Wheat during the germination phase of the sprouting process. Photo courtesy of Rahr Malting.
Sneak Peek 2 – Sprouted Grains as a Food Ingredient
This is the second blog in a series dedicated to providing a preview to a book chapter written by Vanessa Brovelli, Darrel Nelson and Sean Finnie from Bay State Milling’s Research and Development Team. The chapter appears in the book Sprouted Grains: Nutritional Value, Production and Applications. Editors; Hao Feng, Boris Nemzer and Jon Devries. Published by AACC International. This blog will cover the processing of sprouted grains and we’ll finish the blog series by discussion the functionality and applications of sprouted grains.
What happens in the processing facility?
Sprouted ingredients can be sold in two different forms; either a wet-mash or a dry ingredient as flour or grain. Regardless of whether the material is a wet-mash or dried, the first two steps are the same- steeping and germination. In steeping, the grains are soaked in water until they reach the desired moisture content. Once the proper moisture content is achieved, any excess water is drained and the material is allowed to germinate. Germination can occur in a number of different types of vessels. A typical vessel is a germination bed, similar to what is used in the malting industry. Regardless of germination vessel, the germinated grains need to be kept in an aerobic environment with constant and consistent airflow and temperature to ensure uniform germination rate throughout the material. Once germination is complete, the wet-mash material is processed immediately into the final end-ingredient, or it is frozen for use at a later date. If the sprouted grain is to be processed into flour, the material is moved into a dryer or kiln to remove water to a final moisture content of 10%-14%. Drying or kilning can proceed at various times and temperatures, which are unique to each manufacturer. These setpoints are optimized and proprietary for product differentiation, and to achieve product consistency.
The Tools and Equipment used to Evaluate Sprouted Grains
Sprouted sample preparation for analysis is a critical step for accurate data collection, thus grinding equipment selection is important. Sprouted grains are sometimes ground and analyzed during the sprouting process as a quality measure to understand the rate of germination, and determine an appropriate end point. As an additional quality measure after drying, many manufacturers will grind a sample from the sprouted dried lot for quality parameter testing. Most sprouted products will grind or mill differently than the unsprouted raw grain, therefore, there may be a need to have different grinding or milling equipment and procedures to prepare the sprouted grain for analysis.
Particle size will impact moisture, functionality, and other characteristics that are key concerns and should be evaluated prior to choosing a grinding or milling apparatus. There are many manufacturers of sample preparation grinders with a variety of models offered, ranging from hand cranked grinders to laboratory grade mills with no two mills or grinds alike. Some mills will refine and fractionate the various components while most simply grind in a single stream. Therefore, it is vital to understand the sprouted ingredient test requirements for proper selection.
Falling number analysis is an indirect method of measuring enzyme activity, particularly α-amylase. Originally developed by Perten Instruments to detect field sprout damaged wheat, it is now being used to measure germination or sprouting levels in wheat. According to the AACCI Method 56-81.03, “This method is based on the ability of alpha-amylase to liquefy a starch gel. The activity of the enzyme is measured by falling number (FN), defined as time in seconds required to stir and allow stirrer to fall a measured distance through a hot aqueous flour or meal gel undergoing liquefaction. Alpha-Amylase activity is associated with kernel sprouting, and both of these are inversely correlated with FN.” In other words, the more germination that has taken place, the greater the alpha amylase activity, resulting in a less viscous starch gel and therefore a lower falling number.
Traditionally, falling number analysis is used on sound wheat and rye, but, as the method attests, has applications in sprouted grains, especially because the starch-degrading enzyme alpha-amylase is known to increase as part of the sprouting process. A typical falling number specification for sound wheat is above 350 seconds, although this is variable based on the grower or miller. The falling number of sprouted wheat varies widely among suppliers, but values of 300 seconds and lower are common.
Rapid Visco Analyzer
The Perten Rapid Visco Analyzer (RVA) is another apparatus that indirectly measures enzyme activity. According to AACCI Method 22-08.01, “This method is based on the ability of alpha-amylase to liquefy a starch gel. The enzyme activity is measured as the stirring number (SN), defined as the apparent viscosity in rapid visco units at the 180th sec of stirring a hot aqueous flour suspension undergoing liquefaction. By the action of the hydrolytic enzyme alpha-amylase, viscosity decreases and SN increases. Enzyme activity is also an indication of sprouting of grains. This method is applicable to both meal and flour of all small grains.”
The original RVA systems typically gave only three data points as results; the peak, hold time, and final viscosity. The newer systems employ software that records the viscosity over the duration of the assay. This yields more information about the sprouted grain to produce results with more discrimination. RVA analysis can used to compare multiple sprouted flours to one another, and is a good indicator of cook-up or bake performance when compared to unsprouted flours. It can provide a formulator with indications of pasting and gelatinization temperature, comparative viscosity increase rates, comparative hot viscosities, and starch retrogradation information, all of which are important parameters in new product development.
Functionality and applications of sprouted grains
… To be continued in the next blog posting.