Kinetics of the ozonation of muconic acid in water

The removal of muconic acid (specifically trans-trans-butanedioc acid) with ozone from water has been studied for kinetics purposes. Concentrations of muconic acid of 4.4x10(-4)M are completely removed with ozone in less than 14 and 9 min at pH 3 and 7, respectively, and 3x10(-4)M of ozone in the gas. The positive influence of pH was due to the more reactive muconic acid dissociated form with ozone. The process can be described as a second order irreversible gas-liquid reaction developing in the moderate kinetic regime of absorption. At the experimental conditions investigated no free radical reactions are present and muconic acid is entirely oxidized by molecular ozone. Rate constants of the direct reaction between muconic acid and ozone were found to be 1.6x10(4) and 1.4x10(5)M(-1)s(1) at 20 degrees C, pH 3 and 7, respectively, according to film theory.     

Conjugated linoleic acid (CLA) and polyunsaturated fatty acids in muscle lipids of lambs from the Patagonian area of Argentina

The concentrations of fatty acids were measured in total lipids, triacyglycerol and phospholipid fractions of intramuscular fat (IMF) from the Longissimus dorsi (LD) muscle of 10 lambs reared to approximately 30kg live weight on natural pasture with their dams. Fatty acid composition was also measured in 25 (five of each) Semitendinosus (ST), Semimembranosus (SM), Rectus femoris (RF), Gluteus (GLU) and Tensor fascia latea (TFL) muscles. Intramuscular fat percentages were similar for all muscles. Aspects of the fatty-acid patterns of relevance to human nutrition tended to favor the leg muscles with lower saturated fatty acids (SFA %), n-6/n-3 fatty acid ratios (p<0.01) and higher concentrations of the conjugated linoleic acid (CLA) (p<0.05). The estimated fatty acid concentrations (mg/100g of meat) showed higher contribution of arachidonic (C20:4 n-6), eicosapentanoic (C20:5 n-3), docosapentanoic (C22:5 n-3) and docosahexanoic (C22:6 n-3) acids in leg compared to LD lipids.     

Enumeration of Enterobacteriaceae in various foods with a new automated most-probable-number method compared with petrifilm and international organization for standardization procedures

An automated most-probable-number (MPN) system (TEMPO, bioMérieux, Marcy l'Etoile, France) for enumeration of Enterobacteriaceae (EB) was compared with methods involving violet red bile glucose agar (VRBG) (International Organization for Standardization [ISO] method 21528-2) (ISO-VRBG) and Petrifilm (PF-EB). The MPN partitioning (three different volumes with 16 replicates of each) is done automatically in a disposable card. Bacterial growth is indicated by acid production from sugars, lowering the pH of the medium, and quenching the fluorescence of 4-methylumbelliferone. After incubation, the number of nonfluorescent wells is read in a separate device, and the MPN is calculated automatically. A total of 411 naturally contaminated foods were tested, and 190 were in the detection range for all methods. For these results, the mean (+/- standard deviation) counts were 2.540 +/- 1.026, 2.547 +/- 0.995, and 2.456 +/- 1.014 log CFU/g for the ISO-VRBG, PF-EB, and automated MPN methods, respectively. Mean differences were -0.084 +/- 0.460 log units for the automated MPN results compared with the ISO-VRBG and 0.007 +/- 0.450 for the PF-EB results compared with the ISO-VRBG results. The automated MPN method tends to yield lower numbers and the PF-EB method tends to yield higher numbers than does the ISO-VRBG method (difference not significant; Kruskal-Wallis test, P = 0.102). Thus, the average difference was highest between the automated MPN method and the PF-EB method (-0.091 +/- 0.512 log units). Differences between the automated MPN and ISO-VRBG results of > 1 log unit were detected in 3.4% of all samples. For 3.9% of the samples, one comparison yielded differences of < 1 log CFU/g and the other yielded > 1 but < 2 log CFU/g, which means that the differences are possibly > 1 log CFU/g. For the ISO-VRBG method, confirmation of isolates was necessary to avoid a bias due to the presence of oxidase-positive glucose-fermenting colonies. The automated MPN system yielded results comparable to those of the confirmed Enterobacteriaceae ISO-VRBG method but required only 24 h of analysis time.     

Antimicrobial activity of sub- and supercritical CO2 extracts of the green alga Dunaliella salina

The objective of this research was to evaluate the antimicrobial activity of carbon dioxide extracts of the unicellular biflagellated green alga Dunaliella salina against Escherichia coli, Staphylococcus aureus, Candida albicans, and Aspergillus niger. The effects of different extraction pressures ranging from 185 to 442 bar and extraction temperatures ranging from 9.8 to 45.2 degrees C on the extracts' composition and consequently on their antimicrobial activities were investigated. The extracts were analyzed by gas chromatography-mass spectrometry in order to identify the compounds responsible for the antimicrobial activity detected. Fourteen different volatile compounds and several fatty acids were identified. The highest antimicrobial activity was obtained using 314 bar and 9.8 degrees C. Under these conditions, the presence of an indolic derivative that had never been reported in D. salina was detected in the extract, together with polyunsaturated fatty acids and compounds related to carotene metabolism, such as beta-ionone and neophytadiene, with known antimicrobial activity.     

Survey of Salmonella contamination of raw shell eggs used in food service premises in the United Kingdom, 2005 through 2006

This survey was launched after an unusual number of Salmonella Enteritidis outbreaks associated with the use of eggs in food service premises in England and Wales. Between November 2005 and December 2006, 9,528 eggs (1,588 pooled samples of 6 eggs) were collected from 1,567 food service premises in the United Kingdom, most of which (89%) were produced in the United Kingdom. Salmonella was isolated from 6 (0.38%) pools of eggs. Of these, 5 (0.31%) were Salmonella Enteritidis, which were further characterized to phage types (PTs): PT 4 (0.19%), PT 8 (0.06%), and PT 12 (0.06%). Salmonella Mbandaka was also isolated (0.06%). Salmonella was detected from five and one of pooled eggs samples that were produced in the United Kingdom and Germany, respectively; these were from different producers. The study showed evidence of poor egg storage and handling practices in food service premises, in that 55% did not store eggs under refrigerated conditions; 20.7% of eggs had expired "best before" dates or were in use after 3 weeks of lay, indicating poor stock rotation; and 37.1% pooled eggs not intended for immediate service. Eggs are a commonly consumed food that may occasionally be contaminated with Salmonella at different rates, according to their country of origin. The food service sector needs to be aware of this continuing hazard, receive appropriate food safety and hygiene training on storage and usage of raw shell eggs, adopt appropriate control measures, and follow advice provided by national food agencies in order to reduce the risk of infection.     

Ethanolic extracts of Antrodia cinnamomea mycelia fermented at varied times and scales have differential effects on hepatoma cells and normal primary hepatocytes

Mycelia of Antrodia cinnamomea (AC), an edible fungus native to Taiwan, were produced by submerged fermentation with various fermentation times in 250 mL, 5 and 500 L fermentors and were evaluated for the effect of fermentation products on the viabilities of Hep3B and HepG2 hepatoma cells and normal primary rat hepatocytes. The results showed that the ethanolic extracts of AC mycelia (from 250 mL fermentation for 8 wk and 5 and 500 L fermentations for 4 wk) possessed high antihepatoma activity. The IC(50) of ethanolic extract of AC mycelia fermented for 8 wk in a 250 mL fermentor against Hep3B and HepG2 cells were 82.9 and 54.2 microg/mL, respectively. Furthermore, the IC(50) for Hep3B and HepG2, treated with ethanolic extract of AC mycelia fermented for 4 wk in the 5 L fermentor were 48.7 and 3.8 microg/mL, respectively. Those treated with ethanolic extract of AC mycelia fermented for 4 wk in the 500 L fermentor were 36.9 and 3.1 microg/mL, respectively. No adverse effects of all samples on normal primary rat hepatocytes were observed.     

Restored wetlands as a source of disinfection byproduct precursors

The effects of a restored wetland system in the Sacramento Valley, California on the production of dissolved organic carbon (DOC) and nitrogen (DON) and the formation potential of common disinfection byproducts (DBPs: trihalomethanes, haloacetonitriles, and chloral hydrate) were examined. Additionally, the effects of photodegradation and microbial degradation on dissolved organic matter properties and reactivitywith respect to DBP formation potential (DBP-FP) were evaluated. The wetlands increased DOC and DON concentrations by a factor of 2.2 and 1.9 times, respectively, but had little influence on the DOC and DON quality as compared to their source waters. The increase in DOC and DON concentrations increased the formation potential of all DBP species by >100%. Solar radiation and microbial degradation reduced the trihalomethane formation potential by 24 and 10%, respectively, during a 14 day incubation. In contrast, the chloral hydrate formation potential was increased by 22% after phototreatment. Results indicate that current flood-pulse management practices with a 2-3 week residence time could lead to wetlands acting as a source of DBP precursors. Enhanced DBP-FP is especially important as these wetlands contribute to a watershed that is a drinking water source for more than 23 million people.     

Application of ATP bioluminescence for evaluation of surface cleanliness of milking equipment

The ATP bioluminescence method was used to evaluate the cleanliness of milking equipment surfaces (teat cup rubbers, teat dip containers, milk receivers, and pipeline joints) in dairy farms in Galicia (northwest Spain) with parlour, pipeline tie-stall or bucket tie-stall milking systems. The cleanest surfaces were teat cup rubbers. The use of non-chlorinated water for cleaning, and of pipeline or bucket tie-stall milking systems, was associated with high ATP bioluminescence values. However, ATP bioluminescence values only explained 12% of the variability in bulk-tank bacterial count; this is attributable to the importance of other factors (notably the correct functioning of the tank cooling system) for maintenance of low bacterial count.     

Ochratoxin A and citrinin producing species of the genus Penicillium from feedstuffs

In Spain, low ochratoxin A (OTA) levels have been detected in several pork products but there is no information published about the fungi involved in this OTA contamination. It is well known that P. verrucosum is much more frequently found on cereals in countries where they occasionally have OTA problems as in North European countries compared with South Europe where levels of OTA generally seem to be lower or not detected. Much less information is available about citrinin (CIT) and CIT producing species in cereals and their by products. The aim of this study was to determine, identify and characterize the occurrence of potential OTA and CIT producing Penicillium spp. from mixed feeds and raw materials purchased in the Spanish market and used as feedstuffs. A total of 155 Penicillium spp. isolates belonging to 34 species were analyzed in order to know if they are able to produce OTA and/or CIT. From these isolates, 11 P. verrucosum which were characterized by RAPD analyses, produced OTA. Fourteen isolates were CIT producers, 10 isolates of P. verrucosum and 4 of P. citrinum. Although the occurrence and abundance of OTA and CIT Penicillium producing species have been low in our study, our results confirm the potential risk of OTA and CIT production in feeds if stored improperly. Our results also confirm the occurrence of P. verrucosum in South European countries and that it is the only OTA producing Penicillium species in these substrates.