Process for producing long-life single-serve wine portions through use of high differential pressure

Abstract

A process for producing long-life single-serve wine portions using high differential pressure to extend shelf life comprises applying high differential hydrostatic pressure to sealed wine containers,

Description

Technical Field The invention relates to the field of Wine manufacturing packaging. In particular, the invention relates to the processing of single-serve packages of wine using high differential pressure for the purpose of increasing shelf life. Background of the Invention Wine is a particularly challenging beverage to pack for numerous reasons. Firstly the chemical makeup of the hundreds of thousands of different styles of wines available on the market at any one time is highly varied, leading to a significant number of different paths to spoilage. Secondly, wine is incredibly sensitive to oxygen contact, with both too much and too little offering different challenges. Too much will destroy fragile flavours, but too little will lead to the development of undesirable compounds such as hydrogen sulphide. Thirdly, wine is vulnerable to damage from a plurality of different microbial elements and the legislative environment means that many chemical preservatives are not approved for use. The generally accepted biggest challenge for wine is oxygen contact. Oxygen reacts with volatile aromatic compounds such as thiols, polyphenols that define colour, flavour and tannins, and alcohol, forming aldehydes, quinones and other undesirable chemicals. Traditionally, sulphur dioxide, in the form of potassium metabisulphite, is added to the wine to act as an antioxidant, binding to the oxygen before it reacts with the other components. Wine preservation devices such as Coravin use inert gases, such as Argon to replace air in the headspace of a container, protecting the wine through reducing oxygen contact and increasing shelf life of an opened bottle. However, the smaller the wine volume, the harder it is to preserve. 1mg of Oxygen that enters through a cork will have half the result on a 1,5L container of wine than it would on a 0.75L container of wine, so shelf life will be increased. For a 0.1L container, typical for a single serve portion or a sample, that 1mg of Oxygen would have 15x the effect than the 1.5L container. A single-serve container is defined as a container which holds a volume of wine that is designed to be consumed by one or more people over a single day, rather than being resealed and stored for a length of time. Consumers who are aiming to drink alcohol in a more mindful and healthy fashion are expressing commercial preferences for smaller containers that do not encourage excess consumption. Prior art, such as Vinovae’s patent for repackaging wine into small PET bottles (US 10,759,553 B2) focuses on the use of inert gas chambers to reduce contact with the oxygen during the repackaging process, however our experimental data shows that this does not solve the challenges of microbial spoilage, which are far more significant than the packaging oxygen for most wine styles. In terms of the microbial spoilage pathway, wines can go off by a number of different means. Acetobacter can react with ethanol to create ethanoic acid and ultimately turn the wine into vinegar. Lactic bacteria can operate on lactic acid in the wine. Yeast can operate on sugars in the wine to cause secondary fermentation and many others can cause the wine to spoil. Standard practice in the wine industry is to clean the bottle before it is filled, and to filter the wine, removing any microorganisms present before it is closed. For smaller containers, though, this is very challenging. When combined with the oxygen challenge, no small (<500ml) container has been proven capable of reliably packaging wines without spoilage. Often, the wine can deteriorate badly in just two weeks at room temperature, to the point where it is no longer drinkable, and certainly does not represent a freshly poured serving from a traditional glass bottle. In flexible packaging, the challenges are even more pronounced than in small glass bottles, as a common technique to destroy microorganisms in the beverage include pasteurisation through application of high heat, which is not suitable for flexible packaging, nor for delicate substances negatively affected by heat, such as wine. It can be used for cider or sangria or even table wines, but not products sold on the basis of their flavour. Filtration will network as the flexible package will not be perfectly sterile prior to filling, unlike a glass bottle which can be sterilised with heat treatment, resulting in the ingress of microbes into the final sealed product, either from the atmosphere in the packaging machine, or from the surface of the flexible packaging material. Therefore, an alternative mechanism is needed to sterilise the final packaged product. Because high differential pressure can be applied to a closed, complete flexible package containing wine, the contents are not subjected to any post-processing contamination with spoiling or pathogenic microorganisms, resulting in a considerably longer shelf life than products which are heat-treated or filtered, then subsequently packaged. The high differential pressure processing acts to inactivate any spoiling or pathogenic microorganisms that have entered the product, with at least a 4 log10 to 5 log10 reduction in active cell count. The organoleptic flavour and aroma qualities of the final product are not affected by the process, maintaining the desirable fresh qualities. While considerable experimental data has been gathered on food processing through the application of high differential pressure to kill microorganisms, even at room temperature, there are considerable engineering challenges to generating and containing the extreme pressures, and in ensuring a flexible package can survive the process without damage occurring, before it can reach a reliable, repeatable commercial process. Limited experimentation has been carried out in use of high pressure on wine in plastic kegs to reduce the amount of preservatives required for long-distance shipping. As yet, there has been no commercial-scale usage of high differential pressure processing on wine, nor has the process been used on the use of flexible containers to solve the critical challenges of these products; there has been no application in terms of the production of small, single-serve quantities of wine, which are highly desirable in the industry.. Flexible containers also have significant challenges for surviving the pressures, but also have significant benefits to the consumer in terms of reduced costs and environmental footprint. The 750ml bottle of wine is seen as the golden standard of wine: it can be stored for up to a century, depending on the closure and the wine style, and may continue to develop desirable flavour compounds. However, it presents a significant barrier to trying new wines. The industry has tried for at least 30 years to explore small containers. Cans do not permit enough oxygen to enter the wine, resulting in several chemical reactions suffering from insufficient oxygen to carry out their usual process. An example of this is the polymerisation of tannins, a group of phenolic compounds which bind together over time, with a small amount of oxygen, smoothing out the wine and creating a more pleasant flavour and feeling in the mouth. Cans have proven inadequate for many styles of red wine because of this. Likewise, there have been challenges with the passivation layer suffering from fractures, allowing a galvanic reaction that creates hydrogen sulphide, smelling of rotten eggs. Finally, as a non-sterile filling process, many wines are not suitable and refermentation has been seen to destroy packaged wines in as little as two weeks. Likewise, bag-in-box and plastic bottles permit too much oxygen, leading to a very short shelf life for many wines. Likewise, some wines are not suitable because of the challenges around sterilisation. The use of high differential pressure leads to a dramatic advance in the shelf life of all wines in small portions. More than 250 different styles of wine have been tested successfully, including those which lasted just weeks at ambient temperature prior to the process. Accordingly, it is an object of the invention to provide a high differential pressure process for reducing the level of active microorganisms in commercial single-serve wine portions that addresses the most important problems associated with the prior art. Summary of the invention According to the first aspect of the invention, there is a process for producing portions of wine with a long ambient temperature shelf life by reducing the level of active spoilage microorganisms in the product, the process comprising the steps of: (a) transferring the wine into a smaller container with as little oxygen contact as possible; (b) sealing the container; (c) applying a source of high differential hydrostatic pressure to the product for a period of time; (d) removing the source of pressure differential; and optionally repeating steps c) to d). It has been surprisingly found that the contact with oxygen during the packaging process does not cause a chain reaction in the wine that leads to its spoilage, as is described in most scientific literature to this date, but that even a small level of microbial contamination causes a far more significant challenge for wines under 15% alcohol by volume, above which many microbial organisms are slowed by the level of alcohol. Through use of the invention, care about oxygen contact during repacking can be greatly reduced as the wine is far more resistant against oxygen damage than previously thought. The difference can be explained by the fact that microbial growth will also reduce the levels of preservatives in the wine, leading to further oxygen contact reacting with the wine, not the preservatives. Preferably the maximum hydrostatic pressure differential applied would be a strong vacuum or a pressure of 6000 bar or higher. Best results have been achieved when the pressure differential is held for between 30 and 120 seconds, preferably between 45 and 90 seconds. What has been especially noted by the inventors is the effect on wines with lower alcohol levels, higher levels of residual sugar and volatile chemicals, or lower levels of free SO2 preservatives. In these wines, the improvement in quality is most dramatic and is key to creating a small portion of these products. In particular, none of the prior art is capable of producing samples of these low alcohol wines. The largest current commercial operation producing small portions of wine in glass tubes requires all wines to be submitted to a laboratory analysis to estimate their suitability for repackaging. They state that non-alcoholic beverages are not suitable; this is because of the potential for microbial spoilage. Other prior art attempts to reduce this through addition of further chemical preservatives which changes the flavour and aroma characteristics of the product. The particular advantage of achieving these levels of pathogen inactivation with such relatively short cycle times and without any changes to the flavour is that the overall throughput of the process can be fully-commercial at scale, while also presenting the product as it would appear in a traditional glass bottle. According to a second aspect of the invention, there is provided the use of a process according to any preceding claim, for the production of a commercial wine product. According to a third aspect of the invention, there are provided commercial wine products produced by the process as described above. Commercial wine products produced according to this process have been shown to have a shelf life of greater than 365 days at ambient temperatures between 10 and 25 degrees Celsius. A preferred embodiment of the invention will now be described, in a non-limiting fashion. Detailed Description of the Invention The invention is embodied in a process involving a high differential pressure vs atmospheric pressure that has been developed for the treatment of wine, to render it microbiologically stable for a commercially-viable time period without need for refrigeration. It will be appreciated that this embodiment is by way of example and that the inventive process could be used to treat a wide range of other beverage products. Small portions of wine in particular are less stable than larger containers, owing to a higher ratio of surface area to volume. Many wines make use of sub-micron filtration to reduce microbial activity, but this relies on being run through a perfectly-sterile packaging process into a perfectly-sterile container, which is not always the case. Filtration is also associated with stripping flavour and texture from the wine, and is not favoured by many winemakers. Other wines add chemical preservatives including but not limited to Potassium Metabisulphite, Velcorin or Potassium Sorbate to provide microbial stability, but consumers are increasingly opposed to use of chemical preservatives and these affect the flavour and are not all suited to all potential microbial contaminants. Through high differential pressure processing, the membranes of the microorganisms, which are at ambient pressure, are exposed to significant stresses, causing them to rupture, rendering it inactive. Carried out in a pressure vessel, this can either be in a vacuum environment, or subjected to high hydrostatic pressure. The time that the wine container is placed under this level of pressure must be consistent with commercial production process requirements and result in elimination or inactivation of a sufficient proportion of the target microorganisms while maintaining the quality and flavour of the beverage. When flexible packaging is used, the invention relies on a strong flexible layer laminated to the oxygen barrier in order to protect it during the application of a high differential pressure. In this embodiment, nylon is used to resist against delamination and puncture. Initial testing of the Process The following test conditions were applied to 12 different wines, covering a range of styles including dealcoholised, natural (without preservatives), low alcohol, aromatic, rich, full-bodied and delicate, including red, white and rose wines. i) A stainless steel tank in an ISO class 7 clean room was sterilised with steam and filled with CO2. ii) The wines were decanted by hand from 750ml bottles into the tank. iii) 50 pouches of laminate aluminium I PE film were formed and cleared of oxygen iv) The wine was measured into 100ml portions and transferred into the pouches v) The pouches were closed and marked with a batch code and filling date vi) Half of the pouches were taken for differential pressure treatment and the other half kept as control samples. vii) The wines were tested at periods of one month, three months and six months. The extremities of the pressure process caused significant damage to several of the pouches, with leaks and delamination occurring. In particular, the oxygen barrier was damaged in many pouches, with the aluminium peeling away from the inner layer of poly-ethylene (PE). This provided three groups to analyse: 1) Control group. Oxygen and microbial exposure during packing, but good oxygen seal so little oxygen contact after sealing. 2) Treated but damaged. Oxygen and microbial exposure during packing. Microbes potentially killed by pressure, but oxygen transfer allowed by damaged aluminium layer. 3) Treated. Oxygen and microbial exposure during packing. Microbes potentially killed by pressure. Little oxygen contact after sealing. This allowed us to isolate the effects of the oxygen on its own and the microbes. Prior art is entirely focused on reducing the packaging oxygen contact, which we deliberately chose to ignore. At two weeks, the untreated dealcoholised wines were refermenting, as evidenced by the pouches inflating through CO2 produced by yeast turning the sugar into alcohol and other microbial damage. The same wines treated with the differential pressure did not suffer the same problem. The untreated samples had to be removed before they exploded through excess pressure. After one month, the first taste tastes and laboratory analyses were performed. Unexpectedly, the count of active microorganisms remained low. However, the difference between the treated and untreated was dramatic. The untreated low SO2 wines had turned rancid, as had several others. The treated ones remained fine. On the wines with damaged oxygen barriers, we started to see the first signs of classic oxidation, with aromas of baked apple appearing, indicating the transformation of alcohol into aldehydes. Of the control group (1), the higher alcohol wines remained in acceptable condition, with a hint of mustiness. However, the lighter wines were in a very poor condition, and many were rancid. All of group (2) were destroyed after 6 months, confirming that the transfer of oxygen into the sealed container was still very important. However, the spoilage mechanism was very different to the control group - wines were overdeveloped, with oxidative flavours rather than rancid. After six months, all of the treated, undamaged wine samples from group (3) remained in perfect condition, compared to freshly-opened 750ml bottles of wine. This proved that the packaging process oxygen contact was largely irrelevant and that the packaging materials were capable of keeping wine perfectly for at least 6 months at ambient temperature. Further testing A further round of testing was carried out on 24 different wines with a different material structure, adding nylon to the Aluminium and PE in order to protect it against the stresses endured during the pressure application. This time, 100% of the wine samples tested were perfect for 6 months at room temperature, even low alcohol, high sugar wines which present the most challenging case. To date, a total of >250 different wines have been tested in the new material and there has been a zero failure rate, even on dealcoholised wines, after 12 full months or longer. Some of these fragile wine were tested in parallel with 100ml glass bottles at the same time, which lasted less than 3 weeks. Wine 1 month 3 months 12 months Treatment Treated Untreated Treated Untreated Treated Untreated 0.5% White Perfect Rancid Perfect Rancid Perfect Rancid 12.5% Sauvignon Blanc Perfect Poor Perfect Rancid Perfect Rancid 13.5% Chardonnay Perfect Perfect Perfect Acceptable Perfect Musty 15% Zinfandel Perfect Perfect Perfect Perfect Perfect Acceptable To date, there is no known reference to the commercial use of this treatment in the processing of commercial wine products of any size, let alone the more fragile smaller portions used for sampling and single-serve.

Claims

1) A process for creating single-serve portions of wine with extended shelf life through the process comprising the steps of:a) Transferring the wine from a larger container into a single-serve container and sealing itb) Applying a source of high hydrostatic differential pressure compared to atmospheric pressure to the sample, to apply stress to the microorganisms in the container.c) Holding the pressure for a period of time until the microorganisms are deactivated.d) Removing the pressure from the container.e) Optionally repeating steps b) to d)2) A process according to claim 1 where the minimum hydrostatic pressure is 10-7 mbar or lower.3) A process according to claim 1 where the maximum hydrostatic pressure is 5000 bar or greater4) A process according to claim 1 where the maximum hydrostatic pressure is 6000 bar or greater5) A process according to any preceding claim, wherein said period of time is between 30 and 120 seconds, preferably 60 seconds.6) Use of a process according to any preceding claim, for the production of a commercial single-serve wine product between 20ml and 500ml volume.7) A commercial wine product produced by a process according to any one of claims 1 to 5.8) A commercial wine product with <13% alcohol by volume according to claim 7 wherein said product has a shelf life of greater than 180 days at 10°C.