Raakamaidon solupitoisuus Suomessa vuonna 1995

Osmo Myllykangas

Raakamaidon bakteriologinen laatu Suomessa vuonna 1995

Osmo Myllykangas

New infectious mammary tumor virus superantigen with V beta-specificity identical to staphylococcal enterotoxin B (SEB).

Only few infectious mouse mammary tumor viruses (MMTV) have been characterized which induce a potent superantigen response in vivo. Here we describe the characterization of an MMTV which was isolated from milk of the highly mammary tumor-prone SHN mouse strain. Exposure of newborn mice to milk-borne MMTV (SHN) results in a very slow deletion of V beta 7, 8.1, 8.2 and 8.3 expressing peripheral T cells. Subcutaneous injection of adult mice with this virus induces a rapid and strong stimulation of all four affected V beta-subsets in vivo. Besides the strong T cell effect we observed an early proliferation and activation of the local B cell pool leading to the initial secretion of IgM followed by preferential secretion of IgG2a by day 6. Sequence comparison of the polymorphic C terminus with known open reading frames revealed high homology to the endogenous provirus Mtv-RCS. This is the first report of a virus having a complete overlap in V beta-specificity with a bacterial superantigen stimulating as many as 35% of the whole CD4+ T cell repertoire including V beta 8.2.

Qualidade de queijo minas frescal preparado com leite com diferentes quantidades de células somáticas

The objective of this work was to evaluate the effects of using bulk milk with different somatic cell counts (SCC) on the quality of minas frescal cheese. A randomized complete block design was used, with 3x5 factorial treatments, with three SCC levels (low, 125,000 cells mL-1; intermediate, 437,000 cells mL-1; and high, 1,053,000 cells mL-1) and five storage durations. Cheese was vacuum-packed in plastic bags and analyzed after 2, 9, 16, 23 and 30 days of storage at 4ºC. Somatic cell counts did not affect dry matter, fat, ash content, pH, free fatty acid concentrations and sensory parameters of minas frescal cheese. However, SCC in milk increased losses of protein in whey and decreased the cheese protein content. These changes did not affect the moisture-adjusted cheese yield and proteolysis during 30 days of storage. An interaction effect between SCC and time of storage was observed for firmness and sensory grades of cheeses. Results indicated that raw milk used to produce minas frescal cheese should not contain high SCC, in order to avoid lower acceptance of the product after 30 days of storage.

NaOCl effect on biofilm produced by Staphylococcus aureus isolated from the milking environment and mastitis infected cows

Biofilms constitute a physical barrier, protecting the encased bacteria from detergents and sanitizers. The objective of this work was to analyze the effectiveness of sodium hypochlorite (NaOCl) against strains of Staphylococcus aureus isolated from raw milk of cows with subclinical mastitis and Staphylococcus aureus isolated from the milking environment (blowers and milk conducting tubes). The results revealed that, in the presence of NaOCl (150ppm), the number of adhered cells of the twelve S. aureus strains was significantly reduced. When the same strains were evaluated in biofilm condition, different results were obtained. It was found that, after a contact period of five minutes with NaOCl (150ppm), four strains (two strains from milk , one from the blowers and one from a conductive rubber) were still able to grow. Although with the increasing contact time between the bacteria and the NaOCl (150ppm), no growth was detected for any of the strains. Concerning the efficiency of NaOCl on total biofilm biomass formation by each S. aureus strain, a decrease was observed when these strains were in contact with 150 ppm NaOCl for a total period of 10 minutes. This study highlights the importance of a correct sanitation protocol of all the milk processing units which can indeed significantly reduce the presence of microorganisms, leading to a decrease of cow´s mastitis and milk contamination.

Room temperature aging to guarantee microbiological safety of Brazilian artisan Canastra cheese

Canastra cheese is one of the oldest and most traditional cheeses made from raw milk in Brazil. However, this type of practice may have severe consequences for human health. According to the current legislation, any cheese made from raw milk must be aged for at least 60 days. Traditionally, Canastra cheese is consumed after different ripening periods, but consumers usually prefer those that are aged less than eight days. This study aimed to evaluate the effects of physicochemical and microbiological parameters, with emphasis on the pathogenic microbiota regulated by law, on cheese aged at room temperature and under refrigeration. Cheese samples were collected from eight different cheese producers located in the Serra da Canastra region twice a year (rainy and dry seasons) and analyzed with 8, 15, 22, 29, 36, and 64 days of ripening. Room temperature aging effectively reduced pathogens, reaching the total count established by law in 22 days, regardless of the season. However, ripening under refrigeration, it was ineffective in reducing the Staphylococcus aureus counts to the legislation limits, even after 64 days. Therefore, Canastra cheese should be ripened for at least 22 days at room temperature in order to fulfill the safety regulatory limits.

Antimicrobial properties of lactic acid bacteria isolated from uruguayan artisan cheese

Uruguayan artisan cheese is elaborated with raw milk and non-commercial starters. The associated native microbiota may include lactic acid bacteria and also potentially pathogenic bacteria. Lactic acid bacteria were isolated from artisan cheese, raw milk, and non-commercial starter cultures, and their potential bacteriocin production was assessed. A culture collection of 509 isolates was obtained, and five isolates were bacteriocin-producers and were identified as Enterococcus durans,Lactobacillus casei, and Lactococcus lactis. No evidence of potential virulence factors were found in E. durans strains. These are promising results in terms of using these native strains for cheese manufacture and to obtain safe products.

Effect of management strategies on the performance of ruminant livestock production systems and the safety of plant and animal products in the city of Sikasso, Mali

The regional population growth in West Africa, and especially its urban centers, will bring about new and critical challenges for urban development policy, especially in terms of ensuring food security and providing employment for the growing population. (Peri-) urban livestock and vegetable production systems, which can contribute significantly to these endeavours, are limited by various constraints, amongst them limited access to expensive production factors and their (in)efficient use. To achieve sustainable production systems with low consumer health risks, that can meet the urban increased demand, this doctoral thesis determined nutrient use efficiencies in representative (peri-) urban livestock production systems in three West African cities, and investigated potential health risks for consumers ensuing from there. The field study, which was conducted during July 2007 to December 2009, undertook a comparative analysis of (peri-) urban livestock production strategies across 210 livestock keeping households (HH) in the three West African cities of Kano/Nigeria (84 HH), Bobo Dioulasso/Burkina Faso (63 HH) and Sikasso/Mali (63 HH). These livestock enterprises were belonging to the following three farm types: commercial gardening plus field crops and livestock (cGCL; 88 HH), commercial livestock plus subsistence field cropping (cLsC; 109 HH) and commercial gardening plus semi-commercial livestock (cGscL; 13 HH) which had been classified in a preceding study; they represented the diversity of (peri-) urban livestock production systems in West Africa. In the study on the efficiency of ruminant livestock production, lactating cowsand sheep herd units were differentiated based on whether feed supplements were offered to the animals at the homestead (Go: grazing only; Gsf: mainly grazing plus some supplement feeding). Inflows and outflows of nutrients were quantified in these herds during 18 months, and the effects of seasonal variations in nutrient availability on animals’ productivity and reproductive performance was determined in Sikasso. To assess the safety of animal products and vegetables, contamination sources of irrigated lettuce and milk with microbiological contaminants, and of tomato and cabbage with pesticide residues in (peri-) urban agriculture systems of Bobo Dioulasso and Sikasso were characterized at three occasions in 2009. Samples of irrigation water, organic fertilizer and ix lettuce were collected in 6 gardens, and samples of cabbage and tomato in 12 gardens; raw and curdled milk were sampled in 6 dairy herds. Information on health risks for consumers of such foodstuffs was obtained from 11 health centers in Sikasso. In (peri-) urban livestock production systems, sheep and goats dominated (P<0.001) in Kano compared to Bobo Dioulasso and Sikasso, while cattle and poultry were more frequent (P<0.001) in Bobo Dioulasso and Sikasso than in Kano. Across cities, ruminant feeding relied on grazing and homestead supplementation with fresh grasses, crop residues, cereal brans and cotton seed cake; cereal grains and brans were the major ingredients of poultry feeds. There was little association of gardens and livestock; likewise field cropping and livestock were rarely integrated. No relation existed between the education of the HH head and the adoption of improved management practices (P>0.05), but the proportion of HH heads with a long-term experience in (peri-) urban agriculture was higher in Kano and in Bobo Dioulasso than in Sikasso (P<0.001). Cattle and sheep fetched highest market prices in Kano; unit prices for goats and chicken were highest in Sikasso. Animal inflow, outflow and dairy herd growth rates were significantly higher (P<0.05) in the Gsf than in the Go cattle herds. Maize bran and cottonseed expeller were the main feeds offered to Gsf cows as dry-season supplement, while Gsf sheep received maize bran, fresh grasses and cowpea pods. The short periodic transhumance of Go dairy cows help them maintaining their live weight, whereas Gsf cows lost weight during the dry season despite supplement feeding at a rate of 1506 g dry matter per cow and day, resulting in low productivity and reproductive performance. The daily live weight gains of calves and lambs, respectively, were low and not significantly different between the Go and the Gsf system. However, the average live weight gains of lambs were significantly higher in the dry season (P<0.05) than in the rainy season because of the high pressure of gastrointestinal parasites and of Trypanosoma sp. In consequence, 47% of the sheep leaving the Go and Gsf herds died due to diseases during the study period. Thermo-tolerant coliforms and Escherichia coli contamination levels of irrigation water significantly exceeded WHO recommendations for the unrestricted irrigation of vegetables consumed raw. Microbial contamination levels of lettuce at the farm gate and the market place in Bobo Dioulasso and at the farm gate in Sikasso were higher than at the market place in Sikasso (P<0.05). Pesticide residues were detected in only one cabbage and one tomato sample and were below the maximum residue limit for consumption. Counts of thermo-tolerant coliforms and Escherichia coli were higher in curdled than in raw milk (P<0.05). From 2006 to x 2009, cases of diarrhea/vomiting and typhoid fever had increased by 11% and 48%, respectively, in Sikasso. For ensuring economically successful and ecologically viable (peri-) urban livestock husbandry and food safety of (peri-) urban foodstuffs of animal and plant origin, the dissemination and adoption of improved feeding practices, livestock healthcare and dung management are key. In addition, measures fostering the safety of animal products and vegetables including the appropriate use of wastewater in (peri-) urban agriculture, restriction to approve vegetable pesticides and the respect of their latency periods, and passing and enforcement of safety laws is required. Finally, the incorporation of environmentally sound (peri-) urban agriculture in urban planning by policy makers, public and private extension agencies and the urban farmers themselves is of utmost importance. To enable an efficient (peri-) urban livestock production in the future, research should concentrate on cost-effective feeding systems that allow meeting the animals’ requirement for production and reproduction. Thereby focus should be laid on the use of crop-residues and leguminous forages. The improvement of the milk production potential through crossbreeding of local cattle breeds with exotic breeds known for their high milk yield might be an accompanying option, but it needs careful supervision to prevent the loss of the local trypanotolerant purebreds.

Efectos sobre el sector lácteo en Colombia de la desgravación simultanea de aranceles a los productos del sector, negociada en el tratado de libre comercio con la Unión Europea

Con la firma del Tratado de Libre Comercio (TLC) entre los países que conforman la Unión Europea (UE) y Colombia, se abre un camino complejo y dinámico de flujos en comercio exterior que, sin duda, traerá beneficios y desventajas para la actividad productora de leche cruda en Colombia, a raíz de la forma como se hicieron las negociaciones del acuerdo. Partiendo de esta premisa, el presente trabajo de grado, hace un análisis cualitativo de los efectos previsibles que la implementación del TLC de la referencia tendrá sobre el sector lácteo en Colombia

Estudo da presença de Mycobacterium avium subespécie paratuberculosis numa exploração leiteira no Litoral Centro de Portugal Continental

A Paratuberculose, conhecida também como Doença de Johne, é uma afeção infecciosa que provoca uma enterite granulomatosa crónica causada pelo agente Mycobacterium avium subespécie paratuberculosis (Map). É uma doença de carácter contagioso, de distribuição mundial, atingindo os mamíferos, particularmente os pequenos e grandes ruminantes, equinos, suínos, búfalos, coelhos, etc. Tem um grande impacto económico, nomeadamente na redução da produção leiteira, na redução dos teores de proteína no leite, na susceptibilidade a outras doenças, no refugo de animais e no aumento dos custos na sanidade. Pensa-se que também terá impacto a nível de Saúde Pública uma vez que o Map pode estar associado á doença de Crohn em humanos em que o leite cru, leite em pó ou leite pasteurizado podem ser os veículos de transmissão, porém não existem estudos suficientes para sustentar este acontecimento. A técnica de diagnóstico “Gold Standard” é a cultura microbiológica de fezes, no entanto é um procedimento muito demorado podendo levar até 4 meses para se observarem as colónias bacterianas, uma vez que o seu crescimento é muito lento. Deste modo, existem outros testes, tais como o PCR e ELISA, com elevada especificidade para o agente que fornecem resultados mais rápidos e que permitem minimizar os falsos-positivos, apesar da sua reduzida sensibilidade (por volta dos 50%). Este estudo é baseado na observação das instalações da exploração e consequente comparação com parâmetros analisados e documentados em literatura. Para além disso, são utilizadas informações fornecidas pelo Software da exploração com o intuito de estudar a incidência da Paratuberculose, ao longo dos anos, de modo a comprovar se as medidas de maneio e de higiene adotadas pela exploração afetada contribuem ou não de alguma maneira para o controlo/erradicaçãoda doença de Johne.

Chemical, physical, and sensory properties of dairy products enriched with conjugated linoleic acid

Recent studies have illustrated the effects of cis-9, trans-11 conjugated linoleic acid (CLA) on human health. Ruminant-derived meat, milk and dairy products are the predominant sources of cis-9, trans-11 CLA in the human diet. This study evaluated the processing properties, texture, storage characteristics, and organoleptic properties of UHT milk, Caerphilly cheese, and butter produced from a milk enriched to a level of cis-9, trans-11 CLA that has been shown to have biological effects in humans. Forty-nine early-lactation Holstein-British Friesian cows were fed total mixed rations containing 0 (control) or 45 g/kg ( on dry matter basis) of a mixture (1:2 wt/wt) of fish oil and sunflower oil during two consecutive 7-d periods to produce a control and CLA-enhanced milk, respectively. Milk produced from cows fed the control and fish and sunflower oil diets contained 0.54 and 4.68 g of total CLA/100 g of fatty acids, respectively. Enrichment of CLA in raw milk from the fish and sunflower oil diet was also accompanied by substantial increases in trans C18:1 levels, lowered C18: 0, cis-C18:1, and total saturated fatty acid concentrations, and small increases in n-3 polyunsaturated fatty acid content. The CLA-enriched milk was used for the manufacture of UHT milk, butter, and cheese. Both the CLA-enhanced butter and cheese were less firm than control products. Although the sensory profiles of the CLA-enriched milk, butter, and cheese differed from those of the control products with respect to some attributes, the overall impression and flavor did not differ. In conclusion, it is feasible to produce CLA-enriched dairy products with acceptable storage and sensory characteristics.

Risco à saúde representado pelo consumo de leite cru comercializado clandestinamente

Foram submetidas às contagens de microrganismos mesófilos, Staphylococccus coagulase positiva, e às determinações do número mais provável (NMP) de coliformes totais e de coliformes fecais, 60 amostras de leite cru comercializado clandestinamente nos Municípios de Botucatu e de São Manuel, Estado de São Paulo, Brasil. Os resultados obtidos evidenciaram a ocorrência de 41 (68,3%) e 50 (83,3%) amostras com contagens de microrganismos mesófilos e de coliformes totais, respectivamente, acima dos limites máximos estabelecidos pelo Ministério da Saúde para o leite pasteurizado tipo C. Evidenciaram, ainda, a presença de 30 (50,0%) e 11 (18,3%) amostras contaminadas por cepas de Staphylococcus coagulase positiva e por coliformes fecais, respectivamente. Apenas 5 (8,3%) amostras mostraram-se dentro dos referidos padrões legais.

Avaliação, identificação e atividade enzimática de bactérias psicotróficas presentes no leite cru refrigerado

Extended storage of refrigerated milk can lead to reduced quality of raw and processed milk, which is a consequence of the growth and metabolic activities of psychrotrophic bacteria, able to grow under 7oC or lower temperatures. Although most of these microorganisms are destroyed by heat treatment, some have the potential to produce termoresistant proteolytic and lipolytic enzymes that can survive even UHT processing and reduce the processed products quality. Recently, the IN 51 determineds that milk should be refrigerated and stored at the farm what increased the importance of this group of microorganisms. In this work, psychrotrophic bacteria were isolated from 20 communitarian bulk tanks and 23 individual bulk tanks from dairy farms located at Zona da Mata region of Minas Gerais State and from southeastern Rio de Janeiro. Selected milk dilutions were plated on standard agar and after incubation for 10 days at 7oC, five colonies were isolated, firstly using nutrient agar and after using McConkey agar for 24 hours at 21oC. The isolates were identified by morphology, Gram stain method, catalase production, fermentative/oxidative metabolism and by API 20E, API 20NE, API Staph, API Coryne or API 50 CH (BioMerieux). In order to ensure reproductibility, API was repeated for 50% of the isolates. Species identification was considered when APILAB indexes reached 75% or higher. 309 strains were isolated, 250 Gram negative and 59 Gram positive. 250 Gram negative isolates were identified as: Acinetobacter spp. (39), Aeromonas spp. (07), A. Hydrophila (16), A. sobria (1), A. caviae (1), Alcaligenes feacalis (1), Burkholderia cepacia (12), Chryseomonas luteola (3), Enterobacter sp. (1), Ewingella americana(6), Hafnia alvei (7), Klebsiella sp. (1), Klebsiella oxytoca (10), Yersinia spp. (2), Methylobacterium mesophilicum (1), Moraxella spp. (4), Pantoea spp. (16), Pasteurella sp. (1), Pseudomonas spp. (10), P. fluorescens (94), P. putida (3), Serratia spp. (3), Sphigomonas paucomobilis (1). Five isolates kept unidentified. Pseudomonas was the predominant bacteria found (43%) and P. fluorescens the predominant species (37.6%), in accordance with previous reports. Qualitative analysis of proteolytic and lipolytic activity was based on halo formation using caseinate agar and tributirina agar during 72 hours at 21oC and during 10 days at 4°C, 10oC and 7°C. Among 250 Gram negative bacteria found, 104 were identified as Pseudomonas spp. and 60,57% of this group showed proteolytic and lipolytic acitivities over all four studied temperatures. 20% of Acinetobacter, Aeromonas, Alcaligenes, Burkholderia, Chryseomonas, Methylobacterium, Moraxella presented only lipolytic activity. Some isolates presented enzymatic activity in one or more studied temperatures. Among Gram positive bacteria, 30.51% were proteolytic and lipolytic at 10oC, 8.47% were proteolytic at 7oC, 10oC, and 21oC, 8.47% were proteolytic at all studied temperatures (4oC, 7oC, 10oC and 21oC) and 3.38% were proteolytic only at 21oC. At 4oC, only one isolate showed proteolytic activity and six isolates were lipolytic. In relation to Gram negative microorganisms, 4% were proteolytic and lipolytic at 7oC, 10oC and 21oC, 10% were proteolytic at 10oC and 4.4% were lipolytic at 4oC, 7oC, 10oC and 21oC, while 6.4% of all isolates were proteolytic and lipolytic at 10oC and 21oC as well as lipolytic at 4oC and 7oC. These findings are in accordance with previous researches that pointed out Pseudomonas as the predominant psycrotrophic flora in stored refrigerated raw milk

Diagnóstico regional do processo de queijo coalho comercializado em Natal/RN

Coalho cheese is a typical product of the Northeastern Brazil, which is consumed both raw and cooked. The present work aimed to study the characteristics of artisanal and industrial processes in the production of coalho cheese sold in Natal / RN in order to evaluate its quality and consumer s profile. Four artisanal cheeses plants were monitored and a questionnaire was sent to different cheese industries. Besides this, eight cheese samples (four artisanal and four industrial) were evaluated in regard to the microbiological quality, physical-chemical and sensory attributes. The sensory acceptance was evaluated by using 108 non-trained panelists by using the hedonic scale. The consumer s profile survey was applied to 400 consumers of coalho cheese. The lack of hygiene control was detected at the artisanal cheese production, which uses raw milk as its raw material. Research has shown that the industrialized cheeses are made from pasteurized milk provided by their own production or by a third party, as observed in cheese making dairies. In general, the results indicate variation in the manufacturing process of coalho cheese, which results in the lack of product standardization. Regarding the physical-chemical analysis, most artisanal and industrial samples presented moisture content between 36 and 40 %, classified as medium moisture cheese, which is the only parameter that showed no significant difference (p>0.05). However, the water activity (Aw), pH and acidity results differed significantly. All artisanal samples showed coliform contamination at 35 °C, which confirms the poor hygienic conditions. In regard to coliforms at 45 °C, 75 % of artisanal coalho cheese samples had value higher than 103 MPN / g, a value above the lawful limits determined by RDC nº 12. Fifty percent of industrial coalho cheese samples showed coagulase-positive Staphylococcus values above the limit allowed by the RDC nº 12, indicating poor handling. The sensory evaluation revealed that the taste was the only parameter that showed significant difference, and this difference was only between two industrial brands. The consumer s survey showed that the coalho cheese flavor is the most important reason for buying this kind of cheese. Although coalho cheese is mainly bought in supermarkets, open street markets and country shops are still important selling points. It is concluded that there is no coalho cheese standardization in the RN state, which leads to variations in physical-chemical and sensory attributes. Moreover, it is necessary greater hygiene control in the production and handling procedures of coalho cheese.

Avaliação de métodos de análises para determinação da contagem de células somáticas no leite cru, mantido em tanque de resfriamento

We analyzed the quality of raw milk from eight dairy farms in Rio Grande do Norte stored in a cooling tank , in order to evaluate methods for determining somatic cell counts (SCC). The Somaticell® kit and a portable Direct Cell Counter (DCC) were compared with each other and with the MilkoScanTM FT+ (FOSS Denmark), which uses Fourier Transform Infrared (FTIR) spectroscopy). Direct cell counter data were processed for somatic cell scores (log-transformed somatic cell count) and analyzed with the SAS®, statistical package , Statistical Analysis System, (SAS, INSTITUTE, 1998). Comparison of means and correlation of somatic cell scores were conducted using Pearson s correlation coefficient and the Tukey Test at 1 %. No significant difference was observed for comparison of means. The correlation between somatic cell scores was significant, that is, 0.907 and 0.876 between the MilkoScanTM FT+ and the Somaticell® kit and Direct Cell Count (DCC) respectively, and 0.943 between the Somaticell® kit and Direct Cell Count (DCC). The methods can be recommended for monitoring the quality of raw milk kept in a cooling tank in the production unit