Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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definition given above, such as cake-, meringue-, and

pastry-based products. Biscuits that are too large to

be put in the mouth at one time, would be called les

petits ga

teaux secs, meaning small dry cakes. A simi-

lar distinction exists in Germany where biscuits are

called kekse or konfekt, but only if they are small.

0007 In the UK, biscuits are classified on their formula-

tion, the two major categories being hard and short

doughs. Hard doughs are similar to bread doughs but

have a much stiffer consistency. With hard doughs,

the three-dimensional gluten network is well de-

veloped during the mixing process, so the dough is

both elastic and extensible. The formula for hard

doughs is very lean, as the content of fat and sugar

relative to flour is very low. Crackers are made

from hard doughs, as are semisweet, unsweetened,

and savory biscuits. Short doughs are more closely

related to cake doughs than bread doughs, although

they have less water than a standard cake formula.

Short doughs are named for the higher content of

shortening or fat than hard doughs. They also have

a higher sugar content. The increased levels of fat

reduce dough extensibility, causing this type of biscuit

or cookie to break easily. The flour in short doughs

is given very little mixing, so the development of

a gluten network is minimized. The consistency of

short doughs has been compared with wet sand;

they hold together under pressure but crumble easily.

Short doughs have a subgroup called soft doughs that

have higher levels of fat and sugar, resulting in a

dough with an even softer consistency.

0008 Biscuit classification in the USA is based on the

method of processing and, in particular, the way the

biscuits are shaped. The four main categories are

sheeting or cutting (sometimes called cutting machine

doughs), rotary molding, wire cutting, and deposit-

ing. Sheeting is used for doughs that would be classi-

fied as hard doughs in the UK and is always used for

making crackers. The dough is passed through a

series of rollers until it reaches the required thickness.

The biscuit or cracker shapes are then cut out of the

dough sheets using a plastic or metal die. It is import-

ant that the dough is strong and elastic so that the

biscuits and cracker shapes do not deform when excess

scrap dough is removed from around the shapes.

Rotary molding is used for short doughs, and requires

a dough with a relatively stiff consistency that is

not too sticky. The dough is compressed into dies

mounted on the surface of a roller, and any excess

dough is scraped off. The molded dough piece retains

its shape as it is pushed out of the die on to the baking

sheet or band. Short doughs may also be shaped by

wire cutting, which involves extruding the dough

through a die and slicing it with a tight wire at

appropriate intervals. The tension placed on the

dough during extrusion and the thickness of the

wire will vary for different types of doughs. Because

soft doughs are similar to a batter, having a semifluid

consistency and lacking cohesiveness, they are shaped

by depositing. The dough is extruded through a

nozzle and dropped on to the baking sheet or band.

To achieve uniformity in size and shape of the biscuits

or cookies, the flow of dough is cut off at regular

intervals.

Features of Biscuits

0009To further explore the nature of biscuits, cookies, and

crackers, this section examines the main types of these

products in more detail. Products are categorized by

the hard and short dough classification with a discus-

sion of the distinct features necessary for the different

forming processes. The wide range of shapes, sizes,

textures, flavors, and colors of biscuits is illustrated in

Figure 1.

Crackers made from Hard Doughs

0010Crackers are characterized by very low fat and sugar

levels. They are often used as a base for a savory

topping, such as cheese or tomato, but the modern

snack cracker, with its tasty coatings and flavors, may

be eaten without additions. Crackers may be further

subdivided into those that are fermented, including

soda crackers, saltines, and cream crackers, and those

that are chemically leavened like the popular snack

cracker.

0011Soda crackers have been popular in the USA for

over 150 years. They are typically 4 mm thick and

50 50 mm square. The shortening content is 8–

10%. Saltines are a smaller, more dainty type of

soda cracker with an increased amount of shortening.

Traditional soda cracker manufacture involves a long

fermentation using a sponge starter. Soda crackers

have a significant amount of sodium bicarbonate

added to the dough (1%), which increases the alka-

linity and is the reason for the name of the cracker.

Once the dough is mature, it is sheeted to about 4 mm

and then laminated six to eight times. The cracker is

cut by making lines of perforations and baked as a

whole sheet, a process that minimizes the amount of

waste dough. A feature of soda crackers is the nine

hole docking pattern on each cracker, set out in a

3 3 grid pattern. After baking, the sheet of crackers

is split along the perforation lines, usually to make a

block of four crackers for packaging. The final prod-

uct is quite flaky but crisp. The spring between the

docking holes on the top of the cracker should be

even, and the bottom surface should be almost flat

with numerous small blisters. Because soda crackers

are quite dry and bland, they are not usually eaten

BISCUITS, COOKIES, AND CRACKERS/Nature of the Products 525

alone and are often used as an accompaniment to

soup.

0012 In the UK, soda crackers are rare, and cream

crackers fill a similar market niche. Despite their

name, cream crackers contain no cream! They have

a slightly higher fat content (12–18%) than soda

crackers. Cream crackers are generally a 65 75 mm

rectangular shape and are slightly thicker than soda

crackers with around 6.5 mm between biscuits

stacked in a column. Unlike soda crackers, they are

usually produced as individual units. While, trad-

itionally, the long sponge and dough fermentation

process was used for manufacturing cream crackers,

modern techniques involve a single-stage mixing and

fermentation process, which takes from 4 to 16 h. As

with soda crackers, cream crackers are sheeted and

laminated. A feature of cream crackers is the laminat-

ing ‘dust’, consisting of flour, shortening, and salt,

that is applied between the layers of dough. This

causes the laminations to lift apart during baking,

giving an extra flaky structure. The movement of

the laminations and subsequent surface blistering

are quite irregular, giving the cream cracker its char-

acteristic uneven surface. Blisters are present on both

the top and bottom surfaces. Cream crackers have a

final moisture content of 3–4%, which is quite high

for a cracker, and along with the increased fat con-

tent, the cracker is relatively soft, will not crumble

and should ‘melt in the mouth’. Without chemical

leavening, cream crackers are bland but have a

slightly nutty flavor. They are mostly eaten with a

savory topping and are often buttered.

0013Snack or savory crackers have a more recent his-

tory than soda and cream crackers. They have two

distinguishing characteristics. The first is that the

cracker is sprayed with hot oil as it leaves the oven,

and the second is that a topping is applied to the

crackers to add flavor. Snack crackers usually contain

some sugar (4–10%), which also adds flavor and

texture. They are usually chemically leavened, but

some snack crackers are made from fermented

doughs. Because snack crackers do not have the

long fermentation to mature the dough, proteolytic

enzymes or sulfites are used to relax the doughs so

that the crackers do not deform during sheeting and

cutting. Snack crackers come in a wide range of

shapes and sizes, but are often round and have

docking holes to allow an even lift during baking.

Only snack crackers produced by fermentation are

laminated. Toppings are generally applied before

baking, and include herb, cheese, salt, chicken, and

smoke flavors. Sometimes, the crackers are decorated

with small seeds, such as poppy, sesame, or celery.

Snack crackers have a dense texture and are quite

soft. The hot oil spray improves the mouth feel and

gives an attractive appearance to the finished product.

Sweet and Semisweet Biscuits made from Hard

Doughs

0014Sweet and semisweet biscuits made from hard dough

are generally more popular in the UK than the USA.

While the gluten network is relatively well developed

by mixing, the higher amounts of sugar (around 20%

of flour) and fat (16–20%) than in cracker doughs

fig0001 Figure 1 (see color plate 9) Biscuits come in a wide range of shapes, sizes, textures, flavors, and colors.

526 BISCUITS, COOKIES, AND CRACKERS/Nature of the Products

make the gluten less elastic and more extensible.

Chemicals, such as sodium metabisulfite or other

chemical derivatives of sulfur dioxide, can also be

used to condition and relax the dough to facilitate

processing. Unlike cracker doughs, most hard sweet

and semisweet biscuit doughs are chemically leavened.

After mixing, the dough is sheeted and formed into

shapes. The individual biscuits are cut out of the

dough sheet, leaving a web of scrap dough to be

removed and incorporated back into the main batch

of dough. These biscuits are generally docked and

marked with a name or pattern before baking. Some-

times, a milk or egg/milk wash is applied to enhance

their appearance after baking, and occasionally, a

garnish of sugar or other granular material is applied.

0015 Baked biscuits should have a smooth, even surface

with a pale color. The texture of the biscuit is open

and even, giving a delicate bite, although this is some-

what dependent on the formula – lower levels of sugar

result in a harder bite. The ingredients in sweet and

semisweet biscuits are quite plain, so the flavor is

usually a mild vanilla, caramel, or buttery flavor.

The biscuits are generally served without accompany-

ing food and are eaten with tea or coffee. There are

some interesting variations of sweet and semisweet

biscuits, such as those that are processed after baking

to incorporate a cream sandwich or chocolate

coating. The garibaldi fruit sandwich biscuits have

a layer of currant or small sultana filling between

two layers of hard dough.

Biscuits or Cookies made from Short Doughs

0016 The vast majority of biscuits and cookies consumed

world-wide are made from short doughs, and con-

sequently the range of shapes, sizes, flavors, and

ingredients is huge. Formulae are correspondingly

variable, but there are some consistent requirements.

Flour is usually weak, with less than 9.5% protein.

While there are no rules for the proportions of fat and

sugar, which can range up to 100 and 200% of flour

weight, respectively, the quality of these ingredients is

important since they make up such a large proportion

of the dough. Short doughs are usually mixed in a

two-stage process with an initial creaming of the fat

and sugar, although modern techniques tend to use

the ‘all-in’ mixing method. The doughs are cohesive

and plastic but lack extensibility and elasticity. The

consistency of the dough will vary according to the

requirements of the machinery used to form and

shape the biscuits.

0017 As described above, the two main processes for

forming short dough biscuits and cookies are rotary

molding and wire-cutting. Rotary molding originated

from the simple wooden molds often used in mon-

astery kitchens to produce biscuits and cookies

containing inscriptions. With a rotary mold, dough

is continually fed from a hopper and forced into a

metal die on a rotating roller. The formed dough

shape is pressed out of the mold on to the baking

band as the roller rotates. Unlike hard doughs,

which tend to shrink during baking, short and soft

doughs generally spread because of the high sugar

and fat content. This is a particular disadvantage of

rotary molding as the inscription can become blurred.

Tight control of the formula is necessary to reduce

spread. Rotary cookies should be thin and smooth

with no surface cracks or irregularities. Because of

their regular size and shape, rotary cookies may be

used to make cream sandwiches in the same way as

hard sweet biscuits.

0018Wire-cutting is a form of extrusion; the dough

passes through a die and is sliced at intervals by a

tight wire so that the formed dough shape drops on to

the baking band. Doughs intended for wire-cutting

are usually softer than rotary molding doughs, and

more chunky ingredients, such as chocolate chips,

nuts, or raisins, may be incorporated. A variation on

the wire-cutting process is a rout press that extrudes

dough continuously. The dies on a rout press are

designed to produce strips, which are cut into short

lengths before baking. Both of these techniques can be

adapted to coextrude by having two different doughs

or a dough and a filling coming from separate

hoppers into a single die that forms a dual layer

cookie (e.g., chocolate/vanilla) or a dough tube

often filled with a fruit paste of similar consistency.

Biscuits or Cookies made from Soft Doughs

0019Soft doughs have a pourable consistency, are typically

rich in fat (65–76% of flour weight), and may be

based on whipped egg whites (15–25%). Sugar is

around 35–40% of the flour weight. Weak flour is

used, and mixing is in a two-stage process. The flour

and other dry ingredients are added last, and only

minimal mixing takes place to prevent the dough

from becoming tough. Often, rich, expensive ingredi-

ents, such as ground almonds, coconut flour, or

cocoa, are used in soft doughs. However, coarse par-

ticles are avoided, because they may block the nozzles

during depositing. Dough temperatures are important

to achieve the correct consistency for forming the

specific type of biscuit or cookie required. Tempera-

tures generally range between 10 and 17



C. The

dough flows from the hopper through a nozzle on to

the baking band. The nozzles may be of different

shapes and sizes to alter the appearance of the cookie,

but because the dough flows a little after depositing,

these designs may be rather irregular. Some depositor

heads can be rotated to make swirls and circular

shapes, while two or more depositors may be

BISCUITS, COOKIES, AND CRACKERS/Nature of the Products 527

synchronized to combine doughs of different flavors

or colors within the same biscuit or cookie. Soft

dough biscuits and cookies have a soft, delicate tex-

ture and a ‘melt-in-the-mouth’ feel. However, these

properties make them fragile and subject to breakage,

and packaging can also be difficult because of the

irregular shapes.

Finishing and Decorating Biscuits

0020 While the basic biscuit, cookie, or cracker is distin-

guished by the processes described so far, the nature

of the final product can be significantly altered by

secondary processing after baking. A wide range of

processes are used to finish and decorate biscuits,

cookies, or crackers, some of which have already

been referred to. Two of the most popular are cream

sandwiches and chocolate coating or enrobing. In a

cream sandwich, the cream usually makes up about

30% of the final biscuit weight and consists of sugar,

fat, and flavorings, such as fruit acids, cocoa powder,

and skimmed milk powder. The cream is either

poured into a stencil positioned over the top of

the biscuit base or deposited directly on to the

base. Working with chocolate is technically difficult

because of the necessity to control the temperature

accurately. The properties of chocolate are quite vari-

able and depend on the ingredients that were used to

make the chocolate. Various methods of fully enrob-

ing or partially dipping the biscuit or cookie into a

chocolate bath are used, depending on product speci-

fications. Icings, made from icing sugar, water, and

sometimes fat or a gelling agent such as gelatine, are

another popular finishing on biscuits. Jellies, jams,

marshmallow, caramel, fruit, seeds, and nuts may

also be used to enhance the taste and texture of

biscuits, cookies or crackers.

See also: Biscuits, Cookies, and Crackers: Methods of

Manufacture; Chemistry of Biscuit Making; Wafers

Further Reading

Anon (1979) The Cookie and Cracker Manufacturing

Correspondence Course. Unit IV Crackers. Washington,

DC: The Biscuit and Cracker Manufacturers’ Associ-

ation.

Anon (1999a) Biscuit Production. Baking Distance Learn-

ing Course. Christchurch, New Zealand: New Zealand

Institute for Crop & Food Research.

Anon (1999b) The Science of Baking Correspondence

Course. Saltines/Snack Crackers. Manhattan, KS: The

American Institute of Baking.

France WJ and Small M (1986) The New International

Confectioner, 5th edn. London: Virtue & Company.

Kulp K (1994) Cookie Chemistry and Technology. Manhat-

tan, KS: The American Institute of Baking.

Manley D (2000) Technology of Biscuits, Crackers and

Cookies, 3rd edn. Cambridge, UK: Woodhead.

Matz SA (1992) Cookie and Cracker Technology, 3rd edn.

McAllen TX: Pan-Tech International.

Smith WH (1972) Biscuits, Crackers and Cookies, vols. 1

and 2. London: Applied Science.

Wade P (1988) The Principles of the Craft. Biscuits,

Cookies and Crackers, vol. 1. London: Elsevier.

Methods of Manufacture

L Doescher Miller, Formerly of The Pillsbury

Company, Minneapolis, MN, USA

This article is reproduced from Encyclopaedia of Food Science,

Background

0001The manufacturing process used to produce all bis-

cuits, cookies, and crackers consists of a mixing step,

a shaping or forming step, and a baking step. The

mixing and baking steps are common to the manufac-

ture of all types of these products. What is distinct for

the products are the shaping or forming steps. In this

article, the processes used to produce these products

will be described.

Mixing

0002Mixing is commonly defined as a process designed to

blend separate materials into a uniform, homoge-

neous mixture. In the context of cookie and cracker

doughs, the term takes on a broader meaning in that it

also applies to the development of gluten from hy-

drated flour proteins, the aeration of a mass to give a

lower density, and the dispersion of solids in liquids.

One or more of the functions is required for the

formation of cookie and cracker doughs. These pro-

cesses are accomplished with three principal types of

mixers: vertical spindle mixers, horizontal drum

mixers, and continuous mixers. (See Bread: Dough

Mixing and Testing Operations.)

Vertical Spindle Mixers

0003Vertical mixers were used extensively before the

development of the high-speed mixer. Although

usage has decreased overall, this type of mixer is still

used for crackers and semisweet doughs, for which

the vertical spindle design is particularly well suited.

The feature that all vertical mixers have in common is

the portable dough trough, which serves as the

mixing vessel. The trough is usually a wheel-mounted,

heavy tub with vertical sides, round ends, and a flat

bottom. The trough is designed so that it may be

528 BISCUITS, COOKIES, AND CRACKERS/Methods of Manufacture

wheeled into position below the mixer head and

locked into place. Mounted on an overhead frame

are the drive mechanism and spindles with horizontal

paddles or arms. Most mixers of this type are

equipped with two or three spindles. The spindles

are lowered into the trough and move in either a

planetary or a stationary, circular motion when acti-

vated. The shape of the arms forces the dough up-

wards and downwards in the trough, generating a

mixing action. The mixer blades are designed to pro-

vide a cutting action rather than kneading or stretch-

ing the dough.

0004 The advantage of vertical spindle mixers is that

they can be used for almost any product. They are

very well suited for products such as soda cracker

doughs. These doughs require a two-stage mixing

sequence separated by a fermentation period. The

sponges and doughs do not have to be transferred in

and out of the trough at each mixing stage. Instead,

they remain in the same trough for the entire mixing/

fermentation sequence. Because there is almost no

heat generated during the mixing process, this mixer

is ideal for doughs that must remain cool. The mixing

action is very gentle. Doughs containing ingredients

or particulates that are easily damaged may be safely

mixed with this mixer type.

0005 The primary disadvantage of vertical mixers is

their slow operating speed. The spindles rotate over

a limited range at two or three speeds, up to a max-

imum of approximately 20 rpm. For doughs requiring

the development of a gluten network, the mixing time

required may be as long as 90 min. Because this is

slow relative to the speed of the remainder of the

processing line, several mixers may be needed to

maintain an uninterrupted dough supply. Other dis-

advantages include lack of uniformity of the mix, and

the labor-intensive nature of the system’s design. The

latter disadvantage relates to the fact that the dough

troughs are very heavy, requiring special equipment

to move, lift, and tilt the tubs at each stage of the

process.

Horizontal Mixers

0006 The feature that all mixers of this type have in

common is a horizontal bowl mounted on a rigid

frame that encloses the drive motor. The bowl may

be stationary with a vertical front wall that slides

down so that the dough may be ejected. More com-

monly, the mixer bowl is designed to tilt, and the

dough is ejected from the tilted position. In both

designs, the top cover is fixed so that mixing takes

place in an enclosed space.

0007 The blades of horizontal mixers are mounted on a

horizontal shaft and may have any of several different

shapes, depending on whether a cutting, scraping, or

kneading action is needed. Mixing times for cookie

and cracker doughs range from 5 min for soft cookie

doughs to 30 min for the hard doughs, which require

gluten development. Most mixers of this type are

fitted with a jacket surrounding the mixing chamber.

This allows a coolant to be circulated, so that dough

temperatures can be controlled. Without such con-

trol, horizontal mixers can increase the dough tem-

peratures to the point where dough handling and

finished product properties are adversely affected.

0008The advantages of horizontal mixers are their high

speed, ability to supply dough to a processing line

continuously, uniformity of the mixes they produce,

and their potential for complete automation. Hori-

zontal mixers may be operated at speeds of 15–

80 rpm. Commonly, their power train is equipped

for two-speed rotation. Unlike most vertical spindle

mixers, ingredients may be added with the blades in

motion, and the discharge of the dough from the

mixer is simple. Accurate control of dough tempera-

ture is possible, because there is a continuously circu-

lating refrigerant.

0009Horizontal mixers require that all ingredient

charging spouts be located overhead or that ingredi-

ents be added manually. Charging the mixer with

ingredients is typically a significant portion of the

total mixing cycle time. During mixing, the blades

may throw material to the top of the chamber, so

that it is never fully incorporated. With the shaft

and mixing blades located in the center of the bowl,

dough discharge is not always rapid and may occur in

several large fragments. Only one operation (charging,

mixing or discharging) may be performed at any one

time, so that fast cycling of the dough batches may

not be possible.

0010Horizontal mixers usually have capacities of up to

550 kg. The weight and the vibrations generated by

their relatively high operating speeds place special

design demands on the production facility. In add-

ition to a reinforced floor, special mounts are neces-

sary to secure the mixer in place.

Continuous Mixers

0011Continuous mixers are best described as a rotor or

screw operating within a barrel jacketed for tempera-

ture control. The ingredients are fed continuously,

either from one end of the barrel or in successive

ports at intervals along its length. The mixing action

may be altered from gentle blending and dispersing to

vigorous or high-intensity kneading by varying the

arrangement of different mixing arms along the

length of the barrel. The amount of work put into

the dough during its transit may be controlled add-

itionally by restricting the dimension of the outlet

orifice, creating a back pressure inside the barrel.

BISCUITS, COOKIES, AND CRACKERS/Methods of Manufacture 529

0012 Continuous mixers are favored in some plants be-

cause they are capable of providing a constant supply

of dough to production line, all of uniform age. Con-

tinuous mixers are small in size relative to horizontal

mixers and are suitable for complete automation. In

spite of this advantage, continuous mixers are not

common in cookie or cracker plants, where a single

line may be required to produce a variety of products.

They are usually used only on high-output lines

having a single purpose or similar product types.

0013 The primary disadvantages of this mixer type are

its high cost and the additional cost of the associated

automated, continuous ingredient feeding systems.

Beyond this, continuous mix systems are not particu-

larly flexible; different products usually require com-

pletely different types of machines. In addition, the

initial process set-up can be difficult, requiring

considerable experimentation to determine optimum

mixing conditions and sequences. Finally, starting

and stopping the process are difficult in the event of

any problem along the rest of the production line.

The Forming Process

0014 While the same mixing and baking process may be

used for many types of cookies and crackers, the

forming step is specific to each product type. There

are three processes used to form cookie and cracker

doughs: (1) cutting or stamping from a continuous

sheet of dough, (2) rotary molding by shaping dough

in die cavities cut into the surface of a metal cylinder,

and (3) extruding dough through a shaped die.

0015 For each of these methods, the rheology of the

dough is different and is designed to be compatible

with the process. In general, doughs that are to be

sheeted possess a significant gluten network as a

result of mixing, and are both elastic and extensible.

Those destined for rotary molding lack gluten devel-

opment and are best described as cohesive. Doughs

intended for extrusion are soft, frequently high in

shortening, and spread while baking.

Sheeting and Cutting

0016The most common and versatile method to form

cookie and cracker doughs is sheeting and cutting.

This method involves the production of a thick sheet

of dough, evenly reducing the thickness of the sheet,

cutting out the desired shapes, and returning the scrap

dough to be reincorporated either in the mixer or

early in the sheeting process. This method is used

for the production of crackers, semisweet biscuits,

and selected soft doughs.

0017After mixing, the dough is fed into a hopper, below

which lie the sheeting rollers. There are typically three

rollers below the hopper arranged in a triangular

fashion (Figure 1). At least one of the top two rollers,

known as forcing rollers (labeled A in the figure), is

grooved so that a positive feed is provided to the

gauge or gauging roller. The gauging roller (B),

which is always smooth, serves to deliver the dough

to the conveyor belt (C). The purpose of the sheeting

unit is to compact the mass from dough hopper uni-

formly and provide a sheet of even thickness having

the width of the processing line.

0018The relatively thick dough slab from the sheeter

then passes through a series of reduction or gauge

rollers (D). These are smooth steel rollers used to

reduce the dough sheet to the thickness that is desired

before cutting of the finished dough piece. The gauge

rollers occur in pairs mounted vertically. For products

having sticky or adherent doughs, it may be necessary

to mount a scraper blade against one or both of the

rollers to release the sheet of dough. On most process

lines, there are two or three pairs of rollers. This

ensures that the thickness is reduced no more than

50% at any one rolling operation.

0019Some doughs, such as those of saltines and cream

crackers, are laminated before cutting. The lamin-

ation occurs by lapping the dough back upon itself

in the process direction. At the lapper, the take-away

conveyor lies at a 90



angle relative to the line deliver-

ing the dough. The number of layers is controlled by

fig0001 Figure 1 Sheeting and cutting process. See text for explanation. Reproduced from Biscuits, Cookies and Crackers: Methods

of Manufacture, Encyclopaedia of Food Science, Food Technology and Nutrition, Macrae R, Robinson RK and Sadler MJ (eds), 1993,

Academic Press.

530 BISCUITS, COOKIES, AND CRACKERS/Methods of Manufacture

the relative rate of the lapper and take-away con-

veyor. The lapped dough then passes through several

more sets of gauging rollers to bring the dough sheet

to the desired thickness prior to cutting.

0020 The repeated working of the dough in one direction

results in the accumulation of stress. If the dough

were cut at this point, the resulting pieces would

shrink to relieve the stress, and misshapen or dis-

torted products would result. Therefore, it is normal

to relax the dough after reduction and before cutting.

The relaxation is accomplished by transferring the

dough to a conveyor, still moving in the same direc-

tion, but at a slower speed.

0021 Once the dough has been relaxed, it passes on to

the cutting operation. Two different types of cutting

methods exist: reciprocating cutters and rotary

cutters. The reciprocating cutters are heavy block

cutters that stamp out one or more pieces at a

time. The cutter head (E) may have a dual action,

whereby the cutter drops first, followed by a docking

head or an embossing plate. The equipment operates

via a swinging mechanism so that the dough sheet

moves at a constant speed, the cutter drops and

moves with the dough, and then rises and swings

back to the original position. The second type of

cutter, the rotary cutter, consists of a rotating metal

cylinder. On the face of the roll are formed the desired

shapes with a sharp metal edge. As the cutter rotates

with the dough conveyor, the metal edges cut into the

dough sheet to form the product. The product pieces

are then conveyed into the oven.

0022 As a result of either cutting process, 20–60% of the

dough sheet remains as scrap. The scrap dough (F) is

lifted way from the cut dough pieces and returned

either to the mixer or to the sheeter. Return to the

mixer permits uniform incorporation of the scrap into

the dough mass. However, most systems route the

scrap back into the sheeter either along the full length

of the hopper or at the back side of the hopper. If

dough is incorporated behind the new dough, imper-

fections will be on the bottom side of the dough sheet

and will not be visible on the finished product.

Rotary Molding

0023 The principle of rotary molding is illustrated in

Figure 2. Three rollers are placed in a triangular

arrangement below a dough hopper. A roller, called

the forcing or feed roller (A), has deep grooves

designed to pull dough down from the hopper. The

dough is forced into the cavities of the engraved roller

(B) by the forcing roller. A scraper blade (C) is

mounted against the engraved roller to remove any

excess dough and return it to the hopper via the

forcing roller. Beneath the engraved roller is a

rubber-covered extraction roller (D) that serves to

drive the take-away belt (E). The extraction roller

applies pressure to the engraved roller via the belt,

causing the dough to adhere preferentially to the

conveyor belt. Dough pieces are dropped from the

take-away belt into pans or directly on to the baking

belt (F).

0024The rotary molding process is suitable only for dry,

crumbly doughs. This process offers advantages over

sheeting and cutting in that there is no scrap to re-

cycle, and there are very low labor requirements to

run the process.

Extrusion

0025There are two types of devices used in the production

of extruded cookies: wire-cut machines and bar/rout-

presses. Both systems are very similar in design

(Figure 3). A hopper is placed over a system of two

or three rollers (A) that force dough into a pressure

chamber (B). The rollers may run continuously or

intermittently to force dough out of the pressure

chamber at the die. For wire-cut cookies, the dough

is extruded through a row of dies, and a wire or blade

just below the die nozzle outlet. The cut dough pieces

fig0002Figure 2 Rotary molding process. See text for explanation.

Reproduced from Biscuits, Cookies and Crackers: Methods of

Manufacture, Encyclopaedia of Food Science, Food Technology and

Nutrition, Macrae R, Robinson RK and Sadler MJ (eds), 1993,

Academic Press.

(a) (b)

fig0003Figure 3 Extrusion process: (a) wire-cut machine; (b) bar/rout-

press. See text for explanation. Reproduced from Biscuits,

Cookies and Crackers: Methods of Manufacture, Encyclopaedia

of Food Science, Food Technology and Nutrition, Macrae R, Robin-

son RK and Sadler MJ (eds), 1993, Academic Press.

BISCUITS, COOKIES, AND CRACKERS/Methods of Manufacture 531

then drop into a conveyor band (D) for transport to

the oven. The wire usually moves only in one direc-

tion through the dough, opposite that of the con-

veyor. The wire-cut machines operate at rates of up

to 100 strokes per minute. Difficulties encountered

with this type of production are distortion of the

extruded dough piece during cutting, and inconsistent

placement or drop of the cut piece on to the conveyor.

(See Extrusion Cooking: Principles and Practice.)

0026 The design of the bar- or rout-press is very similar

to that of the wire-cut machine. The hopper rollers

and pressure chamber are essentially identical to their

wire-cut counterparts. Unlike the wire-cut machine,

the base of the pressure chamber has a die plate that is

inclined in the direction of the extrusion. A continu-

ous ribbon of dough is extruded from a nozzle, which

is shaped to impart the desired finished product

design. The dough ribbon can be cut into individual

pieces by a vertically operating guillotine before the

oven or after baking. If the product can be baked as a

continuous ribbon the dough is extruded directly on

to the oven band; otherwise, it is extruded and cut on

to a conveyor belt.

Baking

0027 The cookie and cracker industry relies almost exclu-

sively on band or traveling ovens to bake its products.

The band oven is essentially an insulated, heated

tunnel equipped with a continuous conveyor. The

ovens vary both in length (from 30 to 150 m) and in

band width (from 1.0 to 1.5 m). More modern ovens

frequently consist of a series of modular units or

zones. Each of the zones is equipped with its own

set of controls so that the temperature and air flow

may be controlled within that zone. The oven band is

typically continuous, passing on to a drive drum at

the end of the oven and returning underneath the

baking chamber to a tension drum at the feed or

input end of the oven. The chamber through which

the oven belt returns may or may not be enclosed.

Frequently, the oven band serves as the baking surface

for the product. Depending on the product type, the

oven band may be solid or any of a variety of open

wire-mesh types. The choice of mesh is a critical

factor in the process, as it affects the heat transfer at

the bottom of the product. This, in turn, can have a

marked effect on the quality of the finished product.

0028 There are three basic types of ovens: direct fired,

indirect fired, and fully indirect fired. Ovens are usu-

ally heated by the combustion of gas, although there

are a few manufacturers who use oil or electricity for

economic reasons. The most common type is the

direct-fired oven, in which gas is burned inside the

baking chamber itself. In these ovens, the burners are

placed across the width of the oven at regular inter-

vals, both above and below the oven band. In other

oven types, termed ‘indirect ovens,’ the gas or oil is

burned outside the baking chamber, and the heated

combustion gases are circulated into and throughout

the baking chamber. Indirect-fired ovens typically

have a single burner for each section. The hot gases

from the burner pass along pipes parallel to the length

of the oven, both above and below the oven band.

The products of combustion are circulated through-

out the baking chamber by large fans. Fully indirect

ovens are those in which the heat source is independ-

ent from the baking chamber and heat transfer occurs

via a heat exchanger. None of the products of com-

bustion circulate inside the baking chamber. This type

of oven is not common, except when oil is used as a

combustible material. If circulated, the products of

this type of combustion would impart an unaccept-

able flavor to the products.

Cooling

0029Products hot from the oven must be cooled prior to

packaging for several reasons: the products may not

be firm enough to withstand the packaging process

while warm, the packaging material may shrink

around a warm product, or the quality of the prod-

ucts would deteriorate if palletized while warm be-

cause the cooling rate across the pallet would be quite

slow.

0030The normal method of cooling products is to place

them on an open conveyor and transfer them along

a distance 1.5–2 times the length of the oven. The

products cool naturally in the ambient factory atmos-

phere. In a few cases, it is necessary to provide forced

air to aid the cooling process.

See also: Bread: Dough Mixing and Testing Operations;

Extrusion Cooking: Principles and Practice