Levels of polychlorinated dibenzo-p-dioxins,dibenzo-p-furans and polychlorinated biphenyls in farmed sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) from Turkey

Farmed European sea bass and Gilthead sea bream were obtained from four different fish farms in Turkey during 2008–2009, for determination of 17 2,3,7,8-Cl-substituted PCDDs and PCDFs, and coplanar and indicator PCBs.Concentrations of ∑PCDD/Fs and DL-PCBs, as TEQ, in fish samples, ranged from 0.14 to 0.70 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight and from 0.46 to 4.51 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight, respectively. The concentrations of total indicator PCBs in fish samples ranged from 3.1 ng g⁻¹ to 22.1 ng g⁻¹ wet weight. Concentrations of PCDD/Fs and DL-PCBs were below the EU regulation (EC No. 1881/2006) limits.     

Quality assessment of Mediterranean horse mackerel (Trachurus mediterraneus) and blue jack mackerel (Trachurus picturatus) during storage in ice

Sensory, physicochemical and microbiological analyses were carried out on Mediterranean horse mackerel and blue jack mackerel in order to determine quality changes during storage in ice. Sensory results indicated that whole Mediterranean horse mackerel and blue jack mackerel used in this trial had a shelf-life of 10 and 7 days, respectively. Fishtester and Fishchecker measurements showed that the quality of blue jack mackerel had deteriorated more rapidly. Fishtester values of the blue jack mackerel and the Mediterranean horse mackerel were reduced from 59 ± 10.1 to 14.8 ± 2.8 and from 85.3 ± 13.2 to 25.6 ± 7.8, respectively during the storage time. Fishchecker gave red sign (unfit for consumption) for first time on day 7 and day 6 in Mediterranean horse mackerel and blue jack mackerel, respectively. The pH of Mediterranean horse mackerel muscle was consistently lower than the pH of blue jack mackerel muscle during the storage period. The pH values of both species muscle increased gradually with time and pH value equal to 7 had almost coincided with the end of shelf-life. Bacterial loads in both fish species muscle remained rather low prior to day 10 (<6 log₁₀ cfu/g). The longer shelf-life of Mediterranean horse mackerel as determined by sensory evaluation was not reflected in microbiological results suggesting that the difference was due to lower rate of autolysis rather than to reduced microbial activity.     

Effect of isothiocyanates from horseradish (Armoracia rusticana) on the quality and shelf life of tofu

The effects of isothiocyanates (ITCs) on microbiological, physicochemical, and sensory properties were investigated in tofu on days 0, 2, 4, 6, 8, and 10 of storage at 10 °C. When compared to the control (8.14 log CFU/g), the 200 ppm of ITCs (4.40 log CFU/g) effectively retarded the growth of microflora in tofu after 10 days of storage. The initial pH slightly declined after 10 days of storage, ranging between 5.81 and 6.14. The control showed significantly higher acid values over storage. Compared to the control, the preference to sensory attributes (color, taste, odor, chewiness, and over acceptance) of ITC-treated samples was highly rated after 10 days of storage. The ITCs can be used as an alternative for extending the shelf life and improving the safety of tofu.     

Microbiological changes in farm reared freshwater prawn (Macrobrachium rosenbergii de Man) in ice

The microbiological changes in farm reared freshwater prawn (Macrobrachium rosenbergii de Man) during ice storage were studied. A total of 156 bacterial cultures from fresh and ice-stored farmed freshwater prawn were isolated and characterized. Total aerobic, mesophilic and psychrotrophic counts and hydrogen sulphide producing bacterial counts were determined. The total aerobic counts at 20 and 37 °C on fresh prawn was in the range of 4–5 log₁₀ cfu g⁻¹. Aerobic counts on M. rosenbergii at 20 °C and 7 °C exceeded 10⁷ cfu g⁻¹ by the end of storage, of which 40–52% were H₂S producers. Gram-negative bacteria constituted 73% of the total flora of fresh prawn and Enterobacteriaceae and Aeromonadaceae dominated. After 19 days of iced storage, more than 80% of the bacterial flora of prawn were Gram-negative. Pseudomonas, Aeromonas hydrophila, A. veronii boivar sobria and Shewanella putrefaciens were identified as the dominant spoilage organisms of farm reared M. rosenbergii stored in ice. This study confirms that freshwater prawn carry significant numbers of motile aeromonads capable of growth at low temperature. The results of the study indicated that the shelf-life of freshwater prawn as determined by microbiological data is 12–16 days. Immediate icing of harvested M. rosenbergii is essential to improve the microbiological stability.     

Effects of pulsed electric field treatments on quality of peanut oil

The effects of pulsed electric fields (PEF) treatment on physicochemical properties of peanut oil were investigated in this paper. Compositions of fatty acid, acid value (AV), peroxide value (PV), as well as carbonyl group value (CGV) of various PEF-treated peanut oil samples with different storage time were determined by GC/MS and AOCS standard methods. GC/MS analysis showed that little change of the oil composition was observed after PEF treatment. However, after being treated by various PEF treatments and stored at 40 °C for 100 days, the biggest increment of AV was 0.69 mg g⁻¹, which was lower than that of untreated peanut oil (0.79 mg g⁻¹). The PV significantly increased from 4.8 meq kg⁻¹ untreated oil to 11.5 meq kg⁻¹ PEF treated oil (50 kV cm⁻¹). And the increase extent of CGV of oil samples during the 100 d’ storage period was decreased with increasing electric field strength. During the storage period, the differences of AV, PV, and CGV of PEF-treated sample during storage period were less than that of untreated oil, which implied that the PEF treatment could restrain the speed of lipid oxidation reaction thus extending the shelf-life of oil rich products.     

Seasonal variation in the chemical composition and microbiological condition of Mediterranean horse mackerel (Trachurus mediterraneus) muscle from the North Aegean Sea (Greece)

The aim of this work was to determine the chemical composition and microbiological quality of Mediterranean horse mackerel (Trachurus mediterraneus) muscle during the year and the consequent advantages or disadvantages in processing the raw material. A total of 180 samples were examined (15 samples per month) during two years (November 2001–November 2003). Fish were caught in the coastal waters of Chalkidiki peninsula (Northern Greece). Proximate composition of the muscle during the year resulted in: water 76.8 ± 1.39%, proteins 20.3 ± 0.68%, fat 1.3 ± 1.08% and ash 1.5 ± 0.08%. In March, April and May an increase in fat content of the muscle (2.5%, 2.8% and 2.1%, respectively) and a decrease in water content of the muscle (below 75.9%) were observed. On the contrary, fat content showed a decrease in September and October (0.4% and 0.6%, respectively), while water content of the muscle increased during these months (78.2% and 77.6%, respectively). The protein content of the muscle remained at high values, while the ash content was almost constant during the year. The mean value of muscle pH was 6.38 ± 0.16; extreme values (<6 or >7) of muscle pH were not observed. Total Viable Bacteria, Shewanella putrefaciens and Pseudomonas spp. were used as microbial indices to evaluate the microbiological quality of the muscle. Mean counts of Total Viable Bacteria, S. putrefaciens and Pseudomonas spp. during the year were: 4.01 ± 0.38 log₁₀ cfu/g, 2.37 ± 0.43 log₁₀ cfu/g and 3.34 ± 0.27 log₁₀ cfu/g, respectively. The variations of the values within seasons are minimal and significant homogeneity in the chemical composition and microbiological quality of Mediterranean horse mackerel muscle is observed. This is an important advantage in processing of the raw material.     

Development of Quality Index Method (QIM) scheme for spiny lobster (Panulirus argus,Latreille, 1804) stored in ice

The objective of this study was to evaluate the freshness of spiny lobster (Panulirus argus) stored on ice up to 18 days. Changes during storage were observed with sensory evaluation (Quality Index Method – QIM), pH, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), and microbiological analyses (total mesophilic and psychrotrophic count). The maximum shelf life of spiny lobster stored in flake ice at 1 ± 0.2 °C was determined with loss of freshness (sensorial, physico-chemical and microbiological evaluations). High correlation R² = 0.922 between Quality Index (QI) and storage time at 1 °C was verified. QI ranged from zero (maximum freshness) to 15 (total loss of freshness) and reached the acceptable limit for consumption (QI = 9.54), which corresponds to a period of 10 days. The microbiological results showed an increase of psychrotrophic count along the storage time. TVB-N ranged from 5.23 to 20.31 mg 100 g⁻¹, TMA-N from 1.07 to 5.72 mg 100⁻¹ and pH from 6.91 to 7.19 in the first and 18th day of storage, respectively. It is suggested that spiny lobster has to be fresh and acceptable for consumption by cooling up to 10 days.     

Evaluation of 10 pesticide residues in oranges and tangerines from Valencia (Spain)

One hundred and sixteen orange and tangerine samples from an agricultural cooperative of the Valencian Community (Spain) were analyzed for bitertanol, carbendazim, hexythiazox, imazalil, imidacloprid, methidathion, methiocarb, pyriproxyfen, thiabendazole, and trichlorfon by liquid chromatography–mass spectrometry (LC–MS) after a conventional multiresidue extraction procedure. Of 52 samples that contained pesticide residues, carbendazim was detected in 27 (51.9%) in the concentration range of 0.02–0.04 mg kg⁻¹, hexythiazox in 22 (42.3%) in the concentration range of 0.02–0.05 mg kg⁻¹, imazalil in 8 (15.0%) in the concentration range of 0.02–1.2 mg kg⁻¹, imidacloprid in 5 (9.6%) in a concentration range of 0.02–0.07 mg kg⁻¹ methidathion in 17 (32.6%) in the concentration range of 0.06–1.3 mg kg⁻¹, and methiocarb in 1 (2%) at a concentration of 0.02 mg kg⁻¹. Bitertanol, pyriproxyfen, thiabendazole and trichlorfon were not detected in any sample. Although 19 samples contained residues of two or three of the studied pesticides, no sample exceeded the European Maximum Residue Limits (MRLs). The results show that despite a high occurrence of pesticide residues in oranges and tangerines from Valencian Community, the contamination levels of these residues could not be considered a serious public health problem according to European Union (EU) regulations.     

Effects of gamma irradiation on the microbiological,nutritional, and sensory properties of fresh vegetable juice

The radiation pasteurization process was performed to improve the microbiological quality of fresh vegetable juice. Carrot and kale juice were irradiated and their microbiological, nutritional, and sensory properties were evaluated. The contaminating bacteria in the juices before irradiation ranged from 10⁶ to 10⁷ CFU/ml. All the aerobic and coliform bacteria in the carrot juice were eliminated by irradiation at a dose of 3 kGy, whereas about 10² CFU/ml of the bacteria survived in the kale juice irradiated at up to 5 kGy. However, the cells that survived from irradiation in the kale juice did not grow, whereas those of the non-irradiated samples reached 10⁹ CFU/ml after 3 days of storage at 10 °C. Amino acids were stable at up to 5 kGy of an irradiation. Radiation resulted in a dose-dependent reduction of the ascorbic acid content. However, the contents of the total ascorbic acid, including dehydroascorbic acid, were stable at up to 3 kGy of an irradiation. The sensory evaluation results immediately after irradiation were not different in any of the samples. At a 3-day storage, the sensory quality of the irradiated juice was adequate, while the quality of the non-irradiated control was deteriorated.     

Antimicrobial activity of clove (Syzgium aromaticum) oil in inhibiting Listeria monocytogenes on chicken frankfurters

The ability of Listeria monocytogenes to survive and grow at refrigeration temperature in some ready to eat (RTE) poultry products is a public health concern. The inhibitory effect of clove oil (1% and 2%, v/w) applied to the surface of RTE chicken frankfurters was determined on seven strains of L. monocytogenes inoculated at low (10²–10³ cfu/g) or high cell numbers (10⁴–10⁶ cfu/g), and stored at 5 °C for 2 weeks or at 15 °C for 1 week. All strains of L. monocytogenes survived and grew on control frankfurters at 5 °C and 15 °C but growth was inhibited under both storage conditions in the presence of either 1% or 2% clove oil. Depending on the sensory considerations, the addition of clove oil to frankfurters may be an effective strategy to control L. monocytogenes in chicken frankfurters.     

Microbiological evaluation of an edible antimicrobial coating on minimally processed carrots

This work aimed to develop an edible antimicrobial coating based on a starch–chitosan matrix to evaluate its effect on minimally processed carrot by means of microbiological analyses. Coatings based on 4% yam starch (w/w) + 2% glycerol (w/w) and coatings based on 4% yam starch (w/w) + 2% glycerol (w/w) + chitosan in 0.5% and 1.5% concentrations were prepared. Samples of minimally processed carrot slices were immersed into these coatings. All the samples were placed in expanded polystyrene trays, wrapped in polyvinylchloride film and stored at 10 °C/15 days. During storage, all the samples had counting <100 CFU/g for Staphylococcus aureus and <3 MPN/g for Escherichia coli. Starch + 0.5% chitosan coating controlled the growth of mesophilic aerobes, yeasts and molds and psychrotrophs during the first five days of storage, ultimately presenting reductions of only 0.64, 0.11 and 0.16 log cycles, respectively, compared to the control. Starch + 1.5% chitosan coated samples showed reductions in mesophilic aerobes, mold and yeast and psychrotrophic counting of 1.34, 2.50 and 1.30 log cycles, respectively, compared to the control. The presence of 1.5% chitosan in the coatings inhibited the growth of total coliforms and lactic acid bacteria throughout the storage period. The use of edible antimicrobial yam starch and chitosan coating is a viable alternative for controlling microbiological growth in minimally processed carrot.     

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.     

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.     

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.     

Pentocin 31-1, a novel meat-borne bacteriocin and its application as biopreservative in chill-stored tray-packaged pork meat

Pentocin 31-1 was produced by Lactobacillus pentosus 31-1, isolated from the traditional China fermented Xuan-Wei Ham. In this work, study on its application as biopreservative in chill-stored nonvacuum-tray-packaged pork meat was carried out. Pentocin 31-1 was prepared by pH-adsorption in 5 l stainless steel fermentor. Each 200 ml semi-purified bacteriocin was obtained from one fermentation, and the specific activity was 1280 AU/ml. The effects of pentocin 31-1 on microbiological counts, physicochemical change and sensory quality of chilled pork in the period of preservation at 4 °C was investigated. Results showed that pentocin 31-1 could substantially inhibit the accumulation of VBN and generally suppress the growth of microflora, especially Listeria and Pseudomonas, during chilled pork storage. Microbiological counts, physicochemical parameters and sensory characteristics of the treatments (40 AU/ml pentocin 31-1 or 75 AU/ml nisin) had exceeded the limitation of Chinese hygienic standard for fresh meat of livestock by day 15. 80 AU/ml pentocin could extend the shelf life to 15 days and the meat showed good sensory characteristics. These results suggest the potential of pentocin 31-1 as a biopreservative in tray-packaged chilled pork storage.     

Investigations on the essential oil of Lippia rugosa from Cameroon for its potential use as antifungal agent against Aspergillus flavus Link ex. Fries

Lippia rugosa essential oil was tested for its effectiveness against Aspergillus flavus on artificial growth media. The chemical composition of the oil was determined by gas chromatography–mass spectrometry (GC–MS). Geraniol (51.5%), nerol (18.6%) and geranial (10.4%) were the main components of Lippia oil. After 8 days of incubation on essential oil supplemented medium, mycelium growth of A. flavus was totally inhibited by 1000 mg l^?1 of L. rugosa essential oil. The effect of essential oil on aflatoxin B₁ synthesis was evaluated in SMKY broth. The medium supplemented with different essential oil concentrations, was inoculated with A. flavus mycelium and incubated at 25 °C. After 2, 4, 6 and 8 days, aflatoxin B₁ (AFB₁) was quantified in the supernatant using Enzyme Linked Immuno-Sorbent Assay (ELISA). Results showed that aflatoxin B₁ synthesis was inhibited by 1000 mg l^?1 of L. rugosa essential oil after 8 days of incubation. The effect of the EO on the H⁺-ATPase pumping membrane was also evaluated in the presence of several concentrations of oil (200–2000 mg l^?1) by monitoring glucose-induced acidification of the external medium. L. rugosa essential oil at the concentration of 2000 mg l^?1 completely inhibited the activity of this enzyme. These data suggest that the essential oil of L. rugosa is a fungicidal for A. flavus and its possible cellular target include the H⁺-ATPase.Results obtained in the present study indicate the possibility of exploiting Lippia rugosa essential oil in the fight against strains of A. flavus responsible for biodeterioration of stored foods products.     

Effect of orange dietary fibre,oregano essential oil and packaging conditions on shelf-life of bologna sausages

The objective of this work was to study the effect of orange dietary fibre (1%) (ODF), oregano essential oil (0.02%) (OEO) and the storage conditions (vacuum, air and modified atmosphere) on the shelf-life of bologna sausage. Samples with ODF + OEO stored in vacuum packaging showed the lowest TBA values. ODF + OEO samples stored in vacuum packaging showed the lowest aerobic and lactic acid bacteria counts. The sensory evaluation scores were similar for samples with ODF + OEO and stored either in air or vacuum packaging. Orange dietary fibre and oregano essential oil could find a use in the food industry to improve the shelf-life of meat products.     

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.     

A versatile splitless injection GC-FID method for the determination of mineral oil paraffins in vegetable oils and dried fruit

A splitless injection GC-FID method for determining mineral paraffins in food was set up. The method has been developed on vegetable oils and subsequently adjusted and applied to dried fruits, a food matrix not yet investigated from this point of view. The method avoids the saponification step foreseeing only a clean-up on silica gel SPE, and allows the quantification of mineral paraffins with a limit of quantification (LOQ) of 15 mg kg⁻¹ and a detection limit (LOD) of 5 mg kg⁻¹ in the oils. LOQ and LOD for the analysis of dried fruit samples are respectively 1.0 and 0.3 mg kg⁻¹.Eighteen samples of dried fruit were analysed (apricots, plums, raisins, coconut, dates, mango, pineapple). Two samples of apricots showed high values of contamination, 23.0 and 28.2 mg kg⁻¹ of mineral paraffins, while all the other samples contained less than 6.4 mg kg⁻¹ of mineral paraffins and in four samples mineral paraffins were undetectable.     

Microbiology of retail mung bean sprouts vended in public markets of National Capital Region,Philippines

This study is the first attempt in the Philippines to conduct a region-wide assessment of the microbiological quality of retailed mung bean sprouts. Production and vending practices of selected stakeholders were also determined. Ninety-four percent of the samples tested positive for the presence of Salmonella spp. and some samples had Coliform and Escherichia coli counts as high as 5.90 and 5.50 log₁₀ CFU · g⁻¹, respectively. The TPC, YMC and LAB were established to be as high as 11.38, 5.90 and 10.47 log₁₀CFU · g⁻¹, respectively. The poor microbiological quality of most of the tested sprouts was attributed to unhygienic sprout production and retailing practices. To improve the microbiological quality of the retailed sprouts, adherence to sprouting industry best practices is strongly recommended.