Module 7. Beverages

Lesson 25

ADDITIVES FOR FRUIT BASED BEVERAGES

25.1  Definition and Function of Food Additives

A food additive is a substance which is added to food and is involved in its production, processing, packing and/or storage without being a major ingredient. The food additives are functional chemicals that are used at very low level (from ppm level to few percentages) and their usage is regulated by the laws. The major function which is performed by the food additives are as follows:

25.1.1  Improve nutritive value of food

Additives such as vitamins, minerals, amino acids derivatives are utilized to increase the nutritive value of food. Certain additives like soluble dietary fibers, low calorie sweeteners, bioactive components are newer entrants in the list of nutritive food additives.

25.1.2  Enhancement of sensory quality of food

Colors, odour, taste and consistency or texture are important for the acceptability of any food product as they are perceived by senses. These sensory attributes are affected by the level of ingredients and processing methodology adopted. Storage temperature and packaging atmosphere also determine the quality of processed foods. Any adverse effect can be corrected or readjusted by additives such as colourings, aroma compounds or flavour enhancers. Development of ‘off-flavour’ for instance that derived from fat or oil oxidation can be prevented by using antioxidants. Likewise viscosity and suspension stability of beverages could be improved or maintained by careful addition of hydrocolloids.

25.1.3  Prolongation of shelf life of food

The extension of shelf life involves protection against microbial spoilage, for example by using additives that inhibit the growth of microbes, and use of active agents which suppress and retard undesired chemical and physical changes in foods, is the another objective of food processing.

25.1.4  Processing aids

Certain additives are added to facilitate various processing operations during beverage manufacture. These include enzymes, emulsifiers, stabilizer and anti-caking agents. Enzymes are invariably used for the extraction as well as clarification of fruit juices. Emulsifiers are required for the formation of stable flavour emulsion mainly in lemonades.

These additives are diverse in nature and derived from wide range of sources, which are listed below (Table 25.1).

Table 25.1 Nature and sources of food additives

S. No.

Nature

Sources

1.

Inorganic Chemicals

Salt, Sulphites, phosphates etc.

2.

Synthetic Chemicals

Dye, Silicones, Vitamin A, Benzoates etc.

3.

Extraction Products

Gums, Essential oils, tocopherols etc.

4.

Fermentation Products

Enzymes, Acid and Yeast etc.

25.2  Beverage Additives

There is great diversity in beverages and accordingly a wide range of ingredients are required in their formulations. There are certain additives like sugar or sweeteners (except in low calorie beverages) which are added in higher amounts whereas additives like preservatives are added in minute quantity. Hence according to the amount the additives may be grouped as Major and Minor additives.

25.2.1  Major additives

Apart from fruit juice, sugar and acid constitutes the major percentage of the beverage formulation, hence these two belongs to the category of major beverage additives:

25.2.1.1  Sugar

Sugars are added primarily as flavouring additive to impart the sweetness in the beverages. Conventionally sugar performs number of basic functions in beverages.

·      They improve the palatability of certain bland and insipid tasting fruits & vegetables

·      They provide bulk and body to beverages thus enhance mouthfeel

·      They modify the freezing point and control viscosity

·      They also act as mild preservative, modify the osmotic pressure and check spoilage

Sweeteners may be classified in a variety of ways: nutritive or nonnutritive, natural or synthetic, regular or low-calorie/dietetic.

1.     Natural or Synthetic Sweeteners

The sweeteners derived from the food sources are termed as natural. Example: Crystal sugar obtained from cane sugar or beet root, glucose syrups manufactures from maize starch, honey etc. The sweeteners which are manufactured by chemical synthetic processes are termed as synthetic sweeteners. Example includes high intensity sweeteners like saccharin, aspartame, acesulfame-K etc.

2.     Nutritive or Non-Nutritive Sweeteners

Certain sweeteners are metabolized in body and generate energy, hence are termed as nutritive and caloric sweeteners. Nutritive sweeteners also cause dental carries. Sweeteners that are metabolized but do not contribute towards the energy significantly are called as non-nutritive or non-caloric sweeteners. Traditional sweeteners fall into the category of nutritive whereas synthetic ones belong to non-nutritive sweeteners.

3.     Regular or High-intensity Sweeteners

The classification of sugars on the basis of quantity required to give equivalence sweetness give rise to two categories i.e. regular or high-intensity. High-intensity sweeteners required much less amount for yielding the similar sweetness intensity. All low calorie sweeteners are considered as high-intensity sweeteners. The relative sweetness of various sugars is listed below (Table 25.2).

Table 25.2 Relative sweetness of various sweeteners

Sweeteners

Sweetness Relative to sucrose

Sugar (Sucrose)

1

High-fructose corn syrup

1-1.5

Fructose

1.2-1.7

Invert sugar

1.3

Glucose

0.75

Sorbitol

0.5-0.7

Mannitol

0.7

Xylose

0.4

Maltose

0.32

Galactose

0.32

Raffinose

0.23

Lactose

0.16

Saccharin

300

Cyclamate

30

Aspartame

200

Acesulfame K

200

 

25.2.1.1.1  Various classes of sugars

a)     Sucrose

Manufactured from cane sugar or beetroot and may be added either in dry form or as syrup (65-70% strength) in beverage manufacture. Sucrose is available in various particle size and colour grades which depend on the degree of refining. In beverage manufacture normally the cane sugar obtained by carbon-refining process is preferred as it does not cause blackening of content. In cola type or malt beverages brown sugar may also be used.

b)    Glucose Syrup

On industrial scale corn starch is hydrolyzed by using acid or enzymes to produce corn syrup and these syrups are available in different Dextrose Equivalent (DE) values. The term DE value refers to the percentage of dextrose in the mixture of carbohydrate produced on hydrolysis. DE value also indicates the sweetness and viscosity of the syrup. High DE value reflects more sweetness and less viscous syrup. Typically glucose syrups having DE value 42-65 are used in beverage manufacture. Glucose syrups are used in energy drink, where a carbohydrate that yields quick energy is desired. The advantage of using glucose syrups is higher level of solids as compared to sucrose syrup. However, higher viscosity of glucose syrup at low temperature (below 30oC) create problem in mechanical operations.

c)     High Fructose Corn Syrup

High fructose corn syrup (HFCS) is manufactured by first hydrolyzing the corn starch to dextrose then enzymatically converting dextrose into fructose. HFCS contain around 42% fructose plus 51% dextrose and have sweetness equal to sucrose. HFCS is mainly used in USA and to a lesser extent in Europe. These syrups are also liable for browning.

d)    Invert Sugar Syrup

Invert sugar syrup is produced by acid or enzymic hydrolysis of the sucrose into its constituents sugars i.e. glucose and fructose. Invert sugar usually contains a mixture of sucrose, dextrose and fructose. The major benefits of using invert sugar are an increase in osmo-molality and decreased tendency of crystallization.  The application of invert sugar is also restricted to cola type of beverages where brown colour is desired.

e)     Saccharin

Saccharin has been used as a food additive since the early 1900s and is the most widely used non-nutritive sweetener worldwide. Saccharin occurs as white, crystals or a white crystalline powder, is odorless, or has a faint aromatic odor. It is slightly soluble in water, sparingly soluble in alcohol and soluble at 0.05% in a fixed oil. It is about 300 times as sweet as sucrose. In its bulk form, saccharin and its salts have been shown to be stable for several years. In aqueous solutions, saccharin demonstrates high stability over a wide pH range. It is commercially available in three forms: acid saccharin, sodium saccharin, and calcium saccharin. Sodium saccharin is the most commonly used form because of its high solubility and stability. Due to its bitter aftertaste and health implications, saccharin has limited potential. It had been linked with occurrence of bladder cancer in rodents, however later investigations in higher animals did not confirm the relation between bladder cancer and saccharin consumption.

f)      Acesulfame K

Acesulfame K has a rapidly perceptible sweet taste 200 times as potent as sucrose. Acesulfame potassium occurs as a colorless to white-colored, odorless crystalline powder with an intensely sweet taste. It dissolves readily in water, even at room temperature, and is very stable, with virtually no change in concentration observed in the pH range common for foods and beverages after several months. It is being used in dry beverage bases. Beverages containing acesulfame K can be pasteurized under normal pasteurization conditions without loss of sweetness. It blends well with other sweeteners and is especially synergistic with aspartame and sodium cyclamate. It is non-caloric and has a taste closer to sucrose when combined with other non-caloric sweeteners. It is not considered to be carcinogenic and mutagenic. The adequate daily intake (ADI) of acesulfame-k is 15 mg/kg body weight/day of an adult.

g)     Aspartame

Aspartame was approved in 1981 for use in dry beverages mixes and later on 1983, in liquid soft drinks in USA. However, in India application of these artificial sweeteners was permitted in certain food stuffs including beverages.  Aspartame occurs as off-white, almost odorless crystalline powder with an intensely sweet taste. The approximate sweetening power is 200 times that of sucrose. It is slightly soluble in water and sparingly soluble in alcohol. The ADI of aspartame is 50 mg/kg body weight/day. The use of aspartame has been of some concern due to the formation of the potentially toxic metabolites, methanol, aspartic acid and phenylalanine. Despite it, aspartame is the most successful high intensity sweetener currently used. Its role as a food ingredient that enhances fruit flavours makes it suitable for soft drinks and yoghurt. Two major disadvantages of aspartame are its instability in acidic conditions and its loss of sweetness during prolonged heating.

h)    Cyclamates

Cyclamates were discovered in the mid-1950s. It is 30 times sweeter than sucrose and has been particularly useful in fruit products. In 1969, it was banned because of some carcinogenic effect by FDA.

i)       Sucralose

Sucralose occurs as anhydrous, white, crystalline, orthorhombic needle-like crystals with an intensely sweet taste. It is a chlorinated sucrose derivative that is 500 to 600 times sweeter than sucrose. It has no calories and is exceptionally stable. The ADI is 5 mg/kg body weight/day. Sucralose is not metabolized in the body and does not break down as it passes rapidly through the body. The sweetest of the currently approved sweeteners, it has a clean, quickly perceptible sweet taste. Still the safety of sucralose is not fully conclusive.

Besides these there are other low calorie and high-intensity sweeteners which need permission from regulatory authorities. These include alitame, neotame, stevia, nehesperidin dihydrochalcone and glycyrrhizin. 

j)      Sugar substitutes

Sugar substitutes are those compounds that are used like sugars for sweetening, but are metabolized without influencing of insulin and producing much calorie. Polyols (sugar alcohols or polyalcohol) are chemically reduced carbohydrates. These compounds are important sugar substitutes because polyols are absorbed more slowly from digestive tract than is sucrose. Sorbitol, Mannitol, Xylitol etc are being used in food application.

25.2.1.1.2  Acidulants

Acidulant are acids that either occur naturally in fruits and vegetables or are used as additives in beverage formulation.  Mainly, citric acid, adipic acid, fumaric acid, tartaric acid, phosphoric acid, lactic acid malic acid  and acetic acid are used to play different roles in different beverages. Acidulants functions includes

·   Provide sourness to product

·   Enhance palatability by balancing the sugar to acid ratio

·   Enhance flavours

·   Act as thirst quenching by increasing flow of saliva

·   Act as buffer to control acidity level

·   Act as a mild preservative by regulating pH

a)     Citric acid

Citric acid is the most versatile and widely used food acidulant. It is useful characteristics include excellent solubility, extremely low toxicity, chelating ability and pleasantly sour taste. FDA classifies citric acid and its sodium and potassium salts as GRAS food additives when used in accordance with the good manufacturing practices. Citric acid is produced commercially by mold fermentation of sugar solutions (most commonly, dextrose and beet molasses) using strains of Aspergillus niger. Beverages are the major food use for citric acid, accounting for an estimated 65% of citric acid’s total food acidulant consumption. Citric acid and its sodium salt are used extensively in carbonated beverages as a buffer to regulate tartness if the acid level is high. It is also used as flavor enhancers and preservative.

b)    Malic acid

Malic acid is prepared by hydrolyzing maleic anhydride to malic acid and, at elevated temperature and pressures, forming an equilibrium mixture of malic acid, fumaric acid, and malic acid. Malic acid is used in a variety of products, but mostly in fruit-flavoured sodas such as those with apple and berry flavor. Malic acid is preferred acidulant in low-calorie drinks, and in cider and apple drinks, it enhances flavor and stabilizes the color of carbonated and noncarbonated fruit flavoured drinks and cream sodas. In sugar-free drinks, malic acid masks the off-taste produced by sugar substitutes.

c)     Tartaric acid

Tartaric acid has a strong, tart taste and augments natural and synthetic fruit flavours, especially grape and cranberry. It is utilized in fruit juices and drinks. High prices and limited availability inhibit tartaric acid from widespread use as a food acidulant.

d)    Phosphoric acid

Phosphoric acid and its salts account for 25% of all the acids used in the food industries. Phosphoric acid has a characteristic flavor and tartness and is used almost entirely in cola flavored carbonated beverages. A small quantity is also used in some root beer brands. It is least costly of all the food-grade acidulant; it is also the strongest, giving the lowest attainable pH.   

e)     Fumaric acid

Fumaric acid is principally used in fruit juices and gelatin desserts and wines. Fumaric acid competes with other acidulants such as citric acid, tartaric acid, and malic acid. Although it is less costly than some alternatives, its relatively strong acid taste and low solubility make it less appropriate for certain food uses. Its limited solubility coupled with an extremely low rate of moisture absorption makes fumaric acid a valuable ingredient for extending the shelf life of powdered dry mixes.

There are certain other acidulants like ascorbic acid, adipic acid, acetic and lactic acid that may also be used in beverage formulation mostly in combination with major acids. Ascorbic acid also acts as antioxidant.

25.2.2  Flavourings

Flavors are concentrated preparations used to impart a specific aroma to food or beverages. Flavors may be added to food products for the following reasons:

·       To create a totally new taste

·       To enhance, extend, round out or increase the potency of flavours already present

·       To supplement other more expensive flavors or replace unavailable flavors

·       To mask less desirable flavors- to cover  harsh or undesirable tastes naturally present in some food

·       Stimulation of flavour perception of expensive flavours

Flavouring is most critical operation in food processing as acceptability of any products largely governed by the flavour perception by consumers. Various food processing operations often lead to loss of flavouring chemical either due to volatilization or because of conversion of flavouring compounds into off-flavouring compounds. However, flavour of beverage must be identical to the fruit which is used as base material. Fruit aroma consists of few hundreds to thousand compounds for example orange flavour  contain more than 200 compounds ranging from simple phenolic to complex terpenoids, esters etc. Therefore, mimicking of fruit flavour in beverages is quite complex task and requires great expertise. Various compounds used for flavouring purpose may be categorized into three groups.

25.2.2.1  Natural flavours

Natural flavours include extracts from natural sources in the form of essential oils, oleoresins, essence or extractive, distillate or any product formed during normal processing such as roasting, heating etc. Example of natural flavour is extracts of vanilla roots, roasted coffee beans, herbs etc. Practically natural flavours are essential oils, oleoresins, and true fruit extracts. A special type of natural flavour is fruit flavour concentrate. Fruit flavour concentrate is prepared by removing the water under vacuum and added back aroma back into the concentrate. The most common fruit flavour concentrate include apple, berry, grape and citrus fruits.

25.2.2.2  Nature identical flavours

These can be defined as flavouring substances that are synthesized or isolated by chemical processes. These compounds are chemically and oragnoleptically identical to the naturally occurring substance. They do not contain any artificial substances. Example of nature identical flavouring include ethyl vanillin for vanilla, benzaldehyde for bitter almond, isoamyl acetate for banana,  limonene for orange, methyl anthranilate for grape etc.

25.2.2.3  Synthetic flavours

Term synthetic flavour is used for those substances which are not identified in naturally occurring products intended for human consumption. They are produced by fractional distillation process and additionally chemical modification of naturally sourced chemicals, coal tar or crude oil. Although, they are chemically different from natural compounds but identical in flavour perception. These are essence and produced by various processes or by mixing various compound specified in the aroma of any fruit. Example: esters give the characteristics fruity aroma and γ-undecalactone is included in peach flavour formulation.

25.2.3  Colourings

Colours are used in processed foods to improve the appearance and thus also influence the perception of texture and taste. The colours are permitted additives in beverage to provide different shades and improve the aesthetic quality of beverages. Food colours are added in beverages because of the following reasons:-

·      To give attractive appearance to foods that would otherwise look unattractive or unappealing

·      For product identification as majority of fruit beverages are characterized by the colour of fruit which is used in its formulation

·      To ensure uniformity of the colour due to natural variations in colour intensity because of variation in harvesting period, variety etc.

·      Intensification of the colour naturally occurring in fruits & vegetables

·      Colours also serve as mean of quality assurance during the production, transportation and storage.

Various compounds which are used for colouring purpose may be divided into three groups; natural colours, nature identical colours and synthetic colours or dyes.

25.2.3.1  Natural colours

These colours are derived from the natural sources and are exempted from the mandatory certifications by the regulatory authorities. These are attractive alternatives to artificial colourings and being of natural origin these are preferred by consumers as well. Some of the natural colourants are listed in Table25.3.

Table 25.3 Natural colourants used in fruit based beverages

Compounds

Source

Colour Impart

Paprika

Capsicum anum

Red colour

Anthocyanin (cyaniding, petunidin, betacyanin)

Beet root, Pomegranate, grape skin

Blue, Purple and pink

Bixin (Annato extract)

Bixa orellana

Yellow colour

Cochineal

Coccus cacti

Orange to Red

Curcumin

Curcuma longa

Orange yellow

Crocin & Crocetin

Crocus sativus

Yellowish red

Caramel

Heated sugar solution

Chocolate Brown

 

However, the poor stability of natural colourant is major obstacle in their wider application in beverage formulation. The extraction of these colouring pigments at cost-effective manner is still a major challenge in usage of natural colours.

25.2.3.2  Nature identical colours

These compounds are similar chemically to naturally occurring compounds but are extracted using solvents. These are relatively more stable than natural counterparts. These include β-carotene, apocarotenal ( β-apo-8,- carotenal) which produce yellow to orange hue, canthaxanthin that impart red colour and riboflavin which give greenish yellow to yellow colour. The stability of these colourants is a major problem. Mostly these are available in oil-soluble forms.

25.2.3.3  Synthetic colours

These are certified food colours which may be divided into dyes and lakes. These dyes are water soluble and relatively stable under wide range of pH, processing temperature and storage. Lakes are generally not used in beverage formulations. These dyes are popularly called as coal tar dyes. Azo dyes are brighter in colour and of high tinctorial strength. Initially there were 11 permitted synthetic dyes but now three of them have been omitted due to safety concerns. The permitted dyes are carmosine (Red), Ponceau 4R (Red), Sunset yellow FCF (Red), Tartrazine (Lemon yellow), Brilliant blue FCF (Green blue), Erythrosine (Pink to Blue), Indigo carmine (Deep blue), Fast green FCF (Turquoise). The three dyes which have been removed from the list are Amaranth, Fast Red E and Green S. The dyes have fastness properties with alkali, acid, light and additives. They can withstand processing temperature of up to 110oC. The maximum permissible limit of these dyes is 100 ppm as higher concentration may cause cancer.

25.2.4  Hydrocolloids

 These consists a group of substances all of colloidal dimensions, having great affinity for water and hence called as hydrocolloids. These hydrocolloids perform a number of functions in fruit juices and beverages:

·   Prevent gravitational suspension or sedimentation of suspended particles in beverage

·   Improve the viscosity of juices and beverage

·   Act as clouding agent in products like nectar, lemonades, where cloud formation is a desirable attributes

·   Act as clarifying agent in certain beverages like guar gum, alginates, gelatin, They cause flocculation of impurities

·   Assist in encapsulation of additives in powdered mixes

·   Prevent crystallization in high sugar containing beverages

These hydrocolloids may be classified into several categories as mentioned below.

·   Source (natural/natural identical/synthetic)

·   Chemical nature (polysaccharides/protein)

·   Ionization (Ionic/non-ionic/neutral)

·   Gelling behaviour (Gelling/thickening/stabilizing)

25.2.4.1  Carboxymethylcellulose (CMC)

It is the primary cellulose ester compound in food and beverages applications. CMC is used at approximately 0.5% to thicken fruit juices and to prevent floating or settling of fruit, as well as impart a clearer, brighter appearance, produce a desirable gel texture, and reduce syneresis. 

25.2.4.2  Alginates

It includes various salts of aliginic acid and propylene glycol alginate (PGA). Alginate is extracted from a brown algae Macrocystis pyrifera. PGA is used at 0.1-0.2% concentration to suspend pulp in fruit drinks. The major application of sodium alginate is in dairy beverages.

25.2.4.3  Guar gum

Guar gum is extracted from the pods of leguminous plants. India is the largest producer and exporter of guar gum. It is water soluble and produces very high viscosity even at low concentration. It is available in different particle size and also hydrolyzed for certain specialized applications. It is used as a thickening and viscosity control agent in fruit nectars.

25.2.4.4  Gum arabic

Gum arabic is water-soluble natural gum which is obtained as exudates form the trees of Acacia senegal. It is also known as gum acacia.  The solutions of gum acacia are of low viscosity. It is mainly used as an emulsifier in beverages for stabilization of fruit flavors especially in citrus beverages. In powdered beverage mixes it is used to encapsulating flavours.

25.2.4.5  Pectin

Pectin is a hydrocolloid obtained commercially from the citrus peel or apple pomace. It consists of α-galacturonic acid molecules which are linked through α-glycosidic linkages and the side chain of pectin molecule is esterified. Pectin is mainly used for gelling purpose but nowadays it is gaining popularity as beverage stabilizers. Major application of pectin (High methoxyl) is in stabilization of acidified dairy drinks. Besides it the major application of pectin is in preparation of gelled products such as jam, jelly and  marmalade.

25.2.4.6  Gelatin

Gelatin is obtained from the collagen or connective tissue of meat animals. It is used extensively for clarification or fining of cider, fruit juices, and wine. Amount of gelatin used is in the range of 50-300 g per 1000 liter juice to be treated. As per legal requirements in India, use of gelatin in fruit based products shall be labeled with non-vegetarian symbol on the pack.

25.2.5  Preservatives

A chemical preservative may be defined as any additive substance that tends to prevent or retard deterioration when added to foods. It may prevent or retard changes in odour, flavor, nutritive value, or appearance. They inhibit the contamination of foods by microorganisms such as yeasts, bacteria, molds or fungi. The principal mechanisms are reduced water availability and increased acidity. Only sorbates, benzoates, propionates and sulfites are used broadly in fruit processing. The principal mechanisms are reduced water availability, change in redox-potential and increased acidity. Many of these preservatives target microbial membranes and affect the permeability of it, thus the viability of microbe. Preservatives may be classified as Class I & Class II preservatives. Class I preservative includes additives from natural sources which also exhibit preservative effects in foods. Example of Class I preservatives are salt, sugar, vinegar, spices, honey, edible oils etc. Class II preservatives are chemically derived compounds. Only sorbates, benzoates, propionates and sulfites are used broadly in fruit processing.  I n case of Class I preservatives level of addition is regulated by Good Manufacturing Practices (GMP), while in Class II preservatives it is fixed by regulatory agencies on the basis of safety and toxicity evaluation.

25.2.5.1  Benzoic acid

Benzoic acid and sodium benzoate is permitted to the maximum level of 0.1%.  Benzoic acid and its sodium salt are most suitable for preserving foods and beverages that naturally are in a pH range 2.5 – 4.0.  The narrow pH of its activity limits wider application of this preservative in foods.  Benzoic acid and sodium benzoate are used to preserve carbonated @ 0.03-0.05% and non-carbonated beverages @ 0.1%, fruit pulps and juices, jams and jellies, salad dressings, sauces and ketchups. Sodium benzoate is more effective against yeasts and bacteria than molds.  The antimicrobial activity varies with foods, its pH and water activity and with types and species of microorganisms.  Pathogenic bacteria may be inhibited by concentrations of 0.01- 0.02% undissociated benzoic acid.  As an antimicrobial agent, benzoate acts synergistically with sodium chloride, sucrose, heat, carbon dioxide, and sulphur dioxide.

25.2.5.2  Sorbic acid

Sorbic acid is widely used food preservatives in the world.    Sorbates exhibit inhibitory activity against a wide spectrum of yeasts, molds and bacteria including most food borne pathogens. They can be used to suppress yeasts during lactic fermentation.  The inhibitory activity of sorbates is attributed to the undissociated acid molecule and hence is pH dependent.  The upper limit for its activity is at about pH 6.5 in most applications, and the activity increases with decreasing pH. Potassium sorbate is used where high solubility is desired. Sorbates are frequently used in dried fruits, fruit salads, carbonated and noncarbonated beverages. Usage rates of sorbates in fruits are low, being 0.025-0.075% in fruit drinks and 0.1% in beverage syrups.

25.2.5.3  Salts of sulphite, bisulphite and metabisulphite

Salts of sulphite, bisulphite and metabisulphite is decomposed by weak acids such as citric, tartaric, malic and carbolic acids to form potassium salt and sulphur dioxide, which is liberated from potassium sulphurous acid with water, when added to the fruit juice or squash.  Free sulphurous acid is more effective (120 times) than combined sulphurous acid.  The undissociated sulphurous acid molecule prevents the multiplication of yeasts, while the sulphurous acid ion inhibits the growth of bacteria.  Glucose, aldehydes, ketones, pectin and breakdown products of pectin, etc., which are found in fruit juices, combines with sulphur dioxide reducing the effectiveness of sulphur dioxide.   Being more effective against molds than yeasts, sulphur dioxide has found wide use in the fermentation industries.  It cannot be used in the case of some of the naturally coloured juices like phalsa, jamun, pomegranate, strawberry pulp, etc. on account of its bleaching action on anthocyanin.  It cannot also be used in products, which are to be packed in tin container, because it not only acts on tin container causing pinholes, but also forms hydrogen sulphide, which has an unpleasant smell and also forms a black compound with the iron on the base plate of the tin container.

25.2.6  Nutritive additives

25.2.6.1  Vitamins

Beverages are enriched with vitamins to adjust for processing losses or to increase the nutritive value. Such enrichment is essential for fruit juices canned vegetables, and other beverages. Vitamin C (ascorbic acid) is the most commercially important vitamin used as a food additive in terms of volume. The most important applications for vitamin C include fruit juices, fruit flavoured drinks, juice-added sodas, and dry cocktail or beverages powder mixes. As an antioxidant, this vitamin is frequently added to fruit juice to preserve and protect against color change of fruit ingredients.

25.2.6.2  Minerals

Beverages are usually an abundant source of minerals as they contain fruits, but due to dilution the relative intake of minerals is quite less. Normally the electrolytes i.e. sodium, potassium and chlorides are added in energy drinks and other soft drinks. Nowadays, beverages are also considered an important vehicle for mineral fortification. The minerals normally used for fortification are calcium, iron, zinc and magnesium.