A preblend or premix is a mixture of components that have been blended together, in-house or by an ingredient supplier, and provided to a processor as a preliminary step in the production of a final food or beverage product. Another way of stating this, perhaps more mathematical in derivation, is that a preblend is a subset of the ingredient list of the final product, mixed together before addition to the rest of the set of ingredients. Why use a mathematical description? Because the rationale for using preblends is all in the numbers.
At first glance, it might seem inefficient or an unnecessary extra step to produce a preblend in house. Preparing one requires a commitment of time and resources that could make this step seem unnecessarily costly or time-consuming. But there are advantages to going in-house.
It is generally useful to equip a place separate from the production area for the necessary preblend operations. This typically involves storage space for small-volume and/or high-value ingredients; the equipment appropriate for weighing out smaller quantities of materials; blending equipment; any necessary packaging materials; and, of course, the staff and labor expenses required to accomplish the work. The environment and procedures are designed to offer more control over segregation of ingredients, and the weighing, mixing and storage of materials.
The components of the preblend are carefully weighed out and mixed together under strictly defined conditions. It takes time and resources to weigh each component of the system; perform the blending; make the necessary quality and food safety checks; and, if necessary, package the preblend, often in unitized quantities.
Given all the effort involved in creating a preblended ingredient system, it would seem to call into question the overall value of the investment. But the worth of preblended ingredient systems can be exemplified by a case study from one company that was working on a fluid, water-based formulation for a salad dressing that included xanthan gum. Xanthan gum needs to be vigorously dispersed to prevent the formation of lumps.
Xanthan’s purpose in such a category of formulation (e.g., dressings and condiments) is to thicken and give body as well as to emulsify. If the aqueous phase of the formulation is thickened slightly, it is better able to suspend particulates, such as herbs and spices. However, xanthan, if not perfectly balanced in the recipe, can develop a tendency to form lumps. These lumps are nicknamed “fish eyes” because, with their partially hydrated, wet and sticky outer layer shielding a dry inner layer from access to water, they do resemble just that.
Fish-eye lumps are difficult, if not impossible, to disperse. In fact, in most cases, when a formula develops this unsightly clumping, the recipe must be scrapped, and processors must start over with fresh material. The problem, however, is avoidable. Applying sufficient shear in the preliminary blending process, or pre-dispersing the xanthan in a highly soluble dry carrier (such as sugar or maltodextrin) allows the preparer to avoid the formation of fish-eye clumping.
A preblend of xanthan gum with an easily dissolved system component, such as sugar or salt, will allow simplified addition to water. In this case, the preblend ensures that the xanthan gum particles are already widely dispersed before they contact the water, thus allowing for more immediate hydration and reducing the risk of clumping.
Today, there also are available pre-hydrated or agglomerated versions of xanthan that disperse much more readily than the standard 80- and 200-mesh powders. Processors who do not have high-shear mixing equipment to assist in dispersion can opted for making or purchasing a preblend with maltodextrin. Maltodextrin will obtain good dispersion with available mixing equipment.
Blends in the House
David Manschot is an industry consultant with more than 20 years of experience working with custom ingredient systems for private label and contract manufacturers. He describes the role preblended ingredient systems can play in contract manufacturing. With more small- and medium-sized companies farming out processing to such intermediaries, and larger companies employing them for developing or fine-tuning prototypes or new products, the importance of reliable premixed systems is more apparent.
“In my experience, the concept of preblending is vital to contract and custom product processing,” explains Manschot. “These makers typically are challenged with short runs, widely dissimilar blends and high throughput requirements. In such environments, the types of equipment available and the attention to detail of the workforce play critical roles in achieving consistency, especially in complex blends.” Manschot acknowledges that this not unique to food production, but also applies to “any situation where greater control is required at individual steps in a process.”
Should a manufacturer wish to set up for in-house blending, Manschot suggests the blending equipment be positioned on load cells to allow assembly of the batch at the dump station.
“The capacity and precision of the load cells will often preclude the accurate measurement of minor blend components,” Manschot explains. “In these cases, the only means of achieving consistency is to pre-measure and preblend the minor components in a more controlled environment.”
There are other cautions for such in-house set-ups. “In high throughput operations, the line employees are frequently temporary or contract workers,” continues Manschot. “Variations in training, experience and attention to detail all can contribute to variations in batch-to-batch consistency. This can be addressed though training programs, but higher turnover rates still present an issue.”
“Another important consideration,” Manschot says, “is the tendency to overcompensate on minor ingredient additions in an attempt to ensure a uniform blend.” He adds that this becomes a significant problem when considering the use of high-cost or concentrated materials, like artificial sweeteners, vitamins or minerals. In these special cases, the use of a preblend is often an effective means of controlling costs as well as achieving greater batch to batch consistency.”
Plus, with a supplied premix, processors avoid having to contend with ingredients that can lose flavor (such as spices and herbs) or effectiveness (such as vitamins and minerals) when subjected to prolonged storage times or less-than-ideal conditions.
Time-savings, minimization of the risks of non-uniformity and simplification of operations provide the justification for the use of preblends in the final manufacturing operation.
For example, combining two similar components to be mixed in equal parts (a 1:1 blend) could be described as the simplest blending situation. If two types of cereals are produced in a ribbon blender, operators would load the first component, say 50kg of blue puffed rice. The same or a second team of operators then load the second component, say 50kg of red puffed rice. With the onset of blending, the red and blue particles will begin to commingle.
Initially, there will be larger collections of red particles within the mass of blue particles, and over time the mixing action distributes the particles more evenly—until a uniform blend is achieved.
In this simple scenario, the similar features of the particles—quantity, size, shape, density, texture and surface characteristics—facilitate the transition to a uniform mixture. Surface characteristics can include features such as cohesiveness/adhesiveness and hardness/softness.
However, if any of the features is changed (such as relative quantity, size, shape, density, texture, cohesiveness, etc.) of one of the components, the forces acting to blend the particles can be impeded. At a minimum, this will extend mixing time. Often, however, it can render achievement of a uniform blend almost impossible.
Taking the relative quantities in the puffed rice cereal example, if there is a large change to the ratio of red to blue puffed rice pieces—say from 1:1 to 1:99—achieving a uniform distribution of red particles within the mass of blue particles requires a protracted mixing time. As the mixing time required to attain uniformity increases, additional impacts are accrued, such that the integrity of the components can suffer.
This is especially true when one of the components is more delicate or friable than the others. By attempting to dilute a small mass of red particles in a much larger mass of blue particles, the forces acting to distribute the particles within the blender are acting on much fewer red particles and, therefore, more time is required to achieve uniformity, which means more friction on the individual pieces.
When the integrity of such a solid-to-solid mixture is subjected to damaging forces, the final mix could require sifting to remove unfavorable microparticulates.
There also are issues, such as “dead” spots in the blender, where mixing forces are dampened or blocked. This, also, can cause problems in achieving a uniform blend. The greater the ratio of components, the more pronounced the effect on the blending. All of these factors also lead to higher waste and increase ingredient and labor costs.
Blending two materials of substantially different particle size exponentially increases the challenges. Keeping with the cereal product example, consider white rice puffs flavored with a finely powdered, high-intensity sweetener, such as aspartame. The different sizes and weights of the particles in this case would probably make obtaining a homogenous blend nearly impossible. Rather, the puffs and the powder would tend to order themselves by size and weight.
With a blend of dry powder and a liquid component, depending on the quantities of each, it might be possible to add the liquid to the dry blend in a slow and uniform way…for example, using a fine spray over the bulk of the blend as mixing is occurring.
Under optimum conditions, the liquid is spread evenly over the dry particles in the blender, and a uniform mixture is obtained. As the amount of liquid to be added decreases, a point is reached where addition to the dry blend cannot be accomplished in a simple, uniform way. This will result in hot spots and lumps that will not blend out in a timely manner.
There also are situations in which the presence of free moisture can adversely affect other components of the blend. However, an aqueous solution of a critical component can be preblended onto a suitable dry substrate. This will serve as both a carrier and will isolate the water from contact with other ingredients.
Makers of premixes will sometimes effectively employ a pre-dilution of the minor blend component to fold into the major component. The benefit is better control over the dosage of the minor component; reduced mixing time of the final blend itself; and a reduction in the potential for non-uniformity.
These effects are perhaps most noticeable when using blends containing minute quantities of highly active components, such as texture modifiers, flavors, colors, high-intensity sweeteners, vitamins and minerals.
In the case of blending rice puffs and powdered aspartame, if the sweetener were first treated in a preblend operation where it was agglomerated with a suitable carrier, then the larger particle size of the agglomerate would favor better blending with the rice puffs. Or, the sweetener could be spray-coated onto a portion of the puffed rice. Segregation could be reduced or entirely eliminated in the final blend.
The More the Merrier
Opting for a supplier-provided premix is worth considering when assessing the impact of having to prepare a multi-component dry mix formulation from scratch, at each work station, each time a batch is prepared. All the components must be either unitized or pre-weighed, ideally in a separate area, then transported to the work station. Each component is added in a specified order, with mixing at timed intervals to ensure uniformity.
As the complexity of the formulation increases, so does the risk of missing an addition or of adding an incorrect amount. So, too, are the number of failure points inherent in any complicated chain of process. If the batch contains multiple small-volume components, then the risk of insufficient mixing resulting in non-uniformities also increases.
Another example of a useful preblend is a liquid or dry mixture of synthetic food colorants, particularly FD&C Blue #1. The dye powder is effective in very low doses and is notoriously fine and light. Moreover, it is susceptible to broadcast over a large area when mishandled. A liquid preblend eliminates all concern about the intensely blue dust and simplifies measurement of the correct dosage.
A dry preblend of such a colorant system is not as effective at eliminating all dust concerns. However, it still serves to dilute the active component sufficiently to ease handling and shorten blending time in dry mixes.
The incorporation of vitamins and minerals into fortified products is perhaps one of the most common examples of premixes in food and beverage processing.
“Many of our healthy snack products are fortified to meet consumer nutritional needs,” says Jeremy Zobrist, owner of Watershed Foods LLC, a manufacturer of healthy snack products. “We work closely with suppliers to design the right mix of vitamins and minerals to meet our requirements. Our operations team then receives a customized preblend that simplifies the batching process and helps insure lot-to-lot consistency in our fortified products.”
The quantities of pure vitamins and minerals necessary to achieve normal levels of fortification are extremely small. They also are expensive. Manufacturers of vitamin and mineral premixes are able to purchase the individual components in cost-saving amounts; however, few food and beverage makers can take advantage of these savings.
Preblending with an appropriate carrier allows for the pre-dilution of these active components before combination with the rest of the system, thus shortening blending time and reducing the risk of non-uniformity due to incomplete dispersion.
Many food ingredient manufacturers and distributors offer functional ingredient or nutraceutical preblends as a value-added service to their customer base. These preblends offer benefits, such as time savings and simplification of handling during manufacturing, as well as pre-certification of the concentrations of minor—but critical—components.
Functional preblends can be as simple as a blend of two miscible liquids or as complex as a multi-component blend of vitamins and minerals used for fortification. They can be even more complex, as when both types are combined in a single product, such as an energy beverage.
Keep it Close
Sometimes, the rationale for a manufactured premix is as simple as protection of a custom formulation.
“As a manufacturer of a range of healthy food products that meet the demanding quality and nutrition requirements of our customers, we co-manufacture certain products for our partners,” says David Howell, R&D manager for Betty Lou’s Inc. “The operations environment is a demanding one, requiring attention to quality, consistency and food safety. We also must ensure that our operations run as smoothly, efficiently and cost-effectively as possible. Given the complexity of many of our formulations, and the stringent quality requirements, we often find that the use of preblends allows us much greater control of consistency, as well as improved efficiency of through-put.”
Howell notes that the care taken in preparation of preblends ensures consistency in the end-product from batch to batch and run to run. “We also save time in the batching steps, where we avoid the sometimes lengthy process of measuring, dispensing, and blending ingredients for a complex formulation on the production line,” he says.
Howell continues, “At times we find it convenient to ‘spec’ preblends from certain key suppliers. These suppliers usually offer a particular benefit, such as access to certain key ingredients, or possession of key processing technologies, that we use to our benefit. We work closely with them to develop the guidelines for quality and uniformity that are required to ensure consistency in our finished goods.”
Preblends can be prepared and supplied ahead of time; transported, stored and allocated under controlled circumstances; and, if convenient, distributed in multiple-batch quantities. By utilizing well-chosen preblends, the operation at the work station is simplified, and blending times for complex mixtures can be reduced. Waste is avoided, and expenses are kept predictable and controlled. Best of all, any unforeseen expenses that can be inherent in building a premix of multiple components are not assumed by the maker of the end-product.