Soft Drinks

This article describes the broad outline of making soft drinks, from raw materials and syrup preparation to bottling.

Soft drinks

Soft drinks are beverages produced from (mineral) water with sugar or sweeteners. Generally, soft drinks contain carbon dioxide. The carbon dioxide has three functions:

  • It provides a cooling sensation: through the evaporation of the gas heat is extracted from the tongue.
  • It lowers the degree of acidity (pH 2.2 - 3.6), slowing down the growth of microorganism. However, other preservatives may be added in addition.
  • It poisons the air that is possibly present above the soft drink, making it impossible for fungi to grow, due to the lack of oxygen.

If the product does not contain any carbon dioxide, it is considered a ‘flat’ or "still" drink. Additionally, flavourings, fruit- and plant juices, edible parts of fruits or plants and acid are added. Mineral water itself also belongs to the group of soft drinks.

Since the production process is very similar, the term ‘soft’ also applies to value added products, such as energy drinks and isotonic drinks. The market of refreshing beverages based on whey is showing a strong growth. There is also an strong increase visible in the number of ‘light’ soft drinks. Sweeteners are added to these drinks, replacing the sugar and thus lowering the consumers’ calorie intake. Acesulfame, cyclamate, aspartame and saccharin are the only sweeteners allowed.

Soft drinks make up for a large part of the non-alcoholic drinks category.

The Dutch Commodities Act sets a number of requirements for the labeling and naming of soft drinks:

  • Mineral water: Mineral water extracted from a source and bottled at the source.

  • Fruit Lemonade: Whether it is a carbonated beverage or not, with less than 0.5% of alcohol, it has to consist of water, sugar, and between 10 to 25% fermented or non-fermented fruit juices. Only organic acids, flavouring extracts and / or natural aromas are allowed to be added. The sugar, sucrose or glucose level, should be between 7 and 15%. Artificial sweeteners are not allowed.

  • Tonic: The presence of quinine should be indicated on the product label. In addition to a sugar content of more than 5%, the product must contain at least 40 mg of quinine per liter.

  • Lemonade-aerated: A bright, fizzy drink with a sugar content of at least 8%, in which the use of artificial colourings and flavours is allowed. This product does not contain any juice.

  • Caffeinated aerated: The presence of caffeine must be listed on the product label. These products may contain up to 150 mg of caffeine per liter, and may only be manufactured with ortho-phosphoric acid, to a maximum level of 600 mg per liter.

Soft drink production process

Systems for the production of soft drinks generally consist of a storage tank (a silo for the storage of the raw materials such as sugar, colouring and flavouring agents), a water treatment unit, a mixer, a pasteurizer or UHT sterilizer, a system for the adding of carbon dioxide and filling line. All systems can be cleaned automatically, by means of CIP (Cleaning In Place).

Raw materials

Soft drinks mainly consist of water. Due to the possibility of a chemical reaction between the calcium and other minerals in the water, and the colouring and flavouring agents, it may be necessary to soften and filter the water. It is important that the bacterial count of the water is sufficiently low.

  • Drinking water is not free from micro-organisms. By law, the drinking water provided by the water company, must meet the 10 cfu/ml (measured at 22°C) at the supply point of the water company. The absence of organic carbon (clean water) prevents these microorganisms from growing further. As soon as sugar is added, microbial growth is triggered.

Sugar can be supplied in solid or liquid, in syrup form. The flavour of the product is determined by its sweet and sour ratio. For this reason, in addition to sugar, often an acid is added to the product. Next to citric acid, in the production of cola also phosphoric acid may be used.

  • Sugar syrup is microbially stable at 70°Brix. This means that that the sugar content is so high that any microorganisms present cannot withdraw any water from the syrup in order to grow. In fact, the water from the microorganisms themselves is extracted and they dehydrate. A large number of microorganism species do not survive at high concentrations of sugar.

  • However, condensation falling on the sugar syrup allows spores that are present there to grow into living and dividing microorganisms. If a sugar syrup tank is not isolated well, substantial amounts of mildew are found on the surface of the tank.

Syrup Production

The basis of soft drinks, the syrup, is made up of water, sugar, acid, colouring and flavouring agents. This syrup is prepared by dissolving these ingredients into water to 65°Brix.

Sugar can be dissolved in two ways:

  • Warm: dissolving at 70 to 80°C, filtering and cooling to 15°C
  • Cold: dissolving by intensive stirring in cold water, filtering, and pasteurising.

Usually, the sugar is added with a flow meter. With the help of a flow meter with a density measurement (mass flow meter) the sugar content can be measured directly. The density is a measure of the sugar level (also called Brix). The Brix value represents the weight percentage of sugar in the food product. ? In the following table of Oechsle/Brix, the relationship between the density and the Brix value is given.

°Brix Dichtheid bij 20°C °Baumé °Brix Dichtheid bij 20°C °Baumé
1 1.00389 0.56 38 1.16833 20.89
2 1.00779 1.12 39 1.17341 21.43
3 1.01172 1.68 40 1.17853 21.97
4 1.01567 2.24 41 1.18368 22.50
5 1.01965 2.79 42 1.18887 23.04
6 1.02366 3.35 43 1.19410 23.57
7 1.02770 3.91 44 1.19936 24.10
8 1.03176 4.46 45 1.20467 24.63
9 1.03586 5.02 46 1.21001 25.17
10 1.03998 5.57 47 1.21538 25.70
11 1.04413 6.13 48 1.22080 26.23
12 1.04831 6.68 49 1.22625 26.75
13 1.05252 7.24 50 1.23174 27.28
14 1.05677 7.79 51 1.23727 27.81
15 1.06104 8.34 52 1.24284 28.33
16 1.06534 8.98 53 1.24844 28.86
17 1.06968 9.45 54 1.25408 29.38
18 1.07404 10.00 55 1.25976 29.90
19 1.07844 10.55 56 1.26548 30.42
20 1.08287 11.10 57 1.27123 30.94
21 1.08733 11.65 58 1.27703 31.46
22 1.09183 12.20 59 1.28286 31.97
23 1.09636 12.74 60 1.28873 32.49
24 1.10092 13.29 61 1.29464 33.00
25 1.10551 13.84 62 1.30059 33.51
26 1.11014 14.39 63 1.30657 34.02
27 1.11480 14.93 64 1.31260 34.53
28 1.11949 15.48 65 1.31866 35.04
29 1.12422 16.02 66 1.32476 35.55
30 1.12898 16.57 67 1.33090 36.05
31 1.13378 17.11 68 1.33708 36.55
32 1.13861 17.65 69 1.34330 37.06
33 1.14347 18.19 70 1.34956 37.56
34 1.14837 18.73 71 1.35585 38.06
35 1.15331 19.28 72 1.36218 38.55
36 1.15828 19.81 73 1.36856 39.05
37 1.16329 20.35 74 1.37496 39.54

When instead of sugar, sweeteners are added, the required sweetness is determined through measuring the electrical conductivity of the solution. Measuring the density will not give accurate results due to the low density change of the solution.

The order in which the other ingredients are added varies per recipe. The colouring and flavouring agents and acids are usually only added in low concentrations, and are easy to dose by hand or by dosing pumps. When fruit juices are added to the syrup, the product should be pasteurised before impregnation.

The syrup must be given time to settle, so that any air whipped in can escape. This can also be done by using a vacuum deaerator: a rotating disc or plate over which the liquid (syrup) flows, while the surrounding space is continuously maintained under vacuum. It is also possible to bottle the syrup undiluted. Consumers can dilute the syrup themselves at home and optionally add carbon dioxide.


Syrup with fruit juices or with a pH of 3 or higher must be pasteurized at 80°C for 20 seconds before impregnation. This temperature is sufficient to kill off all living, vegetative cells. Only the spores, a survival mode for a number of species of microorganisms, may still be left behind. As long as the pH is lower than 4.6, they cannot develop into vegetative cells, which can grow further. If the pH turns out to be higher than 4.6, then the product must be sterilised or has a limited shelf life under refrigerated conditions.


Impregnation is the process of mixing water with carbon dioxide. The solubility of carbon dioxide gas in water depends on the pressure and the temperature of the water. The colder the water, the higher the solubility.

Carbon dioxide, however, is more soluble in air than in water. A balance will occur between the carbonic acid in the water and the carbon dioxide in the air. In a vacuum boiler the water is de-aerated as much as possible. After that the water is impregnated with carbon dioxide under high-pressure.

Mixing the syrup and the carbonated water can be done in 3 ways:

  • Premix-method: In this method, two separate filling systems are needed, because the syrup is filled into the bottle before the carbonated water is added.
  • Trimix or Intermix System: With this system, the carbonated water and the syrup are mixed in the proper ratio by using metering pumps.
  • Mixing In-line: During the pumping of the syrup, water is added in-lin. With a static mixer in the pipeline, the solution is mixed well. Checking if the correct mix ratio is achieved can be done by measuring the density of the solution. Subsequently, the in-line impregnation process takes place. After impregnation, the solution is mixed again by a static mixer.

Bottling process

The majority of soft drinks are filled under pressure into bottles (glass or PET) or cans, achieving a maximum CO2-content of 8 grams. After filling, the bottles are immediately closed off with a (sterile) crown cap or a cap with plastic layer. In order to prevent airborne infections, often sterile air is blown over the bottle opening. Sometimes block packaging is applied.

The final step of the bottling process is labeling the packages with a labeling machine.

Food Safety & Hygienic Design

The preparation area must at least comply with GMP: being visibly clean before use, and no long term presence of water remaining after cleaning.

The syrup tank is seldom or never cleaned because of the supposed shelf life. As long as there is no mould growth, this is acceptable. The top of the tank - including manhole and air vent - must be heated and isolated for that purpose.

Pasteurisation is the critical step in the production process to kill off any microorganisms. It is important that this part of the production process is well designed - according to EHEDG-guideline no.1. In order to pasteurise, often a plate heat exchanger is used. It is known that these exchangers - even when new - will start to leak, but even more likely after time. Regular inspection is key in order to make sure the highly deformed thin plates of the plate heat exchanger do not suffer from stress and crack corrosion.

After pasteurisation, the whole line, including filling machine(s), must be hygienically designed: meaning cleanable to microbial level. Unless the product is pasteurized after filling, then GMP is sufficient. However, even this is not a license to be less careful during the pre-processing phase or cleaning the processing equipment less frequently or not fully, or extending the production run. Large amounts of heat-stable toxins produced by microorganisms (in particular of *S.aereus), may still be toxic after sterilization and will form a threat to the health of the consumer.


Soft Drinks Industry Winters

The rich history of Soft Drinks Industry Winters BV is now in its third century. Today, the bottling company is alive more than ever. With a flexible attitude and high quality standards it has become the largest Dutch soft drinks exporter. In addition, the lubricants of Shell Lubricants make the machines run optimally and food safe.

"You ask, Winters fills": that's the motto of Soft Drinks Industry Winters BV in Maarheeze (North Brabant, The Netherlands). The company is not directly known to the consumers: the company has never sold soft drinks under its own name. Still, it can look back on a long and rich history. When William Van Hooff laid the founding stone of his brewery on August 5, 1797, he could not have realised that it would become an international soft drink company in two centuries time. By inheritance to the next generations in the year 1873 Jan Winters came in charge. Since then, the brewery was known by his name. In 1918 the production of soft drinks started. Until 1958 Winters only had regional ambitions. Then the company expanded business and Winters became producer of world renowned branded as Seven-Up, Sunkist and Canada Dry. When the domestic sales of soft drinks stagnated, the sight was set on various foreign markets in the seventies. In 1978 the company became part of TLC Beatrice International Holdings. Together with the Belgian soda bottling Sunco, who belonged to the same group, it took over the French mineral water producer St. Alban in 1996. After a management buyout the holding company Sun Beverages Company emerged in 1998, comprising Winters, Sunco and St. Alban.

Contract filling

In 1989 the licenses for the production of Seven-Up and other branded products for the Dutch market ended. Since then all attention is directed to 'contract filling'. This is done on behalf of major international food companies, retailers and other commercial organizations. Winters fills cans for a range of soft drinks, energy drinks, mixed drinks, juices, waters and beers with well-known brands. Between 5 and 10% of production is destined for its own brands, such as Sun Cola and Orange, Party Cola and Orange, Provita multivitamin drink, Maresca mineral water and Megaforce energy drink. Nearly 95% of the volumes is exported worldwide and thus Winters is immediately the biggest Dutch soda exporter. Every year more than 500 million cans are filled, packed and logistically processed. Winters currently employs 120 people in permanent employment and dozens of seasonal workers. Production runs per working day in three shifts for 24 hours and during the peak season in a four or five shifts.

To realize such large numbers, Winters has three production lines. An important part of each line is the can sealing machine running at very high speeds. Two machines seal 1,200 filled cans per minute and the third will do another 625 units per minute. Frans Cox, head of utilities and engineering projects: "Such devices are very capital intensive. It is very important that they remain in good condition to produce an excellent product with a constant quality. "

For the reliability of the sealing machines the right food grade lubricants are essential. Some parts are lubricated with oil, others with grease. Oils are able to dissipate more heat and are regenerable by filtration. They are applied for the lubrication of (plain) bearings and gears. Fats are oils encapsulated in soap skeleton. They have less heat-dissipating properties, and can not be reused. The fats serve, inter alia, for the lubrication of bearings in hemming rollers. Incidentally, their lubricating frequency is lower than that of oils.

One supplier

Until ten years ago, Winters used lubricants from various manufacturers. F. Cox: "However, the need hasd arisen to rationalise the diversity of products and providers. To get a better overview, we decided to give one person decision-making authority and to work with just one supplier. The result is that if there are questions, there is only one firm where you can go to the right person. That's an advantage, because of the high speeds the machines are very sensitive and, if necessary, you should be able to rely on a rapid intervention of your lubricant supplier."

Arjan Nieuwstraten, food sector specialist of Shell Lubricants, adds: "The material of a modern beverage can is much thinner than before and therefore the method of sealing is more critical. So you can imagine the tolerances to have to work with will be smaller than before. The importance of the lubrication is thus become much greater. "

At that time Winters already bought around 70% of its lubricants from Shell Lubricants and, partly by this collaboration this supplier was chosen. "The people at Shell were always coming into action directly when needed. They were also always ready for the start up of new equipment, switching to newer oils or fats, assistance in making lubrication schedules, etc. That's why we did not have to think long about who we wanted to go into business with", F. Cox continues.

In practice, there is now a 'gentlemen's agreement' between the two parties. "A synergy has grown between our companies, based on years of trust", A. Nieuwstraten confirms. "The collaboration with Shell Lubricants is closely aligned with the expectations that we have with respect to our suppliers", F. Cox adds.

Incidentally Shell offers Winters an additional service with the Lubriplan software. This lubrication management system provides an accurate overview of the inspection points for fats and oils in the machines and generates user-friendly instructions. So it is indicated where and with what frequency there has to be checked or lubricated and with what product that needs to be done. "Moreover Lubriplan builds up a history of the objects to be lubricated. It may sometimes appear that periodic lubrication at a certain location is needed less frequent than planned. Such cost optimisations we do proactively for Winters", A. Nieuwstraten continues.

Food safety

In this industry, food safety is of paramount importance and it is essential that no contamination of the filled product occurs. The past decades mineral (engine) oils were used to lubricate can seaming machines. Because these are unfit and improper to come into contact with food, Shell Lubricants has developed a range of food grade oils and fats which are suitable for the lubrication of such equipment. They may be used in the food industry and meet the European standard and the US FDA NSF H1-H1. The FDA (Food and Drug Administration) considers incidental contact of these lubricants with the food product to be acceptable to a level of 10 ppm (parts per million). The lubricants are food safe without compromising on their lubricating properties.

Incidentally, there are two types of food grade products. In some sealing machines the lubrication takes place in a closed circuit: this process is called "recirculating oil '. For such systems Shell Lubricants has developed the synthetic oil 'Shell Cassida Fluid GLE' series. That series has excellent lubricating properties and is recognized by leading suppliers of sealing such as Angelus (USA), FMC FoodTech (Belgium) and Ferrum (Switzerland). A second process is that wherein the lubricant is used only once: the "total-loss system. For this, Shell introduced the food grade mineral oil 'Shell FM Gear Oil TLS 150'. That delivers outstanding performance, even in the presence of water, juice or beer. Moreover, this oil absorbs water, preventing rust.

Remarkable is that these Shell products were developed in cooperation with Soft Drinks Industry Winters. A. Nieuwstraten: "We gave attention both to food security and to the optimization of lubricant performance. At Winter we have gained a lot of knowledge about the lubrication of sealing machines with these products and numerous tests have led to the most sophisticated lubricants for this sector."

Quality Systems

Large beverage producers that have known branded products manufactured through contract fillers not only value high the quality of the final product. Also, the extent to which the production process is controlled and hygiene risks are avoided, plays a major role for them. Winters has responded and holds international quality certificates according to ISO 9000, 14001 and HACCP (hazard analysis critical control points). In addition, the bottling company is certified to the BRC standard (British Retail Consortium). That standard contains guidelines which food producers have to meet in order to supply the large English supermarkets. Finally, for German and French retail chains Winters has the IFS certificate (International Food Standard).

With the high quality food grade lubricants of Shell Lubricants and the high quality standards of Winter the consumer profits.

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  • Pasteurisation - sterilisation
  • Soft drinks - syrups
  • Beverage
  • Sugar