Classification of Japanese Pepper (Zanthoxylum piperitum DC.) from Different Growing Regions Based on Analysis of Volatile Compounds and Sensory Evaluation.

The Japanese pepper (Zanthoxylum piperitum DC.) is an attractive plant that is highly palatable and benefits human health. There are several lineages of pepper plants in Japan. However, the classification of each lineage by analyzing its volatile compounds and studies on the effects of differences in volatile compounds on human flavor perception have not been performed in detail. Herein, we conducted gas chromatography (GC) and GC/mass spectrometry (GC/MS) analysis of volatile compounds and sensory evaluation of flavor by an analytical panel using 10 commercially available dry powdered Japanese pepper products from different regions. GC and GC/MS analysis detected limonene, ß-phellandrene, citronellal, and geranyl acetate as the major volatile compounds of Japanese peppers. The composition of volatile compounds showed different characteristics depending on the growing regions, and cluster analysis of composition classified the products into five groups. The sensory evaluation classified the products into four groups, and the results of both classifications were in good agreement. Our results provide an important basis for proposing cooking and utilization methods that take advantage of the unique characteristics of each lineage based on scientific evidence.

Elucidation of Japanese pepper (Zanthoxylum piperitum De Candolle) domestication using RAD-Seq.

Japanese pepper, Zanthoxylum piperitum, is native to Japan and has four well-known lineages (Asakura, Takahara, Budou, and Arima), which are named after their production area or morphology. Restriction-site associated DNA sequencing (RAD-Seq) was used to analyse 93 accessions from various areas, including these four lineages. Single nucleotide variant analysis was used to classify the plants into eight groups: the Asakura and Arima lineages each had two groups, the Takahara and Budou lineages each had one group, and two additional groups were present. In one Asakura group and two Arima groups, the plants were present in agricultural fields and mountains, thus representing the early stage of domestication of the Japanese pepper. The second Asakura lineage group was closely related to plants present in various areas, and this represents the second stage of domestication of this plant because, after early domestication, genetically related lineages with desirable traits spread to the periphery. These results demonstrate that domestication of Japanese pepper is ongoing. In addition, this study shows that spineless plants are polyphyletic, despite the spineless lineage being considered a subspecies of Japanese pepper.

Influence of physical properties on the taste and flavor of strawberry jam.

This study investigated the influence of the type and concentration of pectin on the sensory attributes and physical properties of a model strawberry jam. The methods used for the sensory evaluation and determination of physical characteristics that affect human taste and flavor perception are outlined. Increasing pectin concentration altered the solid (elastic) properties of the model strawberry jam. Each sensory attribute showed high correlation with various physical properties as determined by viscosity measurements. These results allowed us to predict the human oral cavity conditions during taste and flavor perception. From this study, it is clear that humans assess the physical properties of foods by the tongue movements and adjustments in the oral cavity conditions according to the taste and flavor characteristics.

Estimating the sensory qualities of tomatoes using visible and near-infrared spectroscopy and interpretation based on gas chromatography-mass spectrometry metabolomics.

The ability to estimate the sensory quality of intact tomatoes rapidly and non-destructively using visible and near-infrared spectroscopy (Vis-NIRS) is important for the tomato industry. In this study, a combination of partial least squares regression (PLSR) analysis and the stepwise selectivity ratio (SWSR) method was used to study the ability of Vis-NIRS to predict 19 sensory attributes in intact tomatoes. The PLSR models constructed based on the informative wavelengths selected by the SWSR method predicted 8 sensory attributes well, particularly the sweetness attribute (correlation coefficient of validation of 0.92). Moreover, based on the tomato metabolites determined by GC-MS analysis, high intercorrelations between sensory attributes, metabolites, and the selected informative wavelengths were found through principal component analysis, as well as the high correlation coefficients between them. The results confirm the feasibility and reliability of Vis-NIRS and the informative wavelengths selected by SWSR to predict the sensory quality of whole tomatoes.

Standardization of tomato juice tastes using a taste sensor approach.

To enable the taste evaluation of many food samples at a time as well as the comparison of taste evaluation data acquired at different times, a standardization method for taste intensities was developed by a combination of a taste sensor system and a standard solution prepared with taste substances. In the case of tomato juices, citric acid, sucrose, and monosodium glutamate were used as standard taste substances for sourness, sweetness, and umami taste, respectively. Each standard point of the taste intensities was determined using only one standard solution including these standard substances. The taste intensity was described as a value on a scale based on discrimination thresholds of human gustation, where intensities of sourness, sweetness, and umami taste of the tomato juices were classified into multiple levels. Organoleptic evaluation supported these results. Validation for the present standardization method revealed that this approach has enough precision for practical tomato taste evaluation.

Flavor and Texture Characteristics of 'Fuji' and Related Apple (Malus domestica L.) Cultivars, Focusing on the Rich Watercore.

Watercore is a so-called physiological disorder of apple (Malus domestica L.) that commonly occurs in several well-known cultivars. It is associated with a rapid softening of the flesh that causes a marked changed in flavor and texture. In Asia, apples with watercore are preferred and considered a delicacy because of their enhanced sweet flavor. The 'Fuji' cultivar, the first cultivar with rich watercore that is free from texture deterioration, has played a key role in the development of the market for desirable watercored apples. This review aimed to summarize and highlight recent studies related to the physiology of watercore in apples with special focus on 'Fuji' and related cultivars.

Relationship between sensory analysis for texture and instrument measurements in model strawberry jam.

The primary objective of this study was to investigate the correlations between instrument measurements and sensory attributes of strawberry jam. For this purpose, a series of low sugar strawberry jams were prepared by using different contents of pectin from different sources, which were evaluated by sensory analysis for sensory attributes and by instrument measurements for specific physical properties. Model strawberry jams showed an elastic behavior that increased with higher low-methoxyl (LM) pectin content. These results showed that the apparent viscosity from viscosity measurements was highly correlated with each sensory attribute. As jam is a non-Newtonian fluid, the apparent viscosity was dependent on the shear rate. Moreover, the secondary objective of this study was to discern the physical properties affecting human texture perception based on these relationships. Hence, the instrumental texture perception based on the oral cavity condition was able to predict human texture perception based on the shear rate, which was obtained from the apparent viscosity. These results indicated that human texture perception is judged by apparent viscosity as determined by controlling tongue movement and oral cavity condition (e.g., temperature, saliva, and shear rate). PRACTICAL APPLICATIONS: We could demonstrate the importance of texture measurement using replicated oral processing for each sensory attribute. Specifically, viscosity measurement results indicated that shear rate is a very important factor for texture perception. Moreover, our findings clarified that human texture perception is modified by apparent viscosity corresponding to shear rate. We anticipate that this technology might be applied as a measure of apparent viscosity to control texture for jam quality improvement.

Optimising aroma quality in curry sauce products using in vivo aroma release measurements.

Reducing fat content in foods to meet consumers' preferences and to address the obesity issue is a key task for food manufacturers but simply reducing fat content affects aroma quality adversely. Measuring the aroma release from regular and low-fat samples during eating to rebalance the aroma release has proved successful in model systems. Here, the reformulation of the spice content in a low fat curry sauce is described. Volatile markers of the key spices (coriander, cumin and turmeric) were selected and used to measure aroma release in regular (10 g oil/100 g) and low (2.5 or 5 g oil/100 g) fat sauces. Regression models were used to adjust the ingredient formulation so that the aroma release profiles in vivo were the same for the regular and reduced oil curry sauces and sensory analysis showed no significant difference between these samples. Despite the complexity of spice aromas, rebalancing was successful.

Superiority of experts over novices in trueness and precision of concentration estimation of sodium chloride solutions.

Several studies have reported that experts outperform novices in specific domains. However, the superiority of experts in accuracy, taking both trueness and precision into consideration, has not yet been explored. Here, we examined differences between expert and novice performances by evaluating the accuracy of their estimations of physical concentrations of sodium chloride in solutions while employing a visual analog scale. In Experiment 1, 14 experts and 13 novices tasted 6 concentrations of the solutions until they had learned their intensities. Subsequently, they repeatedly rated the concentration of 3 other solutions in random order. Although we did not find a difference between the performances of the 2 groups in trueness (difference between rating and correct concentration), the precision (consistency of ratings for each participant) of experts was higher than that of novices. In Experiment 2, 13 experts who had participated in Experiment 1 and 10 experts and 12 novices who had not participated in Experiment 1 rated the salt concentration in sodium chloride/sucrose mixtures in the same way as in Experiment 1. Both trueness and precision of performance were higher in both expert groups than in the novice group. By introducing precision and trueness parameters, we succeeded in quantifying the estimations of experts and novices in rating the concentration of solutions, revealing experts' superiority even for a task they had not been trained for.

Texture of Sliced Cucumbers Measured by Subjective Human-Bite and Objective Instrumental Tests.

To determine an effective method to evaluate the texture of cucumbers, human-bite measurement using a multiple-point sheet sensor and instrumental tests using wedge probes with various angles and a cylindrical probe were conducted. To detect small differences in texture, cross-sectional slices taken from the middle part of a cucumber fruit were served at 4 or 22C. The 60°-wedge probe that could completely divide samples like human incisors performed best compared with sharper wedges or cylindrical probe that partly broke the tissue. The human-bite force for cucumber slices of 4C was significantly lower than that of 22C. Breaking force and energy with the wedges of 60 and 30° in the compression test and those for flesh puncture test demonstrated a similar temperature effect. A faster compression speed close to the human-bite speed (20 mm/s) was necessary to detect the significant temperature effects. PRACTICAL APPLICATIONS: The texture of cucumber was analyzed more precisely using a wedge probe with an angle of 60° inserted into sectional slices of the samples similar to the action of human front teeth that completely cut off the section. A cylindrical probe could insert only part of the cucumber tissues and a blade or a sharper wedge probe partially broke the slices to the depth which the probe reached. Faster test speed (>10 mm/s) close to the average speed of human bite is preferred to detect temperature effects on fracture force. If there are some differences in breaking properties of cucumbers, the proposed conditions of compression test with a 60° wedge at 20 mm/s will detect delicate differences as those due to serving temperature were small.

Effectiveness of superheated steam and gas catalytic infrared heat treatments to inactivate Salmonella on raw almonds.

The majority of the almond-related outbreaks have been associated with Salmonella. Therefore, it is necessary to find an effective method to inactivate these organisms on the raw almond before distribution in the market. This study was conducted to assess the effectiveness of superheated steam (SHS) treatments followed by catalytic infrared (IR) heat treatment to inactivate Salmonella populations on raw almond and to determine the effect of these treatments on the quality of raw almond. It has been found that SHS treatment for 70 seconds followed by catalytic IR heat treatment for 70 seconds was able to reduce 5.73 +/- 0.11 log CFU/g Salmonella population, and no survivors were found in the enrichment medium. The overall visual quality parameters of both treated and nontreated almonds were found within the acceptable limit. Therefore, SHS treatments for 70 seconds followed by catalytic IR heat treatment for 70 seconds could be an effective decontamination method for raw almonds.

Electromyographic measurement of eating behaviors for buckwheat noodles.

The objective of this study was to analyze human eating behaviors in chewing and slurping buckwheat noodles. We used electromyography to measure the activity of the jaw-closing, jaw-opening, and lip-closing muscles while healthy adults ate one mouthful of buckwheat noodles. Slurping the noodles required a longer mastication period but smaller muscle activity per movement than chewing the same samples. Total muscle activity was greater in slurping. Slurping also showed a longer average cycle time but greater variances in the cycle time than rhythmical chewing. The mechanical properties of buckwheat noodles significantly differed between the noodle types (half-raw and dry), but the human mastication variables for the two types of noodles were not significantly changed within a subject. Both types of noodles kept for 10 min at 23 degrees C after being cooked could be consumed with less mastication effort than those immediately served, and this observation corresponded to softening of the noodles during the standing time.

Characterization of food physical properties by the mastication parameters measured by electromyography of the jaw-closing muscles and mandibular kinematics in young adults.

The relationship between the physical properties of solid food and the masticatory parameters is clarified. Eight solid foods of varying physical properties were chosen. Electromyography of the jaw-closing muscles and mandibular kinematics in eleven young subjects were recorded. The masticatory parameters were derived from the recorded data for the entire mastication process, for the first bite, and in the early, middle, and late stages of mastication. After calculating values relative to the mean value for each subject, nine parameters representing each group were chosen through a cluster analysis. Three principal components were extracted, each of them related to the masticatory time and cycle, minimum jaw opening at the early stage of mastication, and masticatory force. The principal component scores for each food were different, except for one combination in which the physical properties under large and extra-large deformations were similar, despite different breaking properties or small deformation properties. The masticatory parameters did not correlate with the physical properties of food measured for small deformation.

Modulation of biting procedures induced by the sensory evaluation of cheese hardness with different definitions.

This study seeks to clarify the bite process in individuals who assess cheese hardness to confirm the relationships among hardness definitions, their causative bite procedures, targeted intra-oral mechanical events, and judgment. Subjects were required to bite and evaluate samples using two different definitions of hardness. We measured an intra-oral bite time-force profile using a tactile pressure-measurement system with a sheet sensor unobtrusively inserted into the subject's mouth along with a sample. The first bite profile was an exploratory procedure adjusted to optimize perception of the designated textural attribute. From the temporal modification of the bite profile, we could estimate the bite parameter that was targeted as the sensory information for a particular texture attribute. We examined inter-definition and inter-subject variations in the relationship between hardness judgment and its sensory source estimated from the bite procedure. We demonstrated that the bite measurement could elucidate both the bite procedures and sensory information for hardness evaluation. Different definitions induced different bite procedures that resulted in a change in the sensory signal. The definition also affected inter-subject variability in bite procedures and sensory-judgment correspondence.

Visual illusion in mass estimation of cut food.

We investigated the effect of the appearance of cut food on visual mass estimation. In this experiment, we manipulated the shape (e.g., a block, fine strips, or small cubes) of food samples of various masses, and presented them on a CRT display as stimuli. Eleven subjects participated in tasks to choose the picture of the food sample which they felt indicated a target mass. We used raw carrots and surimi (ground fish) gel as hard and soft samples, respectively. The results clearly confirm an existence of an illusion, and this indicates that the appearance of food interferes with visual mass estimation. Specifically, participants often overestimated the mass of finely cut food, especially fine strips, whereas they could accurately estimate the mass of block samples, regardless of the physical characteristics of the foods. The overestimation of the mass of cut food increased with the food's actual mass, and was particularly obvious with increases of apparent volume when cut into fine strips. These results suggest that the apparent volume of a food sample effects the visual estimation of its mass. Hence we can conclude that there are illusions associated with the visual presentation of food that may influence various food impressions, including satisfaction and eating behaviour.

Textural evaluation of rice cake by chewing and swallowing measurements on human subjects.

The difficulty in masticating and swallowing rice cake was quantified. Healthy subjects ate pieces of rice cake (9 g and 3 g) and a modified product (9 g). We used electromyography to measure the activity of the jaw-closing and -opening muscles during chewing, as well as the suprahyoid muscle activity, laryngeal movement, and sound during swallowing. The smaller the rice cake, the shorter the mastication time, the fewer the number of chews, and the less the jaw-closing muscle activity. A modified rice cake product (9 g) was consumed with less mastication effort than the standard rice cake (9 g) and with the same effort as the standard (3 g). Both the sample amount and texture influenced mastication, although neither factor caused a significant difference in swallowing characteristics. These observations suggest that swallowing was induced when the bolus properties became suitable for swallowing, as healthy subjects could adjust their mastication technique according to the food amount and texture.

Prefrontal activity during flavor difference test: application of functional near-infrared spectroscopy to sensory evaluation studies.

Sensory evaluation (SE) of food attributes involves various levels of cognitive functions, yet not much has been studied about its neural basis. Using multi-channel functional near-infrared spectroscopy (fNIRS), we examined the activation of the anterior portion of the lateral prefrontal cortex (LPFC) of 12 healthy volunteers during the SE of tea samples. The experimental task used corresponded to the early phase of the same-different test, and required subjects to attentively taste tea samples and memorize their flavors. To isolate activation associated with the cognitive functions involved in the task, we contrasted the results with those achieved by a control (Ctl) task during which subjects held familiar tea samples in their mouths without actively evaluating their flavor. We probabilistically registered the fNIRS data to the Montreal Neurological Institute standard brain space to examine the results as they correspond with other published neuroimaging studies. We found significant activation in the left LPFC and in the right inferior frontal gyrus. The activation pattern was consistent with earlier studies on encoding of other sensory stimuli, with cortical regions supposed to be involved in semantic and perceptual processing. This research makes a start on characterizing the cognitive process employed during SE from the neuroimaging perspective.

Mastication effort estimated by electromyography for cooked rice of differing water content.

The objective of this study was to quantify the mastication effort for cooked rice. We analyzed mastication patterns while normal subjects ate a spoonful of cooked rice that had been prepared by cooking with different amounts of water (1.5, 2.0, 3.0, and 4.0 times the water to rice weight). The rice samples were served with the same weight, same volume and same solid content, and electromyography (EMG) of the masticatory muscles was measured. The texture of the four cooked rice samples was instrumentally analyzed by the two-bite method. The number of chews, masticatory time, and jaw-closing muscle activities per chew evaluated by EMG were higher in the rice sample cooked with least water, which exhibited a high firmness value in the instrumental test. Rice cooked with 4.0 times the amount of water exhibited the longest jaw-opening duration, which was related to the adhesiveness value in the instrumental test. The ratio of jaw-opening muscle activity to the preceding jaw-closing muscle activity was lower for the rice containing least water, this corresponding to the area ratio (balance degree) in the instrumental test. Softer rice containing more water reduced the total mastication effort until swallowing because it required a shorter mastication time. It was not difficult for the softer rice with high density to be ingested in greater weight, decreasing the mastication effort for a certain amount.

Measurement of bite force variables related to human discrimination of left-right hardness differences of silicone rubber samples placed between the incisors.

This study was designed to examine human subjects' ability to discriminate between spatially different bite pressures. We measured actual bite pressure distribution when subjects simultaneously bit two silicone rubber samples with different hardnesses using their right and left incisors. They were instructed to compare the hardness of these two rubber samples and indicate which was harder (right or left). The correct-answer rates were statistically significant at P < 0.05 for all pairs of different right and left silicone rubber hardnesses. Simultaneous bite measurements using a multiple-point sheet sensor demonstrated that the bite force, active pressure and maximum pressure point were greater for the harder silicone rubber sample. The difference between the left and right was statistically significant (P < 0.05) for all pairs with different silicone rubber hardnesses. We demonstrated for the first time that subjects could perceive and discriminate between spatially different bite pressures during a single bite with incisors. Differences of the bite force, pressure and the maximum pressure point between the right and left silicone samples should be sensory cues for spatial hardness discrimination.

Effects of cross-sectional area on human bite studied with raw carrot and surimi gel.

The effects of the cross-sectional area of food samples on bite force with molar teeth were investigated using raw carrots and surimi gels. We evaluated human bite force for food samples with different sizes between the upper and lower molars using a multiple-point sheet sensor and electromyography (EMG). The bite force curve and EMG clearly showed textural characteristics of the carrot and gel. In particular, the first peak in the bite curves corresponded to breaking point in the compression test. With increasing cross-sectional area of both foodstuffs, the bite force and contact area increased and the average stress to which the specimen was subjected (mean stress) tended to decrease, while the stress produced between the teeth and the specimen (active stress) did not change. Chewing rhythm and EMG activities were not greatly influenced by sample size. These findings suggest that higher bite force might cause difficulty in biting food with a larger cross-sectional area.