Unit 3Wheat flour products

Wheat bread

Bread is one of the most common, convenient and inexpensive

foods, with leavened forms now the most popular in many countries

although flat breads remain very common in India and the Middle

East

the main ingredients are wheat flour, sugar, salt,yeast and water.

The major production methods used today in wholesale bread

production are the sponge and dough process, the straight dough

method and the no-time dough method 1

sponge and dough process

Bread preparation according to this process is described by

the process production line shown in Figure 1.

In the first stage, a portion of flour is mixed with water and

yeast and fermented for a certain period of time to produce a

sponge.

Subsequently, the balance of water and flour is added along

with other formula ingredients to the fermented sponge,

mixed to a fully developed dough, which is divided into pieces

to yield bread loaves of desired weights after baking. 2

The dough pieces are then rounded, given a relaxation

period by passing them on a belt, sheeted and shaped

into elongated dough pieces

placed into baking pans

transferred for proofing where they are proofed to

desired heights

baked

cooled

sliced

wrapped3

The packaged breads are distributed through retail

outlets and stores.

Their expected shelf life is about 4 days after baking in

stores and an additional 5 days in the home.

Although the bread is still edible and safe even after that

storage time, it becomes stale and thus loses its

customer acceptance due to organoleptic and

physicochemical crumb changes.

4

Fig 1 Flow chart of bread production by the sponge and dough process.

5

B. Straight Dough Method Breads made using this method are generally produced in

retail operations.

The doughs for breads and various small bakery products

are prepared in a single step by incorporating all formula

ingredients at the mixer.

The dough is mixed to a full gluten development and then

fermented to maturity without or with degassing by

punching during the fermentation step.

Then the fully fermented dough is divided and machined in

the same manner as in the sponge and dough process.6

C. No-Time Dough Process

This method is essentially a straight dough method

where the dough mixing is effected mainly mechanically

by the action of high-energy input of special mixers.

The mixing step can be further enhanced by addition of

reducing agents (L-cysteine, inactive dry yeast

preparations containing glutathione) or various

proteolytic enzymes.

The reaction of reducing agents has to be controlled by

the addition of suitable leaves of oxidants. 7

The fully mixed doughs are given short or no fermentation, then are divided, rounded, molded, proofed, and baked.

This method is especially suited for frozen dough manufacturing and retail bakeries.

8

Bread Production Equipment

The commercial production line detailing the equipment

used in the sponge and dough process is shown in Figure 1.

The mixer is generally a high-speed horizontal, which is

applied for both sponge and dough mixing.

The proofing room is a chamber with temperature and

humidity controls.

The divider is a device that divides the fermented dough

into dough pieces of desired weight. 9

The divided dough pieces are then rounded in a rounder.

The rounded dough is briefly relaxed in a overhead proofer, then

sheeted and molded by means of a molder into elongated dough

pieces, which are deposited into pans and transferred into a proof box.

The fully expanded (proofed) doughs are

baked in a tunnel oven

depanned

cooled

Sliced

packaged..

10

Types of Breads and Typical Formulas

A .White Pan Bread

The major type of bread manufactured in the United

States is white pan bread.

This type of bread is a standardized product and is

federally regulated in respect to its moisture content

(38% maximum) and enrichment.

11

White hearth breads are produced with or without lactic

acid fermentation, called sour by the trade.

The main difference between pan and hearth bread is in

the baking step:

hearth breads are baked on an open hearth

but pan in baking pans.

The type of heat transfer during hearth-baking leads to

formation of a solid, crisp, flavorful crust and other

attributes associated with this type of bread. 12

Functions of Bread IngredientsFlour-Structure.

1. Protein (gliadin and glutenin) and water form viscoelastic material, called gluten.

Gluten retains gas formed by sugar fermentation and contributes to structure of dough and bread.

2. Starch + water + heat forms a viscous paste that sets to a gel after baking.

During bread storage the starch crystallizes (retrogrades and contributes to firming (major part of staling) of breads.

3. Protein content for bread flour: 11.13%, 14% moisture basis.

13

Water-Hydration

1. Combines (hydrates) protein to form gluten.

2. Hydrates flour gums (pentosans) and mill-damaged

starch granules.

3. Solvent, dispersing agent, and medium for chemical and

biochemical reactions

4. Aids dough mobility.

14

Yeast-Leavening

1. Produces carbon dioxide, ethanol by fermentation of

fermentable sugars.

2. Conditions dough biochemically.

3. Forms flavor precursors (by-products of alcoholic

fermentation).

4. Rate of fermentation is controlled by temperature,

nutrient supply, water level, pH, sugar concentration,

salt, and level and type of yeast.15

Salt-Flavor Enhancer

1. Helps control fermentation.

2. Toughens dough by interaction with gluten.

Sugar-Energy Source for Yeast

1. Fermentable carbohydrates (fermentation).

2. Flavorresidual sugars (sweeteners), fermentation by-

products, Maillard-type compounds during baking.

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3. Crust colorresults of caramelization (sugars and heat)

and nonenzymatic browning (reducing sugar plus amino

group of proteins, amino acids, etc.).

4. Extends shelf life by increasing hygroscopicity due to

presence of residual sugars and tenderizing the crumb.

17

Shortening-Lubrication

1. Ease of gas cell expansion in doughs.

2. Lubricates slicing blades during bread slicing.

3. Extends shelf life.

4. Tenderizes crust.

18

Dairy products-Nutrition and Crust Color Enhancement

1. Protein (high in lysine) and calcium.

2. Flavor enhancement.

3. Crust color (browning reaction and caramelization).

4. Buffering effect in doughs and liquid ferments

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Enrichment-Nutrition

1. Standards of Identity require the following levels per 454 gram of bread:

Fe = 12.5 mg Niacin = 15.0 mg Ca (optional ingredient) = 600 mg Riboflavin - 1.1 mg Thiamine = 1.8 mg

20

Wheat gluten- Enhancement of Flour Strength

1. Increases dough strength (1% gluten increases protein content by 0.6%).

2. Increases water absorption [1% added gluten (flour basis) enhances absorption by 1.5% (flour basis)].

3. Improves dough mixing of fermentation tolerance. 4. Increases bread loaf volume. 5. Especially used in formulation of specialty breads.

21

Stability of Bakery Foods

A. Staling Bakery foods are perishablethey undergo

physicochemical, sensory, and microbial changes as indicated in Table 30. The generic term for this is ''staling."

It is advisable to follow the staling process with sensory tests, since flavor changes unrelated to firming often occur during storage.

In a simplified manner, starch gelatinizes during baking and amylose is leached out. Upon cooling the amylose component crystalizes and determines the fresh firmness of bread; amylopectin retrogradation proceeds slowly and causes firming during storage.

22

The process is heat-reversible because retrograded

amylopectin can be reverted to its amorphous state,

which reduces firmness.

23

Cookies

Cookies have great commercial appeal because they

are characterized by a formula high in sugar and

shortening and low in water.

In general, cookies are produced using soft wheat

flour that has a relatively weak gluten strength.

The weak gluten and the relatively high quantities of

fat and sugar in the dough allow plasticity and

cohesiveness without the formation of a strong

gluten network. 24

Minimal gluten development is also controlled by carrying

out the mixing process in two or even three stages.

The mixing step is critical to obtaining a dough of correct

consistency at the end of mixing.

Depending of the formulation, cookie dough tends to become

larger and wider as it bakes rather than shrinking like cracker

dough.

Control of this increase in size, known as spread, is a

continuous problem in process control.

A common way to classify cookies is by the way the dough is

placed on the baking band. 25

Pasta Pasta is a generic term used in reference to the whole

range of products commonly known as spaghetti, macaroni, and noodles.

Raw Materials for Pasta Products The pasta products macaroni, spaghetti, vermicelli, and

noodles are manufactured primarily from semolina, durum granulars, and flour produced from the milling of durum wheat.

These are the preferred raw materials for the production of superior quality pasta products.

26

To a lesser extent, farina and flour from common wheats are also used.

In addition, pasta can be processed from blends of various nondurum materials with durum semolina or flour.

However, blended products usually suffer a deficiency with respect to some quality attributes such as color or cooking quality.

The degree to which blending is practiced is usually dependent on wheat availability and price, competitive pricing, and consumer acceptance in a given market.

27

SemolinaSemolina is derived from the Italian word semola and the

French equivalent semoule. Pasta products are manufactured principally from the

three main milled products of durum wheat, namely semolina, durum granulars, and durum flour.

Farina and flour from common wheat are also used, but to a lesser extent in the United States than elsewhere.

For the production of good-quality pasta, the particle size of the semolina should not be too coarse nor too fine.

Semolina milling is unique in that the objective of the process is to prepare granular middlings with a minimum of flour production.

28

Water Water used in pasta products should be pure, have no

off-flavors, and be suitable for drinking. Since pasta can be processed below pasteurization

temperatures, the bacterial count of the water is directly related to the bacterial count of the finished product.

Consequently, only pure water of low total plate count should be used under these circumstances.

29

The recent advent of high-temperature and ultra-high-

temperature drying and microwave drying of pasta has

resulted in lower levels of microbial counts in pasta

products than previously experienced with conventional

temperature drying.

30

Pasta Production

A. Extrusion

Process of shaping items by forcing them through a die

In the continuous press, water is added to semolina to

give a dough moisture content of approximately 31%.

Uniform water/semolina mixing is carried out in a

counter rotating mixing chamber with vacuum applied

prior to extrusion.

31

Counter rotating mixing shafts limit balling of the dough,

and the applied vacuum reduces formation of small air

bubbles in the dough and limits oxidation of the

xanthophyll/lutein pigments.

The presence of air bubbles in pasta gives it a chalky

appearance and reduces its mechanical strength.

Pigment oxidation reduces the attractive yellow

appearance of the pasta and its subsequent consumer

appeal.32

The heart of the continuous press is the extrusion auger, which kneads the dough into a homogeneous mass prior to extrusion through a die.

Auger speed and temperature control of the dough contributes to the quality of pasta products.

Most modern presses are equipped with sharp-edged augers having a uniform pitch over this entire length.

The auger fits within a grooved extrusion barrel, which helps the dough move forward and reduces friction between the auger and the inside of the barrel during the extrusion process.

Extruder barrels are normally equipped with water-cooled jackets to hold the pasta temperature near 40°C during the extrusion process. 33

Figure 2 pasta production line.

34

B. Drying

Another critical step in pasta processing is drying.

Moist pasta from the extruder needs to be dried from

31% to approximately 12% moisture so that the product

will be hard, retain its shape, and store without spoiling.

Regardless of dryer design and temperature-humidity-

airflow control, problems can arise if the pasta is not dried

carefully .

If pasta is dried too rapidly, moisture gradients will occur,

which can cause the product to crack or check. 35

Checking can occur either during the drying cycle or as long as several weeks after the product has been packaged.

If large stresses are present due to improper drying, any change in relative humidity can result in a checked product.

It is essential that a pasta product be dried using a drying cycle tailored to meet that product's requirements.

36

Prior to 1974, conventional or low-temperature drying

(LTD) of pasta utilized drying times of approximately 16

hours for long goods and 8 hours for short goods.

High-temperature drying (HTD) was introduced into

commercial drying lines in 1974.

HTD raised drying temperatures from 55 to 75°C, which

resulted in shorter drying times (10 hours for long goods,

4.5 hours for short goods), lower bacterial counts, and

improved end-product quality37

More recently the evolution of pasta-drying technology has increased drying temperatures from 75 to 100°C and above.

These drying cycles are referred to as very-high-

temperature drying (VHTD) or ultra-high-temperature

drying (UHTD). The advantages of VHTD include significantly reduced

drying times (5.5 hours for long goods, 2.5 hours for short goods), improved end-product quality (Table 10), and reduced investment and operating costs.

A typical VHTD profile is shown in Figure 3.

38

Fig.3 long cut pasta moisture curve. M-moisture and t-drying time

39

C. Packaging

There are thousands of different sizes, shapes, and types

of packages in which pasta products may be sold .

However, they all perform the same basic functions, such

as keeping the product free from contamination,

protecting it from damage during shipment and storage,

and displaying the product favorably and with consumer

appeal.

40

Factors Influencing Pasta Quality A. Pasta Processed from Semolina/Farina

Although durum wheat semolina is the raw material of

choice for the production of pasta products, almost any

type of wheat may be used for producing pasta products

Studies have shown that the mill streams of durum were

more yellow than those obtained from bread wheats

and that they gave lower absorptions, which is an

advantage in pasta processing since less water has to be

removed in drying. 41

It was also shown that pasta processed from durum

wheat granular mill streams (GMS) with other bread

wheat GMS produces a better pasta product in

appearance and cooked properties than pasta processed

from the GMS of bread wheats alone.

Wyland and D'Appolonia studied the influence of drying

temperature and farina blending on pasta quality.

42

Blends were prepared that contained the durum

semolina and 0.5, 10, 20, 40, 60, and 100% of each class

of hard red spring (HRS) and hard red winter (HRW)

wheat farina.

Temperatures of 40, 60, 70, and 80°C were used in

drying the spaghetti after extrusion.

Results showed that increasing drying temperature

improved spaghetti color, increased cooked firmness,

and decreased cooking loss and cooked weight values. 43

Increasing the proportion of HRS and HRW wheat farina

in the farina-semolina blends brought about a decrease

in cooking loss, cooked weight, and spaghetti color.

Drying at the higher temperatures improved cooked

firmness.

Wyland and D'Appolonia concluded that a good quality

pasta product can be obtained by incorporating a certain

percentage of farina with semolina and that the quality

of these products can be improved with high-

temperature drying.44

Some countries such as Italy, France, and Greece place

restrictions on the addition of common wheat to durum

wheat pasta.

To monitor compliance with these restrictions, methods

have been developed to detect the presence of common

wheats in durum wheat products.

Sarwar and McDonald reported that sterol palmitate

content can be used to detect pasta adulteration, while

Barnwell et al. utilized reversed-phase high-performance

liquid chromatography for this purpose. 45

B. Pasta Processed from Sprout-Damaged Grain

Germination (sprouting) of grain before harvesting can

be a problem when rain and cool weather prevent or

slow down normal harvesting operations.

Pasta manufacturers are particularly sensitive to using

semolina milled from sprouted durum wheat in their

pasta-processing operations since it can affect end-

product quality.

46

Several studies have been conducted of the problems of

sprouting in terms of pasta quality.

Some general conclusions from those studies indicate

that test weight, kernel distribution, protein content,

milling performance, pasta color, and cooking quality

were not adversely affected by increasing sprout damage

(decreasing Falling Numbers).

The only major adverse effect appeared to be higher

semolina speck counts and spaghetti shelf stability. 47

It was also noted that sprout damage levels of 4.0% or

higher (Falling Numbers of 120 or less) resulted in pasta

products having high potential for checking and cracking

in storage.

Commercial manufacturers of spaghetti are concerned

not only with the problems mentioned above but also

with the tendency of spaghetti processed from sprout-

damage grain to stretch and fall off the rods during

drying. 48

Because of such concerns a number of U.S.

Research results indicate that pasta can be processed

utilizing semolina with Falling Numbers of 250 without

any apparent problems, so commercial manufacturer's

use of semolina with values of 350 and higher provides a

large margin of safety.

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C. Protein Quantity Versus Quality and Impact on Pasta Cooking Quality

The cooking characteristics of pasta products are the

ultimate tests in determining its quality.

In general, cooked pasta should be neither ''mushy" nor

"rubbery.“

It should retain its shape during cooking and be firm to

the bite (al dente).

Cooking time is important in terms of relative speed of

cooking and tolerance to overcooking. 50

Three major components of cooking quality assessment

include cooked weight, cooking loss, and cooked

firmness (texture).

Cooked weight (expansion volume) is a measure of the

water-absorbing capacity of the pasta during cooking and

should be three times the weight of the dry material.

Cooking loss is the percent solids lost to the cooking

water.

51

Cooked firmness determines the chewing characteristics

of pasta.

Cooked weight and cooking loss are relatively easy to

measure, but objective measurements of firmness and

stickiness has been the subject of study over many years.

Objective firmness tests are now used routinely for

cooked spaghetti, since it was shown they have a high

positive correlation (r = 0.812) with taste panel scores. 52

Research has also shown there is a significant positive

correlation between cooking quality and protein quantity

and quality.

In general, results show that higher protein and stronger

gluten protein in semolina produces pasta with better

overall cooking quality and tolerance to extended

cooking than do lower-protein, weaker-gluten products.

Feillet et al. recently cited a number of publications

dealing with the relationship between protein

composition and cooking quality. 53

Because of the positive correlation between stronger

gluten and improved pasta cooking quality, considerable

research has been directed towards the development

and interpretation of prediction tests related to gluten

quality.

Dick reviewed some of the tests used to predict durum

wheat and pasta quality.

54

In his review, Dick discusses such prediction tests as the

mixograph, farinograph, wet gluten, sodium dodecyl

sulfate (SDS) sedimentation, electrophoresis, and

chromatography and their relevance to pasta quality.

D'Egidio et al. analyzed 50 samples of 10 Italian durum

varieties by various technological and chemical tests,

obtaining 26 variables; a study of their value in predicting

pasta cooking quality suggested manual evaluation and

alveograph W value were the most efficient.

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Pasta Quality Evaluation No standard procedure exists

for the determination of pasta quality in terms of

appearance, color, and cooking quality.

Pasta quality is such a subjective matter that what is

acceptable in one country is not necessarily acceptable in

another.

Objective/subjective evaluation of pasta in laboratories

around the world evolved with the perceived needs of

the indigenous consumer. 56

Two examples reflect these differences.

In Italy the evaluation of pasta cooked stickiness,

firmness, and bulkiness is widely accepted and applied.

The test is performed on spaghetti of 1.60-1.65 mm or

1.70-1.75 mm diameter cooked under standard

conditions for 10-11 minutes according to the diameter.

57

At least three expert tasters assess the cooked product for:

1. Stickiness, which is the state of surface disintegration

of the cooked product, estimated by visual inspection,

with or without the aid of a standard reference pasta.

2. Firmness, which is the resistance of the cooked pasta

when chewed or flattened between the fingers or

sheared between the teeth.3. Bulkiness, which is the degree of adhesion of pasta

strands after cooking and is evaluated visually and manually. 58

By contrast, an evaluation procedure used in the United

States involves objective procedures that not only assess

the cooking quality of pasta but also that of the raw

materials used in the processing of the pasta.

Computer and statistical analysis of quality evaluation

data provides for overall quality rating within major and

minor fault parameters.

59

Major emphasis is placed on such quality traits as wheat

protein, semolina and spaghetti color, and spaghetti

cooked firmness.

Faults in any of these traits change the acceptability of

the sample quickly.

An advantage of this type of computer scoring system is

its flexibility for adjustment to meet changing quality

demands.

60

Conclusion

This topic provides an overview of factors that can

influence the processing and quality attributes of pasta

products.

Processing of pasta has evolved over many years from an

art to a highly sophisticated system of continuous raw

materials blending, mixing, extrusion, drying, and

packaging technology as we know it today.

61

In order to produce superior quality pasta, attention has

to be paid to the source and quality of raw materials

used; the quality of water mixed with the raw materials

to form the dough prior to extrusion; the quality of other

ingredients used in the dough mix; extrusion condition;

and drying conditions.

62

Taken in total, producing high-quality pasta is much

more complicated than it might first appear.

The roles played by the plant breeder, cereal chemist,

producer, miller, and grain market can have significant

influence on what the pasta manufacturers will use and

process in their plants.

This in turn will ultimately affect the consumer's

perception of the product as a desirable food.

63

Pasta companies have become interested in the

marketability of flavored pasta.

Ostrove pointed out that pasta products have become

more than simply a vehicle for sauces, but are available

in nearly every conceivable flavor and color as a

complement to any meat, fowl, or fish.

Dehydrated powders of vegetable flavors are generally

preferred because overall quality of the products tends

to be better. 64

Powders such as spinach, carrot, tomato, corn, broccoli,

and others as well as spices like saffron and flavors like

vanilla, mushroom, cayenne, and curry are becoming

more and more popular.

65