Nathan Jarvis

Whole-chain traceability, is it possible to trace your hamburger to a particular steer, a U. S. perspective

Traceability through the entire food supply chain from conception to consumption is a pressing need for the food industry, consumers and government regulators. A robust, whole-chain traceability system is needed that will effectively address food quality, food safety and food defense issues by providing real-time, transparent and reliable information from beef production through slaughter and distribution to the consumer. Traceability is an expanding part of the food safety continuum that minimizes the risk of foodborne diseases, assures quality and cold-chain integrity. Traceability can be a positive competitive marketing edge for beef producers who can verify specific quality attributes such as humane production or grass fed or Certified Organic. In this review we address the benefits as well as the remaining issues for whole-chain traceability in the beef industry, with particular focus on ground beef for the markets in the United States.

The Potential Link between Thermal Resistance and Virulence in Salmonella: A Review

In some animals, the typical body temperature can be higher than humans, for example, 42°C in poultry and 40°C in rabbits which can be a potential thermal stress challenge for pathogens. Even in animals with lower body temperatures, when infection occurs, the immune system may increase body temperature to reduce the chance of survival for pathogens. However, some pathogens can still easily overcome higher body temperatures and/or rise in body temperatures through expression of stress response mechanisms. Salmonella is the causative agent of one of the most prevalent foodborne illnesses, salmonellosis, and can readily survive over a wide range of temperatures due to the efficient expression of the heat (thermal) stress response. Therefore, thermal resistance mechanisms can provide cross protection against other stresses including the non-specific host defenses found within the human body thus increasing pathogenic potential. Understanding the molecular mechanisms associated with thermal responses in Salmonella is crucial in designing and developing more effective or new treatments for reducing and eliminating infection caused by Salmonella that have survived heat stress. In this review, Salmonella thermal resistance is assessed followed by an overview of the thermal stress responses with a focus on gene regulation by sigma factors, heat shock proteins, along with the corresponding thermosensors and their association with virulence expression including a focus on a potential link between heat resistance and potential for infection.

Development of an Augmented Reality Game to Teach Abstract Concepts in Food Chemistry

One of the most pressing issues for many land grant institutions is the ever increasing cost to build and operate wet chemistry laboratories. A partial solution is to develop computer-based teaching modules that take advantage of animation, web-based or off-campus learning experiences directed at engaging students’ creative experiences. We used the learning objectives of one of the most difficult topics in food chemistry, enzyme kinetics, to test this concept. Students are apprehensive of this subject and often criticize the staid instructional methods typically used in teaching this material. As a result, students do not acquire a useful background in this important subject. To rectify these issues, we developed an interactive augmented reality application to teach the basic concepts of enzyme kinetics in the context of an interactive search that took students to several locations on campus where they were able to gather raw materials and view videos that taught the basics of enzyme kinetics as applied to the production of high fructose corn syrup (HFCS). The students needed this background to prepare for a mock interview with an HFCS manufacturer. Students and instructors alike found the game to be preferable to sitting in a classroom listening to, or giving, a PowerPoint presentation. We feel that this use of gaming technology to teach difficult, abstract concepts may be a breakthrough in food science education and help alleviate the drain on administrative budgets from multiple wet labs.

Listeria monocytogenes Infection of HD11, Chicken Macrophage-Like Cells

&NA; Listeria monocytogenes can be carried by and infect poultry, although the clinical disease in birds is rare. Escape from macrophage phagocytosis is a key step in pathogenesis for L. monocytogenes. Therefore, we investigated the infection of the chicken macrophage‐like cell line HD11 with 2 strains of L. monocytogenes EGD‐e and Scott A. After infection, L. monocytogenes was quantified by spread plating and HD11 was quantified with trypan blue exclusion stain before enumeration. The standard macrophage killing protocols require washing the cell monolayers 3 times with PBS, which was found to negatively influence HD11 monolayers. Maximum bacterial densities within macrophages were not different between the 2 Listeria strains. HD11 required more than 11 h to effectively reduce intracellular L. monocytogenes Scott A, and Scott A was more susceptible to HD11 killing than EGD‐e. It appears that Listeria infection initially causes attenuation of HD11 growth, and infected HD11 cells do not begin to lyse until at least 11 h post infection. These results suggest that there are subtle strain to strain differences in response to HD11 macrophage phagocytosis. The long lead‐time required for HD11 to kill L. monocytogenes cells means that there is sufficient time available for chicken macrophages to circulate in the blood and transfer the intracellular Listeria to multiple tissues.

A Comparison of the Degree of Student Satisfaction Using a Simulation or a Traditional Wet Lab to Teach Physical Properties of Ice

It is often difficult to offer food chemistry students traditional, hands-on laboratory experiences due to lack of funds for equipment, insufficient laboratory space, or the nature of distance education. A traditional wet laboratory exercise was developed to demonstrate the effects of the physical properties of ice formation when making high-quality sorbets, varying the amounts of sugar, water, and stabilizer. This wet lab was compared to a simulated, detective-based crime scene investigation (CSI) of why a famous food scientists sorbet had become a “stiff.” Forty-six food chemistry students were randomly assigned to groups, completing either the traditional wet lab or the simulated lab 1st before completing the 2nd type of laboratory. While there were preferences for one lab over another, there were no differences in the learning outcomes between the 2 laboratory formats. Students who preferred the simulated lab felt they could move at their own pace and were able to stop and review the simulation to understand the concepts more clearly. Traditional wet lab proponents liked working in groups and having immediate access to instructors. From the initial evaluation it appears that simulations could be used as replacements for hands-on laboratory experiences or could serve as effective introductions to laboratory principles and concepts, resulting in increased student learning.

The functionality of plum ingredients in meat products: a review.

Dried plums (prunes) have been marketed to consumers for consumption directly from the package as a convenient snack and have been reported to have broad health benefits. Only recently have fractionated, dried plum ingredients been investigated for their functionality in food and feed products. Dried plum puree, dried plum fiber, dried plum powder, dried plum concentrate, and fresh plum concentrate have been investigated to date. They have been evaluated as fat replacers in baked goods, antioxidants in meat formulations, phosphate replacers in chicken marinades, and antimicrobials in food systems. Overall, dried plum products have been shown to be effective at reducing lipid oxidation and show promise as antimicrobials.

Antimicrobial Resistance in Listeria spp.

Listeria monocytogenes causes a disease which particularly afflicts immune-compromised people and can result in death rates of over 30%. Most difficulty in prescribing antimicrobials for listeriosis is due to difficulty in diagnosis the illness; once properly and timely diagnosed, combinations of antimicrobials are easily provided to eliminate the infection. L. monocytogenes possesses numerous genes which confer innate resistance to some antimicrobials, particularly cephalosporins. In addition, some cell wall acting gene products increase resistance to some β-lactams and lantibiotics. Acquired resistance to some antimicrobials via transposons and plasmids is possible, but rarely to those important for treating listeriosis.

Further Evidence of How Unbuffered Starvation at 4°C Influences Listeria monocytogenes EGD-e, HCC23, F2365, and Scott A

The soilborne pathogen Listeria monocytogenes frequently contaminates food products and food processing environments and is able to survive desiccation, high osmotic pressures, and starvation. However, little is known about how this pathogen survives starvation at 4°C. This study provides evidence that L. monocytogenes is able to survive total nutrient starvation for 4 weeks. L. monocytogenes strains EGD-e, Scott A, F2365, and HCC23 were starved individually in sterile water. Colony counts declined over 4 weeks, with Scott A declining the most rapidly. Transmission electron microscopy images revealed degradation of starving cell membranes and altered cytosols. Starving cells were subjected to the metabolic inhibitors fluoride, arsenite, 2,4-dinitrophenol, iodoacetate, and cyanide individually. Iodoacetate, which inhibits glyceraldehyde-3-phosphate dehydrogenase, completely reduced cultivable counts below the level of detection compared with the control starving cells; 2,4-dinitrophenol, which dissipates proton motive force, almost completely reduced cultivable counts. These results suggest that L. monocytogenes strains EGD-e, Scott A, F2365, and HCC23 are actively using part of the glycolysis pathway while starving. These results suggest that starving L. monocytogenes cells retain aspects of active metabolism.

Student-Centered and Dynamic Interfaces that Enrich Technical Learning for Online Science Learners: A Review of the Literature

Communicating complex scientific and technical information presents a challenge for food science educators. The most efficient learning occurs when all senses are engaged, one reason that many educators believe that scientific principles are best taught with hands-on laboratory experiences. Today there are many challenges to the continuation of these “wet labs” including the cost of building the labs as well as equipment, materials, and personnel to run them. Many current e-learning technologies are based on 2-dimensional delivery systems, and are often inadequate to provide a substitute for a laboratory exercise. However, recent advances in technology have evolved to more closely reflect the kinds of learning experiences that students typically have in a laboratory class. This review describes the role of these emerging technologies as teaching tools for educators, with the clear understanding that similar concepts can be utilized by management of technical teams in the work place.