INCIDENCE AND CHARACTERIZATION OF BACILLUS CEREUS IN MEAT AND MEAT PRODUCTS CONSUMED IN TURKEY

A total of 100 retail samples of meat and meat products were examined for Bacillus cereus using mannitol egg yolk polymyxin (MYP) agar as a selective isolation medium. Only 22.4% of the samples contained detectable levels of B. cereus, with counts ranging from log₁₀ 0.69 to 4.80 cfu/g, but a large number of other organisms up to log₁₀ 9.06 cfu/g were sometimes observed on the plates and may have masked the presence of B. cereus or inhibited growth. Two samples of soudjouck contained significant levels of B. cereus, sufficient enough to create a public health hazard. Selected isolates were tested for diarrheal enterotoxin production by a reversed passive latex agglutination (RPLA) test kit. Results showed no difference in the toxin production of B. cereus between beef, ground meat, soudjouck and pastrami samples. Plasmid‐profile analysis and susceptibility to the six commonly used antimicrobial agents were done on selected B. cereus isolates. About 96.4% of the isolates contained plasmids. Plasmid sizes ranged between 2.5 and 3.5 kb. The isolates showed a high rate of resistance to oxacillin (OXA) and amoxicillin (AMC) and a low frequency of resistance to the other antimicrobial agents, with all of them being susceptible to vancomycin (VAN). Approximately 54% of the isolates showed multiple resistance. There was no apparent relationship between drug resistance and carriage of plasmids.     

THE EFFECT OF CINNAMON AND GUAR GUM ON BACILLUS CEREUS POPULATION IN MILK

Milk was inoculated with Bacillus cereus and the effect of cinnamon and guar gum on B. cereus counts in ultra high-temperature milk was examined by storing samples at 4 and 25C and determining microbial counts as total bacteria by plate count agar at 0, 7, 14 and 28 days. Cinnamon with or without guar gum did not significantly affect B. cereus count at 4C, but it reduced B. cereus counts of milk compared with B. cereus counts of control milk at 25C. Increasing cinnamon concentration from 0.5 to 1% increased antimicrobial effect at the starting of storage but did not affect final B. cereus count. Cinnamon shows antimicrobial activity with their essential oils penetrating through food medium to the microbial cell so the viscosity of food medium caused by stabilizers is a factor that can affect the diffusion of antimicrobial agents through medium to microorganisms and was determined by rotational viscometer. The viscosity of milk with guar gum (0.5%) was found higher than the viscosity of milk that was not including guar gum, but at the end of 28 days the B. cereus counts of milk with guar gum and cinnamon were not higher than the B. cereus counts of milk with cinnamon alone at 25C.

PRACTICAL APPLICATIONS

Naturally occurring food grade cinnamon with antimicrobial properties can reduce Bacillus cereus count of flavored milk like chocolate milk stored at room temperature and then allows flexibility against storage of flavored milk. As cinnamon acts as the antimicrobial agent alone, it can also be added into flavored milk with guar gum being the stabilizer that does not affect the antimicrobial effect of cinnamon.     

FACTORS INFLUENCING THE INCIDENCE OF B. CEREUS SPORES IN MILK

The many factors involved in the contamination of milk with B. cereus cells and the importance of minimizing the number of spores at the time of pasteurization are discussed. Methods of controlling the level of B. cereus spores and the use of heat in the cleaning and sterilizing operation are shown, and studies on the level of aerobic spores in raw milk supplies showing a seasonal effect evaluated.     

BACILLUS CEREUS IN SOME INDIAN FOODS, INCIDENCE AND ANTIBIOTIC, HEAT AND RADIATION RESISTANCE

Samples of 124 different foods purchased from local markets were examined to determine the incidence of Bacillus cereus. The foods examined were pulses, rice and rice products, oils, fish, meat, spices, milk and milk products and ice creams. Isolations were made on mannitol-egg yolk-polymyxin B agar medium and confirmed by morphological and biochemical tests. B. cereus was present in 28.5% of rice and rice products (100% of boiled rice), 40% of fish, 80% of chicken and meat products, 30% of spices and 87% of ice creams. Pasteurized milk and milk products and protein-rich food powders containing milk or cocoa were also contaminated with B. cereus. The average count of B. cereus varied from 2 × 10² to 5 × 10⁵/g. The response of cells and spores from 6 randomly selected isolates of B. cereus to antibiotics and to heat treatment was identical. However, both vegetative and spore forms of these isolates exhibited subtle differences in radiation resistance. Pathogenicity of all isolates was determined by their ability to lyse human erythrocytes. Five of the six isolates selected produced a strong nonhemolytic toxin which is lethal to mice.     

蜡样芽孢杆菌在营养肉汤中的生长模型

蜡样芽孢杆菌是一种易引起人类食物中毒的致病菌,在自然界中广泛存在.主要研究在不同温度下蜡样芽孢杆菌在营养肉汤中的生长状况,建立15℃-44℃下蜡样芽孢杆菌在营养肉汤中的生长模型.     

CONTROL OF BACILLUS CEREUS IN HIGH-pH CRUMPETS

Studies were performed to determine the effects of sorbic hydroxamic acid (SHA) and mastic oil–ethanol (ME) or water‐ethanol (WE) emitters on the growth of Bacillus cereus in high‐moisture, high‐pH (～8.9) English‐style crumpets stored at ambient temperature (25C). While SHA (3000 p.p.m.), alone or in combination with ME emitters, was effective in inhibiting the growth of B. cereus for 14 days in high‐pH crumpets, only SHA formulated crumpets packaged in air had acceptable sensory scores at the end of storage. However, ME emitters alone were ineffective in controlling the growth of this pathogen. This lack of inhibition in crumpets was attributed to the poor absorption of mastic volatiles from the package headspace into the food matrix. Whatever the reason, these preliminary studies showed that SHA has the potential to control the growth of B. cereus in high‐moisture, high‐pH crumpets without compromising product quality.     

THE FUTURE OF UHT MILK AND MILK PRODUCTS IN EUROPE

The development of packed milk relative to total milk consumption in Switzerland from 1958-76 is illustrated and the future of the industry in Continental Europe considered. Decrease in milk consumption in both Switzerland and Germany and the limitations of climatic conditions and transport are discussed and the advantages of UHT long-life milk evaluated. The potential in an increasing market for UHT milk products and in aseptic filling machines is assessed. ( Editor's summary ).     

THE NUTRITIONAL IMPORTANCE OF MILK AND MILK PRODUCTS IN THE NATIONAL DIET

The average consumption of milk and milk products is related to their composition and to the recommended intakes for nutrients, and the nutritional importance of dairy products is considered. The major contribution to the average diet is in the protein, calcium, riboflavin and vitamin A contained in dairy products.     

ADVANCES IN THE MICROBIOLOGY OF MILK AND DAIRY PRODUCTS

The techniques of microbiology from the seventeenth century up to the present time are reviewed and the problems of disease in dairy herds with its effect on raw milk supplies assessed. Progress in the cleaning of milk vessels and sterilization is detailed and the history of pasteurization with its affect on the keeping quality of milk is shown. The introduction of starters in cheese manufacture during the last century is described and the important advances made are stressed.     

ADVANCES IN THE CHEMISTRY OF MILK AND DAIRY PRODUCTS

Present knowledge of the chemistry of the fat and proteins of milk is reviewed briefly in relation to properties of milk and dairy products of commercial importance. The dietary factors affecting milk composition and the chemical and physical changes during storage or processing are also discussed.     

THE CHANGING ROLE OF MILK AND MILK PRODUCTS IN DIETS IN THE UNITED KINGDOM

The paper deals with: (1) The present contribution of milk in United Kingdom diets; (2) past changes in consumption; (3) factors affecting consumption; (4) how consumption can be changed; (5) likely future changes. One difficulty is that information on consumption refers to groups; little is known about individual consumption. This is even more true for past consumption patterns. Many factors affect consumption. A major part is played by government intervention, both in regulating prices and in distribution of welfare milk. Propaganda that milk fat is harmful has had little effect in this country. Future trends are difficult to forecast since they increasingly depend on government policy.     

PROGRESS AND DEVELOPMENT OF UHT MILK AND MILK PRODUCTS IN THE UK DAIRY INDUSTRY

The paper covers the history of UHT sales in the UK and explains reasons for the small sale of UHT milk. Sales are expected to rise significantly - more sterilized milk is being replaced by UHT, and skimmed milk and flavoured milks being promoted. UHT product sales are encouraging with cream, custards, desserts and ice-cream established. With continual price increases, caterers and shops would want to reduce waste and require non-perishable goods. UHT processing could be beneficial to dairies for doorstep delivery as well as shop sales. Particular mention is made of the success dairies have had with aseptically packed juice.