Pesticide residues in Brassica vegetables and exposure assessment of consumers

The presence of pesticide residues in Brassica vegetables (365 samples) produced in north-eastern Poland (2006-2009) was determined and their health risks assessed. The analytical procedure was developed to examine of 130 pesticides of different chemical classes (chloroorganic, phosphoroorganic, carbamates, strobilurines, neonicotinoids, amides, pyrimidines, benzimidazoles, imidazoles and triazoles) in broccoli, Brussels sprouts, cauliflower, head and Chinese cabbage. Pesticides were extracted using matrix solid phase dispersion (MSPD) and analyzed by gas chromatography (GC) with dual detection system: electron capture (ECD) and nitrogen-phosphorus (NPD). Linearity (R² ≥ 0.997) was good over the concentration range from 2.5 to 0.001 mg/kg for all the pesticides, and instrumental detection limits ranged from 0.001 to 0.01 mg/kg. Mean recoveries for vegetables spiked at three fortification levels (0.001-2.5 mg/kg) ranged from 70.07 to 118.90%. Relative standard deviations ranged from 0.15 to 8.58%, except: dicofol, pyridaben (acaricides), dichloran (fungicide), isofenphos, triasophos (insecticides) where mean recoveries were above 120% (122.2-127%) and also dichlofluanid, tecnazene (fungicides), dichlobenil (herbicide), endosulfan-sulfate, phorate, phosmet (insecticides) with mean recoveries below 70% (42.83-69.1%). The method used to monitor pesticide residues in vegetables. Fifteen different pesticides (insecticides mainly) were detected in 118 samples (32%), while multiple pesticides (more than one pesticide residue) in about 4% samples. Chlorpyrifos and cypermethrin were the most commonly detected pesticides. Chlorpyrifos was present in 27.4% items and ranged from 0.005 to 1.51 mg/kg, while cypermethrin were detected in 3.3% samples and ranged from 0.02 to 0.19 mg/kg. Thirty-three (9%) samples exceeded the maximum residue levels (MRLs). The dietary intake of residues of some pesticides can pose acute hazards. Data obtained were then used for estimating the potential health risks associated with the exposures to these pesticides. The estimated daily intakes (EDIs) ranged from 0.005% of the ADI (acceptable daily intake) for fenhexamid to 4.454% of the ADI for diazinon. Combine cumulative exposure for chlorpyrifos detected on Brassica were 0.777% of ADI. The results show that occurrence of pesticide residues in Brassica vegetables from this region could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring and tighter regulation of pesticide residues in vegetables is recommended.     

Microbiological quality of fresh vegetables and fruits sold in Singapore

The aim of this study was to characterise the microbiological quality of selected common fresh vegetables and fruits commercially sold in Singapore in order to provide insight into any potential health hazards associated with consumption of these commodities. A total of 125 samples, collected from major supermarkets and local markets, were tested for aerobic mesophilic and psychrotrophic bacterial counts. One hundred samples were analysed for enumeration of yeasts and moulds, enumeration of coliforms and detection of Escherichia coli O157:H7 and Salmonella spp. Aerobic mesophilic counts ranged from 1.6 to 9.1 log cfu/g, with the lowest and the highest counts recorded for orange and bean sprouts, respectively. The highest level of coliforms was found in bean sprouts and fresh-cut salad, with 50% of samples containing more than 5 log cfu/g. Like coliform counts, the highest counts of yeasts and moulds were obtained in bean sprouts and fresh-cut salads. Fresh-cut salads also had the highest mean psychrotrophic plate count of 4.9 log cfu/g. Although no E. coli O157:H7 or Salmonella spp. was detected in the fruits and vegetables analysed in this study, high bacterial counts, especially in bean sprouts and fresh-cut salad, imply that effective control measures should be implemented to improve the microbiological quality of fresh produce sold in Singapore.     

Determination of polycyclic aromatic hydrocarbons in grilled meat

Polycyclic aromatic hydrocarbons (PAHs) are primarily formed as a result of thermal treatment of food, especially grilling or barbecuing. In this study nine types of Malaysian popular grilled meat dishes were analyzed for toxic PAHs, i.e. fluoranthene, benzo(b)fluoranthene and benzo(a)pyrene using HPLC-FD. The differences in PAH concentrations among (charcoal, gas and oven grilling) were found to be significant (p < 0.05), ranging from 3.51 to 106 ng/g. Fluoranthene was found in all samples; the highest concentration of total PAHs was 132 ng/g found in beef satay and the lowest was 3.51 ng/g in oven grilled chicken.     

Influence of different smoke generation methods on the contents of polycyclic aromatic hydrocarbons (PAH) and phenolic substances in Frankfurter-type sausages

The contents of polycyclic aromatic hydrocarbons (15 + 1 EU priority PAH) and phenolic substances (guaiacol, 4-methylguaiacol, syringol, eugenol, and trans-isoeugenol) in smoked Frankfurter-type sausages were investigated depending on the smoke generation method applied in a total of 63 smoking experiments. The smoke was generated by smouldering with different air supplies (smouldering smoke), by leading overheated steam through wood chips (steam smoke), by friction of a log (friction smoke), and by heating plates (touch smoke). The type of smoke generator had a noticeable influence on the contents of PAH and phenolic compounds. The highest mean content of PAH4 (2.6 μg/kg) was observed for sausages when intensive smouldering smoke was applied, the lowest (0.3 μg/kg) in friction-smoked sausages. The highest mean sum content of the five phenolic compounds was observed for sausages smoked with steam smoke (45 mg/kg) whereas the contents in friction- (15 mg/kg) and touch- (18 mg/kg) smoked products were relatively low.     

Phytochemical composition and antimicrobial properties of four varieties of Brassica oleracea sprouts

Brassica sprouts are within the most common and most widespread sprout varieties in the market, attracting consumers looking for a healthy and convenient food source of beneficial phytochemicals. In this study, four different varieties of Brassica oleracea sprouts (red cabbage, broccoli, Galega kale and Penca cabbage) were grown under different light exposure conditions and during different periods of germination to investigate the influence of these factors on their phytochemical composition. The presence of phenolic compounds and the organic acids profile of each variety was analyzed by HPLC-DAD methods, being also studied the potential antimicrobial activity of the brassica sprouts and how that could be correlated to their phytochemical composition. All samples revealed a predominance of hydroxycinnamic acids in their phenolic profile that ranged from 213 μg·g⁻¹ in broccoli to 252 μg·g⁻¹(dry weight basis) in Penca cabbage sprouts. Regarding their organic acids determination, each variety showed a characteristic profile, sharing a predominance of citric (67%), malic (19%) and oxalic (13%) acids in their composition. The organic acids content was also significantly (p < 0.05) influenced by the sprouting light conditions and duration. All sprout extracts revealed a potential antimicrobial activity of these brassica varieties against some of the most challenging foodborne pathogens. The best antimicrobial activities were found in the red cabbage and broccoli extracts, showing also a strong correlation with the organic acids found in the sprouts composition.     

High contents of cadmium,lead, zinc and copper in popular fishery products sold in Turkish supermarkets

Selected toxic (cadmium, lead) and essential (zinc and copper) trace metals were determined by means of differential pulse stripping anodic voltammetry (DPSAV) in some different brands and kinds of fishery products purchased from the popular supermarkets of Turkey. Among the fishery products, the highest concentration of cadmium, lead, zinc and copper were found in the frozen anchovy (494.2 μg/kg, 314.2 μg/kg, 566 mg/kg, 45.7 mg/kg, respectively). While the canned anchovy fillet had the lowest cadmium (25.1 μg/kg), zinc (33.8 mg/kg) and copper (7.1 mg/kg) concentrations, canned tuna fish (Brand A) had the lowest lead (76.1 μg/kg). The concentrations of all toxic and essential elements in the selected products were high and often exceeded legal limits set by health authorities. Therefore these products must be monitored more often.     

Impact of high intensity pulsed electric fields or heat treatments on the fatty acid and mineral profiles of a fruit juice–soymilk beverage during storage

Effects of high intensity pulsed electric field (HIPEF) (35 kV/cm with 4 μs bipolar pulses at 200 Hz for 800 and 1400 μs) or thermal (90 °C for 60 s) treatments on fatty acid and mineral profiles of a fruit juice-soymilk (FJ–SM) beverage during storage (56 days) at 4 °C were evaluated, having the just prepared beverage as a reference. Linoleic, oleic, linolenic, palmitic and stearic acids were found at highest concentration in the FJ–SM beverages; whereas, Ca and Mg were identified as the most abundant minerals, irrespectively of the treatment applied. Initial concentration of most fatty acids and minerals was not affected by HIPEF or thermal processes; only elaidic and linoleic acid concentration decreased after HIPEF or heat treatments, and Fe and Zn content was significantly enhanced in HIPEF beverages. Along the storage, total fatty acid content showed a significant increase in untreated and treated beverages; whereas minerals remained highly stable. Nevertheless, HIPEF beverages always showed higher concentration of fatty acids and minerals than those heat processed. Hence, HIPEF could be a potential alternative to obtain FJ–SM beverages with a long shelf-life and elevated amounts of health related compounds.     

Investigation of the contents of biogenic amines and some food safety parameters of various commercially salted fish products

Seventy-eight salted fish products originating from Turkey and European countries were analyzed for their content of biogenic amines (BA), water activity (a_w), salt and moisture, and their microbiological counts. About 10% of the samples exceeded regulated histamine levels established by the FDA and/or EU authorities. The highest histamine value was found for brined anchovy as 422 ppm. Among the other BAs, the highest level was obtained for tyramine as 524 ppm. The low a_w (<0.9) values were obtained with samples containing water phase salt (%WPS) content over 20%. Brined and dry salted products had higher %WPS than lakerda, which is a Turkish and Greek salted fish product. Despite of salt used as preservative agent in fish processing, it is found that salting alone is not enough to guarantee low levels of histamine and other BAs. This study indicated that commercial salted fish products, particularly lakerda, may still present health risk for BAs depending on processing technique, handling and storage conditions of raw material, and during processing. Therefore, processors and regulatory bodies are advised to re-evaluate their productions for safe handling measures.     

Corrosion inhibition efficiency of some hydrophobically modified chitosan surfactants in relation to their surface active properties

This work deals with surface activity and corrosion inhibition efficiency of the natural polymer chitosan and its hydrophobically modified derivatives (eight polymeric compounds). Chitosan was found to be inactive at interfaces but the hydrophobic modification using different aliphatic and aromatic substituents renders the products surface active polymers. From the obtained data it was found that the surface active properties increased by increasing the hydrophobic character of these polymers.Chitosan and its based surfactants were investigated as corrosion inhibitors for carbon steel in 1 M HCl solution using the potentiodynamic polarization method. The resulted corrosion inhibition efficiency situated between 67.56% and 93.23% at 250 ppm and 25 °C. The inhibition efficiency was discussed on the light of surface active properties and the chemical structure of the used derivatives. The quantum chemical calculations were performed for some chitosan derivatives. The charge density distribution, highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and dipole moment were considered.     

Fate of Listeria monocytogenes and Escherichia coli O157:H7 in the presence of natural background microbiota on conventional and organic lettuce

Foodborne illnesses due to the consumption of contaminated raw vegetables is a continuing food safety concern. The limited efficacy of chlorine products to disinfect in fresh-cut industries, has led to study other methods or strategies to improve the safety of processed fresh-cut products. It has been reported that the presence of competing microorganisms on the surfaces of fresh produce can contribute to the reduction of pathogens. The aim of this study was to evaluate the interactions between the natural background microbiota of shredded conventional and organic lettuce and Listeria monocytogenes and Escherichia coli O157:H7. The effect of different initial load of background microbiota (‘low’, ‘medium’ and ‘high’) was tested for its ability to reduce L. monocytogenes and E. coli O157:H7 populations on shredded lettuce during storage at 10 ± 1 °C for 8 days. After the different pre-conditioning steps in order to obtain different initial loads of microbiota, in general, we observed that varying its size had no effect on L. monocytogenes and E. coli O157:H7 survival/growth during the storage period. Only differences on the survival/growth of L. monocytogenes and E. coli O157:H7 inoculated onto organic and conventional lettuce, respectively at the end of storage period at 10 °C were found. These results highlight the necessity for corrective measures to avoid contamination of fresh-cut vegetables with foodborne pathogens.     

Efficacy of aqueous chlorine dioxide and fumaric acid for inactivating pre-existing microorganisms and Escherichia coli O157:H7, Salmonella typhimurium,and Listeria monocytogenes on broccoli sprouts

The combined effect of aqueous chlorine dioxide (ClO₂) and fumaric acid as a chemical treatment to inactivate pre-existing microorganisms was evaluated using broccoli sprouts. Broccoli sprouts were treated with distilled water, 50 ppm ClO₂, 0.5% fumaric acid, and a combination of 0.5% fumaric acid and 50 ppm ClO₂. Treatment with 50 ppm ClO₂ and 0.5% fumaric acid reduced the initial populations of total aerobic bacteria, yeasts and molds, and coliforms in broccoli sprouts by 2.70, 2.46, and 1.71 log CFU/g, respectively. In addition, the combined treatment of 50 ppm ClO₂ and 0.5% fumaric acid reduced the initial populations of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes inoculated on broccoli sprouts by 2.39, 2.74, and 2.65 log CFU/g, respectively, compared to the control. These results suggest that the combination of aqueous ClO₂ and fumaric acid can be useful as a hurdle for extending the shelf life of broccoli sprouts during storage.     

Open-refrigerated retail display case temperature profile and its impact on product quality and microbiota of stored baby spinach

Maintaining proper storage temperature is critical for ensuring the quality and safety of fresh-cut products. The US Food and Drug Administration Food Code recommend that packaged fresh-cut leafy green vegetables be kept no warmer than 5 °C at all times to ensure food safety. Substantial temperature variations, however, within the widely used open refrigerated display cases used in retail stores are known to present the technical challenge of complying with this federal guidance for industry. This study determined the extent of the spatial and temporal temperature variations within two commercial open-refrigerated display cases under different operating conditions, and their impact on the quality and microbial growth of packaged baby spinach products. The packaged products were received within 2 d of commercial processing and temperature data loggers were placed inside-and-outside of each bag. All bags were immediately loaded in the display cases and the overall visual quality, tissue electrolyte leakage, total aerobic mesophilic bacteria and psychrotrophic bacteria were evaluated for each bag. Results from this study showed that the temperature variation in the cases was dependent on spatial location, thermostat setting, and defrost cycle interval and duration of defrost. The largest temperature differentials were found for samples located in the front and back rows of the display cases. Samples located in the front rows had the highest temperature due to heat penetration from the surrounding ambient environment, while those in the back were damaged as temperatures fell below freezing. These products received low quality scores and had higher tissue electrolyte leakage. In order to reduce the large temperature variations in the display cases, insulating foam boards were installed which significantly (P < 0.05) decreased the temperature variation by 3.5 °C and enabled samples in the front rows of the cases to remain less than 5 °C as recommended by the FDA. These results suggest that the quality and safety of packaged ready-to-eat spinach at retail will benefit from improvements in open refrigerated case design or the utilization of insulation, doors or curtains.     

Nitrite level of pickled vegetables in Northeast China

Nitrite is commonly present in pickled vegetables. Nitrite has been proven to have adverse effects on health, including changing the normal form of hemoglobin and the formation of carcinogenic nitrosamines. The aim of our study was to determine the levels of nitrite in pickled vegetable samples consumed in Harbin, China. In this study, 218 samples of pickled turnip (PT) (n = 42, packaged (PK) = 19; unpackaged (UPK) = 23), pickled tuber mustard (PTM) (n = 44, PK = 23; UPK = 21), pickled cucumber (PCC) (n = 48, PK = 25; UPK = 23), and pickled cabbage (PCB) (n = 84, PK = 39; UPK = 45) were analyzed between October 2011 and December 2011, using colorimetric nitrite assay based on the Griess reaction. A nitrite level of <5 mg/kg was normally predominant in 147 (67%) samples of the investigated pickled vegetables, ranging from 0.01 mg/kg to 42.03 mg/kg, while a nitrite level of >20 mg/kg was detected in 9 (4%) samples. The overall nitrite content was 4.02 ± 0.62 mg/kg for PT, 4.52 ± 1.07 mg/kg for PTM, 3.91 ± 0.69 mg/kg for PCC, and 4.86 ± 0.80 mg/kg for PCB. The content of nitrite in unpackaged pickled vegetables (PT, 5.47 ± 0.89; PTM, 6.84 ± 2.02; PCC, 5.32 ± 1.27; PCB, 6.41 ± 1.28; and total, 6.08 ± 0.71 mg/kg) was significantly higher than those in packaged products (PT, 2.68 ± 0.72; PTM, 2.30 ± 0.55; PCC, 2.62 ± 0.54; PCB, 3.08 ± 0.81; and total, 2.73 ± 0.36 mg/kg) (P < 0.05). The variance in the concentration of nitrite in the pickled vegetables probably resulted from differences in quality, processing technique, and storage condition of the pickled vegetables. Our results indicated that, in China, low level nitrite is widely present in pickled vegetables. It is therefore important to assess the content of nitrite in pickled vegetables in China.     

Fumonisins and their masked forms in maize products

In recent years many papers on masked mycotoxins in maize-based products appeared, including reports on fumonisins capable to form non-covalent bonds with food macro constituents. Such so-called “hidden fumonisins” are frequently present in food at quantities higher than the free forms. The aim of this work was to assess levels of free and total (free + hidden) fumonisins (B₁, B₂ and B₃) in 88 maize products available on the Polish retail market. Isotope dilution ion trap mass spectrometery coupled to a high performance liquid chromatography was used. 57% of all tested samples contained free fumonisins at concentrations above our limit of quantification LOQ (mean 390 ± 676 μg/kg). More than 77% of the samples contained free + hidden fumonisins at concentrations above LOQ (mean 574 ± 1177 μg/kg). The highest mean fumonisins concentrations 1006 ± 1131 μg/kg, 1651 ± 2317 μg/kg, respectively for free and free + hidden forms were observed in the group of maize snacks. The lowest fumonisin concentrations were found in maize-based starch concentrate products. None of the tested products within that group had free fumonisins concentrations above LOQ, while mean concentration of free + hidden fumonisins was as low as 82 ± 42 μg/kg. In thermally processed products like corn flakes and various snacks the hidden-to-free fumonisin concentration ratio was higher than in unprocessed products like flour, groats or raw popcorn grains.     

Seasonal study of parasitic contamination in fresh salad vegetables marketed in Shahrekord,Iran

This survey was conducted to determine the parasitic contamination in fresh salad vegetables marketed in Shahrekord, Iran. The samples composed of unwashed and pre-washed cucumber, tomato, lettuce, cabbage, pepper, carrot, mushroom, and onion were purchased from vegetable markets. It was found that the rate of parasitic contamination was significantly higher (P < 0.05) in unwashed salad vegetables [25.2% (114/453)] than in pre-washed ones [6.03% (27/448)]. The parasites detected in unwashed salad vegetables included Ascaris lumbricoides (8.17%), Cryptosporidium spp. (2.87%), Enterobius vermicularis (2.65%), Taeniid spp. (4.86%), Strongyloides spp. (1.1%), Toxocara spp. (3.97%), and Entamoeba coli (2.43%). While the parasites namely A. lumbricoides (3.57%), Cryptosporidium spp. (1.79%), and E. vermicularis (1.12%) were detected in pre-washed ones. The rate of contamination in unwashed salad vegetables obtained during summer was significantly higher (P < 0.05) than those obtained during the other seasons. Occurrence of the parasites was the highest in lettuce, followed by cabbage and carrot both in unwashed and pre-washed vegetables. The unwashed field-origin vegetables like cucumber, tomato, and pepper showed significantly higher contamination (P < 0.05) than their greenhouse-origin counterparts. The results indicate the potential hazard of unwashed and pre-washed salad vegetables in transmission of parasites to humans, and also show the importance of proper washing before preparation of salads.     

The concentration of minerals and physicochemical contaminants in conventional and organic vegetables

In this study, we performed a comparative analysis of the physical-chemical composition and pesticide residue content of lettuce, peppers, and tomatoes that were grown in organic and conventional systems. The vegetables were purchased at the Food Supply Centre of Pernambuco [Centro de Abastecimento Alimentar de Pernambuco – CEASA/PE], Pernambuco state, Brazil. The physical-chemical composition of the vegetables was determined according to the analytical procedures of the Association of Official Analytical Chemist. The minerals (Cu, Cr, Fe, K, Mn, Mg, Na, and Zn) and the heavy metals (Cd, Ni, and Pb) were assessed using atomic absorption spectrometry, and the pesticide residues were determined using a multi-residue analysis. The results were compared by means of a Student's t-test. Principal component analysis was performed to investigate the correlations between the minerals and the heavy metals. The measurements of weight, length, and width of all three of the vegetables that were assessed were higher in the conventional group. There were significant differences (p < 0.05) in the proximate composition of conventional and organic lettuces (moisture, ash and protein) and in all the parameters of conventional and organic peppers. To tomatoes there wasn't significant difference (p > 0.05). All three of the organic vegetables were higher in total dietary fibre. The composition of the minerals and heavy metals varied between all three vegetables. Contamination by pesticide residues was found in conventional peppers and organic tomatoes.     

Carotenes in processed tomato after thermal treatment

This report adds to the ongoing vivid dispute on the fate of carotenes in tomato upon thermal processing. Although many papers dealing with changes in the raw tomatoes during industrial treatment have already appeared, data on the fate of finished, processed tomato products when they are additionally heated (e.g., when used in the household) is scarce. In this study, effects of heating and storage on a commercial, double concentrated tomato purée were examined spectrophotometrically. Our results indicate that upon exposing unopened cans with double concentrated tomato purée to thermal treatments between 100 and 135 °C during specific time intervals spectral profile of lycopene remained preserved. Likewise, a slight hypsochromic shift of lycopene peak III did not occur up to 135 °C. However, significant (20%) initial loss of lycopene content was induced by thermal treatment for 20 min at 100 °C. During the more intensive treatments that followed the lycopene content was first leveling off and then slightly increased. After storage of thermally treated samples at −18 °C the content of lycopene was found to increase. All these results suggest simultaneous working of several mechanisms: possible auto-oxidation and isomerization processes of carotenes taking place, in addition to the Maillard reaction and enhanced extractability of carotenes at increased temperatures. Results acquired from hexane solutions of samples treated at temperatures of 120 and 135 °C obtained at different time points, confirmed severe isomerization in organic solvent and/or photo-oxidative degradation of lycopene.     

Prevalence and characterization of Listeria monocytogenes isolated from retail food in Henan,China

Listeria monocytogenes, an important foodborne pathogen, is the causal agent of listeriosis. In this study, a total of 954 food samples originating from raw meat, cooked meat products, seafood, and vegetables purchased from supermarkets and open-air markets in Henan province, China, were analyzed for the presence of L. monocytogenes. All L. monocytogenes isolates were subjected to serotyping, pulsed-field gel electrophoresis (PFGE), and antimicrobial resistance. The overall percentage of L. monocytogenes prevalence was 6.2% (n = 59) with the highest rate of 7.4% for cooked meat products followed by raw meat (6.7%). The isolates belonged to five serotypes (1/2a, 1/2b, 1/2c, 4b, and 4c), with serotype 1/2a being predominant (55.9%). PFGE revealed a low genetic diversity among the isolates, irrespective of their sources, suggesting that dominant clones are widespread in different food products in Henan. Resistance to cefotaxime (30.5%) and ciprofloxacin (13.5%) was most often, whereas resistance to tetracycline, trimethoprim/sulfamethoxazole, and erythromycin was observed less frequently. The presence of L. monocytogenes in food products and antimicrobial resistance among the isolates represents a potential public health risk. Our results indicate that effective hygienic measures and bacteriological controls are necessary in China to reduce the contamination of retail food samples by L. monocytogenes.     

Evaluation of minimally processed salads commercialized in Portugal

During the last decades food borne outbreaks associated with consumption of raw vegetables have been increasing and green leafy vegetables seem to be the most frequently implicated products.In order to determine the microbial quality and the incidence of the major food borne pathogens in Minimally Processed (MP) salads commercialized in Portugal, a survey was conducted in Lisbon Retail Markets, from July 2007 to August 2008, to determine microbial contamination loads and identify potential pathogenic bacteria.A total of 151 samples were purchased from 2 supermarkets: 38 romaine lettuce, 12 various spinach and 101 mixed salads with three or four different ingredients. The samples were tested for aerobic psychotropic micro-organisms (APM), Enterobacteriaceae, Escherichia coli, Listeria spp., presumptive Bacillus cereus, Aeromonas hydrophila and Clostridium perfringens counts as well as for presence of Salmonella spp., Listeria monocytogenes and E. coli O157. Samples were also evaluated for taste quality.The results showed that APM counts of romaine lettuce and mixed salads had a similar median, respectively, 6.2 and 6.5 log cfu/g and mixed spinach had the highest one (7.6 log cfu/g). The median value found for Enterobacteriaceae was 5.44 log cfu/g. Only four samples showed positive result for E. coli (2.65%) but just one (0.8%) had a slightly higher load of contamination. Although the percentage and levels of contamination loads were low, these mustn’t be ignored, for the reason that the strains in three of the samples belong to VTEC group (1.99%). E. coli O157, Salmonella spp. and C. perfringens weren’t detected in any sample. For the enumeration of Listeria spp., two samples (1.32%) had presence of Listeria innocua and L. monocytogenes had an incidence of 0.66%. A. hydrophila was identified in 11 samples (7.28%), and in 8 of them with considerable counts (>10⁵). Contamination with B. cereus was found in 22.7% of samples analyzed, though in small numbers, which doesn’t represent a major concern to food safety. All isolated strains were assessed for its potential toxin production and it was found that 40% of these strains had this ability. Results from sensory panel showed organoleptic differences in salads during its shelf-life period.     

Potential bio-activity of whey fermented extract as sanitizer of organic grown lettuce

Consumption of vegetables is increasing due to demand for healthy products in peoples' diets. To reduce microbial contamination and maintain freshness, industrial processes in Portugal rely on minimally processing of vegetables with hypochlorite as sanitizer. Formation of toxic chlorine derivatives has raised concern restrictions to its use and alternatives with whey permeate as a disinfection agent has been attempted. The aim of this work was to evaluate the bio potential of fermented cheese whey, for use on disinfection of minimally processed lettuce organically grown.Assays were made with whey obtained from inoculated milk during cheese processing, fermented for 120 h at 37 °C, after which, among other carbohydrates, lactic acid was measured by HPLC, giving average yields of 18 g L⁻¹.The sanitizing effect of whey, undiluted, 75 and 50% solutions, was compared with 110 ppm sodium hypochlorite, after rinsing. Aerobic Microorganisms (AM), Psychrotrophic Microorganisms (PM) and Enterobacteriaceae (ENT), were used as indicators for hygiene quality. For a level of significance of P < 0.05, the hygiene quality standards of lettuce samples, were better using 75% whey solution (AM 6.62, PM 7.48 cfu g⁻¹), than using sodium hypochlorite (AM 7.48, PM 8.15 cfu g⁻¹), for the 7 days of shelf life studied. Evaluation of Enterobacteriaceae showed significant differences after 3 days, between water (ENT 4.98 cfu g⁻¹) sodium hypochlorite (ENT 4.81 cfu g⁻¹) and 75% solution of whey (ENT 4.63 cfu g⁻¹).Considering the actual limitations imposed to chlorine sanitation, these results point a good alternative to the food industry, especially for organic fresh vegetables, which are chemical free brands.