Liquid yeast is a suspension of baker's yeast cells with a yeast dry matter content usually between 5 and 25% (w/w). Cream yeast is a special form of liquid yeast. It is a product that is obtained directly after the fermentation step in the yeast production process, optionally after one or several washing steps. Cream yeast usually has a dry matter content between 17 and 23% (w/w). Alternatively, liquid yeast can be obtained by resuspending compressed yeast or dry yeast. Liquid yeast can also be in the form of an oil-in-water emulsion as disclosed in JP 2-124054. Liquid yeast also comprises the high- density preparations as disclosed in EP-A-0515406. Liquid yeast products are currently available in two forms. The first one is unstabilised and needs to be stirred in order to prevent sedimentation of yeast cells. The second one is a stabilised one that remains homogeneous due to the presence of a stabiliser such as xanthan gum (EP-A-0461725).

Liquid yeast may further comprise one or more processing aids with dough and/or bread improving properties.

Large industrial bakeries mostly use unstabilised cream yeast in quantities of 5,000-25,000 litres per week. The product is supplied by road tankers and transferred to fixed cream yeast tanks at the bakery. The cream yeast is pumped from those tanks to the mixers, using a ring through the bakery along the dosage points. Medium size bakeries mostly use the stabilised cream yeast that is supplied in containers of 300- 1,000 litres, usually once a week. After use, the containers are returned to the yeast producer where they are cleaned and refilled.

The smallest bakeries currently use no cream yeast. As a result of their small scale, their need for a cream yeast product is only in the order of a few litres to several hundreds of litres per week, but since no suitable packaging means are available, these bakers are forced to remain using block yeast. The advantages of using cream yeast versus using block yeast are manifold including a better accuracy of yeast dosing, the possibility for automated dosing, an increased hygiene in the bakery, a. lower yeast usage and a better dough stability and improved bread quality. Therefore, there is an urgent need at the artisanal bakeries to start using cream yeast instead of block yeast. In Europe, the size of this market segment is 30-40% of total baker's yeast consumption.

Well known packaging means for liquid food stuffs such as milk, fruit juices, carbonated and non-carbonated soft drinks, not producing gas, consist of a single container. This container is usually made from materials such as cardboard (optionally supplied with a plastic or alumina coating), glass, polycarbonab, PET, HDPE (high densiy polyethylene), tinplate and other suitable food grade materials. Other packaging means that are used in the food industry for the storage and supply of for instance wine, cream, egg products and the like consist of a container in a support structure such as a bag-in-box, (jerry) can-in-box etceteras. All these packaging means are equipped with fittings or caps that completely close the container or the bag and are therefore impermeable for both liquid and gas. As a consequence, these packaging means are not suited for the storage of liquid yeast, because the accumulation of gaseous CQ (produced by the yeast cells as a result of their metabolism) will increase the pressure inside and eventually blow up and destroy the packaging means. This will not only waste the yeast product but also lead to potentially dangerous situations for the user.

Figure 1 shows a cardboard box with a volume of approximately 1 litre and supplied with a spout equipped with a screw thread that mounts a ventilating screw cap (VC).

Further dimensions are: a = 19.4 cm, b = 4.0 cm, c = 1.8 cm, d = 7.0 cm.

Figure 2 shows the open folded structure of a cardboard box supplied with an incision as ventilating means. It is made up of panels 1-4 and a fifth panel (5). Upon mounting the cardboard box, the fifth panel is sealed to panel 1. Further dimensions are as in Figure 1. The length of the incision is 15 mm and the distance between the incision (s) and the edge of the horizontal fin crease is approximately 1 mm.

The present invention provides packaging means comprising a container containing liquid yeast characterized in that the container is equipped with means to release overpressure and that the container has a volume between 0.1 and less than 100 liter. Preferably the volume of the container is between 0.1 and 80 litres.

The means to release overpressure may comprise a ventilating cap. A ventilating cap is defined herein as a cap that allows the permeation of gas but does not allow the permeation of liquid. This ventilating cap may be screwed or snapped on the container containing liquid yeast and enables the release of gas from the inside while at the same time the ventilating cap prevents the liquid yeast from leaking out. Suitable ventilating

caps may comprise a sieve that is fixed to the inner side of the cap. These caps may further comprise one or more holes located in the top wall of the cap. When holes are present in the cap, the gas can escape from the container through the holes while in the absence of holes, the gas can escape along the screw thread of the cap. The sieve can be made from a ventilating microporous membrane material that is permeable to gas and impermeable to liquids. Alternatively, the cap may also contain an overpressure releasing mechanism inside the cap that opens above a certain threshold value, for instance 10 mbar.

The means to release overpressure may also comprise one or more incisions made in the container itself, preferably in the top part of the container. The size of the incisions is usually dependant on the size of the container. In addition, the incision may be covered with a ventilating membrane made from a microporous material, preferably on the inside of the container.

In another embodiment, the entire container, or at least a part thereof is made from a microporous material thus providing the container the means to release the overpressure.

Suitable microporous materials to be used for the packaging means of the invention comprise PTFE (polytetrafluoroethylene) or UHMW-PE (ultra high molecular weight such as Solupor"from DSM Solutech, The Netherlands). The microporous material may have a pore size of 0.05-5.0 micron, preferably 0.1-2.0 micron.

The container can be made from any food grade material. For example, the container can be made from cardboard which is optionally equipped with a plastic coating such as polyethylene or an alumina coating. These cardboard containers can be supplied both with one or more ventilating caps or with one or more incisions. Cardboard container containing liquid yeast preferably have a volume between 0.1 and 5 litres, more preferably between 0.25 and 4 liters and most preferably between 0.5 and 3 liters. When cardboard containers are supplied with one or more incisions, then these incisions are preferably located in the top seal of the pack. The incisions may be small linear cuts, made in the centre of the top seal, close to the top horizontal fin crease. The length of the cuts may be between 1-80 mm, preferably between 5-50 mm and more preferably 10-20 mm; the maximum value being dependent on the dimensions of the pack. The distance between the incision (s) and the edge of the horizontal fin crease is preferably less than 5 mm and more than 0.5 mm, more preferably less than 2 mm and more than 05 mm, most preferably

approximately 1 mm. One incision can be made in the seal. In case 2 incisions are present, they can be present in the same horizontal plane or on both sides of the top fin. After the pack has been filled with liquid baker's yeast in the filling machine, the pack's upper seal is made in the normal manner by melting the polyethylene material and by pressing the opposite layers against each other. In this way, the incision is in the"closed"position.

Turning the pack upside down does not lead to leakage of liquid product from the pack.

Only at a certain overpressure, the incision opens and CO2-release may take place.

The container may also be a bottle or (jerry) can made from a suitable foodgrade material such as PET and HDPE. These containers are supplied preferably with a ventilating cap that is screwed or snapped onto the container.

In another embodiment, the packaging means additionally comprise a support structure, such as a box, holding the container. In this case, the container can be made from materials such as polyethylene, nylon, EVOH, MPET or combinations thereof.

Alternatively, the container may be made from microporous materials as described above.

The box can be made from cardboard. It may be coated in order to prevent the carton from becoming weak in case condensation of water would occur. These packaging means may have a volume between 1 and less than 100 liters and preferably have a volume between 5-50 liters and more preferably between 10-30 liters.

The packaging means provided by the invention contain liquid baker's yeast.

Preferably, the liquid baker's yeast has a dry matter content between 5 and 25% (w/w), more preferably between 17 and 23% (cream yeast). Preferably, the liquid yeast further comprises a gum, such as xanthan. The liquid yeast product may also comprise one or more processing aids with dough and/or bread improving properties, such as enzymes, ascorbic acid, emulsifiers and thelike.

The packaging means that are provided by the invention allow the artisanal bakers to use liquid yeast, in particular cream yeast as well, just like largescale bakeries. The packaging means may be used by the baker as follows. After opening the packaging means, the liquid yeast may be transferred from the packaging means to a scabs or a measuring beaker using a simple tap, a dispenser system or a small pipe and a membrane pump or poured directly to the (dough) mixer in case the yeast volume matches the amount of yeast required for the preparation of the dough. The packaging means may also be put in a pressure vessel and external air pressure may be used to empty the container.

Obviously, depending on the demands of the baker, automation of yeast dosage is also

possible, for instance by putting the packaging means on load cells and using a pump, a dosing valve and a computer.

Example 1 Different packaging means were constructed, all containing a carton box and a liner made of LLDPE (Linear Low Density Polyethylene) with a volume of 20 litres and a spout equipped with a screw thread to mount a screw cap. The following caps were used: 1. Closed, non ventilating cap.

2. No cap, i. e. an open packaging means.

3. Ventilating cap with a PTFE membrane fixed to the inside 4. Ventilating cap with 1 hole of 1.0 mm diameter located in the top wall of the cap and a PTFE membrane fixed to the inside of the cap.

5. Ventilating cap with 5 holes of 1.0 mm diameter located in the top wall of the cap and a PTFE membrane fixed to the inside of the cap.

6. Ventilating cap with a UHMW-PE membrane fixed to the inside.

7. Ventilating cap with 1 hole of 1.0 mm diameter located in the top wall of the cap and a UHMW-PE membrane fixed to the inside of the cap.

8. Ventilating cap with 5 holes of 1.0 mm diameter located in the top wall of the cap and a UHMW-PE membrane fixed to the inside of the cap.

All packaging means were filled with circa 15 litres of commercially available stabilised cream yeast ("Koningscream"-produced by DSM in Delft, the Netherlands). To test the effect of overpressure in these packaging means, an incubation temperature of 20°C was used for a period of 3 weeks. All boxes were shaken every 3 days to stimulate gas release from the fluid into the headspace of the bags. The results were as follows : Table 1. Storage of stabilised cream yeast in packaging means supplied with various means to release overpressure at 20°C. Storage time Ventilating means 1 day 1 week 2 weeks 3 weeks Closed cap Liner Box distorted n. a. n. a. expended No cap Good* Good* Good* Good* Cap + PTFE membrane Good* Good* Good* Good* Cap + 1 hole + PTFE Good* Good* Good* Good* membrane

membrane Good* Good* Good* Good* Cap + 5 holes + PTFE membrane Good* Good* Good* Good* Cap + UHMW-PE Good* Good* Good* Good* membrane Cap + 1 hole + UHMW- PE membrane Good* Good* Good* Good* Cap + 5 hole + UHMW- Good* Good* Good* Good* Good* Good* Good* Good* PE membrane Cap + 5 holes + UHMW- Good* Good* Good* Good* PE membrane * Good means that the box remained intact and that no or only a little expansion occurred From these data it can be concluded that the use of a closed cap leads to rapid expansion and distortion of the packaging means. All ventilating caps with either a PTFE or UHMW-PE membrane and with or without holes in the cap itself, have a good performance, comparable to the open packaging means with no cap. When the filled boxes with the ventilating caps were shaken, CO2release from the fluid may temporarily lead to expansion of the liners ; within a few hours, however, the liners resume their original shape.

To determine the CO2 production that has taken place during the storage test of the cream yeasts, their chemical composition was determined, before and after incubation. The CO2 production was calculated using the following reaction equation: 1 glucose # 2 CO2 + 2 ethanol using a molecular volume of 22.4 litre per mole of CO2.

The glucose conversion was calculated from the decrease of yeast dry matter, and the decrease of trehalose and glycogen that took place during the storage period, using the following equation (in grams/kg yeast dry matter) A glucose = A [yeast dry matter * (trehalose % + glycogen %)] * 360/342*10 The results of the calculations are as follows (Table 2): Table 2. Estimated CO2 production after 3 weeks of storage at 20°C Yeast dry Trehalose Glycogen CO2 matter (% on dry (% on dry (I/kg cream (%) matter) matter) yeast)

Control= unstored 16. 30 8. 14 4. 44 0 cream yeast Closed cap 14.80 0.03 0.21 4.8 No cap 15.00 0.03 0.18 4.9 Ventilating cap 14.80 0.03 0.12 4. 9 From these data it can be concluded that during storage, considerable amounts of CO2were formed: approximately 5.0 litres CO2 per kg of cream yeast. Given the fact that the packaging means were filled with approximately 15 litres of cream yeast, it follows that the total amount of CO2 produced inside the 20 litre bags must have been ca.

75 litres of CO2. Part of the CO2 was dissolved in the cream yeastsolution ; part of it has been released in the headspace of the bags where it was ventilated or led to overpressure in the bag. Using the standard CO2saturation values of CO2in water (2.3 g CO2/kg water at 20°C which is equal to 1.1 litre CO2/kg water) it can be calculated that in case of a packaging means with a closed cap, the amount of gaseous CO2 in the 5 litre head space of the liners may have been as high as 60 litres, leading to a theoretical maximal overpressure of 60/5=12 bar, readily explaining the expansion of the bags and the distortion of the boxes that was seen during the test.

Example 2 Different packaging means were used, all consisting of a single 1 litre cardboard box equipped with a polyethylene coating on the inside and a spout equipped with a screw thread to mount a screw cap (see Figure 1). As ventilating means, the same caps were used as those of Example 1. All packaging means were filled with circa 1 litre of commercially available stabilised cream yeast ("Koningscream"-produced by DSM in Delft, the Netherlands). The boxes were stored at a temperature of 20°C during 3 weeks and they were shaken regularly in order to stimulate the release of gas from the cream yeast fluid. The results were as depicted in Table 3:

Table 3. Storage of stabilised cream yeast in packaging means supplied with various means to release overpressure at 20°C. Storage time 1 day 1 week 2 weeks 3 weeks Box Closed cap n.a. n.a. n.a. exploded No cap Good* Good* Good* Good* Cap + PTFE membrane Good* Good* Good* Good* Cap + 1 hole + PTFE Good* Good* Good* Good* membrane Cap + 5 holes + PTFE Good* Good* Good* Good* membrane Cap + UHMW-PE Good* Good* Good* Good* membrane Cap + 1 hole + UHMW-Good* Good* Good* Good* PE membrane Cap + 5 holes + UHMW-Good* Good* Good* Good* PEmembrane * Good means that the box remained intact and that no or only a little expansion occurred From these data it can be concluded that packaging means comprising of a single cardboard container and supplied with a closed cap, cannot be used for the storage of liquid yeast. Packaging means with a ventilating cap are very well suited and behave as good as boxes supplied without cap. When the liquid yeast containing boxes with the ventilating caps were shaken, some expansion occurred, however, within a short time, the boxes resumed their original shape.

Example 3 Different packaging means were constructed, all equipped with a ventilating cap having 1 hole of 1.0 mm diameter located in the top wall of the cap and having a PTFE membrane on the inside: 1.0.5 liter Alumina pouche 2.1.5 liter PET bottle 3.2 liter HDPE bottle 4.20 liter Can-in-box 5.20 liter Jerry can

All packaging means were filled with the appropriate volume of commercially available stabilised cream yeast ("Koningscream"-produced by DSM in Delft, the Netherlands). To test the effect of the generation of gas by the yeast, resulting in a high pressure inside these packaging means, the packaging means were stored at a temperature of 20°C during 3 weeks. The packaging means were shaken regularly in order to stimulate the release of gas from the cream yeast fluid. The results were as depicted in Table 4: From Table 4 it can be concluded that the packaging means supplied with a ventilating cap are very well suited to store liquid yeast. When the liquid yeast containing boxes with the ventilating caps were shaken, some expansion/over pressure occurred, however, within a short time, the boxes resumed their original shape/or release of over pressure took place.

Table 4. Storage of stabilised cream yeast in packaging means supplied with a ventilating cap at 20°C. Storage time 1 day 1 week 2 weeks 3 weeks 0.5 liter pouche Good* Good* Good* Good* 1.5 liter PET bottle Good* Good* Good* Good* 2 liter HDPE bottle Good* Good* Good* Good* 20 liter Can-in-box Good* Good* Good* Good* 20 liter Jerry can Good* Good* Good* Good* Good means that the packaging means remained intact and that no or only a little expansion/overpressure occurred.

Example 4 Two 1-litre cardboard boxes as described in Example 2 were used. One box was supplied with one incision as the overpressure releasing means. Figure 2 shows the open folded structure of the cardboard box. It is made up of panels 1-4 and a fifth panel (5).

Upon mounting the cardboard box, the fifth panel is sealed to panel 1. Further dimensions are: a = 19.4 cm, b = 4.0 cm, c = 1.8 cm, d = 7.0 cm resulting in a volume of the carton of ca 1 liter. Hereto, panel 1 was provided with an incision in the top fin seal. The length of tie

incision was 15 mm and the distance between the incision (s) and the edge of the horizontal fin crease was approximately 1 mm.

Both boxes were filled with circa 1 litre of commercially available stabilised cream yeast ("Koningscream"-produced by DSM in Delft, the Netherlands), and closed afterwards by melting the PE and pressing the opposite layers in a filling machine. To test the effect of overpressure in these packaging means, different incubation temperatures were used: 4°C, 10°C and 25°C. Maximum incubation period was 1 week.

Table 5. Storage of stabilised cream yeast in packaging means supplied with various means to release overpressure at 20°C. Storage temperature of packs Packaging means 4°C 10°C 25°C Without incision Exploded after Exploded after Exploded after 1 week 3 days 1 hour With one incision Intact intact intact From these data it can be concluded that the use of packaging means without incision is readily expanding and distorted, even at low keeping temperature. The ventilating pack, with an incision in the upper seal, has a good performance. When the ventilating pack is shaken, CO2release from the fluid may temporarily lead to expansion of the pack; within a few hours, however, the pack resumes its original shape.