MICROBIOLOGY Study Guide - 2012

CHAPTER 15. FOOD MICROBIOLOGY

15.11. MICROBIOLOGY OF NON-ALCOHOLIC BEVERAGES

The core ingredients of beverages include drinking Water, natural fruit and berry juices, syrups, citrus fruit infusions, organic acids, essences, and colorings. Tonic beverages additionally incorporate extracts and infusions of certain plants. Several beverages are prepared using mineral waters. No specific microflora is introduced during The production of non-alcoholic beverages.

Bacteria can multiply in mineral water devoid of C0₂. After 1 to 6 months of storage at room Temperature, the microbial count may increase by a factor of 10³ to 10⁴ per 1 cm³. The microflora of these beverages typically comprises Representatives of the genera Pseudomonas, Alcaligenes, Flavobacterium, Xantomonas.

Beverages that are sugar-free and carbonated with carbon dioxide do not provide favorable conditions for microbial proliferation; nevertheless, the microbes present within them can remain viable for extended periods. Empty bottles, closures, storage tanks, transport containers, pipelines, and bottling machines have proven to be the most Common sources of beverage contamination. Various Methods have been proposed to eliminate microorganisms from mineral water, including filtration, silver Treatment, ozonation, and pasteurization. Only hygienically immaculate bottles and closures must be used for bottling. Storage should take place in dry, clean, dark rooms at a temperature of 2—15 °C. Continuous microbiological control is essential at all Stages of the manufacturing process.

Beverages containing fruit juices, lemonades, and carbonated waters with sugar are less microbiologically stable than sugar-free, C0₂-saturated waters. Microorganisms cause a decline in beverage quality, specifically flavor deterioration, turbidity, and Fermentation. They adversely affect product stability and can lead to total spoilage.

The multiplication of bacteria in fruit juice beverages, lemonades, and carbonated drinks is significantly influenced by oxygen availability and active acidity. The lower the pH of a beverage, the lower the likelihood of bacterial spoilage. In carbonated beverages, the growth of aerobic bacteria is heavily suppressed. Lactic acid and acetic acid bacteria are the most frequent proliferators in lemonades and fruit juice beverages. Aroma-producing lactobacilli accumulate diacetyl and acetoin, which impair the flavor and aroma of the drink. The Development of Leuconostoc mesenteroides is particularly undesirable, as it produces copious amounts of slime by converting sucrose into the polysaccharide dextran. Beverages contaminated with this microbe acquire a viscous, thick, mucilaginous consistency.

Yeasts are most frequently encountered in refreshing, sugar-containing beverages. They cause turbidity, sediment formation, and product fermentation. Yeasts of the genus Saccharomyces—specifically S. cerevisiae, S. acidofaciens, S. italicus—along with yeasts of the genera Candida, Torulopsis, Pichia, Brettanomyces, have proven to be the best adapted for multiplication in such beverages. Mold Fungi practically fail to develop in various non-alcoholic beverages due to their high oxygen demand. However, less oxygen-demanding mold fungi, predominantly representatives of the genera Mucor and Fusarium, are capable of causing beverage spoilage. The proliferation of micromycetes can be visually identified by the presence of a surface film or suspended, cotton-like mycelial flocs. The beverage acquires a moldy taste and odor.

The Use of microbially contaminated raw Materials and water, bottling into improperly washed containers, and violations of Sanitary and hygienic production standards lead to the development of extraneous microflora, resulting in beverage turbidity, sediment precipitation as flocs, and a fermented off-flavor. Pathogenic microorganisms are strictly prohibited in beverages, and sanitary-bacteriological parameters must comply with applicable health standards and regulations.

To enhance the biological stability of beverages, they are subjected to pasteurization or treated with preservatives approved by public health authorities (sorbic acid and its salts, sodium benzoate, juglone, plumbagin, etc.).

Depending on the type of non-alcoholic beverage, the required storage stability ranges from 10 to 30 days, and up to 6 months for pasteurized fruit juice beverages in bottles or bulk containers. This is primarily determined by the microflora of the finished product, which depends on the degree of microbial contamination of the raw and auxiliary materials, the sanitary-hygienic regime at the facility, and storage conditions.