Memory of sweetness and fatty flavours: Effects of gender and liking

Memory plays a major role in determining people’s expectations and choices of foods. In an experiment we investigated how well young people remember sweetness and fattiness under natural conditions, where they had not been instructed to remember anything about the stimuli when they were first encountered (incidental learning). In order to be able to compare memory of fattiness and sweetness, we also determined perceptual discriminability between the targets and distracters used in the experiment. A full account of the experiment is provided in Hausner and Møller (2006).

Experiment

Food choice and food behaviour in general depend on appropriateness, expectations and preferences. What is appropriate and which expectations and preferences we entertain rely on previous encounters with foods and memory for foods thus play an important role in determining food choice. In light of the serious problems of overweight in many parts of the world, it is important to better understand the relationships between sensory and nutritional properties of foods (Sørensen, Møller, Flint, Martens, & Raben, 2003).In the experiment we investigated how well young people remember sweetness and fattiness under natural conditions, i.e. conditions where they had not been instructed to remember anything about the stimuli (a milk based rice product, MiniMeal, ARLA Foods Ltd.) when it was first presented to the subjects (incidental learning). In previous work (Møller et al., 2004 and Møller et al., submitted for publication) we have demonstrated that memories of incidentally learned smells, tastes and flavours are stored differently than stimuli stored intentionally. In this experiment it was crucial to make sure that subjects build up their memories in an incidental way, which is exactly how memories for food behaviour develop as a result of our every-day dealings with foods.Subjects in the experiment arrived in the laboratory at 8 a.m. after having fasted for 12 h. They were exposed to the stimulus to be remembered (the ‘target’) via participation in another experiment in which male/female subjects ate 10 portions of 50/40 g of the target. Subjects scored liking, wanting (to eat more of the target) as well as feelings of hunger and satiety during this phase of the experiment. They returned to the laboratory 3 h later and it was only at this time it was revealed to them that we would measure how well they remembered the target they had eaten previously. To evaluate memory of the target we had prepared 3 sweeter versions (S1, S2 and S3) and three more fat versions (F1, F2 and F3) of the product we used as target. These distracters were then presented to the subjects in a random sequence of an equal number of sweet distracters, fatty distracters and targets. On the basis of the number of hits and false alarms we calculated d-prime values for recognition. In order to be able to compare memory of fattiness and sweetness, we also determined perceptual discriminability between the targets and distracters used in the experiment.In this experiment we were particularly interested in the following questions:How well do we remember sweet and fat foods after incidental (ecologically interesting) learning?Both men and women remember fattiness better than sweetness. The womens’ d-prime values for both sweetness and fattiness are larger than they are for men. This result does not occur because women discriminate the target better from the distracters than men do. We found no difference in discriminability between men and women.Does memory for sweetness and fattiness depend on liking?Dividing subjects into likers and non-likers of the stimuli (fat and sweet distracters) at the median (same number of subjects in the two groups) we find that non-likers have much better memories for sweetness and fattiness than likers.Is memory for sweetness and fattiness veridical?Interestingly, we find negative memory d-prime values for sweetness for men in the liking group. This means that subjects score more false alarms than hits. Since all our distracters were sweeter than the target, this means that men who like the (sweet) food we used in the experiment remember the food as more sweet than it was.Is memory based on remembering previous encounters of a stimulus or does it rather serve to detect deviant stimuli (“novelty detection”)?Operationally, remembering requires that memory d-prime values are significantly different from zero. Scoring a large number of hits (‘Reply yes when you are presented with the target in the test phase of the experiment.’) or a low number of false alarms (‘Reply no when you are presented with a distracter in the test phase of the experiment.’) will produce d-prime values different from zero. In this experiment we find that both men and women have difficulty ‘recognizing’ the target. The number of hits and misses are about the same. On the other hand, the correct rejection rate is large corresponding to a low false alarm rate. Memory for sweetness and fattiness is thus based on correctly rejecting new stimuli (the distracters) subjects have not encountered previously.

Summary

We have found evidence that there are gender differences with respect to memory for sweetness and fattiness. Women have better memories for both sweetness and fattiness than men. Hedonicity also influences how well we remember these stimuli. Non-likers have much better memories than likers, with the notable exception of women in the case of fattiness. Female likers of fat stimuli remember the stimuli as well as female non-likers.It is interesting to note that likers of sweetness tend to remember the stimuli as more sweet than they were. This might be a contributing factor in the generation of craving for sweet foods.The results of this experiment are in line with other recent experiments by Köster et al., 2004, Mojet and Köster, 2002, Mojet and Köster, 2005, Møller et al., 2004 and Møller et al., submitted for publication. Investigating memory for smell, taste, flavour and texture, these authors consistently find that memory in the “lower senses” is tuned to “novelty detection”, rather than remembering the precise attributes of the target they are asked to pick out among a set of different stimuli (distracters).     

Changes in perception and liking for everyday food odors among older adults

The age-related decline in olfactory function is well established and concerns intensity perception and odor identification. However, the extent to which olfactory decline influences food preferences is less clear. Furthermore, it is unclear whether there are decline patterns relating to food odors, specifically. This study investigated intensity perception and hedonic liking for 14 multi-component food odors and one pure odorant in three groups of older adults (age 60–69, age 70–70, age 80 + ) and a group of young adults. In total 335 subjects were tested, 246 old and very old adults and 89 young adults. The age group 60–69 was on par with the young adults, whereas intensity perception declined for the majority of odors for older adults age 70–79 and the very old age 80 + . The largest drop in intensity perception was seen for savory odors; fried meat, mushroom and onion. In contrast, intensity perception for raspberry and orange did not differ between groups of older adults and young adults. Hedonic liking decreased to some degree with increasing age but remained largely the same for savory odors (bacon, mushroom, fried meat and onion). A decline in liking was seen for coffee and thyme. This study shows evidence that age-related decline in intensity perception is food odor specific and some aggregation may occur at a higher concept level for the “savory” category. Furthermore, hedonic liking is not necessarily dependent on the intensity perception as seen for several odors, where declining intensity perception did not impact hedonic liking. This could be explained by changes in dose-response relationships for the group of ageing individuals, which in fact may favor persistence of the food odor liking, despite a decline in their intensity perception.     

Extrinsic attributes responsible for red wine quality perception: A cross-cultural study between France and Spain

Understanding quality perception requires focusing both on product proprieties and consumers’ representations. The goal of this study was to access the representations of perceived extrinsic wine quality of consumers from two different wine regions in two European countries with an important wine tradition: La Rioja-RJ-(Spain) and Côtes du Rhône-CdR-(France).Twenty commercial red wines (ten from RJ and ten from CdR) were evaluated in terms of quality by means of a categorization task. Ninety-five French and 93 Spanish consumers had to categorize the 20 wines according to four levels of quality going from very low to very high quality.Three clusters of French and two of Spanish consumers have been identified. Country-of-origin of wine arises as the most important extrinsic cue for less-involved French and Spanish consumers, while more-involved consumers with higher knowledge in wine are able to interpret and use a wider range of cues. Consumers’ knowledge, involvement and nationality appear to be good predictors of quality perception.These results are relevant for the field of sensory analysis in that they help understanding the construction of quality perception. The wine industry can benefit also from these results, especially when exporting wines. This cross-cultural study may help them to develop marketing strategies able to enhance the quality perception of wines and to make use of different extrinsic factors.     

Measuring eating capability,liking and difficulty perception of older adults: A textural consideration

Malnutrition in older adults is partly attributable to decreasing muscle strength leading to inadequate intakes. It is therefore important to investigate ways of identifying eating capability both through objective measures of strength and subjective measures of perceived difficulty and liking. In addition, food texture design might affect the oral processing and the difficulty perceived. Therefore the present study sets out to examine the relationship between various quantitative measures of eating capability (EC) and perceived difficulty of processing foods and gels varying in hardness in older adults. Tests were conducted on 30 participants (mean age 79 ± 9.4 years) using non-invasive techniques (hand gripping force, tongue pressure, biting force, and hand dexterity) in conjunction with frame-by-frame video recording analysis of chewing and swallowing of food stimuli and ratings of eating difficulty. The EC scores were computed to grade the population into three different groups. Stimuli were classified into two categories: food products and flavourless hydrocolloid gels with different inhomogeneity (textures). The EC parameters did not correspond to oral residence time, or the difficulty perceived. Bite force differed by EC group, and was significantly different by dental status [F(3,4.26) = 3.842, p = 0.022], and influenced both liking and number of chews. The food hardness (r = 0.915, p = 0.01) was significantly correlated with the number of chews. Gel heterogeneity influenced food oral processing behaviour. Oral residence time was significantly correlated with number of chews, liking and difficulty perceived. In summary, dental status and bite force of older adults are determining EC parameters to design optimized food-texture.     

Consumers’ perception of symbols and health claims as health-related label messages. A cross-cultural study

The package is the first contact between the food and the consumer and an excellent vehicle for communication with the consumer. Visual cues (symbols) on the package can be used to communicate health-related information. Although EU legislation provides for the use of symbols, there could be a still undiscovered or unquantified gap between the consumers’ perception of some symbols and how much these symbols appeal and convince. The objective of this research was to study the perception of symbols and their relative importance, combined with verbal health claims, in perceptions of the product’s appeal and convincingness in two countries, one Mediterranean (Spain) and the other Scandinavian (Denmark). Four symbols were employed in the study: (1) heart-plus-stethoscope, (2) olives (a symbol often used in Spain but not so much in Denmark), and two not directly linked to food products: (3) active person (a person running towards the sun), and (4) gears. Perceptions of these symbols were studied through word association, free listing and conjoint analysis. Three verbal health claims were presented as either benefits or risks in combination with the images. The results showed that the overall idea of the symbols perceived by the participants was similar in both countries but the culture influenced the connotations attached to the symbols. In addition, the symbols on the packaging were found to be more important than the verbal information.     

Genetics,odor perception and food liking: The intriguing role of cinnamon

Humans use a repertoire of > 400 olfactory receptors (ORs) to perceive odorants. The sense of smell is a complex trait whereby genetics and environmental factors interplay. To date, still little is known regarding the genetics of smell, even though the high genetic variability of ORs genes has already been demonstrated. Recently a significant association between cinnamon odorant recognition and the rs317787 polymorphism, located in a cluster of OR genes, has been described. Based on this data, here, we replicated the effect of the same variant (rs317787) on cinnamon odorant identification as well as looked at any possible association with liking for wine whose bouquet frequently smells of cinnamon. Our analysis in a cohort of individuals from two Italian genetic isolates confirmed that rs317787-T allele is associated with an improved cinnamon detection (p-value 5.18 × 10⁻⁰⁶, n = 971) but also with a greater liking for red wine (p-value 0.017, n = 2374). Present results further confirm the association of rs31778 SNP and cinnamon odorants detection and provide additional details about the role of the ORs genes in food liking. Overall, our work contributes to better deciphering the genetic basis of smell and food liking aimed at a more in-depth elucidation of the role of the ORs genes.     

Consumer perception and liking,and sensory characteristics of blended teas

Food Science and Biotechnology - This study was conducted to identify the sensory characteristics of six blended teas containing different ingredients and analyze penalty factors for the products...     

Effect of gel texture and sucrose spatial distribution on sweetness perception

Layered gels differing in mechanical and breakdown properties (soft, medium and hard gels) and in the distribution of sucrose in the matrix (homogeneous and inhomogeneous distributions) were used to investigate the effects of texture and spatial distribution of sucrose on sweetness perception. Rating tests, 2-Alternative forced choice tests and time-intensity analysis were performed to compare the sweetness of soft, medium and hard gels with homogeneous and inhomogeneous distributions of sucrose. Results showed that all gels with an inhomogeneous distribution of sucrose were perceived sweeter than gels in which sucrose was homogeneously distributed. This indicates that the enhancement of sweetness by an inhomogeneous distribution of sucrose does not depend on the texture of the gel matrix. Furthermore, the time-intensity profiling showed that soft gels, which had low values of fracture strain and fracture stress and broke down in a large number of small fragments upon chewing, had the highest sweetness intensity. The time required to reach the maximum sweetness intensity tended to be shorter in soft gels. These findings suggest that the breakdown behavior of the gel matrix during oral processing affects the perception of sweetness of layered gels.     

Influence of texture on the temporal perception of sweetness of gelled systems

The aim of this work was to study how the texture of two hydrocolloid gelled systems with different mechanical properties – κ-carrageenan and gellan gum – sweetened with two sweeteners with different sweetening power – sucrose and aspartame – influence the temporal perception of sweetness using a time–intensity test. The results show that the different aspects of temporal perception of sweetness of hydrocolloid gels were related to their mechanical properties in different ways. Maximum sweetness intensity was closely related to the amount of deformation required to break the network and with its resistance to deformation. Meanwhile resistance to rupture was also an important factor influencing the variation in the rate of intensity decrease. The time needed to reach maximum sweetness intensity was only dependent on sweetener concentration.     

Sweetness intensity perception and pleasantness ratings of sucrose, aspartame solutions and cola among multi-ethnic Malaysian subjects

As the sugar intake of Malaysians is one of the highest in the Asia Pacific region, we wanted to investigate how this high prevalence of ‘sweet tooth’ is influenced by biological determinants like age, gender, ethnicity and Body Mass Index (BMI). This study therefore sought to use the generalized Labeled Magnitude Scale to evaluate the sweetness intensity perception and pleasantness ratings of not only three increasing suprathreshold concentrations of sucrose and a popular naturally-sweetened carbonated beverage - Coca-Cola®, but also their non-nutritive sweetener (NNS) counterparts - aspartame and Coca-Cola Light®. Taken together, the overall intensity of NNS solutions and beverage was perceived as significantly higher, but not for their pleasantness. The intensity perception and pleasantness of most sweet solutions were not significantly associated with gender and BMI. Overall, Malays had a lower perceived intensity of sweet stimuli compared to other ethnicities, but a conclusion of the influence of ethnicity on sweetness pleasantness could not be met. Lastly, sweetness intensity perception and pleasantness ratings for both colas decreased significantly with age.     

Influence of colour intensity on the perception of colour and sweetness in various fruit-flavoured yoghurts

A study was made of the influence of colour concentration on the perception of flavour, sweetness and colour intensity, and also of opinions about colour suitability, in yoghurts with strawberry, lemon, fruit of the forest and orange flavours. The results indicated that, even with the same content of each fruit flavour and sugar, the greater the concentration of colourant, the greater was the intensity of taste perceived by the assessors in yoghurts with strawberry, orange and fruit of the forest flavours. With regard to perception of sweetness, only in the yoghurts with fruit of the forest flavour was it found that the greater the concentration of colourant, the greater was the sensation of sweetness.In the range of colourant concentrations studied for the four flavours, it was found that the colour considered most suitable corresponded to the yoghurts with intermediate colourant concentrations and that, for the four flavours studied, the greater the concentration of colourant, the greater was the sensation of intensity of colour.     

Children’s liking and intake of vegetables: A school-based intervention study

This study investigated effects on vegetable liking and intake gained from exposing children to snack vegetables of different liking levels. In total, 345 9–11-year-old children participated. The intervention consisted of two exposure periods. First, children were either exposed to a neutrally liked vegetable (cauliflower), a mixture of a neutrally liked and a liked (sugar snap peas) vegetable, or a mixture of a neutrally liked and a disliked (celery) vegetable. In the second, period all children were served all vegetables. Intake of individual vegetables was measured daily. Liking was assessed before and after exposures and at a subsequent follow-up. Liking for most vegetables decreased during the exposure periods but tended to recover somewhat during follow-up. Intake of all vegetables was either stable or decreased during the intervention, no increases were observed. Intake levels depended on type of vegetable servings: When served with a liked vegetable, children consumed more of a neutrally liked vegetable than when served alone (p = 0.0005) or together with a disliked vegetable (p = 0.005).     

Personality traits and bitterness perception influence the liking and intake of pale ale style beers

Bitterness is classically considered undesirable in foods and beverages. Yet, widespread commercial success of beers (like Bitters in the UK or IPAs in the US) indicate bitterness is desirable for some consumers. Here, we tested whether personality traits influence beer liking and intake. Under laboratory conditions, beer consumers (n = 109) rated liking and intensity of 2 pale ales and a lager, and intensity of two bitter solutions (quinine, Tetralone®). Participants also completed intake and personality questionnaires (Sensation Seeking, Sensitivity to Punishment and Reward, and Food Involvement). A liking ratio for each beer was calculated from each participant’s liking for that specific beer and their total liking for all beers. Participants were classified as weekly, monthly, or yearly pale ale consumers using intake data. Using intensity ratings, personality measures, and other parameters, hierarchical linear regression was used to predict liking ratios, and logistic regression was used to predict beer intake frequency. A significant interaction between Sensation Seeking and quinine bitterness (p = 0.03) was found for the liking ratio of a pale ale. The interaction revealed liking of the pale ale increased with Sensation Seeking but only if quinine bitterness was also high. Intake models showed increased odds of frequent pale ale intake with greater quinine bitterness and lower liking for lager beer. These data suggest liking and intake of pale ales is positively related to Sensation Seeking and bitter taste perception. Contrary to findings in other bitter foods and beverages, the high bitterness found in pale ales may be desirable for some consumers.