Category Archives: Food Technology

Research – Ultrashort-pulse lasers kill bacterial superbugs, spores

Science Daily

Life-threatening bacteria are becoming ever more resistant to antibiotics, making the search for alternatives to antibiotics an increasingly urgent challenge. For certain applications, one alternative may be a special type of laser.

Researchers at Washington University School of Medicine in St. Louis have found that lasers that emit ultrashort pulses of light can kill multidrug-resistant bacteria and hardy bacterial spores. The findings, available online in the Journal of Biophotonics, open up the possibility of using such lasers to destroy bacteria that are hard to kill by other means. The researchers previously have shown that such lasers don’t damage human cells, making it possible to envision using the lasers to sterilize wounds or disinfect blood products.

“The ultrashort-pulse laser technology uniquely inactivates pathogens while preserving human proteins and cells,” said first author Shaw-Wei (David) Tsen, MD, PhD, an instructor of radiology at Washington University’s Mallinckrodt Institute of Radiology (MIR). “Imagine if, prior to closing a surgical wound, we could scan a laser beam across the site and further reduce the chances of infection. I can see this technology being used soon to disinfect biological products in vitro, and even to treat bloodstream infections in the future by putting patients on dialysis and passing the blood through a laser treatment device.”

Tsen and senior author Samuel Achilefu, PhD, the Michel M. Ter-Pogossian Professor of Radiology and director of MIR’s Biophotonics Research Center, have been exploring the germicidal properties of ultrashort-pulse lasers for years. They have shown that such lasers can inactivate viruses and ordinary bacteria without harming human cells. In the new study, conducted in collaboration with Shelley Haydel, PhD, a professor of microbiology at Arizona State University, they extended their exploration to antibiotic-resistant bacteria and bacterial spores.

The researchers trained their lasers on multidrug-resistant Staphylococcus aureus (MRSA), which causes infections of the skin, lungs and other organs, and extended spectrum beta-lactamase-producing Escherichia coli (E. coli), which cause urinary tract infections, diarrhea and wound infections. Apart from their shared ability to make people miserable, MRSA and E. coli are very different types of bacteria, representing two distant branches of the bacterial kingdom. The researchers also looked at spores of the bacterium Bacillus cereus, which causes food poisoning and food spoilage. Bacillus spores can withstand boiling and cooking.

In all cases, the lasers killed more than 99.9% of the target organisms, reducing their numbers by more than 1,000 times.

Viruses and bacteria contain densely packed protein structures that can be excited by an ultrashort-pulse laser. The laser kills by causing these protein structures to vibrate until some of their molecular bonds break. The broken ends quickly reattach to whatever they can find, which in many cases is not what they had been attached to before. The result is a mess of incorrect linkages inside and between proteins, and that mess causes normal protein function in microorganisms to grind to a halt.

“We previously published a paper in which we showed that the laser power matters,” Tsen said. “At a certain laser power, we’re inactivating viruses. As you increase the power, you start inactivating bacteria. But it takes even higher power than that, and we’re talking orders of magnitude, to start killing human cells. So there is a therapeutic window where we can tune the laser parameters such that we can kill pathogens without affecting the human cells.”

Heat, radiation and chemicals such as bleach are effective at sterilizing objects, but most are too damaging to be used on people or biological products. By inactivating all kinds of bacteria and viruses without damaging cells, ultrashort-pulse lasers could provide a new approach to making blood products and other biological products safer.

“Anything derived from human or animal sources could be contaminated with pathogens,” Tsen said. “We screen all blood products before transfusing them to patients. The problem is that we have to know what we’re screening for. If a new blood-borne virus emerges, like HIV did in the ’70s and ’80s, it could get into the blood supply before we know it. Ultrashort-pulse lasers could be a way to make sure that our blood supply is clear of pathogens both known and unknown.”

Story Source:

Materials provided by Washington University School of Medicine. Original written by Tamara Bhandari. Note: Content may be edited for style and length.

Research – Peanut Skins as a Natural Antimicrobial Feed Additive to Reduce the Transmission of Salmonella in Poultry Meat Produced for Human Consumption

Journal of Food Protection

Salmonella is the leading cause of bacterial foodborne zoonoses in humans. Thus, the development of strategies to control bacterial pathogens in poultry is essential. Peanut skins, a considerable waste by-product of the peanut industry is discarded and of little economic value. However, peanut skins contain polyphenolic compounds identified that have antimicrobial properties. Hence, we aim to investigate the use of peanut skins as an antibacterial feed additive in the diets of broilers to prevent the proliferation of Salmonella Enteritidis (SE). One hundred sixty male hatchlings (Ross 308) were randomly assigned to, (1) PS: peanut skin diet without SE inoculation (2) PSSE: peanut skin diet and SE inoculation 3) CON: control diet without SE inoculation (4) CONSE: control diet with SE inoculation. Feed intake and body weights were determined at week 0 and 5. On days 10 and 24 post hatch, 3 birds/pen (24 total) from each treatment group were euthanized and the liver, spleen, small intestine, and ceca were collected. The weights of the liver, spleen and ceca were recorded. Organ invasion was determined by counting SE colonies. Each pen served as an experimental unit and was analyzed using a t-test. Performance data was analyzed in a completely randomized design using a general linear mixed model to evaluate differences. There were no significant differences ( P > 0.05) in weekly average pen body weight, total feed consumption, bird weight gain and feed conversion ratio between the treatment groups. There were no significant differences in SE CFU/g for fecal, litter or feed between treatment groups CONSE and PSSE. However, for both fecal and litter, the PSSE treatment group tended (P ≤0.1) to have a lower Salmonella CFU/g compared to the CONSE treatment group. The results indicate that peanut skins may have potential application as an antimicrobial feed additive to reduce the transmission or proliferation of SE in poultry environments or flocks.

Research – Gaseous chlorine dioxide inactivation of microbial contamination on whole black peppercorns

Wiley Online

Black peppercorn is a common ingredient imported and used in uncooked or ready-to-eat foods in the United States. They might be exposed to fecal coliforms and other microbial contamination due to a lack of good agricultural and manufacturing practices in some developing countries under which they were grown and harvested, thus causing economic losses to the peppercorn industry in the United States. We investigated the effect of gaseous chlorine dioxide (ClO2) on reducing the microbial population levels of coliforms, aerobic bacteria, yeasts, and molds on unprocessed black peppercorns. Treatments on peppercorns were conducted in a 30-L airtight chamber, and equal amounts of dry media precursors were used to generate gaseous ClO2. Whole peppercorns (200 g) were exposed to 20, 30, and 40 g of precursor dose for up to 60 min at 21 ± 0.4°C and in combination with mild heat at 40 ± 2°C. Aerobic bacteria, coliforms, yeasts, and molds on peppercorns were enumerated before (7.4, 7.2, and 7.1 log CFU/g, respectively) and after treatments. Results after treatment demonstrated 0.8–1 log10 (90%) reduction for all the microbes post-treatment at 21 ± 0.4°C. The treatments conducted with a 30 g precursor dose for 60 min at 21 ± 0.4°C reduced statistically higher (p < .05) microorganisms than those at 40 ± 2°C. Our work demonstrated that gaseous ClO2 could be used as a part of an overall hurdle technology to reduce the coliforms, aerobes, yeasts, and molds on black peppercorns without affecting the visual quality.

Research – Israeli antimicrobial coating eliminates listeria 100% in factory pilot


Israeli company Bio-Fence has created an antimicrobial coating that eliminated all traces of a deadly foodborne illness in a recent test.

An Israeli antimicrobial coating has managed to eliminate all traces of a deadly foodborne illness in a recent test conducted in a hot dog peeling room at a major sausage manufacturing facility in Israel.
The company, Bio-Fence, developed the coating, which was applied to the floor and lower part of the walls of the room which, despite repeated and strict disinfectant routines, had experienced high levels of listeria, particularly on the production floor.
Listeria is one of the deadliest foodborne illnesses. According to the US Food and Drug Administration, even if treated aggressively with antibiotics, as many as 30% of infected people die and more than 90% of people are hospitalized – often in intensive care units.
In the three weeks before the proof-of-concept (POC) pilot in which Bio-Fence’s coating was applied, listeria was detected in 21 out of 23 (91%) daily floor samples. After application, the bacteria were completely undetectable on the floor surface during day-to-day production.

Research – The Bactericidal Efficacy and the Mechanism of Action of Slightly Acidic Electrolyzed Water on Listeria monocytogenes’ Survival


In the present work, the bactericidal efficacy and mechanism of slightly acidic electrolyzed water (SAEW) on L. monocytogenes were evaluated. The results showed that the strains of L. monocytogenes were killed completely within 30 s by SAEW whose available chlorine concentration (ACC) was higher than 12 mg/L, and it was confirmed that ACC is the main factor affecting the disinfection efficacy of SAEW. Moreover, our results demonstrated that SAEW could destroy the cell membrane of L. monocytogenes, which was observed by SEM and FT-IR, thus resulting in the leakage of intracellular substances including electrolyte, protein and nucleic acid, and DNA damage. On the other hand, the results found that SAEW could disrupt the intracellular ROS balance of L. monocytogenes by inhibiting the antioxidant enzyme activity, thus promoting the death of L. monocytogenes. In conclusion, the bactericidal mechanism of SAEW on L. monocytogenes was explained from two aspects including the damage of the cell membrane and the breaking of ROS balance. View Full-Text

Research – The combined effect of green tea and peppermint oil against pathogenic bacteria to extend the shelf life of eggs at ambient temperature and the mode of action

Wiley Online

This work investigated the antimicrobial activities of green tea (GT) at 5 and 10.0% wt/vol and peppermint oil (PP) at 0.1, 0.15, and 0.2% wt/vol against major pathogen bacteria (Escherichia coliSalmonella enteritidis, and Staphylococcus aureus) found on eggs at room temperature (30°C). The quality factors (weight loss, Haugh unit, albumen pH, egg yolk, and albumen index) of treated eggs were also measured while they were stored at room temperature for 14 days. A 9-point hedonic scale was used for sensory evaluation. Scanning electron microscopy was used to examine the morphology of bacteria cells to understand this study’s mechanism of action. It was found that combining 10% GT and 0.15% PP had complete antibacterial activity against all pathogenic bacteria investigated, and could extend the shelf life of treated eggs from 7 days (control) to at least 14 days. The treated egg’s coliforms (≤3.0 log10 colony-forming unit [CFU] g−1), Ecoli (≤1.8 log10 CFU g−1), TVC (≤4.3 log10 CFU g−1), Salmonella spp., (not detected in 25 g), and Saureus (not detected in 25 g) were better able to meet the microbiological criteria for egg after 14 days of storage, when compared to the control, which exceeded the criteria within 7 days. In addition, consumers rated egg acceptability as favorable by giving a sensory score ranging from like slightly to like moderately (~6.7). Furthermore, when compared to the control (6–7 days), all treated eggs retained their quality during storage for 14 days and met the microbiological criteria for egg in food standard (<4.7–6.0 log10 CFU g−1 for total visible count). Compound leakage from within the bacteria, which was the mode of action when GT and PP were combined, resulted in a wrinkled appearance of bacteria cells and serious defects in bacteria membrane morphology. These findings suggest that a sanitizing spray derived from GT and PP can extend the shelf life of eggs and ensure their safety for human consumption at room temperature without using a refrigerator.

Research – New Trends in Photodynamic Inactivation (PDI) Combating Biofilms in the Food Industry—A Review


Biofilms cause problems in the food industry due to their persistence and incompetent hygiene processing technologies. Interest in photodynamic inactivation (PDI) for combating biofilms has increased in recent years. This technique can induce microbial cell death, reduce cell attachment, ruin biofilm biomolecules and eradicate structured biofilms without inducing microbial resistance. This review addresses microbial challenges posed by biofilms in food environments and highlights the advantages of PDI in preventing and eradicating microbial biofilm communities. Current findings of the antibiofilm efficiencies of this technique are summarized. Additionally, emphasis is given to its potential mechanisms and factors capable of influencing biofilm communities, as well as promising hurdle strategies.

Australia – Barossa Fine Foods ham products – Listeria monocytogenes


Barossa Fine Foods ham products 

Date published: 25 October 2021

Product information

Knoll Consultants and Investments Pty Ltd is conducting a recall of two ham products. Please see below for further information.​​

Food safety hazard

Food products contaminated with (listeria monocytogenes) may cause illness if consumed. Listeria may cause illness in pregnant women and their unborn babies, the elderly and people with low immune systems.

Country of origin


What to do​

Consumers should not eat this product. Any consumers concerned about their health should seek medical advice and should return the products to the place of purchase for a full refund.

For further information please contact:

Knoll Consultants and Investments (trading under Barossa Fine Foods)

08 8255 3900

Research – Survival of Salmonella enterica in Military Low Moisture Food Products during Long Term Storage at 4°C, 25°C and 40°C

Journal of Food Protection

Salmonella enterica  has been increasingly implicated in foodborne outbreaks involving low moisture foods (LMF) during the recent decade. This study aimed to investigate the potential for persistence of  Salmonella enterica  in a range of low moisture foods (LMF) during storage at 3 temperatures. LMF products, boil-in-bag eggs (freeze dried product), chocolate protein drink, cran-raspberry first strike bars, mocha dessert bar, and peanut butter, were inoculated with a five strain cocktail of S. enterica and stored at 4°C, 25°C, or 40°C for 36 mos. Salmonella populations remained above 7 log CFU/g in all products stored at 4°C and above 6 log CFU/g in products stored at 25°C excluding the cran-raspberry bars. Storage at 40°C resulted in Salmonella populations above 5.5 log CFU/g in boil-in-bag eggs after 36 mos and demonstrated survivability for 12 mos or less in the other five products.  Additionally, a mocha bar production temperature profile study identified rapid cooling of bars in which the temperatures reached would have no measurable impact on  Salmonella  populations. The results indicate the ability of  Salmonella  to survive in a variety of LMF category foods even under adverse storage conditions and identifies how the food matrix may affect  Salmonella  survivability. The data indicate the importance of establishing food processing procedures that adequately mitigate the presence of Salmonella throughout food processing systems while also increasing comprehensive understanding of Salmonella survivability mechanisms.

Research – Nisin-based antimircobial combination with cold plasma treatment inactivate Listeria monocytogenes on Granny Smith apples

Science Direct


A nisin-based antimicrobial and cold plasma combination treatments in reducing Listeria monocytogenes inoculated on apple surfaces purchased from a New Jersey farm and a supermarket in Philadelphia area was investigated. All apples were spot inoculated or by submersion in 107 CFU/ml L. monocytogenes inoculum. Populations of L. monocytogenes recovered on farm and supermarket apples after spot inoculation averaged 5.8 ± 0.24 log CFU/g and 4.6 ± 0.12 log CFU/g, respectively and 4.1 ± 0.22 log CFU/g and 3.6 ± 0.12 log CFU/g, respectively on submerged apples. All apples were treated with antimicrobial solution for 30 s, 40 s, 3 min (180s) and 1 h (3600 s), cold plasma treatments for 30 and 40s, and a combination of antimicrobial and cold plasma treatments and the surface structure of apples were examined using scanning electron microscopy (SEM). Cold plasma treatment at 40s, followed immediately with antimicrobial treatments at 180s and 3600 s led to 2.5 and 4.6 log CFU/g inactivation of L. monocytogenes, respectively. SEM observation showed changes on apple surface structures but not on bacterial cell structure. This result suggests that this combination treatments is effective in killing L. monocytogenes on apple surfaces.