The Effect of Heating on Physicochemical and Renneting Properties of Milk: A Comparison between Caprine, Ovine and Bovine Milk

Effects of high pressure treatment on the rennet coagulation and cheese-making properties of heated milk

“…The inhibitory effect of such heat treatment on the rennet coagulation properties of milk (Table 1) is in agreement with results of previous studies (Dalgleish, 1990;Lucey et al, 1993;Park et al, 1996;Raynal & Remeuf, 1998;Singh, Shalabi, Fox, Flynn, & Barry, 1988;Waugana et al, 1996Waugana et al, , 1998. Although heat treatment of milk has some effect on the primary stage of rennet coagulation, i.e., the hydrolysis of n-casein by chymosin, heat-induced inhibition of rennet coagulation is primarily due to effects on the secondary stage of rennet coagulation, i.e., the aggregation of the para-casein micelles (Van Hooijkdonk, De Koster, & Boertiger, 1987;Vasbinder et al, 2003).…”

“…In milk heated for 10 min at 90 -C, a high proportion of the whey proteins is already denatured (Anema & Li, 2003;Raynal & Remeuf, 1998); thus, the disruptive effect of pressure on the casein micelles is the principal mechanism through which HP influences RCT, which explains the reductions in the RCT of heated milk with increasing pressure. The decrease in the RCT of heated milk with increasing pressure up to 400 MPa, followed by little further effect at higher pressures, is in agreement with decreases in casein micelle size (Gaucheron et al, 1997;Needs et al, 2000;Huppertz et al, 2004a;Huppertz, Fox, & Kelly, 2004c) or light scattering properties (Desobry-Banon et al, 1994;Gaucheron et al, 1997;Huppertz et al, 2004c;Johnston, Austin, & Murphy, 1992) at up to 400 MPa, with little further effect at higher pressures.…”

“…However, for the manufacture of semi-hard and hard cheeses, heat treatment adversely affects other cheesemaking properties of milk, i.e., it significantly increases the rennet coagulation time (RCT) of milk and reduces the firmness of the rennet-induced coagulum (Lucey, Gorry, & Fox, 1993;Park, Nakamura, & Niki, 1996;Raynal & Remeuf, 1998;Vasbinder, Rollema, & De Kruif, 2003;Waugana, Singh, & Bennett, 1996. Furthermore, cheese from heated milk has an excessively high moisture content (Imafidon & Farkye, 1994Pearse, Linklater, Holl, & MacKinlay, 1985;Rynne, Beresford, Kelly, & Guinee, 2004) due to association of whey proteins at the casein micelle surface, which impedes the fusion of the para-casein network (Singh & Waugana, 2001;Vasbinder et al, 2003;Walstra, Van Dijk, & Geurts, 1985).…”

Seasonal changes of the chemical composition of cheese obtained from the milk of indigenous Polish breeds of sheep

“…According to Raynal and Remeuf (1998), a higher casein content in ewe milk favours micelle-micelle interactions, leading to more rapid aggregation of the particles during coagulation. The content of milk components (mainly fat and protein) and also other factors such as casein micelle diameter and mineral equilibrium, which also change during lactation, can affect curd firmness (Remeuf et al, 1991;Pellegrini et al, 1997).…”

Atividade proteolítica de bactérias psicrotróficas em leites estocados em diferentes temperaturas

“…As proteinases produzidas por essa microbiota são termoestáveis, mantêm-se íntegras e ativas após o tratamento térmico, e os prejuízos econômicos decorrentes dessa atividade são consideráveis (Rowe et al, 2003). A clivagem e a consequente floculação das micelas de caseína geram, além da geleificação do leite UHT (Renner, 1998;Datta & Deeth, 2001), dificuldades para a obtenção dos parâmetros físico-químicos necessários na fabricação de queijos (Raynal & Remeuf, 1998). Além disso, o acúmulo de dipeptídeos e de aminoácidos (especialmente tirosina) confere ao leite o sabor amargo (Chen et al, 2003).…”