The contribution of subliminal perceptions, dietary habits, and psychological traits to the perception of oral tingling and burning sensations.

The tingling evoked by Sichuan pepper and the burning elicited by chili pepper constitutes the typical flavor of Sichuan cuisine and is a component of leisure food. Although factors affecting the burning sensation have extensively been studied, few studies have examined the factors of individual sensitivity, personality traits, and dietary habits that contribute to the perception of oral tingling sensation, which hinders the formulation of tingling products and the development of new products. In contrast, many studies have examined the factors influencing the burning sensation. In this web-based survey, 68 participants disclosed their dietary habits, liking for tingling and hot foods, and psychological traits. Individual sensitivity to the tingling and burning sensation produced by a range of Sichuan pepper oleoresin and capsaicin solutions was determined using rated differences from control, generalized labeled magnitude scale method and ranking test. The consistency score indicated the accuracy of individual ranking results while also providing an indirect response to the sensitivity of the participant to supra-threshold for burning or tingling. Individual ratings for medium Sichuan pepper oleoresin concentrations significantly correlated with the just noticeable difference (p < 0.01), and ratings for medium and high capsaicin concentrations correlated significantly with 6-n-propylthiouracil ratings (p < 0.01). Notably, the power exponent of burning was significantly correlated with the burning recognition threshold (p < 0.01), and the power exponent of tingling and burning were significantly correlated (r = 0.340, p < 0.05). There was a negative correlation between supra-threshold tingling and burning sensation perceptions and life satisfaction ratings. Further, intensity ratings for oral tingling and burning sensation did not always correspond with individual sensitivity indicators (e.g., recognition threshold, 6-n-propylthiouracil, just noticeable difference, and consistency score). Thus, this study provides new insight into establishing a sensory selection method for chemesthetic sensation panelists and theoretical guidelines for formulation design and in-depth analysis of popular tingling dishes and foods.

The influence of NaCl on the dynamic perception of the pungency sensation elicited by Sichuan pepper oleoresins.

A cross-modal interaction may exist between the perception of saltiness and the pungency elicited by Sichuan pepper oleoresin (Spo). Thirty-one hypersensitive panelists were selected to participate in this study. Spo solutions dissolved in different NaCl concentrations, ranging from 1.25 g/L to 167.9 g/L, were used as the test samples. The rated difference from control, the generalized labeled magnitude scale (gLMS), and the time-intensity (TI) method were used to determine the detection threshold (DT), the recognition threshold (RT), the intensity, and the dynamic perception of pungent sensation. The results revealed that the pungency thresholds increased significantly (p < 0.01) in the solution with a high NaCl (167.9 g/L) concentration. Furthermore, high NaCl solutions suppressed the pungency intensity at all Spo concentrations except for 0.02 g Spo/L in water (p < 0.05). The TI and principal component analysis (PCA) results showed that an increase in the Spo concentration prolonged the duration of the pungency sensation. However, the maximum intensity, the time to reach maximum intensity, the decay time of perception, and the end time of perception of the Spo solutions ranging from 2.13 g/L to 4.69 g/L were significantly reduced at medium (42.95 g/L) and high NaCl concentrations. Since the salty and pungency sensations exhibited by NaCl and Spo are common flavor combinations in food products and dishes, studying the influence of saltiness on the dynamic perception of pungent sensation not only aids the development of oral cleaners during pungency evaluation but also presents significant theoretical and practical value in creating pungent food and cuisine based on consumer preferences.

The enhancement of the perception of saltiness by Sichuan pepper oleoresin in a NaCl model solution.

Health concerns related to the intake of salt have necessitated the investigation into NaCl reduction by examining the cross-modal interaction between the perception of saltiness and pungency elicited by Sichuan pepper oleoresin (Spo). The category scale and the generalized Labeled Magnitude Scale (gLMS) were used to determine the degree to which Spo enhanced the perception of saltiness in the NaCl model solution. Sixty-eight participants were divided into the hyposensitive, semi-sensitive, and hypersensitive groups according to individual exponent. The power functions of saltiness under different pungency carriers were obtained. The level of enhancement varied between the different sensitivity groups and pungency carriers. In the hypersensitive group, the low and strong pungency carriers effectively enhanced the perception of saltiness at low to moderate, and moderate to strong NaCl solutions, respectively. In the semi-sensitive group, low and moderate pungency carriers induced additive effect in the perception of saltiness at full and moderately strong NaCl solutions, respectively. However, the additive effect was inadequate in the hypo-sensitive group. Therefore, the low pungency solution was more feasible for enhancing in the perception of saltiness, while the maximum NaCl reduction percentages corresponded to the hypersensitive and semi-sensitive groups at 38.61% and 39.06%, respectively. This research not only provided insight into the effect of pungency on the perception of saltiness as it related to individual sensitivity, but also presented valuable information regarding flavor when developing food with reduced salt content.

The relationship between alkylamide compound content and pungency intensity of Zanthoxylum bungeanum based on sensory evaluation and ultra-performance liquid chromatography-mass spectrometry/ mass spectrometry (UPLC-MS/MS) analysis.

BACKGROUND: Zanthoxylum bungeanum originating in different places varies in alkylamide content and pungency intensity. RESULTS: The pungency intensity of 19 Zanthoxylum bungeanum samples was first determined with Scoville pungency units (SPUs). The SPUs were found to range from 3.80E + 04 to 5.40E + 05. The chemical compositions and contents were measured next, using the ultra-performance liquid chromatography-mass spectrometry/ mass spectrometry (UPLC-MS/MS) method. The total alkylamide content ranged from 9.83 ± 0.15 to 89.98 ± 1.35 g kg-1 . Hydroxy-ϵ-sanshool, hydroxy-α-sanshool, hydroxy-ß-sanshool, hydroxy-γ-sanshool, bungeanool, and isobungeanool were found to be the key pungent compounds, ranging in proportion from 92.65% to 97.69%. The relationship between alkymide compound content and pungency intensity was also analyzed by ridge regression, and it was found that the ß values of independent variables were stable when k was more than 0.6. The regression coefficients of hydroxy-ϵ-sanshool, hydroxy-α-sanshool, hydroxy-ß-sanshool, hydroxy-γ-sanshool, bungeanool, isobungeanool, and other alkylamides were 0.105, 0.177, 0.386, -0.166, -0.006, 0.005, and -0.018, respectively. CONCLUSION: Hydroxy- sanshool compounds were important in determinant the pungency intensity of Z. bungeanum. Knowledge of the relationship between alkymide compound content and pungency intensity will assist in the creation of new methods to determine pungency intensity and provide a scientific basis for flavor design, development of pungent food products, and consumer choice evaluations. © 2018 Society of Chemical Industry.

[Analysis of NIR characteristic wavelengths for apple flesh firmness based on GA and iPLS].

In the present study, the fruit flesh firmness of apple was analyzed by near infrared (NIR) spectroscopy using an FT-NIR spectrometer. The sensitive spectral regions that provide the lowest prediction error were analyzed by different well-known variable selection methods, including dynamic backward interval partial least-squares (dynamic biPLS), sequential application of backward interval partial least-squares and genetic algorithm(dynamic biPLS & GA-PLS), and iterative genetic algorithm partial least-squares (iterative GA-PLS). Iterative GA-PLS, dynamic biPLS & GA-PLS led to a distinct reduction in the number of spectral data points with better predictive quality. Furthermore, the majority of selected wavelengths were content with the characteristic of the sorption bands of fruit flesh firmness. Pectin constituents, complex non-starch polysaccharides, which are related to texture change in apple, play an important role in their harvest maturity, ripening and storage. Comparing NIR characteristic wavelengths of apple flesh firmness and typical absorption bands for pectin, it was found that characteristic wavelengths of apple flesh firmness were consistent with the pectins relevant spectral regions. Therefore, the NIR characteristic wavelengths of apple firmness based on GA and iPLS reflected the chemical component of apple and the results were reasonable.

[Using GA-dOSC method to eliminate interference of peel with prediction of apple firmness based on near infrared diffuse reflection spectra].

In the present work, "Fuji" apples from Shandong Yantai were used to take the diffuse reflection spectra by FT-NIR PLS components (i.e., factors) were computed by nonlinear iterative partial least squares (NIPALS) and the number of latent factors (LV) was optimized by a leave-one-out cross-validation procedure on the calibration set. On the basis of partial least square (PLS) regression, the models for apples' firmness before and after peeling were compared. In order to eliminate the effect of apple peel on prediction, spectral pretreatments such as multiplicative scatter correction (MSC), derivative, direct orthogonal signal correction (DOSC) and wavelengths selection based on genetic algorithms (GA) were used. Finally, the results of different spectral treatments were compared. In conclusion, the RSDp of models for apples before and after peeling was 16.71% and 12.36%, respectively, suggesting that the apple peel played a negative role in constructing good predictive models. Moreover, the traditional spectral pretreatments (such as MSC, derivative) can hardly resolve the problem. In this research, GA-DOSC played an important role in reducing the interference of apple peel. It not only reduced the wavelength variables from 1480 to 36, but also reduced the latent variables from 5 to 1. The correlation coefficient (r) was improved from 0.753 to 0.805, and the RMSECV and RMESP were reduced from 1.019 kgf x cm(-2) and 1.197 kgf x cm(-2) to 0.919 kgf x cm(-2) and 0.924 kgf x cm(-2), respectively. Especially, the RSDp was decreased remarkably from 16.71% to 12.89%. The performance of the model after GA-DOSC treatment was similar to the model using spectra of apple flesh (12.36%). It was concluded that the prediction precision based on GA-DOSC satisfied the requirement of NIR non-destruction determination of apples firmness.

[Improving apple fruit quality predictions by effective correction of Vis-NIR laser diffuse reflecting images].

In the present study, improved laser-induced light backscattering imaging was studied regarding its potential for analyzing apple SSC and fruit flesh firmness. Images of the diffuse reflection of light on the fruit surface were obtained from Fuji apples using laser diodes emitting at five wavelength bands (680, 780, 880, 940 and 980 nm). Image processing algorithms were tested to correct for dissimilar equator and shape of fruit, and partial least squares (PLS) regression analysis was applied to calibrate on the fruit quality parameter. In comparison to the calibration based on corrected frequency with the models built by raw data, the former improved r from 0. 78 to 0.80 and from 0.87 to 0.89 for predicting SSC and firmness, respectively. Comparing models based on mean value of intensities with results obtained by frequency of intensities, the latter gave higher performance for predicting Fuji SSC and firmness. Comparing calibration for predicting SSC based on the corrected frequency of intensities and the results obtained from raw data set, the former improved root mean of standard error of prediction (RMSEP) from 1.28 degrees to 0.84 degrees Brix. On the other hand, in comparison to models for analyzing flesh firmness built by means of corrected frequency of intensities with the calibrations based on raw data, the former gave the improvement in RMSEP from 8.23 to 6.17 N x cm(-2).