Texture Profile Analysis

Objective

To conduct texture profile analysis

Background

Food texture is an important parameter measured in food laboratories due to its relationship with the human sensory experience. Words that are used to describe texture may include hard, brittle, chewy, gummy and springy. These characteristics can be measured by having a sensory panel taste the food and providing their subjective feedback. But for more objective measurements, texture analyzers are used. The one that we will use in this lab is the CT3 Texture Analyzer from Brookfield Engineering. This instrument runs two type of tests i.e. a compression test and a texture profile analysis (TPA) test. A compression test is a simple one-bite test that tells you how hard the product is when you bite into it for the first time. The TPA test is a double-bite test providing more complex data including gumminess, springiness, chewiness, and adhesiveness.    

During the TPA test, a probe descends and makes contact with the sample. Once a minimum trigger force is achieved the probe descends for a set distance at a specified speed. The probe then ascends all the way back to its original position and then wait for a specified time before making its second decent for another reading. It’s important that the wait time between the first and the second compression test is not too long or too short. If too long, it may allow the food material to fully recover, making the first and the second reading appear the same. Alternately if the wait is too short, it will not allow time for the material to recover sufficiently. The graph below shows you a typical profile of a TPA test and data that is derived from it. 

Figure. Texture profile analysis (TPA) graph. Source: texturetechnologies.com

Data Interpretation

Data derived from the graph include:

1. Hardness: The maximum force achieved at the first bite. Customers may experience this as the degree of crunchiness, crumbliness, or brittleness 
2. Adhesiveness: The amount of work needed to overcome attractive forces of the food to another contact surface. Customers may experience this as stickiness, tackiness or gooeyness
3. Cohesiveness: How well the food withstands the second deformation relative to its resistance under the first deformation. In other words, it’s the extent to which the food deforms when compressed. Cohesiveness  is calculated as area 2/area 1
4. Gumminess: The energy required to disintegrate a semi-solid food until it can be swallowed. It is calculated as cohesiveness * hardness
5. Springiness: The degree to which the food returns to its original height after being compressed. It is calculated as distance 2/distance 1
6. Resilience: How much a product fights to regain its original shape and size. It is calculated as area 4/area 3
7. Chewiness: The energy required to chew solid food until it can be swallowed. It is calculated as gumminess * springiness 
8. Fracturability: The force at the first peek. Hard cookies will have multiple fractures indicating a crispy texture 

Materials and Equipment

1. Food Samples – Chicken sausage, diced cheddar cheese, white bread, diced tofu  
2. CT3 Texture Analyzer
3. Laptop for remote use of the texture analyzer

Method

1. Divide samples into two sets (1) a set to be evaluated by taste and (2) a set to be evaluated by instrumentation
2. Taste samples and describe the texture using narrative or descriptive words  
3. Put the CT3 Texture analyzer in TPA mode and preset the following parameters: target, trigger load, hold time, test speed and return speed
4. Select an appropriate probe for measuring your sample. A flat probe is suggested instead of a sharp-edged probe since you will be doing a TPA test. This will allow recovery of the food sample after the first bite.
5. Make sure that samples are of the same size. For example, breads are sliced at the same thickness and cheese, sausage and tofu are diced and cut at the same dimensions
6. Place sample on texture analyzer stage and measure. Remember that this is a two-bite test so wait to allow the probe to complete two cycles
7. Repeat the measurements two more times to get triplicate readings
8. Record the values that appear on the screen of the machine or computer if using remotely. Report mean: hardness, adhesiveness, resilience, cohesiveness, springiness, gumminess and chewiness
9. Print graphs showing the texture profile of each sample (Note: Only possible when the instrument is connected to a computer for remote measurement)    

Lab Questions

1. Calculate the standard deviation between the three replications of sample measurements. Why are there variations? How could you reduce this variability? (10 points)
2. Describe how food composition and processing factors could impact textual quality of food (10 points)
3. Describe the texture of each sample based on your sensory evaluation. (5 points)
4. Why is your own taste not a reliable method to determine texture? (2 points)

Reference: Overview of texture profile analysis. Retrieved texture technologies.com.