A RESEARCH NOTE: DETECTION OF ADULTERATION IN PROCESSED TRADITIONAL MEAT PRODUCTS

Nondeclared protein addition is one of the most frequent adulterations used in meat products. Meat substitution with an unspecified specie, usually of less quality, is a fraudulent act in the industry and could have economic and health repercussions. In this study, we used an immunodiffusion assay in agar gel to identify bovine, porcine, equine and avion species in two slightly processed meat products, uncooked commercial hamburger and Mexican sausage (chorizo). Analysis of 40 samples from local food stores was performed. Undeclared equine specie was detected in 9 of the 23 of the hamburger meat samples. In Mexican sausage undeclared equine and porcine specie were also found in 5 of the 17 samples. These results showed violations in practices of the regional meat industry. It is suggested that regulatory agencies institute programs to ensure that meat products are properly labeled to protect consumers.     

RAPID METHOD FOR DETECTION OF SALMONELLAE ATTACHED TO CHICKEN SKIN1

A rapid, sensitive nitrocellulose membrane lifting technique was developed to identify Salmonella typhimurium attached to chicken skin. Basically, this method used a nitrocellulose membrane to remove salmonellae attached to chicken skin. The membrane with attached salmonellae was then incubated on xylose lysine deoxycholate (XLD) agar for 18 h at 37°C. Appearance of black colonies on the white membrane was considered a positive presumptive test for salmonellae. Immunostaining of colonies on the nitrocellulose membrane was then used to confirm presence or absence of salmonellae. This technique can be used to identify salmonellae contamination of chicken skin in less than 24 h and was shown to be more sensitive than presently used swabbing or washing techniques.     

A SIMPLE,RAPID METHOD FOR THE DETECTION OF SUBSPECIES OF ZYMOMONAS MOBILIS

Zymomonas strains are simply and rapidly detected after growth in a selective liquid medium by the addition of a Schiff's reagent. This dye reacts with acetaldehyde produced by Zymomonas to give a deep purple colour. The optimal conditions for the test are evaluated and it is shown to be specific for Zymomonas strains. The use of the dye reaction in routine microbiological quality control is described. A comparison is presented of the dye test and the use of an agar medium containing sulphite and lead acetate on which Zymomonas strains which produce H₂S form characteristic colonies.     

RAPID METHODS FOR THE DETECTION OF YEAST AND LACTOBACILLUS BY ATP BIOLUMINESCENCE

Present plating methods for the detection of potential spoilage organisms in packaged beers require 2–3 days for yeast, and 5–7 days for lactic acid bacteria. Simple and inexpensive sterility tests based on bioluminescence have been developed for the detection in broth media of small numbers of yeasts in 1 day, and lactic acid bacteria, in both normal and heat-stressed conditions, in 3 days.     

INACTIVATION OF SHEWANELLA PUTREFACIENS BY GAMMA IRRADIATION OF RED MEAT AND POULTRY

The resistance of Shewanella putrefaciens ATCC 8071, 8072, and 8073 to gamma radiation was determined in the presence and absence of air on mechanically deboned chicken meat (MDCM). The presence or absence of air (oxygen) did not significantly influence resistance to gamma radiation at 5C, and it was very sensitive with a D₁₀ value of 0.11 ± 0.002 kilogray (kGy) on MDCM. A high percentage of cells surviving irradiation were shown by impedance measurements to have suffered injury. The bacteria were significantly more resistant to gamma radiation at temperatures below the freezing point. At a dose of 0.8 kGy lowering the temperature of irradiation by 10 degrees increased the survival of this food spoilage organism by a 1.66 log₁₀. The type of meat (hamburger, ground beef round, ground pork, and ground turkey breast) did not significantly alter resistance of S. putrefaciens to gamma radiation under identical conditions (D₁₀ value = 0.18 ± 0.01 kGy). The minimum radiation dose currently approved for poultry in the USA, 1.5 kGy, should eliminate S. putrefaciens from meats.     

PSYCHROTROPHIC AND MESOPHILIC FUNGI ISOLATED FROM IMPORTED FROZEN LEAN MEAT IN EGYPT

From 475 samples of imported frozen lean beef in Egypt, 859 psychrotrophic fungal strains (770 strains by the dilution plating and 89 strains by direct plating) were isolated. There were also 1291 mesophilic fungal strains isolated (1133 and 158 strains by the two different methods, respectively). The predominant psychrotrophs identified were species of Cladosporium and Penicillium while most mesophiles were in the genera of Aspergillus, Cladosporium and Penicillium.     

生活饮用水和肉制品中亚硝酸盐的快速测定

实验建立了一种简便、快速测定亚硝酸盐含量的新方法。在这种方法中，NO2^-与对氨基苯磺酸发生重氮化反应，将反应液缓慢倒入由吸附1-萘酚的D290树脂填充的吸附柱中生成红色的偶氮染料。亚硝酸盐测定的线性范围为0．1μg／mL～10.0μg／mL，检出限为0．1μg／mL。将显色结果与标准比色卡比对可进行生活饮用水和肉制品中亚硝酸盐含量的定性和半定量分析，结果满意。     

DETECTION OF BIOGENIC AMINES AS MEAT SPOILAGE INDICATORS

Preparative ion exchange chromatography was performed on beef and pork samples stored at 4–6°C and wrapped in commercial film (Saran). Different peaks obtained for the two species studied, were attributable to the different type of biogenic diamines produced during spoilage. A second set of experiments was performed with pork, beef and rabbit samples. The last served as a control, since no record was available for the time elapsed since slaughtering of the animals of the other two species. Analyses were performed to determine total amine nitrogen produced during storage at chill temperatures in wrapped and unwrapped samples, and the amount of Pseudomonas , total aerobic organisms and lactic acid bacteria. Results suggested that the wrapping material did not produce the microaerophilic conditions to promote the growth of required lactic acid bacteria sufficient to outnumber the other microorganisms present. However, diamine production was slower in wrapped than in unwrapped samples.     

THE RAPID DETECTION OF BREWERY SPOILAGE MICRO-ORGANISMS

Recent developments in the rapid detection of low concentrations of micro-organisms are discussed and their relevance to improved brewery quality control methods is assessed. A method based on the change in pH of a general purpose growth medium appears to offer the advantages of both time and sensitivity over methods currently in use.