Tribology And Dairy Products

Wednesday, September 13th, 2017

Health-conscious consumers want low-calorie alternatives for food and beverages and food manufacturers are rushing to meet that demand. Using tribology as an analysing tool, innovations leading to acceptable mouthfeel and texture in products have become more effective, accurate and less time-consuming.

As consumers become more health-aware, the demand for foods with healthy claims such as ‘low-calorie’, ‘low-fat’ and ‘lowsugar’ is on the rise. Dairy-based food and beverages contain both fats and sugars, and it is one of the common places where consumers look at to cut their calorie and sugar intake.

To respond to this growing demand, much research and development have been done and grocery shelves are now being filled with healthy alternatives. However, the uptake of healthy products is slow whilst obesity rate continues to increase globally. This is due to consumers stating that the overall sensory experience for the healthy alternatives do not meet their expectations.

This creates a room for improvement on the sugar-free dairy products, but current studies still lack behind in creating an acceptable taste and mouthfeel for sugar-reduced dairy products.

Challenges In Measuring Mouthfeel And Texture

Mouthfeel refers to the tactile aspects of texture perception and rheology is commonly used to measure mouthfeel due to its relationship to physical stability and initial texture perception.

The food oral process is a complex process where food undergoes dramatic multi-scale deformations in the mouth. When food enters the mouth, its physiological aspects deform; the teeth chews and grinds, the tongue stirs and pushes. Chewing forms a cohesive and lubricated bolus mixed with secreted saliva and liquid food ingredients after being broken into particle sizes of micron to sub-millimetre level. After which the food is swallowed, moves down from the oesophagus and into the stomach.

Except for the point at which food enters the mouth (for example, first bite of solids, initial thickness of liquids), there is no way to predict texture and mouthfeel precepts using fundamental rheological properties of the food and beverage or with a texture analyser. Therefore, scientists at the Cargill Global Food Research Group set about finding a new way to model mouthfeel that went beyond rheology and to more accurately imitate what goes on inside the mouth when a beverage is consumed.

Currently, the most commonly used method for sensory evaluation is by having sensory assessors to describe or score foods, after which the information is fed into a statistical software for data analysis, and the final food sensory evaluation will be produced. But often sensory panels have mixed results, as taste is a very subjective assessment.

The word tribology describes the study of friction and lubrication between interacting surfaces in relative motion. Although tribology is a branch of mechanical engineering, recent years have seen it being used for understanding texture and mouthfeel as the number of interacting surfaces in the mouth during food consumption.

The Use Of Tribology In Sugared Products

To cater to the demand of acceptable healthy alternatives to sugary products, Cargill has developed a number of suitable low-sugar, low-fat milk content system solutions—Trilisse series and Protex Best series products, based on tribology technology.

Figure 1 is the tribology test results of a sugar-free beverage Trilisse QMF50. The lubrication curve is very different for the sugar-free drinks and diet soda drinks, indicating the taste difference between the two products is high. However, when Trilisse QMF50 is added to the sugar-free drink, the curves gradually come together. When the concentration of Trilisse QMF50 reached 800 ppm, the lubrication system and the diet soda drinks are basically equal. Currently, the Trilisse series can be used to improve the taste of products with a 10 percent sugar content reduction.

Tribology’s Role In Mouthfeel And Texture Analysis In Dairy Products

As the growing demand for dairy products has caused the supply of milk to become increasingly stretched, companies have begun developing substitutes for milk. However, reducing the milk content in a product causes a decline in the stability and also a change in taste and texture such as creaminess and smooth mouthfeel.

Theoretically, the higher the milk content in dairy drinks, the more lubricant property they have and the creamier, smoother and more slippery they will be in terms of mouthfeel. With the use of rheology and tribology technologies, Cargill has developed a total solution for 50 percent milk replacement content system. With this, the stability of the product has shown improvement and the product taste (creaminess, smooth feel, etc.) has also a corresponding improvement.

Figure 2 shows that the friction of 50 percent milk can be similar to values between that of 80 percent and 100 percent milk. The ingredient is also able to improve mouthfeel by modifying the lubricant property. The tribology result is also consistent with that of inner sensory results.

Pectin is an ingredient and a natural component of plants. As a food ingredient, it can be used as a gelling agent, thickening agent and stabiliser. Pectin is used in diverse applications, such as yoghurt, confectionery and acid milk drinks, to optimise the mouthfeel of fruit-based beverages and as a protein stabiliser in acidified dairy products.

In particular, pectin plays an important function in yoghurt beverage products. It is a stable protein under acidic conditions, thus preventing the yoghurt from producing precipitation and giving it a more creamy flavour and texture. As the effects vary according to the source and extraction techniques of the pectin, it is therefore necessary to establish a rapid and effective pectin evaluation method to help manufacturers quickly filter suitable pectin to develop new products.

Cargill uses tribology technology in taste evaluation to objectively determine the taste differences between the pectins. For example, Figure 3 shows the different effects of two pectins in an acidic dairy drink. Pectin A, which has a fat content of 0.5 percent, has the closest lubricating properties to the control sample as compared to pectin R. This gives the dairy drink infused with pectin A a much closer taste and mouthfeel to the control, while pectin R has a different taste from the control which means that there is a higher chance for the product to be rejected by consumers die to taste.

In summary, rheological studies are no longer sufficient when evaluating mouthfeel and texture. Lubricating properties of food ingredients and taste change can be monitored with tribology technology, and with Cargill’s patented technology and knowledge in terms of improving taste, we can together with our customers, more effectively identify differences in taste and develop an optimised texture solution that will suit their needs.