Article: Starches and Gums in Sauces and Dressings -- April 2008
April 1, 2008
Sauces and dressings are key components of a dish--they complement the main ingredients of meat or vegetables. A sauce will contribute to the success or failure of a complex meal. People eat salad for the dressing. Most commercial sauces and dressings start as recipes that are then scaled up by a food scientist to full production. A sauce must have the correct viscosity to look attractive and stay with the food with which it is to be consumed, but not clump. Consumers want a dressing that will pour out of the bottle onto the salad, but not run to the bottom of the bowl. Beyond the esthetics, the sauce must survive the processing requirements--the temperature, shear and pressure changes that it will experience from blending to consumption. Plus, there may be label considerations, like natural or organic. Starches and gums control the water to make the sauce or dressing a successful product. Starches are traditionally the most popular polysaccharide for this purpose and are used at the 2-5% level. However, gums are also effective carbohydrate-based ingredients, which are used at lower levels near 1%.
Sauces can be sold wet or dry, refrigerated or frozen, alone or as part of a complete dish (see sidebar “Savory Sauces,” which describes the classic culinary definitions of a sauce). These formulations are simply bases to be modified. Besides the savory sauces, there are sweet ones--like caramel, chocolate or fruit preparations. Chefs are continuously pushing the boundaries to make a sauce that is unique and distinctive for their needs--such as a lighter sauce or glaze, or combining sweet and savory. As well as adding flavor, many frozen meals have a sauce to enhance the moistness, which prevents the meat or vegetable from becoming too dry during heating. A sauce can assist in making the product have an ethnic feel, based on its flavor and texture. For example, stir-fry meals traditionally have a corn starch-thickened soy sauce.
The word “dressing” brings to mind salad dressings or an accompaniment to vegetables, although they can be used on sandwiches, as marinades or in any other situation where moistness and flavor are desired. Dressings are either spoonable or pourable, with roughly equal portions of oil and water--with vinegar, spices and flavorings added. Some dressings are creamy, some are not, and most are sold ready-to-eat, although dry mixes are available. Mayonnaise (which has a standard of identity) and similar emulsion products are also usually classified as salad dressings. Like sauces, unique ingredients in different combinations are creating new flavors and textures.
Choosing a ThickenerPicking one or two of the many polysaccharides available to increase viscosity is a daunting task. Working with suppliers is essential, and the more information they have about the formulation, the better able they are to assist in product development. Looking at websites is simply overwhelming--a knowledgeable technical service representative can assist in narrowing down the options. Cost is often a key driver in decision making. Typically, starches are less expensive and are used at higher levels than hydrocolloids. However, starches have functional limitations. In many situations, there are synergies between starches and gums, to make the choice even more complicated. Many functions of the polysaccharide need to be considered.
For example, there is the function of the thickener that will provide the sauce characteristics desired. How thick? Can it be cut? What is the pH? Does it need to pour at cold temperature (i.e., salad dressing out of a fridge), or will it be applied hot? What kind of body or viscosity is needed? Will it spread on toast or pour over ice cream--or both, as some new fruit preparations will do? Will the sauce be whipped, and thus, is aeration a consideration? What foods will be next to it? Is the sauce to be used in a sandwich that has a low-moisture coating--one that needs to stay dry? Will it be used on a high-moisture meat product, one from which it could pick up water? Is its appearance opaque or transparent? Does it provide cling or suspend solids? These are just a few of the issues that need consideration.
The thickener must also be able to withstand the rigors of the environments it will encounter. How is the sauce manufactured? What kind of equipment will be used to blend the ingredients? Will it be heated or cooked? Pasteurized or sterilized (i.e., retorted, hot-filled, UHT) and for how long, and under what conditions? Will the sauce be pumped? Homogenized? What viscosity will the equipment handle? Is the product frozen, shelf-stable or refrigerated? How will the consumer or foodservice establishment heat and use this product? Microwave or boil-in-bag? Will it need to sit at serving temperature for a period of time? Again, the options are many, so knowing the parameters is critical to picking the best thickener.
Labeling is another factor that cannot be overlooked. If the product is to be sold in Europe, then it must be GMO-free. Natural, organic and added fiber are other “buzz words” that marketing may want on the packaging; a religious designation may need to be considered.
The ChemistryWater is a simple molecule of hydrogen and oxygen, with manageable properties. Polysaccharides are large (many glycosyl units long) molecules that can hydrogen bond with water. Hydrocolloid is a term meaning “molecules that form colloids in water.” Gums are generally thought of synonymously with the term hydrocolloid; however, starch and pectin can be put under that same classification. Gums are also considered water-soluble polysaccharides--starch does not fit in that category.
When polysaccharides are distributed in water, they will bind to the water, and with each other, to set up a network in which the rest of the ingredients/molecules of the aqueous phase are dispersed. The exact nature of this network affects the structure of the sauce or dressing by controlling the water and the viscosity. Each carbohydrate (starch or gum) has its own structure and behavior. Understanding the chemistry of the polysaccharide, and how it reacts in different environments, helps determine the ingredients that will deliver the characteristics needed in the sauce or dressing.
StarchThe sources of starch are fairly simple: grain (wheat, barley, oats, corn [maize]) or tuber (tapioca, potato). All starch is composed of glucose monomers linked together with alpha-1-4 bonds. Nature packs the linear amylose and branched amylopectin together in the granule, as an energy source for a new plant. When these granules encounter water and heat, the granule expands, and the molecules bind water, which thickens the fluid. The rate of heating, level of agitation and the other ingredients in the food that compete for water, etc., determine the final characteristics of the sauce. In most situations, native starches will not meet the needs of the food formulator, because the viscosity developed will be broken down by disruption of the starch granules and the network set up by the molecules. The starch industry has developed hundreds of modified starches that can be pumped, heated, frozen, stirred and generally abused and still give the viscosity and appearance in the sauce or dressing. Some of these starches will be cook-up, which works well with sauces, since most are heated at some point.
The types of starches, and the terms used to describe them, are broad and differ with each starch company. Individual web sites provide information for that company--the chemistry of their product line and which ingredients are best for different applications. In general, the starch granules are either chemically or physically modified. Examples of chemical modification include cross-linking between starch chains or substitution, where side-chain composition is added. The starch molecules can become an emulsifier, with the addition of lipophilic components. Acid modification is another type of chemical modification. Physical modification can also be done, where the starch molecules are subjected to different forms of hydration, drying and heat treatment. These changes result in cold water-swelling or instant starches--they have different properties, but both will increase viscosity upon hydration, without heating. This is useful for dressing formulations that are not cooked. Dressings have a low pH, typically, and the acid will hydrolyze some starches, making them ineffective thickeners, so choosing the correct modified starch will be important.
Besides viscosity, starches influence other characteristics of sauces and dressings. The appearance can change, depending on the starch; corn starch gives a more translucent solution vs. wheat starch, which will be more opaque. Plus, dressings are stored in the refrigerator after opening, so a desirable viscosity at cooler temperatures is also important. The flavor of the native starch may be of little importance--overall, starches have a minimal flavor profile, especially when compared to the intensity of the spices or seasonings used in a salad dressing or sauce. Some starches are available that will enhance the flavor system. Dressings often have a high fat content, so emulsification may be a function of a thickener. Conversely, one may want to remove the oil to make a healthier product. Starches specifically modified to duplicate the mouthfeel, appearance and texture of fat are available.
HydrocolloidsHydrocolloids (or gums) are a group of polysaccharides from many different sources, with the common function of being able to structure water. Hydrocolloid gums are far from interchangeable in formulas, due to properties ranging from pH stability to viscosity. The chart “Application of Gums in Salad Dressings, Sauces and Relishes” provides a starting point to their usage, although formulas can benefit from exploring alternatives.
For example, xanthan gum has the added advantage of being soluble in cold water and is of natural origin. Methylcellulose has the unique property of becoming thicker as the temperature increases. Carrageenans are a group that can interact with other gums; some forms are thermoreversible gelling agents. Locust bean is a gum that gels with kappa-carrageenan. Guar is useful for instant viscosity development at room temperature. Gum Arabic (also called gum acacia) has a high solubility. Alginates come in many forms and are useful at cold temperatures.
Other gums such as agar, fenugreek, ghatti, karaya, konjac, tara and tragacanth are also available, providing nearly 20 options from which to choose. For added value, gum companies have developed their own proprietary blends for specific applications. These blends have unique properties and impart specific characteristics to food formulations or assist in processing and reheating.
The traditional chef method of sauce preparation serves as a basis for the food scientist to duplicate, using the range of ingredients available to give the texture, consistency and flavor required. Also, the tolerance to production and preparation (reheating with convection, conduction or microwave oven, or reconstituting a dry mix) must be considered when choosing a polysaccharide to manage the water. Dressings have different demands on their formulations than sauces, but the choice of thickener is equally important. The task of the formulator is to be able to manage the chemistry, while meeting all the needs of the sauce or dressing. pf
SIDEBARBéchamel is a standard white sauce, made with milk, added to a flour and fat roux and heated gently until the desired consistency is achieved. Veloute is similar to a béchamel, with the use of a white (chicken, veal or fish) stock, instead of milk.
Espagnole is a sauce made with brown (usually beef) stock added to a brown roux. A mirepoix (diced onions, celery and carrots) and tomato puree may also be added. A brown roux is a standard roux that has been sautéed to turn brown and develop additional flavor. Tomato is a sauce based on cooked tomatoes.
Although these are the classic four types of sauces, the fun for a chef and formulator is that there are many options for each ingredient! Plus, any ingredient can be added to make the sauce distinctive. Pick a cheese to add to a béchamelsauce. Wine works nicely with all the sauces, if that flavor is desired. Choose an herb or spice to add color and flavor to the sauce. Add texture with fruit or vegetable options in an espagnole. A variety of options exist for tomato-based sauces, from a classic marinara to barbecue.