SURVIVAL OF CAMPYLOBACTER JEJUNI IN MARINATED AND NONMARINATED CHICKEN PRODUCTS

Consumption of chicken products has been increasing. Most of these products in Finland are sold as fresh marinated pieces in consumer packages. The impact of marination on the survival of enteric pathogens is not known. We studied the survival of Campylobacter jejuni on marinated chicken drumsticks and sliced breast strips stored at a refrigerator temperature of +4C. The marinade was an emulsion of vegetable oil and water with spices, NaCl (5.9% wt/wt) and its pH was adjusted to 4.5 with lactic and acetic acid. The survival of C. jejuni was similar in marinated and nonmarinated chicken drumsticks and strips. The organisms were detected for at least nine days at the higher inoculum level (10¹– 10² CFU/mL) and for at least five days at the lower inoculum level (10¹– 10² CFU/mL). C. jejuni, inoculated into plain marinade and stored at 4C, was detected after 24 h but not after 48 h. Our results revealed that marination procedure used to reduce and prevent the growth of spoilage organisms does not significantly decrease the survival of Campylobacter jejuni in chicken products.     

IN VITRO SURVIVAL AT LOW pH AND ACID ADAPTATION RESPONSE OF CAMPYLOBACTER JEJUNI AND CAMPYLOBACTER COLI

The survival of Campylobacter jejuni and Campylobacter coli at pH 7.0, 6.0, 5.0 and 4.0 for up to 24 h, and the induction of an acid adaptation response in 12 C. jejuni and 10 C. coli strains in early exponential or late stationary phases in tryptic soy broth (TSB) and Brucella broth were investigated. C. coli strains were more sensitive than C. jejuni in media adjusted to pH 5.0 or 4.0 with hydrochloric acid. Five log₁₀ cfu/mL of C. coli were inhibited at 12 h in pH 5.0, but only 2.5 log₁₀ cfu/mL of C. jejuni cells were inhibited under the same conditions. No viable cells were detected at 4 h in pH 4.0 from an inoculum of 6 log₁₀ cfu/mL of C. coli. Late stationary phase cells of C. jejuni exposed to pH 5.0 for 4 h in TSB exhibited a significant (P ≤ 0.05) acid tolerance response when compared to nonexposed cells. Late stationary phase cells of C. coli exposed to pH 5.0 for 3 h in TSB and late stationary and early exponential phase cells exposed to pH 5.0 for 3 h in Brucella broth showed a significant (P ≤ 0.05) acid tolerance response when compared to nonexposed cells. The acid tolerance responses observed for C. jejuni and C. coli conferred adapted cells no more than 1 log₁₀ cfu/mL survival advantage over nonadapted cells. Brucella broth appeared to be more protective than TSB for the survival of C. jejuni and C. coli at pH 4.0.     

EFFECT OF VACUUM PACKAGING ON CHANGES ASSOCIATED WITH FROZEN COD FILLETS

Protein solubility of cod fillets sealed under vacuum was significantly higher at all sampling times than from fillets sealed in presence of air during an 18 months storage study at −25°C. Frozen storage resulted in substantial loss of protein from all of the bands of the PAGE pattern, with more pronounced loss from the myosin heavy chain, actin and tropomyosin bands. Dimethylamine and malonaldehyde concentrations were not significantly different between the air and vacuum pack. Significant losses in flavor and textural quality during frozen storage were detected. Crosslinking, responsible for the observed reduction in protein solubility of raw tissue, appears to be of relatively weak nature, since little toughening was detected in the cooked tissue.     

ACIDIFIED SODIUM CHLORITE, TRISODIUM PHOSPHATE AND POPULATIONS OF CAMPYLOBACTER JEJUNI ON CHICKEN BREAST SKIN

The present study was designed to determine the effects of acidified sodium chlorite (ASC) and trisodium phosphate (TSP) antimicrobial treatments. Chicken skin samples inoculated with Campylobacter jejuni ATCC 33291 and C. jejuni pc10 (isolated in our laboratory from chicken carcasses) were separately dipped into sterile tap water (control), 0.1% ASC, 10% TSP, 0.1% ASC followed by 10% TSP and 10% TSP followed by 0.1% ASC for 15 s at 25 ± 1C. Campylobacter jejuni counts and pH values were determined after 0, 1, 3 and 5 days of storage at 4 ± 1C. On day 0, reductions were between 1.1–2.5 log for C. jejuni ATCC 33291 and 1.4–2.4 log for C. jejuni pc10, while the reduction effects of all antimicrobials increased (P < 0.001) during the storage period and the bacterial counts reached undetectable levels (<1.0 × 10² cfu/g) on day 5 of storage at 4 ± 1C. The results of this study suggest that introduction of the antimicrobial treatments ASC, TSP and ASC followed by TSP into poultry processing systems could provide an added measure of safety.     

SELECTIVITY AND SENSITIVITY OF THREE MEDIA FOR RECOVERY OF INOCULATED CAMPYLOBACTER FETUS SSP. JEJUNI FROM GROUND BEEF1

Modified Skirrow's (with 15 μg cephalothin/ml), Campy-BAP, and Butzler's selective agar plates were compared for sensitivity and selectivity in the recovery of inoculated Campylobacter fetus ssp. jejuni from ground beef. The diluted inoculation samples were surface plated directly onto these selective plates and incubated. When colonies on the plates were enumerated, characterized, and identified, Campy-BAP medium proved to be the most sensitive for recovery, and Butzler's medium the most selective. Contaminants of Pseudomonas and Acinetobacter were observed. A combination of both Campy-BAP and Butzler's media should prove most useful in the recovery of Campylobacter from food sources. The significance of current taxo-nomical considerations for food microbiologists are also discussed.     

ENZYMATIC AND SOME BIOCHEMICAL CHANGES ASSOCIATED WITH THE PRODUCTION OF "KANTONG," A TRADITIONAL FERMENTED CONDIMENT IN NORTHERN GHANA

This paper reports on the activities of three major food enzymes (amylase, protease and lipase) during the traditional fermentation of Ceiba pentandra seeds into "kantong," a condiment used in Northern Ghana for soups. Samples were taken at periodic intervals during the fermentation, and enzyme activities and other parameters were determined. All enzyme activities increased steadily during fermentation, but leveled off when the fermentation was stopped at 48 h and the product dried. The increase in enzyme activities led to significant reductions in the levels of fiber and lipids, whereas protein and ash contents increased significantly ( P <  0.05). The fermentation produced significant increases in the concentration of all the amino acids. The process was acidic, as the pH dropped from 6.95 to 4.91. "Kantong," used in poor homes as substitute for meat or fish for flavoring soups, can serve as a nutritious condiment in the diet and its consumption should be encouraged.

PRACTICAL APPLICATIONS

"Kantong" is a traditional fermented condiment produced by the fermentation of the seeds of silk cotton (Ceiba pentandra). It is widely used in Northern Ghana as flavoring for soups and stews. However, no scientific studies about the fermentation process have been carried out. A scientific understanding of the fermentation process will enable a technological improvement on the process, either by the use of starter cultures or the addition of exogenous enzymes to the medium for the substrate conversion. The work also provided information on the nutritional value of the product, and thus its role in providing food security to the people who use it. The microbiological aspects of the fermentation are described under a different topic.     

EVALUATION OF ATTACHMENT AND PENETRATION ABILITIES OF CAMPYLOBACTER JEJUNI ISOLATES OBTAINED FROM HUMANS AND CHICKEN CARCASSES DURING PROCESSING AND AT RETAIL

The differences in attachment and penetration ability of Campylobacter jejuni were determined by analyzing C. jejuni isolates obtained from chicken carcasses and from humans exhibiting symptoms of campylobacteriosis. INT 407 cells, a human cell line originating from the jejunal/ileal region, were used as the in vitro model, and attachment and penetration abilities were evaluated for each isolate. There were no significant differences between the attachment and penetration abilities of chicken isolates and human isolates (HUMN). In addition, a wide range of attachment and penetration abilities was found for the isolates, with many of the HUMN possessing low attachment and penetration abilities. These data indicate that C. jejuni attachment and penetration into the human ileal and jejunal regions may not be primary virulence factors and may only be important in causing more acute symptoms.     

VARIATION IN STIMULI ASSOCIATED WITH ORAL EVALUATION OF THE VISCOSITIES OF GLUCOSE SOLUTIONS

Abstract. Previous observations suggesting that different stimuli are associated with oral evaluation of the viscosity of fluid and of viscous foods have been confirmed. The change in stimuli begins at a viscosity of about 70 cp. In the initial study sensory evaluation of viscosity was by paired comparisons, while in this study distance measures and ratio scaling were used. The agreement between the data indicates that the observations are independent of the evaluation procedure employed.