The new look of bakery lab instruments
Nov. 1, 2014
by Laurie Gorton
Don’t be surprised if your lab staff submits its next budget request with a substantial bump up in spending on instruments and supplies. The demands they face in monitoring specs have gotten much more complicated in advance of the implementation of the Food Safety Modernization Act. Traceability ups the ante here.
External market trends and internal cost controls also put pressure on keeping ingredient performance in line with expectations. This is particularly true for companies serving the gluten-free market. Not only must those ingredients produce the results expected, but also their relatively high cost means even tighter control over waste.
Recently, Baking & Snack reporters have found a number of bakeries installing flour testing instruments similar to those used by millers to make sure flour fits finicky automated processing lines. Additionally, routine testing in the bakery is connecting at-line and on-line stations with the lab and corporate QC via internal data highways.
The performance linkage
Improved data reporting aids the formulator and quality assurance manager when they need to relate the findings of one test to another. For example, automation of solvent retention capacity (SRC) data collection provides results on the network-forming components in flour and, thus, illuminates the results of alveography, which is an overall measure of dough strength.
Touch-screen equipment control panels, now common inside bakeries, have made their way into the world of lab instruments, too. Recently, they have been coupled with advanced software packages that operate the instrument and analyze its readings.
For example, Brookfield Engineering, Middleboro, MA, provides this interface for its family of RST Touch Screen Rheometers. The company recently introduced its Rheo3000 V.2 software to simplify operation of these systems while deepening their analytic capacity.
All the operator has to do is enter the shear stress or shear rate, temperature and test time. The instrument does the rest, performing the tests, collecting the data and analyzing the results. Tests cover a wide range, including viscoelastic modulus, yield stress, viscosity vs. shear rate profile, thixotropy calculation, creep behavior, recovery after flow and temperature sensitivity.
The functionality question
Measuring flour by its SRC reveals the quality of its three network-forming polymers: damaged starch,
glutenins and pentosans. These components exert themost influence on dough behavior during processing and baking.
SRC is a highly revealing test based on the enhanced swelling behavior of individual flour proteins in selected diagnostic solvents, but this approach had its limits. “Unfortunately, the manual method has certain drawbacks related to the repeatability of the test due to handling variation,” said Ian Trood, vice-president, business development, Chopin Technologies, Inc., Olathe, KS. “By automating the popular SRC test, we are able to eliminate the problems of repeatability often associated with the manual method. It also makes the test much more applicable for routine R&D environments.”
The company introduced the SRC-Chopin instrument this year. In the milling lab, it can be used to measure wheat tempering, flour blending and chlorination. Used in baking labs on soft wheat flours, readings will predict cookie, bread and cake dough performance, and hard wheat flours can be characterized by their potential loaf volume and crumb structure.
One big benefit is its efficiency. Mr. Trood explained that technicians will no longer need to be assigned solely to running SRC tests. “Using the SRC-Chopin, they will set up the process, activate the equipment and then continue doing other routine tasks in the laboratory,” he said.
Perten developed its doughLAB to be a multifunctional instrument. “Bake labs can create specific tests to study flour performance using variable temperature and high speed/energy mixing,” explained Wes Shadow, business development manager, Perten Instruments, Inc., Springfield, IL. High-torque tests, for example, reveal the characteristics of crumbly doughs for pastry, cookie, cracker, pasta, noodle and other low-water-absorption doughs. Defined energy input tests stop the instrument’s mixing action when a specific amount of mechanical energy has been applied, thus allowing testing for baking performance and finished product texture.
“With the Perten doughLAB, millers can quickly calculate flour blends to meet target water absorption specifications using the software,” Mr. Shadow said. “This lets them do complex ‘what if’ analyses without having to run lots of tests.” Blend models can help manage crop changeover issues and design flour blends to maintain customer specs.
The gluten conundrum
Gluten represents an enormous fork in the road for bakers and their formulators. Take the gluten-free turn, and you must maintain constant vigilance to keep this protein out of your ingredient supply. Take the other turn, and you’ll want to monitor gluten content in order to optimize finished baked foods.
Producers of gluten-free foods have a basic need to test incoming ingredients for the forbidden protein. However, bakers, millers and wheat breeders have a quite different need: Is the gluten quality of the flour, whole grain, bakery mix or added vital wheat gluten suitable for the application?
When the goal is gluten-free formulation, the rheological properties of hydrocolloids and gluten-free cereal flours must be quantified so that dough structure can be optimized. These highly hydrated doughs contain a lot of water, which changes rheology aspects drastically and also must be monitored closely.
Chopin recommends two instruments to help do the gluten-free job. The Mixolab measures the consistency of doughs during mixing and under changing temperature. These results describe starch gelatinization and retrogradation —
factors in shelf life. Mixing under constant temperature gives information on changes in water level, consistency, stability and other rheological factors.
The second instrument Chopin recommends is the Rheo F4. It measures the pressure within a sealed temperature-controlled tank containing a dough sample. Its results describe total gas production (a.k.a. yeast activity) and retention of that gas and, thus, measure characteristics of dough during proofing. Gas retention is lacking in gluten-free doughs and causes complex problems with volume and baking performance. Protocols can be customized to handle yeast-raised gluten-free products. By knowing the dough’s tolerance, the baker can set up the oven to properly bake them. Its information also helps optimize proofing conditions and mixer settings.
The other road
Wheat’s protein enables creation of the light, airy texture that makes many baked foods so popular. “But protein content does not guarantee flour performance,” Mr. Shadow observed. “Different types of end products require flour with different characteristics.”
The Perten Glutomatic measures gluten quality in flour, wheat, durum and semolina. It provides a simple test, suitable for use at grain or flour receiving stations. “Results of this test help wheat millers test flour streams for gluten formation quality and quantity,” Mr. Shadow said. “The results are used to calculate flour blends and vital wheat gluten addition.”
For those who want to dig deeper into the protein performance of their flours, the Brabender GlutoPeak instrument reports the performance curve of the tested material, unfolding the complexity of aggregation and breakdown of the gluten network. A small quantity of flour, 7 to 9 g, is mixed with water, and the test is run for one to 10 minutes, depending on the sample. Strong flours, such as those suitable for bread or pasta, show high torque and short gluten aggregation time, also termed peak maximum time (PMT). Weak flours, as are used for cookies and crackers, reveal low torque and long PMT, and very weak flours for making wafers or batters exhibit much delayed PMT or no aggregation at all.
The company’s GlutoPeak provides a quick test method to check delivered grain or flour in relation to its quality specs. “The results will help the miller control and optimize the receipt of grain,” said Marc Gelautz, marketing, Brabender GmbH & Co. KG, Duisburg, Germany. “He can decide quickly which quality the grain has. Later in the process, the instrument can help find the best mixtures of flour for requested quality.”
The instrument is easy to handle in daily use, taking only minutes to perform its analysis. “Every new flour [received by the bakery] can be checked very quickly,” Mr. Gelautz said. “For R&D, it would be also very helpful because of the short test times when new types of flour are checked.” The GlutoPeak correlates well to bake tests, thus minimizing the number of such procedures needed.
Digging deeper into protein performance, the Bastak 6100 gluten washer gives results that determine the best use for a given lot of wheat or flour. “After analysis by this instrument, the user can determine the best use — baking, feed or other products,” said Suzan Kizilok, foreign trader and food engineer, Bastak Food Machine Medical Marketing Co., Ankara, Turkey.
Previously, testing for the amount of wet gluten in whole wheat and refined flours was done by hand-washing a solution of flour and water and extracting the wet gluten, a tedious and time-consuming activity. “[That method] had lots of disadvantages, and the results were not trustable,” she said. Water temperatures, washing time and action — all could vary with the person doing the test.
The automatic gluten washer controls the amount of water, its temperature and the energy put into the washing/kneading action, making test conditions the same every time. Or the instrument’s settings can be changed to test different times and conditions, as desired. Data collection allows recording of the sample’s source as well as test results.
The gluten washer can be used as a system with the company’s Dry Gluten 2500 and Gluten Index 2100 devices. The 2500 system gives results as 100% gluten amount in wheat without water, and the 2100 unit quantifies gluten strength and quality.
The sensory connection
Color and appearance monitoring has been active on snack lines sorting potato and tortilla chips for a good number of years. Coupled with reject systems, they keep substandard pieces out of fast-moving product streams. Such technologies have proven their worth on bun lines, too. But automation of other senses — smell and taste, in particular — is only now emerging in practical form with lab-scaled instruments: the so-called e-nose and e-tongue.
Gas chromatography provides the basis for the Heracles electronic nose instrument from Alpha MOS America, Hanover, MD. As an option, the system’s software uses a database library of more than 40,000 compounds for aroma and chemical analysis. The software characterizes compounds separated by the gas chromatograph matches them based on Kovats Index.
The company’s Astree electronic tongue analyzes a liquid sample, detecting all compounds responsible for taste and calculates the resulting data to asses basic tastes (sweet, bitter, sour, salty, umami) and other gustatory components (metallic, pungent, astringent and so forth). The instrument uses chemically sensitive field-effect transistors to make potentiometric measurements and sensors tuned to ionic, neutral and chemical compounds responsible for taste. An optional taste-ranking module helps classify similar products based on their intensity of attributes such as sweetness, bitterness, sourness, saltiness, umami and so on.
Handheld color measurement systems found a permanent home in bakeries nearly a decade ago, and they continue to be refined. The BC-10 from Konica Minolta Sensing Americas, Ramsey, NJ, quantifies color of crusts and most bakery and snack food products, as well as block yeast, brown sugar, calcium propionate and blended flour. All the user does is place the meter on a sample and press a button.
The newest wrinkle in color monitoring at the lab level is the C-Cell Colour System from Calibre Control International Ltd., Warrington, UK. Introduced at the 2013 International Baking Industry Exposition, this instrument uses proprietary Crust Unwrap technology to profile the external crust of baked foods and quantifies the color on the surface and crumb. It can analyze, identify and quantify inclusions such as dried fruits, seeds and chocolate chips. The basic C-Cell imaging system analyzes cross sections (slices) of baked foods for air cell and hole characteristics including number, diameter, area, volume, distribution and clustering.
The changes being made in bakery and mill lab instrumentation reflect the need to know more about raw ingredients, in-process materials and finished goods. The results reflect how science of baking supports the art of making safe, appealing baked foods for consumers.