Emulsifying and Foaming Properties of Protein Concentrates Prepared from Cowpea and Bambara Bean Using Different Drying Methods

Effect of cabinet-drying, vacuum-drying, and freeze-drying methods on the surface hydrophobicity, secondary structure, emulsifying, and foaming properties of protein concentrates prepared from different cultivars of cowpea and Bambara bean was investigated. The vacuum-drying method reduced hydrophobicity, while freeze-dried concentrates presented high hydrophobicity. The concentrates prepared by freeze drying presented more β-sheet (40–43%) and less β-turn (19–24%) structures. Bambara bean protein concentrates prepared by freeze-drying presented higher emulsifying activity (56–59%) compared to those by vacuum-drying and cabinet-drying, while emulsifying activity varied significantly among cultivars of cowpea (46–61%). Protein concentrates prepared by cabinet-drying showed the highest foaming ability.     

Using yeast RNA as a probe for generation of hydroxyl radicals by earth materials

Inhalation of certain types of particulate matter can lead to lung disease. The reactivity of these particles and, in part, the pathologic responses that result are dictated by their physicochemical properties. The ability of particles to induce the generation of reactive oxygen species (ROS), especially hydroxyl radicals in vivo, is one property that has been correlated to the development of lung disease. Several minerals, such as quartz and asbestos, are known to generate hydroxyl radicals and cause lung disease, but many other minerals have never been tested. Here, we describe a technique employing yeast RNA as a probe to screen for mineral-generated hydroxyl radicals. The stability of RNA in the presence of hydrogen peroxide, ferrous iron, hydroxyl radicals, and several common minerals (quartz, albite, forsterite, fayalite, hematite, magnetite, coal, and pyrite) was examined. 3'-(p-Aminophenyl) fluorescein (APF) was used to verify mineral generation of ROS. RNA is stable in the presence of hydrogen peroxide, quartz, and albite; while it degrades in the presence of ferrous iron, hydroxyl radicals, and the other minerals. Coal and pyrite are the most reactive both in RNA degradation and hydroxyl radical generation. This noncellular technique provides a straightforward way to compare many different particles simultaneously. Those particles showing reactivity toward RNA using this method are high-priority candidates for further in vitro and possibly in vivo tests.     

Milk fat composition modifies the texture and appearance of Cantal-type cheeses but not their flavor

Although the effects of cow diet on cheese sensory properties have been well documented, the putative interactions between the biochemical and microbial milk components and their respective roles in the development of the sensory properties of cheeses have yet to be explored in depth. The aim of this study was to evaluate the specific contribution of milk fat composition to the formation of cheese sensory properties. Two creams with different fat compositions were obtained from cows fed either pasture or maize silage. Cheeses were manufactured from the same skim milk (identical chemical and microbial composition) with either the pasture- or maize silage-origin pasteurized cream added. The gross composition and microbial composition of milks did not vary with cream origin. In milks and cheeses, the fatty acid (FA) profiles were modified by the origin of the cream. The concentrations of C18:0 and unsaturated FA such as cis-9 C18:1, trans-11 C18:1, C18:3n-3, total conjugated linoleic acids, and mono- and polyunsaturated FA were higher in milks and cheeses with the pasture-origin cream than in those with the maize-origin cream. In contrast, the maize milks and cheeses had higher concentrations of short- and medium-chain saturated FA, C16:0, and C18:2n-6. The level of lipolysis was 11% in the cheese rind and only 0.30% in the cheese core. The rind of pasture cheeses had a higher concentration of free C18:0 and C18:3n-3 and a lower concentration of free C14:0 and free C16:0 than the rind of maize cheeses. The levels of major microbial groups were similar in pasture and maize cheeses at different stages of ripening. The pasture cheeses had a more elastic and creamier texture, a yellower color, and a thinner rind than the maize cheeses, but the odor and aroma of cheeses were not affected by the origin of the cream, despite a few modifications in the balance of volatile compounds from FA catabolism. Based on these results, we conclude that milk fat composition modulated by cow diet had a direct role in the texture of the cheese but no effect on flavor. The high degree of lipolysis in cheese rind, along with the higher concentration of long-chain unsaturated free FA in pasture cheeses may be responsible for antimicrobial activity, which could explain differences in the appearance of cheese rind.     

Occurrence, sources, and fate of benzothiazoles in municipal wastewater treatment plants

A set of six benzothiazoles was determined in effluents of three municipal wastewater treatment plants. Total concentrations of benzothiazoles ranged from 1.9 to 6.7 microg/ L, with benzothiazole-2-sulfonate (BTSA) being most prominent (35 - 70%), followed by benzothiazole, 2-hydroxybenzothiazole, and 2-methylthi benzothiazole (MTBT). The removal of benzothiazoles in tertiary municipal wastewater treatment was investigated in more detail in one of the plants during two sampling periods of several weeks. Total benzothiazole concentration decreased by 5-28% only. This very limited removal was primarily due to BTSA and MTBT that were either hardly removed or even increased in concentration. In street runoff benzothiazoles exceeded the wastewater concentrations by 1 order of magnitude, showing that surface runoff can be a significant source of benzothiazole emission. In household wastewater total concentrations were in the range of 50-80% of that found in municipal wastewater. These investigations outline that benzothiazoles, a class of polar and biologically active industrial chemicals, are regularly released with treated municipal wastewater and exhibit a considerable lifetime in surface waters.     

Discovery and structural elucidation of the illegal azo dye Basic Red 46 in sumac spice

An unknown red dye was discovered in a sumac spice sample during routine analysis for Sudan dyes. LC-DAD and LC-MS/MS did not reveal the identity of the red substance. Nevertheless, using LC-high-resolution MS and isotope ratio comparisons the structure was identified as Basic Red 46. The identity of the dye was further confirmed by comparison with a commercial hair-staining product and two textile dye formulations containing Basic Red 46. Analogous to the Sudan dyes, Basic Red 46 is an azo dye. However, some of the sample clean-up methodology utilised for the analysis of Sudan dyes in food prevents its successful detection. In contrast to the Sudan dyes, Basic Red 46 is a cation. Its cationic properties make it bind strongly to gel permeation columns and silica solid-phase extraction cartridges and prevent elution with standard eluents. This is the first report of Basic Red 46 in food. The structure elucidation of this compound as well as the disadvantages of analytical methods focusing on a narrow group of targeted analytes are discussed.     

Chromium remediation or release? Effect of iron(II) sulfate addition on chromium(VI) leaching from columns of chromite ore processing residue

Chromite ore processing residue (COPR), derived from the so-called high lime processing of chromite ore, contains high levels of Cr(III) and Cr(VI) and has a pH between 11 and 12. Ferrous sulfate, which is used for remediation of Cr(VI) contamination in wastewater and soils via reduction to Cr(III) and subsequent precipitation of iron(III)/chromium(III) hydroxide, has also been proposed for remediation of Cr(VI) in COPR. Instead, however, addition of FeSO4 to the infiltrating solution in column experiments with COPR greatly increased leaching of Cr(VI). Leached Cr(VI) increased from 3.8 to 12.3 mmol kg(-1) COPR in 25 pore volumes with 20 mM FeSO4, reaching solution concentrations as high as 1.6 mM. Fe(II) was ineffective in reducing Cr(VI) to Cr(III) because it precipitated when it entered the column due to the high pH of COPR, while Cr(VI) in solution was transported away with the infiltrating solution. The large increase in leaching of Cr(VI) upon infiltration of sulfate, either as FeSO4 or Na2SO4, was caused by anion exchange of sulfate for chromate in the layered double hydroxide mineral hydrocalumite, a process for which scanning electron microscopy with energy-dispersive X-ray microanalysis provided direct evidence.     

Yoghurt fermented by Lactobacillus delbrueckii subsp. bulgaricus H+ -ATPase-defective mutants exhibits enhanced viability of Bifidobacterium breve during storage

Persistent acid production by Lactobacillus delbrueckii subsp. bulgaricus during refrigerated storage is a major cause of reduced viability of probiotic strains such as Bifidobacterium breve in yoghurt. It was established that H+ -ATPase-defective mutants of lactic acid bacteria have reduced growth and metabolism in low pH environments. Therefore, the aim of this study was to evaluate inhibition of post-acidification and maintenance of B. breve viability in yoghurt fermented by L. delbrueckii subsp. bulgaricus mutants with reduced membrane-bound H+ -ATPase activity during refrigerated storage. Spontaneous neomycin mutants of L. delbrueckii subsp. bulgaricus that had a significantly (P < or = 0.05) reduced H+ -ATPase activity were successfully isolated. Yoghurt fermented using L. delbrueckii subsp. bulgaricus SBT0164 No. 55-1 (mutant) starter culture had markedly reduced post-acidification and maintained viability (> or = 10(8) CFU/ml) of both Bifidobacteruim breve JCM 1192(T) and Bifidobacteruim breve JCM 7017 during storage at 10 degrees C for 21 days. These results clearly showed that yoghurt fermented by mutants of L. delbrueckii subsp. bulgaricus with reduced membrane-bound H+ -ATPase activity has reduced post-acidification that prolongs viability of B. breve in yoghurt during refrigerated storage.     

Prevalence of Salmonella spp. and Listeria monocytogenes at small-scale spanish factories producing traditional fermented sausages

The manufacturing of fermented sausages is subject to natural contamination processes that can potentially carry foodborne pathogens along the process chain and result in contamination of the final product. The aim of this study was to evaluate the occurrence of Salmonella spp. and Listeria monocytogenes at different sampling points during the manufacturing process of fuet, a type of traditional fermented sausage, at 10 small-scale Spanish factories. The presence of both pathogens was studied in the raw materials (19 casings and 19 meat batters), the final products (19 fermented sausages), and the factory equipment (12 mincing, 12 mixing, and 19 stuffing machines, 19 cutting tables, 11 knives, and 12 cold rooms) by using classical microbiological techniques and real-time PCR. Salmonella was not detected in the equipment analyzed or in the final products, but it was detected in the raw materials (23.7% of samples). L. monocytogenes showed higher incidence than Salmonella and was detected in the equipment (11.8% of samples), the raw materials (28.9%), and the final products (15.8%), confirming its ubiquity throughout the manufacturing process of fermented sausages. Five factories were further investigated to study the changes in the distribution of pathogens in the fuet production process over a period of either 2 or 3 years. There was considerable variation in the incidence of both pathogens at different sampling periods, and there was no relation between seasonal variations or geographic location of the factories.     

Inactivation of Enterobacter sakazakii in infant milk formula by gamma irradiation: determination of D10-value

ABSTRACT:  Enterobacter sakazakii is an emerging foodborne pathogen that has caused several cases of meningitis and necrotizing entercolitis in infants and has been associated with infant formulas. Five strains of E. sakazakii were inoculated individually into brain heart infusion broth and rehydrated or dehydrated infant milk formula and exposed to ionizing radiation. E. sakazakii strains in brain heart infusion broth and rehydrated infant milk formula (RIMF) were exposed to irradiation dose of up to 1 kGy while strains in dehydrated infant milk formula (DIMF) were exposed to irradiation dose of up to 9 kGy. The D₁₀-values were determined by using a linear regression model. Average calculated D₁₀-values ranged from 0.21 to 0.29 kGy, 0.24 to 0.37 kGy, and 1.06 to 1.71 kGy in brain heart infusion broth, RIMF, and DIMF, respectively. The results obtained from this study will be useful for powdered infant milk formula industries to reduce the risk associated with E. sakazakii .