Microbiology of soft drinks and fruit juices

Microbial problems within soft drinks and fruit juices can be divided into 

There is a bewildering variety of soft drink and fruit juices for sale, and many methods for their manufacture. Soft drinks can be non-carbonated, carbonated, 

Sugars have a protective effect on the heat resistance of yeasts and bacteria this is an important consideration at higher concentrations of sugar. Soft drinks are often nitrogen poor and thus the addition of fruit juice greatly enhances the potential for spoilage. Some yeasts, for example Dekkera bruxellensis, can use nitrate. Phosphate levels are often low, trace minerals satisfactory, particularly in haid water areas. Tire low pH value of soft drinks and fruit juices, pH 2.5-3.8 (Table 11.1), inhibits most bacteria, but leaves yeasts unaffected. In soft drinks 

The recent trend towards polyethylene terephthalate (PET) packaging presents its own problems. Typically PET containers cannot be hot filled around 50°C is the upper temperature, although some recent types can be heated to 85°C. They are also permeable to oxygen (Rodriguez el al., 1992), which allows the growth of aerobic spoilage agents. 

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Davenport, R.R. (1998) Microbiology of soft drinks, in Chemistry and Technology of Soft Drinks and Fruit Juices, 1st edn. (ed. RR. Ashurst), Sheffield Academic Press, Sheffield, UK and CRC Press, Boca Raton, FL, pp. 197-216. 

Stratford M., Hofman P.D. and Cole M.B. (2000) Fruit juices, fruit drinks, and soft drinks, in The Microbiological Safety and Quality of Food, Vol. 1 (eds B.M Lund., T.C Baird-Parker and G.W. Gould), Aspen Publishers, Gaithersburg, pp. 836-69. 

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