Performing Department
Food Science & Technology
Non Technical Summary
Current estimates coming from The Centers for Disease Control and Prevention (CDC) show that 48 million Americans are inflicted with foodborne illnesses annually. This results in an approximation of 128,000 hospitalizations and 3,000 deaths. Although this number is of concern in any advanced modern country, it is a reduction in the numbers of outbreaks and illnesses reported by CDC in its 1999 estimates. However, these current estimates still show that outbreaks continue to be associated with selected "high risk" foods that are susceptible to contamination by pathogens such as human norovirus (NoV), hepatitis E virus (HEV), Salmonella, Listeria, E. coli and Campylobacter, etc. Outbreaks caused by these and other organisms have resulted in severe economic losses to the US economy as well as becoming a significant health burden on the population.To address this issue, several hurdle technologies have been proposed. Many of them are reported in the literature, and they include emerging non-thermal technologies such irradiation (including ultra violet, gamma, e-beam, and infra-red) high pressure, magnetism, pulse light and pulse electric fields, plus novel thermal techniques such as ohmic and microwave heating. In addition to these, chemical approaches to control the survival of microorganisms in food include the use of antibiotics, and other chemical sterilants and sanitizers. In some cases, biological approaches have been attempted. Irrespective of these various intervention methods, the problem of food contamination and subsequent outbreaks seem to continue unabated. However, for the survival of our modern way of life, it is essential that the war against microbial contamination and foodborne outbreaks must continue, and that newer and more advanced technologies be used in this fight.Almost all foods marketed in the United States are packaged in one form or another. Packaging serves various important functions, including protection, communication, convenience, transportation and the preservation of foods. In order to ensure the safety and long term shelf life of many processed foods, packaging has become an essential component of this formula. To accomplish this, two general types of packaging have emerged. The first one is natural and the second is artificial packaging. Examples of natural packaging include egg shells and the skins of plants (including fruits and vegetables) and animals. Artificial packaging are typically made from glass, metal, plastics and paper, and in some cases a combination of these materials (called composite materials). Materials used to make artificial packaging can either be of synthetic or natural origin. Natural materials include items such as starches, proteins and lipids, referred to as edible packaging, or non-edible materials such as wood, leaves and stems. In many instances a combination of natural and synthetic packaging types are necessary for the extended shelf life of certain foods.Since packaging is essential to the shelf life of foods, especially processed foods. The use of packaging as a tool for intervention technologies is increasing being used by the food and pharmaceutical industries for shelf life extension. Examples of this can be seen in technologies such as active packaging, modified atmosphere packaging, control atmosphere packaging, and in most recent times as "smart packaging." Examples of active packaging include antimicrobial, antioxidant, gas permeation controllers, odor, ethylene and moisture absorbing, and flavor releasing materials. Of all these technologies, the one that is least developed and commercialized is antimicrobial packaging, although the literature reports many studies done to justify its viability. As a result, this project will focus on the development of antimicrobial packaging materials using natural compounds with efficacy against known pathogens of public health concerns. The use of natural compounds was chosen because current consumers' trends indicate that people are increasing becoming concern about the use of synthetic chemicals in processed foods (Larotonda et al., 2005; Siracusa et al., 2008; Janjarasskul and Krochta, 2010). This has given rise to the use of the words "clean labels" in food marketing circles.
Animal Health Component
0%
Research Effort Categories
Basic
40%
Applied
50%
Developmental
10%
Goals / Objectives
The main objective of this study is to develop antimicrobial materials for food packaging applications. The specific objectives are:To incorporate natural antimicrobial compounds into natural packaging materials used for food packaging.Optimizing the concentration of the compounds for microbial control in selected foodsTo ensure that the added ingredients do not negatively impact the mechanical, thermal and physical properties of the materials.
Project Methods
Natural films formationThe films that will be studies are tapioca starch and whey protein isolate. Tapioca starch powder will be purchased from a local supermarket in Columbus, Ohio. It will be irradiated at the Nuclear Reactor Laboratory located at The Ohio State University (OSU), in order to achieve sterilization. Distilled water will be used to make a suspension of the starch powder. Glycerol ≥99.0% (Sigma-Aldrich®) will be used as a plasticizer and acetic Acid (ACS Reagent ≥99.7%) and Dimethyl Sulfoxide (DMSO) (ACS Reagent ≥99.9%) will be used as solvents. The natural antimicrobial compounds will be ones that were synthesized at OSU and are referred to as small molecules. Three of these compounds, referred to as JA-144, TH-4 and TH-8 were obtained from Dr. James Fuch's laboratory at the College of Pharmacy, OSU. Compounds JA-144, TH-4 and TH-8 were derived from primary compounds that were identified as anti-Campylobacter agents. These compounds are isomers of metabolites normally produced by these organisms when they are exposed to toxic chemicals in their external environment. The main reason for selecting these class of compounds is the fact that the organisms are not expected to develop antimicrobial resistance to them, since they are normally produced by the bacteria. At the same time, preliminary studies showed that these compounds exhibited antimicrobial properties to a wide variety of bacterial species at concentrations that were not toxic to humans and animals. These agents were selected after a high throughput screening of a library of ~4,200 compounds (Kumar et al., 2016).Antimicrobial properties testing Minimum Inhibitory Concentrations (MIC) for JA-144, TH-4 and TH-8 against E. coli K12, L. innocua, C. jejuni and C. coli in Mueller-Hinton broth (MHB) at 37oC will be determined. The range of concentrations for the small molecules in the films depends on previous cytotoxicity assay conducted by Dr. Esperanza Carcache de Blanco's laboratory in the College of Pharmacy at OSU. This test determined the highest concentrations of the compounds to cause lysis of human colon cells. As a results, this study will test JA-144, TH-4 and TH-8 at 66.9 ppm, 61.1 ppm, 60.4 ppm, respectively. A sterile 96 well plate will be used for the MIC tests. A positive control will be used and will be made of 198.6μl of MHB with E. coli K12, L. innocua, C. jejuni, and C. coli at a concentration of 106 CFU/ml, 0.4μl of Chloramphenicol (2μl/ml in broth), and 1μl TTC stock solution (100ppm in broth). This will be pipetted into the first column of the plate. The MIC test groups will be placed in row 2 to row 11, plus 197μl of MHB inoculated with E. coli K12, L. innocua, C. jejuni, or C. coli at 106 CFU/ml, and 2μl of DMSO with diluted JA-144, TH-4 or TH-8, and 1ul TTC stock solution. A negative control group will be prepared by repeating the above, but without JA-144, TH-4 or TH-8. This negative control group will be pipetted into the last column of the plate. From the data collected, microbial growth curves will be prepared. This test will be repeated with the antimicrobial compounds incorporated into the tapioca and whey protein isolate films. This will allow for the efficacy testing of the compounds when in the films as antimicrobial agents.Functional groups characterizationDifferential scanning calorimetric (DSC) analysis Thermal stability of the films will be evaluated using a 2920 Modulated DSC with Universal Analysis software package v.3.9a (TA Instrument Corp. New Castle, Delaware). The film samples (11± 0.2 mg) will be placed into stainless steel pans and sealed with O-rings. The samples will be initially cooled to -20°C (at 20°C/ min cooling rate) with 30 ml/ min nitrogen purge. The samples will then be heated to 200°C and then cooled to -20°C at the same condition. Thermal parameters such as glass transition temperature (Tg), enthalpy (ΔH), maximum denaturation temperature (Tm), and onset of the crystallization temperature (To), corresponding to the endothermic peak areas on the DSC thermogram will be determined by integrating the temperature vs. heat flow curve (Mathew et al. 2006). Analysis of the thermograms will be done using the Universal Software that is a part of the operation system.Thermogravimetric analysis (TGA) This will be done using a Hi-Res Modulated TGA 2950 Thermogravimetric Analyzer with Universal Analysis software package v.3.9a (TA Instrument Corp. New Castle, Delaware). For this test, film samples (11 ± 0.5 mg) will be placed in platinum pans that will be flushed with 90mm Hg of nitrogen, and they will be scanned from 25 to 600ºC at a 30ºC/ min heating rate. Weight loss of the tested samples between 70-100°C will be considered as the total moisture in the samples.X-ray Diffraction AnalysisThe X-ray diffraction analysis will be done using a Rigaku Miniflex 600 diffractometer with a vertical goniometer (Cu Kα radiation λ= 1.542Å). This will be done at 40kV and 20mA and the X-ray intensities will be recorded with a scintillation counter having a scattering angel (2θ) at a range of 3-50o and a scanning speed of 1o/min. From the data collected, according to Bragg's Law, the percent crystallinity of each film will be determined using a method reported by Hermans and Weidinger (1961). This will allow for an understanding of the impact of the antimicrobial additives on the crystallinity of the films. The crystallinity of the films has a significant impact on its toughness, gas transmission, clarity and flexible properties. A knowledge of this is important since it will influence the applications to which the films are compatibility.Mechanical Testing by Dynamic Mechanical Analysis (DMA)The mechanical properties of the films will be determined using a stress-controlled Dynamic-Mechanical Analyzer (DMA 2980, TA Instruments, Surrey, England) at a frequency of 1Hz from -80 to 100oC and a heating rate of 5oC min-1. The storage ('E) and loss modulus ("E) as well as tan δ of the film samples will be testes as a function of temperature. Data collected from these analyses will be used to determine how the glass transition temperature (Tg) and modulus of the samples will be influenced by the added antimicrobial compounds (Mathew et al., 2006).