AIB International, located in America's heartland is home to eight unique labs that are the heartbeat of the company since the facility was built in 1978.
In the Science Training Lab students begin to explore analytical tests that are used to determine characteristics of flour and other bakery ingredients. Like AIB’s Pilot Plant Labs, it was created to provide a safe place for baking students to learn first-hand how to run a variety of tests, and, more importantly, how to interpret the results.
The lab is composed of two rooms: classroom and rheology lab. Last week we featured the classroom side and this week we are featuring the rheology side.
The rheology lab holds all of the equipment used to measure how substances behave under stress. The floor-space was expanded to nearly double the size last year during AIB’s building remodel, allowing less crowding between instruments.
“We receive good support from instrument suppliers”, said Debi Rogers, Director of Baking Services. “A few companies have donated equipment, some loan us equipment, and others provide heavy discounts on purchases.”
Rogers is often asked whether falling number measures damaged starch – and the answer is “no”. Damaged starch is physically damaged starch granules, and is generally the result of milling hard wheat into flour. It is a little more difficult to measure than alpha-amylase activity. Amylase activity and damaged starch content are related, in that damaged starch is one of the substrates, or “foods”, for amylase enzymes.
Damaged starch also has a major impact on flour absorption. Most bread flours contain low levels of these beneficial damaged starch granules. The common tests to measure damaged starch use enzymes to break down starch without heating or gelatinizing the sample, and measure the sugars produced. There is also an instrument that measures iodine absorption, again of the unheated starch.
Falling number, amylograph, and Rapid Visco Analyser all measure viscosity of a starch-based slurry as it is being heated under controlled conditions. The sample, usually flour, is mixed with water and immediately placed into the instrument and heated.
PRO TIP: place water into the falling number tube before the addition of the sample to prevent the flour from sticking to the bottom of the tube, and don’t over shake.
When used in this manner, the purpose is to examine alpha-amylase activity. Alpha-amylase is an enzyme that breaks down damaged or gelatinizing starch into chunks, called dextrins. Thus, the thinner the cooked paste at the end of the test, the more alpha-amylase activity. Another flour enzyme, beta-amylase, breaks the dextrins into sugars that can be used for yeast fermentation and that contribute to browning.