Olive oil aroma extract modulates cerebral blood flow in gustatory brain areas in humans.

BACKGROUND: Low- and high-fat meals affect homeostatic and gustatory brain areas differentially. In a previous study, we showed that a high-fat meal decreased cerebral blood flow (CBF) in homeostatic brain areas (hypothalamus), whereas a low-fat meal increased CBF in gustatory regions (anterior insula). OBJECTIVE: The aim of this study was to investigate the long-lasting effect of fat-free flavor-active compounds of olive oil on the brain and whether those aroma components can trigger fat-associated brain responses in homeostatic and gustatory regions. DESIGN: Eleven healthy male subjects participated in a functional magnetic resonance imaging study. On 2 measurement days, subjects consumed single-blinded a plain low-fat yogurt or low-fat yogurt mixed with a fat-free aroma extract of olive oil. Resting CBF was measured before and 30 and 120 min after yogurt intake. Hunger was rated before each measurement. Blood samples were collected at 6 time points. RESULTS: The extract-containing yogurt elicited higher CBF in the frontal operculum 30 and 120 min after a meal. Furthermore, the activity change in the anterior insula after 30 min correlated positively with the glucose change in the extract condition only. No effects were observed in the hypothalamus. CONCLUSIONS: The anterior insula and the frontal operculum are regarded as the primary taste cortex. Modulation of the frontal operculum by the yogurt containing the olive oil extract suggests that it might be possible to simulate fat-triggered sensations in the brain on the gustatory level, possibly by ingredients the body implicitly associates with fat. This trial was registered at clinicaltrials.gov as NCT01716286.

Relating creamy perception of whey protein enriched yogurt systems to instrumental data by means of multivariate data analysis.

UNLABELLED: Yogurts differing in fat content, protein content, and casein to whey protein ratio were produced, and structurally as well as sensorially examined. The objective of the current research was to evaluate the predictive value of rheological and particle size measurements concerning sensory appearance and texture attributes in 13 differently composed stirred yogurt systems, with a focus on graininess, viscosity, and creaminess. Structural and sensory analyses showed large differences in texture properties between the tested yogurt systems. Both data sets were correlated by means of multivariate statistical methods. Sensory graininess was highly correlated with particle size-related parameters, sensory viscosity was highly correlated with destructive rheological parameters, and creamy perception was highly correlated with particle size-related parameters and destructive rheological parameters but was not as well described by any oscillatory parameter. Best predictive ability (r(2) > 0.89) was found for creaminess combining particle size related- and destructive rheological parameters tested within this study. PRACTICAL APPLICATION: Knowing the instrumental parameters describing sensory textural attributes provides important information for having a better understanding of the underlying processes during consumer's perception. Knowledge about the sensory behavior of a product and its oral processing imparts an opportunity to fasten the product development process. By means of yogurt systems instrumental parameters derived from particle size analysis and rheological measurements were correlated with sensory attributes in order to determine the main factors leading to the mouthfeel sensations grainy, viscous, and creamy of semisolid milk products.

Fat intake modulates cerebral blood flow in homeostatic and gustatory brain areas in humans.

BACKGROUND: The hypothalamus is the central homeostatic control region of the brain and, therefore, highly influenced by nutrients such as glucose and fat. Immediate and prolonged homeostatic effects of glucose ingestion have been well characterized. However, studies that used stimulation with fat have mainly investigated immediate perceptional processes. Besides homeostatic processes, the gustatory cortex, including parts of the insular cortex, is crucial for the processing of food items. OBJECTIVE: The aim of this study was to investigate the effect of high- compared with low-fat meals on the hypothalamus and the insular cortex. DESIGN: Eleven healthy men participated in a single-blinded, functional MRI study of high- and low-fat meals on 2 measurement days. Cerebral blood flow (CBF) was measured before and 30 and 120 min after intake of high- and low-fat yogurts. Hunger was rated and blood samples were taken before each CBF measurement. RESULTS: High-fat yogurt induced a pronounced decrease in CBF in the hypothalamus, and the corresponding CBF change correlated positively with the insulin change. Furthermore, insular activity increased after 120 min in the low-fat condition only. The CBF change in both regions correlated positively in the high-fat condition. CONCLUSIONS: The decrease in hypothalamic activity and the interaction with the insular cortex elicited by fat may contribute to an efficient energy homeostasis. Therefore, fat might be a modulator of homeostatic and gustatory brain regions and their interaction. This trial was registered at clinicaltrials.gov as NCT01516021.

Deposition of pectin/poly-L-lysine multilayers with pectins of varying degrees of esterification.

The effect of pectin esterification on the assembly of multilayers consisting of poly-L-lysine (PLL) and pectin was studied using surface plasmon resonance (SPR), Fourier transform infrared-attenuated total reflection spectroscopy (FTIR-ATR), and a quartz crystal microbalance with dissipation monitoring (QCMD). With each layer deposited, there was a progressive increase in mass. The net charge of the multilayers was positive and increased with increasing degree of esterification of the pectin. Multilayer fabrication involved a limited fractionation of the pectin preparations, with the more highly esterified pectins having a weaker affinity for PLL. The multilayers were relatively hydrated structures with estimates of solids content in the range 10-32% w/w. The more highly esterified pectins had a tendency to form more hydrated structures, which showed a strong deswelling when PLL was added to a freshly deposited pectin layer.