat perception, 398 human twins rated fattiness and liking for six types of potato chips that differed in triglyceride content (2.5, 5, 10, and 15% corn oil); reliability estimates were obtained from a subset (n = 50) who did the task twice. Some chips also had a saturated long-chain fatty acid (hexadecanoic acid, 16:0) added (0.2%) to evaluate its effect on fattiness and liking. We computed the heritability of these measures and conducted a genome-wide association study (GWAS) to identify regions of the genome that co-segregate with fattiness and liking. Perceived fattiness and liking for the potato chips were reliable (r = 0.31-0.62, p < 0.05) and heritable (up to h2 = 0.29, p < 0.001, for liking). Adding hexadecanoic acid to the potato chips significantly increased ratings of fattiness but decreased liking. Twins with the G allele of rs263429 near GATA3-AS1 or the G allele of rs8103990 within ZNF729 reported more liking for potato chips than did twins with the other allele (multivariate GWAS, p < 1×10-5), with results reaching genome-wide suggestive but not significance criteria. Person-to-person variation in the perception and liking of dietary fat was (a) negatively affected by the addition of a saturated fatty acid and (b) related to inborn genetic variants. These data suggest liking for dietary fat is not due solely to fatty acid content and highlight new candidate genes and proteins within this sensory pathway.

Mixed 3-mono-O-alkyl cellulose: synthesis, structure characterization and thermal properties.

The 3-mono-O-alkyl cellulose samples bearing two different ether moieties, namely methyl/ethyl, methyl/n-propyl, and ethyl/n-propyl were synthesized applying protecting group technique. The NMR spectra of the peracetylated products revealed the regioselectivity of the alkylation as well as the degree of substitution of both alkyl moieties. The number average degree of polymerization (DPn) monitored by size exclusion chromatography decreases from DPn 117 (Avicel PH-101, starting material) to DPn 34 (sample 4f) due to the multi-step synthesis. It could be demonstrated that the lower critical solution temperature (LCST) is influenced by the degree of substitution of both alkyl groups. For example, LCST values between 33 and 58 °C were measured for aqueous solutions of 3-mono-O-ethyl/n-propyl cellulose. On the contrary, the thermal behavior of a physical mixture of 3-mono-O-ethyl- and 3-mono-O-n-propyl cellulose, e.g., was controlled by the derivative with the lowest LCST.

Influence of Ethanol on Emulsions Stabilized by Low Molecular Weight Surfactants.

The effect of ethanol on oil-in-water emulsions stabilized with low molecular weight surfactants was investigated. Oil-in-water emulsions were prepared containing varying percentages of ethanol and sunflower oil, and stabilized with different emulsifiers (Tween 20, Tween 80, and Lecithin). Droplet size, viscosity, density, and interfacial tension measurements were carried out. The droplet size of emulsions stabilized by each of the surfactants studied decreased with the addition of ethanol to the aqueous phase showing a minimum at a concentration of ethanol around 40%. The trend in droplet size is accompanied by a decrease in the interfacial tension between water and oil as the ethanol concentration increases. Viscosity measurements show that the change in viscosity of the final emulsion is the result of the change in viscosity of the continuous phase, as well as the change in solubility of the surfactants due to the addition of ethanol. The density of the continuous phase decreases with the addition of ethanol and it is possible to match the densities of the two phases in order to reduce the effect of creaming/sedimentation and improve stability. This study provides scientific evidence for the formulation of stable emulsions containing a range of ethanol form 0 to 40%. PRACTICAL APPLICATION: Formation and stability of food-grade emulsions in the presence of ethanol.

Self-association of novel mixed 3-mono-O-alkyl cellulose: Effect of the hydrophobic moieties ratio.

Heat-induced self-association of regioselectively functionalized 3-O-alkyl celluloses bearing both ethyl- and propyl groups dissolved in water was studied by means of differential scanning calorimetry and oscillatory shear rheology. The measured degrees of substitution were close to 1 but the ratio of ethyl (DSEt) to propyl groups (DSPr) was varied. The aggregation process is intimately coupled with phase separation as shown by the appearance of clouding in the same temperature range. Phase separation is arrested by the incipient gelation; whereby "stronger" gels are produced with high amounts of the propyl substituent than "weaker" phase separating samples as the amount of ethyl groups increases and the amount of propyl groups decreases. The correlation between rheology and thermal analysis clearly demonstrates that aggregation leads to formation of a gel network. It was found that as the ethyl moiety is replaced by propyl group the enthalpies of the thermal transitions increase strongly together with an increase of the elastic modulus (G') and the network is also more coherent with a steady decrease in tanδ (G″/G'). Reversibility was observed on cooling with a marked hysteresis for samples containing high levels of propyl groups. Hysteresis on cooling was explained in term of additional consolidation of the structure occurring at temperature much higher than the aggregation temperature, possibly involving backbone-backbone interactions. Quantitative analysis of the DSC data, based on the two-state thermodynamic model described by Armstrong et al. (1995) enabled evaluation of the van't Hoff enthalpy and the aggregation number. On the basis of those thermodynamic parameters, an "intermolecularly bridged clusters" model is proposed for the heat-induced transition of 3-O-ethyl-propyl cellulose ethers. The van't Hoff enthalpy/calorimetric enthalpy ratio ΔHvH/ΔHcal further indicates on the cooperativity of the process. The number of clusters and indeed the number of molecular chains comprising a cluster are both dependent upon the ratio of the two hydrophobic moieties. An increase in the aggregation number (n) (more aggregates coming together) occurs as ethyl is replaced by propyl, consistent with the observation of a "stronger" gel. The effect of the two different moieties on the physico-chemical properties of 3-O-ethyl-propyl cellulose ethers has been explained in term of different size/hydrophobicity of the two moieties and their distribution.