Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Gels or gelable composition
Patent
1992-12-07
1994-10-25
Pratt, Helen
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Gels or gelable composition
426580, 426582, 426583, 426656, 426657, A23L 10562
Patent
active
053587308
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for instantaneous coagulation or gelling, in the absence of a coagulating agent, at a pH higher than its isoelectric pH, of a protein coagulable at the said isoelectric pH.
The invention also relates to a coagulum or gel which can be obtained by the said process and to the use of such a coagulum or gel in the preparation of a foodstuff.
The process of the invention is applicable, in particular, to milk caseins and to analogous proteins.
In the description which follows reference will most often be made, with the aim of simplification, to the coagulation of milk or of dairy products, but it must be understood that this reference to dairy products must not be regarded as limiting.
The coagulation of milk results from physico-chemical changes which take place at the level of the casein micelles. The two types of coagulation known to date and widely used in dairy and cheese technology are induced either by the action of coagulant enzymes, such as, for example, rennet, or by acidification to the isoelectric pH of the caseins, and produce a coagulum which is also termed "curd" and a liquid residue known as whey.
The action of rennet is reflected in attack on kappa-casein, which is cut at the level of the 105 and 106 residues, and gives rise to changes in the micelle: the net charge is reduced and the surface of the micelle becomes more hydrophobic. These changes modify the equilibria between the attractive and repellent forces between the micelles and, when the degree of hydrolysis of the kappa-casein is sufficient, coagulation, and the formation of a network of para-casein micelles, takes place.
The acidification of milk is also reflected in a coagulation, by a similar process (fall in the absolute value of the zeta potential) when the isoelectric pH of casein is reached, but the micelles are not preserved: in fact, colloidal calcium phosphate, which stabilized the micelles, is dissolved by the acidification. The lactic curds are therefore substantially decalcified, the minerals being entrained with the serum.
It is also known that caseins, in their natural environment, are remarkably stable to heat treatments: in fact, milk must be treated under pressure at temperatures of the order of 130.degree. C. for 10 to 15 minutes, or at 115.degree. C. for 50 minutes, in order for flocculation to be observed; see, for example, C. ALAIS, Science du lait, 4th edition, Editions SEPAIC, Paris, page 163.
The whey proteins are more sensitive to heat. For example, beta-lactoglobulin has a denaturing temperature of the order of 80.degree. C. However, in milk, it does not precipitate at this temperature but bonds to the kappa-casein. In fact, it is difficult to obtain gels by coagulation of the whey proteins when the concentration of these proteins is less than 5% while their concentration in milk is of the order of 0.6%.
Moreover, the production technologies for cheeses or dairy products also use another starting material derived from milk: the retentate resulting from concentration of the milk by ultrafiltration. This process enables water to be removed, as well as soluble compounds such as lactose, inorganic salts or small peptides (without, however, significantly changing the concentration thereof), whereas the more bulky compounds (fat globules, proteins) do not pass through the membrane and are therefore concentrated in the retentate.
The use of retentates in cheese technology has been the subject of numerous scientific publications and patents, one of the earliest of which is French Patent 2 052 121, which describes the process known under the name MMV process.
In cheese technologies based on ultrafiltration retentate, it is sometimes desired to lower the relative proportion of lactose. This lowering may be effected by an operation known as diafiltration, which consists in adding, before, during or at the end of ultrafiltration, a known volume of water and in prolonging the ultrafiltration operation so as to remove an amount of permeate equivalent to the amount of water added. Fo
REFERENCES:
patent: 5217741 (1993-06-01), Kawachi et al.
Sagara, "Preparation of Cheese Curd", Patent Abstracts of Japan, vol. 12, No. 338 (C-527), Sep. 1988.
Raynes et al, "Sensory and curd characteristics of cottage cheese manufactured from 16% total solid retentate", Journal of Dairy Science, vol. 71, Suppl. 1, 1988, p. 81, Abstract No. D59.
Maubois et al, "Making Ricotta cheese by ultrafiltration", Journal of Dairy Science, vol. 61, No. 7 Jul. 1978, pp. 881-884.
Audidier Yves
Dame-Cahagne Michele
Frouin Andre
Mouret Pascale
Bongrain S.A.
Pratt Helen
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