Wednesday, 1 May 2013

Texture Evaluation of Breakfast Pastry

A client asked FTC to perform a food testing study on their breakfast pastry to evaluate the differences in texture caused by variation in the cooking methods. The producer was using sensory in determining how different cook times can affect the texture of their product. Their goal was to rely less on the subjectivity of sensory and apply a test method that is more objective. Food Technology Corporation developed a method that allow them to do this in a consistent and repeatable way.

Materials and Methods

All testing was done using FTC’s TMS Texture Analyzer, fitted with a 250N Intelligent Load Cell (ILC). The fixture used for this particular application was the TMS Light-Weight Three Point Bend fixture. This fixture works by supporting the sample between two fulcrums and then using another fulcrum to bend the sample. Even though this test is designed to evaluate the crust of the product, the inner filling is going to affect the results somewhat. This has to be taken into consideration.
Each test replication involved the upper fulcrum moving down to a displacement of 40mm at a speed of 250mm/min. This displacement was selected as it was far enough to cause the samples to break. Samples were prepared in the 3 groups.
In food texture testing it is very important to be specific and define what, for example, “under toasted” means, as it can be interpreted differently amongst us. We defined the different levels of toasting as such:
  • Toasted to Directions = golden brown on outside and filling inside is completely cooked and hot
  • Under Toasted = semi-golden brown on the outside, however the filling is not fully cooked and still partially cold
  • Over Toasted = burnt and crispy on the outside, filling is hot and completely cooked on inside
This method was applied in order to show how a change in the cooking process affects the overall texture of the crust of the product. After toasting, the samples were allowed to equilibrate to ambient temperature so that any variation would not affect the results.

Results and Discussion

Graph below shows the results. The X-axis is displacement and the Y-axis is force. 2 samples were tested "under toasted", 2 samples were tested "toasted to directions" and 2 samples were tested "over toasted".


Conclusions

The graph shows the Over Toasted sample being the firmest - with the higher peak forces. Under Toasted samples in the middle and Toasted to Directions samples the ones with the lowest peak forces.
Under Toasted samples are showing firmer than the Toasted to Directions most likely because the filling is not being cooked all the way, remaining more solid-like and cold, therefore, harder when the upper fulcrum of the 3-point bend tries to break through it.
The Toasted to Directions samples were reading lower forces because the inside filling was cooked all the way and runny, therefore, it doesn’t take much force for the upper fulcrum to break through the pastry.
Lastly, the Over Toasted samples registered the highest force readings and require the most force to break because the outside was crispy and hard due to over toasting the pastry.
While these results may not be conclusive, further testing would likely produce similar results for the three different cook methods, bringing the producer to the understanding that time and temperature used to toast the breakfast pastry will certainly influence the expected texture.
Find out more about bakery industry texture analysis solutions here.

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