Determination of Recognition Threshold and Just Noticeable Difference in the Sensory Perception of Pungency of Zanthoxylum bangeanum

Zanthoxylum bungeanum, also called the Szechuan pepper, is a pungent-flavored spice. Together with the chili pepper, it constitutes the typical flavor of famous Chinese Szechuan cuisine. With the worldwide popularity of Sichuan cuisine and pungent food, the research on sensory perception of pungency of Z. bungeanum becomes more important and necessary. This article first determined the sensory recognition threshold and just noticeable difference of pungency of Z. bungeanum. The pungent extract, containing hydroxyl α-sanshool (63.6%), hydroxyl β-sanshool (22.8%), and hydroxyl γ-sanshool (7.4%) from Z. bungeanum was used as the tested sample prepared in ethanol–water solution. Ten selected assessors participated in three sessions of sensory tests in standard sensory evaluation booths established according to ISO 8589 by following two-alternative forced choice procedure. The data showed that the recognition threshold was 0.036 mg pungent extract per 1 mL ethanol–water solution and just noticeable difference exponentially increased with the increase of the concentration of pungent extract solution. The response of pungency among assessors followed Weber’s Law with a stable Weber fraction (0.118) from 0.0360 to 0.500 mg pungent extract per 1 mL. Nevertheless, the fraction changed when the concentration of pungent extract solution was above 0.500 mg per 1 mL.     

Individual variation in fungiform papillae density with different sizes and relevant associations with responsiveness to oral stimuli

The association of fungiform papillae (FP) density with responsiveness to oral sensations is controversial. It has been speculated that FP size is a relevant feature for oral responsiveness, thus partially accounting for inconsistencies between FP density and oral responsiveness. This study aims to evaluate factors affecting the number of FP with different diameter sizes (age, gender, PROP status) and to explore the relevant associations with responsiveness to oral sensations in water solutions and food products.Three-hundred-fifty subjects participating in the Italian Taste project were involved, balanced for gender (53% females) and age class (18–30, 35%; 31–45, 35%; 46–60, 30%). The automated image analysis of tongue pictures was used to detect FP and count their frequencies, distinguishing 11 diameter size classes (range from 0.3 to 1.05 mm). Frequencies were converted into FP densities (FP/cm²) for each size. Taste responsiveness in water solutions (sour, bitter, salty, umami, sweet, astringent, pungent) and in three food products with varied intensity of target sensations (pear juice for sourness; bean purée for saltiness; tomato juice for pungency) was measured.Density of FP from all size classes decreased with age. Females showed higher FP density in size of 0.78–0.84 mm diameter, and males in the size of 0.44–0.49 mm. PROP status did not significantly affect the density of FP in any size class. Principal Component Analysis on individual FP density values of the 11 classes allowed identifying four subject groups with different FP patterns: high density and large diameter (HighLarge), high density and small diameter (HighSmall), low density and large diameter (LowLarge), low density and small diameter (LowSmall). FP pattern groups significantly affected oral responsiveness, the highest responsiveness was associated to the uniform pattern characterized by low density and small size FP.     

Encapsulated sodium supplementation of 4 weeks does not alter salt taste preferences in a controlled low sodium and low potassium diet

Preference for saltiness is learned by oral exposure to salt taste; however, some data suggest a role for bodily sodium and potassium levels on salt taste preferences as well. The objective was to investigate whether encapsulated sodium and potassium supplementation lead to altered salt taste responses among adults with high blood pressure on a low sodium and low potassium diet. Twenty-six participants with untreated upper-range prehypertension or stage 1 hypertension were on a fully controlled low sodium and low potassium diet (both targeted at 2 g/day) for 13 weeks. Participants received capsules with sodium (3 g/d), potassium (3 g/d), or placebo, for 4 weeks each, in randomized order in a double blind crossover design. Sensory evaluation was done before and after each supplementation period and involved ratings of pleasantness and intensity in different salt (NaCl) concentrations in food and water, desire-to-eat salty food, and detection threshold for NaCl. Neither sodium supplementation nor potassium supplementation led to alterations in salt taste responses in food and water, and did not affect detection threshold (P = 0.59). There was no clear role for sodium or potassium supplementation on desire-to-eat salty food. In addition, we did not find effects of reduced oral exposure to salt over weeks, through the sodium-reduced diet, on salt taste preferences, in contrast to earlier studies. In conclusion, the results of this study suggest preference for saltiness is independent of changes in bodily sodium or potassium levels.     

The associations between genetics,salt taste perception and salt intake in young adults

Food liking is one of the main determinants of food intake. Salt taste perception and preference, that play a role in liking of salt, may be genetically determined, although research in humans is scarce. The aim of this study was to explore the associations between genetics, salt taste perception, preference, self-reported salt habit and intake. The participants were young (18–35 years) and healthy adults (32 males and 63 females). Salt taste thresholds were determined with British Standard ISO3972:2011 methodology and salt taste preference by ratings of saltiness and pleasantness of tomato soup with salt concentrations reflecting salt content in foods. Self-reported salt habit was determined by asking participants how salty they usually eat their food and salt intake with two 24-hour 5-step multiple pass recalls. Genotyping for variants in the SCNN1B rs239345 and TRPV1 rs8065080 was performed. Participants homozygous for the minor allele of the rs8065080 had lower ratings of saltiness (p = 0.008) and higher ratings of pleasantness of soup (p = 0.027) when compared to major allele carriers. Preference for salt in soup was associated with salt habit (p = 0.003) and participants with high salt preference had higher salt intake compared to those with low salt preference (2236 ± 261 vs. 1543 ± 107 mg/1000 kcal, p = 0.017). TRPV1 rs8065080 may play a role in salt taste perception and preference, which should be confirmed in a larger sample size study. Hedonic appeal of salty food should be considered when providing personalised advice to change this behaviour.     

Relationship of pungency and leading flavour attributes in model food matrices – temporal aspects

Temporal aspects and interaction effect of pungency evoked by capsaicin/chili and leading flavour attributes in model food matrices were studied. Two experiments were performed: in experiment I pure capsaicin at three levels (0.5, 25, 125 ppm) was added to various carriers (water solution, potato starch gruel and tomato soup and sauce) and in experiment II chili powder was used as irritant (0.03%, 0.08%, 0.2%) in six different model food matrices (tomato, chicken and mushroom soups and sauces). Intensity changes of pungency and 2–3 leading flavour/taste attributes were traced using Time–Intensity procedure at pre-determined discrete time intervals. Most of T–I parameters of capsaicin pungency depended strongly on both, carrier complexity and capsaicin concentration. The three pairs of model soups and sauces suppressed pungency evoked by chili differently. Pungency intensity was consistently lower in sauces than in soups. Increasing chili level caused systematic but moderate or slight suppression of leading flavour attributes (more often in soups and less in sauces). Various taste quality (acidic, bitterness and saltiness) were differently affected by pungency. Quality changes and temporal migration of pungency sensation in the mouth contributed additionally to the complexity of interaction between pungency/leading flavour and taste attributes/carriers.     

Individual differences in responsiveness to oral sensations and odours with chemesthetic activity: Relationships between sensory modalities and impact on the hedonic response

Independent sensory modalities are related and showed covariations in prior literature. However, little is known on the relationship between oral sensations and nasal chemesthesis. This large-scale study aims (I.) to test the hypothesis that response to oral stimuli is related to responsiveness to odours with chemesthetic activity; and (II.) to explore the implications of these relationships on liking.Oral and olfactory responsiveness of 2205 Italians (18–65 years, men = 41%) were evaluated. Intensities of tastes, astringency and pungency were collected in water solutions and in four foods modulated for target sensations. Responses to bitterness of 6-n-propylthiouracil (PROP) was measured. Odour intensity and irritation were assessed for three pure odorants (L-Menthol, trans-anethole, (+)-α-Terpineol) stimulating nasal chemesthesis (respectively: TRPM8, TRPA1, TRPA1). Liking for odours and foods was measured. Specific intensity indices were developed for each sensation.Three clusters were identified based on taste intensity responses (Cl1, Cl2, Cl3). Cl1 (38%) was the most responsive to tastes, astringency, pungency, PROP and odours’ intensity and irritation. This hyper-responsive cluster showed the highest hedonic variation (the span of liking ratings for stimuli with varied tastant concentrations). Cl2 (24%) was intermediate for oral responsiveness (apart for sourness) and Cl3 (38%) was the least responsive. Cl2 and Cl3 did not differ in odours’ responsiveness (neither for perceived intensity nor for irritation). All sensory modalities were correlated but cross-correlations were higher when stimulating the same peripherical areas (oral vs oral more correlated than oral vs nasal). Results corroborate the idea of an overall high ‘sensory responsiveness’ covering different sensory modalities. Practical implications of the study are that less responsive subjects might require greater modifications in products formulations to modify their liking.     

Evaluation of trigeminal pungency perception of allyl isothiocyanate – A time intensity (TI) study

Allyl isothiocyanate, the primary pungent substance within mustard, horseradish, and wasabi, causes a burning sensation and a lachrymatory effect during consumption. In this time intensity study, the sensory perception of the chemical stimulus allyl isothiocyanate was evaluated in water-based, oil-based, and mustard recipe-based carrier matrices. The results indicate that perceived pungency intensity and time course of perception were both strongly dependent upon allyl isothiocyanate concentration and the composition of the carrier matrices. Increasing allyl isothiocyanate concentrations led to a significant (p < 0.05) increase in maximum intensity of pungency (I_max) in all tested carrier matrices. The intensity of pungency perception for allyl isothiocyanate decreased depending upon the specific matrix used. Specifically, this decrease occurred in the order oil-based carrier < mustard-based carrier < water-based carrier at similar allyl isothiocyanate concentrations. The values for end time of pungency perception (T_End) and duration of decreasing phase (DUR_Dec) indicate that increasing allyl isothiocyanate concentrations prolong the duration of pungency perception. Allyl isothiocyanate was perceived longer in water than in oil- and mustard-based carrier matrices.     

Determination of absolute threshold and just noticeable difference in the sensory perception of pungency

Absolute threshold and just noticeable difference (JND) were determined for the perception of pungency using chili pepper in aqueous solutions. Absolute threshold and JND were determined using 2 alternative forced-choice sensory tests tests. High-performance liquid chromatography technique was used to determine capsaicinoids concentration in samples used for sensory analysis. Sensory absolute threshold was 0.050 mg capsaicinoids/kg sample. Five JND values were determined using 5 reference solutions with different capsaicinoids concentration. JND values changed proportionally as capsaicinoids concentration of the reference sample solutions changed. Weber fraction remained stable for the first 4 reference capsaicinoid solutions (0.05, 0.11, 0.13, and 0.17 mg/kg) but changed when the most concentrated reference capsaicinoids solution was used (0.23 mg/kg). Quantification limit for instrumental analysis was 1.512 mg/kg capsaicinoids. Sensory methods employed in this study proved to be more sensitive than instrumental methods. Practical Application: A better understanding of the process involved in the sensory perception of pungency is currently required because "hot" foods are becoming more popular in western cuisine. Absolute thresholds and differential thresholds are useful tools in the formulation and development of new food products. These parameters may help in defining how much chili pepper is required in a formulated product to ensure a perceptible level of pungency, as well as in deciding how much more chili pepper is required in a product to produce a perceptible increase in its pungency.     

Lipase-catalyzed synthesis of pungent capsaicin analogues

Pungency in peppers (Capsicum spp.) is a sensation produced by a group of molecules known as capsaicinoids. Capsaicin has been reported as the capsaicinoid with the strongest pungency. Based on the molecular structure of capsaicin the enzymatic synthesis and pungent properties of structural analogues was investigated. These analogues were based on modification of the length of the acyl chain (from C4 to C16) and the chemical substituents of the aromatic ring (–OH and –OCH₃). The syntheses were carried out in 2-methyl-2-butanol with lipase B of Candida antarctica, with conversions ranging from 83% to 97.5%. The initial reaction rates were not significantly influenced by the nature of acyl-donor but rather by the substituents in the aromatic ring of the evaluated amines. The relative pungency of 10 capsaicin analogues was sensorially evaluated, using a sensory method for relative pungency. All the compounds were tested at a dose equivalent to 20 times the threshold capsaicin concentration. Two analogues were found pungent; the vanillylamides of caprylic (C-8) and capric (C-10) acids, showing a relative pungency of 66% and 36%, respectively, while the vanillylamides of caproic (C-6) and lauric (C-12) acids had a very low relative pungency (2.1% and 1.2%, respectively). From these results structural features related to pungency are discussed.     

Cross-modal interactions between taste and smell: Odour-induced saltiness enhancement depends on salt level

In recent years, health concerns related to salt have led to extensive research on low-salt foods. One major remaining issue is to reduce sodium content while still providing the salty fix, to maintain food appreciation, acceptance and choice. Using well-selected odours has been proposed to compensate for sodium chloride reduction in food, due to the cross-modal interactions between odour and taste. However, interactions between taste and odour, with regards to saltiness, remain poorly investigated. Moreover, although a few studies have assessed the influences of odour and sweet supra-threshold intensity on cross-modal interactions, none focused directly on how they influence saltiness. Therefore, the aim of the present study is to determine if the level of saltiness, i.e., the concentration of sodium chloride in aqueous solutions, influences odour-induced saltiness enhancement (OISE). A panel of 64 untrained panellists evaluated the saltiness of water solutions including salt and a tasteless odorant. Following a full factorial design, three concentrations of salt were used in conjunction with three aroma conditions. The results confirmed that OISE depends on odour-taste congruency but also clearly indicated that OISE depends on salt concentration (salty intensity): the saltiness of a low- or medium-salt-content solution increased significantly when subjects perceived simultaneously the congruent sardine aroma, but OISE was no more significant with high-saltiness solutions. This effect has to be taken into account when using OISE as a compensation strategy in low-salt food.     

Pungency in food perception and preference

Abstract

While sensations of pungency are characteristic of food in all cultures, relatively little attention has been given to trying to understand the role these sensations play in our perception of, and preference for, foods and food flavors. This review provides an overview of research on the psychophysics of the sensory system responsible for perception of pungency (the trigeminal nerve), current views on how preference for pungency develops, and the qualities of common pungent food ingredients and their interactions with food flavors. It is argued that understanding the role that pungency plays in foods is essential to successful development of acceptable food flavors, especially for those markets in Asia in which pungency is a defining characteristic of the cuisine.     

Synthesis and Characterization of Nano‐Encapsulated Black Pepper Oleoresin using Hydroxypropyl Beta‐Cyclodextrin for Antioxidant and Antimicrobial Applications

Previous studies have reported antimicrobial and antioxidant activity of black pepper oleoresin which is associated to its phenolic compounds and piperine. The ability of cyclodextrins to form an inclusion complex with a guest molecule could improve black pepper oleoresin application, bioavailability, and stability in foods. Hydroxypropyl beta‐cyclodextrin (HPBCD) inclusion complex with black pepper olereosin were synthesized using the kneading method and characterized for its physico‐chemical properties and its antioxidant and antimicrobial activities. Inclusion complex size was 103.9 ± 7.6 nm and indicated to be a polydisperse system. The entrapment efficiency was 78.3 ± 3.6%, which suggests that other constituents in black pepper oleoresin have higher affinities for HPBCD than piperine (major compound in black pepper oleoresin). Thermograms showed the disappearance of oxidation peaks of black pepper oleoresin, proving complex formation with HPBCD. Phase solubility results indicated 1:1 stoichiometric inclusion complex formation and an increase of black pepper oleoresin aqueous solubility with HPBCD concentration. Nano‐encapsulation with HPBCD did not affect (P > 0.05) total phenolic content; however, it enhanced (P < 0.05) black pepper oleoresin antioxidant activity. Black pepper oleoresin and its inclusion complex were analyzed for their antimicrobial activity against Escherichia coli K12 and Salmonella enterica serovar Typhimurium LT2. Both free and encapsulated black pepper oleoresin effectively inhibited bacterial growth within the concentration range tested. Black pepper oleoresin encapsulated in HPBCD was able to inhibit Salmonella at lower (P < 0.05) concentrations than its corresponding free extract. Therefore, black pepper oleoresin‐HPBCD nanocapsules could have important applications in the food industry as antimicrobial and antioxidant system.     

NaOH treatment reduces capsaicin content and pungency of ‘Makedoniko’ pepper (Capsicum annuum L.)

Pickled peppers are preferred by certain consumer groups at reduced pungency. To investigate the reduction in pepper pungency and capsaicin content, fresh ‘Makedoniko’ hot peppers were treated with 0, 0.5 or 1% NaOH before preserved in acid brine for 60 days. Pepper physicochemical traits were monitored following NaOH treatment and during preservation. Capsaicin content was measured in the beginning and at the end of preservation, and the peppers were also tested organoleptically. Preservation in acid brine induced the typical green–yellow product colour, increased firmness and decreased the dry mass in all treatments. NaOH‐treated pepper increased phenolics, chlorophyll and antioxidant content in dry mass during preservation faster than the control. Capsaicin content was reduced by 25 or 50% following 0.5 or 1% NaOH treatment, respectively. Pepper organoleptic pungency was also decreased following 1% NaOH treatment. NaOH reduces capsaicin content and pungency of ‘Makedoniko’ pepper, with minor effects on its processed product quality.     

Enhanced extraction of oleoresin from Piper nigrum by supercritical carbon dioxide using ethanol as a co‐solvent and its bioactivity profile

Pepper oleoresin was extracted using supercritical fluid extraction (SCF) from Piper nigrum berries. The conditions for maximum extraction of piperine were arrived at by calculating the solubility parameters of piperine and carbon dioxide using the Hildebrandt solubility equation. The effect of entrainers such as methanol, ethanol, and acetone was evaluated using theoretical modeling. The results predicted therefrom were validated experimentally. SCF at 250 bar/50 °C/60 min gave maximum relative extraction of 61.7 and 87.61% of oleoresin and piperine, while addition of 30% (vol/wt) ethanol as co‐solvent enhanced the yield to 95.9 and 184.7% under similar conditions of SCF extraction as compared to ethanol extraction for 6 hr. The oleoresins obtained showed comparable antioxidant, anti‐inflammatory, and antimicrobial activities with their respective controls. Hence SCF extraction of pepper using ethanol as a co‐solvent promises a rapid and enhanced recovery of oleoresin and its constituents with a good bioactivity profile.

Practical applications

Although SCF is a promising alternative for extraction of spice oleoresins, high cost of operation limits the use of this technology. In this work, process intensification of SCF extraction of black pepper lead to one step extraction and purification, along with high yield of oleoresin and the principle component piperine, eventually decreasing the cost of production. Thus, the highly concentrated SCF extracted oleoresins can have better replacement value for whole spices and better distribution in food and pharmaceutical sector.     

The effect of age,gender and noise sensitivity on the liking of food in the presence of background noise

The liking of food in the presence of background noise has been associated with the noise type and level. So far, however, there have been few studies investigating the non-acoustic factors associated with food perception in the presence of background noise. This study investigated the food liking due to three non-acoustic factors (i.e. gender, noise sensitivity and age) in the presence of background noise, relative to the ambient background noise (i.e. no noise conditions). Fifteen participants rated the liking of food via questionnaires. The perceptual relative food liking due to age, gender and noise sensitivity at different noise types and levels were presented. The results indicated that age, noise sensitivity and gender influence relative food liking. Females had lower liking ratings of food than males (p = 0.038). Noise sensitivity was also negatively correlated with the relative liking of food (r = −0.72, p < 0.001). Sensitive participants gave lower relative food liking ratings (p = 0.023). The older participants also gave lower relative food liking ratings (p = 0.01). A better understanding of acoustic and non-acoustic factor effects on food perception can be an important area of interest in noise management of dining areas. These results also provide an opportunity for future practical and educational applications. These include a better service that could be presented from food providers and more practical acoustic design of dining areas to suit different groups of people.     

Low-sodium roasted peanuts: effects of salt mixtures (NaCl,KCl and glycine) on consumer perception and purchase intent

The effects of ten treatment combinations of two salts (NaCl, KCl) and glycine were evaluated on low-sodium roasted peanuts. Consumers’ (N = 330, recruited from college campus) liking, emotions, perceived saltiness and bitterness intensity, satisfaction and purchase intent (PI) of peanuts were measured following a balanced incomplete block design (t = 10, k = 3, r = 9, b = 30, λ = 2, e₂ = 0.74). Emotions and PI were evaluated both before and after presenting a low-sodium health benefit message. Sodium content of peanuts was reduced from 140 mg Na/50 g peanuts to 41.67 mg Na/50 g without significantly affecting liking scores and with positive PI over 60%. In general, high bitterness and low saltiness intensity ratings negatively affected liking and satisfaction. Consumers expressed less satisfaction when perceived saltiness intensity was ‘Not Enough’ than when ‘Too Much.’ Based on optimisation analysis, any formulation within the range of 59-100/0-40/0-12.5% NaCl/KCl/Gly- representing a potential 37% sodium reduction past minimum ‘low sodium’ requirements- will yield an acceptable product.     

Potential of Szechuan pepper as a saltiness enhancer

The flavor profile, flavor enhancement, and saltiness modulation of Szechuan pepper (Zanthoxylum simulans) were analyzed to evaluate its effectiveness in lowering salt usage. The saltiness enhancing efficiency of Szechuan pepper and its salt-reduction properties were determined to be 28.74% and 22.32%, respectively. The saltiness enhancers were detected in the polar fraction and taste dilution analysis combined with half-tongue test determined the most potent saltiness enhancing components in chromatographic subfractions. Both spectroscopic analysis and sensory evaluation disclosed NaCl as the unexpected primary contributor of saltiness enhancement in this spice. It is the first known study revealing Szechuan pepper’s high salt content.