The four most important considerations when adding soy ingredients to products are taste, colour, functionality and cost. Jimbin Mai, PhD, explains how to work with soy to produce functional products—be they dry-blended, low-acid or high-acid beverages
As obesity rates and associated diseases such as diabetes and heart disease rise, researchers are exploring the role diet may play in the development or prevention of serious diseases. Because of the lower incidences of such diseases in certain Asian countries when compared with Western countries, researchers are examining the differences in diet between these regions. One major dietary difference is the larger consumption of soy by many Asian populations as a major protein source.
Today, East is meeting West as the health benefits of soy protein are becoming better known. In fact, according to information from Soyatech, sales in the soyfoods category in the United States grew by 13.8 per cent in 2002 to total nearly $3.6 billion. The Soyatech projection for 2004 is more than $4 billion.
Leveraging a growing trend, food manufacturers are looking to satisfy consumer needs by producing great-tasting, convenient and better-for-you foods by incorporating soy ingredients into already-established or new brands. Large food companies? investments in soy products are a key driver behind the growth in the mainstream category.
So, why incorporate soy protein into the manufacturing of consumer products? Simply put, its health benefits plus its high-quality protein (equal to meat, milk and egg protein) have made soy protein a top food ingredient choice. In addition to being a nutritional source for improving heart health, bone health and kidney health, as well as helping to prevent certain types of cancer, soy protein helps with satiety, is a highly digestible protein and helps maintain a nitrogen balance within the body.
Advances in the formulation of soy ingredients have also contributed to increased sales of soyfoods. Long associated with a distasteful ?beany? flavour, today?s soy products are better tasting than ever thought possible.
But what should food companies consider to be of prime importance in adding soy ingredients to products? First and foremost, taste, colour, functionality and cost. In addition, there are some general rules that will make companies? forays into producing soy-containing products more successful. First, not all soy is created equal in protein content. Depending on the finished product to be produced, manufacturers have many different types of soy ingredients from which to choose. Soy flour contains only about 50 per cent protein, whereas soy concentrates contain 70 per cent. Isolated soy protein retains 90 per cent of its protein during processing and contains fewer carbohydrates. Beyond soy flour, soy concentrate and isolated soy protein, a new soy protein ingredient is now available, made possible by a recently developed protein manufacturing process that enables further separation of the protein molecule from the carbohydrate molecule, resulting in a soy protein ingredient that has better functionality. This new soy protein process can be used in spray-dry, powder and liquid applications.
Flavour is first
As it relates to overall food and beverage formulation, taste is the most important factor—flavour, texture and mouthfeel. Because flavour is so imperative for product acceptance, manufacturers of soy protein often partner with a flavour house to ensure the best possible result. And the foremost soy ingredient manufacturers know they should employ not just a flavour house, but a flavour house that has years of experience with soy.
When flavouring soy protein, keep a few things in mind. First, choose a flavour that is innately compatible with soy protein. Any of the ?brown? ingredients work well, such as chocolate, caramel, malt, butterscotch, nut, honey peach, coconut and banana. If cream or butter can be used, both are always desirable. I would caution against vanilla, if at all possible. Vanilla is the most challenging flavour to make compatible with soy protein because it is often used as a ?milk? flavour in products such as soymilk, and there is a taste discrepancy when a consumer compares soymilk with regular milk. As companies make advancements in flavour ?maskers,? more exotic flavours are becoming popular. V8 Splash Smoothies—available in such flavours as peach mango and citrus blend—represent a good example of this growing trend.
Sodium chloride can be used to help with some of the soy protein aftertaste. And with low-carbohydrate applications, sweeteners such as sucralose and Acesulfume-K work better in the formulation process than aspartame, as both are more resistant to heat and acid changes.
In general, when formulating with soy protein, we need to understand the physical and chemical properties of the ingredient including dispersibility, water absorption, solubility, viscosity, gelation and emulsion capacity. Depending on the time and stage, these properties could be innate or inactive in your product formulation or production process.
When looking at the formulation of dry-blended powered beverages, low-acid beverages and high-acid beverages, all require different attention to mouthfeel, viscosity, dispersibilty, density and more. Dry blends: For a dry-blended product, the most important elements of formulation include mouthfeel, viscosity, dispersibility and density of the product. Soy protein is slightly different from dairy protein, as it requires more sheer energy and more time to be reconstituted into a solution. However, with a dry-blended product that contains soy protein, the producer doesn?t have the luxury of more energy and more time. Therefore, producers may use hydrocolloids to considerably improve the mouthfeel of a dry-blended beverage.
Generally, soy protein has a higher viscosity than dairy proteins. Therefore, for the powder to disperse in the solution better ? be it in water, milk or juice—producers may use an agglomerated product. However, cost associated with using agglomeration is high. Among other things, agglomeration decreases the bulk density of the product. This directly affects product elements such as packaging, which is extremely costly for the supplier to modify. Although very viable, most manufacturers avoid using agglomeration if possible.
Low acid: Different from dry-blended beverages, manufacturers that produce low-acid beverages, such as soymilk, concentrate on colour, dispersability, hydration, stabilisation, the buffering capacity and viscosity in formulation. Because consumers often compare or reference low-acid beverages with milk, emulsion is important, especially when the formulation uses little fat ? the higher the fat content, the better the emulsion. The comparison between the low-acid beverage and milk can present a challenge for the formulator.
Hydrating a soy protein requires extra care. Soy protein needs more time, more energy and higher temperatures to hydrate. And to stabilise soy protein, the formulator needs to use not only a stabiliser but also a buffering system. Successful rehydration also depends on the ingredient and the quality of the processing water. Therefore, many processors use dionised water, as its high quality makes it easier to use in formulation.
In addition, most liquid beverages require homogenisation. Soy protein generally is very heat stable, but for the long-shelf-life products, microbiological purity is critical.
Hydration also is extremely important. The correct rehydration process for soy protein is as follows.
- Disperse the powder, or wet it.
- ?Swell? the soy protein using heat and mechanical agitation.
- Dissolve it into a dispersible solution.
If this process proceeds too quickly, the temperature is too cold, or there isn?t proper agitation, the formulator is left with a non-dispersed protein—a lump of protein, if you will. If this occurs, the producer will have a finished product that lacks functionality and, therefore, he will not have produced a stable, palatable product.
As far as the solubility of soy protein, it decreases as the ionic strength or salt contained in the formulation increases. Without any salt, almost 90 per cent of isolated soy protein is dispersible in the solution. However, if you increase the ionic concentration to 0.10, the dispersability of isolated soy protein drops to 60 per cent.
As mentioned earlier, water quality is a key factor in the functionality of the solution. Specifically, calcium and magnesium are the two key divalent ions that producers want to avoid in the water when hydrating soy protein.
Emulsification is very important for homogeneity. In the case of a neutral beverage, protein with a higher emulsion capacity (grams of fat per millilitre of protein that a solution can encapsulate) is the best choice to use in formulation.
High acid: The V8 Splash Smoothie is a high-acid beverage that is becoming increasingly popular for consumers. Flavour, colour and the stabiliser system are even more important for these types of beverages than in other beverages. Interestingly, soy protein is very compatible with the fruit flavours generally found in these high-acid beverages. In fact, soy protein in general has less of a ?cooked? note than dairy protein, which means soy lends itself well to these types of flavours.
As far as colour is concerned, the vitamin and mineral fortification of these products, such as adding vitamin C, may negatively affect the colour of the end product. Therefore, producers should keep a close eye on colour but also proactively work with vitamin and mineral providers to ensure that the colour of the end product is correct.
With high-acid beverages, the stabiliser system also is key because, in using soy protein, producers technically are working against nature during formulation. In general, protein is not soluble in an acid environment. Therefore, the stabiliser system must be able to suspend the protein without sediment.
Without further processing, the typical isoelectric point for soy protein is pH 4.5, which makes it less soluble than more positively charged ingredients. Formulators should check to make sure soy protein ingredients manufacturers can further process the soy to an isoelectric point of pH 2.0—which would greatly improve solubility.
Homogenisation is always recommended in acid-beverage formulations. And because most high-acid beverages use juice as a main ingredient, the consumer expects the beverage to look, feel and taste like regular juice. Again, this comparison is a hurdle formulators must overcome to produce a successful high-acid beverage product.
Although each beverage formulation finds in soy both positive attributes as well as challenges to work around, the future of soy-ingredient formulation leaves me with a lot of optimism about the next advances in formulation. Through technology and key learnings, leading companies will continue to exceed the expectations of their customers and ultimately, of the end consumer by providing convenient, everyday foods that taste incredible and have the added health benefits of soy protein.
Jimbin Mai, PhD, is a director of applied sciences at The Solae Company. Respond: [email protected]
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