Food Product Design: Design Elements - January 2001 - Home-Style Soup

By Charlie Baggs
Contributing Editor

On a cold day when the chill reaches your bones, you always can count on a good bowl of homemade soup to warm your soul. The perfect soup steams from the bowl to tantalize with its aromatics and puts family and guests into a receptive mood for the remainder of the menu.

The purpose of a dinner's soup course is twofold: first to stimulate the appetite and second to nourish the body. "Some light soups are more like an appetizer when a heavy soup or stew is a main course," says Chef Louis P. De Gouy, author of "The Gold Cook Book." He says, "They can both be home-style. Perhaps the best test for a chef is to choose the soup that truly complements the meal." So choose your soup wisely and complement your soup with logical, nutritious and delicious ideas.

From home to the plant
"Homemade soups" are made from scratch and require time and a kitchen. "Home-style soup" replicates homemade soup and is manufactured and prepared for convenience. It's not easy to replace the "simmered-all-day aroma" of homemade soup, but the soup manufacturer has several options, each with advantages and disadvantages. To achieve a home-style soup, a manufacturer must control ingredient changes and aim for a pre-determined goal - a gold standard.

The many different forms - retorted jar or can, frozen pouch or dry mix - provide convenience and functionality. For example, a dehydrated product is less expensive to ship free from water weight, but sacrifices freshness and sometimes ingredient quality. Frozen soups have high distribution costs, although quality can be excellent. Thermal processing of retort products hinders quality. Refrigerated soup has a much more limited shelf life than others, but encompasses superb quality.

Merging technology with a culinary twist to manufacture home-style soups is evolving. So develop a focused team that is determined to challenge all technical and culinary boundaries for a marketable product that tastes good. Good technique plus culinary sophistication will enhance any manufacturing process.

In the beginning
"Brown stock home manner - cut up 2 lbs. of shin or neck of beef; break 1 lb. of knuckle of veal into small pieces (about 3 or 4 lbs. of bones all together); cover with cold water (about 8 quarts), add 1 tablespoon of salt, and let stand for an hour, then bring gently to the boiling point, skimming the scum as it rises. When quite clear, add 2 carrots, scraped and cut into inch pieces, 2 medium-sized white turnips peeled and quartered, 1 stalk of celery, well-washed and cut into inch pieces, a bouquet garni composed of two bay leaves, 1 large sprig of thyme, 12 sprigs of fresh parsley, all tied together with kitchen thread, add also 15 whole pepper corns, gently bruised…." (from the "The Gold Cook Book," 1947.)

This labor-intensive process is no longer economical or realistic. In this fast-paced world, who has the time? (In addition, it is almost impossible to get your hands on the bones.)

"One of the long-held beliefs about soups is that time is a crucial ingredient," says Jonathan Crossland, corporate chef, Woodland Foods, Gurnee, IL. "I no doubt agree with this, however store shelves are filled with 'instantized' soups. The popularity and success of these products is not because consumers are willing to sacrifice the depth of flavor associated with slow-cooked soup. In fact, the contrary is true. The desire for convenience soups has challenged ingredient and flavor manufactures to introduce new products that mimic and build on that homemade perception. It is important to note that the term 'homemade' is much more than a catchphrase for the marketing department."

Home-style means something other than insipid, run-of-the mill products. Michael McGrath, president & CEO of Country Gourmet Foods, Weston, CT says, "variety is important to the consumer that is interested in home-style soup. Country Gourmet Foods is targeted to market 25 soup varieties. It is equally important to manufacture a soup that delivers a taste that the consumer will remember as craveable and will purchase again."

Taking stock
Stock is the foundation of all meat, vegetable and fish soups. Therefore, it is of utmost importance to formulate the most economical and complete form of stock when preparing a soup. The mirepoix can vary from onion, carrot and celery to leeks, parsnip and mushrooms. Traditionally, fresh uncooked meat works best when making a bouillon or broth, and roasted cracked bones work well for a stock. The bones contribute gelatin, roasted flavor and body. Today, the utilization of bases is the most likely stock-preparing method. Meat flavors come in all forms from paste, dried and liquid. The applications are limited, so you have to choose the best method for a specific soup preparation.

Add ingredients to enhance stock's savory flavor. For example, mushrooms give an earthy flavor, mirepoix provides a balanced vegetable note and caramelized onions lend sweetness. These characteristics are difficult to maintain in all types of manufacturing.

Technical focus
So, how do you simulate a homemade soup in a manufacturing process? How do you control the viscosity from filling to service? How do you maintain the proper color, particulate, flavor and identity of a soup? The more processing a food encounters, the more technology plays an important role.

Understanding the function of gums, starches, flavor enhancers and other ingredients and the effects of processing on food is key to the manufacture of a good home-style soup. Processing food with heat, shear, time and pressure all destroy the freshness. Merging technology with culinary expertise produces new manufacturing possibilities.

Anytime you process food, the structure, flavor, texture and chemical make-up can be changed. The goal is to control the changes to promote a better product for the consumer.
Developing the gold-standard recipe in product development is critical. The development team must agree on a flavor, color, texture, particulate, consistency and quality before work begins. The label requirements can determine what flavor systems may be used or what ingredients are prohibited. Begin with a flavoring system, such as a stock with mirepoix, as a foundation; then build on it with particulates, flavor enhancers and aromatics.

During product development, starch, gum, flavor enhancers, fresh produce, meat, stock, aromatics and spices all can play a role in matching the gold standard. Starches and gums aid processing and flowability, and can mimic fat and provide texture and mouthfeel. In most cases, starches are more economical than a vegetable puree. But, the finished product always should be tasted for authenticity and flavor.

Suppliers offer a wide assortment of starches, including rice, tapioca, wheat and potato, all of which provide specific results. Starch's properties can be chemically modified with acid, cross-linking or substitution to fine-tune its capabilities. Starch's moisture content ranges from 6% to 12%, depending if it's a pregelatinized, instant-granular type or a traditional cook-up starch. Potato and tapioca starches resist oxidation because of their low lipid and protein contents. Amylose-containing starches, such as tapioca, provide opacity, while potato starch provides clarity without gloss.

"Cream soups and pureed vegetable soups may use similar starches for their thickening depending on the type of texture wanted," says Michael Augustine, director of food ingredient applications, A.E. Staley Manufacturing Co., part of the Tate and Lyle Group, Decatur, IL. "There are companies that will use a tapioca starch to contribute a very bland, creamy quality to their soups, especially the cream-style soups. And others just use traditional waxy starches as the primary thickener and may use some form of a common corn starch to provide a heavier body or gelling character."

Gums can be used in conjunction with starches to provide texture, viscosity and suspend solids. Temperature and dispersion method primarily affect gum selection. While many gums require high-shear mixing, which, operationally, isn't always possible, there are gums for all sorts of shear.

Proteins also may add viscosity, fortification and fat replacement. They exhibit both hydrophilic and hydrophobic properties, so they can bind water and, if fat is present, emulsify, too. Soy and dairy proteins are commonly used. Lecithin also can function as an emulsifier.

Color can be difficult to duplicate, due to manufacturing processes vs. kitchen. Extra "browning" can be supplied by caramel color for darker soups. This color can complement a roasted flavor and give more visual appeal. Cooking tends to deteriorate the green colors in vegetables such as spinach or parsley. Tomato is excellent for establishing a red color, but if overcooked, the color becomes brownish.

Flavors and enhancers accentuate the flavors of more expensive ingredients or simulate a cooking process, such as grilling or roasting. Produce can contribute viscosity, sweet flavors and color. Meat and stock provide color, flavor and nutrition. In addition, the aromatics and spices are considered the icing on the cake.

There are several ways to add savory flavor to a home-style soup, says Helen Bauch, president, Food Smarts, Fallbrook, CA: "The umami taste sensation can be increased by flavor enhancers such as soy sauce, protein hydrolysates, glutamates and nucleotides. Smoked, grilled and roasted flavors can add tremendous depth to the flavor profile. Some compounded sauces can add a savory background flavor such as barbecue sauce, Worcestershire sauce or sausage seasoning. Finally, cheese-flavor notes are very effective where appropriate, for instance, in creamy soups."

Frozen assets
Freezing soup is one of the best ways to preserve its identity; the ingredients maintain integrity, color, nutrition and flavor comparable to homemade. However, building frozen soups presents some unique challenges, including distribution and maintaining tissue integrity of produce and meat.

"Frozen soups are preserved by reducing the temperature until well below the freezing point of water, at which point they may be kept for many months safely," says Peter Clark, Ph.D., consulting food engineer, Oak Park, IL. "Ingredients for frozen soups are similar to those used for canned soups, that is raw, fresh or frozen, partially prepared (precooked meat, for example), bases, spices and flavors. Typically, frozen soups are prepared as a complete formula and filled into trays for foodservice or other containers for consumer sale. They may be heated during mixing to dissolve ingredients, gelatinize starch and remove air. If they are heated, they may be partially cooled before filling in order to reduce the cost of freezing, but there can then be some risk of spoilage if this is not done efficiently."

Freezing can be done with liquefied gases (carbon dioxide or nitrogen), known as cryogenic freezing, or with mechanical refrigeration, using ammonia or other chemical refrigerants. "Cryogenic freezing is faster and the equipment is less expensive, but the gases are an ongoing expense," says Clark. "Mechanical refrigeration is more capital-intensive, but only requires purchased electricity. Packaging for frozen foods can be less expensive than cans or jars."

A frozen soup travels many paths and unfortunately will go through many freeze/thaw cycles that adversely affect quality. The temperature fluctuations cause ice crystals to form, which promotes undesirable flavor and texture through dehydration, moisture migration, structural breakdown and syneresis.
The temperature fluctuation can be minimal and does not need to rise above 32°F to wreak havoc. Water in a food system carries solutes that depress the freezing point. As the temperature drops and ice crystals form, the solutes become more concentrated. This further depresses the freezing point. Consequently, some water always remains liquid.

Large ice crystals form during freeze/thaw cycling that can rupture cell walls and break molecular structures. Imagine the adverse effect on a delicate cell wall of a vegetable - destruction spelled all over it. The larger the ice crystals, the greater the potential damage.

The freezing point temperature (Tf) is based on the molecular weight of the solutes. This can be figured out with a mean of all ingredients. Low molecular weight lowers Tf, for instance, salt lowers freezing temperature. Therefore, the development team can adjust the molecular weight and still maintain flavor. But this process needs to be tested to ensure the desired results and gold-standard flavor are achieved.

Water activity (Aw) and temperature both promote an atmosphere for enzymatic breakdown. Vegetables require blanching to deactivate the enzymes in frozen products if they are not otherwise cooked.

Meat, though expensive, serves as a soup's identifying flavor component. Therefore, maintaining quality is essential for an excellent product. Phosphates can be added to meat to strengthen the protein to maintain integrity.

In soup, the goal is to bind the free water to prevent condensation, migration or syneresis. Hydrocolloid starches and gums help control crystal growth because they bind water and prevent it from coalescing into larger ice crystals. Some hydrocolloids that hinder water crystallization are locust bean gum, guar gum, carboxymethylcellulose (CMC) and carrageenan. However, too many hydrocolloids cause syneresis, squeezing the water right out of the product, so it is best to be conservative in the design process.

To assure quality and freeze/thaw stability, freeze the product quickly, which limits Aw and forms small crystals, then deliver it to the consumer with as few temperature fluctuations as possible. This is nearly impossible, but is essential to mantain quality.

Can it be canned?
Everyone has at least one can of soup in the pantry. Advantages of retorted soup include shelf stability and ease of use for the consumer.

Commercial sterilization is driven by elevated heat under pressure. Both heat and pressure break down cell structure and change the identity of the particulates. Therefore, there is much to gain from a process that is designed to preserve flavor and product integrity. The retort trilogy used here is as follows: produce a soup that is designed for quality, sterilization/safety and economics.

Sterilization/safety standards are met by paying close attention to details. In an article entitled, "In the Can, a Look at Retorting" from the August 1994 issue of Food Product Design, Jenny Scott, chief microbiologist of the processing technology and microbiology center of the National Food Processors Association, Washington, D.C., describes commercial sterilization as "an inactivation of organisms of significance to both public health and spoilage under normal conditions of storage. Most thermal processes are designed to inactivate spoilage organisms with the understanding that they will be more resistant than C. botulinum. In most cases, you're looking at Clostridium sporogenes."

Several factors affect the heat transfer and time of cooking necessary to commercially sterilize: the manufacturing process and equipment design; shape and size of container; viscosity of product; size and amount of particulate; and headspace. Retorting methods include still, continuous, batch and hydrostatic. Certain products are best-suited for each method. The viscosity, size of particulate, headspace and pH are all variables that affect process. More information about determining the heat treatment required can be found in Food Product Design's, "In the Can: A Look at Retorting." Product designers can rely on thermocouple temperature readings or microbiological spore count to assess product sterility. Take the conservative approach and use both for extra safety measures. For example, pasta used in a soup may stick together and create a hazard because sufficient heat may not penetrate to sterilize the center of the pasta clump.

Retorting can adversely affect product-quality issues, such as color and vitamin retention. Vitamin C and thiamine degrade under heat. Chlorophyll and lycopene pigments discolor when exposed to excessive heat, making it difficult to maintain the true green of parsley in a retort soup. High or low pH also will affect color. When using a clear glass jar instead of a can, some colors will fade with exposure to light.

Depending on the method of manufacture, vegetables for retorted soups may not require blanching. It may help heat up the product when incorporating vegetables directly from blanching. A blanched product also is easier to handle when filling a container.

"The soups are usually formulated from raw, fresh or frozen ingredients, including root vegetables (potatoes, carrots, turnips and onions), celery, meats, pasta, beans, rice, various stocks and bases (tomato paste, chicken stock, beef stock) and spices and flavors," says Clark. "Frozen ingredients need to be thawed and, perhaps, cut to size. Fresh ingredients need to be cleaned, peeled and sized. Pasta, beans and rice may need to be hydrated, though fresh pasta can be used directly. Meats may need to be cooked. Stocks can be purchased as powders or pastes, or prepared by cooking bones and meat scraps. Soups can be filled in one or more steps; each material may need to be mixed in a separate kettle. For example, meats may be mixed with a thick starch to permit accurate portioning. Traditionally, kettle mixes are heated to dissolve ingredients, gelatinize starch and remove air. Thermal processing can reduce the impact of flavors and spices, so larger quantities may be required than would be used in a freshly prepared soup."

The process used can make a big difference when making a soup that's considered home-style. A multiple-stage filling process greatly affects the quality. Also, cooking order can play a role; items that cook faster or deteriorate from heat and mechanical processing should be added near the end of the pre-cooking and batching process.

Choosing the correct starch can help preserve quality. "Modified food starches that are used in retorted soup applications can play several roles," John J. Mitolo, technical service manager, National Starch & Chemical Company, Bridgewater, NJ, points out. "Starches can be used to aid in filling viscosity to suspend particulates only, not contributing to the soup's finished viscosity. Modified starches can also be used that display a low initial viscosity profile to maximize heat penetration, yet provide finished product viscosity. The tolerance to heat that is required from a starch during retorting due to high process temperatures can be achieved by using highly cross-linked starches."

A broth-based soup made at home has enough viscosity for mouthfeel, but not enough for commercial production. This style might require formulation with a filling starch to develop enough viscosity to suspend the soup's particulates during filling. "This allows the cans to be filled to proper weight with the correct distribution of particulates, such as vegetables or meat," says Augustine. "These starches have the ability to hold up to temperatures of about 180°F for up to a half hour. They are then designed, because of their modification, to breakdown during retorting so that they contribute no viscosity in the finished product."

Soup in a box
Aseptic soup processing has formulation limitations, but the packaging is very user-friendly and easy to transport. The lightweight, minimal packaging has many advantages. The size can vary depending on product and convenience for the consumer. The square boxes are easy to stack and store since there is no wasted space from rounded corners as with cans.

In aseptic packaging, the product is sterilized outside the package. It typically uses a HTST (high temperature short time) process that creates less stress on a product - minimally processed food has a better chance of maintaining integrity. However, the filling procedure still can stress the product and the other deterioration factors still are in play. For example, particulate size and colorful ingredients all can be adversely affected.

Various heat-transfer methods used with aseptic packaging include plate sterilization, steam injection, steam infusion and tube-to-tube. The processing rate is between 10 gal. to 30 gal. per minute (gpm) for aseptic, compared to a rate nearly double for retort processing, according to Clark.

Hot hydrogen-peroxide vapor sterilizes the cartons in the filler. After evaporating the vapor with sterile air, the cartons are immediately filled with a sterilized, cooled product. Timing is everything; the longer the product is maintained at an elevated temperature, the more it breaks down and changes.

It's easier to use this technique for broths and pureed soup. The particulate size is a limiting factor, although the size that can be processed is increasing as technology is advanced. In 1985, an 8-mm particulate was the limit, but now it's closer to 16 mm. With the advancements in pH, variety and particulate size, aseptic packaging will continue to be valuable. (Contact the Center for Advanced Processing and Packaging Studies (CAPPS), Ohio State University, Columbus, for additional information.)

Just add water
Dehydrated soup is convenient, easy-to-store, shelf-stable and user-friendly. However, some fresh home-style properties are sacrificed. For example, fresh vegetables are not an option. Viscosity is controlled with starch and gums rather than vegetables and natural gelatins from homemade stocks. Flavors are typically attached to carriers for dispersion and shelf life; oil is often used to prevent dusting during manufacturing.

"Dry soups use almost entirely purchased ingredients, which require little preparation, " says Clark. "For example, meats are often freeze-dried, fats may be powdered and vegetables are dehydrated. Mixing must be gentle to avoid damaging the fragile dried particulates. If fat is to be incorporated, high-intensity agitation may be required. Inexpensive packaging, such as foil pouches, can be used, and secondary packaging is minor." Dehydrated-soup manufacturing has common ingredients that have multiple functions. For example, stabilizers that provide structure also act as a carrier or bulking agent to aid filling, or simulate the appearance or mouthfeel of ingredients such as vegetable puree or fat.

According to Augustine, instant soups often require agglomerated starches "that allow for excellent dispersibilty in hot water. A non-agglomerated instant starch would hydrate too quickly in hot water and form 'fish eyes' that limit their effectiveness. Agglomeration allows for slower and even hydration of the instant starch in hot water."

Urn water at 190°F may be the only heat source, requiring a quick-hydrating starch or gum. Some starches need higher heating for longer periods before they are activated. "Dehydrated soups can take advantage of the dispersion and hydration properties of instant- and cold-water-swelling starches," says Mitolo. "Soups that are reconstituted by adding hot water or are microwaved require specific functionality from starches. Soups that require hot water can use easy-to-hydrate cook-up starches, while microwave soups can use instant or cold-water-swelling starches."
It is important to know the temperature at which the soup will be reconstituted. If the customer has access to a stove, then heat is not a problem. But with a quick soup microwaved during lunch at the office, the control of heat is somewhat limited; therefore, a lower activation temperature is necessary. Some instant starches will thicken at minimal temperatures.

Viscosity changes depend on the gelatinization characteristics of the starch used. High-amylose cornstarch needs a relatively long period of exposure to high heat, but potato starch can gelatinize at temperatures below boiling. The potato starch molecule is different in size and shape, and absorbs water more rapidly at lower temperatures.

A pregelatinized starch has been hydrated to its gelatinization temperature, then dried. This process expedites the rehydration process and lowers the temperature required to provide viscosity. Too high of heat can break down a starch's molecular structure, so again, temperature control is critical.

Flavor systems must be in dry form. "Savory flavor can be enhanced with the addition of natural dairy flavors, most available in powdered form," says Bill Buhler, president, ButterBuds Food Ingredients, Racine, WI. "They can contain free fatty acids and other flavor precursors that complement flavor in meats." Surprisingly, the same ingredients can mask bitterness and off-notes that come from meat trimmings or powders. "The idea is to use a tiny amount - say 0.25% to 0.50% - to get the enhancing effect but not enough to contribute dairy taste," says Adam Small, applications scientist, Butter Buds. "Since the correct usage level is critical, I usually suggest starting with one of our medium-strength products. Slightly higher levels can be used to contribute richness, flavor and mouthfeel in cream- or cheese-based soups where cost can be saved while adding insignificant fat."

Because of the use of dehydrated materials, some dry soup blends would amount to such a small quantity that they could blow away if you sneezed. Carriers fill in empty space and make filling easier. Maltodextrin is a common filler that also adds viscosity.

Pasta in a dry mix should be packaged separately if the moisture is higher than the mix. The moisture can cause clumping and improper rehydration. Instant or precooked pasta often is used, especially for products rehydrated without boiling.
Rice also can be purchased with different rehydration times and temperatures. Cooking time and moisture will determine which product best fits a soup formula. The textures do change with instantized rice - although manufacturers are coming closer to a traditionally cooked texture.

Don't forget to supply the end user with hints to use fresh ingredients that improve the eating experience. For example, to take a chicken noodle to the next level, garnish with chopped scallions and serve with good bread and butter. This is home-style!

Chilled today, hot tomorrow
Refrigerated soup is processed the least of all. Often, the foundation is a stock made from bones, mirepoix and bouquet garni. The culinary standards for a refrigerated soup can be as high as one can afford. Homemade-style stock, caramelization of vegetables, fresh produce and meat all cost money.

Chef Volker Frick, Kettle Cuisine, Inc., Chelsea, MA, states that he will only use the freshest, top-quality ingredients available. His manufacturing facility is located next to a produce market, and his ingredients are delivered fresh each day to produce varieties such as Vegetable Beef Barley, Chicken Summer Vegetable, Three Bean Chili, Thai Shrimp, Scallops and Zucchini and New England Clam Chowder, as well as three cold summer soups including Gazpacho, Caribbean Mango and Wild Fruit.

Frick produces an all-natural product with the freshest ingredients. Preserving the finest flavors and particulate integrity are critical. "I do not use anything I cannot say or spell," he says. This is not from a lack of knowledge, but a commitment to flavor and a desire to produce a truly home-style product.

To extend shelf life, the soup is vacuum-bagged to limit exposure to oxygen. The shelf life of this refrigerated product is then 22 to 35 days. This process depends on a very efficient distribution system and adherence to use-by dates to assure quality.

Culinary focus
Soup will always be a strong player because of its convenience, nutrition, variety, ease of storage and shelf stability.

Remember, the more processed a product is, the more it changes. The goal remains to control the changes and to manufacture a gold-standard recipe. Always use solid technique, limit processing and have a specific gold-standard flavor and identity to work towards. Merging technology with a culinary twist is necessary to manufacture home-style soups, with its many technical and culinary variables.

Develop a focused team that is determined to challenge all technical and culinary boundaries to produce a product that is marketable and tastes good. Good technique plus culinary sophistication will enhance any manufacturing process. "Think of the soup base as a canvas, an anchor, a background flavor against which the developer can arrange particulates, flavoring elements and garnishes to create an artistic-looking and palate-pleasing composition," says Bauch.

The bottom line with any soup is that it must be heated and served at the proper temperature, and served with dignity. According to my mentor and friend Arthur Avery, professor emeritus, Purdue University, West Lafayette, IN, like a good cup of coffee, most soups should be served at 190°F with the appropriate garnish, of course. So add a dimension of aroma and flavor by topping with freshly grated cheese, a chiffonade of basil, cracked black pepper or a drizzle of extra-virgin olive oil and enjoy.

Charlie Baggs, president and founder of Charlie Baggs, Inc., has been part of the food industry for more than 17 years. Having trained at the Culinary Institute of America, Hyde Park, NY, and Purdue University's Restaurant, Hotel, Institutional Management and Tourism, Lafayette, IN, Baggs now shares his expertise and creativity in culinary training, product concepts and recipe development with top food and ingredient manufacturers. Visit http://www.charliebaggsinc.com for more information.

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