Effect of microorganism characteristics on leak size critical to predicting package sterility.

The effects of microorganism size and motility on the leak size critical to the sterility of a package, along with the imposed pressure required to initiate liquid flow for the critical leak size, were measured. Pseudomonas fragi Lacy-1052, Bacillus atrophaeus ATCC 49337, and Enterobacter aerogenes ATCC 29007 were employed to assess package sterility. One hundred twenty-six 7-mm-long microtubes with interior diameters of 5, 10, and 20 microm were used to simulate package defects.

Effect of organic acids and hydrogen peroxide on Cryptosporidium parvum viability in fruit juices.

Cryptosporidium parvum has historically been associated with waterborne outbreaks of diarrheal illness. Foodborne cryptosporidiosis has been associated with unpasteurized apple cider. Infectious oocysts are shed in the feces of common ruminants like cattle and deer in and near orchards.

Comparative study of a semisynthetic derivative of natamycin and the parent antibiotic on the spoilage of shredded cheddar cheese.

A water-soluble N-alkyl semisynthetic derivative of natamycin was synthesized by the Michael addition reaction of the parent with an N-substituted malemide. A comparative study was carried out to investigate the effectiveness of the semisynthetic derivative and the parent antibiotic in suppressing mold growth on shredded Cheddar cheese stored in modified atmosphere packaging (MAP). The effects of 0-, 10-, and 20-ppm antimycotic treatments were examined.

Application of fluid modeling to determine threshold leak size for liquid foods.

In this study, the mechanism by which a package defect converts to a leaker was examined in an effort to develop a relationship between threshold leak size and loss of package sterility. The threshold leak size is the hole size at which the onset of leakage occurs. The threshold pressure is the pressure required to initiate a leak.

Examination of attachment and survival of Toxoplasma gondii oocysts on raspberries and blueberries.

The consumption of Toxoplasma gondii oocysts on fresh produce may be a means of its transmission to humans. Cats shed T. gondii oocysts, which contaminate produce directly or contaminate water sources for agricultural irrigation and pesticide and fertilizer applications.

Contamination of Flexible Pouches Challenged by Immersion Biotesting .

Immersion biotesting has long been used to challenge packages, particularly cans, for pinholes and channel leaks. Such testing for all types of plastic packaging may not be appropriate because some packages (e.g.

Bioaerosol Exposure Method for Package Integrity Testing .

Test organism motility, concentration, aerosol exposure time, hole diameter and length were evaluated to determine their influence on microbial ingress into a flexible plastic pouch. Microtubes with 10- and 20μm hole diameters and of 5- and 10-mm lengths were used as defects in 128 flexible pouches. A bioaerosol with a 2.

Predictive Model with Improved Statistical Analysis of Interactive Factors Affecting the Growth of Staphylococcus aureus 196E.

The growth of pathogenic bacteria in foods is affected by several factors which may interact to enhance or inhibit microbial growth. A model to predict the growth of Staphylococcus aureus 196E in microbiological media was developed using a modified Gompertz function and response-surface methodology. The predictive equation required the estimation of 23 parameters which describe singular and interactive effects of the growth factors studied.

Improved Recovery of Stressed Bifidobacterium from Water and Frozen Yogurt.

A roll-tube repair-detection procedure was developed to enumerate injured and noninjured cells of Bifidobacterium species from water and food samples. This procedure combined the Virginia Polytechnic Institute and State University's anaerobic roll-tube procedure and the repair-detection technique for detecting stressed cells. Mara and Oragui's human bifid sorbitol agar medium was modified for use in the roll-tube procedure by replacing the indicator bromocresol purple with phenyl red (0.

Low Temperature Growth and Thermal Inactivation of Listeria monocytogenes in Precooked Crawfish Tail Meat .

Growth of Listeria monocytogenes in precooked crawfish tail meat at 0, 6, and 12°C was determined. Thermal death times were also determined. Growth curves for L.

Seasonal Variation in the Fecal Coliform Population of Louisiana Oysters and its Relationship to Microbiological Quality.

Seasonal variation was observed in the type of bacteria which comprised the fecal coliform population of oysters. Escherichia coli was the principal fecal coliform when water temperatures were below 22°C. Conversely, Klebsiella sp.

Detection of Enteroviruses and Bacterial Indicators and Pathogens in Louisiana Oysters and Their Overlying Waters.

Field studies were conducted for 1 year to determine levels of enteroviruses in Louisiana Gulf Coast oysters and their overlying waters. Levels of human enteric viruses were compared with bacterial pathogens ( Salmonella and Vibrio parahaemolyticus ), fecal coliform levels, and physicochemical water parameters (pH, salinity, temperature, and conductivity). Samples of 20-30 oysters and 380 L of overlying water were collected monthly from both "open" and "closed" oyster growing areas.

Evaluation of Methods for Extraction of Enteric Virus from Louisiana Oysters.

Six techniques were evaluated for recovery of poliovirus from Louisiana oysters. The methods were compared for percent recovery rates, toxicity, ease of extraction, bacterial contamination, and final volume of oyster concentrate. Oyster samples were contaminated with 30-40 plaque forming units of Poliovirus type 1 and processed by six variations of adsorption-elution-precipitation and elution-precipitation methods.

Enteric Bacterial and Viral Pathogens and Indicator Bacteria in Hard Shell Clams.

Enteric bacteria and virus levels were determined in hard shell clams, Mercenaria mercenaria , harvested from areas open or closed for commercial shellfishing on the basis of total coliform levels in water. Four pairs of open and closed stations were sampled seasonally over a 1-year period. Enteric viruses were isolated from 3 of 13 100-g clam samples from open beds and 6 of 15 samples from closed beds.

Occurrence of Enteric Bacteria and Viruses in Oysters.

Enteric bacteria and virus levels were determined in oysters from paired stations that were opened or closed for commercial shellfishing on the basis of total coliform levels in the water. Six pairs of stations were sampled quarterly over a 1-year period. Enteric viruses were found in 3 of 24 50-g oyster samples from closed areas and in none of 23 samples from open areas.