Bread Bakery

Bakery Bread Image TA

APPLICATION
Establish a standard compression test method for evaluating the firmness of bakery products.


TEST OBJECTIVE
Firmness is accepted as a measure of freshness and quality.  This method is useful for measuring freshness and quality in product development and quality control.


TEST PRINCIPLE
Quantitatively measure the force required to compress the bread sample.


BACKGROUND
The American Association of Cereal Chemists (AACC) developed a standard method for the assessment of bread samples by deformation. The force to compress a bread sample a specific distance simulates gentle squeezing by the consumer when selecting their loaf at the supermarket.


METHOD
One slice of bread 25 mm thick or two slices (each 12.5 mm thick) can be used.  The slices can be cut mechanically or by hand provided the end three slices are discarded and the crusts are not removed.  A 38.1 mm Ø probe (TA4/1000) at a test speed of 2 mm/s.  The location of testing is the center of the bread slice(s) avoiding non-representative areas of crumb.  Sample is subjected to 40% deformation and compression load at 25% deformation is recorded in either Newton’s or g.  Test a load of three samples per loaf. 

Settings:
Mode: Normal
Speed: 2 mm/s
Distance: 10 mm
Trigger : 5g



RESULTS
The following is a result graph (using TexturePro CT Software)

Baked Bread Graph TA1
Figure I

EMPIRICAL FACTORS
Test conditions that will affect results generated:
1. Sample size
2. Sample age 
3. Test probe employed
4. Position and consistency of sample location

Sample conditions that will affect results generated:
1. Formulation and composition
2. Baking or processing treatments 
3. Storage conditions imposed on loaf

Sample Description
Product Name
Aging Firmness at 25%
Bread Test One Day 1.956 N
Bread Test Two Days 3.805 N
Bread Test Three Days 4.884 N


RELATED TESTS
TPA type assessment of bread sample
Measurement of bread strength and extensibility
Stress relaxation as an indicator of bread staling


DISCUSSION
The structure of bread can be defined as a solid foam colloid with multiple pockets of carbon dioxide distributed uniformly through its bulk.  Gluten forms the interconnected network that supports the carbon dioxide in small pockets.   The end result, when baked, is the aerated honeycomb texture characteristic of bread.

Texture analysis provides a valuable tool for insight into the quality of bread.  The method applied within this study has clearly quantified the effect of “staling” on the strength of the gluten matrix.

CONCLUSION
The texture measurement described has been shown to quantify physical characteristics of a range of loaves in the early stages of their life.  The simple compression test is ideally suited for production or development environments where it can give an indication of product staling or formulation in relation to enhancers, flour quality or the use of additives such as alpha amalayse. 

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