This research was conducted to study the growth of Listeria monocytogenes inoculated on frankfurters stored at different conditions as a basis for a safety-based consume by shelf life date label. ...Three L. monocytogenes strains were separately inoculated at 10 to 20 CFU/cm2 onto frankfurters that were previously formulated with or without high pressure and with or without added 2% potassium lactate (PL) and 0.2% sodium diacetate (SD). Inoculated frankfurters were air or vacuum packaged; stored at 4, 8, or 12 C; and L. monocytogenes and psychrotrophic plate counts were determined for 90, 60, and 45 days, respectively, or until the stationary phase was reached. The data (log CFU per square centimeter versus time) were fitted using the Baranyi-Roberts model to determine maximum growth rates and lag-phase time. The maximum growth rates and the lag time under each growth condition were used to calculate the time to reach 100-fold the initial Listeria population. In frankfurters lacking PL and SD, the count of all strains increased by 2 log after 18 to 50 days at 4 C and 4 to 13 days at 8 C. The growth was inhibited at 4 and 8 C in frankfurters containing PL and SD, but one ribotype was capable of growing, with the time to reach 100-fold the initial Listeria population ranging from 19 to 35 days at 12 C. In most cases, the time to reach 100-fold the initial Listeria population of L. monocytogenes was significantly longer in vacuum-packaged frankfurters as compared with air-packaged samples. Inclusion of PL and SD also inhibited the growth of psychrotrophs, but at all temperatures the psychrotrophic plate counts were greater than 4 log CFU/cm2 at the end of the experiments. These results indicated that despite the use of antimicrobials, certain L. monocytogenes strains could be capable of growing under storage-abuse conditions. Growth kinetics data could be useful for establishing a shelf life date label protocol under different handling scenarios.
Heterocyclic aromatic amines (HAs) are a group of mutagenic and carcinogenic substances present in significant amounts in cooked meat and fish that can potentially be formed during food processing ...operations. This paper proposes a capillary liquid chromatography method with diode array detection for the trace-level determination of three HAs, namely, MeIQx (2-amino-3,8-dimethylimidazo4,5-fquinoxaline), norharman (9H-pyrido3,4-bindole) and harman (1-methyl-9H-pyrido3,4-bindole), in ready-to-eat (RTE) cooked ham processed by electron-beam (accelerated electrons) irradiation to eliminate pathogenic microorganisms and to extend its shelf-life. The HAs selected have frequently been detected and quantified in a wide range of food and could be potential markers to indicate the presence of these toxic compounds. The method is based on the separation in an Inertsil C₈ capillary column (150 mm x 0.3-mm internal diameter, 3 μm) by gradient elution mode using a mixture of acetonitrile and 30 mM ammonium acetate pH 4.5 buffer as the mobile phase. Detection was at 250 and 265 nm and, to improve sensitivity, large injection volumes (20 μL) and on-column focusing techniques based on the injection of HA samples in low organic solvent strength solutions were employed. A simple and short solid-phase extraction and purification procedure was also optimized for sample preparation. Nonirradiated and irradiated RTE cooked ham samples at doses between 1 and 8 kGy were analyzed. HAs were not detected in any of the samples analyzed; so both types of samples were spiked at concentration levels in the range 5-25 ng g⁻¹, which may be found in meat products. The quality parameters of the method developed in the food matrix were established, and detection limits around 0.3 ng g⁻¹ were obtained. Spiked recoveries between 70 and 79% (n = 3 for each spiked level) relative standard deviations between 1 and 5% were also obtained, showing the effectiveness of the proposed method.
The relationship between laboratory and field ratings was investigated for six different appetizers, including four ready-to-reconstitute mixes and two ready-to-eat munches. Liking ratings on a ...5-point hedonic scale were obtained from an Indian Army field study at base level as well as at an altitude of 11,500
ft above sea level and for the same appetizers in the laboratory. The field trials of the six products were conducted in two phases and results revealed that the products were more acceptable at altitude, with increased liking scores as compared to base level. Subjective ratings for hunger revealed that at altitude, appetizer consumption had stimulated the appetite of the soldiers. The ability of laboratory ratings to predict acceptability of foods consumed under realistic conditions appears to depend on the convenience of the appetizer as well as the environmental conditions and the psycho-physiological status of the participants. The appetizers received higher ratings at altitude because of the pungent and spicy nature of appetizer mixes as compared with base field and laboratory conditions. However, for all the appetizers the pungent and sweet taste of the appetizer munches was highly preferred.
gained popularity in recent times because they can be ingested without further thermic treatments. In this work, the microbiological quality and safety of 90 samples of RTE foods manufactured by ...small Costa Rican industries was determined to evaluate whether they represent a Public Health risk. Twenty-six samples of pickled vegetables, 18 dips, 18 salads, and 12 sweet treats were studied. Each sample was analyzed with regard to its pH, the presence of culturable microbiological quality indicators and recognized foodborne pathogens (Salmonella, Listeria monocytogenes, Clostridium perfringens, C. botulinum, and Bacillus cereus) Selected genes encoding toxins of C. botulinum and C. perfringens were screened by PCR. Thirty-seven percent of the samples had a level of acidity that could allow the growth and proliferation of bacterial pathogens (pH >4.5). The shelf-life indicators were acceptable but only if the RTE foods are kept at adequate conditions of temperature and humidity. Sixty-four percent of the RTE foods had total coliforms values that evidence inadequate hygiene practices during its elaboration (MPN/g >1000). This result was confirmed by the finding of fecal coliforms in 56 % of the samples, which, by the way, are inacceptable for human consumption. All cultures for pathogens were negative, except for 4 samples that contained B. cereus. Toxins of C. botulinum were not detected and one single sample was positive for the PCR for C. perfringens. The elevated degree of fecal contamination detected in the RTE could be prevented by means of good manufacturing practices, better hygiene measures and a deeper attention to critical control points. Los alimentos listos para su consumo (ALC) son alimentos procesados que pueden consumirse sin ningún tratamiento térmico adicional, lo que ha incrementado su popularidad. El objetivo de este estudio fue determinar la inocuidad y calidad microbiológica de 90 ALC producidos por pequeñas industrias costarricenses, con el fin de evaluar el riesgo para la salud pública. Se analizaron 26 encurtidos, 18 aderezos, 18 ensaladas, 12 dulces en conserva y 16 antipastos. A cada muestra se le determinó el pH y la presencia por cultivo de indicadores de calidad microbiológica y de patógenos (Salmonella, Listeria monocytogenes, Clostridium perfringens, C. botulinum y Bacillus cereus); además, se investigó por PCR la presencia de genes que codifican por las toxinas de C. botulinum y C. perfringens. Un 37% de las muestras tuvo un nivel de acidez que podría permitir la proliferación de patógenos (pH >4.5). En general, los indicadores de vida útil fueron aceptables, siempre y cuando los ALC se mantengan en condiciones de temperatura y humedad adecuadas. Un 64% de las muestras presentó valores de coliformes totales que sugieren mala higiene en su elaboración (NMP/g >1000), que se confirma con el hallazgo de coliformes fecales en el 56% y que las hace inaceptables para el consumo humano. Todos los cultivos para patógenos fueron negativos, excepto cuatro para B. cereus. No se detectaron toxinas de C. botulinum y solo una muestra fue positiva para el PCR de C. perfringens. Este estudio evidencia una importante contaminación fecal en ALC, una situación indeseable y totalmente prevenible si se practican técnicas adecuadas de manejo de alimentos, de higiene y se presta mayor atención a los puntos críticos de control.
Acacia senegal (in the form of Super Gum™) and Anogeissus latifolia (in the form of gum Gatifolia SD) were used in the manufacture of ready to eat extruded cereal snack products. Inclusions rates ...were 0, 5, 10 and 15% w/w replacement levels for wheat flour from a control recipe. The inclusion of Super Gum™ and Gatifolia increased product expansion and reduced product density compared to a cereal flour based control snack product. Inclusion of the gum materials also decreased the hardness of the snack products whilst increasing the crispiness of the product (number of fracture peaks recorded during axial compression of samples). Glucose area under the curve (AUC) measurements obtained using in vitro digestion procedures illustrated that the potential glucose release of snack products was reduced by more than 30% by the inclusion of Gatifolia and Super Gum™ at 15% w/w compared to the control sample. Such a reduction in potential glucose release was not dose responsive. These results illustrate a potential nutritional benefit of the utilisation of Gatifolia and Super Gum™ in the ready to eat snack food sector of the food industry.
Listeria monocytogenes strains, isolated from various sources (food, environment, and animals), were used to test different PCR-based methods to investigate their capability to define the strain ...origin. RAPD-PCR with three primers and the SAU-PCR method, in which the DNA was first digested with the
Sau3A restriction endonuclease and then amplified with a primer designed on the restriction site, were carried out, and the profiles obtained were used to perform cluster analysis. Based on the cluster analysis of
Listeria spp. strains, obtained from international collections, the coefficient of similarity was selected. The results obtained showed that the methods tested in the study gave different levels of differentiation between the strains tested. The RAPD protocol using the P1254 primer and the SAU-PCR gave appreciable results only for strains isolated from animals and from a food processing plant in two different periods of the year 2003. Better differentiation was observed using the RAPD-PCR with primer D8635. As a matter of fact, it was able to distinguish
L. monocytogenes obtained from different species of animals, different food samples and strains from the same production plant isolated in different periods of the year. Also primer M13 gave positive results, but the coefficient of similarity to use had to be increased to 80%. On the basis of the results observed, RAPD-PCR with primers D8635 and M13 should be considered reliable tools for epidemiological investigations focusing on
L. monocytogenes.
This study evaluated the antilisterial effects of salad dressings, as well as oils mixed with lemon juice or vinegar, on frankfurters during simulated home storage, without or with prior microwave ...oven heating. Frankfurters were inoculated (2.4
±
0.1 log CFU/cm
2) with
Listeria monocytogenes (10-strain mixture) and stored aerobically in bags at 7 °C. At 0, 7 and 14 days, frankfurters were immersed (5 or 20 min, 25
±
2 °C) in sunflower oil plus lemon juice or vinegar, extra virgin olive oil plus lemon juice or vinegar, or salad dressings (i.e., Vinaigrette, Ranch, Thousand island, and Caesar), or distilled water (DW), without or with prior microwave oven heating (1100 Watts, 2450 MHz, high power) for 30 s. Samples were analyzed for microbial growth during storage, and survivors following application of treatments, on tryptic soy agar plus 0.6% yeast extract and PALCAM agar. Immersion in salad dressings and in the combinations of oils with lemon juice or vinegar caused significant (
P
<
0.05) reductions of
L. monocytogenes, compared to dipping in DW. Reductions increased with previous product storage, from 0.5–0.9 (day-0) to 1.2–2.1 (day-14) log CFU/cm
2, as levels of contamination also increased. Reductions of pathogen counts by each treatment increased (
P
<
0.05) when applied following exposure to microwave oven heating; ranging from 1.2–1.9 (day-0) to 2.2–3.3 (day-14) log CFU/cm
2. Reductions were not (
P
≥
0.05) different between 5 and 20 min of immersion in most treatments. In general, the reduction effects of salad dressings decreased in the order of sunflower or extra virgin olive oil plus vinegar ≥ sunflower or extra virgin olive oil plus lemon juice > Caesar ≥ Thousand island ≥ Ranch ≥ Vinaigrette. The results of the present study indicated that salad dressings and oils with lemon juice or vinegar may contribute to control of
L. monocytogenes on ready-to-eat meat products in the home environment, especially when these products are treated and used in salads.
The objective of this study was to investigate the practicality of designing a heat treatment process in a food manufacturing operation for a product governed by a Food Safety Objective (FSO). ...Salmonella in cooked poultry meat was taken as the working example. Although there is no FSO for this product in current legislation, this may change in the (near) future. Four different process design calculations were explored by means of deterministic and probabilistic approaches to mathematical data handling and modeling. It was found that the probabilistic approach was a more objective, transparent, and quantifiable approach to establish the stringency of food safety management systems. It also allowed the introduction of specific prevalence rates. The key input analyzed in this study was the minimum time required for the heat treatment at a fixed temperature to produce a product that complied with the criterion for product safety, i.e., the FSO. By means of the four alternative process design calculations, the minimum time requirement at 70 degrees C was established and ranged from 0.26 to 0.43 min. This is comparable to the U.S. regulation recommendations and significantly less than that of 2 min at 70 degrees C used, for instance, in the United Kingdom regulation concerning vegetative microorganisms in ready-to-eat foods. However, the objective of this study was not to challenge existing regulations but to provide an illustration of how an FSO established by a competent authority can guide decisions on safe product and process designs in practical operation; it hopefully contributes to the collaborative work between regulators, academia, and industries that need to continue learning and gaining experience from each other in order to translate risk-based concepts such as the FSO into everyday operational practice.
The Thriposha programme is a community-level nutrition intervention in Sri Lanka that provides a combination of energy, protein and micronutrients as a ‘ready-to-eat’ cereal-based food. We measured ...the bioavailability of Fe and Zn from Thriposha formula at two different molar ratios of Zn:Fe in order to determine the effect on Fe and Zn absorption. Children 4–7 years (n 53) were given a meal prepared with 50 g Thriposha containing 1·5 mg Zn as zinc sulphate and either 9 mg (high Fe concentration (HiFe)) or 4·5 mg (low Fe concentration (LoFe)) Fe as ferrous fumarate. Zn and Fe percent absorption were measured using stable isotopes by tracer:tracee ratio and by incorporation of erythrocytes, respectively. Percent Fe absorption from the two meals was similar (6·6 % (4·8) v. 4·8 % (2·6); P = 0·15), but total Fe absorption was significantly higher from the HiFe meal (0·59 (0·43) mg) than the LoFe meal (0·20 (0·12) mg; P = 0·01). There was no significant difference between the two groups in Zn absorption (10·7 % (0·9) v. 8·8 % (1·4), P = 0·13, respectively). Decreasing the amount of Fe in Thriposha did not cause a significant change in the percent absorption of Fe and Zn, but significantly lowered the total amount of absorbed Fe. These results demonstrate the utility of maintaining a higher Fe content in this supplement. Further studies to increase Zn content are warranted while maintaining a HiFe.
Ready-to-eat poultry frankfurters were irradiated by electron-beam at medium doses of 0, 1, 2 and 3
kGy and evaluated for sensory characteristics over a 32 day refrigerated storage period. A ...descriptive panel identified and rated 31 attributes describing the effects of irradiation dose on the appearance, aroma, flavor and texture of the frankfurters throughout the shelf-life. It was found that storage time had a more significant effect on frankfurters than irradiation dose. Irradiation affected the aroma attributes of chicken, cured meat, spice blend, and wet dog; the flavor attributes of meaty, chickeny, and off-flavor; and the taste attributes of sour and sweet. The texture of the poultry frankfurters was not significantly affected by irradiation.
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