This Bottle may be fairly called the greatest invention of the age in connection with Aerated Waters, as it combines all those qualities so long sought for in a Soda Water Bottle; and we challenge any one, however biased his opinion, to name one fault.
A Sam-pie will be sent, filled with Aerated Water, and packed, in case, for Is. 6d., prepaid.
Figure 5.1 Effective in retaining carbon dioxide, the Codd's bottle was widely acclaimed, but the drink components it contained proved, at times, cause for concern.
About this time, the screw (vulcanite)-stoppered bottle and the swing (ceramic) stopper, operated by a wire spring, were also in widespread use. Then towards the end of the nineteenth century there appeared an entirely new closure concept, the crown cork first devised in Baltimore in 1889 and then later awarded a patent in the United Kingdom during April 1892. This closure consisted of a thin metal disc crimped at the edges and originally lined with cork which was clamped around the bottle opening using external mechanical force. This closure is still in use today, although the cork liner has now been replaced with a soft plastic coating. When introduced the crown cork had the advantages of both saving cost and, because of its one-off usage, being more hygienic than other types of closure.
The preoccupation with aerated waters was, of course, due to the stabilising effect of the dissolved carbon dioxide gas, the first additive of major importance. While developments were taking place around the filling and containerising of the new drinks, there were other changes in formulation that would relate further to the term 'additive'.
Flavourings, colourings, acidulants and new preservatives were tried, at times with disastrous results. There is ample evidence that with lack of statutory controls in the early stages some of the bottled products would have been lethal to the consumer. An early edition of Skuse's Complete Confectioner, published around 1890, contained information on cordials and other beverages, in a section on flavours and colours it seriously warned against the use of chrome yellow (lead chromate) as it had been known for certain confectioners to use a little chrome yellow to create stripes in sweets. Much of the hazard was created by the presence of impurities in some of the materials used in the manufacture of certain additives. Frequently, the sulphuric acid or vitriol used in the generation of carbon dioxide from whiting, or more effectively from bicarbonate of soda, was contaminated with metallic impurities, including arsenic and nitrogen compounds, and care had to be exercised to select the best grades.
A recurring problem, again centred on impurities, was the risk of contamination due to lead and copper coming into contact with materials used in the preparation of soft drinks. The Mineral Waters Trade Review and Guardian (January issue, 1875) dwells on the subject at some length, and a particular case is cited where lemon oils imported from Messina, Italy, were found to be heavily contaminated with lead following a period of storage in copper cans. The contact surfaces had been 'tinned' and it was established that the solder used for the purpose contained relatively high levels of lead.
Today the limits on impurities are well defined in legislation. Under European regulations non-alcoholic beverages for consumption without dilution are given maximum limits for lead (0.2 mg/kg), arsenic (0.1 mg/kg), copper (2 mg/kg) and zinc (5 mg/kg). In terms of food and drink additives, custom and use eventually indicated what dosage levels were acceptable, but there was no rigid system of assessment for these. In England, the Mineral Water and Food and Drugs Acts entered the statute books in 1875. These instruments indicated very clearly, but nevertheless with some generality, what the industry should not do but omitted to indicate what might be done without fear of the consequences. For instance, Section 3 of the Act (38 & 39 Vic.c.63) of 1875 stated that 'No person shall mix colour, stain, or powder ... any article of food, with any ingredient or material so as to render the article injurious to health with the intent that the same may be sold in that state.' There was no restriction of colouring material of any kind other than that nothing 'injurious to health' could be used.
The absence of standards of quality or composition, apart from those relating to pharmaceutical products (the reference here was the British Pharmacopoeia), caused some confusion in the early years. Toxicology was in its infancy as a science and many of the ingredients used in the manufacture of beverages to stabilise and standardise the drink with apparent safety were subsequently found to be injurious to health at the levels used. It has been said that in the area of food and drink everything is a poison, it just depends on the dosage or intake!
The process of assessment and control has continued to the present day, such that, by and large, all food ingredients are controlled by legislation. When and where appropriate these are removed from the permitted list or limited to an acceptable daily intake (ADI).
Across the globe, countries employ their own legislative controls for food ingredients, but there are two main regions that exert great influence upon world opinion on this issue: the European system controlled by the European Parliament with designated E-numbers for permitted food additives, and the system used in the United States where at the federal level the Federal Food, Drug and Cosmetic Act (FFDCA) lays down the framework for food safety.
The term 'soft drink' applies to beverages containing flavourings and/or fruit juices together with other constituents of technological or nutritional value designed to enhance the appearance and stability of the product and to ensure its organoleptic properties remain intact during a reasonable shelf life. These factors are taken into consideration in all development work, and in order to meet current stringent quality and legislative controls a new beverage is subjected to extensive trials to assess the suitability and performance of all components in its makeup. It becomes essential to arrive at the correct ingredient formulation to achieve a reproducible product.
Table 5.1 lists the functional constituents of soft drinks and their typical usage levels. Each category of ingredient, other than fruit juices and carbohydrate/intense sweeteners, is discussed in more detail in the following sections.
Water, as the main component of a soft drink, usually accounts for between 85 and 95% of the product and acts as a carrier for the other ingredients. Its quality must conform to rigid requirements and not interfere with the taste, appearance, carbonation or other properties of the drink. Subject to the location of the bottling plant, the source of water and product specifications, it may be necessary to carry out treatment to improve the quality of the water used in the manufacture of soft drinks.
In most urbanised areas of the world, public water supplies can meet consumer requirements of potability, but for the soft drinks manufacturer this is not always a suitable qualification for use of the water as a raw material. Most soft drinks factories will carry out their own treatments to counteract the likelihood of a possible change in quality. This is most important in areas where variations are introduced as a result of the use of a national grid system for water supply.
In less developed countries, water treatment becomes an essential prerequisite where microbial loading could provide cause for concern. It is necessary for a full water treatment to be effective and to ensure the wholesomeness of water supplies for boiling purposes.
Water should comply with the following quality requirements. It should be free from
• high levels of elements and mineral salts;
• objectionable tastes and odours;
• organic material.
It should also be
• clear and colourless;
• free from dissolved oxygen;
• sterile, that is, free from micro-organisms.
Ideally, a non-variable supply of water should be available at all seasons of the year to allow a standard manufacturing process to be established.
96 CHEMISTRY AND TECHNOLOGY OF SOFT DRINKS AND FRUIT JUICES Table 5.1 Soft drink components, general usage and contribution
Component Typical use level
Water (quality must meet rigid Up to 98% v/v when high-intensity sweeteners requirements) in use
Bland carrier for other ingredients. Provides essential hydration effects to enable body metabolism.
Sugars 7-12 % m/v when sole source of sweetener
Contribute sweetness, body to drink. Act as synergist and give balance to flavour
Fruit juice Widely variable usage. Usually up to 10% as natural strength, although some specialised lines in this Provides fruit source identity, flavour, mouthfeel effects. Also contributes to sweetness and acidity.
High-intensity sweeteners Use based upon sucrose equivalence (e.g. aspartame might be employed at 0.40-6% m/v as sole sweetener)
Provide sweetness, calorific reduction. Synergist action. Often used in combination e.g. aspartame with acesulfame K
Carbon dioxide 0.30-6% m/v
Provides mouthfeel and sparkle to drink (carbonates only)
Contributes sharpness, sourness, background to flavour. Increases thirst-quenching effects
Flavours Nature-identical and artificial: 0.10-28% m/m
Natural: up to 0.5% m/m Provide flavour, character and identity to the drink Emulsion (flavour, colour, cloud etc.) 0.1% m/v
Carrier for oil-based flavours or colours. Gives cloudy effect in drink to replace or enhance cloud from natural juices
Colours (natural or synthetic) 0-70 ppm
Standardise and identify colour tone of drink
Preservatives Statutory limits apply (e.g. sorbic acid up to 250 ppm in EU)
Restrict microbial attack and prevent destabilisation of the drink
Antioxidants (e.g. BHA, ascorbic acid) Less than 100 ppm, subject to user-country legislation Prevent oxidation, limit flavour and colour deterioration
Quillaia extract (saponins) Up to 200 mg/l (EU), up to 95 mg/l (USA)
Acts to provide heading foam, mainly of use in carbonates
Hydrocolloids (mucilaginous gums) 0.1-0.2% per GMP, minimum amount required to create desired effect
Carrageenans, alginates, polysaccharides, carboxy methyl cellulose etc. Provide mouthfeel, shelf-life stability, viscosity
Vitamins/Minerals ADI applies
Used in 'healthy-living' drinks to provide nutritional requirements
The quality of fresh water supplies will be dependent upon the geology of the catchment areas. All fresh water is derived from rainfall; following precipitation, water filters through the upper layers of the soil, extracting minerals and organic material en route. For example, rainfall on chalk areas will result in a supply of water with a high dissolved solids content, high alkalinity and total hardness, whereas the opposite is the case when rain falls on granite. In marshlands and peaty areas water may be pale yellow in colour and will contain appreciable amounts of dissolved organic matter. Such water is sometimes termed 'humic' (because the yellow colour derives from the humic and fulvic acids present) and is likely to possess an unpleasant odour and bitter taste.
The term 'hardness' refers to the presence of calcium and magnesium salts. Temporary hardness is due to the presence of the bicarbonates of calcium and magnesium and permanent hardness to calcium and magnesium chlorides, sulphates and nitrates. Total hardness, as might be expected, is the sum of temporary and permanent hardness. Measurement is expressed as the equivalent concentration of calcium carbonate in milligrams per litre or parts per million (m/v) and is also termed 'degree of hardness'. Approximate classifications are
Medium-soft Hard Very hard
Water for use in soft drinks should ideally be soft or medium-soft.
The standard form of water purification involves treatment in a continuous manner with a coagulent (e.g. Al2(SO4)3, Fe2(SO4)3) and chlorine, together with lime to reduce the alkalinity as necessary (Figure 5.2). A gelatinous precipitate or 'floc' forms (hydroxides of Al or Fe) which absorbs foreign organic matter. The chlorine sterilises the water by virtue of its microbiocidal and oxidising properties.
After treatment, water is passed through a sand filter followed by an activated carbon filter to remove traces of chlorine, and then through a 'polishing' filter (usually a cartridge filter of pore size <10 ^m).
< 50 mg/l as CaCO3 50-100 mg/l as CaCO3 100-200 mg/l as CaCO3 200-300 mg/l as CaCO3.
5.5.5 Water impurities and their effect
Suspended particles may consist of complex inorganic hydroxides and silicates or, sometimes, organic debris. Particles too small to be easily distinguished can cause difficulties when a drink is carbonated, acting as minute centres of instability resulting in a loss of carbonation, foaming (gushing) at the filler-head and variable fill volumes.
In non-carbonated drinks there may be visible deposits, and sometimes a neck ring in the finished product, caused by agglomeration of smaller particles. Filtration of the incoming water stream is therefore essential.
Organic matter is most likely to be present when the water is from soft regions and from surface water reservoir fed supplies. The organic material may include humic acid, algal polysaccharides and polypeptides, protozoa and microbial contaminants. The result is often unsightly porous crystalline precipitation during storage as the organic species, notably algal polysaccharides, respond to the lower pH conditions of the soft drink or react with other components in it.
High alkalinity is due to the presence of bicarbonates, carbonates and hydroxides of the alkaline earth and alkali metals, principally calcium, magnesium, sodium and potassium. The effect of high alkalinity is to buffer acidity in a soft drink, resulting in the creation of a bland taste. It is essential therefore to maintain a consistent alkalinity level. The majority of manufacturers aim for below 50 mg/l as CaCO3. Alkalinity may be reduced by coagulation treatment or by ion exchange.
With modern methods of intensive farming in which nitrate-based fertilisers are employed, there has been a noticeable increase in nitrate levels from aquifers lying beneath agricultural land. The recommended limit for nitrate has been given as 50 mg/l by the World Health Organization (WHO). The principal health risk of nitrates involves a condition seen in infants known as methaemoglobinaemia.
The use of acidulants is an essential part of beverage formulation, with the acid component usually third in order of concentration. Acidulants performs a variety of functions in addition to their primary thirst-quenching properties, which are the result of stimulation of the flow of saliva in the mouth. Because it reduces pH, an acidulant can act as a mild preservative and in some respects as a flavour enhancer, depending on the other components present. In addition, by functioning as a synergist to antioxidants such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT) and ascorbic acid, acidulants can indirectly prevent discolouration and ranciditye.
In carbonated beverages there is the additional effect of dissolved carbon dioxide gas. Although it is not officially recognised as an acidulant, the inclusion of carbon dioxide, under pressure, will certainly provide extra sparkle, mouthfeel, flavour and sharpness in a drink.
Table 5.2 lists the most commonly encountered acidulants.
Citric acid is the most widely used acid in fruit-flavoured beverages. It has a light fruity character that blends well with most fruit flavours, which is to be expected as it occurs naturally in many fruit types. For example, unripe lemons contain 5-8% citric acid. It is also the principal acidic constituent of such fruits as blackcurrants
100 CHEMISTRY AND TECHNOLOGY OF SOFT DRINKS AND FRUIT JUICES Table 5.2 Acidulants used in beverages formulations
Citric acid, 2-hydroxy-1,2,3-propane tricarboxylic acid,
Tartaric acid (D-tartaric)
2,3-dihydroxy butanedioic acid HOOCCH(OH)CH(OH)COOH
Phosphoric acid orthophosphoric acid H3PO4
Lactic acid (DL-lactic) 2-hydroxy propanoic acid CH3CH(OH)COOH
Malic acid (D-malic)
2-hydroxy butandioic acid HOOCCH(OH)CH2COOH
Fumaric acid trans-butenedioic acid HOOCCH=CHCOOH
Acetic acid ethanoic acid CH3COOH
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