Avaliação das propriedades de coagulação de leite bovino in natura por parâmetros latodinamográficos e reológicos

Orientadora : Profª. Drª. Nina WaszczynskyjCoorientador : Prof. Dr. Alessandro NogueiraTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Alimentos. Defesa: Curitiba, 13/12/2017Inclui referências : f. 87-100Resumo: A produção de leite é uma atividade importante em diversos países do mundo. No Brasil, 4º maior produtor mundial (ano de 2015), o leite está entre os principais produtos da agropecuária. Com o aumento no volume de leite, a produção de derivados lácteos como os queijos vem crescendo. Porém, nem todo leite é adequado para produção de queijo, alguns são mais aptos à coagulação que outros, sendo sua composição e algumas características como as propriedades de coagulação do leite (PCL) fatores importantes para o processo tecnológico e para o rendimento econômico do laticínio. Desta forma, é interessante estudar e avaliar a capacidade de coagulação do leite a fim aperfeiçoar o destino do mesmo, bem como contribuir com estudos para melhoria genética de bovinos de leite. O presente estudo foi composto pela revisão de literatura e dois experimentos. No experimento 1 foram analisadas amostras de leite provenientes de vacas da raça Holandesa de seis rebanhos distintos da província de Veneza-Itália, em dois períodos do ano: verão (julho a setembro) e outono (setembro a dezembro). Todas as amostras foram submetidas às análises de gordura, proteína total, caseína, pH por espectroscopia no infravermelho médio; contagem de células somáticas por fluorescência ótica e propriedades de coagulação do leite, expressas em tempo para o início da coagulação enzimática (TCE, min) e consistência do coágulo após 30 minutos da adição do coalho (A30, mm) por latodinamografia. Foram também determinados os índices de aptidão de coagulação do leite (IAC) e de temperatura e umidade (ITU). Do total de amostras analisadas, 41,2% não coagularam (NC) nos 30 minutos de análise. O maior percentual de amostras coaguladas foi para as coletadas durante o outono, período que os valores para o ITU foram mais baixos. Os dados obtidos nesse trabalho demonstram um elevado número de amostras NC, constando-se que provavelmente as condições climáticas influenciaram a capacidade de coagulação. No experimento 2 foram avaliadas amostras de leite de dezessete animais das raças Holandesa e mestiças Jersey-Holanda de um rebanho localizado na cidade de Ponta Grossa, Paraná-Brasil. Foram analisadas as propriedades reológicas da coagulação enzimática do leite, em três períodos do ano (maio, agosto e dezembro). O teor de gordura, proteína total, caseína, lactose, contagem de células somáticas e o ITU foram determinadas pelos mesmos procedimentos do experimento 1 e o pH com uso de pHmetro. As propriedades reológicas (tempo de coagulação enzimática e a força da coalhada) foram determinadas por reometria em regime oscilatório de baixa amplitude por meio dos módulos G' (de armazenamento), G'' (de perda) e da tan ? (tangente de perda). A partir de amostras do sangue dos animais, foram determinados os genótipos para ?appa-caseína (?-CN), betacaseína (?-CN) e beta-lactoglobulina (?-Lg) pela técnica de PCR-RFLP. Foram encontradas diferenças entre a composição dos leites nos diferentes períodos de análise, bem como no perfil reológico. Com exceção das amostras de leite de um animal, ambos G' e G'' aumentaram com o tempo, comportamento esperado e de acordo com a literatura, porém apresentaram característica de gel fraco. Com relação ao perfil proteico foram encontrados os genótipos AA; AB e BB para ?-CN; A1A2 e A2A2 para a ?-CN e AA; AB e BB para ?-Lg, porém não foi estabelecida uma relação direta com as propriedades de coagulação e com o TCE. Os resultados obtidos nos 2 experimentos apontam a necessidade de estudos com relação à PCL a fim de garantir um leite de qualidade para a produção de queijos e que a determinação do teor de proteína total ou caseína não são suficientes para determinar essas propriedades. Também foi possível notar que o estresse térmico tem influência negativa sobre a PCL. Para indústria de queijos, longo TCE é o resultado de reduzida velocidade de formação do coágulo com fraca consistência final o que pode resultar em perdas no rendimento e na qualidade global principalmente para queijos maturados. Palavras-chave: Coagulação do leite. Tempo de coagulação. Reologia. Queijos.Abstract:Milk production is an important activity in various countries throughout the world. In Brazil, the 4th largest world producer (year 2015), milk is amongst the main agricultural products, and with the increase in the milk volume, the production of dairy products such as cheeses has also grown. However not all milk is adequate for cheese production, some being more apt for coagulation than others. Thus for cheese production the composition of the milk and some of its characteristics, such as the milk coagulation properties (MCP), are important for the technological process and for the economic yield of the dairy. It is therefore of interest to study and evaluate the coagulation capacity of the milk so as to perfect its destiny, and contribute to studies for the genetic improvement of dairy cattle. The present study consisted of two experiments. In the first experiment milk samples from Holstein cows in six distinct herds in the province of Venice-Italy in two periods of the year: summer (July to September) and autumn (September to December), were analyzed. All the samples were analyzed for their fat, total protein and casein contents and pH value by medium infrared spectroscopy; somatic cell count by optical fluorescence; and the milk coagulation properties by lactodynamography and expressed as the milk rennet coagulation time (RCT, min) and curd firmness (A30, mm), 30 minutes after the addition of the rennet. The milk coagulation aptitude index (IAC) and temperature-humidity index (THI) were also determined. Of the total number of samples analyzed, 41.2% did not coagulate (NC) during the 30 minutes of analysis. The majority of the samples that did coagulate were taken in the autumn, period during which the THI values were lower. The data obtained in this study demonstrated an elevated number of NC samples, so probably the climatic conditions influenced the coagulation capacity. In experiment 2, milk samples from seventeen animals of Holstein and mixed Jersey-Holstein breeds from a herd located in the city of Ponta Grossa, Paraná, Brazil, were evaluated. The rheological properties of the milk rennet coagulation were analyzed at three periods during the year (May, August and December). The fat, total protein and casein contents and the somatic cell counts and THI were determined using the same procedures used in experiment 1 and the pH measured using a pHmeter. The rheological properties (rennet coagulation time and curd firmness) were determined by rheometry using a low amplitude oscillatory regime by way of the storage modulus (G'), loss modulus (G") and the loss tangent (tan ?). The genotypes for ?appa-casein (?-CN), beta-casein (?-CN) and beta-lactoglobulin (?-Lg) were determined from the animals' blood samples using the PCR-RFLP technique. Differences were found in the compositions of the milks obtained during the different periods of analysis, and also in the rheological profiles. With the exception of the milk samples from one animal, the values for both G' and G" increased with time, behavior expected and in agreement with the literature, since they present the characteristics of a weak gel. With respect to the protein profile the following genotypes were found: AA; AB and BB for ?-CN; A1A2 and A2A2 for ?-CN and AA; AB and BB for ?-Lg, although a direct relationship was not established with the coagulation properties or with RCT. The results of the 2 experiments show the need for studies in relation to the MCP so as to guarantee milk with adequate quality for cheese production, and also that the determination of the total protein or casein contents were not sufficient to determine these parameters. It was also possible to note that heat stress had a negative influence on MCP. For the cheese industry, a long RCT is the result of a reduced coagulum formation velocity with a weak final consistency, which can result in losses in yield and in overall quality, principally for matured cheeses. Keywords: Milk coagulation. Coagulation time. Rheology.Cheeses

Effect of THI on milk coagulation properties of Holstein-Friesian dairy cattle

ABSTRACT The objective of this study was to evaluate the effect of temperature-humidity index (THI) on the milk coagulation properties of Holstein-Friesian dairy cattle from northeast part of Italy. A total of 592 individual milk samples from six dairy herds were evaluated. The milk coagulation properties traits analysed were milk rennet coagulation time and curd firmness, as well as the fat, protein, and casein contents, pH, milk aptitude to coagulate (IAC), and the somatic cell count. The THI was determined during the periods of sample collection. The THI results showed that values of up to 75 did not significantly change the IAC values; however, when the THI values were above 75, the IAC decreased significantly. The control of THI can be used to guarantee appropriate milk coagulation properties

milk coagulation properties and methods of detection

ABSTRACT: One of the most crucial steps in cheesemaking is the coagulation process, and knowledge of the parameters involved in the clotting process plays an important technological role in the dairy industry. Milk of different ruminant species vary in terms of their coagulation capacities because they are influenced by the milk composition and mainly by the milk protein genetic variants. The milk coagulation capacity can be measured by means of mechanical and/or optical devices, such as Lactodynamographic Analysis and Near-Infrared and Mid-Infrared Spectroscopy

DESENVOLVIMENTO E CARACTERIZAÇÃO DE QUEIJO ANÁLOGO AO BOURSIN

O presente trabalho teve como objetivo a elaboração de queijos análogos ao Boursin. Foram desenvolvidas duas formulações de queijo, a primeira elaborada com leite de vaca (queijo A) e a segunda com a mistura de leite de cabra e de vaca (queijo B). Os produtos foram caracterizados quanto à composição centesimal, qualidade microbiológica e aceitação sensorial. As formulações foram classificadas como queijos de muita alta umidade, sendo o queijo “A” como gordo e o “B” como semi-gordo. Ambas as formulações apresentaram conteúdo de gordura, inferior ao queijo Boursin tradicional. O queijo B evidenciou maiores teores de proteína, umidade e conteúdo mineral. Ambas as formulações obtiveram boa aceitação sensorial e o teste de intenção de compra revelou que 76 % dos julgadores comprariam o queijo formulado com leite de vaca e que 78 % comprariam o queijo formulado com a mistura dos leites caprino e bovino. A elaboração de queijos análogos ao Boursin a partir da mistura de leite de cabra e de vaca, bem como somente com leite bovino pode representar opção para diversificação da produção de queijos em laticínios de pequeno porte em razão da simplicidade técnica e do elevado valor agregado do produto

Seasonal Effect on Milk Composition, Somatic Cell Content and Milk Coagulation Properties of Italian Holstein-Friesian Cows

This study investigated the seasonal effect on composition, somatic cell content and coagulation properties of bovine milk during two different periods of the year (summer and autumn). 592 samples of raw milk from Italian Holstein-Friesian cows from different locations in the Veneto region, Italy, were collected. The samples were submitted to the following analyses: fat, protein, casein and lactose percentages and pH by infrared spectroscopy; somatic cell counting by optical fluorescence and milk coagulation properties expressed in rennet coagulation time (RCT, min) and curd firmness or consistency 30 minutes after the addition of rennet (a30, mm) by lactodinamography. The index of the aptitude of milk to coagulate (IAC) was also determined from the lactodinamographic parameters that were obtained. To verify the environmental conditions, the temperature humidity index (THI) was calculated for each collection period. No significant difference (p <0.05) was observed between protein, casein, lactose and pH in the samples collected in the summer and the autumn. However, the results for somatic cells, RCT, a30 and IAC were significantly different, with lower results in the summer. Over all the total samples analysed, 41.2% showed a milk that did not coagulate in the 30 minutes, with a higher percentage for samples collected in the summer and during this period presented lower results to of RCT, a30 and IAC; the THI values, as expected, were higher in the summer than in the autumn. The THI presented statistically different means (p <0.05), which were 73.24 in the summer and 57.43 in the autumn. Milk with this characteristic is not suitable for cheese production; however, it is suitable to produce fluid milk, or for other derivatives where enzymatic coagulation is not part of the process

Evaluation of enzymatic coagulation of milk from a herd of Holstein cows in three periods of the year / Avaliação enzimática da coagulação do leite de um rebanho de vacas Holandesas em três períodos do ano

The milk coagulation capacity of fourteen Holstein cows was analyzed in three different periods of the year, using a low amplitude dynamic oscillatory rheological analysis. In most of the samples analyzed, the modules G' and G" increased with the time of coagulation and the gels were characterized as weak. However, the rheological results in real time of the coagulation showed that the milks of two animals, one for presenting slow coagulation (greater than 36 minutes) and the other for not coagulating are unsuitable for cheese production by enzymatic coagulation. The values of the Temperature and Humidity Index were less than 72 and did not influence the rheological properties. Significant differences between fat and lactose contents and between pH and somatic cell score values were found between the analysis periods. Evaluating the milk coagulation capacity and the strength of the gel formed are essential to assess the appropriate destination of milk, that is, milk for cheese production or milk for the production of derivatives that do not depend on enzymatic coagulation

Milk coagulation properties and methods of detection

ABSTRACT: One of the most crucial steps in cheesemaking is the coagulation process, and knowledge of the parameters involved in the clotting process plays an important technological role in the dairy industry. Milk of different ruminant species vary in terms of their coagulation capacities because they are influenced by the milk composition and mainly by the milk protein genetic variants. The milk coagulation capacity can be measured by means of mechanical and/or optical devices, such as Lactodynamographic Analysis and Near-Infrared and Mid-Infrared Spectroscopy

Effect of THI on milk coagulation properties of Holstein-Friesian dairy cattle

ABSTRACT The objective of this study was to evaluate the effect of temperature-humidity index (THI) on the milk coagulation properties of Holstein-Friesian dairy cattle from northeast part of Italy. A total of 592 individual milk samples from six dairy herds were evaluated. The milk coagulation properties traits analysed were milk rennet coagulation time and curd firmness, as well as the fat, protein, and casein contents, pH, milk aptitude to coagulate (IAC), and the somatic cell count. The THI was determined during the periods of sample collection. The THI results showed that values of up to 75 did not significantly change the IAC values; however, when the THI values were above 75, the IAC decreased significantly. The control of THI can be used to guarantee appropriate milk coagulation properties

DESENVOLVIMENTO E CARACTERIZAÇÃO DE QUEIJO ANÁLOGO AO BOURSIN

O presente trabalho teve como objetivo a elaboração de queijos análogos ao Boursin. Foram desenvolvidas duas formulações de queijo, a primeira elaborada com leite de vaca (queijo A) e a segunda com a mistura de leite de cabra e de vaca (queijo B). Os produtos foram caracterizados quanto à composição centesimal, qualidade microbiológica e aceitação sensorial. As formulações foram classificadas como queijos de muita alta umidade, sendo o queijo “A” como gordo e o “B” como semi-gordo. Ambas as formulações apresentaram conteúdo de gordura, inferior ao queijo Boursin tradicional. O queijo B evidenciou maiores teores de proteína, umidade e conteúdo mineral. Ambas as formulações obtiveram boa aceitação sensorial e o teste de intenção de compra revelou que 76% dos julgadores comprariam o queijo formulado com leite de vaca e que 78% comprariam o queijo formulado com a mistura dos leites caprino e bovino. A elaboração de queijos análogos ao Boursin a partir da mistura de leite de cabra e de vaca, bem como somente com leite bovino pode representar opção para diversificação da produção de queijos em laticínios de pequeno porte em razão da simplicidade técnica e do elevado valor agregado do produto