December 31, 2006
Using soy to mimic meat has made great strides in the last few years. From imitation chicken to beef, and even fish and shrimp, Cheryl Borders discusses the art of the possible for the 'great bean'
The soybean contains approximately 38 per cent protein, the quality of which compares favourably to beef, egg whites and casein when evaluated using the Protein Digestibility Corrected Amino Acid Score (PDCAAS). The soybean provides an excellent source of vegetable protein as it provides all the essential amino acids necessary for human health.
Soy-protein products are divided into three general categories based on their protein content: soy flour and grits (50 per cent protein on a moisture-free basis, mfb); soy protein concentrates (70 per cent protein, mfb); and isolated soy proteins (90 per cent protein, mfb).
The first step in processing is to crack the bean to facilitate hull removal. The cracked soybean pieces are then rolled into flakes to make oil extraction easier. The defatted soy flakes can be ground into flour, sized into grits or texturised through extrusion. Removing carbohydrates from the defatted flakes is the first step in making concentrates and isolates.
Soy concentrates are available in textured and powdered forms, which are considered traditional or functional. Traditional alcohol-washed concentrates can be used for protein fortification or the base material for making textured soy-protein concentrates. Functional concentrates exhibit water-holding capacity and emulsification capabilities, and form a gel when heated. Isolated soy proteins are available in a wide range of functionalities that are determined by temperature, pH and homogenisation during processing.
A wide variety of soy products can be used in meat analogues. The appropriate choice is determined by what type of meat product is being mimicked. Table 1, below, lists common forms of meat analogues.
Soy proteins are critical
When simulating coarse ground meat, manufacturers will typically use a combination of textured and nontextured soy proteins. The textured proteins include textured soy flours, textured soy concentrates, and textured combinations of vegetable proteins (eg, soy and wheat), all of which are available in a variety of sizes and colours. These proteins are used to provide texture and mouthfeel, contribute to appearance and bind water. They also are used for protein fortification and nutrition and as a source of insoluble fibre. Nontextured proteins can be used in conjunction and can include soy-protein concentrates and isolated soy proteins. These proteins are used to help with fat and water retention, emulsification (thereby contributing to mouthfeel and texture), protein fortification, and nutrition. In analogues simulating emulsified meats, such as hot dogs/bologna, functional soy concentrates and isolated soy proteins are often used for the same reasons.
In addition to the various soy proteins, other protein sources can be found in meat analogues. Wheat protein, such as gluten, can be incorporated to help with binding and texture. Egg whites are another protein that can contribute to binding as well as 'bite' during the eating experience, but they are not suitable for vegan applications.
Nutrition, texture, flavour
When beginning the development of a meat analogue, the developer must take several things into consideration.
After selecting the meat counterpart that the developer wants to simulate, it is important to identify the desired nutritional content of the finished product. Setting targets for nutrients, such as fat or sodium, early in the development process can reduce time-consuming reformulation later. The intended consumer market can influence what ingredients are acceptable from a labelling standpoint.
Another important point to remember is that all the inherent attributes found in a meat product â texture, flavour, fat, colour â must be added to the analogue by the product developer. Developing acceptable texture and flavour can often prove to be the biggest challenges. Table 2, below, lists common ingredients found in meat analogues and typical usage levels.
To improve on binding and develop meat-like texture, other nonprotein ingredients can be incorporated. Carrageenan, cellulose gums and starches are often found in ingredient declarations. Their water-holding abilities and gelling characteristics will affect the texture and mouthfeel of the finished product. The order in which ingredients are added can be important in developing desired attributes in the analogue. If using an isolated soy protein or functional soy concentrate in a veggie hot-dog formulation, for example, it is important to develop the functional properties of the soy proteins. Typically, this is accomplished by hydrating the protein with a sufficient amount of cold water and applying mechanical action. If a fat source is used in the formulation, it is added to the hydrated protein with mechanical action to form an emulsion. This is followed by the remaining ingredients: binding agents, flavours and colours.
As mentioned earlier, other ingredients such as starches and hydrocolloids may also require certain procedures to develop their functionality. Some analogues may only require blending of the dry ingredients followed by the addition of water to prepare for forming or cooking.
As the meat-analogue category has grown, flavour houses have responded with a wide range of flavours for the application, while protein suppliers have been able to offer ingredients with cleaner flavour profiles. Flavour suppliers can provide the characteristic meaty note to the analogue as well as important background notes such as fatty, serumy, roasted, etc. The various proteins that are found in the base matrix may have an inherent cereal note, and flavour suppliers have developed masking agents to reduce these notes. In addition, proteins have a tendency to bind with certain components in the flavour ingredients and this can have a negative impact on the overall flavour profile. It is important for the developer to consult the flavour supplier for ingredients that will work in their base matrix and comply with any other requirements, such as kosher status or use of artificial flavours.
In the past few years, meat analogues that closely mimic the texture of whole muscle meat have been introduced into the marketplace. They are produced using high-moisture extrusion, a technology that has been available for about 25 years. These high-moisture analogues typically contain a combination of proteins such as soy, wheat and/or egg in conjunction with starches, vegetable oils, flavours and colours.
Containing a relatively high moisture level â 50-80 per cent â the blend is processed using twin-screw extrusion that yields a meat analogue with a tender, moist texture and meat-like fibres. (Traditional textured proteins are generally extruded at less than 35 per cent moisture and require prehydration prior to use.) The base products are mild tasting and can be easily flavoured prior to extrusion to resemble poultry and meat. The high-moisture content helps reduce the release of volatiles when the product exits the extruder.
Upon exiting the extruder, the analogue is sized and, if desired, the appearance can be enhanced with char-grilled marks or by searing for an oven-roasted look. Products are available in strips, shreds, dices and chunks, and can also be battered and breaded.
Meat analogues are more frequently finding their way into convenient frozen entrÃ©es. The products range from sandwiches to lasagna and frozen dinners. Reasons for purchasing analogues vary but consumers often mention religious beliefs, environmental concerns, animal rights and health benefits. In fact, according to a 2006 United Soybean Board survey, 82 per cent of consumers perceive soy products as healthy and 31 per cent select products containing soy for their health benefits.
In the future, food manufacturers will need to continue to be innovative and offer meat analogues with health and nutritional benefits, convenience and improved flavour and texture. The soy-protein ingredients have become more versatile with cleaner flavour profiles due to improvements in processing, and the challenge of using soy proteins has been minimised.
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