Minas Fresh Cheese Research Articles

Preliminary Quantitative Microbial Risk Assessment for Staphylococcus enterotoxins in fresh Minas cheese, a popular food in Brazil

The main objective of this work was to assess the risk associated with staphylococcal enterotoxins (SE) intoxication after the consumption of fresh Minas cheese by the Brazilian population. Coagulase-positive staphylococci data from 350 samples were obtained from monitoring programs, and were used as a proxy for S. aureus contamination, considering that 73% of the strains were toxigenic. The Combined Database for Predictive Microbiology (ComBase) and the Pathogen Modeling Program (PMP) models were used to predict S. aureus growth rate and lag-phase in fresh Minas cheese at different pH, salt concentration and storage temperature in a household refrigerator, up to 7 days before consumption. Change in storage temperature had the largest impact on the growth rate and lag-phase obtained from both models. Cumulative probability of SE intake events equal to or higher than the toxigenic dose of 100 ng were calculated using Monte Carlo simulations performed by the @Risk software. The toxic dose was exceeded at the 99.95th percentile of exposure in the ComBase model (upper bound) for the adult population, the lowest percentile identified in the study. The S. aureus initial concentration was the parameter that most impacted the output obtained by @risk, indicating the importance of good manufacturing practices for fresh Minas cheese production, and proper storage conditions at the point of sale. This preliminary assessment indicated that the risk of staphylococcal intoxications from the consumption of fresh Minas cheese by the Brazilian population is probably low. The study identified many data gaps that needs to be addressed to improve the risk assessment.

AVALIAÇÃO FÍSICO-QUÍMICA, MICROBIOLÓGICA E SENSORIAL DE QUEIJO MINAS FRESCAL DE LEITE DE CABRA DESENVOLVIDO POR ACIDIFICAÇÃO DIRETA E FERMENTAÇÃO LÁTICA

O objetivo deste estudo foi avaliar o efeito da acidificação direta por ácido lático e por adição de cultura starter mesofílica tipo O (Lactococcus lactis subsp. lactis e Lactococcus lactis subsp. cremoris) nas propriedades físico-químicas, microbiológicas e sensoriais de queijo Minas frescal de leite de cabra. Duas formulações de queijo Minas frescal foram elaboradas por acidificação com ácido lático e com cultura mesofílica tipo O e avaliadas quanto a qualidade microbiológica, quantificando S. aureus, psicrotróficos, bactérias láticas, coliformes termotolerantes e quanto a presença de Salmonella sp. Quanto as análises físico-químicas, foram realizadas determinação de gordura, cinzas, umidade, acidez titulável em ácido lático e pH. As modificações físico-químicas no queijo Minas frescal foram avaliadas durante o período de estocagem de 14 dias e analisada a sua aceitabilidade e intenção de compra por meio da avaliação sensorial. Os resultados revelaram que ambas as formulações do queijo Minas frescal apresentavam-se em boas condições higiênico-sanitárias e de consumo. Quanto aos parâmetros físico-químicos, os teores de gordura, cinzas e umidade dos queijos não diferiram significativamente entre si (p < 0,05). O queijo obtido por acidificação direta por ácido lático foi o que apresentou menor contagem de bactérias láticas totais e acidez, maior valor de pH e maior aceitabilidade sensorial e intenção de compra diferindo do queijo obtido por fermentação lática. Os resultados mostram que a forma de acidificação afeta as características do produto e sua aceitação pelos consumidores. A utilização do leite de cabra para produção do queijo Minas frescal apresenta potencial de aplicação na indústria de lácteos, agrega valor, tornando-o um produto alternativo aos consumidores alérgicos ao leite bovino.

INFLUÊNCIA DA SUBSTITUIÇÃO PARCIAL DE CLORETO DE SÓDIO POR CLORETO DE POTÁSSIO EM QUEIJO MINAS FRESCAL DE LEITE DE OVELHA

O leite de ovelha apresenta elevados teores de gordura, proteína e minerais em relação ao leite de vaca, sendo indicado à produção de queijos, como o Minas frescal. Nas etapas de processamento do mesmo destaca-se a salga, por oferecer funções importantes para este produto. A salga é realizada pela adição de cloreto de sódio (NaCl), porém, em excesso, esse sal pode ser prejudicial à saúde do consumidor. Assim, elaborou-se três formulações de queijo Minas frescal de leite de ovelha (100% NaCl – QA; 75% NaCl e 25% de cloreto de potássio (KCl) – QB; 50% de NaCl e 50% KCl – QC) e avaliou-se as mesmas por análises físico-químicas, microbiológicas e sensoriais. A substituição parcial do NaCl por KCl não influenciou os teores de umidade, proteínas e cinzas, pH e atividade de água dos queijos. Ainda, a substituição de 50% do NaCl por KCl possibilitou a obtenção de um queijo com teor reduzido de sódio em relação ao padrão, com 100% de NaCl. A análise sensorial mostrou que a substituição de 50% (QC) e 25% (QB) de NaCl por KCl não apresentou diferença significativa para o índice de aceitação global, no entanto, o uso do KCl foi percebido pelos avaliadores, pois as formulações QB e QC diferiram significativamente do padrão (QA). Contudo, no teste de comparação múltipla não houve diferença significativa entre as amostras. Dessa forma, os resultados indicaram que a substituição parcial de NaCl por KCl pode ser realizada no queijo Minas frescal de leite de ovelha.

ACEITAÇÃO E CONSERVAÇÃO DE QUEIJOS FRESCOS ELABORADOS COM ÓLEOS ESSENCIAIS

O objetivo deste trabalho foi avaliar a aceitação e a conservação de queijos frescos tipo Minas frescal adicionados de óleos essenciais de orégano e gengibre na sua formulação. A qualidade do leite utilizado como matéria-prima foi avaliada quanto ao pH, acidez, alizarol, extrato seco total, densidade e carga microbiana total. Os queijos produzidos foram caracterizados quanto ao pH, acidez, umidade, lipídios, proteínas e cinzas. Os queijos foram avaliados sensorialmente através de testes afetivos utilizando escala hedônica e escala de atitude, visando determinar a aceitação e a intenção de compra pelos julgadores. Contagem de microrganismos mesófilos aeróbios totais foi utilizada para estimar o período de vida útil dos queijos. O leite utilizado como matéria-prima se apresentou dentro dos padrões de qualidade exigidos pela legislação. Os queijos produzidos com óleos essenciais apresentaram valores de pH e acidez em torno de 6,9 e 0,87%, respectivamente, 57,6% de umidade, 31,3% de lipídios, 11,4% de proteínas e 0,9% de cinzas. O queijo adicionado de óleo essencial de orégano e o controle foram os que receberam pelos julgadores os melhores valores para aceitação (7,5 e 7,6, respectivamente) e intenção de compra (4,2 e 4,4 respectivamente). Com relação à estimativa do tempo de vida útil, os queijos adicionados de óleo essencial de orégano e de gengibre apresentaram menores valores de carga microbiana total comparados com o controle (sem óleo) e o misto (adição dos dois óleos), apresentando valores de contagens acima de 106 UFC/g somente a partir do 28º dia de armazenamento.

QUALITY OF BUFFALO MILK SUPPLEMENTED WITH SELENIUM

This study aimed at evaluating the effects of a selenium enriched diet on the composition and somatic cell count of buffalo milk, along with verifying selenium residue in milk and in Minas fresh cheese. Data from 2264 Murrah buffalo milk samples belonging to Tapuio Ltda., located in the agreste region of Rio Grande do Norte were collected in the period from 2010 to 2014 for analysis. To verify the amount of selenium residue in buffalo milk and in Minas fresh cheese, 100 Murrah buffaloes were used and divided into 5 distinct treatment lots, according to milk production (0.08 ppm/Se/kg of concentrate). Three hundred mL of milk from each lot were collected from the tanks, as well as 300g of Minas fresh cheese, from August to November 2014, with collection of the treated lots held only in the month of November. Selenium supplementation reduces somatic cell count in buffalo milk. Selenium residue was not detected in buffalo milk or cheese. Studies with higher levels that 4.8 ppm of selenium in the diets of dairy buffaloes are recommended.

Effect of octenyl succinylated waxy starch as a fat mimetic on texture, microstructure and physicochemical properties of Minas fresh cheese

The effect of fat reduction and the addition of octenyl succinylated (OS) waxy maize starch as a fat replacer on the physicochemical properties, texture, and microstructure of Minas fresh cheese was studied. The cheeses were produced according to three formulations: full-fat cheese (FC), reduced-fat cheese (RC), and reduced-fat cheese with 0.5 kg/100 L of added starch (SC). Analyses of the chemical composition, titratable acidity, water-holding capacity (WHC), yield, texture, microstructure, and electrophoretic profile of casein were conducted. Fat reduction increased the hardness and decreased the yield of the cheeses. Fat reduction also promoted a denser microstructure and less proteolysis. The concentration of starch that was added was insufficient to improve the yield and texture parameters of the reduced-fat cheese. However, the addition of starch increased the moisture content and the WHC of the reduced-fat cheese. In general, OS waxy maize starch improved the overall quality of the reduced-fat Minas fresh cheese.

Nutritional and sensory characteristics of Minas fresh cheese made with goat milk, cow milk, or a mixture of both

This study aimed to assess and compare the nutritional, technological, and sensory characteristics of Minas fresh cheese made with goat milk, cow milk, or a mixture of the two stored in cold conditions for 21d. The yield and centesimal composition of the cheeses were not affected by the type of milk used in their preparation. Reductions were observed in the moisture content, pH, proteolysis index, and instrumental hardness; moreover, increases were observed in the syneresis, acidity index, and depth of proteolysis index in all cheeses. The percentages of caprylic, capric, oleic, and linoleic fatty acids were higher in goat milk cheese and cheese made with a mixture of goat and cow milk compared with cow milk cheese, and a sensory evaluation revealed differences in color, flavor, and aroma between the cheeses. The preparation of Minas fresh cheese with a mixture of goat and cow milk can be a viable alternative for dairy products in the market that can be characterized as high-quality products that meet consumer demands.

Action of lactoferrin on the multiplication of Lactobacillus casei in vitro and in Minas fresh cheese

O presente estudo avaliou a atividade da lactoferrina sobre a multiplicação de Lactobacillus casei probiótico in vitro e no queijo Minas frescal. As curvas de crescimento de L. casei em caldo BHI contendo lactoferrina nas concentrações de 1 mg/mL and 2 mg/mL foram construídas. Adicionalmente, os queijos Minas frescal contendo somente L. casei (controle) e L. casei e a lactoferrina (2 mg/g e 4 mg/g) foram produzidos e armazenados a 5°C durante 28 dias. Foram realizadas as análises de pH, acidez livre titulável e enumeração de L. casei e microrganismos psicrotróficos no dia 1 (dia da produção) e após 7, 14, 21 e 28 dias de armazenamento. Além disso, no dia 1, foram realizadas as análises de composição centesimal. Os experimentos foram realizados em triplicata e os dados obtidos foram analisados utilizando-se ANOVA e teste de Tukey a 5% de significância. Nos ensaios in vitro a multiplicação de L. casei foi estimulada pela presença da lactoferrina na concentração de 2 mg/mL. Entretanto, esta atividade não foi observada no queijo, mesmo quando a concentração de 4 mg/g de lactoferrina foi utilizada. A população de microrganismos psicrotróficos presentes nos queijos adicionados de lactoferrina não diferiram das populações observadas para os queijos controle (P>0,05), demostrando que não houve atividade antimicrobiana nos produtos. Estudos futuros devem ser conduzidos para avaliar os efeitos antimicrobianos da lactoferrina em alimentos, pois são muitas as variáveis que afetam a atividade desta proteína quando comparados aos resultados obtidos in vitro.

Application of bacteriocinogenic Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch in the control of Listeria monocytogenes in fresh Minas cheese

Several strains of Enterococcus spp. are capable of producing bacteriocins with antimicrobial activity against important bacterial pathogens in dairy products. In this study, the bacteriocins produced by two Enterococcus strains (Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch), isolated from cheeses, were characterized and tested for their capability to control growth of Listeria monocytogenes 426 in experimentally contaminated fresh Minas cheese during refrigerated storage. Both strains were active against a variety of pathogenic and non-pathogenic microorganisms and bacteriocin absorption to various L. monocytogenes, Enterococcus faecalis ATCC 19443 and Lactobacillus sakei ATCC 15521 varied according to the strain and the testing conditions (pH, temperature, presence of salts and surfactants). Growth of L. monocytogenes 426 was inhibited in cheeses containing E. mundtii CRL35 up to 12 days at 8 °C, evidencing a bacteriostatic effect. E. faecium ST88Ch was less effective, as the bacteriostatic affect occurred only after 6 days at 8 °C. In cheeses containing nisin (12.5 mg/kg), less than one log reduction was observed. This research underlines the potential application of E. mundtii CRL35 in the control of L. monocytogenes in Minas cheese.

Effect of the inoculation level of Lactobacillus acidophilus in probiotic cheese on the physicochemical features and sensory performance compared with commercial cheeses

The complex metabolism of probiotic bacteria requires several technological options to guarantee the functionally of probiotic dairy foods during the shelf life. This research aimed to evaluate the effect of the supplementation of increasing amounts of Lactobacillus acidophilus (0, 0.4, or 0.8g/L of milk) on the physicochemical parameters and sensory acceptance of Minas fresh cheese. In addition, the sensory acceptance of probiotic cheeses was assessed using a consumer test and compared with commercial cheeses (conventional and probiotic). High counts (9.11 to 9.42 log cfu/g) of L. acidophilus were observed throughout the shelf life, which contributed to the maintenance of its probiotic status and resulted in lower pH values and greater production of organic acids. The probiotic cheeses presented lower scores for appearance, aroma, and texture compared with conventional cheeses. Internal preference mapping explained almost 60% of the total variation of the data and showed a large number of consumers concentrated near the conventional cheeses, demonstrating greater preference for these samples. The findings indicated that some negative sensory effects could occur when high level of supplementation with L. acidophilus is used in probiotic cheese processing.

Manufacture of low-sodium Minas fresh cheese: Effect of the partial replacement of sodium chloride with potassium chloride

We investigated the effect of sodium reduction by partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on the manufacture of Minas fresh cheese during 21 d of refrigerated storage. Four treatments of low-sodium Minas fresh cheese were manufactured, with partial replacement of NaCl by KCl at 0, 25, 50, and 75% (wt/wt), respectively. The cheeses showed differences in the content of moisture, ash, protein, salt, and lipid contents, as well as on the extent of proteolysis and hardness throughout the storage period. However, no difference was observed among treatments within each storage day tested. The partial substitution of NaCl by KCl decreased up to 51.8% the sodium concentration of the cheeses produced. The consumer test indicated that it is possible to manufacture a low-sodium Minas fresh cheese that is acceptable to consumers by partial substitution of NaCl by KCl at 25% (wt/wt) in the salting step.

Musca domestica L. como vetor de microrganismos patogênicos para queijo Minas Frescal Ultrafiltrado

Summary Musca domestica L. (Diptera: Muscidae) is recognized as an important agent in the transmission and spread of infectious food-borne diseases. In this work, the microbiological analyses of a fly population collected in the ambience used to manufacture artisan fresh Minas cheese, revealed large numbers of mesophilic microrganisms and total coliforms. Escherichia coli and Salmonella spp. were identified in this population but Listeria monocytogenes and Staphylococcus aureus were not detected. The transmission of these microrganisms to Ultra-Filtered fresh Minas (UF) was evaluated by two procedures: contact with the flies (cheese + contact) and addition of the flies to the (cheese + broth). In both samples of cheese, large numbers of mesophilic microrganisms (between 3.5 x 10 5 and 2.2 x 10 9 CFU.mL -1 ) and total coliforms (≥2.4 x 10 3 MPN.mL -1 ) were found, and the presence of E. coli and Salmonella spp. in these populations confirmed. The cheese control samples (no contact with the flies) showed low counts of mesophilic microrganisms (<25 CFU.mL-1 ) and total coliforms (<3 MPN.mL-1 ) and absence of the pathogens E. coli and Salmonella spp. It was concluded that, whatever the form of contact, the pathogenic microrganisms loaded by flies survived in UF fresh Minas cheese, remaining viable during the storage of the product at 10oC for 14 days.

Estudo da vida útil de queijo Minas

Foi avaliado o prazo de vida útil do queijo Minas frescal armazenado a 4 °C por 30 dias, através de análises microbiológicas e físico-químicas. Três lotes (A, B e C) de uma mesma marca foram analisados nos dias 1, 10, 20 e 30 após a fabricação. Foram feitas as contagens de microrganismos psicrotróficos, lipolíticos, proteolíticos, bactérias lácticas e mesófilas, que apresentaram um crescimento contínuo durante o período, atingindo contagens médias, respectivamente:, piscotróficos = 11,63; lipolíticos = 10,34; proteolíticos = 9,75 bactérias lácticas = 9,53; e mesófilos = 11,47 log UFC.g-1. A população de Escherichia coli desenvolveu-se em um dos lotes e Staphylococcus coagulase + e Salmonella não foram detectados. No mesmo período, observou-se a redução de 0,81 no valor do pH e o aumento do ácido láctico (0,026%). Não se observou redução na gordura (21,5%), embora a quantidade de ácidos graxos livres tenha aumentado em 0,22 mg KOH.g-1 de gordura. A proteína variou de 21,30 a 22,10% sem diferença significativa. O índice de extensão da proteólise aumentou 3% a cada 10 dias. Apenas em um dos lotes (C) no 30º dia o produto apresentou-se impróprio para o consumo com 1,7 x 10(4) NMP.g-1 de E. coli.

Viability of Lactobacillus acidophilus La-5 added solely or in co-culture with a yoghurt starter culture and implications on physico-chemical and related properties of Minas fresh cheese during storage

The effect of a probiotic culture of Lactobacillus acidophilus (La-5), added solely or in co-culture with a starter culture of Streptococcus thermophilus, on texture, proteolysis and related properties of Minas fresh cheese during storage at 5 °C was investigated. Three cheese-making trials were prepared and produced with no addition of cultures (T1 – control), supplemented with La-5 (T2), and with La-5 + S. thermophilus (T3). Viable counts of La-5 remained above 6.00 log cfu g −1 during the whole storage for T2, reaching 7.00 log cfu g −1 on the 14th day. For T3, the counts of La-5 remained above 6.00 log cfu g −1 after 7 days of storage. Due to the presence of S. thermophilus, T3 presented the highest proteolytic index increase and titratable acidity values. Nevertheless, these results and S. thermophilus addition had no influence on viability of La-5 which presented satisfactory populations for a probiotic food. Moreover, the use of a yoghurt culture for the production of Minas fresh cheese T3 supplemented with La-5 resulted in a good quality product, with a small rate of post-acidification, indicating that traditional yoghurt culture could be employed in co-culture with La-5 to improve the quality of this cheese.

Sensory evaluation of probiotic Minas fresh cheese with Lactobacillus acidophilus added solely or in co‐culture with a thermophilic starter culture

SummarySensory acceptance of formulations of probiotic Minas fresh cheese was investigated. Cheeses were prepared and supplemented with Lactobacillus acidophilus (T1 – probiotic), Lactobacillus acidophilus + Streptococcus thermophilus (T2 – probiotic + starter) or produced with no addition of cultures (T3 – control). Sensory acceptance tests were performed after 7 and 14 days of storage at 5 °C, using a 9‐point hedonic scale (1 = dislike extremely; 9 = like extremely). After 7 days, no significant difference was detected among cheeses T1, T2 and T3 (P &gt; 0.05). After 14 days, cheeses T1 and T2 presented higher acceptance and differed significantly from cheeses T3. Cheeses T3 presented significant difference between 7 and 14 days of storage (P &lt; 0.05), whereas probiotic cheeses T1 and T2 were stable in the same period (P &gt; 0.05). The addition of L. acidophilus, either solely or in co‐culture with a thermophilic starter culture, resulted in good acceptance of Minas fresh cheese, improving sensory performance of the product during storage.

Condições de processamento e comercialização de queijo-de-minas frescal

Avaliaram-se a evolução da contaminação microbiana de queijo-de-minas frescal durante sua vida de prateleira e a padronização e qualidade de sete marcas (A a G) de queijo (3 a 4 lotes de cada), adquiridas em supermercados de São Paulo. Os parâmetros determinados incluíram contagens de Staphylococcus spp., coliformes, Escherichia coli e bactérias láticas, pH, umidade e dureza instrumental, após 7, 14 e 21 dias de fabricação dos queijos. Avaliou-se, também, o comportamento da população de coliformes e E. coli durante o processamento de queijo-de-minas frescal com leite pasteurizado e cru. As contagens mais elevadas de Staphylococcus spp., coliformes e E. coli detectadas foram, respectivamente, 7,83 (B), 8,02 (B) e 7,83 log UFC/g (C). Todas as marcas, exceto a F, apresentaram índices de contaminação acima do recomendável. Seis das sete marcas apresentaram-se impróprias para o consumo já aos sete dias de fabricação. As populações de coliformes e de E. coli dos queijos preparados no laboratório aumentaram 2,5 ciclos log durante o processamento com leite pasteurizado e 4,5 ciclos log (coliformes) e 5 ciclos log (E. coli) em queijo fabricado com leite cru. Uma reavaliação das condições de fabricação, distribuição, comercialização e prazo de validade de queijo-de-minas frescal é necessária.

Incorporation of Lactobacillus acidophilus in Minas fresh cheese and its implications for textural and sensorial properties during storage

Abstract The effect of Lactobacillus acidophilus on instrumental texture profile and related properties of Minas fresh cheese during storage at 5 °C and on sensory performance was investigated. Four cheese-making trials were prepared, two supplemented with a mesophilic type O culture (T1, T2) and two with lactic acid (T3, T4). L. acidophilus was added in T2 and T3. The viability of L. acidophilus, instrumental texture profile analysis and related properties were monitored during storage for up to 21 days. Probiotic cheeses T3 were firmer by the end of storage, due to higher values of pH and hardness. Differences detected were attributed to the starter, rather than to L. acidophilus. Viability of L. acidophilus during storage ranged from 6.04 to 6.93 for T2 and from 5.46 to 6.53 log cfu g−1 for T3, which performed better in sensory evaluation. Minas fresh cheese is a suitable food system for the delivery of L. acidophilus.

Probiotic potential of Minas fresh cheese prepared with the addition of Lactobacillus paracasei

The effect of a probiotic Lactobacillus paracasei culture on sensory performance and on the behaviour of instrumental texture profile and related properties of Minas fresh cheese during storage at 5 oC was investigated. Four cheese-making trials were prepared, two supplemented with a mesophilic type O lactic culture (T1, T2) and two with lactic acid (T3, T4). L. paracasei subsp. paracasei was added in T2 and T3. The viability of L. paracasei, instrumental texture profile analysis and related properties were monitored during storage for up to 21 days. Viable counts of L. paracasei in probiotic cheeses T2 and T3 started above 10 6–10 7 cfu g −1 and increased during storage. Cheeses T1 and T2 differed significantly from T3 and T4 in relation to hardness, cohesiveness, chewiness and gumminess ( P<0.05). Probiotic cheeses T3 performed better in sensory evaluation. Minas fresh cheese with L. paracasei showed a great potential as a functional food.

Avaliação dos laudos analíticos das amostras de alguns tipos de queijo recebidos pelo Instituto Adolfo Lutz

With the purpose of estimate the quality of the cheeses commercialized in Ribeirao Preto, were analysed the laboratorial results from the period of 1989-1990, in this Institute. Were studied 61 cheeses analysis of the kinds: Minas Fresh, Mozzarella, Swiss Type and Cream cheese. From these, 6 were related to frauds, 10 were approved and 45 condemned, among these, 13 were type Minas Fresh for what only one (7,70%) was approved. From 9 samples of Mozzarela cheeses, only 2 (22,22%) were approved. From 25 samples of Swiss Type, only 1 (4,0% was approved and 24 (96,0%) were condemned. By other way, from 8 samples of Cream Cheeses, 6 (75,0%) were aproved or the majotity. Then, from the 55 samples studied, with exception of the frauds, only 10 (18,18%) were approved, so we concluded not to be satisfatory the quality of cheeses in this period of time.