Methods for treatment and storage of whey products

Abstract

The invention relates to methods of treating whey products comprising cooling a heat treated whey product to a temperature of -2°C to 1°C and storing the cooled whey product under aseptic conditions at a temperature of -2°C to 1°C. The invention further relates to methods for increasing the storage life of whey products and to whey products treated with such methods.

Description

[0001]P135830PC00 Title: Methods for treatment and storage of whey products Field of the invention The invention relates to the field of treatment and storage of whey products, in particular treatment to increase the storage life of whey products. Background of the invention Increasing the storage life of milk by subjecting the milk to heat treatment, in particular pasteurization and sterilisation, that inactivate spoilage and pathogenic microorganisms has been carried out for decades. Similarly, heat treatment of whey, a by-product of the cheesemaking process, in particular by pasteurization is increases storage life of whey and whey product. The most rigorous treatment to extent the storage life of milk-derived products is drying and the majority of the milk-based ingredients are transported between countries and continents as a dry powder. In order to increase the storage life of milk or whey at ambient temperature to multiple days, it must be heated to temperatures higher than are achieved during pasteurization, i.e. temperatures of above 100°C. Disadvantages of treatment at such high temperatures are that milk of whey undergoes several changes, such as changes in pH, protein denaturation, calcium precipitation and casein modification. For instance, a major disadvantage is that high thermal treatment denatures the milk whey proteins. In order to increase storage beyond several days, it is known to heat treat milk and whey at lower temperatures, such as by pasteurization which is typically performed at 72°C for 15 seconds, followed by storage of the pasteurized milk at a temperature of 4°C. This way it is possible to obtain a shelf life of approximately 18-20 days. Unlike milk that has been treated under high temperature, pasteurized milk is still suitable for production of most dairy products. In view thereof, pasteurized milk is included in the definition of “fresh milk”. WO 2016 / 204614 describes a method to transport liquid milk during a supply chain time of more than 10 days. In particular it is described that a storage period of at least 40 days is achieved if the temperature of the liquid milk is kept at a temperature of less than 2°C during at least 90% of the duration of the supply chain time. Further known strategies to increase storage life of milk and milk products are to physically remove spoilage and pathogenic microorganisms from fresh milk for example by centrifugation and / or (micro)filtration. It has been described that more than 90% of microorganisms in milk can be removed using such method so that storage life of fresh milk can also be increased by about 10 days. The majority of milk is produced in areas which are located far from locations where milk or milk product is used for consumption and / or preparation of dairy products so that the milk or milk product has to be transported over long distances, e.g. by shipping, which is a cost-effective, but time-consuming transportation method. In addition, due to an imbalance between milk production and consumption of milk and dairy products, long term storage of milk but also of milk products such as whey products is desired. Therefore, there remains a need in the art for improved methods of treatment of whey products, in particular to extend the storage life thereof. Summary of the invention It is an object of the present invention to provide methods for treatment of whey products that overcome one or more of the disadvantages of known methods discussed herein above. In particular, it is an objection of the invention to provide methods for treatment of whey products that increase the storage life thereof. The invention therefore provides in a first aspect a method of treating a whey product, the method comprising cooling a heat treated whey product to a temperature of -2°C to 1°C and storing the cooled whey product under aseptic conditions at a temperature of -2°C to 1°C. In preferred embodiments, said cooling is to a temperature of about 0.5°C and said storing is at a temperature of about 0.5°C. In preferred embodiments, the whey product is cheese whey or casein whey. In preferred embodiments, the whey product is concentrated whey or whey protein concentrate. In preferred embodiments, a method of the invention further comprises a heat treatment. of whey or a whey product to obtain the heat treated whey product. The heat treatment is preferably sufficient to inactivate gram negative bacteria In preferred embodiments, the heat treatment is at least 15 seconds at at least 72°C.In preferred embodiments, the heat treated whey product is a pasteurized whey product. In preferred embodiments, the heat treatment is pasteurization. In preferred embodiments, a method of the invention further comprises concentrating the heat treated whey product. In preferred embodiments, said concentrating is performed by membrane filtration, such as by reverse osmosis (RO), ultrafiltration or microfiltration, or evaporation. In preferred embodiments, said concentrating is performed at a temperature of 0-60°C, preferable 0-5 °C, more preferably 0-2 °C. In preferred embodiments, a method of the invention further comprises bactofugation of the whey product In preferred embodiments, bactofugation is performed prior to concentration of the whey product. In preferred embodiments, said bactofugation is performed at 5000-15000 g, preferably at a temperature of 50-60°C. In preferred embodiments, the cooled whey product is stored for at least 45 days, preferably more than 60 days. In preferred embodiments, the whey product is obtained or produced from milk that has a bacterial count of at most 300.000 cfu / ml. In preferred embodiments, the whey product is obtained from milk that is cooled to a temperature of 10°C or less, preferably 6°C or less after collection. In preferred embodiments, a method of the invention comprises in the indicated order: -optionally bactofugation of the whey product;- concentrating a whey product, preferably whey;- heat treatment, e.g. pasteurization, of the concentrated whey product toobtain a heat treated, e.g. pasteurized, whey product;- cooling the heat treated, e.g. pasteurized, whey product obtained in theprevious step to a temperature of -2°C to 1°C, preferably a temperature of about 0.5°C; -storing the cooled whey product under aseptic conditions at atemperature of - 2°C to 1°C, preferably a temperature of about 0.5°C. In a further aspect, the invention provides a method for increasing the storage life of a whey product, the method comprising treating the whey product with a method of the invention. In a further aspect, the invention provides a whey product treated with a method of the invention. Detailed description The present inventors have previously found that pasteurized milk can be stored for prolonged periods of time, in particular up to 40 days, if it is kept at a temperature of less than 2°C and it is treated aseptically. As demonstrated in Example 1 herein, a procedure was developed that allows for a storage period for milk of more than 100 days if the temperature of the milk is kept below 1°C during essentially the whole time prior to its consumption or further processing. The inventors have now developed a novel treatment procedure for whey products. The exceptionally long storage life that can be achieved with such treatments is in particular advantageous if milk or whey products are produced in farms or facilities in areas which are located far from locations where the whey products are used for consumption and / or preparation of further dairy products so that the whey product has to be transported over long distances. This allows the transportation of liquid (concentrated) whey products by shipping from one continent to another, providing a cost-effective alternative for dry whey product powders, the form in which the majority of whey product is currently transported. The current invention provides a solution to transport liquid milk products over long distances. Transport of liquid milk and whey products has the advantage that the need for solubilization of dried products is avoided. Because drying and solubilization affect the taste of the milk and whey products, the invention further has the advantage that it leads to whey products with improved taste as compared to liquid whey products derived from reconstituted powder products. Further, such long term storage enables to handle imbalances between milk production and variation in consumption of whey products and other dairy products, i.e. the seasonality of milk production and consumption. As shown in Example 2 herein, the present inventors surprisingly found that a specific psychrotrophic bacteria with an unknown To can still grow in pasteurised milk stored at 0.5°C for 8 weeks (56 days), e.g. if the raw milk has a relatively high SPC before pasteurization. Analyses of the milk, including DNA analysis, revealed that this bacterium was the gram positive aerobic spore-forming bacterium Paenibacillus spp. This bacterium is then also able to grow in whey products prepared from milk containing such spores of Paenibacillus spp and stored at e.g. 0.5°C. The fact that spores of Paenibacillus spp are able to germinate and / or the bacteria are able to grow in milk at 0.5° C was unknown before the present invention. A further aim of the present invention is therefor to develop a method to avoid Paenibacillus spp spore germination and / or Paenibacillus spp bacterial growth in whey products by a combination of bactofugation and / or concentration, followed by heat treatment and cooling to a temperature of below 1°C. In a first aspect, the invention therefore provides a method of treating a whey product, the method comprising cooling a heat treated whey product to a temperature of -2°C to 1°C and storing the cooled whey product under aseptic conditions at a temperature of -2°C to 1°C. In a further aspect, the invention therefore provides a method for storing a whey product, the method comprising cooling a heat treated whey product to a temperature of -2°C to 1°C and storing the cooled whey product under aseptic conditions at a temperature of -2°C to 1°C. In some embodiments, the method further comprises concentrating the whey product. In some embodiments, the method further comprises bactofugation of the whey product, preferably prior to an optional concentration of the whey product. The steps of a method of the invention are carried out in the indicated order. In a second aspect, the invention provides a method of treating a whey product, the method comprising:- bactofugation of a whey product;- heat treatment, e.g. pasteurization, of the bactofuged whey product;- cooling the heat treated, e.g. pasteurized, whey product to a temperatureof -2°C to 1°C; and -storing the cooled whey product under aseptic conditions at atemperature of -2°C to 1°C. In a further aspect, the invention therefore provides a method for storing a whey product, the method comprising: -bactofugation of a whey product;- heat treatment, e.g. pasteurization, of the bactofuged whey product;- cooling the heat treated, e.g. pasteurized, whey product to a temperatureof -2°C to 1°C; -storing the cooled whey product under aseptic conditions at atemperature of -2°C to 1°C. In preferred embodiments, the method further comprises concentrating the whey product, preferably following bactofugation and prior to heat treatment of the bactofuged whey product. The steps of a method of the invention are carried out in the indicated order. In a third aspect, the invention provides a method of treating a whey product, the method comprising: -bactofugation of a whey product;- concentration of the whey product- heat treatment, e.g. pasteurization, of the bactofuged and concentratedwhey product; -cooling the heat treated, e.g. pasteurized, whey product to a temperatureof -2°C to 1°C; and -storing the cooled whey product under aseptic conditions at atemperature of -2°C to 1°C. In a further aspect, the invention therefore provides a method for storing a whey product, the method comprising: -bactofugation of a whey product;- concentration of the whey product;- heat treatment, e.g. pasteurization, of the bactofuged and concentratedwhey product; -cooling the heat treated, e.g. pasteurized, whey product to a temperatureof -2°C to 1°C; and -storing the cooled whey product under aseptic conditions at atemperature of -2°C to 1°C. The steps of a method of the invention are carried out in the indicated order. As used herein, "to comprise" and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition the verb “to consist” may be replaced by “to consist essentially of” meaning that a compound or adjunct compound as defined herein may comprise additional component(s) than the ones specifically identified, said additional component(s) not altering the unique characteristic of the invention. The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. The word “approximately” or “about” when used in association with a numerical value (approximately 10, about 10) preferably means that the value may be the given value of 10 more or less 1% of the value. The use of the alternative (e.g., "or") should be understood to mean either one, both, or any combination thereof of the alternatives. The term “viscous” is used herein according to its art-recognized meaning and can be read as having a viscosity higher than that of water at the same temperature. As used herein “milk” refers to any animal milk, in particular cow, sheep, goat, buffalo, camel, llama and deer. In preferred embodiments, the milk is cow’s milk. Further, as used herein, “milk” is liquid milk, including milk that has been concentrated after obtaining the milk. As used herein, “whey” refers to any co-product resulting after the production of cheese, soft or curd cheese or casein from milk. Among the components found in the whey, the largest portion corresponds to lactose, protein, mineral salts and lipids. Casein is precipitated in the cheesemaking process, and the protein in whey is therefore mainly whey protein, but may contain small amounts of casein. The exact composition of whey depends, amongst other, on the type of cheese that is produced. Whey can also be obtained by removing the casein fraction through acid precipitation and microfiltration. As used herein, “whey protein” is intended to include any protein found in the liquid by-products from cheesemaking and casein production by means of acid precipitation and microfiltration. The term “whey product” as used herein refers to unconcentrated and concentrated whey and products obtained from whey. The terms “whey” and “whey product” include, but are not limited to, cheese whey (resulting from cheese production using e.g. rennet or lactic acid-producing bacteria), casein whey (resulting from the production of casein e.g. using mineral acids) and whey permeate (resulting from the production of casein using microfiltration). The term “whey product” also includes whey products that have undergone further processing steps after whey is obtained, such as concentrated whey (obtained after concentrating whey), including whey protein concentrate (WPC) and whey protein isolate (WPI), whey permeate (obtained after microfiltration or ultrafiltration), desalinated whey (obtained after desalination of whey) and hydrolyzed whey (whey that has been enzymatically hydrolyzed) including hydrolyzed whey protein, and specific enriched fractions of whey proteins such as alpha-lactalbumin, beta- lactoglobulin, lactoferrin, etc. In preferred embodiments, the whey product is whey, in particular cheese whey or casein whey, or, if a concentration step is performed, the whey product is concentrated whey, in particular cheese whey or casein whey, including WPC and WPI. The terms “whey protein concentrate” and “whey protein isolate” refer to a concentrated protein preparation from whey. WPI typically contain a higher whey protein content as compared to WPC, with consequently less carbohydrates, lactose and lipids. As used herein the whey product is not a dried whey product. In particular, whey products are liquid or viscous whey products. Methods for making a whey product as defined herein, such as cheese whey, casein whey, concentrated whey, WPC, whey permeate, hydrolyzed whey, hydrolyzed whey protein and enriched fractions of whey proteins are well known in the art and a person skilled in the art knows how to prepare such whey products. In preferred embodiments, the whey product is obtained from milk that is cooled to a temperature of 10°C or less, preferably 6°C or less after collection, and preferably maintained at such temperature until preparation of whey or the whey product. It is preferred that the whey product that is treated with a method of the invention is obtained from processing of high quality milk. As used herein quality of the milk refers to the total mesophilic bacteria count. In preferred embodiments, the milk from which the whey product that is treated with a method of the invention is obtained has a bacterial count of at most 300.000 cfu / ml, more preferably at most 200.000 cfu / ml, more preferably at most 100.000 cfu / ml, more preferably at most 50.000 cfu / ml. A method of the invention optionally comprises a step of concentrating the whey product. In that case, concentration is preferably performed prior to heat treatment such as pasteurization. If a bactofugation step if performed, concentration is preferably performed between bactofugation and heat treatment such as pasteurization. For instance, concentration is performed immediately following bactofugation in accordance with a method of the invention. In preferred embodiments, the whey product that is concentrated is whey and a concentrated whey product is obtained after concentration, including WPC or WPI. Concentration of the whey product, in particular whey is preferably performed at temperatures between 0°C and 60°C, more preferably at a temperature of 0-5 °C. Concentration of the whey product, in particular whey, can be performed using any method known in the art for this purpose. In preferred embodiments, concentration is performed by membrane filtration, including reverse osmosis, ultrafiltration and microfiltration, or by evaporation. In further preferred embodiments, concentration is performed by ultrafiltration. In some embodiments, a method of the invention comprises a step of bactofugation of the whey product, preferably of whey. “Bactofugation” is well known in the art and refers to a procedure to remove microorganisms and spores thereof from milk or a milk product by centrifugation. Bactofugation typically entails centrifugation of the whey product at a speed of e.g.5000-15000 g. In some embodiments, bactofugation is performed at elevated temperatures, such as at a temperature of 40-60°C, or 45-55°C. In preferred embodiments, bactofugation is performed within 96 hours after preparation of the whey product, preferably within 72 hours, more preferably within 48 hours after preparation of the whey product. In further preferred embodiments, bactofugation is performed within 36 hours, more preferably within 24 hours after preparation of the whey product. In preferred embodiments, a method of the invention comprises both a step of bactofugation of the whey product and a step of concentration of the whey product. In such embodiments, concentration of the whey product is typically performed following bactofugation and prior to heat treatment such as pasteurization. “Heat treated” and “heat treatment” as used herein refer to a treatment of preferably at least 15 seconds for at least 72 °C. In some embodiments, a method of the invention comprises a step of heat treatment of the whey product, optionally of the concentrated and / or bactofuged whey product. Heat treatment of the whey product is preferably performed following bactofugation and concentration, if both these treatment steps are performed. If only concentration is performed, heat treatment is preferably performed following concentration. If only bactofugation is performed, heat treatment is preferably performed following bactofugation. Heat treated and heat treatment can be ultra-high temperature (UHT) treatment or moderate or low temperature heat treatment, including pasteurization. UHT treatment involves heating the whey product typically to 138–150 °C. Moderate or low temperature pasteurization typically involves heating the whey product to temperatures of between about 63 °C and 85 °C. In some preferred embodiments, the heat treated whey product is a pasteurized whey product. E.g. if denaturation of protein, which occurs at high temperature treatment, is undesired. In some preferred embodiments, heat treatment of the whey product is pasteurization. “Pasteurization” is well known in the art and refers to a heat treatment at moderate temperature at which most of non-spore forming pathogenic organisms including bacteria, yeasts, and moulds, which may cause food poisoning are reduced to a level at which they do not constitute a significant health risk. Pasteurization conditions are typically designed such as to effectively destroy the microorganisms Mycobacterium tuberculosis and Coxiella burnetii. Pasteurization conditions in a method of the invention are preferably such that the bactericidal effects are equivalent to heating the whey product to 72 °C for 15 seconds in a continuous flow pasteurization or at 63 °C for 30 minutes in a batch pasteurization. These conditions may vary and a skilled person may easily, based on the above, understand what is meant by heat treatment and pasteurization. Heat treatment is preferably performed within 1 day after the whey is obtained from milk, preferably within 4 hours, more preferably 2 hours, more preferably 1 hour after the whey product is obtained. In preferred embodiments, heat treatment refers to a thermal treatment of the, optionally concentrated and / or bactofuged, whey product at a temperature of 60-90°C for 10 seconds to 30 minutes. Pasteurization may for instance be conducted by heating at a temperature of 71-74°C for 15-30 seconds, heating at a temperature of about 63 °C for about 30 minutes, heating at a temperature of about 76 °C for 20 seconds, heating at a temperature of about 74°C for about 25 seconds and heating at a temperature of about 72°C for about 15-20 seconds. For instance, this pasteurization step is conducted at 70-75°C for 10-20 seconds, more preferably about 72°C for about 15-20 seconds, more preferably at 72°C for 15-20, which is also known as High Temperature Short Time (HTST) pasteurization. Heat treatment entails the heating of a composition or product such that the entire composition or product is held at the indicated temperature for the indicated time period. Heat treatment, such as pasteurization, is typically performed by heating the whey product rapidly to the indicated temperature, such as 72°C, keeping it at this temperature for the indicated period of time, such as 15 seconds, and cooling it down immediately thereafter. In preferred embodiments, heat treatment of the whey product is performed within 96 hours after preparation thereof, preferably within 72 hours, more preferably within 48 hours after preparation of the whey product. In further preferred embodiments, heat treatment is performed within 36 hours, more preferably within 24 hours after preparation of the whey product. The whey product is cooled to a temperature of between -2°C and 1°C. In preferred embodiments, the whey product is immediately, e.g. within 1 hour, cooled to the temperature of between -2°C and 1°C after heat treatment. Alternatively, the whey product is immediately, e.g. within 1 hour, cooled after it is obtained, e.g. to below 8°C, such as to 4°C, followed by cooling to a temperature of between -2°C and 1°C. Said cooling to a temperature of between -2°C and 1°C is then preferably performed within 1 day, preferably within 12 hours, more preferably within 8 hours, more preferably within 4 hours, more preferably 2 hours, more preferably 1 hour, after said immediate cooling following heat treatment. Cooling can be performed using any cooling method known in the art, e.g. using ice water. In preferred embodiments, said cooling to a temperature of between -2°C and 1°C, either after heat treatment or after an initial cooling, is to a temperature of 0- 1°C, more preferably about 0.5-1°C. In further preferred embodiments, said cooling is to a temperature of about 0.5°C. In preferred embodiments, cooling is to a temperature of about 0-1°C and storing is at a temperature of about 0-1°C. In further preferred embodiments, cooling is to a temperature of about 0.5-1°C and storing is at a temperature of about 0.5-1°C. In further preferred embodiments, cooling is to a temperature of about 0.5°C and storing is at a temperature of about 0.5°C. A method of the invention may comprise one or more further cooling steps, in particular cooling steps after preparation of whey and prior to any further treatment of the whey, cooling of the concentrated and / or bactofuged whey product. In preferred embodiments, a method of the invention further comprises cooling the concentrated and / or bactofuged whey product to a temperature of 10°C or less prior to heat treatment. In preferred embodiments, the cooling step is cooling to a temperature of less than 8°C, preferably 6°C or less, preferably about 2 °C, prior to heat treatment. A method of the invention may further comprise a desalination step to reduce the concentration of salt in the whey product. Such desalination step can be performed such any method known in the art, such as by ion exchange. Preferably, such desalination step is performed prior to an optional concentration step and prior to heat treatment of the whey product. A method of the invention may further comprise preparing whey or a whey product from milk. Methods for making a whey product as defined herein, such as cheese whey, casein whey, concentrated whey, WPC, whey permeate, hydrolyzed whey, hydrolyzed whey protein and enriched fractions of whey proteins are well known in the art and a person skilled in the art knows how to prepare such whey products. A method of the invention comprises storing the cooled whey product under aseptic conditions at at a temperature of -2°C to 1°C. In preferred embodiments, said storing is at a temperature of 0-1°C, more preferably about 0.5-1°C. In further preferred embodiments, said storing is at a temperature of about 0.5°C. In preferred embodiments, the temperature of the whey product does not exceed 1°C for more than 10% of the storage time, preferably not for more than 5% of the storage time, more preferably not for more than 2.5% of the storage time, more preferably not for more than 1% of the storage time. In preferred embodiments, the temperature of the whey product does not exceed 1°C for longer than 1 consecutive day, preferably not for 4 consecutive hours, preferably not for longer than 3 consecutive hours, preferably not for longer than 2 consecutive hours, preferably not for longer than 1 hour after the heat treated whey product has been cooled. In particular embodiments, the temperature of the whey product does not exceed 1°C after the heat treated whey product has been cooled. This can for instance be achieved by storing the whey product in a temperature controlled refrigerated unit at the desired temperature. "Storage life” as used herein (also known as shelf-life) refers to the time during which the whey product can be stored at a specific temperature before spoilage occurs due to growth of microorganisms. As used herein, the whey product treated in accordance with the invention is considered within the storage life if the total viable count is less than 300.000 colony forming units (cfu) / ml. Total viable count (TVC), is a quantitative estimate of the concentration of viable or live microorganisms such as bacteria, yeast and spores that are capable of growing into distinct colonies in a composition or sample. As demonstrated in the Examples herein, milk treated and stored at a temperature of -2°C to 1°C has a storage life of more than 45 days. To the knowledge of the inventors a longer storage life of fresh milk has not been experimentally demonstrated before. In particular, the present inventors show that milk treated and stored at a temperature of -2°C to 1°C has a storage life of more than 99 days. In preferred embodiments, the cooled whey product is stored for at least 45 days, preferably more than 50 days, more preferably more than 55 days. In other embodiments, the whey product can be stored for more than 60 days, more preferably more than 70 days, more preferably more than 80 days, more preferably more than 90 days, more preferably more than 100 days. In other embodiments, the whey product is stored for more than 60 days, more preferably more than 70 days, more preferably more than 80 days, more preferably more than 90 days, more preferably more than 100 days. In a method of the invention the whey product is stored aseptically. Further, any processing steps that are performed after cooling, such as filling, packaging and transferring of the whey product, are preferably performed under aseptic conditions, also referred to as aseptic processing. For instance, the whey product is preferably aseptically transferred between a container of the facility where a method of the invention is performed and / or the storage facility and a container for long distance transport. Further, the whey product is preferably also aseptically transferred between a container for long distance transport and a container of the destination storage facility. As used herein “aseptic conditions” refers to conditions free from living, in particular pathogenic or spoilage, microorganisms. Similarly, “aseptic processing” refers to processing by which the whey product is processed, e.g. transferred, filled out and / or packaged in sterile container, in a way that sterility is maintained. Aseptic processing and containers are well known in the art and for example described in US3678955, US3871824, US3918678, US3918942 and US3998589. A method of the invention may comprise further steps. For instance, during storage, the containers containing the treated whey product can e.g. be stirred, shaken or turned over regularly, e.g. every 2 hours, half day, day or 2 days, or continuously to prevent sedimentation. Such regular or continuous stirring can be achieved by including stirrers in the containers. These stirrers need to be aseptically fitted into the containers. Further, after cooling the whey product can be filled into smaller containers, e.g. under laminar flow conditions. In some embodiments, a method of the invention comprises a packaging step in which the cooled whey product is packaged into a container. Preferably, the cooled whey product is packaged under aseptic conditions, for example using an aseptic filling system. Such step preferably involves filling the cooled whey product into one or more aseptic containers. Examples of useful containers are glass or plastic bottles, and plastic or waxed paper cartons. When the cooled whey product is transported during storage, the whey product may be transferred, in particular aseptically transferred, between a container of the treatment facility or one of the treatment facilities and the container used for transportation. WO 2016 / 204614 describes suitable containers for transport of whey product treated in accordance with a method of the invention and is incorporated herein by reference. In preferred embodiments, a method of the invention comprises: -heat treatment, e.g. pasteurization, of a whey product to obtain a heattreated, e.g. pasteurized, whey product; -cooling the heat treated whey product obtained in the previous step to atemperature of -2°C to 1°C, preferably a temperature of about 0.5°C; -storing the cooled whey product under aseptic conditions at atemperature of - 2°C to 1°C, preferably a temperature of about 0.5°C. In further preferred embodiments, a method of the invention comprises:- concentrating a whey product, preferably whey;- heat treatment, e.g. pasteurization, of the concentrated whey product toobtain a heat treated, e.g. pasteurized, whey product; -cooling the heat treated, e.g. pasteurized, whey product obtained in theprevious step to a temperature of -2°C to 1°C, preferably a temperature of about 0.5°C; -storing the cooled whey product under aseptic conditions at atemperature of - 2°C to 1°C, preferably a temperature of about 0.5°C. In further preferred embodiments, a method of the invention comprises: -bactofugation of the whey product;- concentrating a whey product, preferably whey;- heat treatment, e.g. pasteurization, of the concentrated and bactofugedwhey product to obtain a heat treated, e.g. pasteurized, whey product; -cooling the heat treated, e.g. pasteurized, whey product obtained in theprevious step to a temperature of -2°C to 1°C, preferably a temperature of about 0.5°C; -storing the cooled whey product under aseptic conditions at atemperature of - 2°C to 1°C, preferably a temperature of about 0.5°C. The methods of the invention advantageously allow whey or a whey product to be stored for period of 100 days or longer, while still allowing for a high variety of applications of the whey or whey product, and without the need for solubilization or reconstitution as is required by dried, powdered, whey products. I.e. whey or whey product treated in accordance with the invention and stored for periods up to or longer than 55 days, or even up to or longer than 100 or 140 days can be used for the production of solid, semi-solid or liquid dairy products, without reduced taste. Before the present invention it was unknown that pasteurization and storage of milk products including whey products at temperatures below 2°C, in particular below 1°C, would still allow for the germination of Paenibacillus spores and / or the growth of Paenibacillus. In particular, it was previously unknown that these spores and bacteria are able to germinate and / or grow at temperatures as low as 0.5°C. Before the present invention, it was further unknown that concentration to reduce of the volume of a milk product by up to 50% or more, which inevitably also increases the bacterial count prior to pasteurization, is possible while maintaining the exceptionally long storage period with only the combination of heat treatment and storage at temperature below 2°C and no further steps that aim to reduce microorganisms. It was further unknown that the combination of concentration and / or bactofugation, of heat treatment and of cooling to and storage at a temperature below 1°C is sufficient for such exceptionally long storage life. As detailed herein above, the exceptionally long storage life that can be achieved with the treatment of the prevent invention is in particular advantageous if the whey is produced in farms or facilities in locations which are located far from locations where the whey product is used for consumption and / or preparation of further dairy products so that the whey or whey product has to be transported over long distances. This allows the transportation by ships, which is a cost-effective, but time-consuming transportation method. As another example, such long term storage enables to handle imbalances between a relatively consistent milk production and variation in consumption of dairy products, i.e. the seasonality of milk. In another aspect, the invention provides a whey product, preferably cheese whey or casein whey, that has been treated with a method of the invention. Preferably, said whey product has been stored for at least 45 days, preferably more than 50 days, more preferably more than 55 days. In other embodiments, the whey product can be stored for more than 60 days, more preferably more than 70 days, more preferably more than 80 days, more preferably more than 90 days, more preferably more than 100 days. In other embodiments, the whey product is stored for more than 60 days, more preferably more than 70 days, more preferably more than 80 days, more preferably more than 90 days, more preferably more than 100 days. Features may be described herein as part of the same or separate aspects or embodiments of the present invention for the purpose of clarity and a concise description. It will be appreciated by the skilled person that the scope of the invention may include embodiments having combinations of all or some of the features described herein as part of the same or separate embodiments. The invention will be explained in more detail in the following, non-limiting examples. Examples Example 1 A test was performed with pasteurized milk in 500 ml carton packages. This milk was bactofuged to reduce the number of bacterial spores sufficiently and is packaged without recontamination with gram negatives. The milk was stored at 0.5 °C and was monitored for standard plate count (SPC) on a weekly basis and a number of times on organoleptic properties during the storage period of > 140 days. The aims were to find out if microbiological quality stays at the desired level in concentrated, pasteurized milk and there is no growth of bacteria, and if organoleptic properties stay at the level of fresh pasteurized milk. To carry out the test raw milk was stored at 4°C for less than 24 hours and skimmed at 50°C. Subsequently, one batch of milk was bactofuged and one batch of milk was not subjected to bactofugation. Subsequently, batches of milk were concentrated to a concentration factor of approximately 3.8 at a temperature of 2°C using a Reversed Osmoses (RO) installation, stored at 2°C, pasteurized at 72°C for 15 seconds, filled under laminar flow conditions and stored aseptically in a temperature controlled refrigerated unit at a temperature of 0.5°C during a period of more than 140 days. During the period of storage the milk was analysed on an interval basis on microbiological, physical / chemical and organoleptic properties. Up until 140 days after storage, the microbiological analyses of the bactofuged and non-bactofuged milk did not show growth of psychrotrophic microorganisms. Organoleptical testing revealed that there were no deviations found in appearance, smell and taste of the milk up until 140 days after storage, as compared to freshly pasteurized milk. The milk further scored better than milk prepared from milk powder in smell and taste. The milk was smooth in appearance, showed no signs of curdling or breaking, had no lumps and no grainy structure. The milk had a normal smell and taste and could be heated to boiling point without separation. Example 2 Procedure Raw milk was concentrated to a concentration factor of approximately 2 immediately after milking at a temperature of 37° C, cooled in ice-water, pasteurized at 72 °C for 20 seconds, filled under laminar flow conditions to prevent contamination with gram negative bacteria and stored in a temperature controlled refrigerated unit at a temperature of 0.5°C during a period of more than 90 days. During the period of storage the milk was analysed on an interval bases on microbiological-, physical / chemical – and organoleptic properties.The following steps were carried out:-Raw milk was concentrated immediately after milking using a Reversed Osmoses (RO) installation, which is connected to a milking carrousel to concentrate the milk directly after milking at a temperature of 37 °C. This was carried out on day 1 between 8.00 -10.00 hours. -The concentrated milk was collected in 25 litre stainless steel cans and cooled in an ice water bath with circulating waterflow. -The cans with cooled concentrated milk were transported in a box with ice-cubes to maintain or lower the temperature to the facility where it was further processed. This was carried out on day 1 between 10.00 and 12.30 hours. -The concentrated milk was pasteurized at 72 °C for 20 seconds and additionally filled, under laminar flow conditions, in 500 ml PE bottles. The bottles were stored in ice-water. This was carried out on day 1 starting 14.00 hours. -The bottles, in ice-water, were transported back to the storage facility and stored in an dedicated refrigerated unit at a set temperature of 0.5 °C. -The stored bottles were turned over every 2 days to prevent creaming of the milk. -The bottles of milk were sampled after arriving at the storage facility and analysed for microbiological status. Together with the samples of the concentrated milk before pasteurization, the concentrated milk directly after pasteurization and the quality results of the raw milk a full set of results was gathered to assess initial microbiological quality. -The stored bottles of milk were sampled every 4 weeks and analysed on bacterial growth by means of analysing the psychrotrophic count and the presence of Listeria. To assess the physical / chemical quality viscosity and pH were analysed every 4 weeks. The analyses were carried out at week 4, week 8 and week 13. - At week 8 and 13 the milk was tested organoleptically. Results Concentration raw milk Based on the analyzed parameters lactose and protein of the concentrated milk compared to the average raw milk it was concluded that the concentration factor is approx.1.7. Table 1: fat, protein and lactose content of raw milk prior to and after concentration after concentration before concentration (%) Fat (%) 9.06 4.46Protein (%) 5.47 3.34Lactose (%) 7.77 4.51Quality of the concentrated and pasteurized milk SPC before pasteurization was relatively high: > 300.000 cfu / ml. SPC after pasteurization was normal. The week 4 sample gave a result for psychrotrophic count which was in line with expectations: < 1 cfu / ml (see table 2). Only psychrotrophic count was analyzed as microbiological parameter during the interval testing because only gram negative psychrotrophic microorganisms (m.o.), are possibly able to grow at the chosen storage temperature and they need to be absent to make a storage period of 90 days possible. The week 8 (table 3) and week 13 (table 4) samples showed that there was growth of psychrotrophic microorganisms to high counts. Analysis of SPC gave the same high results. The type of micro-organism was determined because it was unexpected that any micro-organism could grow at the low storage temperature of 5°C. DNA-typing showed that the high counts were the result of the outgrow of the gram positive aerobic spore-forming microorganism Paenibacillus Borealis. Listeria monocytogenes was not detected. Indeed, the focus of the treatment of milk was originally set on eliminating gram negative psychrotrophic microorganisms such as Pseudomonas to be present in the milk. The fact that Paenibacillus Borealis is able to grow in milk stored at 0,5° C was unknown. Table 2: Microbiological and physical / chemical results Concentrated milk Week 4 Listeria monocytogenes Expectation: Not present Result: Not presentPsychrotrophic m.o. Expectation: < 10 cfu / ml Result: < 1 cfu / mlAcidity fat Result: 0.71 mmol / 100grams Table 3: Microbiological and physical / chemical results Concentrated milk Week 8 Listeria monocytogenes Expectation: Not present Result: Not presentPsychrotrophic m.o. Expectation: < 10 cfu / ml Result: 2 x10e6 cfu / mlAcidity fat Result: 0.77 mmol / 100grams pH Result: pH= 6,64Table 4: Microbiological and physical / chemical results Concentrated milk Week 13 SPC Result: >3 x10e6cfu / ml (6x) Thermoresistent m.o. Result: 130-220 cfu / mlListeria monocytogenes Expectation: Not present Result: Not presentPsychrotrophic m.o. Expectation: < 10 cfu / ml Result: 17 x10e6 cfu / mlAcidity fat Result: 0.88 mmol / 100grams pH Result: pH= 6,58 (6,42)Conclusions It was unexpectedly found that Paenibacillus Borealis can grow at 0.5°C if present in the milk. It is most likely that spores of Paenibacillus Borealis are able to germinate at temperature below 1°C, that Paenibacillus Borealis has a very long lag phase at the used storage temperature of 0.5°C and that it will take several weeks before the log phase starts and growth will occur. The presence of Paenibacillus will limit the possible period of storage of milk. Hence, storage of pasteurized (concentrated) milk for a period of 90 days or longer is only possible when the used (raw) milk is free from psychrotrophic aerobic spore- forming microorganisms such as Paenibaciullus. Since Paenibacillus may be present in raw milk the risk of having psychrotrophic strains in the used milk is present. Example 3 Standard sweet whey resulting from the production of traditional Gouda cheese was cooled to 10 ºC and further processed to whey protein concentrate with 35 % protein on dry matter (WPC 35) by means of ultrafiltration. The retentate, with a concentration factor of about 5, was pasteurised for 15 s at 72 ºC, cooled to 0.5 ºC and aseptically transferred into sterile containers of 500 ml which were stored at 0.5 ºC for further analysis.

Claims

Claims 1. A method of treating a whey product, the method comprising cooling a heat treated whey product to a temperature of -2°C to 1°C and storing the cooled whey product under aseptic conditions at a temperature of -2°C to 1°C.

2. The method according to claim 1, wherein said cooling is to a temperature of about 0.5°C and said storing is at a temperature of about 0.5°C.

3. The method according to any one of the preceding claims, wherein the whey product is cheese whey or casein whey.

4. The method according to any one of the preceding claims, wherein the whey product is concentrated whey or whey protein concentrate.

5. The method according to any one of the preceding claims, further comprising heat treatment of whey or a whey product to obtain the heat treated whey product.

6. The method according to any one or the preceding claims, wherein heat treated whey is pasteurized whey and optionally the heat treatment is pasteurization.

7. The method according to any one of the preceding claims, comprising concentrating the heat treated whey product.

8. The method according to claim 7, wherein said concentrating is performed by membrane filtration, such as by reverse osmosis (RO), ultrafiltration or microfiltration, or evaporation.

9. The method according to claim 8, wherein said concentrating is performed at a temperature of 0-60°C, preferable 0-5 °C, more preferably 0-2 °C.

10. The method according to any one of the preceding claims, further comprising bactofugation of the whey product, preferably wherein bactofugation is performed prior to concentration of the whey product.

11. The method according to claim 10, wherein said bactofugation is performed at 5000-15000 g, preferably at a temperature of 50-60°C.

12. The method according to any one of the preceding claims, wherein the cooled whey product is stored for at least 45 days, preferably more than 60 days.

13. The method according to any one of the preceding claims, wherein the whey product is prepared from milk that has a bacterial count of at most 300.000 cfu / ml.

14. The method according to any one of the preceding claims, wherein said method comprises in the indicated order: -concentrating a whey product, preferably whey;- optionally bactofugation of the whey product;- heat treatment of the concentrated whey product to obtain a heattreated whey product; -cooling the heat treated whey product obtained in the previous step to atemperature of -2°C to 1°C, preferably a temperature of about 0.5°C; -storing the cooled whey product under aseptic conditions at atemperature of - 2°C to 1°C, preferably a temperature of about 0.5°C.

15. A method for increasing the storage life of a whey product, the method comprising treating the whey product with a method according to any one of claim