Temporal dominance of emotions: Measuring dynamics of food-related emotions during consumption

Mapping food-evoked emotions in addition to sensory profiling is topical. In sensory profiling, the Temporal Dominance of Sensation (TDS) method focuses on the assessment of the temporal evolution of dominant sensory attributes over time. We hypothesize that food-evoked emotions also show temporal dynamics that can be related to dynamic sensory perception. This study assessed temporal dynamics of sensory and emotional attributes during chocolate tasting. We used TDS to determine dynamic sensory properties of dark chocolates providing a list of 10 sensory attributes. Comparably, Temporal Dominance of Emotions (TDE) was assessed by replacing the sensory attributes with 10 emotional attributes. Sixty-two participants assessed TDS and TDE of five commercially available dark chocolates (plain and flavoured). Multivariate comparisons (Hotelling test) showed significant differences between products based on the dominance duration of sensory (p < 0.05) and emotional attributes (p < 0.05). TDS difference curves revealed products to differ based on their dominant sensory attributes, with different attributes peaking at different time moments. TDE difference curves showed that products also differed in the temporal distribution of dominant emotional attributes. Comparing the average dominance rates between plain dark and flavoured dark chocolates revealed that for flavoured dark chocolates mainly flavour attributes and positive/active emotions were perceived as salient whereas for plain dark chocolates textural as well as taste attributes were dominant accompanied by more negative/non-energetic emotions. A joint CVA plot on the duration of dominance for sensory and emotional attributes per product revealed that temporal evolution of sensory – and emotional attributes was related. This suggests a mutual reciprocity between those two entities (sensory and emotional attributes) resulting in more complex, richer product characterization. In conclusion, these findings show TDE to be a promising new venue in characterising food-evoked emotions in relation to sensory profiling.     

Dynamic texture perception in plant-based yogurt alternatives: Identifying temporal drivers of liking by TDS

As texture properties in novel food categories have a crucial role in consumer acceptance, mouthfeel profile of different plant-based yogurt-like semi-solid products were studied and compared to dairy yogurts. Mouthfeel properties of five plant-based yogurt-like products and two dairy yogurts were analyzed using temporal dominance of sensations (TDS) with consumers (n = 87). The attributes evaluated were thick, thin, creamy, watery, sticky, and foamy. Following TDS, overall liking and mouthfeel liking were evaluated using a 7-point hedonic scale. Temporal drivers of mouthfeel liking were studied using correspondence analysis and penalty-lift analysis with different time points during mastication. For penalty-lift analysis TDS data was analyzed as check-all-that-apply (CATA) data. Results from the present work show that mouthfeel perception in non-dairy yogurt alternatives is a dynamic process. Attributes typically used to describe dairy yogurts are also relevant for describing non-dairy yogurt alternatives. Yogurt alternatives and dairy yogurts can be similar and equally liked by their mouthfeel profile. Temporal drivers of liking in plant-based products are thickness and creaminess and temporal drivers of disliking are thinness and wateriness. In this study, the first dominant attributes were found to have a stronger impact on mouthfeel liking than the dominant attributes perceived later during mastication.     

Visualization of temporal differences between dominant perceptions in temporal dominance of sensations (TDS) and temporal check-all-that-apply (TCATA) perceptions using dominance-highlighted TCATA (dTCATA) curves

The temporal dominance of sensations (TDS) method measures dynamic changes of panelists’ attention to the sensory attributes of products. The temporal check-all-that-apply (TCATA) method measures all sensory attributes perceived at each moment of an evaluation. However, unlike in TDS, significant levels cannot be calculated in TCATA. This study proposes the use of dominance-highlighted TCATA (dTCATA) curves, which are highlighted TCATA curves that show significant time periods for the TDS data of different panels. Twelve R&D panelists evaluated five commercial corn soups using the TCATA method. Then, 125 consumer panelists evaluated the same products using the TDS method. The dTCATA curves showed TCATA curves for all attributes for each product evaluated by the R&D panel highlighted with the dominance rates identified by the consumer panel in the TDS evaluation. For example, for product 1, some attributes (sweet, viscosity) showed relatively high citation proportions in the TCATA evaluations of the R&D panel and significant dominance rates in the TDS evaluations of the consumer panel. In contrast, consommé flavor showed relatively low citation proportions in TCATA but significant dominance rates in TDS. By merging TDS and TCATA data, we could compare consumers’ dominant sensations with the evaluations of R&D panelists. This comparison could provide useful insights to product developers. In some cases, we observed attributes with significant dominance rates that were under-identified by the R&D panel in TCATA. This could suggest that most of the R&D panel may not have perceived these attributes; therefore, during product development, these attributes should be carefully considered.     

Alternative protein sources in Western diets: Food product development and consumer acceptance of spirulina-filled pasta

Spirulina (Arthrospira platensis) is currently being increasingly researched for its usability and suitability in human nutrition. The inclusion of alternative protein sources, such as spirulina, in familiar products is a possible strategy to nudge consumers towards dietary change in Western societies. Filled pasta variants with three levels of spirulina-soy-extrudate in the filling (10%, 30% or 50%) were developed and investigated for their sensory characteristics and consumer liking. Recipe development was based on the concepts of flavor-flavor learning (beet-ginger or tomato) and masking (lemon-basil) to account for the musty and earthy notes of the alga. Consumer tests were conducted in Germany (n = 139), the Netherlands (n = 137) and France (n = 144), and conventional sensory profiling was accomplished with trained panelists (n = 12). Consumers preferred the lemon-basil flavor over tomato and beet-ginger flavored fillings. As expected, liking decreased with increased extrudate content, regardless of the flavor. For all flavors expected liking was higher than liking after product exposure; for the lemon-basil flavor the gap was the smallest. It was shown that low general food neophobia and familiarity with spirulina promoted consumer liking. The sensory profiling revealed that the spirulina-soy-extrudate content affected all sensory attributes identified across all flavors, but for the tomato flavor the most. Overall, this study confirms that it is important to consider differences in consumer motivation as well as the product’s conceptual and intrinsic sensory characteristics in new product development.     

Strategies to compensate for undesired gritty sensations in foods

This study investigated whether the addition of macroparticles or fat can be used to compensate for negative texture sensations in quark. Cellulose beads were added as model microparticles (1.5% w/w; average size: 263 µm) to quark (0% fat) to induce unpleasant gritty sensations. The addition of microparticles to quark significantly increased grittiness and dryness, while creaminess and liking decreased. Three strategies were explored to reduce the impact of unpleasant gritty sensations on consumer perception: two strategies involved the addition of macroparticles (granola or peach gel pieces); the third one consisted of increasing the fat content of the quark (4.4 and 8.8% w/w). For all three strategies, grittiness caused by microparticles did not significantly decrease when macroparticles or fat were present. Addition of peach gel pieces to quark with microparticles did not increase liking. When granola pieces were added to quark containing microparticles, liking increased significantly despite that grittiness was still perceived. Temporal Dominance of Sensations (TDS) revealed that addition of granola pieces caused prolonged dominance of positive, crunchy sensations and minimized dominance of negative, gritty sensations. The addition of fat did not lead to a significant increase in liking of quark, although when a medium amount of fat was added (4.4%), it also did not decrease liking significantly. This was probably due to an effective hedonic compensation triggered by more positive sensations (i.e. sweetness). We conclude that addition of crunchy granola pieces or fat can be used as strategies to shift and increase dominance of positive and liked attributes, leading to an increase of overall liking, although negative sensations (grittiness) caused by microparticles are still perceived. This approach could be used to compensate for undesired texture sensations in different types of foods, such as high protein foods.     

Investigating temporal sensory data via a graph theoretic approach

A graph theoretic approach is applied to investigate perception dynamics in the Sensometrics 2018 Data Analysis Workshop data sets. First, temporal check-all-that-apply (TCATA) data are investigated: ten sensory attributes are modelled as vertices and concurrent perception as edges, the size and width of each corresponding to the momentary elicitations and the concurrent elicitations, respectively. A temporal dominance of sensations (TDS) data set does not lend itself as readily to this type of analysis because the task for each assessor involves selection of only one dominant attributes at a time. For this reason, TDS data sets considered in this workshop are (re-)analyzed within localized temporal ranges, considering dominance elicitations within localized temporal ranges to be adjacent-dominant. In TDS by Modality (M-TDS), assessors taste the sample to evaluate the five taste and flavour attributes via TDS, then retaste the sample to evaluate the five texture attributes via TDS. M-TDS results from these two separate tasting timelines are adjoined as if they arose from a single evaluation timeline, which ignores systematic biases that may be introduced by the evaluation protocol (e.g. texture attributes are always evaluated with carryover effects from the first tasting). Data from each of these temporal sensory method are then analyzed using a graph theoretic approach. Cliques and attribute structures are identified. TCATA and TDS results are more similar to one another than either is to M-TDS results. Implications of method choice and various data pre-processing decisions are discussed.     

Characterization of Siahmazgi cheese,an Iranian ewe's milk variety: Assessment of physico-chemical,textural and rheological specifications during ripening

Siahmazgi cheese is an Iranian locally-made cheese produced from ewe's milk or a mixture of ewe and goat's milks in the suburbs of Rasht in the north of Iran. This kind of cheese is kept in sheepskin for six months under special condition which cause distinct physicochemical and textural characteristics. Therefore, in the present study the effect of ripening time (6 months) on the chemical, physicochemical, rheological and textural characteristics of Siahmazgi cheese (18 samples) was investigated. The rheological and textural properties were determined using rheometer (frequency sweep) and texture analyzer (uniaxial compression). Based on our findings, the measured values including pH, titratable acidity (TA), dry matter, fat, protein, ash, salt content, water soluble nitrogen in total nitrogen, and non-protein-nitrogen in total nitrogen significantly increased during ripening (P < 0.05). Furthermore, the results showed that the six-month ripened Siahmazgi cheese contained high values of dry matter (59.95 ± 0.08 g/100 g), salt (5.65 ± 0.05 g/100 g), and ash (7.24 ± 0.02 g/100 g). Regarding rheological and textural properties, storage modulus (G′), loss modulus (G″), fracture stress (σ_f) and firmness increased while loss tangent and fracture strain decreased.     

Alternating temporal dominance of sensations and liking scales during the intake of a full portion of an oral nutritional supplement

Measurement of liking with consumers is often performed on a single sip or mouthful of the product and results in a single liking score that does not necessarily reflect the liking over consumption of a whole product. A dynamic approach could provide this type of information. Thus, obtaining reasons why the liking score is changing over consumption could help to gain insights for product improvement. Recently, Thomas, Visalli, Cordelle, and Schlich (2015) suggested collecting with the same consumers liking scores dynamically and Temporal Dominance of Sensations (TDS) during mono-intakes of flavored cheeses, in two independent sessions. This new type of sensory data has been analysed at individual level to identify “temporal drivers of liking” for each product.The present paper further develops this method consisting of collecting TDS and dynamic liking data in the same session and during the consumption of the full portion of a product. The products used to experiment this new method were two commercial oral nutritional supplements (ONS) assessed by 65 consumers over two lab sessions separated by one week.The protocol consisted of a TDS evaluation of 5 flavor, 2 texture and 3 taste sensations during each sip, immediately followed by a liking scale. This protocol was repeated over sips. This method, named “Alternated Temporal Drivers of Liking” (A-TDL), required that consumers record liking changes and do TDS over sips during food consumption. Results showed that one of the two ONS was more liked than the other and consumed in a larger volume resulting in a higher energy intake. In contrast, the other product resulted in a stronger thirst and presented more negative temporal drivers of liking (dry, metallic, filming) over the consecutive sips.     

An exploratory study of sensory attributes and consumer traits underlying liking for and perceptions of freshness for ready to eat mixed salad leaves in Italy

The role of sensory attributes and storage time information in driving liking for and perceptions of freshness for ready to eat vegetables was investigated in mixed salad leaves for different storage times (0, 3, 7 and 9 days). A modified Repertory Grid Method was used to identify ten attributes describing consumer's perception of sensory properties over storage. Eighty-one consumers rated the overall liking, the intensity of sensory attributes and the level of freshness in salad samples at different storage times. Freshness was evaluated in blind and informed conditions. Furthermore, consumers filled in a Food Choice Questionnaire and rated the importance of six attributes known to be important for ready to eat salad choice. The relationships between sensory properties significantly affected by storage time, perceived freshness and liking showed that both liking and freshness were positively related to appearance attributes (green colour, salad assortment and leaf turgidity). The perceived level of freshness, expiry date and appearance were confirmed as the most important attributes for ready to eat salad choice. Two clusters of consumers (Cl1: n = 49; Cl2: n = 32) were identified based on the mean liking rating. The positive effects on health and mood as well as ethical concerns drove food choice more in Cl1 than in Cl2 subjects. No significant effect of storage time was found on liking ratings expressed by Cl1 in blind conditions, while a significant decrease of perceived freshness was observed. On the other hand, results from Cl2 in blind conditions showed a significant decrease of both liking and perceived freshness. Information about storage time significantly affected freshness ratings in Cl1 but did not influence those from Cl2.Results suggest that collection of sensory data, affective responses and information about the background of subjects is needed to fully investigate the perceptions of freshness from a consumer perspective.     

Preference mapping of salmon–sauce combinations: The influence of temporal properties

Food–food combinations are complex stimuli where the dynamic nature of sensory interactions plays an important role for perception and acceptance. The aim of this study was to investigate if TDS provides additional insight about drivers of liking compared to DA in a preference mapping context. A trained sensory panel performed DA and TDS on six different samples (combinations of salmon and culinary sauces), and sixty-one consumers rated acceptance for the same samples. In addition to TDS SCORES, this study introduces the use of extracted parameters based on dominance information from TDS; the area of dominance based on the integrated area under the dominance curves and the number of dominant sensations and blends within a specified time period. Results from preference mappings showed that the TDS approaches generally provided similar but less detailed information regarding drivers of liking and disliking compared to DA. Moreover, with the use of the extracted TDS parameters, it was possible to identify the time of dominance of certain attributes and the number of perceived sensations and blends in specific time periods as potential drivers of liking and disliking. The results also showed that TDS has a potential to provide complementary information about the dynamic nature of sensory interactions in food–food combinations compared to DA.