Versatility and unique properties easily make starches the hardest working ingredients
Starches are an integral part of virtually every prepared food. As ingredients and macronutrients, these workhorses contribute to structure from their very inception in the plant and serve to nourish the plant (and its consumer) with a wide range of taste and textural variations.
Harvested from grain and turned into ingredients, these multi-faceted carbohydrates act as bulking, thickening, gelling, stabilizing, binding and coating agents—under even some of the harshest conditions associated with industrial manufacturing. Nature offers a seemingly endless variety of starches, and the bounty can be multiplied further via physical, chemical and enzymatic treatments to overcome any inherent deficiencies and expand their array of functionalities and health benefits.
Although made up of just two kinds of carbohydrate polymers—amylose and amylopectin—starches even from a single source can vary considerably in shape, size and properties. This accounts for a range of textures, tastes and functionalities unmatched by any other ingredient.
Versatility and unique properties have propelled starches into the integral landscape of every kind of prepared food. This includes the emerging landscape of prepared foods consisting of ready-to-eat (RTE) fresh foods that have, according to the consumer food and beverage research organization NPD Group, become a lifeline for supermarkets. Such stores have stolen customer visit numbers from restaurants and captured share from the meal and snacks market.
With such pervasiveness, it could be hard to imagine inroads for starches that have not already been well-trodden. But recent shifts in consumer demands and expectations have opened some key areas for product development using starches with unique properties.
A Fresh Approach
Functional starches are essential to the influx of fresh foods serving the consumer belief that they’re less processed and therefore, somehow “better for you.” This category continues to grow in popularity, and to align with the health and wellness goals of this market, many manufacturers are making RTE meal kits that do away with the necessity of preparation, yet still provide consumers the satisfaction and benefits of freshly prepared foods. (See “On the One Hand,” PF October 2015.)
Such products involve pre-portioned protein, sauce, vegetables and carbohydrates and often are distributed frozen for retailers to thaw and offer in refrigerated display cases. Critically, each node in the distribution chain involves a temperature change. The challenge is therefore to avoid any changes in texture, mouthfeel or even appearance of some foods along this chain. This is where starches come to the rescue.
“Fresh” food products, such as meat, poultry, seafood, deli products and prepared foods, face unique challenges in maintaining freshness attributes during frozen distribution, while in the retailer’s refrigerator, and upon consumer storage and freezing.
Repeated freeze/thaw, or improper refrigeration, especially disrupt the cellular structure of animal proteins, such as meat, poultry and seafood. The cells burst, releasing moisture (a process called “purge loss”), damaging the product’s texture. While phosphates historically have been used to retain moisture. Many manufacturers have recently been replacing these with modified food starches.
Modified food starches work well in such high-protein applications, because they have an inherent stability, process tolerance and an ability to control any release moisture without purge loss or damaging quality and texture. However, chemically modified starches increasingly are seen as a negative on the label.
Starches are modified by gelatinization, so as to make them easily soluble in cold water. Cool-water solubility is an important functional property in instant foods.
Cold-water soluble functional native starches swell instantly when rehydrated in cold water and make pastes with stable viscosities and freeze/thaw stabilities in comparison to their plain starch counterparts. Starch has come a long way from being regarded as a low-quality gruel to a functional ingredient.
Native starches, modified starches’ “cleaner” counterparts, traditionally have not been satisfactory substitutes for chemically modified food starches because of inconsistent quality and functionality, plus a generally low tolerance of harsh temperatures and high shear.
Functional native starches, such as waxy maize and waxy rice, however, are made up almost entirely of amylopectin, with superior water-holding capacity, and which have been processed physically for uniformity in size and structure. They therefore can match the functionality of modified starches and uphold optimum quality in finished products.
Many companies are turning to these native starches. St. Louis Bread Co.’s Panera Bread recently announced the chain of bakeries and restaurants are expecting as much as a 10% increase of prepared foods in the coming year.
This is against the backdrop of a 4% increase forecast for commercial foodservice traffic. Their processors turn to functional native starches to deliver on consumer expectations of “freshly made, premium” foods—while maintaining a steady bottom line.
This growing demand for premium prepared foods is driving exploration of food science-based tools and methods. Physical processing helps modulate the size and surface aspects of native starches, to create uniformity in their properties and widen their peak viscosity range. Annealing helps enhance the robustness of starches in the harshest of temperatures, pH and shear, and it smoothes their texture.
Because these starches have only been processed physically to develop the functionality of traditional modified starches, they may be labeled on the basis of their source, such as “corn starch” or “rice starch,” to meet clean-label criteria in industrial food preparation.
Meat Meets Starch
Luncheon loaves, roast beef, turkey breast, pork roasts, fish patties, surimi sticks, ham loaf and chicken—along with high-end pressed and shaped products such as duck and veal that in-store delis carry—rely on native functional starches more than ever.
Starches such as waxy maize help bind the moisture within the protein matrix in a heavily prepared deli meat product. The amylopectin in the waxy maize produces a gel with the water released from the muscle. In addition, this also builds a desirable mouthfeel, particularly when used in reduced-fat products.
From a bottom-line aspect, using these starches can also enhance the yield of processed meats, as well as improve their nutritional profile.
Cleanliness of a label, however, depends on the eyes of the beholder. Functional native starches in meat products—while perceived by some as a cleaner alternative to phosphate and modified starch—can still be off-putting to purists who want nothing but meat and spices in their meats.
Water plays a critical role in stews, thickened soups (e.g., dairy-based soups) and sauces, from the time the product is made, through storage and handling, all the way up to consumption. When frozen stews, soups or sauces thaw, water migrates, causing the item to separate.
Moreover, when gums are incorporated into these formulations, additional water is usually required. This, in turn, can require additional flavor and texture modifiers to make the sauce deliver on consumers’ flavor and texture expectations.
Functional native starches work hard in these products to prove health and good taste can co-exist. For example, RTE soups, sauces and condiments/dressings favored particularly for creaminess are getting a healthful makeover with waxy potato starch.
This form of potato starch is derived from potatoes bred, using traditional techniques, to contain more amylopectin than typical to standard potatoes. Potato amylopectin provides high-quality, creamy and indulgent textures in soups, dressings and sauces, and can allow up to 50% reduction in fat without breaking down during high-sheer processing.
All this, and the attractive cost-saving opportunities, make functional native starches popular for cook-up creamy powder mixes, as well. Their stability also works well with ultra-high temperature (UHT) processed soups and sauces suitable for reduced-calorie formulations.
Consumers reach for yogurt, and yogurt- or other dairy-based drinks (such as kefir and smoothies), not only for their functional health benefits but to refresh and recharge. These products, generally made by adding fruit juices and protein to a dairy base, also require the addition of acid to adjust the flavor and texture.
Fruit juices and acids, such as citric acid, lactic acid, fumaric acid or malic acid (the principal acid in many fruits and vegetables), acidify the product down to a pH of about 3.5 to 4.2.
This acidification can denature the proteins, i.e., causing whey to separate, and make the end-product turn watery due to syneresis. Stabilizers, such as pectins, carrageenan, xanthan and locust bean gum (LBG); and modified starches, including sodium carboxymethyl cellulose (CMC), that are effective at preventing the syneresis of acidified dairy drinks, are increasingly shunned by consumers, however.
Waxy maize and waxy potato starches, by matching the functionality of traditional modified starches in terms of shear, pH, process tolerance, viscosity, texture and shelf stability, can meet the needs of both consumers and manufacturers with “friendly” names that fit clean labels.
Starch granulation size and distribution are important characteristics, because they have a direct inﬂuence on material properties, such as reactivity, dissolution rate, suspension stability, delivery efﬁciency, texture, appearance, ﬂowability, viscosity, packing density and porosity. Physically modified, clean label starches can help control water migration and without gelling prevent the separation to give a smooth, homogeneous texture that leads the consumer into believing it was “just made.”
Moisture management is critical in refrigerated prepared foods containing pasta as a component. Traditional wheat pasta submerged in a sauce tends to absorb the liquid and become soft and mushy during extended refrigeration. The addition of resistant starch to the pasta can prevent this absorption and mushiness without affecting the pasta’s texture.
Starch granules’ size inﬂuences processing-relevant properties, such as gelatinization, water and flavor absorption; as well as solubility, and marketing/nutrition-related properties, such as digestion rate and nutritional value. Physical modifications help modulate the granular size of the starches and thereby, their rate of gelatinization and rate of digestion.
Gel clarity is an important functional property of thickeners in jams, soups and stews where clarity implies the absence of cheap filler starches. The repeated heating and cooling consumers often inflict on some of these foods can lead to a breakdown in clarity and color of the base and particulate ingredients.
No Grain Necessary
Starches offer a perceived low-tech (but high-potential) solution to address future food shortages by harvesting from roots, tubers, stems, and unripe fruits that are often not used for consumption by humans. Bananas (rich in starch) have, through thousands of years of hybridization, gained unique functional properties not found in other leading source of energy, such as corn, rice and wheat.
Physically modified native banana starches—labeled as “banana starch” in the ingredient list—function particularly well in high clear gel applications by sustaining the appropriate viscosity without becoming cloudy. The price differential in banana starches from modified starches makes them an even more attractive clean label ingredient. In infant formula, gelatinized rice starches are effective in enhancing viscosity.
Viscosity is an important aspect of infant formula, as the infant’s ability to swallow has typically not fully developed at the stage when infants typically begin formula feeding. The use of certain starch forms to help minimize regurgitation adds multiple benefits only a parent can truly appreciate.
That native banana starches have almost as much as 40% naturally occurring resistant starch makes them ideal for making consumer favorites, such as cookies, baked goods and snacks, popular alternatives for weight and blood sugar management, without the product taking on a cardboard-like texture. The recent Paleo diet craze has created a rush for applications—from Grab ‘em Snacks LLC’s banana flour chips; to Dempsey Bakery Co.’s banana chocolate chip cookies; to WEDO Entrepreneurs LLC’s flour for bakers to mix into their favorite recipes.
Navy bean flour and peanut flours are finding their way into bakery goods and snacks as a replacement of all or part of the egg and as an alternative to wheat. The starches of pulses and nuts offer a unique and sensual crispness that adds to the texture of baked goods without the need for additional fat.
Feeding the Microbiome
The popular perception of starchy foods as fattening and laden with empty calories stubbornly persists in some quarters. Increasingly, functional starches are changing that perception. This is especially true of starches that are fermentable, i.e., resistant to digestion in the stomach and small intestine.
Resistance to digestion is a valuable parameter from a nutritional point of view. Because resistant starches escape digestion in the upper digestive tract, they move into the lower g.i. tract to deliver some of the beneﬁts of insoluble and soluble ﬁbers, as well as unique health benefits.
Resistant starches are not digestible by the human body, but they are a feast for the various strains of bacteria that reside in the lower gut. Colon bacteria convert resistant starches into short-chain fatty acids, including butyrate, with beneficial effects on the colon and overall health. Resistant starches appear to increase butyrate production more when compared with other soluble fibers.
Reducing digestibility also reduces the calorie load, which means fewer calories are available for absorption. This means that, even without reducing the quantity of rice consumed, its calorie implications are reduced. This concept may be suitable for satiating pre-cooked and RTE rice products with the added benefits of dietary fiber and prebiotic effects—but without affecting taste or texture.
Foods rich in resistant starch can help consumers who fall short of their daily intake of fiber without changing the taste of their favorite staple food. While the intrinsic resistant starch content of grains such as corn, wheat, barley and rice can be increased using traditional breeding techniques, how the grains are cooked and cooled can also transform digestible starch. It does this via retrogradation (an ordered form of crystallization) into resistant starch, and significantly lower their glycemic response and caloric contribution.
At a recent meeting of the American Chemical Society, scientists reported as much as a 15-fold increase in the resistance starch content of rice subjected to extended simmering and oven-drying, along with the addition of coconut oil, and with no reversal with repeated reheating. The oil penetrates the starch granules during cooking to form indigestible hydrogen bonds with the amylose molecules and renders the starch resistant to digestion.
New discoveries about the complex nature of the human microbiome will continue to bring attention to the importance of what people eat. The human microbiome, which is the collection of microorganism that lives on and within the human body, is integral to human’s overall health, immune system function, metabolic processes and even mood.
Starches can be especially helpful in formulating frozen pre- and par-baked goods. For example, in the foodservice arena, most baked items, especially specialized or less called-for items such as gluten-free bread and rolls, rarely are made on premises. These typically are purchased in frozen formats for use when needed.
Freezing causes considerable physical and taste damage in the dough, even in baked or partially baked products. Formulators often resort to a combination of hydrocolloids to buffer the changes and protect the cell structure during freezing and thawing. However, the resulting products tend to be firmer than the original bread, with lower specific volume and harder crumb. These defects also are seen in gluten-containing breads made from frozen doughs. Additionally, gluten-free breads can tend to be gummy, due to ingredients used to compensate for the lack of gluten.
Joe O’Neill, an independent consultant with experience in naturally derived starches, notes that rice starches possess good stability for freeze/thaw, acid and sheer conditions, positioning them perfectly for use in frozen products and packaged sauces. Naturally gluten-free, rice starches can be used with or without gluten-containing starches.
O’Neill also points to the benefits of the neutral taste and color profiles of rice starches, and how these traits showcase the intrinsic attributes of the final product. Rice starches are increasing in popularity as a natural fat replacer, too. This is because their small granules, when gelatinized, mimic the full-bodied creamy mouthfeel of fats and lend creaminess to lower-fat versions of soups, sauces, fillings, dairy desserts and ready-made meals.
The growing demand for egg replacers, because of surging egg prices and the growing free-from market, offers another opportunity for starches. But the replacement of egg is a tall order, for eggs are a multi-faceted ingredient. Their functional properties range from aeration, binding, emulsification, coagulation and mouthfeel to create the expected and desired taste, texture and appearance of a range of products—including bakery, prepared meals and desserts. (See “Hard Boiled Crisis,” PF September 2015.)
Commercial egg replacers tend to be blends of gums, such as cellulose gums or sodium alginate; proteins such as potato and pulse proteins; and/or flours and starches from tapioca, corn, potato and pulses. All are plant-based, making them suitable for vegans and for those with allergy to egg.
Egg replacements have long-term potential due to the growing gravitation towards plant-based foods perceived by many consumers as better for the body, as well as the planet.
Josh Tetrick, CEO of Hampton Creek LLC, has taken egg replacement using starches to much publicized—and, recently, linguistically controversial—heights. Hampton Creek uses plant-based egg replacers not only in its Just Mayo mayonnaise-type product, but also in chocolate chip cookies and its egg-free Just Scramble egg alternative.
Tetrick’s team analyzed molecular structures and functionality to determine that synergistic blends of starch and hydrocolloids worked more efficiently than the individual ingredients. For example, physically modified, non-GMO corn starch works synergistically with pea protein, xanthan gum and alginate to create the texture and mouthfeel of traditional mayonnaise, while sorghum flour is used to replicate the characteristics of eggs in traditional cookies.
Hampton Creek’s Just Scramble is a scrambled egg alternative made from plant proteins. It caters to current clean label by containing no artificial ingredients, and it only uses familiar ingredients, such as corn starch. This is in line with as many as 53% of US consumers who worry about potentially harmful ingredients in the foods they buy, and 59% who think the fewer ingredients a product has, the more healthful it is, according to Lu Ann Williams, Director of Innovation, Innova Market Insights, in a report titled “Free-from Food Trends – US,” May 2015.
Snack makers can, by simply introducing a variety of starches in a sequence of coatings, impart unusual texture layers, ranging from crunchy to crispy. Visually, such techniques also can create a cracked color effect, for visual appeal to roasted or fried beans and nuts. Each coating layer, because of its distinct starch composition, has its own unique properties that define the appearance, texture, eating quality and flavor of the finished product.
For example, an undercoating of cooked waxy maize starch, with a high amylopectin content, expands rapidly during heating, while the second-coating layer, made with less amylopectin, unable to keep up with the expansion, separates to create the veined or cracked look. A unique property of waxy starches is a tackiness that allows for greater adherence to the underlying material.
Applications, such as coated nuts with a normally smooth or even oily surface, can accept a solid coating that stays intact during production and subsequent handling. This also has a production cost benefit, in that it translates to lower waste of the coating mix during transport and packaging.
Adding different colors to the two coating layers can bring another dimension of variation in the appearance of the snack. Simple formulation changes can create a variety of color and texture possibilities without the need for expensive production changes.
Size and Place
Visual, textural and performance possibilities increase multifold with the employment of different starch sizes. Sizes can be based on larger or smaller individual starch granules or on the overall molecular structure of the starch.
Particle size matters in starches. Starch granules come in a wide range of diameters, from as small as 3 microns to larger than 100 microns. Some starches show polymodal granule size; i.e., the granules can be grouped into several size ranges. Wheat starch has bimodal distribution with large and small granules. When separated by size, the coarse and large granulation works better to avoid dusting, while the smaller granules are used to blend in and provide a creamier texture without the addition of fat.
Granule shapes also are diverse, ranging from symmetrical spheres, asymmetrical (or lopsided) spheres, symmetrical disks and asymmetrical disks. Some starch granules exhibit their shape smoothly, while others are polyhedrons with a faceted surface.
Starches are valuable in coatings and batters, not just for their taste and textural contributions, but also for their interactions with water, oil and other ingredients. Nathan Myhrvold, co-author of the series “Modernist Cuisine” (Cooking Lab LLC, 2011), used sous vide cooking of potatoes to attain a tender consistency in the common tuber, then ultrasonic cavitation to create thousands of fissures that released starch granules over the surface of the potato. This technique led to a crispy surface of deep-fried potatoes.
There is a reason why chefs and processors coat French fried potatoes with physically modified potato and/or rice starches before frying. This gives fries an extended crispiness time, especially under a heating lamp.
Coated chicken products, such as chicken breast and chicken nuggets, rely on the starch in the batter coating to retain the moisture and keep the chicken juicier than it would be without the coating.
With the right starches in the coating mixture, it’s possible to reduce the amount of oil deep-fried products absorb. Native potato starch serves well as a binder in coatings because of its excellent expansion properties, and it provides a bonus of a high level of crunchiness.
The consumer desire for ingredients and finished foods to be as naturally healthy as possible encourages industrial manufacturers to seek naturally available starches as replacements for fabricated and processed counterparts in these battered, coated and fried foods.
While maltodextrins and pregelatinized starches long have been used as plating agents or as flavor encapsulation agents, native functional starches also are gaining ground as carriers of liquid flavors in foods, according to Milda Embuscado, PhD, CFS, and editor of “Functionalizing Carbohydrates for Food Applications” (DEStech Publications, 2014).
The stability of flavor in the final product depends on the absorptive capacity, particle size and bulk density of the starch used, as well as on the type of flavor to be plated. Starches with finer fissures possess a higher absorptive capacity and will afford greater depth of flavor against the backdrop of inert materials like maltodextrins that do not offer much protection or depth. This is because the flavor components only remain on the surface of the maltodextrin particles, which lack the fissures of starch granules.
Chemically modified starches commonly used for flavor encapsulation are increasingly based on waxy corn. In waxy corn, a hydrophobic substituent (often octenyl succinic anhydride [OSAn]) is added to the starch molecule to render it amphiphilic. This means the starch can now interact with both hydrophobic and hydrophilic components in a food system. This helps with flavors that typically are hydrophobic and must perform in food systems that are hydrophilic in nature, but without the flavor to separate from the aqueous system.
“Physically modified starches are the next frontier for encapsulating flavors that will remain homogenously dispersed without losing potency,” declares Embuscado. “All flavor-encapsulating starches are modified, but the food industry is [likely] developing one that can be classified as ‘natural’ [even though] it is not out in the market yet.”
Dry ingredients are more manageable and efficient than liquids, in general, especially when dealing with ingredients such as flavors and oils that are used in careful amounts for cost and effect. Milled, pregelatinized native corn starches can act as a clean label, high-loading carrier to overcome the inefficiencies of traditional, lower-load bearing synthetic carriers. This also helps mitigate the expense and complexity of techniques such as spray-drying.
Starches convert flavoring liquids and oils into free-flowing, non-sticky, dry powders for convenience across a broad range of applications. The possibilities multiply with clean label ingredients derived from identity-preserved non-GMO sources. These can be declared as simply “starch” of “flour” with or without revealing the source of the starch.
One unusual example is Amira Nature Foods Ltd.’s Amira Smoked Basmati Rice, a new product in the marketplace. It takes advantage of the fissures in rice starch trapping the flavor compounds, such that even after soaking and rinsing with water, the cooked product has a potent smoked flavor for a new twist on an ancient food.
It is estimated that, by 2020, more than 1 billion new people will place demands on food companies, causing processors to revisit their new product plans, according to the Organization for Economic Cooperation and Development Center. While many will design products customized to meet the needs of their existing consumer base, the savvy and the compassionate will create “low price point” products for scale and social responsibility. Starches, especially from new and untapped sources, are poised for this tall order, able to fulfill these demands without making taste and nutrition the privilege of only a few.
Starch in the Game
Another reason for the addition of waxy maize to drinks, especially sports beverages, is the in vitro starch availability of amylopectin-rich native starches. The availability of carbohydrates becomes a limiting factor for endurance athletes. These are athletes who perform high-intensity, intermittent activities, such as soccer, that often exceed 90 minutes. The slow-digesting starch in waxy maize leads to blunted plasma glucose and insulin response while sustaining an elevated blood glucose concentration over an extended period of time making it particularly useful in sports performance beverages for endurance athletes. For more on developing and manufacturing foods and beverage for sports and endurance, check out “The New Energy,” PF, October 2015.