Effective Connectivity in the Human Brain for Sour Taste, Retronasal Smell, and Combined Flavour

Brain activation in older adults during odor identification is related to ApoE, t-tau/Aβ1-42, and hippocampal volume

Despite altered odor identification preceding and predicting Alzheimer's disease (AD) cognitive decline, an inadequate understanding of how AD pathology affects odor memory functions limits its use as a preclinical biomarker. Multivariate linear regression was applied to whole-brain blood-oxygen-level-dependent (BOLD) activations during odor identification task (OID) responses in older adults without dementia (N = 36, 44.4 % ε4 carriers, MAge= 76.61). Apolipoprotein-E ε4 allele status, cerebrospinal fluid levels of total-tau to Amyloid-β1-42, and MRI-derived hippocampal volume measures were used as predictors. The predictors described significant BOLD variation in regions that are associated with necessary OID functions and affected by AD neurodegeneration during OID responses; moreover, all predictors were associated with significant (P < .001) negative BOLD effects in essential task regions during at least one response condition. This evidence suggests significant pathological effects of AD biomarkers on OID-response neural activity in older adults without dementia and should motivate future combined-biomarker investigations of OID functions in preclinical populations.

Separation and characterization of sweet compounds in Baijiu by molecular distillation combined with molecular sensory science

Sweetness is a crucial taste component in Baijiu. However, comprehensive research on the sweetness of Baijiu remains limited, and traditional methods for flavor analysis are not well-suited for identifying the sweet compounds. To address this, a multi-stage molecular distillation method, combined with molecular sensory science, was developed to more effectively and scientifically analyze the key sweet compounds in Baijiu. The recovery rates of samples and compounds were 93.8 % ∼ 98.3 % and 81.6 % ∼ 118.3 %. 15 important compounds with a taste dilution factor (TD) value ≥64 were identified through gas chromatography-mass spectrometry (GC-MS) combined with taste dilution analysis (TDA). By calculating their taste activity values (TAV), 10 primary sweet compounds with TAV ≥1 were determined. Further taste recombination and omission experiments confirmed that ethyl hexanoate, ethyl heptanoate, ethyl octanoate, ethyl 2-methylbutyrate, 1-butanol, phenethyl alcohol, and ethyl acetate contribute significantly to Baijiu's sweetness and are identified as the key sweet compounds.

Association between olfactory dysfunction and gustatory dysfunction: evidence from the National Health and Nutrition Examination Survey

Background

Olfactory dysfunction (OD) and gustatory dysfunction (GD) are common among adults, with prevalence increasing significantly in older age groups. Both dysfunctions have negative effects on appetite, nutrition, social functioning and even environmental safety. OD and GD frequently coexist, indicating a possible close association between these conditions. At present, there is a lack of large-sample epidemiological studies on the relationship between OD and GD. Our study aims to investigate the relationship between OD and GD using both measurement and questionnaire data from the 2013-2014 NHANES for US adults aged 40 years and older.

Methods

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES). OD and GD were both assessed by measurements and questionnaires. The association between OD and GD was investigated with logistic regression models by adjusting for demographic characteristics, systemic diseases, and diseases of the nose and pharynx. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) are presented.

Results

Participants with complete olfactory and gustatory measurements and questionnaires (n = 2,582) were included. Using whole-mouth measurements, anosmia OD significantly increased the odds of hypogeusia and ageusia GD after adjusting for confounding factors. Similarly, the questionnaire data revealed that OD significantly increased the odds of GD. However, hyposmia OD decreased the odds of hypogeusia GD using the tongue-tip taste measurement.

Conclusion

Our findings highlighted that OD was closely associated with GD in a nationally representative sample of US adults.

Gustatory event-related potential alterations in olfactory dysfunction patients

The phenomenon that longstanding impaired olfactory function is associated with the decreased gustatory function was described in present studies, which was seems attributed to mutual chemosensory interactions. And the interaction between olfaction and gustation still needs more research to figure out. The objective of the study was to investigate how the taste was influenced by olfactory impairment in the central pathway. We tested 33 subjects with normal (n = 19) or impaired (n = 14) olfactory function for their gustatory event-related potentials (gERPs). Validated tests were used for olfactory and gustatory testing (Sniffin’ Sticks, gERPs, and three-drop test). This study reported an objective gustatory function decline in olfactory dysfunction participants. However, it also reported the increased gustatory event-related potentials of olfactory dysfunction participants, especially at the frontal electrode (F_Z) and electrode 16 (E16), and the reduced latency of P2 peak of them at electrode 21 (E21), while no obvious difference was observed at the centro-parietal electrode (P_Z). Inferior insula might be the main response area for the increase in gERPs, and this increase averaged amplitude of the P2 component may attribute to compensation of the secondary gustatory response that occurred in the gustatory processing of olfactory-impaired patients.