MICROBIOLOGY Study Guide - 2012

CHAPTER 15. FOOD MICROBIOLOGY

15.7. MICROBIOLOGY OF CONFECTIONERY PRODUCTS

15.7.2. Microflora of Finished Confectionery Products

Cream-based products. Creams are widely used in The production of cakes and pastries. Confectionery creams are prepared by whipping the formulation ingredients. During this process, the resulting mass becomes saturated with air, acquiring a foam-like Structure. The most microbiologically stable options are buttercream, which has a low moisture content and a high sugar concentration in the liquid phase, and the "Novy" cream. Conversely, the least stable are "Charlotte" cream (due to increased moisture content, eggs, and milk) and custard. Custard contains flour, which is rich in a diverse microflora. Most frequently, custard undergoes Lactic acid Fermentation.

The chemical composition of creams provides a favorable environment for the proliferation of many microorganisms; consequently, the shelf life of cream-based products is strictly limited. Potential sources of cream contamination include raw Materials (milk, cream, sugar, butter, eggs), equipment and utensils, handlers' hands and clothing, as well as rodents and insects. Cream samples often reveal coliform Bacteria (E. coli, C. freundii, K. mobilis), putrefactive bacteria (P. vulgaris), spore-forming bacilli (B. subtilis, B. polymyxa), micrococci, lactic acid bacteria, and Yeasts. Saprophytic microorganisms cause spoilage and diminish the commercial appearance of these products. The microbiological parameters of cream-based products depend on the initial microbial contamination of the ingredients, personal hygiene of the staff, and the quality of production control.

Pathogenic microorganisms entering the cream can cause infectious diseases and food poisoning. When Staphylococcus aureus multiplies in cream, it produces a range of toxins, including enterotoxin, which causes food poisoning. Staphylococci typically enter the cream via purulent Skin lesions on workers' hands or through airborne droplet transmission. Studies on confectionery products with cream have established that staphylococcal enterotoxin is formed exclusively in the sponge cake layer adjacent to the buttercream, rather than in the cream itself, as previously believed. In flour-based custard, however, the enterotoxin accumulates directly within the cream mass. In products contaminated with Staphylococcus aureus, enterotoxin accumulation occurs at 37 °C within 5–6 hours at a high contamination level of 5 x 10⁶ CFU/g, and within 8 hours at a contamination level of 5 x 10³ CFU/g. At 22–25 °C, the time required for toxin accumulation increases to 10–12 hours. At 5–6 °C, staphylococcal growth and toxin production slow down, and at 4 °C, they cease entirely. Therefore, pastries and cakes must be stored at temperatures not exceeding 5 °C and a relative humidity of 70–75%. Staphylococcal enterotoxin is notable for its thermostability—it is not destroyed by boiling for 30 minutes. An acidic environment is unfavorable for staphylococcal growth: at pH levels below 4.5–4.7, their proliferation is halted. Staphylococci are quite resistant to desiccation and high osmotic pressure, and they can multiply in media containing 40–50% sugar and 8–12% sodium chloride.

Protein-based creams can support the growth of salmonellae and other members of the Enterobacteriaceae family.

Marmalade, marshmallow, and cream fudge. The surfaces of these confectionery items are most frequently colonized by mold Fungi of the genera Rhizopus, Mucor, Penicillium, and Aspergillus. To prevent the growth of these fungi, it is recommended to package marmalade in parchment paper treated with a 1% sodium benzoate solution or a 0.4% sorbic acid solution.

Chocolate. Microorganisms generally do not multiply in these confectionery products due to their specific composition (high sugar content up to 65% and fat content up to 35%) and manufacturing technology. According to sanitary rules and standards, the total viable count (TVC) in plain and dessert chocolate without additives must not exceed 1 x 10⁴ CFU/g, while in chocolate with fillings, it should not exceed 5 x 10⁴ CFU/g. The Yeast and mold count must not exceed 50 CFU/g. The product mass in which the following microorganisms are not permitted is: coliforms — 0.1 g; pathogens, including salmonellae — 25 g. Chocolate should be stored at temperatures not exceeding 18 °C and a relative air humidity of no more than

Glazed candies. Certain varieties of enrobed candies with liqueur fillings or cream fudge are susceptible to microbial spoilage. Signs of spoilage appear by the 3rd or 4th day after production: the candy centers swell and sometimes crack under the pressure of gases produced by osnophilic yeasts of the genera Saccharomyces, Brettanomyces, or gas-producing bacterial species. Mold fungi of the genera Aspergillus and Penicillium may also be found inside these candies.