The neuronal encoding of oral fat by the coefficient of sliding friction in the cerebral cortex and amygdala

Fat in the diet contributes to the pleasant mouthfeel of many foods, but overconsumption may contribute to obesity. Here we analyze what properties of fat in the mouth are sensed, by analyzing the responses of neurons in the macaque insular taste cortex, and two areas to which it projects the orbitofrontal cortex where the pleasantness of fat is represented, and the amygdala. We discovered that the firing rate responses of these fat-responsive neurons are correlated with the coefficient of sliding friction (CSF) and not with viscosity which reflects food thickness. Other, not fat-sensitive, neurons encoded viscosity and not the CSF. Neuronal population analyses confirmed that fat-responsive neurons conveyed information about the CSF but not about viscosity. Conversely the viscosity-sensitive neuronal population conveyed information about viscosity but not about the CSF. This new understanding of the representation of oral fat in the cerebral cortex and amygdala opens the way for the systematic development of foods with the pleasant mouthfeel of fat, together with ideal nutritional content and has great potential to contribute to healthy eating and a healthy body weight

Encapsulation stability of duplex emulsions prepared with SPG cross-flow membrane, SPG rotating membrane and rotor-stator techniques—A comparison

AbstractFood grade duplex W1/O/W2 emulsions were prepared using three different techniques: SPG cross-flow membrane, SPG rotating membrane and high-shear mixer. The primary W1/O emulsion had sodium chloride encapsulated in the inner aqueous droplets as a marker compound. Duplex emulsion droplet size and salt encapsulation were both investigated by modifying the emulsification conditions inherent for each technique; cross-flow velocity (CFV) and trans-membrane pressure (TMP) for the cross-flow membrane, rotational velocity (RV) and TMP for the rotating membrane, and mixing time for the high-shear mixer.Emulsion droplet size was shown to increase with TMP and to decrease with both CFV and RV. Minimum droplet size obtained (∼12 μm) was similar for all three emulsifying techniques, which suggests that at high shear stresses, the minimum droplet size is determined primarily by the decrease in the interfacial tension.It was also shown that the amount of salt released during storage depends on the emulsification technique (8–20% for the cross-flow membrane, ∼13% for the high-shear mixer and ∼8% for the rotating membrane). The differences in salt release were explained in terms of emulsions droplet size and interfacial properties of adsorbed surfactant molecules. The unexpected high amount of salt released by duplex emulsions produced by the cross-flow membrane was associated with the magnitude and duration of shear forces, which act on duplex droplets during semi-batch emulsification