Comparison of methods to monitor liking of food during consumption

Unraveling the difference in flavor characteristics of Huangjiu fermented with different rice varieties using dynamic sensory evaluation and comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry

To investigate the specific differences in flavor characteristics of Huangjiu fermented with different rice varieties, dynamic sensory evaluation, comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC × GC-qMS) and multivariate statistical analysis were employed. Dynamic sensory evaluation methods including temporal dominance of sensations (TDS) and temporal check all that apply (TCATA) were applied to explore the differences and variations in sensory attributes. The sensory results showed that the intensity of astringency and post-bitterness in the Huangjiu fermented with glutinous rice was weaker while ester and alcoholic aroma were more prominent than the one fermented with japonica rice. The results of free amino acids and aroma compounds analysis indicated that the amino acids were mainly sweet and bitter amino acids, and some key aroma compounds were predominant in the Huangjiu fermented with glutinous rice, such as ethyl butyrate (OAV: 38-59), 3-methylthiopropionaldehyde (OAV: 47-96), ethyl caprylate (OAV: 30-38), while nonanal, phenyl acetaldehyde and vanillin contributed significantly to the Huangjiu fermented with japonica rice. The multivariate statistical analysis further confirmed that 17 compounds (VIP > 1 and p < 0.05) could be supposed to be the key compouns that cause significant flavor differences in Huangjiu samples fermented with different brewing rice. Moreover, partial least-squares analysis revealed that most compounds (ethyl butyrate, 3-penten-2-one, isoamyl acetate, and so on) correlated with ester and alcoholic aroma. The results could provide basic data and theoretical basis for the selection of raw materials in Huangjiu.

Comparing consumer liking of beef from three feeding systems using a combination of traditional and temporal liking sensory methods

Research on the effects of animal diet on consumer liking of beef has yielded conflicting results. Currently it is unknown whether dynamic changes occur in liking during consumption of beef. This study applied a combination of traditional and temporal (free and structured) liking methods to determine consumer liking of beef derived from animals that were fed grain (GF), grass silage plus grain (SG) or grazed grass (GG) during finishing. Three separate panels of beef eating consumers (n = 51; n = 52; n = 50) were recruited from Teagasc Food Research Centre, Dublin, Ireland to assess striploin steaks from animals fed either GF, SG, or GG. Using the free temporal liking (TL) method, results revealed that beef from GF animals was liked significantly less (p ≤ 0.05) in terms of overall liking, tenderness and juiciness, when compared to steaks from the SG and GG animals. These effects were not observed using the structured TL or traditional liking methods. Further analysis showed the evolution of scores over time was significant (p ≤ 0.05) for all attributes using the free TL method. Overall, the free TL method yielded more discriminative data and was perceived as easier to perform by consumers compared to the structured TL method. These results show that the free TL method may provide an opportunity to elicit more in-depth information regarding consumer sensory response to meat.

A Timely Application-Temporal methods, past, present, and future

Eating is a dynamic experience, and temporal sensory methods have been proposed to document how products change over the course of consumption or use (nonfood). A search of online databases yielded approximately 170 sources related to temporal evaluation of food products that were compiled and reviewed. This review summarizes the evolution of temporal methodologies (past), offers guidance in selecting appropriate methods (present), and provides insights into the future of temporal methodologies in the sensory space. Temporal methods have evolved to document a variety of characteristics in food products including how the intensity of a specific attribute changes over time (Time-Intensity), which specific attribute is dominant at each time during evaluation (Temporal Dominance of Sensations), which attributes are present at each time point during evaluation (Temporal Check-All-That-Apply), and many others (Temporal Order of Sensations, Attack-Evolution-Finish, and Temporal Ranking). In addition to documenting the evolution of temporal methods, this review considers the selection of an appropriate temporal method based on the objective and scope of research. When choosing a temporal method, researchers should also consider the selection of panelists to perform the temporal evaluation. Future temporal research should focus on validation of new temporal methods and explore how methods can be implemented and improved to add to the usefulness of temporal techniques for researchers.

Impact of 'free-from' and 'healthy choice' labeled versions of chocolate and coffee on temporal profile (multiple-intake TDS) and liking

Product reformulation for obtaining "free-from" or "healthy choice" versions may confer significant changes in sensory characteristics which could not meet consumer expectations in terms of sensory perception. Therefore, this paper aims to evaluate the influence of formulations of different product categories on their dynamic sensory profile and consumer acceptability. A sensory panel of 23 semi-trained assessors evaluated two product categories, chocolate and milk coffee, using Temporal Dominance of Sensations (TDS) over three consecutive intakes/sips (multiple-intake TDS) on two replications. TDS allowed us to describe the dynamic profile of classic products over the three intakes and to identify differences in the sensory temporal profile compared to their 'healthier choice' reformulated versions. For the chocolate category, increasing the cocoa and the reduction of lactose content mainly influenced the dominance of sweetness, dairy, cocoa, crunchy and bitterness attributes. No sugar addition and absence of caffeine (decaffeinated version) in ready to drink milk coffee beverage modified temporal perception of sweetness, bitterness, coffee flavor and smoothness texture. Higher overall liking averages were associated with the dominant attributes of chocolate with a higher level of cacao and milk coffee decaffeinated. The obtained results of the present work suggest that the multiple-intake TDS technique can be applied for the evaluation of different food categories, helping to develop healthier products and predicting the liking.

Sensory product characterisations based on check-all-that-apply questions: Further insights on how the static (CATA) and dynamic (TCATA) approaches perform

Check-all-that-apply (CATA) questions have become one of the most popular methods for sensory characterisation with consumers. Temporal CATA (TCATA) is an extension of the former that takes into account the dynamic nature of sensory perception. The aim of the present work was to expand the methodological comparison of CATA and TCATA questions, considering the characterisation of solid products that undergo substantial oral processing when consumed. Five studies involving a total of 731 consumers were conducted with different product categories: dried apricots, peas, cheese, bread and milk chocolate. A between-subjects experimental design was used to compare the static and dynamic versions of CATA questions. For comparison purposes, TCATA data were analysed as CATA by collapsing the data into four fixed time intervals (quarters). The four quarters of TCATA were compared to results from CATA considering the frequency of use of the terms, sample discrimination, and product configurations. The temporal aspect of TCATA did not largely modify the average citation proportion of terms or the maximum citation proportion for individual terms. Significant differences among samples were established for most of the terms in both CATA and TCATA evaluations, albeit some subtle differences between the two methods were found. These differences were dependent on the product category and the specific sensory characteristics that were relevant for describing the focal samples. The largest differences were found for Study 5 (milk chocolate), for which TCATA identified a few additional insights on the evolution of similarities and differences among samples. However, in most cases general findings were virtually identical for both methodological approaches. In light of these results, the extra effort of using a dynamic sensory characterisation method compared to a static one, may, in many instances, not be warranted.

Sensory characterization of cucumbers pickled with verjuice as novel acidifying agent

Verjuice is an acidic unfermented unripe grape juice that has recently been proposed as an alternative to vinegar in different food preparations. In this study, pickled cucumber preserves were industrially prepared using two dilutions of verjuice as acidifying agent and compared with the traditional vinegar-pickled samples. Samples were chemically characterized and subjected to sensory analyses using a trained panel and consumers. The different acidifying agents resulted in pickled cucumbers giving different olfactory and gustatory evaluations. No differences in appearance and texture were found. Despite showing chemical and sensory differences, pickles preserved with verjuice and vinegar had similar overall liking scores for visual, olfactory and gustatory aspects. A key feature of pickles prepared with verjuice is their lack of acetic acid potentially conferring them an additional value, suggesting that verjuice represents a viable alternative to vinegar for the production of pickles with distinctive sensorial properties.

Neural Correlates of Preference: A Transmodal Validation Study

Liking is one of the most important psychological processes associated with the reward system, being involved in affective processing and pleasure/displeasure encoding. Currently, there is no consensus regarding the combination of physiological indicators which best predict liking, especially when applied to dynamic stimuli such as videos. There is a lack of a standard methodology to assess likeability over time and therefore in assessing narrative and semantic aspects of the stimulus. We developed a time-dependent method to evaluate the physiological correlates of likeability for three different thematic categories, namely: adventure (AV), comedy (CM), and nature landscape (LS). Twenty-eight healthy adults with ages ranging from 18 to 35 years (average: 23.85 years) were enrolled in the study. The participants were asked to provide likeability ratings for videos as they watched them, using a response box. Three 60-s videos were presented, one for each category, in randomized order while the participant’s physiological data [electroencephalogram (EEG), electrocardiogram (ECG) and eye tracking (ET)] was recorded. The comedy video (CM) presented the smallest minimum accumulated normalized rating (ANR; p = 0.013) and the LS video presented the highest maximum ANR (p = 0.039). The LS video presented the longest time for first response (p < 0.001) and the AV video presented the shortest time for maximum response (p = 0.016). The LS video had the highest mean likeability rating with 1.43 ± 2.31 points; and the CM video had the lowest with 0.57 ± 1.77. Multiple linear regression models were created to predict the likeability of each video using the following physiological indicators; AV: power in beta band at C4 and P4 (p = 0.004, adj. R² = 0.301); CM: alpha power in Fp2 (p = 0.001, adj. R² = 0.326) and LS: alpha power in P4, F8, and Fp2; beta power in C4 and P4 and pupil size, (p = 0.002, adj. R² = 0.489). Despite its limitations (e.g., using one 1-min video per category) our findings suggest that there is a considerable difference in the psychophysiological correlates of stimuli with different contextual properties and that the use of time-dependent methods to assess videos should be considered as best practices.

Multi-Sip Time⁻Intensity Evaluation of Retronasal Aroma after Swallowing Oolong Tea Beverage

In most cases, a meal cannot be finished with a single bite and sip. During eating and drinking, consumers receive dynamic food perceptions from sensory attributes in foods. Thus, we performed multi-sip time–intensity (TI) evaluation of sensory attribute. In each of ten trials, the participant evaluated continuously the intensity of retronasal aroma for 60 s after swallowing oolong tea. We compared the TI parameters (I_max: maximum intensity, T_max: time point at which intensity reached the maximum value, AUC: area under the TI curve, D_plateau: duration between the first and last time points with values exceeding 90% of the maximum intensity, R_inc: rate of intensity increase between the first time points with values exceeding 5% and 90% of the maximum intensity, and R_dec: rate of intensity decrease between the last time points with values exceeding 5% and 90% of the maximum intensity) and TI curves among the ten trials, and approximated each TI curve with an exponential model. Some TI parameters (I_max, T_max, AUC, and R_inc) differed significantly between the first and subsequent trials. The TI curve was significantly lower in the first trial than in the subsequent trials, and TI curve during the time from starting the evaluation to reaching maximum intensity was significantly lower in the second trial than in the subsequent trials. The time constant of the fitted exponential function revealed that the decay of retronasal aroma intensity was slightly faster in the second through fourth trials than in the first and the fifth through tenth trials. These results indicate that olfaction might be more perceptive while consumers sip a cup of the beverage.

Appearance alteration of fruits and vegetables to increase their appeal to and consumption by school-age children: A pilot study

Picky eating with regard to fruit and vegetables is common among children. This study investigated the effectiveness of enhancing the visual appeal of fruit and vegetables to increase children’s liking and consumption of fruit and vegetables. A pre–post experimental design was used, and the control and experimental groups were repeatedly exposed to the original food and transformed food, respectively, over 6 weeks. Significant differences in the consumption of pumpkin, sweet potato, spinach, carrot and aubergine were observed between the groups, demonstrating that the appearance appeal of fruit and vegetables improves the willingness of children to try disliked fruit and vegetables and increases their vegetable consumption.

Methods for Evaluating Emotions Evoked by Food Experiences: A Literature Review

Besides sensory characteristics of food, food-evoked emotion is a crucial factor in predicting consumer's food preference and therefore in developing new products. Many measures have been developed to assess food-evoked emotions. The aim of this literature review is (i) to give an exhaustive overview of measures used in current research and (ii) to categorize these methods along measurement level (physiological, behavioral, and cognitive) and emotional processing level (unconscious sensory, perceptual/early cognitive, and conscious/decision making) level. This 3 × 3 categorization may help researchers to compile a set of complementary measures (“toolbox”) for their studies. We included 101 peer-reviewed articles that evaluate consumer's emotions and were published between 1997 and 2016, providing us with 59 different measures. More than 60% of these measures are based on self-reported, subjective ratings and questionnaires (cognitive measurement level) and assess the conscious/decision-making level of emotional processing. This multitude of measures and their overrepresentation in a single category hinders the comparison of results across studies and building a complete multi-faceted picture of food-evoked emotions. We recommend (1) to use widely applied, validated measures only, (2) to refrain from using (highly correlated) measures from the same category but use measures from different categories instead, preferably covering all three emotional processing levels, and (3) to acquire and share simultaneously collected physiological, behavioral, and cognitive datasets to improve the predictive power of food choice and other models.

The impact of yeast starter cultures on the microbial communities and volatile compounds in cocoa fermentation and the resulting sensory attributes of chocolate

Theobroma cacao seeds are the main raw material for chocolate production. During their fermentation, a succession of microorganisms are responsible for the physicochemical changes occurring in the pulp and inside the beans. The aim of this study was to investigate the effects of yeast inoculation (Saccharomyces cerevisiae UFLA CA11, Pichia kluivery CCMA0237, and Hanseniaspora uvarum CCMA0236) on the profile of the volatile compounds and microbial communities in cocoa fermentation. The resulting chocolate was also evaluated by temporal dominance of sensations (TDS) analyses. The dominant microorganisms during spontaneous fermentation were S. cerevisiae, H. uvarum, H. guilliermondii, Lactobacillus fermentum, Pediococcus sp., and Acetobacter pasteurianus. Similarly, S. cerevisiae, P. kluyveri, Candida sp., Pediococcus sp., and A. pasteurianus were the predominant microorganisms assessed by Denaturing Gradient Gel Electrophoresis (DGGE) in inoculated fermentation. Sixty-seven volatile compounds were detected and quantified by gas chromatography/mass spectrometry (GC/MS) at the end of fermentation and chocolates. The main group of volatile compound found after the inoculated and spontaneous fermentations was esters (41 and 39 %, respectively). In the chocolates, the main group was acids (73 and 44 % from the inoculated and spontaneous fermentations, respectively). The TDS analyses showed a dominance of bitter and cocoa attributes in both chocolates. However, in the inoculated chocolate, lingering fruity notes were more intense, while the chocolate produced by spontaneous fermentation was more astringent. Thus, the inoculation of yeast influenced the microbial profile, which likely affected the volatile compounds that affect sensory characteristics, resulting in chocolate with dominant bitter, cocoa, and fruity attributes.

Evaluation of visual and taste preferences of some gluten-free commercial products in a group of celiac children

The purpose of this study was to investigate the visual and taste liking of three commercial gluten-free (GF) foods in a group of celiac children. Thirty celiac children, with diagnosis of celiac disease from more than 2 years, were recruited and 28 (21 females and 7 males, mean age 8.7 years) completed the study. Subjects performed individually six sensory tests, two for each product in different days separated by a week. In the test day, children had to evaluate the liking of the same type of product but of different four brands, before and after tasting them with a 5-point facial rating scale. Overall, the results showed that the majority of children appreciated more the appearance than the taste of all the GF products analysed. The present study provides the first and useful indications on the hedonic perceptions of celiac children about some commercial GF products.