This study analyzed the effect of pH (X1), temperature (X2) and inulin amount (X3) on transformation of isoflavones (daidzin and daidzein) to equol in soymilk fermented with Bifidobacterium spp. All responses significantly (p 0.05) difference between the experimental and predicted values, suggested the suitability of established models in explaining the daidzin and daidzein transformation to equol as a function of pH, temperature and inulin.
Reduced graphene oxide (rGO) has emerged as a promising nanomaterial for reliable detection of pathogenic bacteria due to its exceptional properties such as ultrahigh electron transfer ability, large surface to volume ratio, biocompatibility, and its unique interactions with DNA bases of the aptamer. In this study, rGO-azophloxine (AP) nanocomposite aptasensor was developed for a sensitive, rapid, and robust detection of foodborne pathogens. Besides providing an excellent conductive and soluble rGO nanocomposite, the AP dye also acts as an electroactive indicator for redox reactions. The interaction of the label-free single-stranded deoxyribonucleic acid (ssDNA) aptamer with the test organism, Salmonella enterica serovar Typhimurium (S. Typhimurium), was monitored by differential pulse voltammetry analysis, and this aptasensor showed high sensitivity and selectivity for whole-cell bacteria detection. Under optimum conditions, this aptasensor exhibited a linear range of detection from 108 to 101 cfu mL-1 with good linearity (R 2 = 0.98) and a detection limit of 101 cfu mL-1. Furthermore, the developed aptasensor was evaluated with non-Salmonella bacteria and artificially spiked chicken food sample with S. Typhimurium. The results demonstrated that the rGO-AP aptasensor possesses high potential to be adapted for the effective and rapid detection of a specific foodborne pathogen by an electrochemical approach. Graphical abstract Fabrication of graphene-based nanocomposite aptasensor for detection of foodborne pathogen.
BACKGROUND: Despite the extensive research carried out to develop natural antifungal preservatives for food applications, there are very limited antifungal agents available to inhibit the growth of spoilage fungi in processed foods. Scope and Approach: Therefore, this review summarizes the discovery and development of antifungal peptides using lactic acid bacteria fermentation to prevent food spoilage by fungi. The focus of this review will be on the identification of antifungal peptides, potential sources, the possible modes of action and properties of peptides considered to inhibit the growth of spoilage fungi. Key Findings and Conclusions: Antifungal peptides generated by certain lactic acid bacteria strains have a high potential for applications in a broad range of foods. The mechanism of peptides antifungal activity is related to their properties such as low molecular weight, concentration and secondary structure. The antifungal peptides were proposed to be used as bio-preservatives to reduce and/or replace chemical preservatives.
The challenges to fulfill the demand for a safe food supply are dramatically increasing. Mycotoxins produced by certain fungi cause great economic loss and negative impact on the sustainability of food supplies. Moreover, the occurrence of mycotoxins at high levels in foods poses a high health threat for the consumers. Biological detoxification has exhibited a high potential to detoxify foodstuffs on a cost-effective and large scale. Lactic acid bacteria showed a good potential as an alternative strategy for the elimination of mycotoxins. The current review describes the health and economic impacts associated with mycotoxin contamination in foodstuffs. Moreover, this review highlights the biological detoxification of common food mycotoxins by lactic acid bacteria.
This study was conducted to characterize the growth of and aflatoxin production by Aspergillus flavus on paddy and to develop kinetic models describing the growth rate as a function of water activity (a(w)) and temperature.
The aim of this study was to model the radial growth rate and to assess aflatoxin production by Aspergillus flavus as a function of water activity (a(w) 0.82 to 0.92) and temperature (12 to 42 °C) on polished and brown rice. The growth of the fungi, expressed as colony diameter (mm) was measured daily, and the aflatoxins were analyzed using HPLC with a fluorescence detector. The growth rates were estimated using the primary model of Baranyi, which describes the change in colony radius as a function of time. Total of 2 secondary models were used to describe the combined effects of a(w) and temperature on the growth rates. The models were validated using independent experimental data. Linear Arrhenius-Davey model proved to be the best predictor of A. flavus growth rates on polished and brown rice followed by polynomial model. The estimated optimal growth temperature was around 30 °C. A. flavus growth and aflatoxins were not detected at 0.82 a(w) on polished rice while growth and aflatoxins were detected at this a(w) between 25 and 35 °C on brown rice. The highest amounts of toxins were formed at the highest a(w) values (0.90 to 0.92) at a temperature of 20 °C after 21 d of incubation on both types of rice. Nevertheless, the consistencies of toxin production within a wider range of a(w) values occurred between 25 to 30 °C. Brown rice seems to support A. flavus growth and aflatoxin production more than the polished rice.
Isolation of bacteriocinogenic lactic acid bacteria (LAB) from the Malaysian mould-fermented product tempeh and characterization of the produced bacteriocin(s).
The aim of the present study was to evaluate the physicochemical and antioxidant properties of Malaysian monofloral honey samples-acacia, pineapple and borneo honey-and compare them with tualang honey. Acacia and pineapple honey are produced by Apis mellifera bees while borneo and tualang honey are produced by Apis cerana and Apis dorsata bees, respectively.
Dieback disease caused by Erwinia mallotivora is a major threat to papaya plantation in Malaysia. The current study was conducted to evaluate the potential of endophytic lactic acid bacteria (LAB) isolated from papaya seeds for disease suppression of papaya dieback. Two hundred and thirty isolates were screened against E. mallotivora BT-MARDI, and the inhibitory activity of the isolates against the pathogen was ranging from 11.7-23.7 mm inhibition zones. The synergistic experiments revealed that combination of W. cibaria PPKSD19 and Lactococcus lactis subsp. lactis PPSSD39 increased antibacterial activity against the pathogen. The antibacterial activity was partially due to the production of bacteriocin-like inhibitory substances (BLIS). The nursery experiment confirmed that the application of bacterial consortium W. cibaria PPKSD19 and L. lactis subsp. lactis PPSSD39 significantly reduced disease severity to 19% and increased biocontrol efficacy to 69% of infected papaya plants after 18 days of treatment. This study showed that W. cibaria PPKSD19 and L. lactis subsp. lactis PPSSD39 are potential candidate as biocontrol agents against papaya dieback disease.
Improper handling, poor hygienic practices, and lack of environmental control affect the safety of street-vended beverages. The objective of this study is to determine the bacterial contamination level of three types of beverages (cordial-based drinks, milk-based drinks, fruit juices) sold by street vendors at Chow Kit, Kuala Lumpur. A total of 31 samples of beverages were analyzed to determine total viable count (TVC), total coliform, Escherichia coli, and Staphylococcus aureus counts via the standard plate count method. The results showed that only 9.7% of the total samples were not contaminated with the tested microorganisms. All milk-based drink samples were positive for TVC and also had the highest average bacterial counts at 5.30 ± 1.11 log Colony Forming Unit/mL (CFU/mL). About 71% of the samples were contaminated with total coliform with the average readings ranging between 4.30 and 4.75 log CFU/mL, whereas 58.1% of the samples were positive with S. aureus, with fruit juices having the highest average reading (3.42 ± 1.15 log CFU/mL). Only one sample (milk-based drink) was E. coli positive. This study showed that the microbiological safety level of street-vended beverages in Chow Kit, Kuala Lumpur was average and needs to be improved. Provision of food safety education and adequate sanitary facilities at vending sites are suggested to increase the safety of food products.
Two traditional fermented food 'tapai' (fermented tapioca) and 'tempoyak' (fermented durian flesh), chilli puree and fresh goat's milk were used as sources for the isolation of lactic acid bacteria (LAB). A total of 126 isolates were obtained and by sequential screening for catalase activity and Gram-staining, 55 were determined to be LAB out of which 16 were established to be homofermentative by the gel plug test. Seven isolates were identified by use of the API 50CHL kit and two lactobacilli strains and one lactococci strain were selected to study their growth and lactic acid production profiles in a time course experiment. The lactobacilli strains, both isolated from 'tapai', produced higher amounts of cells and lactic acid from glucose as compared to the lactococci strain isolated from fresh goat's milk.
Research was conducted to manufacture and evaluate a restructured turkey breast product using the Fibrimex cold-set binding system, sodium diacetate (NaD), and sodium lactate (NaL) and to ascertain effects of the treatments on proximate composition, pH, psychrotrophic organisms, water activity, onset of rancidity (TBA), thaw loss, cooking yields, and objective color, and sensory characteristics. Whole turkey breasts were cut into 5-cm-thick strips; treated with either water only (control), 1.5% NaL, 2.0% NaL, 0.1% NaD, 1.5% NaL + 0.1% NaD, or 2.0% NaL + 0.1% NaD; blended with Fibrimex ingredients; stuffed into casings; and stored at -30 degrees C for 0, 1, 2, and 3 mo. After each storage period, frozen chubs were tempered at 4 degrees C, sliced into 1-cm-thick steaks, packaged in retail trays, stored at 0 degrees C to simulate retail storage, and analyzed after 0, 2, 4, 6, 8, and 10 d. Sodium diacetate used alone or in combination with NaL reduced (P < 0.05) growth of psychrotrophic organisms and had no adverse effects on water activity, pH, cooking yield, fat, moisture, protein, objective color, onset of rancidity, and sensory characteristics (juiciness, turkey flavor intensity, and tenderness). Panelists reported slight off-flavor in all steaks treated with NaL. Treating steaks with NaL alone or in combination with NaD resulted in increased (P < 0.05) ash content. Sodium lactate also functioned to minimize thaw loss in the frozen restructured turkey product.
The growth and survival of Salmonella typhimurium in goat milk samples at different shifting temperatures were evaluated. The growth of S. typhimurium at lower temperatures (5°C, 10°C, and 15°C) exhibited bacteriostatic effects in milk, whereas at ambient temperature (25°C) and at 45°C, this pathogen luxuriantly grew throughout the 12-h stationary phase. At 50°C this pathogen was found to be thermotolerant and could still thrive in the milk. Overall, shifting temperatures from 37°C to 55°C and 60°C clearly indicated S. typhimurium to have reached complete elimination. The results demonstrated that the adaptation and survival of this pathogen directly depend on temperature stress. It is expected that the results will be useful to dairy industries for implementation of good manufacturing practices with a better hazard analysis critical control point approach to predict the microbial risk assessment and also benefit the consumers.
This study aimed to identify Listeria spp. and L. monocytogenes, characterize the isolates, and determine the antibiotic resistance profiles of the isolates Listeria spp. and L. monocytogenes in fresh produce, fertilizer, and environmental samples from vegetable farms (organic and conventional farms). A total of 386 samples (vegetables, soil, water, and fertilizer with manure) were examined. The identification of bacterial isolates was performed using PCR and characterized using ERIC-PCR and BOX-PCR. The discriminating power of the typing method was analyzed using Simpson's Index of Diversity. Thirty-four (n=34) Listeria isolates were subjected to antimicrobial susceptibility test using the disc-diffusion technique. The PCR analysis revealed that Listeria spp. were present in 7.51% (29/386) of all the samples (vegetable, soil, fertilizer, and water). None of the samples examined were positive for the presence of L. monocytogenes. Percentages of 100% (15/15) and 73.30% (11/15) of the Listeria spp. isolated from vegetables, fertilizer, and soil from organic farm B had indistinguishable DNA fingerprints by using ERIC-PCR and BOX-PCR, respectively. Listeria spp. isolated from 86 samples of vegetable, fertilizer, and environment of organic farm A and conventional farm C had distinct DNA fingerprints. Simpson's Index of Diversity, D, of ERIC-PCR and BOX-PCR is 0.604 and 0.888, respectively. Antibiotic susceptibility test revealed that most of the Listeria spp. in this study were found to be resistant to ampicillin, rifampin, penicillin G, tetracycline, clindamycin, cephalothin, and ceftriaxone. The isolates had MAR index ranging between 0.31 and 0.85. In conclusion, hygienic measures at farm level are crucial to the reduction of Listeria transmission along the food chain.
The objectives of this study were to determine the occurrence of Campylobacter spp. in live chickens sold at wet markets in Selangor, Malaysia and the multidrug resistance (MDR) profiles of the isolates. Cloacal swabs were taken from the chickens before slaughter and their caecal mucosae were swabbed after slaughter. Of the 90 chickens examined, 68 (75.6%) were positive for Campylobacter. Campylobacter were recovered from caecal swabs (53/90) and cloacal swabs (34/90) and Campylobacter coli (46 isolates) were identified slightly more than Campylobacter jejuni (41 isolates), but these differences were not significant (p<0.05). The most frequently observed resistance was to cephalothin (95.5%), followed by tetracycline (80.8%), erythromycin (51.4%), enrofloxacin (42.4%) and gentamicin (24.4%). Multidrug resistance (resistant to four or more antibiotics) was detected in 35.3% isolates. Campylobacter jejuni showed nine resistance profiles and the most common was to gentamicin-eryhtromycin-enrofloxacin-cephalothin-tetracycline (32.4%) combination while C. coli showed six profiles, with cephalothin-tetracycline (32.2%) combination being most common.
Kitchen mishandling practices contribute to a large number of foodborne illnesses. In this study, the transfer and cross-contamination potential of Vibrio parahaemolyticus from bloody clams to ready-to-eat food (lettuce) was assessed. Three scenarios were investigated: 1) direct cross-contamination, the transfer of V. parahaemolyticus from bloody clams to non-food contact surfaces (hands and kitchen utensils) to lettuce (via slicing), was evaluated; 2) perfunctory decontamination, the efficacy of two superficial cleaning treatments: a) rinsing in a pail of water, and b) wiping with a kitchen towel, were determined; and 3) secondary cross-contamination, the microbial transfer from cleaning residuals (wash water or stained kitchen towel) to lettuce was assessed. The mean of percent transfer rates through direct contact was 3.6%, and an average of 3.5% of total V. parahaemolyticus was recovered from sliced lettuce. The attempted treatments reduced the transferred population by 99.0% (rinsing) and 94.5% (wiping), and the relative amount of V. parahaemolyticus on sliced lettuce was reduced to 0.008%. V. parahaemolyticus exposure via secondary cross-contamination was marginal. The relative amount of V. parahaemolyticus recovered from washed lettuce was 0.07%, and the transfers from stained kitchen towel to lettuce were insubstantial. Our study highlights that V. parahaemolyticus was readily spread in the kitchen, potentially through sharing of non-food contact surfaces. Results from this study can be used to better understand and potentially raising the awareness of proper handling practices to avert the spread of foodborne pathogens.
Consumption of iced beverages is common in Malaysia although specific research focusing on its safety parameters such as presence of faecal coliforms and heavy metal elements remains scarce. A study conducted in Kelantan indicated that faecal coliforms were detected in the majority of the ice cube samples analyzed, largely attributable to improper handling. Hence, it was found pertinent to conduct similar study in other parts of the country such as Johor Bahru if the similar pattern prevailed. Therefore, this present cross sectional study which randomly sampled ice cubes from 30 permanent food outlets in Taman Universiti, Johor Bahru for detecting contamination by faecal coliforms and selected heavy metal elements (lead, copper, manganese and zinc) acquires significance. Faecal coliforms were detected in 11 (36.67%) of the samples, ranging between 1 CFU/100 mL to > 50 CFU/100 mL; two of the samples were grossly contaminated (>50 CFU/100 mL). Interestingly, while positive detection of lead was observed in 29 of the 30 ice cube samples (mean: 0.511±0.105 ppm; range: 0.489-0.674 ppm), copper, manganese and zinc were not detected. In addition, analysis on commercially bottled mineral water as well as in tap water samples did not detect such contaminations. Therefore, it appears that (1) contamination of faecal coliforms in ice cubes in food outlets in Malaysia may not be sporadic in pattern but rather prevalent and (2) the source of water used for manufacturing the ice cubes that contained significant amount of lead would suggest that (3) it was neither originated from the treated tap water supply nor bottled mineral water or (4) perhaps contaminated during manufacturing process. Further studies exploring the source of water used for manufacturing these ice cubes as well as the handling process among food operators deserve consideration.
A disposable horseradish peroxidase (HRP)-based electrochemical genosensor was developed for chronoamperometric detection of single-stranded asymmetric lolB gene PCR amplicon (118 bp in length) of the food-borne pathogen, Vibrio cholerae. A two-step sandwich-type hybridization strategy using two specific probes was employed for specific detection of the target single-stranded DNA (ssDNA). The analytical performances of the detection platform have been evaluated using a synthetic ssDNA (ST3) which was identical to the target single-stranded amplicon and a total of 19 bacterial strains. Under optimal condition, ST3 was calibrated with a dynamic range of 0.4883-15.6250 nM. By coupling asymmetric PCR amplification, the probe-based electrochemical genosensor was highly specific to the target organism (100% specificity) and able to detect as little as 0.85 ng/μl of V. cholerae genomic DNA.
Since the introduction of the molecularly imprinting technology (MIT) in 1970s, it becomes an emerging technology with the potential for wide-ranging applications in food manufacturing, processing, analysis and quality control. It has been successfully applied in food microbiology, removal of undesirable components
from food matrices, detection of hazardous residues or pollutants and sensors. Molecularly imprinted solid-phase extraction (MISPE) is the most common application so far. The review describes the methods of making the molecularly imprinted polymer systems, the application of the technology in food safety issues and the remaining challenges.
Lactobacillus plantarum is a non-gas-producing lactic acid bacterium that is generally regarded as safe (GRAS) with Qualified Presumption of Safety (QPS) status. Although traditionally used for dairy, meat and vegetable fermentation, L. plantarum is gaining increasing significance as a probiotic. With the newly acclaimed gut-heart-brain axis, strains of L. plantarum have proven to be a valuable species for the development of probiotics, with various beneficial effects on gut health, metabolic disorders and brain health. In this review, the classification and taxonomy, and the relation of these with safety aspects are introduced. Characteristics of L. plantarum to fulfill the criteria as a probiotic are discussed. Emphasis are also given to the beneficial functions of L. plantarum in gut disorders such as inflammatory bowel diseases, metabolic syndromes, dyslipidemia, hypercholesteromia, obesity, and diabetes, and brain health aspects involving psychological disorders.