There are two main types of soymilk drinks and general applications.
The first is as a "plain" dairy alternative to cow milk,
while the second is a range of flavored drinks. Each have somewhat
different challenges in their processing.
Dairy alternative soymilk must be very "bland"
tasting to avoid the beany flavor, which is objectionable to many
non-Asian consumers. It must also have similar functionality to
cow milk, in drinks and food preparation. Even mildly flavored drinks
such as vanilla, require a very bland soymilk base. This challenge
requires sophisticated processing and formulation to achieve the
neutral taste while maintaining a good mouth-feel. A high proportion
of dissolved soymilk solids is desirable. Otherwise, the product
may be like a suspension, with particles settling and causing mouthfeel
problems such as chalkiness. Vacuum deodorization is a must, as
part of the processing line.
In addition, numerous other technical considerations are involved
in achieving the best yield, taste, mouthfeel and functionality.
Fortification with additional minerals and vitamins is an important
option. It is generally not cost-effective to try to produce totally
plain soymilk drinks in smaller quantities.
Flavored soymilk drinks, particularly strong ones
such as chocolate or some fruit flavors, are less of a challenge
with the issue of the beany off flavor since they usually mask some
of this. However, the base soymilk must still be relatively bland
and highly functional. Vacuum deodorization may be optional depending
on the final product and the quality of the main soymilk base production.
This allows medium and smaller volume production with somewhat simpler
processing equipment, however the flavoring formulas and mixing
may be more complex.
Packaging of many types is used internationally.
The most common is the higher-volume, long-life aseptic/UHT packages
such as TetraPak. This is generally only cost-effective at higher
production volumes in the 1,000 to 2,000 liter / hour minimum. However
contract packing at an existing milk packaging facility may allow
lower volumes to be handled. Newer milk carton packing is also allowing
extended shelf life (refrigerated) for about two months. Bottles
can also be used for extended, even non-refrigerated shelf-life,
but not for as long as the aseptic UHT. Plastic bottles and pouches
/ bags are used also for various products.
Yogurt and its derivative foods and drinks are some
of the easiest products to understand and produce for people with
dairy food experience. The processing of soy yogurt is almost identical
to that of cow milk, but with some very important differences.
Formulation is required, primarily to add a simple
carbohydrate such as sugar, to compensate for the missing lactose
found in cow milk. The bacterial culture, which can be the same
types as for cow milk, as well as others, needs the additional carbohydrate
to feed and develop. Another ingredient may be required to reduce
the surface separation of water, which occurs somewhat more than
with cow milk.
Flavored yogurt and drinks are easily formulated
and processed for packing the same way that traditional yogurt products
are packed. The flavored products when properly produced, are almost
identical in taste to cow milk versions.
Inclubation time and temperature are also adjusted
compared to traditional yogurt. Soy yogurt can require 6-10 hours
or more of incubation at temperatures near 40 C.
This is also partly determined by the type of finished yogurt and
the desired tart or neutral taste.
It is important to note that the soymilk base for making soy yogurt
products, does not have to be absolutely bland tasting and that
vacuum deodorization may not be necessary. This allows a less complex
system and also one with a medium or lower production volume. Nevertheless,
a good quality soymilk base is a must.
The most well-known and common soya dairy food is tofu. In
Asia it has been consumed for maybe 2,000 years, with its beginnings
in China. During the last twenty years, it has become well-known
and respected in much of the world, and mainly the developed western
countries. Now it is also beginning to be known in many developing
countries. It is similar to existing cow milk cheese products such
as paneer in India and peynir in Turkey, and is processed almost
the same way. It therefore provides an excellent soy protein alternative
to many traditional foods.
Coagulation is performed almost immediately after
the hot soymilk base is extracted from the processing line. The
temperature at which the coagulant is introduced as well as the
type of coagulant and type of pressing, all affect the consistency
and firmness of the tofu. Calcium chloride is one good option for
coagulation, since it introduces calcium to fortify the product.
The type of coagulant can also affect the taste of the tofu. Other
known coagulants are magnesium chloride, nigari (sea salt), citric
acid and acetic acid (such as in common vinegar).
Pressing of the soymilk curds is done after the
liquid whey water is drained away. The pressing can be manual, mechanical
or hydraulic. After the pressing, the large blocks are cut and then
cooled in a cold water bath.
Formulation is also possible with tofu. The addition
of herbs and spices and other ingredients can make the product more
ready to eat and easier to prepare at home.
The addition of other ingredients, before coagulation, requires
careful testing since some ingredients will negatively affect the
coagulation or pressing. Silken tofu, which is very soft and pudding-like,
is made without removing the whey water or pressing.
Derivative foods such as patties, burgers, "cottage
cheese" or quark, mayonnaise and other tofu-based foods are
all highly viable but require careful formulation and processing.
Packaging for the basic tofu is generally in either
a plastic container including a water bath and plastic film-sealed
top, or in a vacuum-sealed plastic wrap. Some stores simply sell
it in bulk from a vessel with a cold water bath.
Soymilk processing for tofu, as with yogurt, can be fairly basic
and at almost any volume of production. Some of the beany off-flavor
is gone with the drained whey water, and usually tofu is mixed with
other spices and cooked cover any residual beany flavor. Therefore
no vacuum deodorization is required in the soymilk line.
Soya Ice Cream
Like the yogurt category, soy-based ice cream is easy to produce
for experienced dairy processors. When properly formulated and processed
both hard and soft ice creams made from soymilk can equal the taste
of most high-quality ice creams.
Ingredients will vary depending on the product,
but basically the same types are used as for traditional ice cream.
One major difference is the need for additional oil and emulsifiers
to offset the lack of saturated fat in soymilk. The mouth-feel associated
with most commercial ice cream is partly related to the fat content,
and so soymilk ice cream will benefit from the inclusion of a vegetable
oil. Different stabilizers may be chosen as well.
Equipment necessary for both hard and soft ice
cream is identical to the cow milk versions. The difference is primarily
in the ingredients and processing.
Soymilk processing for the best quality ice cream should include
vacuum deodorization when producing mild flavors such as vanilla.
With chocolate or other strong flavors, a less bland soymilk base
can be used.
A wide variety of puddings and desserts is possible with
soymilk as the base. Basically any similar product made from cow
milk, can be made with soymilk. The question of beany flavor and
its treatment is similar to the case of ice cream. The more bland
the base milk, the more subtle the possible flavors. Pudding can
also be made with tofu, particularly silken tofu, but it is not
clear that this is more cost effective than making it directly from
soymilk. A thicker concentration of soymilk would be required than
for beverages. Vegetable oil and emulsifier addition to enhance
mouth-feel, and other ingredients to alter consistency, are considerations
in this process.
Packaging can be inexpensive, and like traditional
refrigerated yogurt products. However, long life, non-refrigerated
packaging is also available for this category.
The quality of the soymilk base is critical to the quality
of the resultant spray-dried soymilk powder. Only very large volumes
of production are feasible for spray-drying. However, other important
technical considerations are also involved.
Evaporation / concentration of the soymilk prior to spray drying
must be less than the usual cow milk since soymilk viscosity would
otherwise be too much for the process.
Although the main part of the spray drying equipment for traditional
milk powder is used, some equipment modification is necessary to
be able to spray dry the soymilk.
Agglomeration or instantization is a further process which allows
the finished powdered milk to be quickly reconstituted and dissolved
The variety of potential new products is limited only by the imagination
of processors and the taste of consumers. In the west, new varieties
of dairy-like soyfoods are introduced regularly and supermarkets
are expanding their choices. Many traditional foods can be supplemented
with various soyfoods to produce new consumer products.
The the proven health benefits, and growing consumer awareness of
soya, support the production and marketing of many existing and
Okara is the fiber rich by-product of the soymilk
process. It is an ideal ingredient in baking and cooking, and value-added
food processing. It is essentially available at no extra cost to
the processor, and is otherwise a waste product or animal feed.
The principal challenge is in drying it, for storage or shipment,
which can be expensive from an energy consumption point. If it can
be used in its wet stage, and further processed and formulated into
packaged foods, it is truly an economic bonus to the processor and
good nutrition for the consumer.