AU2015101575A4 - Process for producing reduced-lactose high protein milk - Google Patents

Abstract

Abstract A method of producing a commercial natural milk product that has an increased level of protein and reduced level of lactose; said process including the steps of: subjecting skim milk to an initial separation process that is designed to produce a high protein retentate stream and a low protein permeate stream; subjecting the permeate of the said separation process directly to reverse osmosis filtration (RO); and directly combining the filtrate of the RO process and the retentate of said separation process in appropriate proportions, with or without other natural milk fractions, to produce a natural high protein, reduced lactose milk.

Description

1 PROCESS FOR PRODUCING REDUCED-LACTOSE HIGH PROTEIN MILK Technical Field [0001] The invention relates to the field of commercial dairy and milk product manufacture. In particular, the invention relates to an improved process for producing commercial milk having desirable properties arising from modification in protein and lactose levels. Background of the Invention [0002] As consumers become more sophisticated in their thinking and food choices around nutrition, it becomes necessary for the food manufacturer to respond to these consumer wants by developing a range of products that are tailored to the various particular health concerns. [0003] One such consumer want is for 'natural' food products and higher protein food products, which are both perceived to have health benefits. Another consumer want is for reduced lactose in milk products, which is also perceived to have health benefits. This extends to a desire for high protein and reduced lactose milk and dairy products. [0004] High protein or zero lactose milk products are known in the art, but one drawback they have is that they can be seen as 'contrived' - that is when they are produced as an amalgam of different or 'non-natural' materials they can lose their appeal as a healthy 'natural' product. [0005] Previous attempts to achieve this have been marked by being very complex and therefore requiring higher manufacturing costs, or have involved the use of additives, water, and/or enzyme treatments which can adversely affect the sensory properties of the final product, and which do not allow the final product to be labelled, or perceived by the consumer, as 'all natural'. [0006] Accordingly, it is an object of the invention to provide a process for the manufacture of a high protein and reduced lactose milk that ameliorates at least some of the problems associated with the prior art.

2 Summary of the Invention [0007] According to a first aspect, there is provided a method of producing a commercial natural milk product that has an increased level of protein and reduced level of lactose; said process including the steps of: subjecting skim milk to an initial separation process that is designed to produce a high protein retentate stream and a low protein permeate stream; subjecting the permeate of the said separation process directly to reverse osmosis filtration (RO); and directly combining the filtrate of the RO process and the retentate of said separation process in appropriate proportions, with or without other natural milk fractions, to produce a natural high protein, reduced lactose milk. [0008] For reference, a food which is high in protein, being a "good source" of protein, is defined under the Australia New Zealand Food Standards Code as a food which contains at least 10 grams of protein per serve (where a serve of milk is 250mL, which aligns with the Australian Dietary Guidelines 2013). For reference, lower lactose is as compared to regular full cream milk containing 4.8% lactose. [0009] Ultrafiltration (UF) is a membrane filtration process via which forces, such as pressure or concentration gradients, are used to drive separation through a semi permeable membrane. Suspended solids and solutes of high molecular weight are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the permeate. This separation process is used for purifying and concentrating macromolecular solutions, especially protein solutions. Preferably, the initial separation process is UF. [0010] Reverse osmosis (RO) is the process of forcing a solvent from a region of high solute concentration through a semi-permeable membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. [0011] The process described above represents a relatively simple method for obtaining a commercial milk product that is high in protein and lower in lactose than regular full cream milk. It also allows the high protein and reduced lactose milk product to be made entirely from fresh milk, including streams separated from the original feedstock. This means that the milk can be labelled 'natural' because it is made from fresh milk, including streams derived from the original feedstock skim milk product - there are no additions of liquids or solids from other milk sources required, or the use of water as an additive. [0012] Preferably, the retentate of the RO process is substantially not recombined into the final product. The resulting product will be lower in lactose than regular full cream 3 milk, as the significant majority of the lactose in the low protein permeate stream from the initial separation process will be retained in the RO process retentate. More preferably, the RO retentate is completely discarded from the process. [0013] According to another aspect of the invention, there is provided the use of reverse osmosis (RO) to substantially remove the lactose from a low protein fraction of a partially separated milk, in order to facilitate the production of a high protein, reduced lactose milk. [0014] According to another aspect of the invention, there is provided a high protein milk product produced by any method as described above. [0015] Now will be described, by way of a specific, non-limiting example, a preferred embodiment of the invention with reference to the drawings. Detailed Description of the invention [0016] The invention may preferably be embodied by a commercial scale process for the production of high protein and reduced lactose milk from a skim milk feedstock. [0017] Typically, a skim milk feedstock is used, having a protein level of around 3.2 to 4.2g/1OOmL. The skim milk is pumped through an ultrafiltration (UF) membrane, such as that supplied by Koch Membrane Systems of 850 Main Street, Wilmington, Massachusetts 01887-3388, USA. In particular, this embodiment uses the Dairy Pro UF 10K model 6338, that is made from semi-permeable polyether sulfone (PES), with an observed separation range of 10,000 Daltons. [0018] The retentate from the UF process is high in protein (around 11.9g/1 OOmL in this case, but may vary between 6 - 15g/1 OOmL). The permeate from the UF process has a protein content of around <1.0g/1 OOmL. [0019] The UF permeate is then subjected to further treatment in a reverse osmosis (RO) membrane, such as that supplied by Koch Membrane Systems of 850 Main Street, Wilmington, Massachusetts 01887-3388, USA. In particular, this embodiment uses the KMS HRX membrane, model 3839 HRX-NYV, made from polyamide. [0020] The retentate from the RO process is discarded, and typically has a relatively high lactose content. The permeate from the RO process has a lactose level of practically zero.

4 [0021] The retentate from the UF process and the permeate from the RO process represent high protein and practically zero lactose fractions from the original skim milk feedstock. This means the retentate from the UF process and permeate from the RO process can be blended with the original skim milk feedstock, and with cream separated from whole milk in creating skim milk, to produce a high protein, full cream (or reduced fat) milk that meets the definition of milk, because there are no 'introduced' external constituents in the milk. [0022] For example, a blend of approximately 46.0% UF retentate, 32.1% RO permeate, 13.9% skim milk and 8.3% cream will result in a high protein full cream milk, having a protein level of 6.0-6.5g/1 00mL protein. [0023] This milk will meet the on-pack claim of 'all natural' and 'high protein', having '70% more protein and 25% less lactose than 'regular full cream milk" which may be defined as having 3.4% protein and 4.8% lactose. [0024] It will be appreciated by those skilled in the art that the above described embodiment is merely one example of how the inventive concept can be implemented. It will be understood that other embodiments may be conceived that, while differing in their detail, nevertheless fall within the same inventive concept and represent the same invention.

Claims (5)

1. A method of producing a commercial natural milk product that has an increased level of protein and reduced level of lactose; said process including the steps of: subjecting skim milk to an initial separation process that is designed to produce a high protein retentate stream and a low protein permeate stream; subjecting the permeate of the said separation process directly to reverse osmosis filtration (RO); and directly combining the filtrate of the RO process and the retentate of said separation process in appropriate proportions, with or without other natural milk fractions, to produce a natural high protein, reduced lactose milk.

2. The method of claim 1, wherein the retentate of the RO process is substantially not recombined into said high protein milk.

3. The method of any preceding claim, wherein said initial separation process is an ultrafiltration (UF) process.

4. The use of reverse osmosis (RO) to substantially remove the lactose from a low protein fraction of a partially separated milk, in order to facilitate the production of a high protein, reduced lactose milk.

5. A high protein, reduced lactose milk product produced by the method of any preceding claim.