Module 7. Beverages

Lesson 26

CARBONATED BEVERAGES

26.1  Introduction

Carbonated beverages in the form on naturally occurring carbonated mineral water have been known to exist since long. Presence of carbon dioxide in aerated water and carbonated drinks enhance both palatability as well as appearance of these products. The origin of carbonated water is traced back to the work of Joseph Priestly who produced first man-made carbonated water in 1767. Carbonated drinks are invariably consumed without dilution and include crushes, lemonades, cola drinks and mixed drinks. Carbonated beverages are quite popular across the globe with an impressive dominance in world beverage market.

26.2  Ingredients Used in Preparation of Carbonated Beverage

26.2.1  Water

It is the main ingredient of carbonated beverage that comprises more than 90% of the total volume. The water which is used in preparation of carbonated beverages must of very high potable standards. Therefore, water pre-treatment is necessary to ensure the high standards of finished beverage such as removal of microscopic and colloidal particles by coagulation, filtration, softening and pH adjustment in the areas where water is of poor quality. Disinfection and chlorination remains the preferred method for the destruction of microorganisms. High level of nitrates in the water could be considered as possible risk for infants. It may also cause corrosion of tin plate and perforations of lacquer lining of cans. De-aeration of water is also required to facilitate subsequent carbonation and filling operations to minimize foaming problems.

Water used in carbonated beverage must possess following properties:

· Low alkalinity–to check neutralization of acids otherwise it would affect flavours and may decrease preservation effect of acids.

· Low iron and manganese – to prevent reaction with flavouring and coloring compounds

· No residual chlorine- as it affects flavour adversely and cause oxidation

· Very low turbidity and colour – to impart attractive appearance to the drink.

· Organic matters and inorganic solids must be very low – as it provides nuclei for CO₂ – resulting in beverage boiling and gushing at the time of filling or opening of bottles.

Water used in carbonated beverage manufacture must meet the following standards.

Particulars	Maximum Permissible Limit
Alkalinity	50 ppm
Total solids	50 ppm
Iron	0.1 ppm
Manganese	0.1 ppm
Turbidity	5 ppm
Colour	Colourless
Residual chlorine	None
Odour	Odourless
Taste	Tasteless
Organic Matter	No objectionable content

(Source: H. W. Houghton and D. MacDonald. 1978. Developments in soft Drink Technology. Vol. I, L/F/ Green (Ed.)Elsevier Applied Science Publishers, Barking)

*The water used for carbonated beverage production is often subjected to treatment to remove various impurities and make it suitable for production of soft drinks. The water treatment includes filtration, water softening, coagulation, chlorination, membrane filtration and ozonization. However, the sequence of pre-treatments depends on the quality of RAW water.

26.2.2  Sweetener

Sweetener serves three basic functions in carbonated beverages; impart sweetness, provide body and calorie. Sweetener used primarily in carbonated beverages is crystal sugar which must be of very high purity. It is used in the form of sugar syrup and final concentration of sugar varies between 8 to 14 percent in finished beverage. However, other sweeteners like glucose syrups, invert syrup, High fructose corn syrup (HFCS) etc. may also be used. Low calorie carbonated drinks invariably contain high intensity sweeteners or artificial sweeteners such as saccharin, aspartame, acesulfame-k and/or sucralose.

26.2.3  Carbon dioxide

Carbonated beverages contain carbon dioxide which “sparkle” the beverage and impart “fizziness”. CO₂ gas is inert, non-toxic, almost tasteless, easy to produce and impregnate in the liquid as compared to other gases. It is also available at relatively lower cost in liquefied form. It is soluble in liquids where its solubility increases when the temperature of liquid is decreased and it can exist as gas, liquid or solid. CO₂ produces carbonic acid when dissolved in water which in combination with other ingredients produces acidic and characteristic biting taste of carbonated water and beverages.

CO₂ may be obtained from carbonates, limestone, burning of organic compounds and industrial fermentation processes. CO₂ obtained by any process is purified to ensure that it is free from impurities and fit for human consumption. Purification of CO₂ is done by scrubbing with water to remove sulphurous compounds and passing through activated charcoal or carbon tower to remove odorous compounds. Many beverage manufacturers produce their own CO₂ on site by using packaged system.

26.2.4  Acids

Application of acids enhances the flavour and it also contributes towards the preservation of the beverage.  Wide varieties of acids are available for carbonated beverage manufacture, but citric, malic; fumaric, tartaric and phosphoric acid are most commonly used. Phosphoric acid is mainly used in cola type of beverages.

26.2.5  Flavouring and colouring ingredients

The flavouring component of the sugar syrup has the major influence on the flavour of the final product, used at very minor amounts i.e. 0.01 to 0.02 %. The nature of flavouring usually is determined by the type of the product. Fruit flavours are most commonly used, except in colas, which are flavoured by extract of cola root together with about 10% caffeine and a mixture of essences. Fruit flavour may be added in the form of juice, as comminuted (in the case of citrus fruit) or as an essence. Juice is normally used as a concentrate, citrus fruits; especially oranges are most widely applied. Citrus juice is debittered to avoid flavour defects. Essences may be prepared from artificial or natural sources. Artificial flavouring is not preferred because of doubtful safety. Natural citrus essences are composed largely of essential oils from the peel of the fruit. Hydrocarbons mostly limonene, constitute more than 90% of the oil, but contribute little or nothing, to flavour, acting primarily as a carrier.

Important colouring agents for carbonated beverages synthetic colours particularly certified coal tar colours. Caramel obtained from heated or burnt sugar is non – synthetic colour and are widely used in cola beverages. Permitted food dyes are generally preferred over natural fruit colours because of their greater colouring power and stability. Even when natural fruit extracts or juices are used their colours are generally supplemental with synthetic colours.

26.2.6  Emulsifiers, stabilizers and clouding agents

Emulsions may be used to impart cloudiness in the form of neutral emulsions and/or as flavouring agent as flavoured emulsions. The oil phase typically consists of a citrus essential oil containing an oil-soluble clouding agent, while the aqueous phase consists of a solution of gum arabic, or a suitable hydrocolloid of similar properties. An oil-in-water (O/W) emulsion is formed using a two stage homogenizer to yield droplets 1-2 µm in diameter for optimal stability and cloudiness. The clouding agent must contribute to opacity without affecting stability by producing creaming, ringing or separation and must also have no effect on colour, taste or odour. Brominated vegetable oil (BVO) was used as clouding agent for many years, however it is now been banned because of potential toxicity. Many alternatives have been attempted including sucrose esters, such as sucrose diacetate hexa-isobutyrate, rosin esters, protein clouds, benzoate esters of glycerol and propylene glycol, waxes and gum exudates. However, none of them have proved satisfactory. A soy protein based clouding agent has been found effective.

Stabilizers are used both to stabilize emulsions and also maintain the fruit components in dispersion. Besides they also improve mouthfeel and viscosity of the beverages. Most commonly used ones include guar gum, gum arabic, pectin, CMC and alginates.

26.2.7  Foaming agents

Presence of foam in headspace is considered desirable in certain carbonated soft drinks, such as ginger beer and colas. The most effective foaming agents are saponins which are extracted either from the bark of Quillaia or Yucca trees. The permitted level is up 200 ppm (in European Union) and 95 ppm in USA.

26.3  Manufacturing Process of Carbonated Beverages

Carbonated beverages are prepared following the steps as outlined in Figure 26.1.

Fig. 26.1 Process flow diagram for the manufacture of carbonated beverages

26.3.1  Syrup preparation

Syrup is usually prepared by mixing 1 part (volume) syrup to 3-6 parts (volume) water in stainless steel tanks fitted with top driven agitators. In sugar based product the syrup typically consists of sugar syrup of 67º Brix strength, citric acid, flavouring, colourings, preservatives and water. Sugar syrup is passed through a plate heat exchanger to decrease the microbial load. Syrup is pre-prepared, tested and diverted to proportioner for mixing with water and carbonation. Flow meters are most frequently used for proportioning. The syrup is dosed through a mass flow meter and the water dosing is done volumetrically by using a magnetic induction flow meter.

26.3.2  Carbonation and filling

Carbonation may be considered as the impregnation of a liquid with CO₂ gas. Earlier some the pre-syruping method was employed in which carbonated water and sugar syrup were metered separately into the bottle or other container. This method has been replaced in modern plants by pre-mix filling in which sugar syrup; water and CO₂ gas are combined in the correct ratio before transfer to the filler. The final beverage thus prepared before filling and regulation of carbonation and of the relative proportions of syrup and the water is of critical importance. The fundamental role of the carbonator is to obtain close contact between CO₂ gas and the liquid being carbonated. Factors determining the degree of carbonation are:

· Operating pressure in the system and temperature of the liquid

· Contact time between the liquid and CO₂

· Area of the interface between the liquid and CO₂

· The affinity of the liquid for CO₂ (affinity decrease as the sugar content increases);

· Presence of other gases.

Presence of air in syrup or water affects the carbonation process. Presence of air in beverage may also lead to mould growth and other oxidative reactions. Generally 1 volume of air exclude 50 volumes of CO₂.

Carbonation may be done in three different ways as follows:

I. Pre-syruping or syruping-filling process or post mix process: Containers are filled with flavoured syrup and now carbonated water is added in it to prepare carbonated drink.

II. Finished Product filling or Pre-mix: Flavoured syrup is added to water in correct proportion and then homogenous mix is carbonated to produce beverage.

III. Carbonation of water is done in the first stage, then flavoured syrup is metered and added into it to prepare carbonated beverage.

Degree of carbonation is judged by the amount of effervescence produced and it is most important characteristic of carbonated beverages. The optimum level of carbonation varies with the type of beverage. Higher level of carbonation in orange type of carbonated beverages and too low in cola or ginger ale is not liked by consumers. The level of carbonation varies between 1 to 4.5 volumes of CO₂ per litre of beverage; 1 volume for fruit based carbonated drinks, 2-3 volumes for colas and around 4.5 volumes for mixer drinks like tonic water, ginger ale. Use of polyethylene terephthalate (PET) bottles also requires slightly higher level of carbonation as some loss of CO₂ is bound to occur during storage.  Carbonated soft drinks are filled into either bottles or cans. Thick-walled, reusable, glass bottles were used for many years, but are being replaced by thin-walled, non-reusable glass and increasingly, PET bottles.

26.4  Carbonated Water

The consumption of carbonated water has increased rapidly. As per FSSA definitions carbonated water conforming to the standards prescribed for packaged drinking water under Food Safety and Standard act, 2006 impregnated with carbon dioxide under pressure and may contain any of the listed additives singly or in combination. Permitted additives include sweeteners (sugar, liquid glucose, dextrose monohydrate, invert sugar, fructose, Honey) fruits & vegetables extractive, permitted flavouring, colouring matter, preservatives, emulsifying and stabilizing agents, acidulants (citric acid, fumaric acid and sorbitol, tartaric acid, phosphoric acid, lactic acid, ascorbic acid, malic acid), edible gums, salts of sodium, calcium and magnesium, vitamins, caffeine not exceeding 145 ppm, ester gum not exceeding 100 ppm and quinine salts not exceeding 100 ppm. It may contain Sodium saccharin not exceeding 100 ppm or Acesulfame-k 300 ppm or Aspartame not exceeding 700 ppm or sucralose not exceeding 300 ppm.

26.5  Mineral Water

As per FSSA guidelines mineral water means all kinds o mineral water or natural mineral water by whatever name it is called or sold. All mineral waters shall conform to the following standards, namely:-

S. No.	Characteristics	Requirements
1	Colour, Hazen unit/True	Not more than 2
2	Odour	Agreeable
3	Taste	Agreeable
4	Turbidity (Turbidity unit, NTU)	Not more than 2 nephelometric
5	Total Dissolved Solids (TDS)	150-170 mg/Litre
6	pH	6.5-8.5

Besides these levels of mineral salts, heavy metals, toxic elements, environmental contaminants and microbial counts have also been specified.

26.6  Packaged Drinking Water (other than mineral water)

It can be defined as water derived from the surface water or underground water or sea water which is subjected to herein-under specified treatments, namely decantation, filtration, combination of filtration, aerations, filtration with membrane filter depth filter, cartridge filter, activated carbon filtration, de-mineralization, re-mineralization, reverse osmosis and packed after disinfecting the water to a level that shall not lead any harmful contamination in the drinking water by means of chemical agents or physical methods to reduce the number of micro-organisms to level beyond scientifically accepted level for foods safety or its susceptibility. The standards, packaging and labelling requirements have also been specified under FSSA rules.