Yeasts and hygienic-sanitary microbial indicators in water buffalo mozzarella produced and commercialized in Minas Gerais, Brazil

The aim of this work was to study the yeast populations and the main hygienic-sanitary microbial indicators in water buffalo mozzarella produced and commercialized in Minas Gerais, Brazil. Forty-two water buffalo mozzarella samples were purchased from retail outlets in Belo Horizonte. In addition, five samples of consecutive starter cultures, curd before acidification, acidified curd and mozzarella were collected at an industry in the city of Oliveira. Only three of the five water samples analyzed were suitable for consumption according to Brazilian sanitary standards. Four milk samples were highly contaminated with fecal coliforms, and did not meet the minimal hygienic-sanitary standards according to Brazilian regulations. Only one sample of buffalo muzzarela purchased from retail outlets exceeded the limit for coagulase-positive Staphylococcus. Eleven samples showed counts of thermotolerant coliforms higher than5x 10³ CFU.g-1, but still lower than the maximum permitted by the Brazilian laws. Salmonella spp. and Listeria monocytogenes were not isolated. Debaryomyces hansenii, Candida lusitaniae and C. parapsilosis were the prevalent yeast species isolated from cheese. Among samples from the production stages, the acidified curd presented the highest numbers of yeasts, with C. catenulata being the most frequent species isolated. Some opportunistic yeast species such as C. guilliermondii, C. tropicalis, C. parapsilosis, C. lusitaniae, C. catenulata, C. rugosa and C. krusei occurred in the mozzarella cheese samples analyzed. The mozzarella cheese presented a low microbial load as compared to other cheese already studied, and the yeast biota included species typical of cheese and also opportunistic pathogens.

Methods for thermal inactivation of pathogens in mozzarella: a comparison between stretching and pasteurization / Métodos para inativação térmica de patógenos em mozarela: comparação entre filagem e pasteurização

This study aimed to evaluate the efficiency of stretching in the reduction of pathogens when compared to milk pasteurization, the official method to ensure safe cheese production. Whole buffalo milk was contaminated with Mycobacterium fortuitum, Listeria monocytogenes, Salmonella typhimurium, and Staphylococcus aureus. Part of the milk was used in mozzarella production and the other part was submitted to holder pasteurization. Pathogens were quantified before and after thermal processing (mozzarella stretching and milk pasteurization). Pasteurization and stretching led to the following reductions in log cycles, respectively: 4.0 and 6.3 for Mycobacterium sp.; 6.0 and 8.4 for Listeria sp.; >6.8 and 4.5 for Staphylococcus sp.; and >8.2 and 7.5 for Salmonella sp.

Este estudo teve como objetivo avaliar a eficácia da filagem na redução de patógenos,em comparação coma pasteurizaçãodo leite, que é o método oficialpara garantir aprodução de queijos seguros. Leite de búfala integral foi contaminado com Mycobacterium fortuitum, Listeria monocytogenes, Salmonella typhimurium e Staphylococcus aureus. Parte desse leite foi empregada na fabricação da mozarela e outra parte foi submetida à pasteurização lenta. Os patógenosforam quantificadosantes e após os processos térmicos (filagem da mozarela e pasteurização do leite). As reduções, em ciclos logarítmicos, causadas pela pasteurização e pela filagem, respectivamente, foram: 4,0 e 6,3 de Mycobacterium sp., 6,0 e 8,4 de Listeria sp., >6,8 e 4,5 de Staphylococcus sp. e >8,2 e 7,5 de Salmonella sp.

Características físico-químicas e sensoriais de marcas comerciais de queijo mozarela de leite de búfala / Physical-chemical and sensorial characteristics of marketed buffalo mozzarella cheese

No presente estudo foram avaliados os parâmetros físico-químicos e sensoriais de oito marcas de queijo Mozarela de búfala, analisando-se os teores de umidade, extrato seco total, lipídios, lipídios no extrato seco, proteínas, proteínas no extrato seco, cinzas, carboidratos, pH, digestibilidade in vitro de proteínas e β-caroteno. Realizou-se a análise instrumental da cor por meio de colorímetro Kônica Minolta CR 400. Sob o aspecto sensorial, foram feitos testes de ordenação de cor (branco claro – escuro), maciez (menos –mais), efetuados por 30 provadores, e preferência (gostei menos – gostei mais), realizado por 55 pessoas. As amostras de queijos analisadas apresentaram diferenças significativas nos parâmetros avaliados, com exceção da digestibilidade in vitro. Observou-se também a ausência de β-caroteno nas amostras de todas as marcas, o que indica que estão em conformidade com a legislação. Verificou-se que a variação na tonalidade branca não afetou a preferência, o que sugere que as marcas de produtos mais macios foram as mais aceita se que as variações encontradas estejam provavelmente associadas à variação da composição química da matéria-prima, bem como à forma de processamento do produto.

The sensorial and physical-chemical parameters of eight brands of buffalo mozzarella cheese were assessedanalyzing humidity rate, total dry extract, lipids, lipids in dry extract, proteins, proteins in dry extract, ashes, carbohydrates, pH, in vitro digestibility of proteins and β-carotene. The instrumental color analysis was performed by using Konica Minolta colorimeter CR 400. Sensorial color ordination tests (light – dark), softness (less - more) and preference (liked less – liked more) were performed by 30 testers, and the preference test by 55 persons. The cheeses samples from different brands showed significant differences in the evaluated parameters, except for in vitro digestibility. It was also found a lack of β-carotene in all of product brands, being in agreement with the legislation in force. The range of white tonality did not affect the preference; therefore, it was inferred that the softest product brands were the best accepted andthe softness variations were probably related to the chemical composition of raw material and also to the procedure for manufacturing the product.

Increased presevation of sliced mozzarella cheese by antimibrobial sachet incorporated with allyl isothiocyanate

There is an increasing tendency to add natural antimicrobials of plant origin into food. The objective of this work was to develop a microbial sachet incorporated with allyl isothiocyanate (AIT), a volatile compound of plant origin, and to test its efficiency against growth of yeasts and molds, Staphylococcus sp. and psychrotrophic bacteria on sliced mozzarella cheese. Another objective was to quantify the concentration of AIT in the headspace of cheese packaging. A reduction of 3.6 log cycles was observed in yeasts and molds counts in the mozzarella packed with the antimicrobial sachet over 15-day storage time. The sachet also showed an antibacterial effect on Staphylococcus sp., reducing 2.4 log cycles after 12-day storage. Psychrotrophic bacteria species were the most resistant to the antimicrobial action. The highest concentration of AIT (0.08µg.mL-1) inside the active packaging system was observed at the 6-day of storage at 12 ºC ± 2 ºC. At the end of the storage time, AIT concentration decreased to only 10 percent of the initial concentration. Active packaging containing antimicrobial sachet has a potential use for sliced mozzarella, with molds and yeasts being the most sensitive to the antimicrobial effects.

Composition, functional properties and sensory characteristics of Mozzarella cheese manufactured from different somatic cell counts in milk

In the present study, composition, functional properties and sensory characteristics of Mozzarella cheese produced from milk with somatic cell counts (SCC) at low (<200,000 cells/mL), intermediate (≈400,000 cells/mL) and high (>800,000 cells/mL) levels were investigated. Three batches of cheese were produced for each SCC category. The cheeses were vacuum packed in plastic bags and analysed after 2, 9, 16, 23 and 30 days of storage at 4ºC. SCC level did not affect the moisture, fat, total protein and ash content, mesophilic and psychrotrophic bacteria, and sensory parameters of Mozzarella cheese. However, meltability increased in cheese manufactured from high SCC milk. Results indicated that raw milk used to produce Mozzarella cheese should not contain high SCC (>800,000 cells/mL) in order to avoid changes in the functional properties of the Mozzarella cheese.

No presente estudo foram investigadas a composição, as propriedades funcionais e as características sensoriais do queijo Mussarela produzido a partir de leite com contagens de células somáticas (CCS) em níveis baixos (<200.000 CS/mL), intermediários (≈400.000 CS/mL) e altos (>800.000 CS/mL). Foram produzidos 3 lotes de queijo para cada CCS. Os queijos foram embalados a vácuo e analisados após 2, 9, 16, 23 e 30 dias de armazenamento a 4ºC. O nível de CS não afetou a umidade, os teores de gordura, proteína total e cinzas, os níveis de bactérias mesófilas e psicrotróficas, e os parâmetros sensoriais do queijo Mussarela. Entretanto, houve aumento da capacidade de derretimento no queijo fabricado com leite de alta CCS. Os resultados indicam que o leite cru utilizado para a produção de queijo Mussarela não deve conter níveis de CS acima de 800.000/mL, para evitar alterações nas propriedades funcionais do queijo Mussarela.

Perfil físico-químico do soro de queijos mozarela e minas-padrão produzidos em várias regiões do estado de Minas Gerais / Physical-chemical profile of the whey of minas-padrão and mozzarella cheeses produced in some regions of Minas Gerais state

O perfil físico-químico de soros de queijos mozarela e minas-padrão foi analisado em quatro das cinco macrorregiões com maior produção desses queijos no estado de Minas Gerais: Alto São Francisco, Zona Metalúrgica, Zona da Mata e Sul de Minas. Os valores média+desvio padrão encontrados para os componentes do soro de queijo mozarela foram: -0,565+0,031ºH para crioscopia; 6,19+0,26 para pH; 13,16+3,08ºD para acidez; 6,33+0,43g/100g para sólidos totais; 93,67+0,43g/100g para umidade; 0,77+0,26g/100g para gordura; 0,84+0,04g/100g para proteína; 4,42+0,68g/100g para lactose; 0,47+0,04g/100g para cinzas; 0,18+0,01g/100g para cloretos e 1,0253+0,0006 para densidade. Para soro de queijo minas-padrão, foram encontrados: -0,555+0,030ºH para crioscopia; 6,30+0,31 para pH; 12,48+2,07ºD para acidez; 6,28+0,51g/100g para sólidos totais; 93,97+0,54 g/100g para umidade; 0,70+0,21g/100g para gordura; 0,49+0,03g/100g para cinzas; 4,12+0,36 g/100g para lactose; 0,80+0,04g/100g para proteínas; 0,20+0,01g/100g para cloretos e 1,0249+0,0009 para densidade. Não houve diferença significativa entre os dois tipos de soro, mas encontrou-se diferença entre os soros de diferentes regiões para crioscopia, sólidos totais, umidade e densidade, e observou-se interação tipo de soro versus região para proteínas, acidez, gordura e cloretos. Os teores de lactose e resíduo mineral fixo (cinzas) não apresentaram nenhuma diferença significativa. Por não existir um padrão de identidade e qualidade específico para soros de queijo, esses resultados podem ser tomados como base para se desenvolver tais padrões.

The physical-chemical profile of the whey of mozzarella and minas-padrão cheeses was studied in four regions ("Alto São Francisco", "Zona Metalúrgica", "Zona da Mata" and "Sul de Minas") which produce milk and cheese in Minas Gerais. Due to the lack of a specific identity and a quality pattern for cheese whey, the results can be taken as a base to develop such patterns. The mean values found for mozzarella cheese whey were: - 0.565± 0.031ºH for freezing point; 6.19± 0.26 for pH; 13.16± 3.08ºD for titratable acidity; 6.33± 0.43g/100g for total solids; 93.67± 0.43g/100g for moisture; 0.77± 0.26g/100g for fat; 0.84± 0.04g/100g for protein; 4.42± 0.68g/100g for lactose; 0.47± 0.04 g/100g for ashes; 0.18± 0.01g/100g for chlorine and 1.0253± 0.0006 for density. In relation to minas-padrão cheese whey, the following mean results were obtained: - 0.555± 0.030ºH for freezing point; 6.30± 0.31 for pH; 12.48± 2.07ºD for titratable acidity; 6.28± 0.51g/100g for total solids; 93.97± 0.54 g/100g for moisture; 0.70± 0.21g/100g for fat; 0.80± 0.04g/100g for protein; 4.12± 0.36g/100g for lactose; 0.49± 0.03g/100g for ashes; 0.20± 0.01g/100g for chlorine and 1.0249± 0.0009 for density. No statistical difference between those types of whey was observed, but difference among wheys from regions for freezing point, total solids, moisture and density as well as interaction whey x regions for protein, titratable acidity, fat, and chorine were found. Only lactose and ash contents did not present any statistical difference.

Responses to selection for milk traits in dairy buffaloes

The aim of the present study was to estimate the index and individual responses to selection for milk (MY), fat (FY) and protein (PY) yields for different breeding goals for two commercial buffalo milk production systems in São Paulo State characterized by: 1) all milk produced is sold to the industry (MILK) and 2) all milk produced is used in the mozzarella cheese-making process at the farm (MOZZARELLA). The current payment policy is based exclusively on milk volume. The mozzarella price refers to the wholesale selling price. Index responses to selection (IR) were calculated for three different breeding goals (BG): 1) MY exclusively (BG(1)); 2) FY + PY (BG(2)) and 3) MY + FY + PY (BG(3)). IR for the MILK system were 41.79 US dollars (BG(1)), 5.91 US dollars (BG(2)) and 38.22 US dollars (BG(3)). For the MOZZARELLA system, IR were 179.50 US dollars (BG(1)), 262.85 US dollars (BG(2)) and 402.41 US dollars (BG(3)). The results suggest that for the present circumstances, selection for milk components is not advantageous when milk is produced for sale to the industry. However, when mozzarella making is added to the system, the selection for components and milk volume is the most economically beneficial.