Brian Nummer

Effects of preparation methods on the microbiological safety of home-dried meat jerky.

Historically, drying meats to produce jerky was conisidered to be a safe preservation process and the convenience and flavor of jerky has made it a popular food product for home food preservers. Recent outbreaks of foodborne illness related to both home-dried and commercially manufactured jerky have raised concerns about the safety of the product. Some traditional home recipes and drying processes were shown to be inadequate to destroy Escherichia coli O157, Salmonella, Staphylococcus aureus, and Listeria monocytogenes in both whole-muscle and ground-meat jerky. Several research studies have identified processes such as precooking meats before drying, usingacidic marinades, cooking meats after drying, or some combination of these treatments that can destroy pathogens of concern to produce microbiologically safe and palatable meat jerky at home.

Survival of Listeria monocytogenes introduced as a post-aging contaminant during storage of low-salt Cheddar cheese at 4, 10, and 21°C.

Traditional aged Cheddar cheese does not support Listeria monocytogenes growth and, in fact, gradual inactivation of the organism occurs during storage due to intrinsic characteristics of Cheddar cheese, such as presence of starter cultures, salt content, and acidity. However, consuming high-salt (sodium) levels is a health concern and the dairy industry is responding by creating reduced-salt cheeses. The microbiological stability of low-salt cheese has not been well documented. This study examined the survival of L. monocytogenes in low-salt compared with regular-salt Cheddar cheese at 2 pH levels stored at 4, 10, and 21°C. Cheddar cheeses were formulated at 0.7% and 1.8% NaCl (wt/wt) with both low and high pH and aged for 10 wk, resulting in 4 treatments: 0.7% NaCl and pH 5.1 (low salt and low pH); 0.7% NaCl and pH 5.5 (low salt and high pH); 1.8% NaCl and pH 5.8 (standard salt and high pH); and 1.8% NaCl and pH 5.3 (standard salt and low pH). Each treatment was comminuted and inoculated with a 5-strain cocktail of L. monocytogenes at a target level of 3.5 log cfu/g, then divided and incubated at 4, 10, and 21°C. Survival or growth of L. monocytogenes was monitored for up to 90, 90, and 30 d, respectively. Listeria monocytogenes decreased by 0.14 to 1.48 log cfu/g in all treatments. At the end of incubation at a given temperature, no significant difference existed in L. monocytogenes survival between the low and standard salt treatments at either low or high pH. Listeria monocytogenes counts decreased gradually regardless of a continuous increase in pH (end pH of 5.3 to 6.9) of low-salt treatments at all study temperatures. This study demonstrated that post-aging inoculation of L. monocytogenes into low-salt (0.7%, wt/wt) Cheddar cheeses at an initial pH of 5.1 to 5.5 does not support growth at 4, 10, and 21°C up to 90, 90, and 30 d, respectively. As none of the treatments demonstrated more than a 1.5 log reduction in L. monocytogenes counts, the need for good sanitation practices to prevent post-manufacturing cross contamination remains.

Survival of Salmonella Serovars Introduced as a Post-Aging Contaminant during Storage of Low-Salt Cheddar Cheese at 4, 10, and 21 °C

UNLABELLED The microbiological stability of low-salt cheese has not been well documented. This study examined the survival of Salmonella in low-salt compared to regular salt Cheddar cheese with 2 pH levels. Cheddar cheeses were formulated at 0.7% and 1.8% NaCl (wt/wt) with both low and high-pH and aged for 12 wk resulting in four treatments: 0.7% NaCl and pH 5.1 (low-salt and low-pH); 0.7% NaCl and pH 5.5 (low-salt and high-pH); 1.8% NaCl and pH 5.7 (standard-salt and high-pH); and 1.8% NaCl and pH 5.3 (standard-salt and low-pH). Each treatment was comminuted and inoculated with a 5-serovar cocktail of Salmonella at a target level of 4 log CFU/g, then divided and incubated at 4, 10 and 21 °C for up to 90, 90, and 30 d, respectively. Salmonella counts decreased by 2.8 to 3.9 log CFU/g in all treatments. In the initial period of survival study, standard-salt treatments exhibited significantly lower Salmonella counts compared to low-salt treatments. The pH levels did not exhibit obvious significant effect in the Salmonella survival in low-salt treatments. Salmonella counts declined gradually regardless of a continuous increase in pH (end pH of 5.3 to 5.9) of low-salt treatments at all study temperatures. Salmonella counts were reduced faster at 21 °C storage. Although there were significant reductions in Salmonella counts, the treatments demonstrated survival of Salmonella for up to 90 d when stored at 4 or 10 °C and for up to 30 d at 21 °C, the need for good sanitation practices to prevent postmanufacturing cross contamination remains. PRACTICAL APPLICATION Low-salt aged Cheddar cheese could not support the growth of inoculated Salmonella and in fact gradual reduction in Salmonella count occurred during storage. Besides being nutritionally better, low or reduced salt Cheddar are safe as their full salt counterparts and that salt may only be a minor food safety hurdle regarding the post-aging contamination and growth of Salmonella. However, the treatments could not demonstrate complete destruction of Salmonella for up to 90 d when stored at 4 or 10 °C and for up to 30 d at 21 °C, the need for good sanitation practices to prevent postmanufacturing cross-contamination remains.

Antilisterial activity of lactose monolaurate in milk, drinkable yogurt and cottage cheese

Lactose monolaurate (LML) was previously found to be an antimicrobial against Listeria monocytogenes in culture medium at concentrations between 3 and 5 mg ml−1. In this study, the microbial inhibitory activity of LML in dairy products inoculated with a 5‐strain cocktail of clinical isolates of L. monocytogenes was investigated. Addition of LML at a concentration of 5 mg ml−1 resulted in 4·4, 4·0 and 4·2 log reductions in 0·5% fat, 1% fat and 3·25% fat milks, respectively; 4·1, 4·4, and 3·5 log reductions in nonfat, 1% fat, and 1·5% fat yogurts, respectively; and 4·0 log reductions in both nonfat and 2% fat cottage cheese. The inhibitory effect of LML was only observed at 37°C and not 5°C. Experiments suggest that both the lauric acid and the esterified lactose moiety of LML play roles in the growth inhibition.

Hazard Analysis and Critical Control Points (HACCP)

Hazard analysis and critical control points, or HACCP, are a systematic, organized approach to the identification, evaluation, and control of food safety hazards (FDA 1997a). HACCP manages food safety through the analysis and control of certain hazards during all facets of the food supply chain: from the production of raw materials to handling, manufacturing, shipping/transportation, and consumption (FDA 2013a).

Microbiology ( of the Food Code )

Some microorganisms have the potential to cause disease or illness in humans and animals. Microorganisms that have the ability to cause illness are referred to as pathogens and include bacteria, viruses, parasites, and other organisms. This chapter focuses on those pathogens that are transmitted via food and includes a discussion of pathogens, foodborne diseases the pathogens cause, the foods with which pathogens are commonly associated, and the steps that can be taken to eliminate or keep the microorganisms at safe levels.

Process Optimization and Consumer Acceptability of Salted Ground Beef Patties Cooked and Held Hot in Flavored Marinade

UNLABELLED Food safety is paramount for cooking hamburger. The center must reach 71 °C (or 68 °C for 15 s) to assure destruction of E. coli O157:H7 and other food pathogens. This is difficult to achieve during grilling or frying of thick burgers without overcooking the surface. Thus, the feasibility of partially or completely cooking frozen patties in liquid (93 °C water) together with hot holding in liquid was investigated. Initial studies demonstrated that compared to frying, liquid cooking decreased (P < 0.05) patty diameter (98 compared with 93 mm) and increased (P < 0.05) thickness (18.1 compared with 15.6 mm). Liquid cooked patties had greater weight loss (P < 0.05) immediately after cooking (29 compared with 21%), but reabsorbed moisture and were not different from fried patties after 1 h hot water holding (61 °C). Protein and fat content were not affected by cooking method. However, liquid cooked patties were rated lower (P < 0.05) than fried patties for appearance (5.7 compared with 7.5) and flavor (5.9 compared with 7.5). An 8-member focus group then evaluated methods to improve both appearance and flavor. Salted, grill-marked patties were preferred, and caramel coloring was needed in the marinade to obtain acceptable flavor and color during liquid cooking or hot holding. Patties with 0.75% salt that were grill-marked and then finish-cooked in hot marinade (0.75% salt, 0.3% caramel color) were rated acceptable (P < 0.05) by consumers for up to 4 h hot holding in marinade, with mean hedonic panel ratings > 7.0 (like moderately) for appearance, juiciness, flavor, and texture. PRACTICAL APPLICATION Grill-marked and marinade-cooked ground beef patties reached a safe internal cooking temperature without overcooking the surface. Burgers cooked using this method maintained high consumer acceptability right after cooking and for up to 4 h of hot holding. Consumers and foodservice operations could use this method without specialized equipment, and instead use inexpensive and common equipment such as a soup pot or a restaurant steam table. Use of marinades (salt/caramel color or others) in this cooking and holding method provides a nearly endless culinary flavoring opportunity.

Hand Safety for Specialty Crop Production Workers – Frequencies of Open Wound Hand Injuries

The objective of this study was to identify minor open-wound hand injuries of farm workers who hand harvest fresh fruits in Utah. During on-site data collection during harvesting of fruit, farm workers were asked to have their hands examined for minor open-wounds. Data collection was conducted on four farms. There were 33 workers that participated. The majority (57.6%) of farm workers were male. Most farm workers (81.8%) identified themselves as Latino or Hispanic. There were six (18%) individual who identified themselves as Thai. There were eight (24%) farm workers who had cuts to the dorsal portion of their hands. Only two (6%) individuals had cuts to the palm potion of their hands. There were four (12%) workers with dorsal abrasions located near the base of the hand near the wrist, while only one (3%) individual was identified with a palm abrasion. Only two (6%) farm workers were found with small puncture wounds to one of their fingers. There were two (6%) individuals that were noted with fingernail loss. This study has identified essential safety issues that need to be addressed for improving the effectiveness of safety training for migrant farm laborers. These open wound injuries to Migrant Hispanic farm workers during hand harvesting could create additional health problems with the possibility of infection and the spread of diseases such as hepatitis A. Continued research is need to understand workers’ acceptance of these injuries and barriers to personal protection.