Overcoming sensory challenges when designing specialised products

With an ageing population, a higher prevalence of chronic diseases is expected worldwide. In turn, specialised segments of the population who have unique nutritional needs will only continue to grow. Bringing novel products to market for these patients presents a unique challenge for both the product developer and the sensory scientist, according to Dr Dolores Oreskovich, head of global consumer sensory insights at Nestlé Health Science.

A question of taste: Flavour perceptions in chronic disease

Food is consumed when it is appealing; nutritious food must be made to taste good if people are to be enticed to eat it.

“People with chronic conditions such as coeliac disease and kidney disease are not any different – and food choices and overall dietary patterns play a key role in improving the patient's health,” Oreskovich told the IFT FIRST Annual Event and Expo. “Following a dietary pattern in the context of a chronic condition is therefore particularly important.”

Only about half of people across diverse long-term health conditions stick to their dietary advice. The consequences include reduced clinical benefit, avoidable morbidity and mortality, and increased waste in healthcare spending. Products that taste good can ensure better compliance. However, people with chronic diseases can suffer from significant taste alterations.

For example, CKD patients experience a particular impairment in their perception of sour, salty, and umami, and develop a greater sensitivity in perception of salty and bitter tastes due to their modified sodium intake.

In oncology, multiple factors contribute to deterioration of tasting capacity; chemotherapy and radiation have an effect, but changes also occur simply because of the presence of cancer.

In dysphasia, a condition that refers to difficulty swallowing solids or liquids, patients lose their ability to eat normally. They are recommended soft-textured foods or thickened drinks for safe swallowing, and may even have to resort to tube feeding due to malnutrition.

There is a low incidence in reaching these groups, as these conditions are underdiagnosed. However, these groups have specific nutritional needs and often suffer from comorbidities, meaning there is an even more pressing need to try.

Nutritious ingredients present sensory challenges

Many ingredients with nutritional value present sensory challenges. Dairy products are a key source of protein, but do not always taste pleasant and have significant off-flavours.

Products for enteral tube nutrition take the form of specialised formulas that include hydrolysed proteins and/or amino acid formulas; however, bitterness is high among these products and off-flavours common. Vitamins are crucial to their nutrition profile but range from being tasteless and sweet to being extremely sour, bitter, stale, burning, pungent, tingling, metallic, or repulsive.

Minerals are usually provided as mineral salts. These can vary in character and intensity but are often characterised as salt, sour, bitter, metallic, astringent, and savoury.

Polyunsaturated fatty acids and amino acids are critical to health but are not pleasant to taste. For example, omega-3 and omega-6 products are usually derived from sources from fish oil, and carry residual flavours.

Fatty acids are not perceived as fatty but are considered irritants; they can vary in intensity and character while amino acids are critical to protein formation but can also vary, including sweet, salty, sour, bitter, sulphurous, and savoury.

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Case study: Co-producing a product with cancer patients

Oreskovich outlined a case study wherein a nutritional product was developed for oncology patients.

“No ideal supplement is currently available with sensory profiles specifically designed by cancer patients for cancer patients undergoing treatment,” she said. “Healthcare professionals defer to use standard nutritional beverages, which are typically overly sweet flavoured and of a milky format.”

The methodology started with understanding the patient journey. Patients (n=80) participated in 90-minute interviews providing insight on their nutritional needs, eating challenges, and food preferences. Healthcare practitioners (n=175) and caregivers (n=44) were also interviewed. Participants were questioned on taste and textural expectations.

The second phase of research focused on product development and refinement.

The qualitative findings were that patients were “looking for relief from the small indignities and discomforts that remind them that they are sick”, Oreskovich explained.

“Addressing the little things, this beverage could help the patient deal with cancer and its treatment and more effectively, both physically and mentally,” she added.

The last stage of research – product prototype screening and refinement – found that patients want a short list of recognisable ingredients that deliver nutritional benefits, and that flavour was more important than fortification.

Emotional benefits contribute to improved patient compliance

In the validation phase, 80% of patients agreed or somewhat agreed with sensory statements including “is easy to drink”, “has no bitter taste”, and “is not too sweet”. The researchers determined that the final product had to have 300 calories and 10g protein, be a clear oral beverage, and contain minimal micronutrients. Eventually, an acidified milk protein isolate was identified; trace elements were removed, and vitamins added to help counter a perception of metallic taste and add a cooling flavour.

The fact that the product was co-developed with patients and caregivers informed these unique sensory attributes and offered the emotional benefit of normalcy. This, in turn, can contribute to patient compliance and improved health outcomes.

Screening patients with chronic diseases from the general population is difficult. Research takes longer and may require compromises on criteria and design.

“Despite all of these challenges, developing products that delight these specialised patients and our consumers is both satisfying and rewarding,” Oreskovich said.