Investigate The Microbial Content Of Some Bolted Soft Drivels Sold


The bingeing of the carbonated beverage industry as recorded by Desroser (1977) dates back to the closing years of  the 18th century. Joseph Priestly known for his discovery of oxygen became interested in the fixed air that lay over the liquid in fermentation vats in  the brewery near his home. Containing his studies he produced this fixed air (Co2) by pouring acid over chalk upon introducing the gas, usually produced by fermentation into water he obtained a pleasant tasting sparkling water which he described in a publication 1772.

Arwold (1977) stated that Bayjamin Silliman operated an establishment in New Haven (USA) for producing and selling soda water in 1807 and by 1860, the census reported 123 plants producing carbonated drink and drink the civil war the following flavors  for soda water were promoted fine apple black cheering orange, apple straw beefy lemon, grape etc. at the present time  the flavour rank  according to popularity as follows: cola lemon, lime , orange, grape and ginger ale However many conceivable type of flavour the flavour rank according to popularity as follows: cola lemon- lime, orange, grape and ginger ale. However, many conceivable type of flavour has been produced. Cola out ranks by for in preference all the other flavors., the structure of the soft drink industries is much the same in most countries in the would has been produced. Cola out ranks by far preference all the other flavours

The structure of the soft drink industries is much the4 same in most countries in the would. As recorded by Houghton (1981) it is dominated by eight major international franchising companies: Coca-Cola, Pepsi, Schweppes, 7 up, canade dry, Dr pepper, Royal crown and crush. These companies hold the trademark and license for local bottling companies to produce for  distribute and sell the product in their area. In Nigeria many of such company exist producing different kinds of soft drinks some of  these are coca cola, Pepsi,  Miranda, Schweppes, faint, crush bitter lemon and Goldnspot.

Cocoa cola was formulated in 1886 by Dr John peubeton. A pharmacist in Atlanta Georgia. The drink was sold as a refreshment at the feuutain center of Jacob pharmacy, of which Dr. Pembeton was  part owner eventually, Asa candler because sole right to the soft drink candler began selling the bsynub used to make the drink to other Pharmacies, established a soles force and begar advertising the drink on sign placed in train station .

candler was granted the first bolting franclish for the drink in 1899, believing that the future of the drink rested with fountain sales (Charles and Gareth, 1995)


Generally the process of manufacturing comprise of the preparation of syrub, adding acidulate. Flavorings and blending the mixture of ingredients. The flavoursed syrub and decorated water are pumped through different channel. The syncroumeter measure and deliver the synub and  water in fixed proportion to the bottling or canning live for packaging. The water used in carbonated beverages is carefully selected for portability. (Herschdoerfer 1986) if water is found to be too hard it is softened and generally treated with either activated charcoal or ozone or both to rid off foreign dours and other content the carbonation of the beverage is carefully controlled by the bottler. If the liquid in the crowned bottle contain both carbonioxide and air it will give up it air suddenly when the bottle is opened and the liquid may boil violently from the bottle (potter 1978). The above manufacturing processes is generally achieved by (1) Syrub manufacturing  (2) Beverage manufacturing (3) Bottling

  • SYRUS MANUFACTURING: this is the addition of sugar to treated water to give the simple syunb which is filtered then the concentrate or beverage base is added along with treated water. It is then finally passed through the filter to produce the synub.
  • BEVERAGE MANUFACTURING: At this stage the synub is convened to carbonated beverages and this is the last step in the material pathways. This air from treated water; proportioning which is the mixture of finished synub and water in a given ratio; and carbonation which is the impregnation of the beverage with carbon dioxide.
  • Bottling: The beverage is bottled in the filling cycle after washing and inspecting this bottles.



Types of micro organisms in soft drink microorganisms which may be present include fungi such as yeast and molds bacteria Algae and protozoa.

Yeast denotes a brand group of fungal microorganisms and are mostly unicellular and reproduce by budding and asexual spores some yeast however reproduce by sexual spones. Yeast are source what larger than bacteria. Their cell wall contains chitin and within the cell is a large vacuole. Yeast grow more reality in  example. Yeast grow more reality in syrub. Beverages solution (the optic PH for yeast growth is 4.0 to 4.5) some flavours, and other beverage raw material, than any other class of microorganisms under the condition customanity  existing during the  manufacturing of carbonated and non carbonated soft drinks. (Witler 1958) consequently it is of the greatest importance  for  the beverage manufacturer to know the details of their occurrence and growth and the factor controlling their growth speck (1984) recorded that the experiment performaned by the national soft drink association over a period of years indicated that in oven 90% of the instances spoilage was due to excessive number of yeast.



Microorganisms are categorized by growth  condition such as oxygen requirement (obligate acrobes) e.g Acetobacter, Bacillus spp. And nearly all mould must have oxygen present while (obligate anaerobe) e.g some species of closhidium and lactobacilli can not survive  in it. Escheirchai coli and most yeast are felcultative anaerobe and can grow with or without oxygen. Other Lactobacillus spp. And Lactic acid bacteria need a little oxygen and are termed micro acripluiles (1to 100c) mesophiles (25 to 37 0c ) and thermopile (up to 800c) these definition are not rigid E coli is mesophile with a typical optimum growth temperature of 370c but strains from non- enteric habitats will grow better at lower temperatures. Most yeast are incubated at 250c to 27 0c many grow at 5 0c some are thermodinic surviving over 700c and other are obligate psychopliles (range 0 to 150c) and up to 250c). the latter  are generally not found in soft drink (Batchelor 1985) when different microbial genra species or strains are present the resulting population is described as a mixed culture. A pure culture devotes the presence of a single species or strain under ideal condition a pure culture of any  unicellular micro organisms has a growth curve, that usually can be dividual into four characteristic phases. This curve, shower in fig 1 could represent the growth rate of cells of a particular feast strain that have entered a container of soft drink during bolting.

Batchelor further stated that in lag phase (fig1) only a few viable cells are present initially possibly only one. The population adopts to it environment and start to grow the logarithmic or log phase occurs when the population increase most rapidly doubling itself at a constant of generation under favourable condition rapidly growing yeast strains can double their number every 30 mins while slow growers have mean doubling time of move than 10 hours. The end of this phase is due to various limiting factors such as lack of available nutrient or number of cells produced equal the number of dying cell the station any phases reached. Eventually the death rate increase and this result in the decline phase time

  1. INTRINSIC FACTORS: They are derived from nature of product and its formation these are :
  • Water activity (AW): This is defined this
  • AW = water vapour pressure of product

Vapour pressure of pure water at same terp.

Soft  drink have AW of about 0.90 to 0.95, this encourage the growth of some organisms like bacteria  and (Aw range of 0.93 to 0.99, most yeast (Aw rang of 0.85 to 0.99) (R.R Davenport, 1980) yeast are likely to spoil liquid products.

  • Microbial Nutrients: In addition to water microorganisms needs other nutrient mineral element like carbon, nitrogen etc. the limiting effect of available nitrogen level is particularly important in soft drink. Beverage with higher levels, present in natural ingredient such as fruit pulp and caramel colours are more susceptible to spoilage by a wider range of microorganisms.
  • Microbial inhibitors: Present as constituents of natural plant extract and are effective in conjunctive with other factors in soft drink eg citrus oil constituents a highly carbonated beverage carbonates cola type drinks.
  • Acidity: in term of PH acidity is one of the most important single intrinsic factor in soft drink spoilage (Korab and Dobbs, 1984) generally soft drink have pH values of between 2.0 4.5 most bacteria grow best at PH ranging  from 6.0 to 8.5, However, some bacteria grow well at soft drink PH level. Usually these general are member of the acetic acid or lactic acid groups. (Davenport 1980) also recorded that yeast and moulds have the optimum PH range of 4.0 to 6.0 but several yeast grow in soft  drink at pH 3.0 to 4.0 and some can grow in the range 1.5 and 3.0.
  • Carbonation: Carbonation as a method of preserving soft drink is effective at over 2.5 or 3.0 volumes of Co Batchelor (1980) recorded that its activity is linked to other  factors and depend masuly upon p H sugar initial microbial load and upon the mature of the microorganisms. Insulate also studies the effect of carbondioxide on yeast and  discovered  that the degree of its effectiveness is greatly affected by the sugar level content of the beverage. Carbonation inhibits growth of acerbic microbes such as acetic acid bacteria and the natural bacteria flora of mineral water facultative  anaerobic microbial such as yeast and some of the lactic acid bacteria, die more slowly or are apparently unaffected.
  • Preservatives: The choice of preservation and its concentration represent the most easily adjustable “hurdle: it is therefore month careful consideration although it can be dealt with only briefly how. Preservative addition should not be required addition since as substitute for good manufacture practice poor hygiens will encourage the development of resistant microorganisms. However if preservative are needed they are best used in the largest concentration possible because the use of lower level concentration increases the risk of adaptation and subsequent growth Naturally legal limits must be observed. Well know preservatives are sulphur dioxide, benzoic and sorbic acids (Batchelor 1980).


  • Nature: condition and Number of microorganisms the nature and condition of the microbes is clearly paramount since relatively few general can spoil soft drink. Among these are some sporogenous yeast. Yeast ascospores are more resistant than vegetatives cells to  desecration or sterilization and this factor has been recognized in laboratory challenge test. The initial microbial load before processing reflect the quality of the raw materials, handling and possibly plant hygieve. If cents are too high then processing may be ineffective and poteutial spoilers could grow in the  inal product even from very low number of cell.
  • Processing : The objective of processing is to achieve the absence of all medically significant microorganisms (pasteurization or disinfection) plus any potential spoilers. Consequently such process are design to give commercial rather than absolute sterility. Suitable for soft drinks are filtration or exposure to heat or the chemical. If the internals to be processed or the processing equipment contains sufficient debnis then process may be inactivated therefore a high standard of cleanliness is  essential (Harry and Wilbert 1984)
  • Packaging materials: Among the best know problem associated with traditional packaging is contamination of glass bottles from incorrectly used bottle washers. Others are contamination of crows by crowned head and of cans via leading seams on pinholes caused by over deep embossing.



Fraizer and Westhoff (1988)  stated that the ingredient of soft drink not only affect the suitability for microbial growth but also can affect the kind and number of microorganisms present and hance the likehood of spoilage organisms been added. They added that one worker found that 85% of 1,800 spoiled sample by yeast since the sugar possible source of yeast. The American  bottle of carbonated beverages. Have set a standard of hot move than 10 yeast are another possible  cause of yeast since molds must have air, they can not grow on carbonated beverages but may develop at the surface of uncarbonated ones  containing air above the liquid. They may come from sugar coloring material or flavoring material from the air or bottles or closures other soft drink ingredients have relative other soft drink ingredient have relatively hight interstice stability du to their low available water (eg power, oil alcoholic extract) plus the action of food preservatives (e.g emulsion). Ingredient are ramely sterile though and their microbial load however small may be significant bachelor, 1980).

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