AND DAIRY PRODUCTS

FIELD OF THE INVENTION

[001] This invention is directed to the antioxidative and antimicrobiological preservatives of milk and dairy products and a method of using the same. The preservatives are extracts of plants of the labiatae family and mixtures. The labiatae family includes, inter alia, rosemary, sage, lemon balm, oregano, savory, mint and thyme.

BACKGROUND OF THE INVENTION

[002] Milk and milk products are known to be easily contaminated by bacteria and generally, have a relatively short shelf-life. Further, the oxidation of milk fats causes milk and dairy products to have an unpleasant smell and taste. Other than lipolysis, which causes hydrolytic rancidity, milk fat oxidation is one of the main factors influencing the shelf-life of milk and dairy products. The appearance of smell and taste of oxidation is mostly felt in milk, cream and butter, as these products have a milder smell and taste.

[003] Apart from oxidation, milk and dairy products are strongly subject to microbial decay. The milk industry controls oxidation and microbial decay of milk and dairy products by using low storage temperature, oxygen presence control, heat treatment, adequate packaging and the addition of synthetic preservatives and antibiotics to the milk and dairy products.

[004] Sythetic preservatives and antibiotics have been used for decades in the preservation of products against microbial spoilage. Recently, the use of naturally occurring substances, such as extracts from plant and animal materials, has become more common in the protection against the microorganisms responsible for food spoilage and pathogenic bacteria. This is mainly since synthetic preservatives tend to exert undesired side effects on human health.

[005] Therefore, there is a need to lengthen the shelf-life of milk and milk-products by using naturally occurring substances.

SUMMARY OF THE INVENTION

[006] This invention is directed to a preservative for milk and dairy products comprising an extract from a plant of the labiatae family or a mixture of two or more extracts of plants of the labiatae family BRIEF DESCRIPTION OF THE DRAWINGS

[007] Figure 1 shows the results of a Rancimat test of three samples of butter to which three different preservatives were added in comparison to a control butter sample to which no preservatives were added;

[008] Figure 2 shows the results of an acid value test of three samples of cream to which three different preservatives were added in comparison to a control cream sample to which no preservatives were added;

[009] Figure 3 shows the results of a TBA test of three samples of a whey concentrate to which three different preservatives were added in comparison to a control whey concentrate sample to which no preservatives were added; and

[0010] Figure 4 shows the results of a TBA test of one sample of milk powder to which a natural preservative was added in comparison to a control sample to which no preservative was added.

[0011] Figure 5 shows the results of an acid value test of one sample of milk powder to which a natural preservative was added in comparison to a control sample to which no preservative was added.

DETAILED DESCRIPTION OF THE INVENTION

[0012] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

[0013] This invention is directed to a method for the antioxidative and antimicrobiological preservation of milk and dairy products comprising adding natural preservatives prepared from extracts of plants of the labiatae family or mixtures thereof to the milk or dairy products. The labiatae family includes, inter alia, rosemary, sage, lemon balm, oregano, savory, mint and thyme.

[0014] The major active substances in the extracts from plants of the labiatae family are carnosic acid, rosmarinic acid, and derivatives thereof. Carnosic acid is an oil-soluble active substance, while rosmarinic acid is a water-soluble active substance. [0015] The oil-soluble extract from plants of the labiatae family contains up to 100 % by weight of carnosic acid. The water-soluble extract from plants of the labiatae family contains up to 100 % by weight of rosmarinic acid. According to this invention, the natural preservative prepared and added to the milk or dairy products comprises either one of or a mixture of the oil-soluble and the water soluble extracts.

[0016] According to certain embodiments of the invention, the extracts from plants of the labiatae family and their mixtures are combined with any appropriate additive or carrier. When the additive or carrier dilutes the extract, it allows the extract to be better distributed in the product that is to be preserved and eases the handling thereof. Such additives include propylene glycol, maltodextrin, sugar, edible oil, edible salt and any other additives approved for consumption, as well as mixtures thereof. According to further embodiments, an emulsifier approved for consumption is added to the extract. According to further embodiments, an antioxidant approved for consumption is added to the extract.

[0017] According to further embodiments, additional plant extracts that have antioxidative and/or antimicrobial activity are added to the milk and/or dairy products. According to some embodiments, the additional plant extracts are selected from green tea extract, citrus extracts, citrus extracts based on naringin, olive extract, hops extract, carrot extract, guarana extract, grape seed extract, pomegranate extract and mixtures thereof. The various extracts, additives and carriers may be added to the milk or dairy products in a single solution or in several separate solutions, simultaneously or separately.

[0018] According to this invention, at least one of the additives, carriers or the additional active ingredients may have a synergistic effect with the labiatae extract. A combination of the extract of labiatae with synergists contributes to an improved synergistic antioxidative and antimicrobial protection of the product.

[0019] According to this invention, the labiatae extracts as well as their mixtures are used in concentrations varying for each type of milk product so that they do not alter the organoleptic characteristics thereof. Further, thermal treatment (e.g., pasteurization) of the milk or dairy product does not affect their activity.

[0020] According to certain embodiments, the total concentration of the active ingredients (i.e., mainly the sum of the carnosic acid and the rosmarinic acid), added to the milk or dairy product is about 1.0-1000 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 1.0-50 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 1.0-10 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 10-20 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 20-30 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 30-40 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 40-50 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 50-60 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 60-70 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 70-80 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 80-90 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 90-100 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 100-200 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 200-300 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 300-400 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 400-500 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 500-600 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 600-700 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 700-800 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 800-900 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 900-1000 mg/kg. According to another embodiemnt, the total concentration of the active ingredients is above about 1.0 mg/kg. According to another embodiemnt, the total concentration of the active ingredients is less than about 1000 mg/kg. According to another embodiemnt, the total concentration of the active ingredients is less than about 100 mg/kg. According to further embodiments, the total concentration of the active ingredients is about 40mg/kg. According to further embodiments, the total concentration of the active ingredients is about 20 mg/kg.

[0021] According to certain embodiments, the natural preservative of this invention is added directly to the milk and/or dairy products. According to further embodiments, the natural preservative of this invention is added to the milk, prior to the production of the dairy product therefrom. [0022] Various aspects of the invention are described in greater detail in the following Examples, which represent embodiments of this invention, and are by no means to be interpreted as limiting the scope of this invention.

EXAMPLES

[0023] The rosemary extract used in the following examples was prepared conventionally, i.e., by extracting rosemary with acetone, filtering and evaporating the solvent. Further, in all of the following examples, where a rosemary extract mixture was added to the sample, the mixture comprised about 10% rosemary extract (to yield 4% camosic acid), about 10% delta tocopherol, about 5% gamma tocopherol, about 0.8% alpha tocopherol, about 0.1% beta tocopherol, about 20% DATEM and rapeseed oil as a carrier to complete to 100%.

EXAMPLE 1

[0024] The following butter samples were prepared:

^■ Butter Sample 1 (0.1% rosemary extract sample): a rosemary extract, in a concentration of 0.1 wt. % (corresponding to 40 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid), was added to butter melted over a water bath at a temperature of 40°C;

^■ Butter Sample 2 (0.05% Mixture Sample): A mixture of a rosemary extract with tocopherols and the DATEM emulsifier in a concentration of 0.05 wt.% (corresponding to 20 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid) was added to butter melted over a water bath at a temperature of 40°C;

■ Butter Sample 3 (0.1% Mixture Sample): A mixture of a rosemary extract with tocopherols and the DATEM emulsifier in a concentration of 0.1 wt.% (corresponding to 40 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid) was added to butter melted over a water bath at a temperature of 40°C;

■ Butter Control: a control sample of butter without any additives was also prepared.

[0025] In order to asses the oxidative stability of the butter samples, the Rancimat test was performed at 100°C on three grams of each of the samples. The Rancimat test is used to conductometrically measure the obtained products of oxidation of unsaturated fatty acids. The result is given as induction time, i.e. the time in which the peroxide number achieves the value of 100 micro eq/kg of fat. In order to perform the Rancimat test, the cell was heated to 100°C and the samples were aerated in order to promote oxidation.

[0026] As shown in Figure 1, the 0.1 wt.% rosemary extract butter sample had, approximately, a five-times longer induction time, i.e., a five times better oxidative stability, in comparison to the control sample. Further, the 0.05% Mixture Sample had, approximately, a nine times longer induction time in comparison to the control sample and the 0.1% Mixture Sample had, approximately, an 11 times longer induction time in comparison to the control sample.

EXAMPLE 2

[0027] The following cream samples were prepared:

^■ Cream Sample 1 (0.1% rosemary extract sample): a rosemary extract, in a concentration of 0.1 wt. % (corresponding to 40 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid), was stirred into cream comprising 40% fat. The cream was stored in a refrigerator at a temperature of 4°C for 15 days.

^■ Cream Sample 2 (0.05% Mixture Sample): A mixture of a rosemary extract with tocopherols and the DATEM emulsifier in a concentration of 0.05 wt.% (corresponding to 20 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid) was stirred into cream comprising 40% fat. The cream was stored in a refrigerator at a temperature of 4°C for 15 days;

^■ Cream Sample 3 (0.1% Mixture Sample): A mixture of a rosemary extract with tocopherols and the DATEM emulsifier in a concentration of 0.1 wt.% (corresponding to 40 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid) was stirred into cream comprising 40% fat. The cream was stored in a refrigerator at a temperature of 4°C for 15 days;

^■ Cream Control: a control sample of cream comprising 40% fat without any additives was also kept in a refrigerator at a temperature of 4°C for 15 days.

[0028] In order to asses the degradation of each cream sample, the acid value of each sample was assessed on day 15 according to the following procedure:

The acid value is defined according to the mass of KOH in milligrams that is required to neutralize the free fatty acids contained in lg of oil or fat. Accordingly, lOg of the tested sample were placed in an Erlenmeyer. 50ml of the mixture of the solvents ethanol and diethyleter, in a volume ratio 1 :1, were added into the Erlenmeyer, and the mixture was shaken well. Three drops of a phenolphthalein solution were added to the solution in the Erlenmeyer. The solution was then titrated with a 0.1M solution of potassium hydroxide until the colour switched from colourless to pink. The acid value (AV) was calculated by the following formula:

AV=(10*b*f*0.561)/a

wherein: AV- acid value (mg of KOH / g of fat) a- weighed sample (g)

b- amount (in ml) of potassium hydroxide used for the titration

f- a factor relating to the molar concentration of the potassium hydroxide, in this example equalling 0.1

0.561 factor referring to molar mass of potassium hydroxide (56.1) and to 1 g of fat, if the titration is performed with 0.1 M solution of potassium hydroxide

[0029] As shown in Figure 2, the 0.1% rosemary extract sample had a 30% lower acid value than the control, corresponding to a 30% higher oxidative stability. Further, the 0.05% Mixture Sample had a 56% lower acid value than the control and the 0.1% Mixture Sample had a 57% lower acid value than the control.

EXAMPLE 3

[0030] They following whey samples were prepared:

[0031] Whey Sample 1 (0.1% rosemary extract sample): a rosemary extract, in a concentration of 0.1 wt. % (corresponding to 40 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid), was stirred into a whey concentrate comprising 0.3% fat. The whey concentrate was stored in a refrigerator at a temperature of 4°C for three weeks.

Whey Sample 2 (0.05% Mixture Sample): A mixture of a rosemary extract with tocopherols and the DATEM emulsifier in a concentration of 0.05 wt.% (corresponding to 20 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid) was stirred into a whey concentrate comprising 0.3% fat. The whey concentrate was stored in a refrigerator at a temperature of 4°C for three weeks;

Whey Sample 3 (0.1% Mixture Sample): A mixture of a rosemary extract with tocopherols and the DATEM emulsifier in a concentration of 0.1 wt.% (corresponding to 40 mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid) was stirred into a whey concentrate comprising 0.3% fat. The whey concentrate was stored in a refrigerator at a temperature of 4°C for three weeks;

[0032] Whey Control: a control sample of a whey concentrate comprising 0.3% fat without any additives was also kept in a refrigerator at a temperature of 4°C for three weeks.

[0033] In order to asses the degradation of the whey samples, the optical density of each sample was assessed after three weeks using the thiobarbituric acid (TB A) test. [0034] The TBA test is an empirical method for the assessment of the oxidation levels of fats and fat containing food, wherein the test results are related to the level of aldehydes present in the fats. Thiobarbituric acid specifically reacts with malonaldehyde (MDA), which yields a red chromogen, the quantity of which is determined by spectrophotometry. The result is given as the optical density measured at wavelength 532 nm. A lower optical density is a sign of a more oxidative stable product.

[0035] The TBA test was performed as follows on each of the above whey samples, including the control sample:

17.6 ml of each sample were placed in an Erlenmeyer and heated to 30 °C in water bath. 1ml of trichloroacetic acid and 2ml of 95 wt. % ethanol were added to the Erlenmeyer, which was then covered and shaken for 10 seconds. After five minutes, the contents were filtered through filter paper. 1.4 g of 2-thiobarbituric acid were diluted in 95 wt. % ethanol to a volume of 100 ml to prepare a TBA solution. 4ml of the filtrate were mixed together with 1ml of the TBA solution in a test tube. The test tube was covered, stirred and heated in a water bath at a temperature of 60°C for 60 minutes. A blank sample, for spectroscopic measurements, was prepared in the same way, only that 4 ml of distilled water were placed into the test tube instead of the filtrate. Finally, the sample was cooled and the optical density (D) was measured at 532 nm.

[0036] As shown in Figure 3, the optical density of the 0.1% rosemary extract sample was 69% lower than that of the control sample, i.e., had a 69% better oxidative stability. Further, the optical density of the 0.05% Mixture Sample was 52% lower than that of the control and the optical density of the 0.1% Mixture Sample was 70% lower than that of the control.

EXAMPLE 4

Milk powder was prepared from pasteurised milk according to the following description. Pasteurised milk with a standardized milk fat content of 3.2% was placed in two separate vessels. A mixture of rosemary extract, tocopherols and the DATEM emulsifier was added to one of the vessels in a concentration of 0.1 wt.% (corresponding to 40mg/kg of carnosol acid with traces of about 0.5% rosmarinic acid), calculated per dry matter of liquid milk.The milk in the second vessel was kept as a control sample and no additives were added thereto.

[0037] Each sample was heated to about 95°C and was then condensed in a multi-stage vaporizer. Since the vaporizer is held at a low pressure of -0.5 bar the temperature of the milk decreased during the vaporization process to about 45 - 47 °C. After condensation, the amount of the dry substances in the milk raised from 12% to about 47-48%. [0038] Then condensed milk was pumped at a high pressure of 200 bar into a drying column, which was held at a temperature of about 190 - 200 °C, where the milk was dried by dispersion, i.e., by spraying it through nozzles in a fine mist. The obtained powder was further dried in an instantizer, i.e., a fluidised bed drier, to the desired final content of humidity, which was 4%, cooled to 10-15°C and packed in suitable packaging, i.e., in a polyethylene bag placed in paper bag.

[0039] Once dried, the content of the carnosol acid in the prepared milk powder was determined using an HPLC and an electrochemical detector. The content corresponded to the value determined initially, i.e., 0.1% in the preserved powdered milk sample (and 0.0% in the control), and therefore, it was clear that the active ingredient is stable during the vaporization and drying processes detailed above.

[0040] The milk powder was kept at room temperature for 12 months and the optical density thereof was measured on a monthly basis using the TBA test. In order to perform the TBA test, the milk powder was diluted in warm water at a ratio of 12.5:87.5 (milk powder : water) and the TBA test was performed as described above in Example 3. As shown in Figure 4, the difference between the optical density of the preserved 0.1% Mixture Sample and the Control Sample, which does not comprise any preservatives, grew with time, and after a year the preserved Mixture Sample outperformed the Control Sample by a factor of 3.2, i.e., the oxidative stability thereof after a year was 3.2-times better.

[0041] In addition to the TBA test, the acid value of the Mixture Sample and the Control Sample were measured on a monthly basis, according to the procedure described in Example 2. The results of the acid value tests are presented in Figure 5 .vs. time, showing that the difference between the acid value of the preserved Mixture Sample and the Control Sample grew with time and that after a year the preserved milk powder, prepared according to this invention, (Mixture Sample) outperformed the non-preserved sample (Control Sample) by a factor of 2.4.

[0042] Further, the microbial contents of both milk powder samples were assessed after four months of storage at room temperature and the results are presented in Table I, below. Table I

[0043] As shown in Table I, the microbial content of the 0.1% Mixture Sample was consistently lower than that of the control sample (or they were both under the detection limit). Further, the total count of microorganisms in the 0.1% Mixture Sample was found to be five times lower that that of the control sample, showing that the addition of the natural preservative inhibited the growth of bacteria in the milk powder.

[0044] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.