The consumption of sweet foods has been argued to be one of the major contributors to the current obesity epidemic. There is therefore an obvious public health need for sugar reduction, but how can the food industry overcome the dilemma between reducing sugar levels and maintaining the sweet taste that is so appealing to consumers?

Researchers from the Department of Food Science, Aarhus University, and the Department of Experimental Psychology, University of Oxford have looked into the matter as part of an extensive literature review – the first of its kind to take both intrinsic and extrinsic factors into consideration in the study of sweetness in food and beverages.

The answer lies in an understanding of our sensory perception involving not just the food itself, but also everything that surrounds our food. This calls for new ways of thinking about product development and new ways of approaching food design in the food industry.

All our senses matter

Professor Derek V. Byrne, head of the science team Food Quality Perception and Society at the Department of Food Science, Aarhus University, principal investigator of Innosweet, the research project behind the review:

- Eating and drinking are amongst the most multisensory experiences that we have. When people think about the consumption of food and drinks, the sense of taste and smell usually come to mind first. However, a growing body of research conducted over the last decade or two has increasingly demonstrated that all of our senses play a role in influencing flavor perception, he explains, and adds:

- This means that the perception of sweetness is not just a matter of the amount of sugar added to a food product. The experience of sweetness depends on a number of factors that both have to do with the product itself and with the context in which the product is consumed.

The literature divides these factors into food-intrinsic, such as product colour, aroma, texture and viscosity, and food-extrinsic sensory factors, such as visual, auditory, olfactory (relating to the sense of smell) and tactile (relating to the sense of touch) properties of product packaging, servingware, background music, ambient lighting, temperature and aroma.

- There is evidence in the literature that all of these factors have an impact our experience of sweetness. What is less clear, however, is how these different factors interact and the relative importance of intrinsic and extrinsic factors to our perception of, not to mention our behaviours towards, food and drink, Professor Derek V. Byrne says.

• Read more: Sweetness happens in the mind as much as in the mouth

A sweet combination

The literature review has focused on how the different intrinsic and extrinsic factors can be combined in order to deliver an enhanced perception of sweetness. This includes an understanding of the process of eating.

Prior to eating, when food is identified and expectations are formed, visual information is gathered together with some degree of tactile (e.g. weight, surface texture, hardness etc.), orthonasal olfactory (smell), and auditory information (e.g. sizzling, fizzing, bubbling).

Then, there is the actual eating, where additional information about the food - such as its taste, aroma, texture and temperature - is gathered.

Assistant Professor Qian Janice Wang, who is part of the science team Food Quality Perception and Society and the lead author behind the review, explains:

- Different senses are dominant in different parts of the eating process - and different brain mechanisms are involved. The available cognitive neuroscience suggests that the biggest impact on our experiences and behaviours occur, when several sensory attributes are changed at once, and when they complement one another. 

Industry implications

Changing multiple sensory stimuli to maximize the experience of sweetness is a challenge, as work on intrinsic and extrinsic factors are considered as belonging to different disciplines.

In industry, this is often reflected in the organizational structure. Research and Development (R&D), which is in charge of food-intrinsic properties, often sits far away from, and actually has little interaction with, the marketing department, who may be responsible for food-extrinsic decisions, such as those involving product packaging:

- R&D and the marketing department should work closely together in order to optimally balance product-intrinsic and extrinsic cues. Efforts are needed to create successful collaborations, but they are crucial to unleash the full potential of sweetness enhancement, Assistant Professor Qian Janice Wang says.