Food or edible material: processes – compositions – and products – Fermentation processes – Of milk or milk product
Reexamination Certificate
2001-10-05
2004-04-06
Wong, Leslie (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of milk or milk product
C426S042000, C426S330200, C426S580000
Reexamination Certificate
active
06716461
ABSTRACT:
BACKGROUND OF THE INVENTION
1. [Technical Field of the Invention]
The present invention relates to a method for producing modified raw material milk for dairy products in which transglutaminase and a reducing agent are added to and caused to act on raw material milk for dairy products (i.e., milk as raw material for dairy products), such as raw milk or the like, whereby the milk proteins are cross-linked more effectively than before, in other words, a method for modifying milk as raw material for dairy products. By using the modified raw material milk produced according to the present invention, dairy products having improved physical properties, such as yogurt, cheese, powdered milk and the like having improved physical properties and provided with a favorable flavor and mouthfeel or texture, can be provided.
2. [Related Art]
In the production of dairy products, the value of the products depends largely on such physical properties as water-holding capacty, emulsion stability, viscosity, smoothness and the like. The manufacturers of dairy products have practiced a variety of devices to produce dairy products having further improved physical properties. For example, use of a variety of thickening polysaccharides for improving the mouthfeel and water-holding capacty of yogurt or ice cream has been widely known. Further, a variety of techniques such as use of a special lactic acid bacteria starter for reducing the separation of water from a yogurt (syneresis) (Japanese Patent Application Laid-Open No. 268874/1993), use of monoglycerides for obtaining a smooth processed cheese (Japanese Patent Application Laid-Open No. 105/1999), use of whey proteins for attaining the temperature stability of ice cream (Japanese Patent Application Laid-Open No. 135664/1997), and the like, have been reported.
Meanwhile, an attempt to improve the quality of a dairy product by using transglutaminase (Transglutaminase being abbreviated as “TG” hereinafter), which is an enzyme having the action of crosslinking proteins, has been reported. For example, it has been reported that the viscosity of a yogurt is increased by adding TG during the yogurt manufacturing process, whereby the separation of water from the yogurt (syneresis) is alleviated or reduced (Japanese Patent Application Laid-Open No. 197688/1994), that the yield of cheese curds is increased by using TG in the production process (Japanese Patent Application Laid-Open No. 173032/1996), and the like.
Such quality improvements with the use of TG have a variety of advantages from the industrial standpoint. Firstly, since even only an extremely small amount of TG is sufficient to exhibit the above effects, and at the same time, it acts directly on a food protein to exhibit the above effects, it has little adverse effect on mouthfeel. For example, when a thickening polysaccharide is added to a yogurt to improve its physical properties, even though such effects as an increase in viscosity, the prevention of separation of water from the yogurt or the like can be indeed attained, but the addition of the polysaccharide may not necessarily lead to an improvement in the overall quality of the yogurt due to the “gluey” mouthfeel of the thickening polysaccharide per se.
Secondly, in response to the customers' needs for taking in so-called “food additives” as little as possible, use of such an enzyme has a natural feel and provides a high added value to commercial dairy and the like products. Incidentally, a natural microorganism-derived TG has already been commercialized and widely used in various food processings.
The reports which have heretofore been made about the reactivity of TG to milk proteins are mainly those about the studies of whey proteins, particularly &agr;-lactoalbumin and &bgr;-lactoglobulin which are the constituents of the whey protein, or a condensed whey protein. The whey protein is known as a protein to which TG has low reactivity due to its structure in which it has S—S bonds in the molecule (Fargemand et. al., J. Agric. Food. Chem. (1997) 45, 2,514-2,519, particularly p. 2,517, lines 41 to 53). For example, Traore and Meunier have reported that when Factor XIII (TG in blood) is introduced to act on the whey protein, crosslinking polymerization does not proceed in the absence of a reducing agent (J. Agric. Food Chem. (1992) 40, 399 to 402).
Further, Aboumahmoud and Savello (J. Dairy Sci. (1990) 73, 256 to 263) have reported that when &agr;-lactoglobulin or &bgr;-lactoalbumin is crosslinked with the use of TG derived from guinea pig liver for the purpose of making a protein-based film, these whey proteins have to be preheated in the presence of a reducing agent at 85° C. for 15 minutes.
Fargemand et al. (Food Hydrocolloids, (1997) 11, 19 to 25) have made a report about the reaction between a whey protein and a calcium-independent TG and additionally reported that the TG has the effect of increasing crosslinked polymer in the presence of dithiothreitol (DTT) or cysteine and the effect of increasing the crosslinked polymer to some extent even under the alkaline conditions.
Casein, which is the main protein of milk proteins, is already known as a protein to which TG has a high reactivity (Fargemand et al., Food Hydrocolloids (1997) vol. 11, no. 3, pp. 287 to 292). For example, Nio et al. have reported the crosslinking polymerization of &agr;S
1
-casein with a TG derived from guinea pig liver (Agrc. Biol. Chem. (1986), 50, 851 to 855), and Traore et al. have reported the crosslinking polymerization of purified caseins, particularly &bgr;-casein and &kgr;-casein, with a Factor XIII
a
from human.
As compared therewith, few studies have been made on the reactivity of TG to the casein in cow milk. Only Nonaka et al. have made a report about the study in which the crosslinking polymerization and gelation of reduced skimmed milk powder with TG were compared with those of a caseinate with TG. In the report, it is stated that the casein in the reduced skimmed milk powder is inferior to the caseinate in terms of reactivity (J. Food. Sci., (1992), 57(5), 1214 to 1218).
Not a few studies have been made on the physical properties of a gel or dairy product derived from the cow milk on which TG has been acted. For example, Fargemand et al. have reported the influence of crosslinking of the casein in skimmed milk powder by TG on acidic gelation (Food Hydrocolloids (1997) vol. 11, no. 3, pp. 287 to 292), Lauber et al. have reported the crosslinking of casein by TG and the gel strength of a yogurt (Eur. Food Res. Technol., (2000), 210(5), 305 to 309), and Imm et al. have reported the gelation and water-holding capacty of the skimmed milk powder treated with TG (J. Food Sci., (2000), 65(2), 200 to 205). In addition, Lorenzen et al. have reported the properties of a yogurt made from the cow milk treated with TG, the physical properties of a whipped cream, and the formability of curd with rennet (Kiel. Milchwirtsch. Forschungsber. (1997), 49(3), 221 to 227).
As has been described above, in the crosslinking reaction of cow milk proteins with TG, attempts to decrease the required amount of TG or reaction time by improving the reactivity of TG to a milk protein, particularly a casein, are not yet been made. The reasons for this are, for example, because when evaluation was made on the function or the like of a gel, milk used as a raw material had had sufficient reactivity to observe the effects caused by the addition of TG and that the need for further improving the reactivity of a casein which is an effective substrate for TG had not been recognized, and the like.
Meanwhile, a reducing agent such as glutathione or the like is used in an enzyme reaction for the purpose of stabilizing an enzyme or improving reactivity to the enzyme. As described above, an example thereof is to improve the reactivity of a whey protein by treating the whey protein with a reducing agent such as DTT to reduce S—S bonds.
As an example of improving the gel properties of food by using a reducing agent together with TG when TG was used on a food protein other t
Kumazawa Yoshiyuki
Miwa Noriko
Nakagoshi Hiroyuki
Sakaguchi Shoji
Ajinomoto Co. Inc.
Wong Leslie
LandOfFree
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