Investigation of human flavor perception and discrimination of the fat content in food using DR A-Not A and 3-AFC methods

Characterization of perceptual interactions among aroma compounds found in Rose damascena and Angelica dahurica root essential oil with threshold, S-curve, σ-τ plot and molecular docking

The study investigated the perceptual interaction between two types of Rose damascena essential oil and two types of Angelica dahurica root essential oil. Using gas chromatography-olfactometer (GC-O) and gas chromatography-mass spectrometer (GC-MS), 24 and 25 aromatic compounds in Rose damascena essential oil and Angelica dahurica root essential oil were identified and quantified, respectively. Based on flavor dilution (FD) values and odor activity values (OAVs), 10 important aroma compounds in Rose damascena essential oil and 6 in Angelica dahurica root essential oil were identified. The perceptual interactions between these aroma compounds were explored by using the threshold method, S-curve, and σ-τ plot. Additionally, molecular docking analysis revealed changes in binding energy and binding sites. Notably, when aroma compounds shared similar structures and fragrances, they exhibited additive or synergistic effects. Conversely, dissimilar compounds showed different interactions. The molecular docking results aligned with our experimental findings. Overall, our study demonstrates that the threshold method, S-curve, σ-τ plot, and molecular docking enhance our understanding of aroma compound perceptual interactions between Rose damascena essential oil and Angelica dahurica root essential oil. These insights provide a theoretical foundation and practical guidance for improving the aroma of Angelica dahurica root essential oil and studying perceptual interactions among essential oils.

Exploring the neural correlates of fat taste perception and discrimination: Insights from electroencephalogram analysis

Understanding neural pathways and cognitive processes involved in the transformation of dietary fats into sensory experiences has profound implications for nutritional well-being. This study presents an efficient approach to comprehending the neural perception of fat taste using electroencephalogram (EEG). Through the examination of neural responses to different types of fatty acids (FAs) in 45 participants, we discerned distinct neural activation patterns associated with saturated versus unsaturated fatty acids. The spectrum analysis of averaged EEG signals revealed notable variations in δ and α-frequency bands across FA types. The topographical distribution and source localization results suggested that the brain encodes fat taste with specific activation timings in primary and secondary gustatory cortices. Saturated FAs elicited higher activation in cortical associated with emotion and reward processing. This electrophysiological evidence enhances our understanding of fundamental mechanisms behind fat perception, which is helpful for guiding strategies to manage hedonic eating and promote balanced fat consumption.

Oral/taste sensitivity to non-esterified long-chain fatty acids with varying degrees of unsaturation

Understanding human oral/taste sensitivity to long-chain non-esterified fatty acids (NEFA) with varying physicochemical properties is essential to reducing the intake of fats and altering the intake composition. This study investigated the differences in human taste sensitivity to two NEFA: oleic acid and linoleic acid. Twenty-four female subjects were divided into two equal sensitivity groups, and they performed discrimination tests for both fatty acids against bottled water using either the triangle or the DR A-Not A test. To achieve an accurate measurement of NEFA sensitivity, the stimulus was carefully prepared, avoiding additives that could interfere with the binding of fatty acids to receptors. Stimuli concentrations were selected to be within the lowest range (9.9 to 177.3 μM) evaluated in previous research. Through a systematic stimulus control process, this study confirmed that greater sensitivity was exhibited to linoleic acid than oleic acid, resulting in better discrimination than previous studies.

Variability of oral/taste sensitivity to fat: An investigation of attribution from detection threshold methods with repeated measurements

Accumulating psychophysical evidence suggests substantial individual variability in oral/taste sensitivity to non-esterified, long-chain fatty acids (NEFA), which is commonly referred to as fat taste or oleogustus. Recent studies have sought to determine its associations with human factors such as body mass index (BMI) and food preferences, as it has been claimed that excessive fat consumption is related to several health conditions, including obesity. Yet, the findings are controversial. On the other hand, it has been noted that considerable variability also occurs based on the methodology used to measure the fatty acid taste. Specifically, learning effects have been observed over repeated measurements of the detection threshold of NEFA, yet there has been no methodology available to take into account these learning effects. Accordingly, in the present study, a novel methodology using a descending-block dual reminder A-Not A (DR A-Not A) method with a warm-up has been proposed to measure the NEFA detection threshold based on the signal detection theory and considering NEFA taste learning effects over repeated sessions. Homogeneous subjects (young adult Korean females within the normal BMI range, non-vegetarians) were randomized to either the novel descending-block DR A-Not A method or ascending triangle method that is commonly used for fat perception studies. Pure oleic acid emulsions were used as fat taste stimuli to be discriminated from pure mineral water. Each subject completed 14 repeated visits. For the ascending triangle method, 14 thresholds were determined using a stopping rule, while for the novel method, 7 thresholds were determined each per two consecutive days, using a criterion of a lower limit of 50% confidence interval of d' = 0.5, considering the practical aspects of taste studies in food sensory science. Based on the group median results of the last two visits, the variability of the detection thresholds was reduced using the novel descending-block DR A-Not A method due to better learning effects over repeated sessions. This shows the potential of the descending-block DR A-Not A threshold method for further studies on oral/taste sensitivity to fat.