Synthesis of polyalkylacrylate nanolatexes by microemulsion polymerization method

The paper concerns with the radical polymerization of [octadecyl acrylate (ODA), isooctyl acrylate (iso-OA) and α-olefins 1-Octene (n-O)]. These microemulsions were stabilized by sodium dodecyl sulfate (SDS) and initiated by water-soluble initiator potassium persulfate (KPS). The nanolatex particle sizes were determined by transmission electron microscope (TEM). They were situated between 10 and 100 nm. The microstructures were confirmed by FT-IR and molecular weights determined by Gel permeation chromatography (GPC). The obtained M. wt. were (≈70 × 10³, 101 × 10³ and 153 × 10³ g/mol). The polydispersity, molecular weights, and particle sizes were discussed in the light of micelle formation and shape of the alkyl group via emulsion polymerization.     

Effect of washing and disinfecting containers on the microbiological quality of fresh milk sold in Bamako (Mali)

The present study aimed to improve the microbiological quality of the milk, from the cow’s udder to the selling point by container washing and disinfecting. The total counts (TC), Enterobacteriaceae counts (EBC) were used as quality indicators.The results showed a significant decrease of milk flora at the selling point, from 1.6 × 10⁷ ± 1.3 × 10⁷ (control) to 4.8 × 10⁵ ± 0,8 × 10⁷ (intervention) colony forming units per ml (cfu ml⁻¹) for TC and 1.2 × 10⁶ ± 1.1 × 10⁶ (control) to 0.9 × 10⁴ ± 1.1 × 10⁴ (intervention) cfu ml⁻¹ for EBC. The study suggests that in milk production area, besides udder infection and water quality, hygiene behaviour with respect to hand washing, container’s cleaning and disinfection are the key areas that remain of relevance to milk hygiene intervention.     

Microflora of traditional starter made from cassava for “attiéké” production in Dabou (Côte d’Ivoire)

Attiéké is a food made from cassava in Côte d’Ivoire by fermentation. The process uses a traditional starter. Studies on 81 starter samples from 3 villages showed that the dominant microflora consists of lactic acid bacteria (5.7 × 10⁷ cfu/g), yeasts (5.5 × 10⁷ cfu/g), Bacillus (3.8 × 10⁷ cfu/g), Enterococcus (3.0 × 10⁶ cfu/g), total coliforms (3.0 × 10⁶ cfu/g), thermotolerant coliforms (8.0 × 10³ cfu/g) and mould (2.0 × 10⁶ cfu/g). Lactic acid bacteria, Bacillus spp, yeasts, faecal Enterococci and moulds are organisms which could play a role in the cassava fermentation. Coliforms may indicate contamination from the environment during production.     

The occurrence of indicator bacteria on hands and aprons of food handlers in the delicatessen sections of a retail group

Despite an increase in the number of food handlers receiving food hygiene training, a high number of food poisoning outbreaks still occur as a result of improper food handling practices in the retail industry. In this study, samples were collected from the hands and aprons of food handlers in the delicatessen sections of a prominent South African retail group and analysed for the presence of total viable counts (TVC), total coliforms, Escherichia coli, members of the family Enterobacteriaceae and Staphylococcus aureus in order to assess the levels of contamination and to establish possible relationships. Noteworthy TVC were present on 98% of hands and 84% of aprons sampled and conformed to the national standard of 1 × 10² cfu cm⁻² without exception. Coliforms were present on 40% of food handler’s hands and on 26% of aprons and when compared to the literature which suggests a target value of <2.5 cfu cm⁻², 32% of food handlers exceeded the target with regard to hands and 8% with regard to aprons. E. coli was found to only exceed the limit in the case of one food handler. Enterobacteriaceae were present on the hands of food handlers (44%) and on aprons (16%), ranging between 5 and 1.8 × 10¹ cfu cm⁻² on hands and between 5 and 2.9 × 10¹ cfu cm⁻² on aprons. S. aureus counts were present on 88% of hands and 48% of aprons and ranged between negligible and 9.8 × 10¹ cfu cm⁻² for hands and up to 6.2 × 10¹ cfu cm⁻² for aprons. No significant statistical correlation occurred between the organisms on hands and aprons, indicating that the latter were not likely to be cross-contaminated by hands.     

Synthesis of phthalimide and succinimide copolymers and their evaluation as flow improvers for an Egyptian waxy crude oil

This paper describes the synthesis, characterization and performance evaluation of three phthalimide and three succinimide copolymers of vinyl acetate, styrene and methyl methacrylate as flow improvers for waxy crude oil. The prepared copolymers were named as; (VA)Ph; (St)Ph; (MMA)Ph; (VA)S; (St)S and (MMA)S. These copolymers were characterized by FTIR and ¹H NMR spectroscopy. The molecular weights and nitrogen content of these copolymers were determined by using the GPC technique and the Kjeldhal method, respectively. The rheological properties of crude oil (with and without additives) were studied. From the obtained results, it was remarked that the styrene phthalimide copolymer (St)Ph exhibited the maximum pour point depression (ΔPP_500 ppm = 30). The results of the rheological flow properties showed that the Bingham yield values (τ_β) for crude oil without additives at 15, 27 and 39 °C were 0.286, 0.131 and 0.075 Pa respectively, whereas the τ_β for the treated crude oil by the styrene phthalimide (St)Ph copolymer were 0.021, 0.0164 and 0.0081 Pa at 500 ppm at the same temperatures.     

Biological control of postharvest diseases of peach with Cryptococcus laurentii

Cryptococcus laurentii was evaluated for its activity in reducing postharvest gray mold decay, blue mold decay and Rhizopus decay of peach caused by Botrytis cinerea, Penicillium expansum and Rhizopus stolonifer respectively, and in reducing natural decay development of peach fruits. The concentrations of antagonist had significant effects on biocontrol effectiveness: the higher the concentrations of the antagonist, the lower the disease incidence. At concentrations of C. laurentii at 1 × 10⁹ CFU ml⁻¹, the gray mold decay was completely inhibited after 4 days incubation at 25 °C, while the control fruit had 50% decay, when inoculated with B. cinerea spores suspension of 1 × 10⁵ spores ml⁻¹; no complete control of the blue mold or Rhizopus mold was observed, when peach fruits were stored at 25 °C for 4 days (challenged with P. expansum) or 5 days (challenged with R. stolonifer) respectively, but the decay was distinctly prevented, the incidence of blue mold or Rhizopus mold was reduced by 78.6% or 80% respectively, compared with control, at challenged with P. expansum or R. stolonifer spores suspension of 5 × 10⁴ spores ml⁻¹, respectively. C. laurentii significantly reduced the natural development of decay and did not impair quality parameters of fruit following storage at 2 °C for 30 days followed by 20 °C for 7 days.     

Bacterial pathogens in fresh,smoked and salted Iranian fish

Salted and smoked fish are traditional products in Iran that are prepared by heavy salting (mixed salting) and heavy salting followed by cold smoking methods, respectively. Twenty eight Alosa kessleri (Caspian anadromous shad) from the Caspian Sea and 39 cultivated Hypophthalmichthys molitrix (silver carp) from two fish farms before and after a smoking process were examined using standard bacterial testing. Forty Liza aurata (Mullet dore) and 20 smoked H. molitrix purchased from a fish market (SMH-m) were also tested. Listeria monocytogenes were greater than 1 × 10² g⁻¹ in 2.6% of fresh (not smoked) H. molitrix (FH), 5.1% smoked H. molitrix, 20% SMH-m and 10% salted L. aurata (SAL). Vibrio parahaemolyticus was found in 21.4% fresh A. kessleri, 7.1% smoked A. kessleri, 5% SMH-m, 35% fresh L. aurata (FL) and 50% of SAL. For 7.5% of FL and 2.5% of SAL, V. parahaemolyticus were greater than 1 × 10² g⁻¹. Escherichia coli and Salmonella dublin were obtained in 30.8% and 2.6% of FH, respectively. No coliforms and Salmonella spp. were detected in salted fish and smoked fish. Staphylococcus aureus greater than 1 × 10⁵ cfu g⁻¹ were obtained in 55% SMH-m and 10% SAL. Consumption of these fish, either raw or undercooked may contribute to foodborne illness in Iran.     

A Turkey survey of hygiene indicator bacteria and Yersinia enterocolitica in raw milk and cheese samples

In this research, a total of 200 dairy (raw milk, cheese) samples obtained from Ankara, were examined for the presence of Yersinia spp., total coliform and Escherichia coli. As expected, raw milk 55% (55/100) were significantly contaminated with Yersinia spp., than cheese samples 14% (14/100). Y. enterocolitica was the most commonly isolated species, and was recovered from 47.3% in raw milk 35.7% in cheese samples. The other Yersinia spp. were identified as Y. frederiksenii (31.0%, 21.4%), Y. kristensenii (12.7%), Y. intermedia (7.2%, 7.1%) and atypical Yersinia spp. (1.8%, 35.7%) in raw milk and cheese samples, respectively. All the samples of cheese examined were negative for Y. kristensenii. All Y. enterocolitica strains tested gave negative results in the autoagglutination tests and crystal violet binding test.Furthermore total coliform bacteria and E. coli were investigated in these samples. According to the analysis results, most of the samples containing Yersinia spp.were found high number of viable count cell total coliform than E. coli. Total coliform bacteria and E. coli, were detected (3.0 × 10⁴ cfu/ml and 1.5 × 10⁴ cfu/ml) in four milk samples containing Y. enterocolitica while, they were detected (2.5 × 10⁴ cfu/ml and 1.0 × 10⁴ cfu/ml) in eight milk samples containing Y. enterocolitica. In the present study, total coliform bacteria and E. coli were detected >1.1 × 10⁵ cfu/g in six cheese samples containing Y. enterocolitica and atypical Yersinia spp. The results indicate that Yersinia spp. is more likely to be isolated from foods with a high level of coliforms than from foods with low coliform counts.     

Bacteriological quality of ice cream in Tripoli—Libya

ObjectiveTo determine the bacteriological quality of ice cream sold in Tripoli city and susceptibility of the isolated bacterial agents to the commonly used antibiotics.Materials and methodsOne hundred and sixty ice cream samples were collected from six different small and two large manufactures in Tripoli. Standard bacteriological techniques were used to determine the total bacterial count (TBC) and coliforms, isolate the pathogenic organisms and determine their susceptibilities to antibiotics.ResultsTBC of samples examined ranged between 3 × 10¹ and 5 × 10⁸ cfu/ml (mean = 6.9 × 10⁷) and the MPN values of coliforms between 0.0 and 11/ml (mean = 8). Of the samples studied Escherichia coli was isolated from 10 [including 2 serogroup O157] (6%), Salmonella spp. from 8 (5%), Aeromonas spp. from 30 (19%), Staphylococcus aureus from 60 (38%) and Listeria monocytogenes from 7 (4%). Nearly 80% of the samples examined did not conform to the Libyan Standards for Ice Cream (LSIC). Resistance to one antibiotic was detected in more than 80% of the isolated bacterial pathogens and multiple-drug resistance (resistance to three antibiotics) in 25%.ConclusionAntibiotic-resistant pathogenic bacteria is not uncommon in ice cream sold in Tripoli particularly from small manufactures. Application of the HACCP system should be introduced into the ice cream industry to improve the quality of such products manufactured in Libya.     

Determination of 3-chloro-1,2-propanediol in soy sauces by capillary electrophoresis with electrochemical detection

A capillary electrophoresis technique with electrochemical detection (CE-ED) for determination of 3-chloro-1,2-propanediol (3-MCPD) in soy sauces was described. Effects of several factors, such as the pH value and the concentration of the running buffer, separation voltage, injection time and the potential applied to the working electrode, were investigated to find the optimum conditions. With a 50 cm length of 25 μm diameter fused-silica capillary, well-defined separation of 3-chloro-1,2-propanediol from propanediol and glycerol was achieved in 30 mmol/L borate (pH 9.24) within 13 min. Operated in a wall-jet configuration, a 0.45 mm copper-disk electrode used as the working electrode exhibits good response at 0.65 V (vs. SCE) for the analyte in 0.05 mol/L sodium hydroxide solution. The linear range for 3-MCPD was from 2 × 10⁻⁴ g/mL to 6.6 × 10⁻⁶ g/mL. Notably, the detection limit (S/N = 3) of 1.3 × 10⁻⁷ g/mL for 3-chloro-1,2-propanediol coincides with the criterion of food safety. This method was successfully used in the rapid analysis of 3-MCPD in soy samples. The average recoveries of 93.8–106.8% indicated that the experimental results were satisfactory.     

The growth,physiology and toxigenic potential of Bacillus cereus in cooked rice during storage temperature abuse

The effect of storage temperature abuse on the growth and physiology of Bacillus cereus in cooked rice was examined using plate counting and flow cytometry (FCM). Concurrently, toxigenic potential was measured through recording phosphatidylcholine-specific phospholipase C (PC-PLC) activity. Rice spiked with endospores was incubated at 4 °C, 10 °C or 18 °C for 6 days. Growth was not recorded at 4 °C, whereas >1.0 × 10⁶ CFU g^?1 were detected at 10 °C and 18 °C. PC-PLC activity was temperature dependent and was not destroyed by microwaving. FCM population profiling complemented plate count data, providing novel physiological data e.g. on the membrane integrity, redox or intracellular activities of cells over time during low temperature incubation.     

Safe and shelf-stable natural casing using hurdle technology

Safe and shelf-stable natural casing were prepared using a combination of hurdles viz. reduced water activity, packaging and gamma irradiation. Washed lamb intestines were treated with common salt to reduce water activity to 0.80 ± 0.02, packed in polyethylene bags and subjected to gamma-irradiation (5 and 10 kGy). Control non-irradiated samples had high total viable counts (10⁶ CFU/g), aerobic spores (10³ CFU/g), spores of sulphite reducing clostridia (10³ CFU/g), potentially pathogenic bacteria such as staphylococci (10⁴ CFU/g) and coliforms (10² CFU/g). Treatment with gamma radiation resulted in a dose dependent reduction in counts of these microbes. A dose of 5 kGy was sufficient to reduce total viable counts by three log cycles; spore counts by two log cycles and completely eliminate staphylococci and coliforms. Samples subjected to a 10 kGy dose were devoid of any viable microbes. The reduced water activity of the product prevented growth of the microbes in natural casings during storage at room temperature. Sausages prepared using hurdle processed natural casing were examined for sensory and textural properties. It was observed that product acceptability and mechanical strength was not affected by radiation processing. Our studies indicated that shelf-stable and safe natural casing could be prepared using a combination of hurdles.     

Incidence of pathogenic psychrotrophs in ice creams sold in some retail outlets in Mumbai,India

With a view to determine the microbial quality of ice creams, 30 samples of commercial brands of three flavours sold in the `open' and `packaged, (cone, cup)' forms were analyzed for their total bacterial counts (TBC), yeast and mold counts (YMC), coliforms and pathogenic psychrotrophs; Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Yersinia enterocolitica and Salmonella spp. In general in both the types of ice creams bacterial load (2.3 × 10⁴–8.5 × 10⁶ cfu/ml) was higher; particularly coliform levels were 10–100 fold higher (3.0 × 10²–5.8 × 10⁴ cfu/ml) than the safety limits prescribed by Indian Standards Institute (ISI). Staph. aureus was detected in both the types of ice creams but occurrence of B. cereus was more frequent in open samples (40%) than in packed ones (26.6%). Salmonella was not detected in any of the 30 samples tested. While 53% of the packed and 100% of the open ice creams exhibited Listeria contamination, Yersinia were detected in 33% of packed and 40% of open ones. L. monocytogenes and/or Y. enterocolitica was detected only in one of the open ice cream samples. Growth profile of Y. enterocolitica 5692 and L. monocytogenes 036 at simulated temperature abuse conditions during commercial frozen storage showed that after 10 days L. monocytogenes could grow to >1 log and 1 log cycle at 8–10°C and 2–4°C, respectively and Y. enterocolitica grew 2 log cycles at both the temperatures. Results are discussed in the context of present microbiological specifications and the need for its implementation by regulatory agencies to ward off possible health hazards arising from pathogens.     

Exposure to ethyl carbamate in alcohol-drinking and nondrinking adults and its reduction by simple charcoal filtration

The risk of exposure to ethyl carbamate from the consumption of kimchi, soy sauce, and alcoholic beverages was assessed in alcohol-drinking and nondrinking adults. An alcohol-drinking adult obtains 5.6–9.2 ng/kg bw/day of ethyl carbamate through the addition of kimchi and soy sauce, while a nondrinking adult receives 3.3–4.0 ng/kg bw/day via kimchi and soy sauce alone. The average excess cancer risk of an alcohol-drinking adult (3.9 × 10^?7) was also twice higher than that of an adult who does not drink (1.9 × 10^?7). We achieved a maximum of 47% and 45% removal of the ethyl carbamate present in diluted spirits and soy sauce, respectively, through a simple charcoal filtration process. This resulted in a reduction of the average daily intakes of ethyl carbamate through diluted spirits and soy sauce from 1.7 and 2.2 ng/kg bw/day to 0.9 and 1.2 ng/kg bw/day, respectively.     

Degradation of aflatoxins in aqueous buffer in the presence of nucleophiles

This study compared the efficacies of lysine, glycine and methylamine to mediate aflatoxin destruction in heated aqueous phosphate buffers. A 3 × 3 × 4 factorial design (buffer pH, heating temperature and nucleophile) was followed. The buffer was artificially contaminated (“spiked”) with mixed aflatoxin standard and heated for specified time periods. After the heat treatment residual aflatoxins were determined using HPLC procedures.Aflatoxin reduction was influenced by the buffer pH and the pK_a of the added nucleophile. When phosphate buffer (at pH 9) was heated to 150 °C the degradation rate constants (k) aflatoxin in the presence of lysine, glycine and methylamine were 0.11, 0.09 and 0.08 min⁻¹ respectively. Addition of calcium chloride to the “spiked” buffer lowered aflatoxin reduction, but upon adding lysine or methylamine, aflatoxin reduction was restored to some extent. These findings demonstrate the potential capability of lysine to mediate aflatoxin reduction.     

Control of Fusarium moulds and fumonisin B1 in seeds by gamma-irradiation

The distribution of naturally occurring Fusarium moulds producing fumonisin B₁ in seeds was determined. Fusarium infection of seed samples ranged from 10% to 60%, Fusarium moniliforme was the predominant species. Fusarium counts in wheat seeds were 8.1 × 10⁴ CFU/g, 6.3 × 10⁶ CFU/g in maize and 4.8 × 10³ CFU/g in barley. Wheat, maize and barley seeds naturally contaminated with varying levels of fumonisin B₁ 1.4–5.8, 8.0–13.8 and 0.1–0.5 μg/g, respectively. F. moniliforme and Fusarium proliferatum were major Fusarium contaminants producing fumonisin B₁. The effect of gamma irradiation on Fusarium moulds and levels of fumonisin B₁ was also determined. The viable counts of Fusarium in seeds decreased by increasing the radiation dose levels and the growth of Fusarium spp. was inhibited at 4.0 kGy for barley and 6.0 kGy for wheat and maize. Application of radiation dose at 5 kGy inactivated fumonisin B₁ by 96.6%, 87.1% and 100% for wheat, maize and barley, respectively, and a dose of 7 kGy was sufficient for complete destruction of fumonisin B₁ in wheat and maize.     

Occurrence of Listeria spp. in Brazilian fresh sausage and control of Listeria monocytogenes using bacteriophage P100

Since the 1980s, an increase in outbreaks of human listeriosis linked to contaminated food has been a concern of health authorities. Intensively manipulated foods, such as Brazilian fresh sausage, are frequently responsible for food-borne diseases. In this work the occurrence of Listeria monocytogenes and the efficacy of bacteriophage P100 (LISTEX?) to control the microorganism was evaluated in Brazilian fresh sausage. Eighty samples were analyzed, 40 each of swine and chicken Brazilian fresh sausage. Listeria spp. were isolated from 12 samples (15%), of which three (3.75%) were positive for L. monocytogenes. L. monocytogenes strains isolated belonged to serotype 1/2a. L. monocytogenes 1/2a was inoculated in Brazilian fresh sausage (2.1 × 10⁴ cfu/g) with the bacteriophage added thereafter (3.0 × 10⁷ pfu/g). Samples were analysed immediately (day zero) and then stored at 4 °C for 10 days. The bacteriophage P100 reduced L. monocytogenes counts by 2.5 log units at both 0 and 10 days compared to controls without bacteriophage. In spite of this, the populations of L. moncytogenes increased over the 10 day storage. Our data demonstrate that in one of the samples the use of the bacteriophage dropped the bacteria count below the level of direct detection. This study demonstrates a new alternative for pathogen control in the food industry, especially in the processes used to produce Brazilian fresh sausage.     

Meat species identification based on the loop mediated isothermal amplification and electrochemical DNA sensor

An easy, rapid and sensitive method of detection of the presence of meat species in raw or processed foods is important from cultural, religious, health and commercial perspectives. In this study we have tried to distinguish species-specificity in control and processed pork, chicken and bovine meats using loop mediated isothermal amplicons (LAMP) and disposable electrochemical printed (DEP) chips. LAMP is a nucleic acid amplification method that amplifies target DNA with high specificity, efficiency and rapidity under isothermal condition (63 °C). Electrochemical genosensor with the DEP chips detects the amplicons by Linear Sweep Voltammetry (LSV) observation of DNA–Hoechst33258 interaction on the chip surface. Hoechst33258 interacts with DNA in solution without immobilization of DNA onto the electrode surface eliminating the time consuming probe immobilization step. Our method is more specific and free of unwanted amplifications compared to Multiplexed PCR (M-PCR) method and gave limits of detection of ∼20.33 ng/μl (3 × 10⁴ copies/reaction), ∼78.68 pg/μL (3 × 10² copies/reaction) and ∼23.63 pg/μL (30 copies/reaction) for pork, chicken and bovine species, respectively. Our method of detection is quick, taking only an hour, and it may be useful for food administration laboratories to carry out meat species identification in raw and processed foods.     

Determination of cadmium in tableware leach solution by spectrophotometry using 2,6-dimethylphenyldiazoaminobenzene

A sensitive and selective spectrophotometric method has been developed for determination of trace cadmium in tableware leach solution, the method based on the reaction of cadmium(II) with new reagent 2,6-dimethylphenyldiazoaminobenzene (DMPDAAB). In 0.2 mol l⁻¹ ammonia medium, DMPDAAB reacts with cadmium(II) to form 1:3 red complex with a maximum absorption peak at 523 nm. The apparent molar absorption coefficient of the complex and Sandell’s sensitivity were 2.27 × 10⁵ l mol⁻¹ cm⁻¹ and 0.495 ng cm⁻², respectively. The detection limit for cadmium and relative standard deviation were found to be 0.18 ng/g and 1.06%, respectively. Under optimal conditions, the reaction can complete instantly and absorbance of the complex remain stable for 12 h at least. Absorbance of the complex at 523 nm obey Beer’s law in the cadmium(II) range of 0–0.48 μg/ml. Moreover, we also studied the effect of foreign ions on the determination of cadmium in detail, the results showed the method has excellent selectivity, it has been applied to determine cadmium in tableware leach solution satisfactorily.     

Risk assessment for listeriosis in consumers of Parma and San Daniele hams

Following the detection of Listeria monocytogenes in samples of dry cured ham imported in the USA from Italy, the Italian Ministry of Health planned a risk assessment for listeriosis in ham consumers. The risk assessment was performed according to international guidelines set by FAO and WHO. Expected incidence of illness was 4.7 × 10⁻¹⁰ cases per serving in the case of normal adult population, 6.1 × 10⁻⁷ in the case of organ transplanted patients, the most susceptible risk sub-population. Due to the low value of water activity even in the deeper parts of the ham, bacterial growth had a very slight effect on the probability of illness.