Texturization of Plant Proteins--The New Frontier
Walk into the freezer or refrigerated section of any grocery store, and you will find products with whimsically descriptive names such as Tofurky[r], Wham[r], Leanies[r], Gimme Lean[r], Tofu Pups[r], Fakin'Bacon[r] and Foney Boloney[r]. Although vegetarians were the initial target for these products, many other consumers are joining the craze for meat alternatives for various reasons.
These products offer entree alternatives for consumers reducing meat in their diets for health reasons, such as concern about developing heart disease, cancer or high blood pressure. From a health perspective, most meat alternatives are cholesterol-free, contain higher amounts of fiber and usually contain less fat than their animal product counterparts.
From a global perspective, many people do not have access to meat for economic reasons, lack of safe distribution, or limited supply due to cultural or agricultural limitations. Headlines about food safety concerns--E.Coli and listeria, BSE and other food safety issues--have changed meat-eating habits and sent people to look for alternatives.
In their online report, Mintel Consumer Intelligence divided the market for non-meat proteins or plant-derived proteins into three basic product categories: meat extenders, meat alternatives and meat analogs.
Each product has its particular challenges in marketing, product/process development, ingredient sourcing and production.
Revolutionary Ingredients Drive Product InnovationsThe increasing demand for all types of non-meat, high-protein products has resulted in new and highly profitable ventures for food manufacturers. Proteins derived from plant sources are becoming one of the food industry's fastest-growing and most-innovative ingredient segments. Plant proteins have increased functionality, a bland flavor profile, additional nutritional benefits, and a low-cost advantage as both meat extenders and meat alternatives. Advances in ingredient technology have enabled development of new ingredients to enhance many types of foods through improved emulsification, water binding, texture modification and flavor enhancement--all at an economical price.
The physical properties of foods such as meat, poultry, seafood, eggs and dairy products are defined mostly by their protein composition. The functional properties of some plant-derived proteins have the ability to mimic or parallel the physical properties of products like meat under certain conditions and treatments. Through technological advances, many plant protein characteristics have been altered to extend or even imitate meat products.
These modifications have been achieved through the use of enzymes, solvents, heat, fractionation, pH adjustment, or combinations of these treatments. One such treatment, the texturization of proteins through extrusion cooking, has revolutionized the food industry with the development of meat extenders and meat alternatives/substitutes.
Production-scale texturization of plant proteins into meat extenders and meat alternatives has been economically and technically feasible since the 1950s, but was first limited to a narrow range of raw materials, primarily soy and wheat proteins. Historically, wheat protein has been used for thousands of years as a meat substitute called seitan (say-THAN) in China, Japan, Korea, Russia and the Middle East. The soy industry became the leader in the ingredient market for meat alternatives in the 1940s, after textured soy protein first became a means of adding value to the soybean meal that was a by-product of the soy oil extraction process.
Manufacturers have pushed technology to increase protein content, improve functionality and improve overall flavor of soy products. Newer players have developed lines of certified non-GMO and organic ingredients for an ever-expanding market.
Wheat gluten, as well, is becoming a very large player in the industry, with new production facilities for gluten and texturized wheat protein products expanding all over the world.
Although there are several methods for processing plant proteins into texturized products, the use of twin-screw extrusion cooking has proven to be instrumental in the development of many new industry opportunities. A more involved processing method was first developed that re-dissolves precipitated proteins and passes them through a spinneret into a precipitating bath. The resulting fibrous material is then further processed through compacting, shaping and cooking. This process requires an expensive starting material, isolated protein, and costly initial capital investment (as well as costly running expenses).
In comparison, the extrusion process to texturize proteins provides continuous cooking of pre-moistened or conditioned materials, forming a plasticized mass through the combination of heat, pressure and mechanical shear. In addition to re-texturizing the plant proteins, the extrusion process provides other important functions, such as lowering protein solubility, increasing digestibility, deactivating heat-sensitive growth inhibitors, partial drying and generally reducing the microbial load.
Beyond Soy and WheatOver the years, research has been conducted on many other types of vegetable proteins and non-meat proteins such as casein, whey, albumin, etc., for use in meat analogs. In many cases, the limiting factor in using the ingredients is the functionality of the ingredients themselves.
While soy and wheat proteins are the ones most commonly texturized via the extrusion process, other proteins also can be texturized, according to Brad Strahm, senior product engineer at Wenger Manufacturing Inc. (Sabetha, Kan.).
“Pea, bean, sesame, peanut and cottonseed are some of the alternative proteins that we've worked with. The difficulty typically encountered with texturizing these proteins is that they are often not available in forms with sufficient protein content. Regardless of the protein source, a form with protein content greater than about 50% is typically needed to generate a product with a firm, meat-like texture,” he says. “Materials with lower protein content can sometimes be texturized, but the texture obtained will be very soft and weak.”
At its technical center in Sabetha, Kan., Wenger Manufacturing Inc. has performed many trials to determine the feasibility of some of the more novel ingredients.
Other limiting factors for texturizing proteins are fiber and fat/oil content of ingredients. Formulations with higher levels of fiber often require more shearing action (i.e., more energy) to achieve acceptable final products.
Speaking from experience, Steve Weier, extrusion process engineer in charge of the Extrusion Pilot Plant at the University of Nebraska Food Processing Center (Lincoln, Neb.), offers this recommendation: “In general, ingredient mixes containing oils, even at levels as low as 3%, will begin to interfere with the texturization process during extrusion.
“By adding mechanical and thermal energy to the process, one can still make an acceptable product with oil levels even up to 6% or 7%. As oil levels go beyond that range, the texturization becomes more and more difficult, and the quality of the product diminishes quickly.”
Higher levels of either fiber or fat, and even carbohydrates such as starch, can block the interactions or cross-linking of protein molecules necessary for good textural properties that simulate meat products. Formulations often require additional processing aids to increase the range of ingredients that can be used in meat analogs and meat alternatives.
Energizing the Meat Extender Ingredient MarketIngredients used for meat extension have included gums, starches and different protein sources. The industry has continued to develop and modify these ingredients to expand the yield and quality of the finished products. Pre-hydrated and pre-gelatinized ingredients have improved processing, resulting in increased yields and reduced processing times.
Increasingly popular in meat systems, both soy and wheat proteins offer functional benefits in products such as comminuted/emulsified and coarsely ground meats. Vegetable protein products (typical usage levels of 1%-4%) offer functional benefits of increased moisture retention and fat binding, as well as improved fat emulsifying properties. Another benefit is the overall appearance and yield enhancement of finished products, such as patties, sausages, loaves, meatballs, hot dogs and luncheon meats.
Flaked or crumbled forms of meat extenders, specifically texturized proteins, often are used in prepared products such as spaghetti sauce, chili or soups.
Many individuals, particularly those in the U.S., were first exposed to these extended meat products through the school lunch program. Starting in 1983, the USDA Food and Nutrition Service permitted the use of all forms of vegetable protein products as partial replacement for meat, poultry and seafood products in the school lunch and military foods programs. More recently, in April 2000, the regulations for vegetable protein products (VPP) were modified to allow alternative protein products (APP), removing the requirement that alternative products only be of vegetable plant origin. Limitations on the amount of vegetable protein products also were modified, no longer limiting the VPP to 30% or less (by weight) of the meat or meat-alternative component of the menu.
Canned meats have incorporated vegetable protein ingredients in retorted products to aid in the control of free juices and fats during the heating and cooling of the canning process, helping to avoid those fat or jelly-like globs from forming on the surface.
Seafood-based products often use vegetable protein ingredients to extend high-priced seafood products such as crab and lobster. The water-absorption properties, bland flavor and white color of many vegetable protein ingredients allow them to be used in items like fish nuggets, crab cakes, salmon patties, and even in tuna salad.
To Market to Buy a Meat AnalogNot just for vegetarians anymore, the plant protein industry targets worldwide markets seeking safe and economical meat replacement products. Even the USDA endorses texturized vegetable protein use by purchasing textured soy protein products to combat malnutrition in countries throughout the word (through the Food for Progress Program). In April of 2004, the USDA purchased 800 metric tons of texturized soy protein for a government food assistance program, the World Initiative for Soy in Human Health (WISHH). The rapidly expanding meat alternative and analog industry does not show signs of slowing down. New ingredient and processing technologies, combined with a more receptive and educated market, should add up to true value-added products and global acceptance.
Alternative Meat MarketMeat extenders are used in formulations containing meat to add structure, bind water and flavors, increase cooking yields and reduce costs (example: meat topping on pizza).
Meat alternatives are developed to function like meat and provide the nutritional equivalent of meats in the diet, but are not designed to have the organoleptic properties of meat (example: veggie burgers, particularly formulations using large quantities of whole grains and vegetables).
Meat analogs are developed to look, taste and have the texture of specific meat products (example: Wham or imitation bacon bits).