Process for producing milk and milk-related products with extended shelf life

Abstract

Disclosed is process for producing milk and milk-related products with extended shelf life. The process comprises the steps of separating whole milk is a cream fraction and a skimmed milk fraction, wherein the skimmed milk fraction has a fat content of 0.5% by weight or less, subjecting the skimmed milk fraction to a heat treatment, said heat treatment comprising heating the skimmed milk fraction to 152? C. to 165? C. for 500 ms or less, and cooling of the skimmed milk fraction to a temperature at or below 70? C. The produced milk and milk-related products maintains a high degree of undenatured whey protein despite the high treatment temperature.

Claims

1. A process for producing a skimmed milk fraction comprising the steps of: a. separating a whole milk as a cream fraction and a skimmed milk fraction, wherein the skimmed milk fraction has a fat content of 0.05%-0.5% by weight and the skimmed milk fraction being subjected to a pre-treatment by pasteurization performed at 70? C. to 75? C. for 10 to 30 seconds without microfiltration or physical separation of microorganism in the skimmed milk fraction; b. subjecting the skimmed milk fraction to a heat treatment, said heat treatment comprising heating the skimmed milk fraction to 152? C. to 165? C. for a time of 500 ms or less; and c. flash cooling of the skimmed milk fraction to a temperature at or below 70? C.

2. The process according to claim 1, wherein the skimmed milk fraction of the step c., which has been subjected to the heat treatment of the step b., contains denatured ?-lactoglobulin in an amount of 40% or less of a ?-lactoglobulin originally present in the skimmed milk fraction of the step a.

3. The process according to claim 1, wherein the step b. takes place directly after the pre-treatment.

4. The process according to claim 1, wherein the heat treatment comprises heating the skimmed milk fraction to 153? C. to 159? C. for the time of 500 ms or less.

5. The process according to claim 1, wherein the heat treatment is performed for 300 ms or less.

6. The process according to claim 1, wherein the skimmed milk fraction obtained by separating the whole milk in the step a. has a fat content of 0.05%-0.3% by weight.

7. The process according to claim 1, wherein the cream fraction is treated at 100-180? C. for a period of 10 ms to 4 s.

8. The process according to claim 1, further comprising the step of: d. blending the skimmed milk fraction which has been subjected to the heat treatment of the step b. with a heat treated cream fraction to obtain a milk product having a fat content of 0.5% by weight to 4% by weight.

9. The process according to claim 1, wherein the whole milk, which has been subjected to the heat treatment of the step b., maintains 80% by weight or more of a whey protein originally present in the whole milk.

10. The process according to claim 1, wherein the skimmed milk fraction of the step c., which has been subjected to the heat treatment of the step b., contains denatured ?-lactoglobulin in an amount of 30% by weight or less of a ?-lactoglobulin originally present in the skimmed milk fraction of the step a.

11. The process according to claim 1, wherein the skimmed milk fraction of the step c., which has been subjected to the heat treatment of the step b., contains denatured ?-lactoglobulin in an amount of 20% or less of a ?-lactoglobulin originally present in the skimmed milk fraction of the step a.

12. The process according to claim 1, wherein the heat treatment is performed for 100 ms or less.

13. The process according to claim 1, wherein the skimmed milk fraction obtained by separating the whole milk in the step a. has a fat content of 0.05%-0.1% by weight.

14. The process according to claim 1, wherein the whole milk, which has been subjected to the heat treatment of the step b., maintains 90% by weight or more of a whey protein originally in the whole milk before the separating in the step a.

15. A process for producing a skimmed milk fraction comprising the steps of: a. separating a whole milk into a cream fraction and a skimmed milk fraction having a fat content of 0.05%-0.5% by weight and pre-treating the skimmed milk fraction by pasteurization performed at 70? C. to 75? C. for 10 to 30 seconds directly after the separating; b. heating the skimmed milk fraction to 152? C. to 165? C. for a time of 500 ms or less directly after the pre-treating; and c. cooling of the skimmed milk fraction to a temperature at or below 70? C.

16. The process according to claim 15, wherein the separating comprises centrifugation.

17. The process according to claim 15, wherein the process does not require microfiltration or physical separation of microorganisms in the skimmed milk fraction.

Description

EXAMPLE 1

(1) Whole milk was separated in a cream fraction and a skimmed milk fraction by centrifugation. The skimmed milk fraction was preheated at 72? C. for 15 seconds, i.e. pasteurized, and subsequently heated to 157? C. for 0.09 seconds and flash cooled to 70? C. or below. For comparison purposes a part of the skimmed milk fraction was also after the preheating treated by the standard instant infusion (UHT) process using heating to 143? C. for 6 seconds.

(2) Whole milk was treated similarly as shown in the table below:

(3) TABLE-US-00001 TABLE 1 All figures are in % by weight. Skimmed Skimmed Whole Whole Skimmed milk milk Whole milk milk milk 157? C. 143? C. milk 157? C. 143? C. Feed 0.09 s 6 s feed 0.09 s 6 s Fat 0.05 0.05 0.05 3.90 3.90 3.90 %(w/w) Whey 0.498 0.459 0.274 0.536 0.357 0.236 protein %(w/w) % 7.8 45.0 33.4 56.0 denat.

(4) The data in the table shows that only 7.8% by weight of the whey proteins are denatured by the process according to the present invention. In contrast, 33.4% by weight of the whey protein is denatured for whole milk, which indicated that the amount of fat plays a crucial role in the denaturing of whey proteins in milk and milk derived products.

(5) The data also shows that temperature and time is of importance for the denaturing of whey proteins. Thus, when the treatment regimen for the skimmed milk is changed to 143? C. for 6 s, the degree of denaturation increases to 45.0%. Similarly, the degree of denaturing of whole milk increases to 56.0% when the whole milk is treated at 143? C. for 6 s.

(6) The skimmed milk treated as indicated above may be used in its own right or be mixed with the cream for the preparation of a milk derived product having an elevated fat content. Before the cream fraction is mixed with the treated skimmed milk it may be treated at 147? C. for 1 s, i.e. an UHT treatment. After mixing of the UHT treated cream and the treated skimmed milk the mixture may be homogenized at 240-40 bar.

EXAMPLE 2

(7) Whole milk was separated in a cream fraction and a skimmed milk fraction by centrifugation. The skimmed milk fraction was preheated at 72? C. for 15 seconds, i.e. pasteurized, and subsequently heated to 154? C. for 0.250 seconds and flash cooled to 70? C. or below. For comparison purposes a part of the skimmed milk fraction was also after the preheating treated by the standard instant infusion (UHT) process using heating to 143? C. for 6 seconds.

(8) As a control experiment, milk having a reduced fat content of 1.6% by weight fat was treated similarly as shown in the table below:

(9) TABLE-US-00002 TABLE 2 Fat Skimmed Fat reduced Skimmed milk, reduced whole milk milk 154? C. whole milk 154? C. Feed 0.25 s feed 0.25 s Fat %(w/w) 0.02 0.02 1.60 1.60 Whey protein 0.606 0.549 0.542 0.396 %(w/w) % denatured 9.4 26.9 Beta-Lacto- 5465 4560 4888 2590 globulin [ppm] % Beta-Lacto- 16.6 47.0 globulin denaturation

(10) The data in the Table 2 shows that only 16.6% by weight of the Beta-Lactoglobulin proteins are denatured by the process according to the present invention. In contrast 47.0% by weight of the Beta-Lactoglobulin is denatured in fat reduced whole milk, which indicates that the amount of fat plays a crucial role in the denaturation of Beta-Lactoglobulin and whey proteins, when processed at short holding times <0.5 sec and very high temperatures >150? C.

(11) The data in the Table 2 with only 16.6% denaturation by weight of the Beta-Lactoglobulin proteins in skim milk is crucial information, because cooked taste in milk is known to be more pronounced in milk with high Beta-Lactoglobulin denaturation, like >40% denaturation, more likely in >60% denaturation and even more likely in >80% denaturation as in conventional UHT or Autoclaved milk. Pasteurized milk, i.e. milk treated at 72? C. for 15 s is known to have also close to zero denaturation of Beta-Lactoglobulin and also known to have no cooked taste.

(12) The data in the Table 2 also shows that only 9.4% by weight of the whey proteins in the skimmed milk are denatured by the process according to the present invention. In contrast, 26.9% by weight of the whey proteins is denatured in fat reduced whole Milk. The data suggest that the amount of fat plays a crucial role in the denaturation of whey proteins, when processed at short holding times <0.5 sec and very high temperatures >150? C.