Research Publications (Food Safety)

The real‐time recombinase polymerase amplification (RPA) could complete the reaction at 35°C in 20 min, which is much faster and cheaper than real‐time polymerase chain reaction. Salmonella enterica serovars, Salmonella enteritidis and Salmonella typhimurium, were detected simultaneously by multiplex real‐time RPA method for the first time. The LOD of S. enteritidis and S. typhimurium without enrichment procedure was 102 CFU/25 g. After enrichment, the LOD was 10 CFU/25 g.

The combination of nisin, EDTA, and sulfite at a low dose of 0.625% exhibited higher antimicrobial activity than did a high dose of sulfite (1.25%) for shrimp preservation. Based on aerobic bacteria counts, psychrotrophic bacteria, and TVB‐N, shrimp treatment with combination of nisin, EDTA, and low‐dose sulfite were still acceptable within 10 days of storage.

Gaseous chlorine dioxide (ClO2) is a promising sanitizer for frozen products because of its efficacy under nonthermal and waterless conditions. Our pilot‐scale treatment of blueberries demonstrated that a significant reduction of 1.5 log CFU/g can be achieved against coliforms after ClO2 exposure. Our findings demonstrate a cost‐effective procedure that could be adapted to commercial processing.

The study was to evaluate the food safety knowledge and hygiene practices among food handlers. A total of 42 food handlers in 13 basic schools under the School Feeding Scheme, Soweto, South Africa were recruited for the study using purposive and convenience sampling methods for the respondents and institutions, respectively. A piloted self‐administered questionnaire was used.

Salmonella typhimurium is able to form biofilms as a resistance mechanism against antimicrobials; therefore, it represents a problem for assuring food safety and highlights the importance of research on anti‐biofilm technologies. In this study, S. typhimurium biofilms were inactivated with the combination of clove essential oil (CEO) and ultraviolet light (UV‐C). The volatile composition of the CEO determined by gas chromatography showed eugenol as the major constituent (82%).

In this study, a novel dual priming oligonucleotide (DPO) system‐based polymerase chain reaction (PCR; DPO system‐based PCR) assay, which detected the fimY gene of Salmonella, was developed for the fast food testing. The DPO system‐based PCR assay allowed a wide range of annealing temperatures at 48–68°C to efficiently amplify fimY gene with an analytical detection limit of 1.2 × 102 CFU/ml for Salmonella in pure cultures and artificially contaminated food matrix.

The use of nutmeg essential oil‐loaded sage seed mucilage‐based coating with oxygen barrier effect along with antioxidant and antimicrobial activity enhanced the beef shelf‐life by lowering the moisture losses, microbial growth rate, and oxidation reaction progression, as well as by improving the sensory properties of the product.

The study conducted on 39‐layer farms in Gauteng Province, South Africa determined the prevalence and resistance of enteropathogens, and antimicrobial residues in table eggs collected from the farms. Eggs were tested for the presence of bacteria using standard methods. The resistance of bacteria to eight antimicrobial agents was determined using the disc diffusion method.

A model for growth of Salmonella Newport on Romaine lettuce as a function of time and temperature was developed and validated in Excel using Neural Tools and @Risk. The model simulates growth of a chicken isolate of Salmonella Newport on Romaine lettuce following cross‐contamination from raw chicken during meal preparation.

A key unmet food safety need remains the objective assessment of human milk spoilage. Experiments were conducted using a simplified human milk spoilage model based on goat's milk as a human milk surrogate, spiked with a single bacterial strain (S. epidermidis), in which pH and carbon dioxide (CO2) concentration were measured along with bacteria count over 160 hr. Bacteria count correlated highly with CO2 concentration but not with pH.

Key findings: The biodegradable coating of chitosan with extract and EO of lemon verbena had a significant effect on chemical changes and microbial population in rainbow trout meat and as they kept the sensory properties including color, taste, texture, odor, and overall acceptance scores. The CH‐LVE 1%‐LVEO 0.5% coating treatment prepared a kind of active coating that may be applied as an excellent preservative for fish meat in vacuum packaging.

Assays to evaluate killing of Listeria monocytogenes by the protozoan Tetrahymena pyriformis were developed. Listeria were killed at an exponential rate for the first 4 hr of coculture with Tetrahymena. Nineteen diverse strains of Listeria were equally susceptible to killing by Tetrahymena. Tetrahymena phagocytized and killed both planktonic and adherent Listeria.

Fish gelatin‐pectin (GelExt/Pec) composite films incorporated with Mentha pulegium essential oil (MEO) and Lavandula angustifolia essential oil (LEO) at two concentrations (0.5% and 1.5%) were developed and their physicochemical, mechanical, and antimicrobial properties were determined. GelExt/Pec‐based film incorporated with 1.5% MEO (GelExt/Pec + 1.5% MEO) showed the highest antimicrobial activity against all bacterial strains tested.

Study objective was to determine efficacy of a bacteriophage suspension against Listeria spp. when applied to three common types of materials used in food manufacturing facilities. Materials included two food contact materials (stainless steel and polyurethane thermoplastic belting) and one noncontact material (epoxy flooring). Coupons of each material were inoculated with a cocktail containing L. monocytogenes and L. innocua (4 to 5‐log10 CFU/cm2).

The study assessed the antibacterial and antifungal effect of Moringa oleifera seed marinade on smoked Clarias gariepinus stored at ambient temperature for 15 days. The optimum effective concentration of moringa seed marinade that acts as antibacterial was found best to be 11.2 g/kg of fish moringa marinade. While 12.08 g/kg exhibited the highest anti‐yeast effect in Clarias gariepinus and 10.6 g/kg serves as anti‐fungi.

Arabic gum has an interesting antioxidant and antimicrobial properties. Arabic gum can be used as a natural emulsifier and egg substitution in vegan mayonnaise. The manufacture of mayonnaise with Arabic gum was useful in controlling the development of rancidity. Abstract The main factors affecting the spoilage of mayonnaise are lipid oxidation and microbial contamination.

Many laboratories sampling foods for Salmonella are interested only in presence or absence of Salmonella, so only one colony may be selected. The objectives of this study were to use two selective enrichment broths and two selective agar plating media for Salmonella recovery from naturally contaminated broiler carcass rinsates and evaluate these media combinations on Salmonella serotypes recovered from each carcass.

A newly isolated Campylobacter jejuni bacteriophage CJ01 was partially characterized and might be a potential biocontrol agent to improve food safety. Abstract Campylobacter jejuni is a major foodborne pathogen causing acute bacterial enteritis worldwide. Screening of novel bacteriophages as biocontrol tools to eliminate C. jejuni in food during pre‐ and postharvest is an emerging research field. In this study, we partially characterized C.

Process lethality during a 5 min resting period for E. coli O157 C37 and J3, and E. coli AW1.7 in patties cooked to 71°C. F2, single‐sided cooking with flipping twice; F3, single‐sided cooking with flipping three times; D, double‐sided cooking. Abstract This study assessed the adequacy of the current cooking recommendations in relation to heat resistant Escherichia coli by evaluating eight potentially heat resistant E. coli strains (four generic and four E. coli O157:H7) along with AW1.7.

Pasteurized trim milk was irradiated through coiled tube ultraviolet (UV‐C) reactor. Pasteurization followed by UV‐C treatment can increase shelf life of milk. UV‐C can inactivate spores under ambient conditions. Abstract The demand for minimally processed foods has increased in the last few years and gains high acceptability among consumers as it has better nutritional value than highly processed foods.

The present study investigated in vitro antimicrobial activity of Eryngium caeruleum essential oil (EEO) against some of the fish spoilage and fish‐borne pathogenic bacteria. Moreover, its effects on specific spoilage microorganisms, inoculated Listeria monocytogenes, and its sensory changes in minced fish were evaluated. The results showed that EEO had a significant in vitro antimicrobial effect on the studied bacteria.

Alpha diversity boxplots showing the distribution of Chao1 diversity for produce items. The Chao1 alpha diversity is presented for samples from farm fresh (cucumbers, tomatoes, and kale) and organic (squash and green bell peppers) produce items collected 1, spiepr146 24, and 96 hr after treatment with water, chlorine, PAA, or SalmoFresh. Abstract Diets rich in minimally processed foods are associated with numerous health benefits, in part, due to their diverse, natural microbiota.

Salmonella were detected in 3 of 24 cucumbers, all of which were multidrug‐resistant and one was acid‐resistant. In addition, developed dynamic model showed that the Salmonella isolates proliferated gradually in cucumber under changing temperature, simulating storage condition. These results suggest that cross‐contaminated Salmonella could increase during storage. It may lead to human infection, and the treatment may be hard because of antibiotic resistance.

The apple‐, carrot‐, and hibiscus‐based edible films containing carvacrol and cinnamaldehyde showed antimicrobial effects against Escherichia coli O157:H7 on organic leafy greens in sealed plastic bags. All three types of 3% carvacrol‐containing films reduced E. coli O157:H7 population by about 5 log CFU/g at day 0. The 1.5% carvacrol‐containing films reduced E. coli O157:H7 population by 1–4 logs CFU/g at day 7.

The current study demonstrated that SEU promoted the proinflammatory activity of macrophage via upregulation of AIF‐1 expression. The expression of AIF‐1 was inferred by RNAi and the interference abolished the increase of cell proliferation and inflammatory cytokine TNFα, IL6 secretion.