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.

RESUMO: Uma das etapas mais importantes na fabricação de queijos é o processo de coagulação. O conhecimento dos parâmetros envolvidos nesse processo desempenha um papel tecnológico importante para a indústria de laticínios. O leite de diferentes espécies de ruminantes varia em termos de capacidade de coagulação, pois são influenciados pela composição e principalmente pelas variantes genéticas da caseína. Estas características podem ser avaliadas por meio de dispositivos mecânicos e/ou ópticos, tais como, a Análise Lactodinamográfica e a Espectroscopia de Reflectância do Visível ao Infravermelho Próximo (NIR) e Médio (MIR).

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.