Microbiological quality and safety of fresh cultivated and wild mushrooms commercialized in Spain

402 samples of 22 species of cultivated and wild fresh mushrooms sold in retail markets and supermarkets in Zaragoza (Spain) were studied to quantify their microbial load (mesophilic aerobic microorganisms, Pseudomonas genus, Enterobacteriaceae, lactic acid bacteria, total and thermotolerant coliform bacteria, Escherichia coli, yeasts and moulds) and to investigate the presence of E. coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Yersinia enterocolitica. The total microbial counts ranged from 4.4 to 9.4 log cfu/g, the genus Pseudomonas being the most prevalent with counts from 3.7 to 9.3 log cfu/g and Auricularia auricula-judae the species with the highest microbial load (9.4 log cfu/g). No significant differences (p > 0.05) were detected between mean counts of wild and cultivated species in all the microbial groups studied. The microbiological safety level of the cultivated mushrooms was excellent since no pathogens were isolated, and the microbial counts of indicator microorganisms were low, being detected in only half of the species. Salmonella spp, E. coli O157:H7 and S. aureus were not isolated from any sample, Y. enterocolitica was detected in only four samples of wild mushrooms whereas twenty-six (6.5%) were positive for L. monocytogenes, their occurrence being relatively high in Calocybe gambosa (40%), Hygrophorus limacinus (40%) and Tuber indicum (100%). These results suggest that a strategy to reduce bacterial populations, and to improve the microbiological safety of some species of fresh mushrooms, should be investigated.     

The functional, rheological and sensory characteristics of ice creams with various fat replacers

The effects of fat replacers (Simplesse® D-100, N-Lite D, and inulin) on the melting characteristics, overruns, hardness, rheological parameters and sensory attributes of reduced (RF, 60.0 g/kg), low (LF, 40.0 g/kg), and nonfat (NF, 1.0 g/kg) ice creams were investigated. The magnitudes of the melting rates were in the order RF>LF>NF for samples that contained Simplesse® D-100 or inulin, but the reverse order was found for samples with N-Lite D. The nonfat ice creams had lowest overrun values of around 10%. Inulin-containing ice creams possessed higher overrun values than others ( P  > 0.05). The use of fat replacer decreased the hardness of ice creams. All ice cream samples showed pseudoplastic (shear-thinning) behavior. The addition of N-Lite D and inulin decreased the flow behaviour index of ice cream samples. The reduced and low fat ice cream samples were rated as similar to the control by a sensory panel. On the other hand, no correlations ( P  > 0.05) were observed between rheological parameters and sensory texture and mouthfeel.     

Speciated ambient carbonyls in Rio de Janeiro, Brazil

Carbonyls in urban air continue to receive scientific and regulatory attention as toxic air contaminants and for their important role in photochemical smog. However, few data are available for speciated carbonyls in urban air. Ambient concentrations of up to 61 carbonyls have been measured in Rio de Janeiro, Brazil. The most abundant carbonyls were formaldehyde and acetaldehyde (study-averaged concentrations of 10.8 +/- 4.1 and 10.4 +/- 4.6 microg m(-3), respectively, in samples of 3-h duration collected from May to November 2000 at a downtown location during the morning vehicle commute) followed by acetone, 2-butanone, and benzaldehyde. Ambient concentrations of other carbonyls (except acetophenone) correlated well with those of acetaldehyde and of formaldehyde. This study examines the ambient acetaldehyde/ambient formaldehyde concentration ratio in Brazilian cities since the mid-1980s in the context of changes in Brazil's reliance on ethanol as a vehicle fuel. This ratio has begun to decrease in recent years due to fleet turnover and is likely to decrease further as older cars fueled with ethanol are replaced by lower-emitting models that run on a gasoline-ethanol blend. The carbonyls measured are ranked with respect to ozone formation potential (using MIR coefficients) and reaction with OH (using carbonyl-OH reaction rate constants). Ozone formation is dominated by formaldehyde (43% of total) followed by acetaldehyde (32%) and methylglyoxal (8%); other carbonyls each contributed < or = 4% of total. For reaction with OH, acetaldehyde ranks first closely followed by formaldehyde.     

Fat destabilization and melt-down of ice creams with increased protein content

Effects of individual protein sources or blends on microstructure and melt-down rates of ice cream were investigated. Ice creams were formulated with non-fat dry milk (NFDM), milk protein concentrate, whey protein isolate (WPI), or procream to total protein concentrations of 4–10%. Ice creams were also made with protein blends containing 4% protein from NFDM with additional WPI or procream to total protein concentrations of 6–10%. Mean ice crystal and air cell sizes and overrun were not significantly impacted by protein source, blend, or concentration. Partially-coalesced fat decreased with increasing protein content, except in ice creams made with only NFDM. Melt rate tended to increase with protein content, with the exception of ice creams made with procream, which gave rapid melt rates at all protein concentrations. Protein type, blend and concentration were hypothesized to affect the properties of the emulsion interface, leading to differences in partial coalescence and melt-down rates.     

Determination of certain quality characteristics,thermal and sensory properties of ice creams produced with dried Besni grape (Vitis vinifera L.)

In this study, the effect of adding dried Besni grape (BG) at different concentrations on the physico‐chemical characteristics, colour values, total phenolic and flavonoid contents, glass transition (), melting (), freezing (T_f) and melting (T_m) point temperatures, and sensory properties of ice creams was investigated. Generally, the addition of BG caused a statistically significant (P < 0.01) increase in total solids, ash, fat, viscosity, first dripping times, complete melting times and a* colour values, while it decreased protein, pH, overrun, L*, b*, , , T_f and T_m values. The colour scores of ice cream samples showed a statistically significant increase (P < 0.05) with the increment of BG concentration, while the effects of BG addition on texture, resistance to melting, flavour, gumming structure and overall acceptability scores were not statistically significant.     

Production of functional probiotic, prebiotic, and synbiotic ice creams

In this work, 3 types of ice cream were produced: a probiotic ice cream produced by adding potentially probiotic microorganisms such as Lactobacillus casei and Lactobacillus rhamnosus; a prebiotic ice cream produced by adding inulin, a prebiotic substrate; and a synbiotic ice cream produced by adding probiotic microorganisms and inulin in combination. In addition to microbial counts, pH, acidity, and physical and functional properties of the ice creams were evaluated. The experimental ice creams preserved the probiotic bacteria and had counts of viable lactic acid bacteria after frozen storage that met the minimum required to achieve probiotic effects. Moreover, most of the ice creams showed good nutritional and sensory properties, with the best results obtained with Lb. casei and 2.5% inulin.     

Characterization of Staphylococcus aureus isolates recovered from bovine mastitis in Rio de Janeiro, Brazil

Phenotypic characteristics, antimicrobial susceptibility, and genetic relationships were analyzed in 107 Staphylococcus aureus isolates recovered from cows with subclinical mastitis in Southeastern Brazil. Thirteen different biochemical patterns were detected among isolates. A predominant pattern represented by about 54% of the isolates was distributed among several herds. Isolates of distinct phenotypic profiles were also detected within a herd. Susceptibility to ampicillin, cefotaxime, cephalotin, chloramphenicol, erythromycin, gentamycin, kanamycin, nitrofurantoin, norfloxacin, ofloxacin, oxacillin, penicillin, rifampin, sulfamethoxazole-trimethoprim, tetracycline, trimethoprim, and vancomycin, determined by the disk diffusion method, was observed in 44.9% of isolates. On the other hand, 55.1, 7.4, and 2.8% of the strains were resistant to ampicillin/penicillin, tetracycline, and erythromycin, respectively. Genetic diversity was analyzed by pulsed-field gel electrophoresis using SmaI as the restriction enzyme. All isolates could be typed by pulsed-field gel electrophoresis, which identified 16 types and 24 subtypes. Type A and its subtypes comprised 54.2% of all isolates and were recovered from 6 of the 9 herds analyzed. Other types and subtypes were also found in multiple herds. Although multiple types and subtypes were found within a specific herd, a predominant type was frequently observed.     

冰淇淋质量缺陷与质量管理

本文介绍了优良品质的冰淇淋必备的条件、冰淇淋品质的缺陷及分析产生的原因，为使品质优良必须经常检查原材料以及对制造过程进行严格的控制。     

The effects of the combined use of stabilizers containing locust bean gum and of the storage time on Kahramanmaraş-type ice creams

This study was aimed primarily at determining the suitability of locust bean gum and various stabilizers in the production of Kahramanmaraş-type ice creams, the physical, chemical and sensory properties of the ice creams produced, and the stabilizer combination that could produce the best quality ice cream. With a total amount of stabilizer of 1.0%, ice creams of four different combinations containing locust bean gum, carboxymethyl cellulose, guar gum and sodium alginate were produced and their properties during a 6-month storage period compared with the control sample produced using only salep extract ( Orchis orchida ).
  The ice cream produced using only the salep extract had significantly higher ( P  < 0.05) levels of titratable acidity, lower pH and viscosity values, and were harder and less resistant to melting compared to those produced with the stabilizer combinations. The stabilizer mixtures containing locust bean gum yielded better results than those with the salep extract. An analysis of the effect of storage time on the properties of the ice creams indicated that, of the physical properties examined, only the decrease in the penetrometer values was significant ( P  < 0.05). Apart from the difference observed in the third month during the storage of the ice creams produced with the salep extract, the differences during the storage time were not found to be significant ( P  > 0.05).     

Ochratoxin A in wines from 2002 to 2008 harvest marketed in Rio de Janeiro,Brazil

The occurrence of ochratoxin A (OTA) in wine from 2002 to 2008 harvest, traded in Rio de Janeiro State, was evaluated by analysing 43 national and 37 imported wines from Argentina (32) and Chile (5), adding up to 80 samples in total. OTA determination was performed using immunoaffinity columns and high-performance liquid chromatography. In 80 wine samples analysed, 25 (31.3%) were positive, presenting levels greater than 0.020?ng OTA mL^?1. It was not detected in imported wines. Within national wines, 58.1% of the samples were contaminated, with levels ranging from 0.020 to 0.050?ng?mL^?1. The toxin was detected in 18 (69.2%) of 26 samples analysed of red table wine. Wines from 2008 harvest presented 84.6% of samples contaminated in 13 samples analysed. Despite the levels found in this study, they are below Brazilian tolerance limits. Nevertheless, the presence of OTA as found contributes to the human exposure to this toxin.     

Enrichment of ice cream with dietary fibre: Effects on rheological properties,ice crystallisation and glass transition phenomena

In the present study, the effects of four dietary fibre sources (oat, wheat, apple and inulin) on the rheological and thermal properties of model sucrose–polysaccharides solutions and ice cream mixes were investigated. The content of fibre in insoluble compounds increased significantly the viscosity and the shear thinning behaviour of the model solutions and ice creams, due to the increase of total solids and the formation of networks comprised of hydrated cellulose and hemicellulose. The increase of soluble material did not alter significantly the rheology of the samples but limited the freezing point depression and elevated the glass transition temperatures, indicating a potential cryoprotective action. The use of oat and wheat fibre favoured viscosity development due to water-binding, whereas inulin caused a remarkable increase of glass transition temperature (T_g) in model solutions and ice cream mixes, indicating the reduction of water molecule mobility from the bulk aqueous phase to the ice crystals’ surface. Apple fibre addition greatly increased viscosity and elevated the T_g values, particularly in the presence of proteins. Thus, our results suggest the potential use of dietary fibres as crystallisation and recrystallisation phenomena controllers in frozen dairy products.     

Impact of disperse microstructure on rheology and quality aspects of ice cream

Oscillatory thermo-rheometry (OTR) was used to correlate rheological properties with the microstructure and quality characteristics of ice cream. In a rotational rheometer (plate-plate geometry) the rheological behavior of ice cream was studied, performing oscillatory measurements at low deformation amplitudes for three different temperature ranges corresponding to important consumer properties of ice cream.The ice crystal microstructure determined the rigidity and “scoopability” of ice cream at low temperatures (−20°C to −10°C). The higher the overrun and the smaller the connectivity of ice crystals, the smaller were the measured storage and loss moduli G′ and G″.The slope of the variations in G′ and G″ with temperature in the range between −10°C and 0°C were correlated with the sensory impression of coldness. Decreasing overrun levels led to steeper slopes and correspondingly to a more pronounced impression of coldness.The microstructures of air and fat phases had also a significant impact on the rheology and the sensorial “creaminess” of ice cream especially in the molten state (0-10°C). With increasing overrun levels, ice cream showed increasing storage and loss moduli at temperatures higher than 0°C. Smaller air bubble sizes and increased fat globule aggregation in low temperature extruded (LTE) ice cream led to higher values of G″ in comparison to conventionally hardened (Freezer) ice cream.Sensorial studies demonstrated a close correlation between loss moduli G″ measured in the OTR-test and the ice cream quality parameters scoopability and creaminess. The improved scoopability and increased creaminess of LTE ice cream in comparison to Freezer ice cream was measured quantitatively by a decrease of G″ at a temperature of −15°C and a increase of G″ for ice cream in the molten state.     

Short communication: profile of virulence factors of Staphylococcus aureus isolated from subclinical bovine mastitis in the state of Rio de Janeiro, Brazil

Staphylococcus aureus produces exoproteins that contribute to its ability to colonize the mammary gland such as hemolysins, coagulase, slime, and protein A. This study characterized phenotypically and genotypically these virulence factors in 50 Staph. aureus isolates. These isolates were obtained from milk samples from subclinical mastitis cases identified in 15 dairy cattle farms located in the state of Rio de Janeiro, Brazil. All of the confirmed Staph. aureus samples were PCR positive for the coa gene, which displayed 3 different size polymorphisms. The amplification of the spaA X region yielded a single amplicon for each isolate with the prevalent amplicon sized 315 bp. The Staph. aureus isolates were 24 and 16% positive for the hla and hlb genes, respectively, and 22 and 20% positive for the icaA and icaD genes, respectively. Amplification of the agr gene RNAIII was positive in 74% of the strains. Twenty-seven different profiles were identified among the samples, indicating a great diversity of Staph. aureus involved in the etiology of mastitis cases in the analyzed region. These findings are valuable to the comprehension of the distribution of the profiles of Staph. aureus strains isolated from subclinical mastitis cases in the state of Rio de Janeiro.     

Occurrence of ochratoxin A in wine and grape juice marketed in Rio de Janeiro, Brazil.

Ochratoxin A (OA) is receiving attention world-wide because of the hazard it poses to human health. The aim was to test the distribution of OA in grape juice, pulps of frozen grapes, and national and imported table wine obtained from markets in Rio de Janeiro, Brazil. Analytical methodology using immunoaffinity column for OA extraction and clean-up with a final separation on a reversed-phase (C(18)) column and fluorescence detection in high-performance liquid chromatography showed a detection limit of 21 ng l(-1). The mean recovery was 91% for red wines and 82% for white wines; while the mean recoveries for juices and pulps of frozen grapes were 91.6 and 88%, respectively. Of 64 samples of grape juice and frozen pulps, 25% were positive for OA, being the mean content of 37 ng l(-1) with a maximum concentration of 100 ng l(-1). In wines, the mean concentration detected in 80 samples analysed was 34.4 ng l(-1) with 28.75% of positive samples. Red wines showed the highest percentages and levels of contaminated samples: 38% and 37 ng l(-1), respectively. The white wine contained levels above 26 ng l(-1) in 17.75% of the analysed samples. The levels of contamination detected in red wine sold in Río de Janeiro were not enough to surpass the virtually safe dose established as 5 n g kg(-1) body weight of daily intake.     

改性大豆分离蛋白-磷脂复合物对冰淇淋品质的影响

针对大豆分离蛋白(SPI)取代部分乳粉生产冰淇淋,产品膨胀率低、易融化、口感较硬和有豆腥味等问题,本实验采用超高压改性大豆分离蛋白(USPI)、大豆分离蛋白-磷脂复合物(SPI-PLW)和超高压均质改性大豆分离蛋白-磷脂复合物(USPI-PLW)分别替代乳粉生产冰淇淋,研究了不同改性条件的大豆蛋白对冰淇淋浆料的静态流变学、膨胀率、融化率、硬度和微观结构的影响。通过对比研究得出,以USPI-PLW为原料制作成的冰淇淋的各项标准都优于其它类型的大豆分离蛋白冰淇淋。USPI-PLW冰淇淋融化率为33.17%,膨胀率可达86.86%,较传统低脂冰淇淋融化率降低26.86%,膨胀率提高了94.84%,且储藏硬化后无较大冰晶,相对于传统冰淇淋口感更绵软。     

大豆粉取代奶粉对冰淇淋品质的影响

在冰淇淋配方中以0~80%的大豆粉取代脱脂奶粉,对冰淇淋浆料进行了流变学、稳定性、粒度检测及对冰淇淋的膨胀率与抗融性进行测定,揭示了大豆粉的取代量对冰淇淋品质的影响。研究结果表明,随着大豆粉添加量的增加,冰淇淋浆料粘度显著增加,稳定性增强,而粒径差异不显著,针对于最终冰淇淋产品而言,其膨胀率呈现先上升(20%~40%)后下降(60%~80%)的趋势,但其抗融性逐渐增强,与此同时,豆味的表现也会加强,取代量大于60%时,豆香味则占主导。      

Contribution of thermal,rheological and physical measurements to the determination of sensorially perceived quality of ice cream containing bulk sweeteners

The role of rheological measurements, thermal analysis and physical properties such as overrun, instrumental hardness and melting behavior on sensorial profile mapping of vanilla ice cream was evaluated. Samples with different functional characteristics were prepared partially substituting sucrose by bulk sweeteners. Creaminess apart from thermal properties (glass transition temperature-T_g, ice crystal uniformity-ΔΤ_mcurve and unfrozen water content-UFW) was poorly related with rheological and physical properties. On the contrary, coarseness, wateriness, greasiness and gumminess perception were found to be well correlated with rheological and thermal properties, overrun, air cells mean size and melting rate. Flavor and taste characteristics were interrelated particularly with melting and thermal characteristics, overrun and air cells mean size. Multivariate exploratory statistical methods revealed that the use of T_g, ΔΤ_mcurve, UFW, instrumental hardness, and melting rate can be used for the effective discrimination of ice creams differing in their sweetener composition suggesting their importance in the design of novel ice cream formulations.     

Assessment of Microbiological and Bio-chemical Quality of Fish in a Supply Chain in Negombo,Sri Lanka

This study aimed to investigate quality of fish landed in Negombo area and distributed in suburban areas in Western province of Sri Lanka. Hundred samples of large fish (Katsuwonus pelamis and Euthynnus affinis) and 60 samples of small fish (Amblygaster sirm, Pterocaesio chrysozona, Stolephorus commersoni, and Sardinella albella) were sampled from different stages of a supply chain at five and six sampling visits, respectively. All fish samples (N=160) were analysed for aerobic plate counts (APC) at 37^oC, Coliforms, feacal coliforms, Escherichia coli, Salmonella spp., Listeria monocytogenes, total volatile base nitrogen (TVB-N) while 130 were analysed for histamine. Water from fishery harbor basin, fishery harbour, ice manufcaturing plants and ice used in multiday boats were also analysed for microbiological parameters. Large and small fish contained APC in the range of 2.0 x10² - 2.0 x 10⁶ and 8.0×10³ - 2.0×10⁸ cfu/g, respectively. Faecal coliform counts ranged between not detected (ND) and 90 MPN/g in large fish and between ND and >1100 MPN/g in small fish. 5% of large fish were contaminated with E.coli and ranged from ND to 15 MPN/g. E.coli was present in 70% of small fish samples and ranged from ND to >1100 MPN/g. Of the 160 fish samples, tested Salmonella spp were detected in nine occassions. Of the 160 fish samples, L. monocytogenes was found in eight Katsuwonus pelamis and one Sardinella albella fish. TVB-N of large fish were found at range of 1-67 mgN/100 g and 79% samples contained unaccptable levels. Small fish contained about 25.10-104.30 mgN/100 g while 78% samples exceeded acceptable levels. Histamine level of large and small fish, 26% and 83% of samples exceeded the maximum acceptable levels, respectively. Harbour basin water was heavily contaminated with Salmonella spp. (50%), Faecal streptococci (100%), Faecal coliforms and E.coli (100%). Ice samples (20%) from one ice plant were found contaminated with Salmonella spp.