Synergistic effect of combining umami substances enhances perceived saltiness.

Umami substances have the potential to enhance the perception of saltiness and thus reduce sodium intake. Two sensory evaluation experiments were conducted, involving participants tasting salt solutions, and solutions with added umami substances at equal sodium concentrations. Umami substances included sodium glutamate (MSG), disodium inosinate (IMP), and the combination of them which has a synergistic effect and is a closer match to commonly-consumed foods. In Experiment 1, using the two-alternative forced-choice (2-AFC) method by 330 consumers, paired comparisons were conducted at three different sodium concentrations. The combination of MSG and IMP enhanced the perception of saltiness (p < .001 in the difference test), whereas presenting either umami substance in isolation failed to do so (p > .05 in the similarity test). Significant order effects occurred in paired comparisons. In Experiment 2, a two-sip time-intensity (TI) analysis with trained panellists verified these results and found that tasting MSG and IMP either simultaneously or successively enhanced saltiness perception at equal sodium concentrations. These findings indicate that the synergistic effect of umami substances may be the cause of saltiness enhancement, and represents a potential strategy for sodium reduction while satisfying the consumer demand for saltiness perception. Considering the application in food processing and in food pairing, umami substances can potentially be used to help to reduce salt intake in food consumption.

Enzymatic debittering of cheese flavoring and bitterness characterization of peptide mixture using sensory and peptidomics approach.

Peptides in cheese flavoring produced through proteolysis plus fermentation generated bitterness. Bitterness of individual peptide can be quantified using quantitative structure-activity relationship, where molecular mass (M), hydrophobicity, residues, C-terminal hydrophobic amino acids (C-HAAs), and N-terminal basic ones (N-BAAs) are crucial. However, their accumulative influence on the overall bitterness of peptide mixture remains unknown. This study delved into extensive proteolysis to debitter and to correlate the multi-influencing factors of peptides and the collective bitterness. As hydrolysis increased from 7.5 % to 28.0 %, bitterness reduced from 5.0 to 0.3-2.7 scores, contingent on proteases used, in which FU was optimal. The overall bitterness cannot be predicted through the summation of individual peptide bitterness, which depended on M (0.5-3 kDa) and 5-23 residues, followed by N-BAAs and C-HAAs. Analysis of enzymatic cleavage sites and substrate characteristics revealed, to more effectively debitter bovine milk protein hydrolysates, proteases specifically cleaving Pro, Leu, Phe, and Val were desired.

Characterization of the key nonvolatile metabolites in Cheddar cheese by partial least squares regression (PLSR), reconstitution, and omission.

Cheddar cheese was desirable by consumers worldwide due to its characteristic taste and aroma, but limited information was available about taste contributors. Therefore, sensory profiles of natural Cheddar cheeses were investigated by quantitative descriptive analysis (QDA). Umami, salty, and brothy attributes were the principal differential attributes. Nonvolatile metabolites were analyzed to decipher their taste contributions, of which free amino acids (FAAs) and organic acids recorded the most considerable differences. The key taste compounds were identified by partial least squares regression (PLSR), reconstitution, and omission tests. NaCl and glutamic acid (Glu) were the primary contributors of salty and umami tastes, respectively. Sourness was synergistically affected by organic acids and Glu. Despite their limited taste impacts, the remaining amino acids intensified sourness and saltiness when mixed with Glu. Organic acids (especially in combination) and NaCl exhibited significant taste enhancements. These results provided deep insight into crucial nonvolatile metabolites promoting Cheddar cheese tastes.

Dynamic characteristics of sweetness and bitterness and their correlation with chemical structures for six steviol glycosides.

Time-intensity (TI) dynamic sensory characterization was used to evaluate the temporal sweet and bitter perception of six commonly available steviol glycosides (Rubusoside, Stevioside, Rebaudioside C, Rebaudioside A, Rebaudioside D and Rebaudioside M). All parameters extracted from TI curves significantly varied among the six samples for both sweetness and bitterness. Compared to other compounds, Rebaudioside M and Rebaudioside D had faster onset of sweetness, quicker decay of aftertaste, and were nearly devoid of bitterness. Conversely, Rubusoside and Stevioside demonstrated an immediate distinct bitter taste and lingering aftertaste. Based on these results, a further investigation into the relationship between temporal properties and chemical structures was conducted. It was found that fewer glucosyl groups on C-19 would result in shorter time for initial stimulation and longer perception of bitterness, whereas more glucosyl groups on C-13 could trigger a faster increase and stronger intensity of sweetness. A shorter time to the peak for sweetness was obtained when the ratio of the number of glucosyl groups on C-13 to that on C-19 was lower, although there was no such effect on bitter taste. These relationships were explained by the adsorption and desorption of these compounds on the taste receptors. Higher numbers and larger sizes of substitutions at the C-19 position of steviol glycosides can increase their desorption percentages and lead to a quicker decay of sweetness. Meanwhile, compounds with fewer glucosyl groups, such as Rubusoside and Stevioside, presented lower desorption and thus longer bitter aftertaste. Overall, the addition of glucosyl groups would generate stronger sweetness and less bitterness if the substituent number on C-13 was closer to that on C-19. These findings conveyed insights into how to modify steviol glycosides to enhance their quality as sweeteners.

The improvement of texture properties and storage stability for kappa carrageenan in developing vegan gummy candies.

BACKGROUND: As plant-based foods have become more mainstream in recent years, carrageenan has been used to replace animal-derived gelatin in confectionery products. However, texture defects and water seepage during storage limit the development of kappa carrageenan (KC) gummy candies. RESULTS: This study evaluated the effects of hydrocolloids on the texture properties and storage stability of KC gummy candies. The results showed that 4 g kg-1 carboxymethylcellulose (CMC) composited with 20 g kg-1 KC formed a flexible gummy candy with low fragility and limited water seepage during storage. Further investigation revealed that 4 g kg-1 CMC promoted side-by-side intermolecular aggregation of KC helices through hydrogen bonding, which stabilized a denser network structure compared to the pure KC hydrogel. However, high CMC proportions (8-12 g kg-1 ) led to electrostatic repulsion that dominated in the system, inhibiting the gel-forming process and thus resulting in a weak gel structure with accelerated syneresis. CONCLUSION: This study found that 4 g kg-1 CMC was able to improve the flexibility and decrease unacceptable fragility of KC gummy candies, with water seepage decreased during storage significantly. It provided preliminary evidence for utilizing hydrocolloids to adjust texture and control water migration in KC gels, and has potential to promote wide development of vegan gummy candies. © 2021 Society of Chemical Industry.

Consumers with high frequency of 'just about right' in JAR scales may use lower cognitive effort: Evidence from the concurrent 9-point hedonic scale and CATA question.

JAR scales are widely used to evaluate the suitability of attributes and guide product optimization. However, the reliability and validity of the results from JAR scales had been widely doubted. In the current research, it was hypothesized that respondents with high just about right (jar) frequency may have more satisficers according to Krosnick's survey satisficing theory, herein they were more likely to employ low cognitive effort in the tests. To search relevant evidence to prove this, a strategy of indirect method was employed that consumer with different jar frequencies may also perform differently in other concurrent tests such as hedonic scaling and CATA questions. A total of 716 consumers were recruited in four studies with four different sets of products involving coffee and chrysanthemum tea. These consumers were then divided into two groups in each study according to their jar frequency to examine the above hypothesis and their performance on the concurrent tests were compared between the two groups. It was found that consumers with high jar frequency tended to use a narrower range of scales on 9-point hedonic scale, and use terms more narrowly and repeatedly in CATA questions. This confirmed the above hypothesis. Meanwhile, the low cognitive effort could noticeably influence responses in other questions. For instance, it led to lower product discrimination based on hedonic scores when samples were similar and altered results of related to terms discrimination and term configurations in CATA questions. Thereby, survey satisficing problem should be taken seriously in both experimental design and statistical analysis in consumer testings.

Impact of consumption frequency on generations of sensory product profiles using CATA questions: Case studies with two drink categories.

Check-All-That-Apply (CATA) is a very popular tool for rapid sensory profiling in consumer research. Yet, consumers' dietary habits, such as consumption frequency, has been neglected in regard to the impact, if any, on CATA question responses. The present work aimed to fill this gap, by focusing on the effect of different consumption frequencies with four studies (N = 686). Two categories of drink products were involved, chrysanthemum tea and instant coffee. For each category, two sets of products were prepared to constitute two levels of difference between samples (larger vs. smaller). Consumers were classified into high- and low-consumption groups according to their consumption frequencies of each focal product; the size of these subgroups ranged from 54 to 130. Overall, the two groups did not produce large discrepancies from each other when constructing sensory profiling of the tested samples with CATA questions as well as the stability of sample configurations. However, there were some nuances between them. In the evaluation of chrysanthemum tea samples, the higher-consumption group of consumers presented better discrimination than the lower-consumption group while this was reversed for coffee samples. This might be mainly attributed to the fact infrequent consumers were more sensitive to such negative attributes as "strong chrysanthemum smell for chrysanthemum samples, earthy for coffee samples". Further, despite the higher stability obtained with larger sizes of difference between samples in Studies 3 and 4, in general, the effect of size of differences within sample sets was not significant between different consumption groups. To more effectively contribute to refinement of methodological guidelines for CATA questions, more validation work is needed.

Paired preference tests and placebo placement: 2. Unraveling the effects of stimulus variance.

From the literature on paired preference testing, there has been disagreement regarding whether a placebo pair would have a significantly higher frequency of 'no preference' responses if it were to be placed for assessment after its corresponding target pair rather than before. This can be important, because the higher the frequency of 'no preference' responses in the placebo pair, the more powerful will be any chi-squared related analysis, which determines whether the target pair indicates a significant preference or not. In the first paper in this series, it was shown, that indeed a placebo placed after the target pair induced a higher proportion of consumers to respond with a 'no preference'. However, the response was uneven. For some stimuli, the response was strong and significant, for others it was weaker and not significant. It was hypothesized that the weak response could be due to greater variance among the individual stimuli in the placebo sample to be tasted. The effect was confirmed using a priori chosen high and low variance stimuli. Further evidence was obtained from predictions for preference tau criterion levels and frequency of preference changes between two target pairs. All these indicated that the weaker response of some stimuli was due to a higher level of variance among the individual stimuli.

The 9-point hedonic scale: Using R-Index Preference Measurement to compute effect size and eliminate artifactual ties.

214 consumers used the verbal 9-point hedonic scale to assess 4 types of flavor coated peanuts and 4 types of flavored teas. They used the traditional ANOVA/LSD analysis to provide mean values derived from the 9-point hedonic scale along with measures of significant difference. However, these data did not provide effect sizes. They did not give direct measures of the strength of preference between the various products, which was the main interest. Accordingly, effect sizes were computed. For this, each consumer had also ranked their preferences as they made their ratings on the 9-point hedonic scale. From these, R-Index values were computed to provide the percentages of consumers, who preferred each product to every other product. These direct measures of effect size completed the analysis begun by the ANOVA analysis of the set of mean scores. Also, the measures were nonparametric and avoided issues of the validity of a parametric statistical analysis. They also avoided the problem with the traditional analysis when products in the same scale category are attributed the same scores, when they are not equally liked. Experiment 2, using 207 consumers indicated that this problem was only serious enough to reduce the power of the traditional analysis, compared with the R-Index Preference Measurement, when the number of products being tested approached a dozen say, for product optimization.

Applying Disruptive Preference Test Protocols to Increase the Number of "No Preference" Responses in the Placebo Pair, Using Chinese Consumers.

One form of paired preference test protocol requires consumers to assess 2 pairs of products. One is the target pair under consideration, while the other is a putatively identical pair named the "placebo pair" which is also presented as a control. Counterintuitively, the majority of consumers report preferences when presented with the placebo pair. Their response frequencies are hypothesized to be those of consumers having "no preference" and are compared with the response frequencies elicited by a target pair, to determine whether the target pair elicits significant preferences. The primary goal of this paper was to study the robustness of 2 new so called disruptive protocols that reduced the proportion of consumers, who reported preferences when assessing a putatively identical pair of products. For this task, the tests were performed in a different language, in a different country, using different products from before. The results showed that the proportion of consumers reporting preferences for the placebo pair was reduced, confirming earlier work. Also, comparison of d' values showed a lack of significant overall differences between the placebo and target pairs, while chi-squared analyses indicated significant differences in the response frequencies. This indicated that the sample was segmented into 2 balanced groups with opposing preferences.

Paired preference testing: False preferences and disruptive protocols.

This review introduces recent changes regarding measurement of preferences brought about by the discovery of false preferences that occur with paired preference testing. Testing protocols are examined critically. False preferences result from a response bias elicited by factors distinct from sensory properties of products being tested that can distort results. Statistical approaches to circumventing this problem are examined. Alternative methods are being developed to eliminate false preferences based on understanding information processing in the brain. This has led to development of disruptive experimental preference testing protocols based on hypothesized use of processing subroutines in the brain to protect the central processing system from overload. These disruptive protocols suppress response bias. Paired preference testing is designed to predict consumer behavior. A paucity of studies addressing whether they do is put into perspective.