Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Protein – amino acid – or yeast containing
Reexamination Certificate
2001-10-01
2004-07-27
Bhat, N. (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Protein, amino acid, or yeast containing
C426S520000, C426S583000, C426S657000, C530S833000
Reexamination Certificate
active
06767575
ABSTRACT:
The invention relates to a process for producing a concentrate of denatured whey protein aggregates, preferably having a mean aggregate size (median) in the range from 1 to 4 &mgr;m, and to a stable foam product obtainable by this process.
Proteins in foods frequently do not exist as soluble individual molecules, but in the form of relatively large aggregates or particles. Such particulate structures can exist naturally, as is the case with casein micelles in milk or may not be formed until during the production process, for instance in the production of ricotta by coagulating the whey proteins [KALAB, M. (1990) “Microparticulate protein in foods”, Journal of the American College of Nutrition, 9, 374-387]. The mouthfeel caused by such aggregates or particles is essentially influenced by their size. Particles which are smaller than 0.1 &mgr;m are not perceived, so that a watery-empty impression results [LÜTH, A. (1991): Frettreduktion mit Hilfe mikropartikulierter Proteine—ein neues Konzept zur Entwicklung von “Light-Produkten” [Fat reduction using microparticulate proteins—a novel concept for developing “light products” , DMZ-Lebensmittelindustrie und Milchwirtschaft, 112, 762-766].
Protein aggregates which are in the size range of emulsified fat droplets, that is to say between 0.1 and 10 &mgr;m, can cause a creamy-smooth mouthfeel [MILLER, M. S. (1994) “Proteins as fat substitutes” In: Protein Functionality in Food Systems (Editors: HETTIARACHCHY, N. S.; ZIEGLER, G. R.), New York, Basle, Hong Kong].
Larger particles are detected in the mouth individually and are perceived as floury to sandy. However, it is not possible to define an exact limit of particle size at which roughness occurs, since subjective factors also play a role. Cited data extend from 3 to 40 &mgr;m. Other properties of the particles, such as shape, deformability and surface structure, also play a role, as do the properties of the surrounding environment, in particular its viscosity (MILLER, op. cit.).
FR-A 1 453 815 discloses a process for recovering the proteins remaining in the whey after coagulating milk, in which the whey is first adjusted to a pH between 4.6 and 7.0, in the case of the example to a pH of 4.65, and is then heated to a temperature between 70° C. and 100° C. in the case of the example 90° C., in order to precipitate out the proteins. The precipitated proteins are then removed by a centrifugation. Generally no information is provided on the size of the resultant protein aggregates in this publication. At the pH of 4.65 used in the case of the example, the proportion of protein aggregates in the desired order of size to achieve a creamy-smooth mouthfeel is low, however, and the yield of the process is therefore poor in this respect.
VISSER and BAKKER (EP-A 0 347 237) describe a process in which whey proteins are heated at low starting concentrations at temperatures below 100° C., in particular between 65° C. and 75° C. Within this temperature range the heating time is set so that no more than 10% of the proteins are denatured, that is to say become insoluble at a pH of 4.6. The denatured proteins are then concentrated, so as to give a dispersion of non-aggregated macrocolloidal particles having diameters of 0.1 to 10 &mgr;m.
Under similar heating conditions (60° C. to 80° C.), according to HAKAART et al. (EP-A 0 412 590) a food composition having an elevated content of &agr;-lactalbumin can be produced from whey having a protein content of less than 8% or from an &agr;-lactalbumin-enriched fraction, with simultaneous application of a low amount of shear. The non-aggregated microcolloidal particles which are obtained in this process have a mean particle size in the range from 0.1 to 10 &mgr;m.
WO-A 92/20239 [ASHER et al.] describes a process for producing a fat substitute for use in ice cream manufacture, in which, via ultrafiltering whey, a whey concentrate (WPC) is obtained and by subsequent short-time heating of the resultant whey concentrate to between 75° C. and 85° C., the whey proteins are partially denatured. This treatment leads to a product of coagulated particles of a size which is not defined in more detail. If the denaturation conditions are intensified in order to obtain a higher degree of denaturation, in the case of this known process a product is obtained having larger particles which can readily be differentiated, which makes it completely unsuitable for use in ice cream manufacture.
A subsequent mechanical treatment of heat-denatured whey proteins, in particular high shear, can also lead to aggregate sizes in the micrometer range: in a process developed by PAQUIN et al., [PAQUIN, P.; LEBEUF, Y.; RICHARD, J. P.; KALAB, M. “Microparticulation of milk proteins by high pressure homogenization to produce a fat substitute” in: IDF Special Issue 9303: Protein & Fat Globule Modifications 389-396 (1993], ultrafiltered and diafiltered whey is first heated in the neutral or acidic pH range at 95° C. for 5 min. This gives a roughly 90% denaturation and aggregation of the whey proteins. The heated concentrate is then homogenized in a special high-pressure homogenizer, called a microfluidizer, at a pressure of 750 bar. The coarsely aggregated structure is broken down by this treatment into small spherical particles of about 1 to 10 &mgr;m in diameter.
Comparable particle sizes were found by SPIEGEL, T. KESSLER, H. G. [“Continuous formation of gel structures and stable foams based on a heat treated and acidulated whey protein concentrate” in Texture of Fermented Milk Products and Dairy Desserts, Proceedings of the IDF Symposium in Vicenza, 106-114, (1998)], when a whey concentrate containing 10% protein and 13% lactose was heated at 80° C. and, during the subsequent cooling, was subjected to intensive shear treatment in a scraped-surface heat exchanger.
These known processes share the fact that the yield of protein aggregates in the desired size of about 0.1 to 10 &mgr;m is low. Furthermore, these processes are for the most part complicated and expensive and therefore not of interest for industrial application.
The object of the invention is therefore to provide a process for producing denatured whey protein aggregates, preferably having a size of essentially 0.1 &mgr;m to 10 &mgr;m [mean aggregate size (median) in the range from 1 to 4 &mgr;m] which is simple to carry out and is able to provide the desired protein aggregates reliably and in high yield.
This object is achieved by a process for producing a concentrate of denatured whey protein aggregates, preferably having a mean aggregate size (median) in the range from 1 to 4 &mgr;m, which comprises the steps that
a) an aqueous solution containing whey proteins enriched to a protein content of at most 4% by weight is heat-denatured to ≦80%, based on the proteins, by hot-holding at a temperature in the range from 75 to 150° C. at a pH in the range from 5.0 to 7.0 under essentially non-shearing conditions, and that
b) a concentration step is then carried out, preferably to a concentration of the denatured whey proteins between 5 and 20%.
The expression used above, that the mean aggregate size (median) is between 1 and 4 &mgr;m, means that, essentially, the aggregate size is to be between 0.1 and 10 &mgr;m; in this case the median is defined such that at a given particle size distribution, 50% by volume of the particles are below this value and 50% by volume are above it. This median is also abbreviated in specialist circles to D
50.3
. If the aggregate size is to be “essentially” between 0.1 and 10 &mgr;m, this is to be taken to mean the fact that more than 90% by volume, preferably more than 95% by volume, of the aggregates are in said particle size range between 0.1 to 10 &mgr;m.
The inventive production process requires no shearing action, or only slight shearing action, so that complex apparatuses are not required.
An essential feature of the inventive process is that a controlled denaturation is carried out using the starting raw material in the inventivel
Huss Manfred
Spiegel Thomas
Bhat N.
Ostrolenk Faber Gerb & Soffen, LLP
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