Coating in the food industry is the application of a
layer of liquid and/or solids onto a product.
The operation essentially relies on mechanical
energy and physical principles.
It consists mostly in setting the product particles in
motion and simultaneously applying the coating
ingredient in a certain pattern to expose one to the
The snack food industry
includes everything from chips
to confections ,from salty to
Most of the success of snack
food industry is due to the
coating that are applied.
Adhesion is the tendency of certain dissimilar
substance to cling together.
For fried snacks ,seasonings are typically
powder, no tack agent is needed for adhesion.
The dry products are sprayed with oil, then the
seasonings are applied and adheres to the oil.
Other tack agents includes water ,sugar water and
hydrocolloids, for these solutions drying is
Exception-fried corn chips, they require secondary
Coating ingredients generally used are
The most common snack food seasoning is salt, but
even with other seasonings ,salt is added to accentuate
The snack food association recommends a salt level
of 1.75% plus or minus 0.25% for salted potato chips.
Cube , dendritic and grainer salt are used.
The most popular flavors for salty snacks are cheese,
BBQ,sour cream and onion.
Typical seasoning levels are 8-10%,depending on the
seasoning and snacks base.
The flavor base frequently combines cheese ,tomato,
onion and garlic.
Monosodium glutamate, yeast extracts, disodium
inosinate and disodium guanylate can be added to
accentuate savory , salty flavors.
Size , shape , taste ,adherence and flow ability
of powder seasoning decides the quality of the coating.
If the powder is cohesive or ambient humidity gets too
high , spices clump, and uniformity in application
Many flavor powders are highly hygroscopic and
agglomerate easily, thus anti-caking agent is important
to keep the powders free flowing.
Small powders are more cohesive, thus more anticaking agent required.
Larger powders are more unlikely distributed than small
Coating pans and
Liquid coating and
The seasoning are dispensed over the belt , one side of the
snack only get coated, unless there is a device to flip the
In some foods such as potato chips, the chips are layered
two or three layers deep, so that more seasonings lands on
the top layers.
One study found that adherence dropped from 60% on the
top layers to 30% on the middle layer and 10% on the
Thus, a conveyor belt system may not produce snacks
that are as evenly coated as other methods, but requires
much less space.
Even coating on both the sides.
Thumble drums are horizontal cylinders with one side
raised so that product flows from one end to the other.
Flights are provided.
Spray nozzles and dispensing tubes can be installed
inside the drum, so that the snack may be sprayed with oil in
one section , then coated with powder in other section.
Enrobers works by dipping, Pouring or spraying a liquid coating
onto a core material.
Over thickening of enrobing material is prevented or controlled
by air knives, this is followed by shaker to remove further excess
Pre-bottomer for cooling.
For smoother coating ,they are coated with hydrocolloidal
solution i.e., when dried it gives glossy and smoothie flavour
Powder coating is usually by three methods
Pneumatically conveyed by forced air and
Oil are aplied to the surface of the products,along
with other flavors substance can also be added
Usually 80% sugar solution are sprayed.
It is mainly meant for its adhesion ability.
Powder is suspended in the oil in the ratio of
The basic of electrostatic coating is that by charging the
seasoning powder as it is dispensed,it is attracted to the
product,which grounded through contact with the
It reduces the seasoning fall off ,eventual coating and
reduce the oil content by 20%.
Eg: Seasoning of corn and tortilla chips.
Give an attractive appearance.
Define product shape.
Increases the shelf life.
Prevent migration of core constituents &
Create texture or maintain structural integrity.
Hand book of food science ,Technology and
169 chapter coating snack foods
Deparment of food science and
technology,The Ohio State University.