A good temperature management, such as precooling and cold storage, can delay deterioration of fresh produce. In this study, different forced-air precooling times were applied on Musa AAA Berangan to investigate the influence of forced-air precooling time on the changes of quality attributes and consumer acceptance. The banana was subjected to forced-air precooling treatment (5 ± 1°C) for 0, 14, 50, and 120 min and then stored in a cold room (13 ± 1°C) for 2 weeks. Then, all the fruits were transferred to a ripening room (25 ± 2°C) and initiated to ripen with ethylene gas. Quality attributes analyses and sensory evaluations were conducted when the fruits reached maturity index 5. Quality parameters, such as soluble solids concentration, titratable acidity, pulp firmness, and peel colour, showed no significant differences when fruits were precooled at different times. Blackening of peel as a result of chilling injury occurred in fruits treated with forced-air precooling for 50 and 120 min. This blackening significantly influenced consumer acceptance, although it did not affect the pulp colour and taste.
Listeriosis and salmonellosis are the major foodborne illnesses worldwide. Over the last decade,
increasing reports about the antibiotic resistance of Listeria monocytogenes and Salmonella from diverse sources have prompted public health concerns, especially in developing countries with over reliance or misuse of antibiotic drugs in the treatment of humans and animals. In this study, antibiotic susceptibility profiles of 58 L. monocytogenes and 12 Salmonella Enteritidis strains from vegetable farms and retail markets in Malaysia were testedby the standard disk diffusion method. Listeria monocytogenes isolates were found to exhibit 100% resistance to penicillin G. Also, high resistance patterns were observed for meropenem (70.7%) and rifampicin (41.4%). The multiple antibiotic resistance (MAR) index of L. monocytogenes isolates ranged from 0.11 to 0.56. Besides, the antibiogram results revealed that multidrugresistant (MDR) S. Enteritidis were detected and all the S. Enteritidis isolates demonstrated resistance to at least four antibiotics. Ampicillin, amoxicillin, and trimethoprim failed to inhibit all the S. Enteritidis strains. Salmonella Enteritidis isolates also displayed high resistance to nalidixic acid (75.0%), trimethoprim-sulfamethoxazole (75.0%), and chloramphenicol (66.7%). Findings in this study indicated that vegetables could be potential sources of multidrug resistance of L. monocytogenes and S. Enteritidis, which can be a serious issue and a major concern for public health. Thus, there is a great need for surveillance programs in Malaysia to continuously monitor the antibiotic resistance profiles of important pathogens.
Phytochemicals belonging to the group’s phenols, terpenes, betalains, organosulfides, indoles and protein inhibitors are important components in fruits, vegetables, legumes, whole grains and nuts that have health promoting benefits and a variety of applications in food and pharmaceutical industries. Initially only a few of these important phytochemicals are produced commercially by chemical synthesis. However, recent developments in the field of biotechnology have provided metabolic engineering strategies that use microorganisms as cell factories for high production of these products. This review will discuss the general biosynthetic pathways, metabolic engineering and optimization strategies of functional phytochemicals that have received a lot of attention from investigators.
The aim of this study was to assess the most probable number-polymerase chain reaction (MPNPCR) technique for detection of Listeria monocytogenes in salad vegetables in comparison with reference EN ISO 11290-2 and Food Drug Administration Bacteriological Analytical Manual method using artificial and naturally contaminated samples. Based on recovery of L. monocytogenes from artificially contaminated samples, MPN-PCR showed a moderate correlation (R=0.67) between spiking concentration and microbial levels which was better than the FDA-BAM method (R=0.642) and ISO 11290-2:1998 method (R=0.655). With naturally contaminated samples, it was found that L. monocytogenes was detected in 25% of the vegetable samples using MPN-PCR; 15% of the samples by the FDA-BAM method and 8% of samples using ISO 11290-2:1998 method. Overall, MPN-PCR was found to be a rapid and reliable method that could facilitate the enumeration of L. monocytogenes in vegetables.
Listeria monocytogenes is a gram positive, facultative intracellular pathogen with the capacity to cause
food poisoning outbreaks as well as severe illness in vulnerable human population groups. It can cause a rare but serious disease called listeriosis with high fatality rates (20–30%) compared with other foodborne microbial pathogens. Although Listeria monocytogenes is infective to all human population groups, it is more likely to cause severe problems among pregnant women, immunocompromised individuals, the elderly and neonates. There are a variety of phenotyphic and genotyphic methods for the detection of Listeria monocytogenes in foods. Recent technological advances have increased the ability of scientists to detect Listeria monocytogenes. The purpose of this review is to discuss molecular characteristics of the Listeria monocytogenes pathogen, standard detection methods of this pathogen in foods based on culture methods, confirmation of species and subtyping based on phenotypic and genotyphic methods.
The main source of E. coli 0157:H7 is cattle, but recent studies showed high percentage of outbreaks
contributed by contaminated water. The occurrence of E. coli O157:H7 in environmental water samples poses a potential threat to human health. The aim of this study was to establish a protocol for the detection of the pathogen E. coli O157:H7 and E. coli virulence genes (eaeA, rfbE, hly, stx1, and stx2) in a multiplex PCR protocol using six specific primer pairs. The target genes produced species-specific amplicons at 625 bp, 397 bp, 296 bp, 166 bp, 210 bp and 484 bp for E. coli O157:H7 (fliCh7 gene) and virulence genes (eaeA, rfbE, hly, stx1, and stx2) respectively. The results obtained show that the established PCR protocol is suitable for a rapid and specific analysis of the pathogenic E. coli O157:H7 in environmental water samples for the assessment of microbiological risks.
Successful DNA amplification is vital for the detection of specific DNA targets in feeds, and this in return depends on the ability of DNA extraction methods to produce good quality DNA. In this study, seven methods were compared for DNA extraction from feeds using quantitative polymerase chain reaction (PCR) of single copy maize (Zea mays) endogenous hmg (high mobility group) gene. Relative levels of hmg were used to evaluate the DNA quality. Spectrophotometer determination of DNA was also carried out to assess DNA yield and DNA purity, while electrophoretic analysis of genomic DNA extracts was carried out to investigate DNA integrity. The findings illustrate that the DNA extraction methods have a significant effect on DNA quality. Statistically, the Epicentre method extracted the highest DNA yield while the Wizard method had the lowest DNA yield with high DNA purity and integrity. However, the Wizard method recovered the most amplifiable DNA per reaction, indicating that template quality and integrity had greater influence over hmg amplification than DNA yield.
The introduction of new agricultural commodities and products derived from modernbiotechnology may have an impact on human and animal health, the environment and economiesof countries. As more Genetically Modified Organisms (GMO) enter markets worldwide, themonitoring of GMOs is being preferred for obvious reasons such as determination of seed purity,verification of non-GMO status of agricultural crops and fulfilling GMO labeling provisions, tomention a few. Numerous GMO analytical methods which include screening, identification andquantification have been developed to reliably determine the presence and/or amount of GMOin agricultural commodities, in raw agricultural materials and in processed and refined ingredients.The detection of GMOs relies on the detection of transgenic DNA or protein material. For routineanalysis, a good sample preparation technique should reproducibly generate DNA/protein ofsufficient quality, purity and yield while minimizing the effects of inhibition andcontamination.
The key sample preparation steps include homogenization, pretreatment, extraction andpurification. Due to the fact that analytical laboratories receive samples that are often processedand refined, the quality and quantity of transgenic target analyte (e.g. protein and DNA) frequentlychallenge the sensitivity of any detection method. With the development of GMO analysistechniques, the Polymerase Chain Reaction (PCR) technique has been the mainstay for GMOdetection, and the real-time PCR is the most effective and important method for GMOquantification. The choice of target sequence; for example a promoter, a terminator, a gene, or ajunction between two of these elements, is the single most important factor controlling the specificity of the PCR method. Recent developments include event-specific methods, particularlyuseful for identification and quantification of GM content. Although PCR technology has obvious
limitations, the potentially high degree of sensitivity and specificity explains why PCR in its various
formats, is currently the leading analytical technology employed in GMO analysis. Comparatively, immunoassays are becoming attractive tools for rapid field monitoring for the integrity of agricultural commodities in identity preservation systems, whereby non-specialised personnel can employ them in cost-effective manner. This review discusses various popular extraction methodologies and summarises the current status of the most widely used and easily applicable GMO analysis technologies in laboratories, namely the PCR and immunoassay technologies.
The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).
A total of 78 samples comprising different types of street foods, sold in different locations in Malaysia, were examined for the presence of Enterobacter cloacae. E. cloacae contamination was recorded in 9% of the samples examined. Tests for susceptibility to 12 different antibiotics showed that all were resistant to six or more antibiotics, but susceptible to chloramphenicol and gentamicin. Plasmids of four different sizes were detected from the three plasmid positive isolates. RAPD analysis using four primers yielded completely different banding patterns for all E. cloacae studied. In Malaysia, no published information on street foods in the epidemiological investigation of E.cloacae related disease is available. However, their occurrences have provided compelling evidence that the risk of disease transmission caused by E. cloacae through street foods is moderate.
This study aimed to determine the prevalence Listeria monocytogenes in raw chicken meat samples at hypermarkets and wet markets. Chicken drumsticks, breasts, and thighs were randomly selected. The most probable number (MPN) PCR method was used to quantify the L. monocytogenes in the samples. Listeria monocytogenes was detected in 20% of the samples. Occurrence of L. monocytogenes was highest in breast (42.03%) followed by drumstick (11.27%) and thigh (7.14%). Samples from hypermarkets showed higher occurrence (25.71%) of L. monocytogenes compared with wet markets (14.29%). The density of L. monocytogenes found in samples ranged from <3.0 to 16 MPN•g(-1). The presence of L. monocytogenes in raw chicken meat is unwanted but unpreventable. Thus, further research on the processing method to reduce and eliminate this kind of bacteria in chicken meat before consumption is necessary. The presence of L. monocytogenes in chicken samples suggests the importance of this pathogen in chicken. Thus, more study is needed to find ways to eliminate this pathogen from poultry.
Listeria monocytogenes (L. monocytogenes) is a serious food-borne pathogen for immunocompromised individuals. L. monocytogenes is capable of producing biofilm on the surface of food processing lines and instruments. The biofilm transfers contamination to food products and impose risk to public health. Transfers contamination to food products, and impose risk hazard to public health. The aim of this study was to investigate biofilm producing ability of L. monocytogenes isolates. Microtitre assay was used to measure the amount of biofilm production by ten L. monocytogenes isolates from minced chicken / meat, sausages and burgers. Results showed that all 10 L. monocytogenes isolates were able to form biofilm after 24 h at 20˚C on polystyrene surface (the common surface in food industries). Some strains were capable of forming biofilm more than the others. All strains showed a slight raise in the quantities of attached cells over 48 and 72 h. L. monocytogenes strains isolated from minced chicken, minced meat and burgers were better biofilm-producers comparing to the strains isolated from sausages.
Pathogenic Vibrio parahaemolyticus is one of the leading causes of bacterial gastroenteritis in many countries. Among the strains examined, 36 RAPD-types were found when amplified with primers OPA8 and OPA10. The analysis shows the majority of V. parahaemolyticus isolates originated from seafood were branched into four major clusters at 18.2%, 20.7% 34% and 3.4% similarity levels. This suggests that there is potential for a single strain to be distributed widely within a population and there also potential for multiple contaminating strains of different clonal lineages to be present within the same population. Optimum temperature (37ºC) was the highest and stable formation of biofilm. The total percentage of biofilm formation at 37ºC was 33.33% for each of weak, moderate and strong biofilm producers. Room temperature produces 61.1% of weak biofilm producer, while 13. 89% for moderate biofilm producers and produce 25% of strong biofilm. While a total of 91.67% weak biofilm producers at 4ºC and 8:33% for room temperature and no growth of strong biofilm. Upon analysis, strong biofilm was tracked from the largest group at 37°C and room temperature which produce 27.27% of strong biofilm producer respectively. Interestingly, they are derived from cockles.
Irrespective of its health effects, street foods are very popular with the consumers. The main
purpose of this research was to study the biosafety of Escherichia coli in popiah, a Malaysian
street food sold at a roadside food stall and a restaurant in Sri Serdang, Selangor, Malaysia,
using the combination of the most probable number (MPN)-Polymerase Chain Reaction
(PCR) assay-plating on Eosin Methylene Blue (EMB) agar methods. Using these biomolecular
methods, E. coli was detected in 12/15 (80%) and 11/15 (73%) of the collected samples from
the roadside food stall and the restaurant respectively. The incidence of stx virulence-associated
genes was detected in 1/15 (7%) among the E. coli isolated from samples taken from the
roadside food stall while the E. coli isolated from the restaurant was 3/15 (20%). The density
of E. coli ranged from 1100 MPN/g and the density of E. coli positive with stx genes
was
Salmonella has caused foodborne illnesses globally and it has been a rising threat on fresh produce. The objective of this study was to determine the prevalence and concentration of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in freshly prepared fruit juice sold at hawker stalls. Analysis was conducted by employing most probable number-polymerase chain reaction (MPN-PCR). A total of 50 freshly prepared fruit juices were examined and the prevalence of Salmonella spp., Salmonella Typhi and Salmonella Typhimurium in the fruit juices were 34%, 20% and 10%, respectively, with an estimated microbial load varying from 0 to 42 MPN/g. Of the five different fruits, carrot juice had the highest prevalence of Salmonella spp. (60%) and Salmonella Typhi (40%). However, Salmonella Typhimurium was detected in apple (30%), orange (10%) and starfruit juice (10%). Factors contributing to the presence of Salmonella were cross-contamination and poor sanitation practice. Besides, negligence on temperature and storage time also led to the growth of Salmonella. Proper monitoring and risk assessment are needed in order to establish control measures to ensure the quality and safety of fruit juices in Malaysia.
Escherichia coli and Escherichia coli O157 were identified from “selom” (Oenanthe stolonifera), “pegaga” (Centella asiatica), beef, chicken, lamb, buffalo, “ulam Raja” (Cosmos caudatus) and “tenggek burung” (Euodia redlevi). The bacteria were recovered using chromagenic agar. Isolated Escherichia coli and Escherichia coli 0157 were further characterized by plasmid profiling and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). The virulence genes of the isolates (VT1, VT2, LT, ST, eaeA, inV) that produces pathogenic Escherichia coli and 16S rRNA gene were screened by a multiplex PCR assay. The plasmid profiling analysis showed that out of 176 isolates, only 103 isolates contained plasmids. ERIC-PCR analysis generated amplified products in the range of ~150 bp to > 1000 bp categorizing isolates into a total of 52 different profiles. Multiplex PCR showed that 20 (32.3%) of the isolates carried eaeA gene, 6 (9.7%) isolates possessed inV genes, only 1 (1.6%) have VT2 genes and 1 (1.6%) as well carried VT1 genes, 2 (3.2%) of the isolates harboured LT genes, and only 1 (1.6%) isolate possessed ST genes. There were no correlation between plasmid, ERIC-PCR and virulence genes profiles.
The organic foods’ market is becoming one of the rapidly growing sections in agricultural economies in the world. During the last two decades, food-borne outbreaks associated with fresh produce have rapidly increased. E. coli O57:H7, the caustic agent of acute hemorrhagic diarrhea and abdominal cramps, is mainly associated with meat and poultry product outbreaks but frequent outbreaks linked to the consumption of vegetables have been reported. The aim of this study was to investigate prevalence of E. coli O157:H7 in some organic foods. A total of 230 organic food samples including four-winged bean, tomato, white radish, red cabbage, chinese cabbage, lettuce, cucumber and chicken form retailed groceries and supermarkets in Malaysia were investigated. Low prevalence of E. coli O157:H7 was detected in organic vegetables and chickens. The estimated quantity of E. coli O157:H7 in all samples ranged from 2400 MPN/g. The overall MPN/g estimate of E. coli O157:H7 in the samples from organic groceries was higher than supermarket with the maximum of >2400 MPN/g. Most of the samples from supermarket showed a minimum of
Legislation concerning the safety assessment and labelling of foodstuffs has been implemented in many countries. Consequential to a number of cases of food adulteration reported globally, a fast and reliable detection method for the food traceability is required in ensuring effective implementation of food legislation in a country. In this study, PCR-RFLP technique based on cyt b gene has been tested for its suitability for these purposes. This method combines the use of a pair of universal primer that amplifies a 359 bp fragment on the cyt b gene from meat muscle DNA and restriction enzyme analysis. Analysis of experimental beef frankfurter, minced beef, pork frankfurter and pork cocktail samples demonstrated the suitability of the assay for the detection of the beef (Bos taurus) and pork (Sus scrofa), but not applicable for some processed food, particularly detection of mackerel (Rasterelliger brachysoma), sardine (Saedinella Fimbriata) and tuna (Thunnus tonggol) origin in canned food. Commercial frauds through species mislabelling or misdescribed were not detected. The assay is demonstrated applicable for routine analysis of meat traceability of foodstuffs and legislation purposes, if sufficient availability of detectable mtDNA in the foodstuffs is ensured.
Caenorhabditis elegans (C. elegans) have been widely used as an infection model for mammalian related pathogens with promising results. The bacterial factors required for virulence in non-mammalian host C. elegans play a role in mammalian systems. Previous reported that Salmonella found in vegetable and poultry meat could be potential health hazards to human. This study evaluated the pathogenicity of various serovars of Salmonella enterica (S. enterica) that recovered from local indigenous vegetables and poultry meat using C. elegans as a simple host model. Almost all S. enterica isolates were capable of colonizing the intestine of C. elegans, causing a significant reduction in the survival of nematodes. The colonization of Salmonella in C. elegans revealed that the ability of S. enterica in killing C. elegans correlates with its accumulation in the intestine to achieve full pathogenicity. Using this model, the virulence mechanisms of opportunistic pathogenic S. enterica were found to be not only relevant for the interactions of the bacteria with C. elegans but also with mammalian hosts including humans. Hence, C. elegans model could provide valuable insight into preliminary factors from the host that contributes to the environmental bacterial pathogenesis scenario.
Local wood charcoal was used as the main component of the electrodes of an air-cathode microbial
fuel cell (air-cathode MFC) in current study. The air cathode was build with finely milled charcoal powder and cement plaster as binder; while anode was made up of a packed bed of charcoal granules. Mangrove estuary brackish water was inoculated in the anodic chamber as the fuel and a source of exoelectrogens. The constructed fuel cell was monitored by measuring the potential over time. The MFC generated a stable power density at 33mW/m2 (0.5V) under a load of 200Ω after 72 hours of operation. An open circuit voltage (OCV) of 0.7mV was obtained after 15 hours operating under open circuit. The result of power generation by the constructed fuel cell indicating that wood charcoal could be used as electrode in an MFC and that brackish water contained potential exoelectrogens. However, further investigation and modification is required to increase the performance of the fuel cell.