A meat analogue, also called a meat alternative, meat substitute, mock meat, faux meat, imitation
meat, vegetarian meat, or vegan meat, approximates certain aesthetic qualities (e.g. texture,
flavor, appearance) and/or chemical characteristics of specific types of meat.
Generally, meat analogue means a food made from vegetarian ingredients, and sometimes
without animal products such as dairy.
Many analogues are soy-based (e.g. tofu, tempeh) or gluten-based, but now may also be pea protein-based.
The market for meat analogues includes vegetarians, vegans, non-vegetarians seeking to reduce
their meat consumption, and people following religious dietary laws in Hinduism, Judaism,
Islam, and Buddhism.
Tofu, a popular meat analogue made from soybeans, was invented in China during the Han dynasty.
A document written by Tao Gu (903–970) describes how tofu was called "small mutton" and valued
as an imitation meat.
Meat analogues such as tofu and wheat gluten are associated with Buddhist cuisine in China
and other parts of East Asia.
In Medieval Europe, meat analogues were popular during the Christian observance of Lent, when
the consumption of meat from warm-blooded animals is forbidden.
Meat analogue may also refer to a meat-based and/or less-expensive alternative to a particular
meat product, such as surimi.
An alternative modern technology is cultured meat grown in vitro from the muscle tissue
of animals.
== History == Tofu, a popular meat analogue, was invented
in China by the Han dynasty (206 BC–220 AD).
Drawings of tofu production have been discovered in a Han dynasty tomb.
Its use as a meat analogue is recorded in a document written by Tao Gu (simplified Chinese:
陶谷; traditional Chinese: 陶穀; pinyin: Táo Gǔ, 903–970).
Tao describes how tofu was popularly known as "small mutton" (Chinese: 小宰羊; pinyin:
xiǎo zǎiyáng), which shows that the Chinese valued tofu as an imitation meat.
Tofu was widely consumed during the Tang dynasty (618–907), and likely spread to Japan during
the later Tang or early Song dynasty.Prior to the arrival of Buddhism, China was predominantly
a meat consuming culture.
The vegetarian dietary laws of Buddhism led to development of meat analogues as a replacement
for the meat-based dishes that the Chinese were no longer able to consume as Buddhists.
Meat analogues such as tofu and wheat gluten are still associated with Buddhist cuisine
in China and other parts of East Asia.
Meat analogues were also popular in Medieval Europe during Lent, which prohibited the consumption
of warm-blooded animals, eggs, and dairy products.
Chopped almonds and grapes were used as a substitute for mincemeat.
Diced bread was made into imitation cracklings and greaves.The American medical physician,
inventor and businessman John Harvey Kellogg developed meat replacements variously from
nuts, grains, and soy, starting around 1877, to feed patients in his vegetarian sanitarium.
== Animal protein analogues ==
Some vegetarian meat analogues are based on centuries-old recipes for seitan (wheat gluten),
rice, mushrooms, legumes, tempeh, yam flour or pressed-tofu, with flavoring added to make
the finished product taste like chicken, beef, lamb, ham, sausage, seafood, etc.
Other alternatives use modified defatted peanut flour, Yuba and textured vegetable protein
(TVP); yuba and TVP are both soy-based meat analogues, the former made by layering the
thin skin which forms on top of boiled soy milk, and the latter being a dry bulk commodity
derived from soy and soy protein concentrate.
Some meat analogues include mycoprotein, such as Quorn which usually uses egg white as a
binder.
In April 2013, Beyond Meat began selling Beyond Chicken in Whole Foods stores in the US.
A mixture of soy and pea proteins, fiber, and other ingredients, the well-received product
was marketed as a healthy alternative to chicken meat.
The California-based company developed a number of other imitation meat products including
three different products to mimic beef and one to mimic pork sausage.
In 2016, Impossible Foods introduced a beef substitute, which it claimed offered appearance,
taste and cooking properties very similar to meat.
It uses a synthetic heme compound that is produced by genetically modified yeasts.
To replicate fat, flecks of coconut oil are mixed into ground textured wheat and potato
protein.Dairy analogues may be composed of processed rice, soy (tofu, soymilk, soy protein
isolate), almond, cashew, gluten (such as with the first non-dairy creamers), nutritional
yeast, or a combination of these, as well as flavoring to make it taste like milk, cheeses,
yogurt, mayonnaise, ice cream, cream cheese, sour cream, whipped cream, buttermilk, rarebit
or butter.
Many dairy analogues contain casein, which is extracted dried milk proteins, making them
unsuitable for vegans.
Egg substitutes include tofu, tapioca starch, ground flax seed, aquafaba, mashed bananas,
applesauce and commercially prepared products that recreate the leavening, binding and/or
textural effects of eggs in baked goods.
== Composition == Soy protein isolates or soybean flour and
gluten are usually used as foundation for most meat analogs that are available on the
market.
Soy protein isolate is a highly pure form of soy protein with a minimum protein content
of 90%.
The process of extracting the protein from the soybeans starts with the dehulling, or
decortication, of the seeds.
The seeds are then treated with solvents such as hexane in order extract the oil from them.
The oil-free soybean meal is then suspended in water and treated with alkali to dissolve
the protein while leaving behind the carbohydrates.
The alkaline solution is then treated with acidic substances in order to precipitate
the protein, before being washed and dried.
The removal of fats and carbohydrates, results in a product that has a relatively neutral
flavor.
Soy protein is also considered a “complete protein” as it contains all of the essential
amino acids that are crucial for proper human growth and development.Lipids are added to
the meat analog in the form of liquid or semi-liquid glyceride shortening from synthesis, or other
sources such as plants or animals.
The glycerides could potentially contain unsaturated or saturated long chain acyl radicals ranging
from 12 to around 22 carbon atoms.
Due to the target audience of meat analogs, plant based lipid sources such as soybean
oil, olive oil, canola oil, and others alike are usually used.
While lipids do not contribute to the structure of the meat analog, it is crucial in increasing
the palatability and broadening the appeal of the product across the consumer base.
Food additives include flavor compounds, coloring agents, leavening agents, and emulsifiers.
Sodium bicarbonate is a commonly used leavening agent in a variety of baked products such
as bread and pancakes.
The carbon dioxide released by sodium bicarbonate aids in the expansion and the unilateral stretching
of the protein network during production.
A variety of emulsifiers can be used to stabilize the meat analog system.
These could include, but are not limited to polyglycerol monoesters of fatty acids, monoacylglycerol
esters of dicarboxylic acids, sucrose monoesters of fatty acids, and phospholipids.
Polyglycerol monoesters consist on average of 2 to 10 glycerol units and an average of
one acyl fatty acid group per glycerol component.
The polymer is created from esterification reactions with fatty acids and contains 14
to 16 carbons per polyglycerol moiety.
Sucrose monoesters are derived from the esterification of sucrose with a fatty acid ester or a fatty
acid and it ideally should have a fatty acyl group ranging from 14 to 18 carbon atoms.
Lastly, phospholipid such as lecithin, cephalin, and sphingomyelin can also be used as effective
emulsifiers.
In addition, some of the emulsifier act as a lubricant during the extrusion process.
Overall the composition of dry protein mix can contain between 30% to 100% water-hydratable,
heat-coagulable protein by weight.
A dry mix that contains 100% protein content yields the most desirable fibrous texture,
but from the palatability standpoint between 50% to 70% was determined to generate the
most positive feedback.
Protein content of lower than 30% would inhibit the formation of meat-like fibers during processing.
The optimal fat content for the desirable mouth feel was determined to be around 30%
to 40% by weight.
== Processing == Meat analog products are currently made by
two basic processes, through either thermoplastic extrusion or fiber spinning.
Thermoplastic extrusion involves the adaptation of production processes that are more commonly
associated with the making of ready-to-eat cereal products.
Extruders are simple in nature and are considered to be a cost effective method of accommodating
large-scale productions.
It also provides the conditions that are crucial to the formation of the desirable fibers.
The wet mix is mixed in a heated vessel at a temperature lower than the coagulation temperature
of the proteins.
The elevated temperature assists in lowering the viscosity of the dough and allows for
a more homogenized mixing process.
Special caution must be taken as to not overmix the dough as it has been known to substantially
decrease the amount of fibers formed.Extruders should be set to the temperature in which
the protein used will start to coagulate for max efficiency.
Gluten and soy proteins coagulate at 75 °C and 68 °C respectively.
Due to the fact that the extruder also cooks the product, the temperature of the inner
walls of extruder should be within the range of 77 °C to 149 °C. Turbulent conditions
caused by aggressive mixing and agitation should be avoided during processing as it
contributes to the undesirable formation of randomly oriented, non-meat like fibers.
Unidirectional and parallel fibers can only be formed through extruding and stretching
under none turbulent, or laminar, conditions.
Laminar flow condition occurs under low velocities where the fluid in question flows smoothly
with overlapping layers, and it is characterized by having a Reynold number of less than 2040.
Stretching of the meat analog would take place simultaneously during the extrusion.
Ideally, the amount of linear expansion of the protein dough should be around 50% in
either direction.Fiber spinning method is not commonly used to produce meat analogs
due to its complexity, and it also negates one of the key advantages of meat analogs.
This method of production increases the cost of production, which eliminates the advantage
of creating an inexpensive meat/protein substitute.
The fiber spinning techniques were adopted from the spun fiber method used to create
synthetic fibers in the textile industry.
In general, fibers are made through creating filaments out of the protein used as the starting
material.
The process begins through the dispersion of proteins into a dispersing medium such
as an alkaline aqueous solution.
This dispersion is then fed through a spinneret, a device used to extrude a polymer solution
to form fibers, and deposited into an acidic salt solution with a pH range of 5.6 to 6.4
for coagulation.
The filaments after exiting the small die of the spinneret would have a diameter of
around .003 inches.
These filaments are then stretched and elongated until the average thickness is around 20 microns.Excess
salt solution is then removed from the fibers through squeezing or centrifuging prior to
further processing.
After the drying process, edible binders such as proteins, starches, cereals, dextrins,
carboxy methyl cellulose, or a combination of them, are added to keep the fibers physically
tied together through functioning as an adhesive or serving as a matrix in which the fibers
embed upon.
The fibers are then passed through a bath of melted fat and proceed to be pressed together
to form the final product.
The meat analog is then cut into suitable length for either packaging and distribution
or further processing.
Overall this method allows for the desirable formation of highly fine fibers, but at the
cost of longer and more complicated processing steps, as well as incurring an increase in
cost.
Regardless of which method was used, the final product should be stored under at temperatures
ranging from 13 °C to 21 °C. Ideally the humidity should be around 15%.
The expected shelf life of meat analog products while in an air tight package is up to 10
years, while it is only up to 1 year when it has been opened.
== Physical structure == The formation of fibers through protein coagulation
can be described through the wool and fiber models.
“Silk” fibers are characterized by its relatively high content of alanine, glycine,
and serine; these make up over 80% of the protein residue.
In order to give sufficient cohesion to resist flow, these protein chains form a tight fit
over a large area.
The proximity of the chains allows for firm hydrogen bonding to occur along the peptide
bonds of the chain backbone.
Although hydrogen bonds are relatively weak non-covalent interaction, the sheer quantity
of them increases their overall effectiveness in maintaining the structure.The “wool”
model is the more important model of the two as the composition of natural protein resembles
wool rather than silk.
This type of fiber is stabilized through cross-linkages as it provides strength and prevents plastic
flow resulting from slippage of protein chains.
Wool is much less crystalline due to its greater bulkiness of its side chains.
About 50% of the weight is composed of side chains.
Due to the abundance of hydrophobic groups, wet wool fibers are considerably stronger
than other synthetically made protein fibers.
This is the result of stabilizing through disulfide linkages.
When these bonds are broken at elevated temperature through hydrolysis or reduction, the wet wool
fibers lose its unique strength and act like typical synthetic protein fibers.The folding
and the unfolding of the proteins also contribute to the physical and mechanical properties
of the fibers formed.
Studies have shown that reversible “sol-gel” transformations take place within the amorphous
areas of the fibers.
Sol-gel refers to the production of solid materials from small molecules.
In material science, the process involves the transformation of monomers into a colloidal
solution (sol) that acts as the precursor to an integrated matrix (gel).
When the stabilizing bond between the fibers are broken, the system responds by unfolding
or slipping in attempt to relieve the tension.
The bonds would then rearrange in a less stressed position.
The uncoiling of the fibers, and to a less extent the stretching of bonds, contributes
to the elastic properties of the fiber.
While the plastic properties, or flow, are due to the slipping of protein chains pass
one another.
The behavior of the fibers can be shown by mechanical models consisting of combinations
of springs and dashpots connected in various combinations as demonstrated in figure 2.
The deformation of fibers can either be reversible, in the form of elastic properties, or irreversible,
in the form of plastic properties.
The elastic properties are represented by Hooke’s law constant (g1 and g2), while
the plastic properties are presented by a dashpot characterized by viscosity (μ).
The system in which the spring is in conjunction with the dashpot on the right side of figure
is known as the Maxwell viscoelastic unit.
The deformation can then be described by the spring system in conjunction with the Maxwell
unit.
An applied force, f1, on this model would be the sum of the partial forces f1 on the
spring at the left and f2 on the Maxwell unit.
The resulting strain on the system is dependent on the spring constants and the viscosity
of the dashpot.
The general assumption is that the dashpot behavior is Newtonian, in which the flow of
the viscous elements is directly proportional to the applied stress on the element.
This model only provides a simplified behavior of fibers, but in most cases, especially the
protein fibers, the characteristics are much more complex.
The matrix formed by the protein network is also affected by temperature.
Temperature has a large impact on the elastic properties of the fibers.
The interaction is similar to the influence of temperature on a gas.
The elastic tension of the stretched fibers is dependent upon the entropy of the system
in a manner analogous to the pressure of a confined gas.
When the temperature of the fiber is increased the thermal motion, like the pressure of a
heated gas is increased.
Equilibrium force acting on the rubber-like fiber is determined by thermal kinetic motions
of free chain segments between network junctions.
The thermal motions of the free chain segments promote random coiling at the junctions, thus
maximizing entropy.
A larger force is then required to displace the chains from the position similar to the
pressure required to compress a gas.
The elasticity of the fiber is increased as a direct result.
The emulsion in this instance is a water-in-oil one.
Studies have shown that by surrounding the water-soluble flavor extracts with the continuous
oil phase of the emulsion resulted in a slower rate of flavor dispersion from the water,
leading to the prolonged taste of flavor in the final product.
The oil phase effectively prevents the flavor-containing water particles from leaching out from the
product and transferring to the surrounding environment, such as sauces or other food
materials.
== See also ==
List of bacon substitutes List of meat substitutes
List of vegetarian and vegan companies Nut roast, an alternative to a Sunday roast
Nuteena, former (until 2005) vegetarian meat analogue made primarily from peanut meal,
soy, corn, and rice flour Single-cell protein, meat analogues containing
protein extract from pure or mixed cultures of algae, yeasts, fungi or bacteria
Tofurkey, faux turkey, a meat substitute in the form of a loaf or casserole of vegetarian
protein, usually made from tofu (soybean protein) or seitan (wheat protein) with a stuffing
made from grains or bread, flavored with a broth and seasoned with herbs and spices
== Notes ==
== External links ==
Research Market: vegetarian profits Soyfoods Association of North America
Meat-analogues on "FutureFood – Meat without livestock"