Low Calorie Yoghurt - The Complex Interplay of Sensory Aspects and Product Information
Sensory attributes and health-related product information are both important aspects of the consumers’ food choice. How do these dimensions influence each other? Norwegian researchers from the ESN member Nofima shed light on these questions using low calorie yoghurt as an example.
“Low-Cal”, “Lite”, “Sugar-Free”, “Low-Fat” – such labels are conspicuously placed in large colourful letters on the package. These visually prominent presentations indicate that foodstuff producers not only inform the consumers about “objective” aspects (calories, fat content etc.) of their products, but use those aspects as effective advertising points. Indeed, health-related product information can greatly increase the consumer’s interest in particular products. But what is the role they play when directly compared to sensory product qualities, and how are the two connected? Susanne Bølling Johansen from Nofima, the Norwegian Institute of Food, Fisheries and Aquaculture Research, reports that, “Previous studies show that extrinsic attributes, such as health-related product information, have a particularly important influence on first-time purchases, whereas the intrinsic sensory aspects, which can only be experienced through direct consumption, seems to be more important for the repurchase of a product.” However, the issue is not always so clear-cut. The expert refers to studies that show the differences between various product categories: e.g. information about reduced fat content improved the acceptance of a bread spread, but this did not hold true for yoghurt. And with soft drinks, information about reduced sugar content had a favourable effect on the purchasing decision only when the consumer did not have a clear preference for an alternative product.
Increased consumer interest in reduced fat and low sugar products
Because the Norwegian media has sensitised the consumer to the theme of the “detrimental health effects” of sugar in fruit or aroma-added yoghurt, the Norwegian research group was especially interested in the case of vanilla yoghurt. As a result of this media reporting, the request for reduced fat and low sugar yoghurt has increased within Norway. Nevertheless, the consumer still expects the sensory quality of the product to remain as unchanged as possible – this is a challenge for the producer.
Susanne Bølling Johansen explains that, “Our goal was to clarify how the sensory aspects and health-related product information interact in the case of calorie-reduced yoghurt. For this purpose we concentrated on the specific sensory aspects “sweetness” and “richness” on the one hand, and the corresponding health-related information regarding sugar and fat content on the other hand.” In order to ascertain how much influence the various drivers have on product choice, the research group decided on a conjoint analysis. This approach affords the possibility of recording and quantifying the interaction between the various product attributes.
A panel of sensory assessors profiled twelve varieties of combination of low-fat (0.1%, 1.5 %) and reduced-sugar (9%, 11%, 13%) vanilla yoghurt (in comparison, the most popular Norwegian yoghurts have a 4% fat and 16% sugar content). From these results, the researchers chose the four products that most clearly differed with regard to the determining sensory characteristics for the test.
Test among health-conscious consumers
For the consumer test, the researchers chose consumers who were particularly health-conscious and who preferred buying reduced-calorie products over normal products. The first test was a blind test in which the participants tasted the four yoghurt variations. They were given no additional information, and rated the yoghurts on a nine point scale with end-points “Like Extremely” and “Dislike Extremely”.
A week later the test subjects took part in a conjoint test. They were given a total of eight yoghurt samples, and were told that the test involved eight calorie-reduced yoghurts containing various levels of sugar and fat. The subjects were also told that, because of the slightly different production processes, it was possible that the yoghurts could vary in taste. Every sample was accompanied by two pie charts on which either true or false information as to the amount of sugar and fat reduction was represented, in comparison to the 4% fat content and 16% sugar content of the “standard Norwegian yoghurt”. Two questions were to be answered using the nine-point scale:
1. How much do you like the yoghurt? 2. How likely is it that you would buy this yoghurt when the price was acceptable?
- In the blind test, the sweetest yoghurts received the most positive ratings. With the less sweet yoghurts in the blind test, richness had a slightly negative effect, whereas with the sweeter samples, richness had a positive effect on the rating.
- In the conjoint test with supplementary information about fat and sugar content, three out of the four sample yoghurts had more positive overall ratings than in the blind test. Only for the yoghurt with the highest sugar and fat content were the ratings more favourable in the blind test.
- In every case when the information was provided, the yoghurts were rated more positively when less sugar was specified.
- Likewise when the information was provided,a richer consistency led to a lower hedonic rating only in the less-sweet samples. Information concerning higher sugar content also led to lower hedonic ratings.
- Information concerning fat content had no effect.
- The perceived sweetness also had a strong positive influence on the probability of purchase. Nevertheless, information indicating high sugar content significantly lowered the probability of purchase.
Susanne Bølling Johansen comments about the results; „In the case of yoghurt, the consumers did react to the information about sugar content, but this was independent of the perceived sweetness level. Although the sweeter yoghurts were clearly preferred, information concerning high sugar content had a significant negative effect on purchase probability.” On the other hand, information concerning fat content had no influence on the consumer. The researcher speculates that, “This could be because yoghurt – in contrast to cheese, where low fat information has been shown to have an effect – was already considered to be a low-fat and healthy product.” She concludes that, „Our study confirms the importance of sensory properties, especially sweetness, in the consumers' acceptance of yoghurt. Nutritional information was shown to play a certain role, and it appeared that this effect was independent of the strength of the sensory attributes.“