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these sensations, which are translated as ‘aroma.’

According to international praxis, flavors are divided

into three categories – natural, nature identical, and

artificial. (See Sensory Evaluation: Taste.)

0010 Natural flavors are mainly based on essential oils

and extracts where natural aromatic substances dom-

inate. In addition to the aromatic components, they

also contain constituent parts from the fruit, which

change during storage and can worsen the taste of the

drink. For this reason, these natural aromatic sub-

stances are sometimes strengthened with certain

identical aromatic substances that contain aromatic

components only and give a better stability to the

taste. (See Essential Oils: Properties and Uses;

Isolation and Production.)

0011 Nature-identical flavors are based on ingredients as

they occur in the natural fruit but which are produced

by chemical methods. They have a good solubility, a

reasonable price and a long shelf-life, which makes

them very suitable for soft drinks production.

0012 Artificial flavors contain chemicals that do not

occur in nature but have a familiar taste such as

vanillin, which has the taste of vanilla. This is an

ever-decreasing category and in time will be replaced

by nature-identical flavors.

Water

0013 Water is the main raw material in soft drinks. In

weight terms, a soft drink is 90% water. Water of

high quality is therefore important. It must be pure

and from a source approved by the regulatory author-

ities for drinking purposes. This means that it must be

free from biological and chemical pollutants, such as

bacteria and poisonous substances. It should also

have the cleanest taste and be least interactive and

microbiologically stable. The quality of water has an

impact on the quality and taste of the soft drink.

Sweeteners

0014 Sweeteners can be divided into two main categories:

nutritive or caloric sweeteners and nonnutritive or

low calorie sweeteners. We will discuss only the

sweeteners important for the soft-drink industry.

Sugar

0015 Sugar is a generic name for a class of sweet carbohy-

drates, including fructose, glucose, maltose, sucrose,

and lactose, that are readily soluble in water, color-

less, odorless, and usually crystallizable.

0016 For soft drinks, the most commonly used is sucrose,

which can be supplied either as a liquid or in

granulated form. Liquid sugar is dissolved granulated

sugar in water, normally at 67



Brix.

0017Sugar is an important ingredient for soft drinks, not

only because of its properties as a sweetener, but also

because it is highly nutritious and is an important

carrier of the fruit aromas. The different fruit aromas

require different quantities of sugar, depending on

which fruits are in the drink. This means that the

composition of the sugar solution is critical if the

drink is not to be too ‘thin’ or taste too sugary. Two

other types of sugar are found in fruit – fructose (fruit

sugar) and glucose (grape sugar). Fructose is 50%

sweeter than ordinary sugar, but contains the same

number of calories per gram. A smaller quantity of

fructose gives the same sweetness. It is therefore

sometimes used to reduce the number of calories.

Honey is another less commonly used sweetener

that also contains glucose and fructose. (See Carbo-

hydrates: Classification and Properties; Glucose: Pro-

perties and Analysis; Honey; Lactose; Sucrose:

Properties and Determination; Dietary Importance.)

Nonnutritive Sweeteners

0018In the past, low-calorie drinks were only marketed as

diabetic products. Now, they have become increas-

ingly popular for both weight-watching and eco-

nomic reasons. Low-calorie drinks are an important

part of the total soft-drink market. When using a

nonnutritive sweetener, it is important to have up-

to-date information about the food regulations

concerning this subject, as they differ greatly from

country to country and are subject to many changes.

0019A sweetener has to comply with the following

standards, assuming it is allowed by the food laws

concerned:

0020It should not be hazardous to health.

0021It should give no off-taste.

Saccharin

0022Saccharin is a synthetic, white, crystalline powder, of

formula C

CONHSO

, which, in its pure state, is

550 times sweeter than sugar. In its commercial form,

saccharin is estimated to have a sweetening power

375 stronger than that of sugar.

0023The only synthetic, nonnutritive sweetener pres-

ently allowed in most countries in soft drinks is sac-

charin. It has been in use continuously since 1900.

The use of saccharin is mostly restricted to special

dietary foods and beverages appropriately labeled as

such.

0024For several years, saccharin has been under investi-

gation as a potential cause of cancer. Warning labels

were required on saccharin-containing foods. The

most recent studies indicate that it is a weak carcino-

gen in laboratory animals but does not, in moderate

use, present an increased cancer risk in humans. The

SOFT DRINKS/Chemical Composition 5347

recommended acceptable daily intake (ADI) is 1 g

per person per day. The tolerance level for soft drinks

is 0.4 mg ml

1

. This is an interim tolerance level,

and safety studies are continuing. (See Cancer:

Epidemiology; Carcinogens: Carcinogenic Substances

in Food: Mechanisms; Carcinogenicity Tests;

Saccharin.)

Cyclamate

0025 Cyclamate is an odorless, white crystalline powder.

The name usually denotes either calcium cyclamate or

sodium cyclamate, both of which are salts of cyclo-

hexylsulfamic acid. They have a very sweet taste, with

about 30 times the sweetening power of sucrose.

0026 After saccharin, cyclamate was the most commonly

used sweetener until it was banned in the USA in

1970, after which many countries followed suit.

Much of the scientific community doubted that

cyclamate was hazardous but for new FDA approval

more very costly research is needed and people would

rather concentrate on other sweeteners. (See Cycla-

mates.)

Aspartame

0027 Aspartame is a sweetener made from the natural

amino acids l-aspartic acid and l-phenylalanine.

l-Aspartic acid is tasteless, and l-phenylalanine is

slightly bitter, so the taste of aspartame could never

have been predicted. Aspartame was discovered by

accident in the laboratories of the Searle Company in

1965 and was first approved for use in food products

in Canada 15 years later. In 1983, approval was

granted by the FDA, followed by many authorities

in other countries. The only negative aspect of aspar-

tame is that it can be hazardous for people who suffer

from phenylketonuria, an inherited disorder that can

lead to brain damage in those exposed to phenylalan-

ine. This disease is rare, however. Since aspartame is

so sweet (about 200 times sweeter than saccharin),

only a small quantity is needed, and it is therefore put

into the same category as energy-free sweeteners. The

calorie content can be reduced by 95% compared

with corresponding drinks sweetened with saccha-

rates. During digestion, aspartame is treated as pro-

tein, and so diabetics are able to eat and drink food

sweetened with aspartame. (See Amino Acids: Proper-

ties and Occurrence; Aspartame; Protein: Chemistry;

Food Sources; Determination and Characterization;

Requirements; Functional Properties; Interactions

and Reactions Involved in Food Processing; Quality;

Digestion and Absorption of Protein and Nitrogen

Balance; Synthesis and Turnover; Deficiency; Heat

Treatment for Food Proteins; Sources of Food-grade

Protein.)

Acesulfame-K

0028Acesulfame-K was developed by Hoechst in 1973,

was approved by the British Food Regulations in

1983, and has since been adopted in countries like

Germany, Belgium, and Denmark. Acesulfame-K is

not metabolized at all and therefore has no calorific

value. It is absorbed quickly in the intestine, and

excretion is similarly fast. (See Acesulfame/Acesul-

phame.)

Stevia (

Stevia rebaudiana Bertoni

)

0029Stevia contains natural compounds, especially stevio-

side and rebaudioside A, that are estimated to be

150–400 times sweeter than saccharose. Used for

centuries in parts of South America, stevia has been

discovered in recent years by much of the calorie-

conscious modern world. It is now widely and legally

consumed by millions of people, from South Korea,

Israel, and the People’s Republic of China, but no

country has done more to demonstrate stevia’s dietary

and economic potential than Japan, where the herb

and its extract have been used since 1970s.

0030The Japanese, having subjected stevia extract to

extensive safety testing and found it without health

risk, now incorporate it in numerous food products,

including soft drinks.

Sucralose

0031Sucralose was approved by the FDA in 1998 for use in

a wide variety of food products including soft drinks.

Sucralose is a low-calorie, high-intensity sweetener

that is about 600 times sweeter than sugar. It is sold

under the brand name of ‘Splenda.’ Sucralose and

sucrose (sugar) have been shown to have similar

taste and flavor profiles.

0032A number of other fascinating low-calorie sweet-

eners are currently undergoing safety evaluations for

future use. These include alitame, a compound simi-

lar to aspartame that is remarkably 2000 times

sweeter than sucrose, and various naturally occurring

plant derivatives, such as stevia and thaumatin.

Acids

0033Acids are used as pH buffers in beverages and to

impart an astringent taste that offsets the sweetness

of the sugar and enhances or complements the associ-

ated flavor. Thus, the characteristic flavor of a bever-

age is developed in part through proper acidulation.

Acids also help in preventing microbiological spoilage.

0034All acids used in beverages must be ‘edible grade’

or ‘food grade.’ Those commonly used are citric-,

phosphoric-, and malic acid. Each has the property

of being weak and nonharmful at the concentrations

5348 SOFT DRINKS/Chemical Composition

used. Inherent chemical differences in the various

acids impart different taste characteristics, and

in substituting one acid for another, these differ-

ences have to be kept in mind. Table 2 shows

the acidification strength of some acids relative to

citric acid.

0035 The kind of acid and the concentration employed

are very important for adjusting the flavor of the

beverage.

Citric Acid

0036 Traces of citric acid are found in numerous plants and

animals, because it is a nearly universal intermediate

product of metabolism. Large amounts of the acid are

found in the juice of citric fruits. Fermentation of

sugar by Aspergillus niger is the chief commercial

source of the acid. Since it is a natural ingredient of

citrus fruits, it adapts itself well to beverages with

such a flavor.

0037 Citric acid may be used in the anhydrous form or

containing one molecule of water. It occurs as color-

less, translucent crystals or as a white, granular-to-

fine crystalline powder. It is odorless with a strong

acid taste, and the hydrous form is efflorescent in dry

air. (See Citrus Fruits: Types on the Market; Compos-

tion and Characterization; Oranges; Processed and

Derived Products of Oranges; Lemons; Grapefruits;

Limes.)

Phosphoric Acid

0038 Phosphoric acid is a very popular acidulant because

of its strength and very low cost; in fact, it is the

cheapest acid used in the industry. It is used mainly

in cola-type beverages, in which it improves not only

the acid taste but also the typical cola bite.

Malic Acid

0039 Malic acid is found in fruits such as apples, apricots,

and cherries. The food industry finds the tartness of

this additive a valuable flavor booster for candies,

jams, ice creams, fruit, and soft drinks. (See Ice

Cream: Methods of Manufacture; Properties and An-

alysis; Dietary Importance; Microbiology; Jams and

Preserves: Methods of Manufacture; Chemistry of

Manufacture; Sweets and Candies: Sugar Confec-

tionery.)

Carbon Dioxide

0040Carbon dioxide is present in the air in very small

quantities (approx. 0.03%) and is about 1.5 times as

dense as air. It is a colorless, odorless, and tasteless

gas and has a good solubility in water. When confined

within a suitable pressure vessel, CO

can exist as a

solid, liquid, or gas.

0041When drinking a carbonated beverage, the devel-

opment of CO

in the mouth, because of the warmth

of the throat, causes a light anesthetic effect on the

taste buds, which diminishes and sometimes even

stops the sensation of thirst. Carbon dioxide makes

the drink more refreshing through its stimulation of

the mouth’s mucous membranes. This adds to the

sensation that the soft drink is colder than it actually

is and also brings out the aroma.

0042Carbon dioxide also checks microbiological

growth, which means that the product lasts longer.

Many bacteria die after a certain time in carbonated

drinks. This applies equally to carbonated soft drinks,

mineral water, and beer. There are good grounds

for advising people, for hygienic reasons, to drink

carbonated drinks, particularly in hot climates. (See

Beers: History and Types.)

Preservatives

0043The low pH value of soft drinks is good for the life

of the product from a microbiological point of

view since bacterial growth is checked. Carbon

dioxide also has a positive effect. Sometimes, how-

ever, this is not enough, and preservatives have to

be used.

0044Preservation denotes any method that extends

the shelf-life of a product. Methods such as pick-

ling, freezing, drying, sterilizing, smoking, or the

addition of a chemical agent with a bactericidal ac-

tivity all have undesirable effects on the odor, taste,

or digestibility of the foodstuffs. (See Drying:

Theory of Air-drying; Freezing: Principles; Pickling;

Smoked Foods: Principles; Production; Sterilization

of Foods.)

0045The history of the soft-drink industry has demon-

strated that beverages are good nutrient media for

certain acidophilic microorganisms, particularly

yeasts. It has been demonstrated by various investi-

gations that over 90% of all cases of microbiological

spoilage of soft drinks are caused by yeast. Spoilage of

soft drinks by yeasts is evidenced by visible sediment,

gas formation, off-odor, off-taste, and changes in

beverage color and clarity.

tbl0002 Table 2 Acidification strength (%) relative to citric acid

Type Strength (%)

Citric acid 100

Tartaric acid 93

Malic acid 100

Ascorbic acid 43

Lactic acid 60

Phosphoric acid 125

SOFT DRINKS/Chemical Composition 5349

0046 To prevent soft drinks spoiling, it is necessary to

use good manufacturing practices to control the

growth of microorganisms. High hygienic standards

should be applied during production, together with

the creation of unfavorable environments for micro-

organisms, such as acidifying, cooling and pasteuriz-

ing, and, if necessary, chemical preservation. Only

small quantities of preservatives are allowed in soft

drinks. The preservatives allowed are subject to the

food and drugs laws of the different countries in-

volved. However, chemical preservation alone is not

sufficient. Therefore, these types of products must

always be pasteurized.

0047 The most common preservatives are sodium benzo-

ate (sodium or potassium sorbate can be used as a

replacement) and sulfur dioxide, particularly if it is

required to prevent the color darkening.

Benzoic Acid

0048 Benzoic acid or benzene-carbonic-acid is a monobasic

aromatic acid, moderately strong, white crystalline

powder, very soluble in alcohol, ether, and benzene,

but poorly soluble in water (0.3 g of benzoic acid in

100 g of water at 20



C).

0049 Benzoic acid has the advantage that it does not

affect the odor or taste of the soft drink, if used in

small quantities. The preserving quality of benzoic

acid is based on its activity to delay the multiplication

of several groups of microorganisms, which, however,

are not killed by this product. The low solubility

of benzoic acid in water complicates its applica-

tion in products containing large amounts of water.

Therefore, the water-soluble salt sodium benzoate is

used.

0050 This product, which is the salt of benzoic acid,

has no preserving activity by itself. Therefore, after

addition of sodium benzoate, the acidity of the soft

drink is increased (pH < 3.5), with the result that

free undissociated benzoic acid is formed, which has

a preserving property. In an alkaline environment,

benzoic acid is split into ions and thus loses its pre-

serving activity.

0051 Sodium benzoate is the sodium salt of benzoic acid

used as a white crystalline or amorphous (without

crystal structure) powder, very soluble in water (66 g

of sodium benzoate in 100 g of water at 20



C) but

poorly soluble in alcohol.

Sorbic Acid

0052 Sorbic acid, potassium sorbate, and calcium sorbate

are novel, highly efficient, safe, and nonpoisonous

food preservatives. They are the substitute for the

benzoic acid as a traditional preservative. Sorbic

acid, potassium sorbate, and calcium sorbate

approved worldwide are often now successfully used

as standard products in many branches of the food

industry. As they are acidic preservatives, it is better

to use them at pH 5–6.

0053Sorbic acid, potassium sorbate, and calcium sor-

bate are unsaturated fatty acids and salts of unsatur-

ated fatty acids, which participate in the normal fat

metabolism in human body and are oxidized into

carbon dioxide and finally water. They do not accu-

mulate in the human body. (See Fatty Acids:

Properties; Trans-fatty Acids: Health Effects.)

Sulfur Dioxide

0054The preservative effect of sulfur dioxide, like benzoic

acid, is greatly increased by a corresponding decrease

in pH. Undissociated H

is responsible for most

of the preservative action. In contrast to sodium

benzoate, sulfur dioxide kills microorganisms instead

of delaying their growth.

0055Sulfur dioxide also combines regularly with many

compounds present in juices and soft drinks, and the

combined SO

exhibits little or no preservative effect.

This must be taken into account when deciding on the

levels required to preserve soft drinks, but it must be

remembered that the legal limit is often based on the

total free and combined SO

in the product. Sulfur

dioxide can be added as the salt of sodium or potas-

sium metabisulfite or as a solution of sulfurous acid.

This compound gives off SO

gas and therefore must

be stored in airtight containers. A disadvantage of the

use of SO

as a preservative is its relatively bad taste

at a dosage above 10 mg l

1

.(See Sodium: Properties

and Determination.)

Coloring Matter

0056Food that looks beautiful when served, e.g., nicely

served and has a beautiful color, affects the consumer’s

experience of taste positively. Color is an important

signal of identification that complements the label and

is a dominant factor in consumer acceptance of a

beverage. An attractive, natural-looking color tempts

one to taste and consume a beverage.

0057Before the mid-1970s, many more colorings were

used than is the case today. The soft-drinks industry,

itself, has reduced the number of coloring matters

used. However, the pure fruit-juice content of soft

drinks makes it difficult to create the right colors.

For this reason, identical coloring agents of the sort

found in the fruits are used extensively. The most

important is b-carotene, which is the predominant

coloring agent in carrots and oranges.

0058Brown drinks are colored with caramel. Different

drinks require caramel with different qualities. This

5350 SOFT DRINKS/Chemical Composition

can be achieved by having different nitrogen com-

pounds present during the heating phase of caramel

production.

0059 Colors can be either natural or artificial. Natural

colors include: anthocyanins (from berries and

grapes), caramel, xanthophyl, and carotenoids. Arti-

ficial colors include: tartrazine NS, yellow FCS, and

Amaranth AS. (See Caramel: Properties and Analysis;

Carotenoids: Occurrence, Properties, and Determin-

ation; Colorants (Colourants): Properties and Deter-

mination of Natural Pigments.)

0060 Legal requirements for colors used in soft drinks

differ from country to country, as do the required

declarations for each country. The overall move

toward more health-oriented products has increased

requests for natural colors. When using natural

colors, ascorbic acid has to be added to improve the

stability (better resistance to light). A positive side-

effect of using ascorbic acid is a reduced incidence of

can corrosion. The disadvantages of natural colors

are the high cost, the complication of the manufactur-

ing process, and the poor stability. (See Ascorbic

Acid: Properties and Determination.)

Antioxidants

0061 Antioxidants prevent reactions, which destroy aro-

matic substances. The most common antioxidant is

ascorbic acid, i.e., vitamin C. Sulfur dioxide, named

above as a preservative, is also used as an antioxidant.

(See Antioxidants: Natural Antioxidants; Synthetic

Antioxidants.)

Other Additives

0062Emulsifying agents, stabilizing agents, and thickening

agents are all used to ensure that the contents of

the drinks remain evenly distributed. The fat peel oil

from oranges, for instance, would otherwise form

lumps and create a ring around the neck of the bottle.

Since the oil is the carrier of the aroma and sometimes

the coloring agents, the drink would soon become

uneven in taste and look unattractive. Examples of

stablizing agents and thickening agents are pectins,

which are obtained from citrus fruits or apples,

and alginates and carragheen, which are obtained

from algae. (See Emulsifiers: Organic Emulsifiers;

Phosphates as Meat Emulsion Stabilizers; Uses in

Processed Foods; Pectin: Properties and Determin-

ation; Food Use; Stabilizers: Types and Function;

Applications.)

0063Soft drinks generally contain no significant

amounts of protein, fat, fiber, or vitamins. The

small amounts of minerals (calcium, iron, magne-

sium) and trace elements (copper, manganese, zinc,

fluoride) that may be naturally present will vary

depending on the local water supply. However, some

soft drinks now contain added vitamins (C, niacin,

, biotin, pantothenic acid, and folic acid) and/

or increased levels of potassium (from added juice).

tbl0003 Table 3 Calorie, nutrient, and ingredient content of major types of soft drinks

Flavor types Calories Carbohydrates

(gml

1

)

Total sugars

(gml

1

)

Sodium

(mgml

1

)

Potassium

(mgml

1

)

Phosphorus

(mgml

1

)

Caffeine

(mgml

1

)

Aspartame

(mgml

1

)

Regular

Cola 0.4–0.5 0.10–0.12 0.10–0.12 0–0.08 0–0.05 0.11–0.21 0.08–0.13 0

Caffeine-free cola 0.4–0.5 0.10–0.12 0.10–0.12 0–0.08 0–0.05 0.11–0.21 0 0

Cherry cola 0.4–0.5 0.10–0.12 0.10–0.12 0–0.04 0–0.03 0.13–0.15 0.03–0.13 0

Lemon–lime (clear) 0.4–0.5 0.10–0.12 0.10–0.12 0–0.15 0–0.01 0–0.003 0 0

Orange 0.5–0.6 0.11–0.14 0.11–0.14 0.04–0.12 0–0.05 0–0.17 0 0

Other citrus 0.3–0.5 0.08–0.14 0.08–0.14 0.03–0.14 0–0.33 0–0.003 0–0.18 0

Root beer 0.4–0.5 0.10–0.14 0.10–0.14 0.01–0.17 0–0.05 0–0.05 0 0

Ginger ale 0.3–0.4 0.08–0.11 0.08–0.11 0–0.08 0–0.01 0–trace 0 0

Tonic water 0.3–0.4 0.08–0.10 0.08–0.10 0–0.03 0–0.01 0–trace 0 0

Other regular 0.4–0.6 0.10–0.15 0.10–0.15 0–0.12 0–0.06 0–0.26 0–0.12 0

Juice added 0.4–0.6 0.10–0.14 0.10–0.14 0–0.06 0.08–0.33 0–0.21 0 0

Diet

Diet cola <0.03 0–0.003 0 0–0.17 0–5.0 0.07–0.16 0–0.16 0–0.53

Caffeine-free diet cola <0.03 0–0.003 0 0–0.2 0–10.0 0.07–0.16 0 0–0.53

Diet cherry cola <0.03 0–<0.001 0–trace 0–0.02 1.5–5.0 0.07–0.11 0–0.13 0.50–0.52

Diet lemon–lime <0.03 0–0.003 0 0–0.26 0–6.9 0–trace 0 0–0.53

Diet root beer <0.06 0–0.013 0 0.11–0.28 0–3.0 0–0.05 0 0–0.58

Other diets <0.2 0–0.05 0–0.05 0–0.27 0.3–10.1 0–trace 0–00.19 0–0.57

Club soda, seltzer, and

sparkling water

0 0 0 0–0.27 0–0.5 0–0.003 0 0

Diet juice added <0.1 0.003–0.017 0.003–0.017 0–0.06 0–0.3 0–0.17 0 0.38–0.53

SOFT DRINKS/Chemical Composition 5351

Table 3 shows the calorie, nutrient, and ingredient

content of major types of soft drinks.

0064 Sodium and potassium values do not include the

levels contributed by water, which will vary

depending on geographic location and season. Most

soft drinks are very low in sodium, and some are

sodium-free. (See Potassium: Properties and Deter-

mination.)

See also: Ascorbic Acid: Properties and Determination;

Caramel: Properties and Analysis; Carbohydrates:

Classification and Properties; Citrus Fruits: Types on the

Market; Colorants (Colourants): Properties and

Determination of Natural Pigments; Glucose: Properties

and Analysis; Lactose; Potassium: Properties and

Determination; Preservatives: Classifications and

Properties; Saccharin; Sensory Evaluation: Aroma;

Taste; Sodium: Properties and Determination; Sucrose:

Properties and Determination; Dietary Importance

Further Reading

Colonna WJ, McGillivray T, Samaraweera U and Torgeson

T (1996) Proceedings Conference of The Sugar Process-

ing Research Institute.

Henkel J (1999) Sugar Substitutes: Americans Opt for

Sweeteners and Lite. USA: FDA.

Production

C Matthews, NET International, Gloucester, UK

This article is reproduced from Encyclopaedia of Food Science,

Introduction

0001 Soft drinks have been consumed, in one form or

another, for thousands of years from the first time it

was discovered that the addition of acid materials

such as lemon juice and/or the incorporation of only

5% of alcohol from fermentation of grape and other

juices resulted in the preservation of dietary water.

Although milk, wine, and beer have all been around

for well over a thousand years, and tea and coffee for

many centuries, carbonated soft drinks are approxi-

mately 200 years old, dating from the commercial

production of seltzers and sodas in the late 1700s.

Revitalization of the squashes, syrups, or concen-

trated still soft drinks market has been facilitated

in the last few decades by the introduction of aseptic

packaging techniques, enabling continuous filling of

juices and ready-to-drink squash-type products into

foil laminates, pouches, and cartons. Some would

argue, with justification, that this is a completely

new sector of soft drinks made possible by advances

in production and packaging technology.

0002The production of soft drinks falls into three main

areas of activity:

0003Supply, handling and treatment of ingredients

(including the water supply).

0004Blending of these ingredients and the processing of

the blends/combinations so achieved.

0005Packing or packaging of these blended ingredients

into the finished product for distribution and sale

(this may involve a further processing step, as in

the case of aseptic filling or dilution, and carbon-

ation, as with carbonated soft drinks).

Supply, Handling, and Treatment of

Ingredients

0006Most ingredients will be supplied in a user-friendly

and stable form by the ingredient manufacturers or

suppliers, with detailed specifications and usage in-

structions. During the time these ingredients are held

at the site of the soft drinks manufacturer it will

simply be necessary for them to be stored according

to the storage instructions of the supplier and used

within shelf-life. Some of the storage conditions and

shelf-lives of usually encountered raw materials will

be found in Table 1.(See Storage Stability: Param-

eters Affecting Storage Stability.)

0007It is normally the responsibility of the quality con-

trol department to approve the quality of all incoming

materials and insure correct rotation for use prior to

expiry of shelf-life.

0008This leaves the main ingredient in soft drinks –

water – which requires special treatment to insure

sensory, microbiological, and physical acceptable

quality. The chemical quality of water may be char-

acterized as follows.

0009Appearance free from sediment, color, and cloud.

0010Taste free from taint or materials such as chlorine,

hypochlorite, or nitrates which are capable of

reacting with other components or materials (e.g.,

cans).

0011Free from toxins of any description.

0012Free of water hardness which can destabilize fruit

colloidal suspensions via the calcium and magne-

sium which cause water hardness. (See Quality

Assurance and Quality Control.)

This is achieved in a soft drinks production plant in a

number of ways and the following list comprises the

main parameters covered in the specification (and

5352 SOFT DRINKS/Production

hence treatment, where necessary) of water: appear-

ance; pH; total dissolved solids; total hardness;

alkalinity; nitrogenous compounds; chloride; organic

content; microorganisms; phosphate; silicates; trace

metals; chlorinated compounds.

Water Treatment

0013 Chemical coagulation is widely used in soft drink

production plants as a means of removing unwanted

impurities. The incoming water passes into a reaction

vessel where coagulating chemicals are added. The

reaction products and impurities are precipitated

and form a gelatinous sludge through which the

treated water flows to a clear zone at the top of the

vessel. Since small particles of the flocculant will

travel with the treated water, it is normal practice to

pass water treated in this way through a sand-bed

filter. A typical system of this type is illustrated in

Figure 1.(See Water Supplies: Water Treatment.)

0014 The types of coagulants used are ferrous sulfate,

aluminum sulfate, and Lapofloc PAC (a solution of

polyaluminum chloride).

0015 Chlorination is the next stage in the treatment of

water. Free chlorine is usually used as the sterilizing

agent at a level of about 6–8mgl

1

of chlorine after

the sand filter to insure completion of the reaction.

Either chlorine gas or hypochlorite solution may

be used. Where ferrous sulfate is employed as the

coagulant, free chlorine oxidizes the ferrous salt

to ferric salt and is usually added to the coagulation

tank where the residence time may be included as

part of the contact time necessary for sterilization.

Where aluminum sulfate is used, the chlorine is

usually added after the sand filter and residence

time in the coagulant tank is not part of the contact

time.

0016 Organic matter, sulfites, nitrites, and ammonia (or

its compounds) absorb or react with chlorine and the

bactericidal action of chlorine will not be effected

until after these reactions have taken place. Chlorine

is best added to the coagulation tank or immediately

after, since contact with raw, untreated water

containing humic organic substances produces tri-

halomethanes (THMs) which would result in an un-

pleasant taint to the water if present in quantities in

excess of 100 mgl

1

. Via the chlorination process

all impurities will be oxidized, removing all taste

and odor, including those due to phenol and its

derivatives.

0017The next stage in the process is the dechlorination

of the water after sterilization by passing the water

through an activated carbon filter which is housed in a

vessel similar to that of the sand filter (Figure 1). The

quantity of carbon will be selected to achieve a con-

tact time of approximately 5 min with the water,

removing all of the chlorine and any remaining

organic molecules. Carbon filters are fitted with

steam injection at the base to allow sterilization

when required to reduce the gradually increasing

microbiological contamination from its use.

0018Quality control on a continuous basis of all aspects

of the process must be effected to insure optimum

performance of the process. In particular it must

always be able to indicate an imminent breakdown

of the carbon bed when it requires regeneration.

0019The above process is the classical procedure for

water treatment. There are, however, other methods

of either total treatment or treatment for specific

requirements of the water. They are as follows:

0020Ion exchange will perform softening; dealkaliza-

tion; nitrate removal; organic compound removal.

0021Reverse osmosis will effect removal of high levels

of dissolved solids, resulting in a water which may

be used directly or further treated for carbonated

soft drinks production.

0022Ultrafiltration removes colloidal substances and

may be substituted for the polishing filter in a

conventional process.

0023Alternative sterilization processes include ultra-

violet light, ozonization, and micropore filtration.

tbl0001 Table 1 Storage conditions of soft drink raw materials

Material Storage conditions Recommended shelf-life

Fruit

Frozen Below 18



C 2–3 years

Preserved Ambient 3–9 months

Aseptic c.4



C Up to 6 months

Sugar syrup Dependent on concentration

Some may be stored at ambient 48 h

Glucose syrup (GS)/high-fructose GS 35



C 48 h–1 week

Citric acid solution Ambient 1 week

Volatile and natural flavoring materials 4



C 3–6 months

Nature-identical and artificial flavoring materials Dark UK; ambient 6–12 months

Water Ambient On demand

SOFT DRINKS/Production 5353

Blending and Processing of Key

Ingredients in Soft Drinks

0024 There are two basic methods of manufacture of soft

drinks; these are the single batch production and

continuous production. Batch manufacture is the

process where a tank with a capacity of up to

25 000 may be employed to manufacture the product

and/or intermediate syrup to feed the filling line over

a period of time. Continuous production utilizes two

tanks of only 50–100 l each, with a computer, con-

tinuously making one batch after another in a type of

tandem operation. The main advantages of the latter

system are associated with line problems and interup-

tions, particularly where a heat treatment is part of

the process, since only the 50 or 100 l of product

already manufactured will be affected, and may easily

be ‘ditched’ without significant economic conse-

quences. In the case of batch manufacture, however,

the 25 000 l of product or intermediate syrup will

either remain under nonoptimum conditions or, at

worst, continue to be heat-processed (with a return

to the batch tank) for the duration of the line down-

time.

0025 In each case the steps and safeguards it is necessary

to take in the production process are the same

and will be covered in the same way. The schematic

representation of the production of a soft drink is

shown in Figure 2. It can be seen that the processing

required for the production of a soft drink involves

blending the individual ingredients with heat treat-

ment and/or homogenization where necessary. In

reality all ingredients are not added separately to the

main blending vessel, since this would cause signifi-

cant logistical problems for items that are difficult to

handle, such as solid sugar (dissolution problems) or

thickeners or stabilizers (localized viscosity build-up,

lack of powder wetting). There are basically four

streams of ingredients:

0026Colors, flavorings, etc.

0027Sugars (i.e., all carbohydrates).

0028Fruit materials.

0029Citric acid, stabilizers, emulsifiers, etc. (this stream

utilizes a premix blending vessel with a signifi-

cantly increased blending power-to-volume ratio

for difficult-to-dissolve/disperse ingredients).

0030Many soft drink production sites are now convert-

ing to tanks located on load cells so that the vessel

may be tared and ingredients weighed directly into

them.

0031If liquid carbohydrates are being used, these may

be added directly from their optimum storage pos-

ition to the main blending vessel via an inline sieve or

Backwash water

storage tank

(optional)

Chlorinated water

storage tank

(optional)

Sand-bed

filter

Carbon-bed

filter

Polishing

filter

Sludge

blow-down

Raw-water

inlet

Chemical

feed

pumps

Chemical feed

storage tanks

fig0001 Figure 1 Typical water treatment process in the production of soft drinks.

5354 SOFT DRINKS/Production

filtration system to remove any small particles. If

solid sugar is used, a simple syrup must be prepared

of the sugar and water at approximately 50



C to aid

dissolution; this is then cooled before addition to the

main blending vessel. All other ingredients are added

to the carbohydrate syrup in the blending vessel in an

order which takes into account their chemical reactiv-

ity with other ingredients. For example, sodium

benzoate must always be added prior to the citric

acid, since benzoic acid is only sparingly soluble in

acid solution. Certain clouding agents and stabilizers

must not be added in close proximity to a flavoring

that contains a high level of an alcohol as solvent,

since they will interreact.

003 2 With a high level of carbohydrate or thickening

agent in the syrup in the main blending vessel, it is

very easy to entrain air with too much vigorous agi-

tation, and this would result in fobbing during filling,

particularly of carbonated products. As long as agita-

tion has not been excessive, then 2 h standing after

mixing, with gentle agitation to keep all ingredients

evenly dispersed, will be sufficient to allow entrained

air to escape. This gentle agitation should be con-

tinued for the duration of any pumping or direct

bottling so that particulate materials, such as fruit

comminute, are evenly dispersed throughout the

liquid.

Homogenization

0033This process is used for many fruit-containing

concentrates as part of the finished beverage manu-

facture enroute to the bottling line and for inter-

mediate syrup processing for some fruit-containing

carbonates and ready-to-drink still beverages. The

process is a means of reducing the particle size of

particulate matter (e.g., fruit comminute) by means

of energy input resulting in a more stable suspension

and hence better appearance. The conditions which

are normally used are 1000–3000 psi at ambient

temperature.

Carbonation

0034The simplest type of carbonator is a pressure vessel in

which the liquid and the carbon dioxide are allowed

to stay in contact with each other. There are three

basic ways to achieve this: (1) vessel partly filled with

liquid and pressurized with carbon dioxide; (2) liquid

falling through carbon dioxide in a pressurized con-

tainer; (3) carbon dioxide bubbling through liquid

in a pressurized vessel or pipeline. All carbonators

operate on one or more of these principles.

0035One of the essential requirements of a production

carbonation system is control over the degree of sat-

uration of the carbonated product, i.e., how close to

Colors, flavors, etc.

Ingredients

Main blending

with water

Sugars

Fruit

Citric acid

Heating

93 8C; 15s

Regeneration

Pasteurization

Cooling

Juice products

1000−3000 psi

Whole-fruit

products

Homogenization

Still

ready-to-drink

Filling line

Carbonates

Concentrates

(Quality control

check)

(Quality control

check)

Premix blending

fig00 02 Figure 2 Schematicrepresentationoftheproductionofsoftdrinks.SeeFigure3forindividualkeystages.

SOFT DRINKS/Production 5355

the maximum possible volume of carbon dioxide is

allowed to dissolve. An uncontrolled release of gas

from solution is known as fobbing. Partially saturated

solutions are more stable than saturated ones owing

to the additional pressure available over the equilib-

rium pressure. This additional pressure is known

as the overpressure and is used in the control of the

process. When the necessary degree of overpressure

may be maintained over a range of temperature and

carbonation, this is known as variable saturation. The

ready-to-drink, dilute product may be carbonated by

a reduction in temperature and injection of carbon

dioxide via one or more of the above techniques,

or the concentrated intermediate syrup may be

blended with a stream of carbonated water on line to

the filling apparatus, resulting in the correctly diluted,

carbonated, finished product in the pack.

Hygiene

0036 Throughout the production of all types of soft drinks

it is essential that plant hygiene is maintained at the

optimum level, whether chemical preservatives and/

or heat processing are used.

0037 Good manufacturing practice is a vital and integral

part of insuring minimal microbiological contamin-

ation of the product and will only be achieved if

attention is paid to certain areas of operation:

0038 Hygienic practices in receiving, handling, and pro-

cessing materials.

0039 Tight specifications for clean raw materials.

0040 Hygienic attitudes and understanding in all person-

nel.

0041 Hygienic design of plant and equipment.

0042 Hygienic operations of suppliers (especially of fruit

and carbohydrate materials).

Heat Processing

0043 An examination of the different types of processing

for concentrates, carbonates, and ready-to-drink soft

drinks is shown in Figure 3. This shows clearly that,

in addition to chemical preservation, blending,

carbonation, and basic hygiene and quality control

requirements, heat processing is a vital part of the

production of soft drinks.

0044 Although a manufacturer’s main protection against

microorganisms is the hygienic operation of the

manufacturing plant and that of suppliers, it may

still be necessary with certain microbiologically sensi-

tive formulations to enlist the help of both chemical

preservatives and heat processing. The use of heat

during the processing of soft drinks is covered in

outline here as it relates to the microbiological in-

tegrity of the product formulation. (See Preservation

of Food.)

0045Heat processing, or pasteurization, may be sub-

divided into four main categories for soft drinks

and/or material processing: (1) hot-fill; (2) in-pack

(or tunnel) pasteurization; (3) flash pasteurization:

(a) nonaseptic conditions or (b) aseptic conditions;

and (4) microfiltration. The selection of the required/

desired heat-processing conditions for any given soft

drink, intermediate syrup/blend, or raw material is

determined by a number of factors relating to the

following:

0046Presence of fruit materials and their origin, quality,

and microbiological status.

0047Presence of chemical preservatives – qualitative

and quantitative factors apply.

0048pH of the product.

0049Solids content and hence water activity.

0050Any other relevant processing conditions – holding

of syrup at ambient/raised temperature, use of

homogenization, filtration, etc.

0051Type of packaging to be employed.

0052Desired shelf-life.

0053Microbiological conditions (and history) of the

filling line and ancillary equipment to be employed.

(See Pasteurization: Principles.)

0054Hot-fill This can only be used for finished still

products or intermediate raw materials when being

packed for storage and shipment. The product/mater-

ial is heated in a heat exchanger to a temperature of

85–90



C; filled into the pack (glass, cans, etc.) so that

the temperature of the contents is in excess of 85



sealed via capping or seaming; inverted for a min-

imum of 1 min; and cooled as quickly as possible.

Any flaws in the capping/seaming will result in con-

taminated cooling water or air entering the package

and this will cause spoilage.

0055The disadvantage of this system is the large amount

of heat that is put into the product/material during

the whole process, which results in flavor, color, and

clouding degradation on storage, producing a reduc-

tion in total shelf-life on the product/material.

0056In-pack (or tunnel) pasteurization In its simplest

form, this type of pasteurization involves immersing

the filled, capped, or seamed pack of either still or

carbonated product in a tank filled with hot water at

60–90



C in a removable basket and holding at the

selected temperature for the required period of

pasteurization holding time. In reality the packs are

placed in water at a temperature lower than that

required and the temperature of the water is raised

until the specified temperature has been reached.

0057Examples of pasteurization conditions for this type

of processing are:

5356 SOFT DRINKS/Production