Food or edible material: processes – compositions – and products – Fermentation processes – Of milk or milk product
Reexamination Certificate
2001-05-23
2004-06-22
Wong, Leslie (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of milk or milk product
C426S034000, C426S042000, C426S580000, C426S583000
Reexamination Certificate
active
06753022
ABSTRACT:
AREA OF THE INVENTION
The invention relates to a method for preparing a dairy product and to a dairy product obtainable by this process.
BACKGROUND OF THE INVENTION
In the course of years more and more different types of dairy products have been developed. The consumer can choose among a wide range of products, such as custard in all kinds of flavors, ice cream, yogurt and yogurt beverages, quark (curd cheese), Biogarde®, sour cream, whipped cream and créme fraîche.
A number of the available dairy products are so-called fermented dairy products. That is to say that in the preparation of these products a fermentation step is carried out. In such a fermentation step the product is treated with microorganisms and/or enzyme systems which converts the lactose present in the product to a greater or lesser extent. Such fermentations yield, depending on the employed microorganism or mixtures of microorganisms and enzymes, a dairy product having a characteristic flavor and texture. Examples of fermented dairy products are yogurt, Biogarde®, Biomild®, quark and sour cream.
In order to give dairy products, both fermented and non-fermented, a specific desired flavor, diverse additives are added. Many employed additives are sweeteners, flavorings, aromatics and colorings. In products such as custard, fruit yogurt and yogurt beverages, it is conventional to use artificial additives, fruit juices or plant extracts.
Of a number of dairy products the consumer wishes a natural variant. By this is meant a dairy product which owes its characteristic appearance and flavor to the nature of the dairy product itself, without additives being added. Dairy products of which in particular the availability of natural variants is expected are yogurt, quark, buttermilk and the like.
U.S. Pat. No. 4,675,193 discloses a two-step method for preparing a product having a cheese flavor. To this end, in the first step a flavor developing medium having a fat content between 0.5 and 50% (w/v) and a protein content between 0.3 and 12% (w/v), for instance milk or whey, is treated with a lipase and/or protease source. This step is carried out under aerobic conditions, after which the employed lipase and/or protease source is deactivated. In a second step a fermentation with a lactic acid producing microorganism is carried out.
As the lipase and/or protease source, non-pathogenic microorganisms are preferably used, such as
Penicillium roqueforti, Oidum lactis
(
Geotrichum candidum
),
Cladisporum butaryl,
Micrococcus and
Candida lipsolytica.
Preferably,
C. lipsolytica
is used.
The treatment step in which the flavor developing medium is used comprises a fermentation in which the lipase and/or protease source acidifies the medium to a pH between 4.5 and 5.5, followed by a deactivation.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a dairy product which as regards texture corresponds to a known dairy product, such as yogurt or quark, but which has a different flavor and/or odor.
Surprisingly, it has been found that such dairy products can be prepared by bringing a specific aroma into the dairy product, which aroma is produced by a specific aerobic microorganism which is kept under anaerobic conditions for some time. Preferably, a conventional fermentation is carried out during this anaerobic period.
The invention relates to a method for preparing a dairy product in which a medium comprising milk or a milk product is treated under aerobic conditions with a lactose-negative food-technologically acceptable microorganism.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
It has been found that in a medium treated under aerobic conditions with a lactose-negative, food-technologically acceptable microorganism during an anaerobic period there are formed characteristic aromas. The nature of the aroma can be adjusted by the choice of the microorganism within the class of lactose-negative, food-technologically acceptable microorganisms.
The aroma imparted according to the invention to a dairy product originates from a microorganism which hardly changes the starting material for the dairy product to be prepared in the sense that lactose is not converted. There is thus obtained a dairy product which as regards the texture is substantially equal to known variants of the dairy product prepared, but which has a completely new flavor and/or odor.
On the other hand, the use of a lactose-negative microorganism in the preparation of a dairy product is known per se. In J. Dairy Sci., (1996) 79:937-942, Kwak et al. describe a method in which a lactose-negative yeast of the species
Saccharomyces cerevisiae
is used to stabilize kefir. Kefir is a traditional, Russian, fermented milk beverage containing a minor amount of alcohol and carbon dioxide. According to Kwak et al. the lactose-negative microorganism is used to produce alcohol in a preliminary phase under anaerobic conditions. After this preliminary phase an acidification with lactic acid bacteria is carried out.
The starting material for the method according to the invention is a medium comprising milk or a milk product. It is possible to use both a non-treated milk and a milk which has been subjected previously to a heat treatment, such as a pasteurization or sterilization.
In order to prevent outgrowth of any present, contaminating microorganisms, it is preferred to start from a milk which has been previously subjected to a heat treatment.
It is also possible to use a milk-derived product having an adapted fat content, such as skim milk or cream.
In addition to the milk or the milk product, the medium can and will generally comprise nutrients for the lactose-negative, food-technologically acceptable microorganism. It is conventional to subdivide these nutrients into carbon sources and nitrogen sources. suitable carbon sources are substances which can supply the carbon required for the ripening of the lactose-negative, food-technologically acceptable microorganism, and which are compatible with the dairy product (to be prepared). Examples are glucose and potato dextrose broth (PDB). Suitable nitrogen sources are substances which can supply the nitrogen required for the ripening of the lactose-negative, food-technologically acceptable microorganism and have no negative effect on the dairy product (to be prepared). Examples are malt extract, yeast extract and tryptone.
The choice of the nutrients to be used will depend on the nature of the lactose-negative, food-technologically acceptable microorganism. When the lactose-negative, food-technologically acceptable microorganism is a yeast, glucose, PDB and tryptone are preferably used as nutrients. When the lactose-negative, food-technologically acceptable microorganism is a bacterium, glucose and/or tryptone are preferably used as nutrients.
The amounts of the nutrients in the medium which form the starting material for a method according to the invention are adjusted to the nature of the lactose-negative, food-technologically acceptable microorganism. The total amount of added nutrients required for the aroma-forming microorganism should be sufficient to grow the microorganism, but not so large as to bring about an undesired aroma or an aroma of an undesired intensity. When the carbon source is PDB, in the case that the lactose-negative, food-technologically acceptable microorganism is a yeast, the amount thereof will range between 1 and 3 g. When in the same case tryptone is the nitrogen source, 0.2 to 1 g thereof will be used. When the carbon source is glucose, in the case that the lactose-negative, food-technologically acceptable microorganism is a bacterium, the amount thereof will range between 0.5 and 5 g. When in the same case tryptone is the nitrogen source, 0.2 to 1 g thereof will be used. All this can be simply established by those skilled in the art by way of experiment.
The microorganism with which the medium according to the invention is treated is a lactose-negative, food-technologically acceptable microorganism. By this is meant a microorganism which is not capable of converting lactose. In other w
Spinnler Henry-Eric
Vermin Reinier Johannes C.
Campina Melkunie B.V.
Leydig , Voit & Mayer, Ltd.
Wong Leslie
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