Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
  • B65D81/24—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants

Definitions

• the present invention concerns the packaging of bakers yeast and aims at providing packages of such yeast, e.g. in free flowing form, in which when stored under refrigeration the yeast retains essentially its physical and leavening characteristics over extended periods of time.
• Yeast which is to be used for baking purposes is a product based on any of the strains of the species Saccharomyces cerevisiae. There are many strains of yeast that are included within this species, differing from each other, among others, in osmotolerant characteristics, ability to ferment various sugars, resistance to dehydration, etc.
• a yeast product based on any of these strains is produced commercially in a series of fermentations or stages. The yeast is grown under aerobic conditions by the addition of large volumes of air to the growth media.
• Carbohydrates, in the form of molasses, and nitrogen sources, in the form of ammonia are continuously incorporated into the growth media, especially in the last stages of propagation.
• yeast is separated from the other dissolved constituents of the growth medis by centrifugation and ! a number of washing cycles.
• Yeast at this stage at ... about 20t solids content,.is a tan coloured liquid and known in the art as liquid or cream yeast.
• Cream yeast is converted to a plastic or solid consistency by vacuum or other filtration procedures.
• Such yeast product is known in the art as compressed yeast containing approximatel 30t solids and may be molded or extruded into blocks or cubes in which form it is supplied to bakers or for household use.
• yeast product provided to the baker is bulk yeast. This product, almost always at a solids level substantially above 30%, is granulated and provided to the baker as is or treated with a minor amount of drying agent intended to preserve the free flowing characteristics of this type of yeast.
• Still another yeast product available to the consumer is referred to in the art as active dry yeast.
• the initial processes involved in the production of this product are those described for compressed or bulk yeast production, a Saccharomyces cerevisiae strain known as Bios No. 23 being generally used.
• the Bios classification is as per publication by Schultz and Atkin in "Archives of Biochemistry", Vol. 14; p. 369 (March 1947).
• active dry yeast is obtained by any of several processes known in the art.
• the compressed yeast can be converted into spaghetti form and dried on a moving belt under controlled temperature and time conditions.
• Fresh, compressed or bulk yeast is sold principa to bakeries.
• the household consumer has two types of yeasi products available to him. They are fresh compressed yeast packages or cubes, wrapped in aluminum foil, or active dry yeast, packaged in air, vacuum, or under inert gas conditions.
• the fresh compressed yeast cube known in the art as Household Yeast, is distributed as a refrigerated item.
• this product has a shelf life of about 4 to 6 weeks under storage conditions generally referred to as cool and dry.
• the yeast has to undergo special treatment in all stages of its preparation, especially before filtration and packaging.
• the packaging material generally an expensive aluminum foil laminate
• This kind of product, being in cake or block form, has the additional disadvantage of having to undergo dispersion before it can be added to the flour in home baking.
• the product suffers also from other shortcomings such as loss of weight and discoloration if not properly wrapped.
• the development of an active dry yeast product came against the background of the disadvantages exhibited by the household yeast package, and aimed at providing a better product. And indeed the active dry yeast type product has a longer shelf life and has no mold or discoloration problems.
• the active dry yeast has, however, other inherent problems. For one, it is less active than fresh yeast. Moreover, it has to be rehydrated under controlled temperature condictions before it can be used in the baking process, and this can become a major burden to the consumer when attempting to bake yeast leavened goods in a kitchen. Additionally, to achieve a reasonable room temperature shelf life, the yeast may have to be packaged in expensive material such as aluminum foil laminates under inert gas conditions. When adding to this the cost of a very demanding drying prodedure, there results a very expensive product for the household consumer.
• Bakers yeast e. 9 . free flowing, fresh bulk yeast, would be an ideal product for, among others, the household consumer, For the consumer to enjoy all the possible benefits of such a product it would have to come to him in a package which ensures for the yeast the following characteristics:
• Bakers yeast is, however, a potentially problematical product. It comprises a mass of living yeast cells having varying amounts of extra-cellular water in the interstitial spaces between and surrounding the cells. Water is also the largest component of the yeast cell and is referred to as intracellular water. The feel or appearance of compressed or bulk yeast is largely determined by the relationship between the intracellular and extracellular water in a particular yeast product preparation. Obviously, the relative dryness or wetness of a yeast product will affect the tendency of the yeast to stick or coalesce and therefore cause a deterioration in its free flowing characteristics.
• Bulk yeast being In a fine granulated form, provides a relatively large surface area for atmospheric oxygen to interact with the yeast. The process is called respiration and its results are the generation of water, heat, and other products. It is this generation of extra water during handling and storage that can ultimately partially or totally destroy the free flowing characteristics of the yeast product.
• U.S. Patent No. 4,232,045 provides a partial remedy to this problem. It teaches the incorporation into the granulated yeast of a drying agent that will tie up some of the water that may be generated by the process of respiration.
• a bulk yeast produced by the teaching of that patent will indeed have an improved capacity to retain free flowing characteristics over extended periods when packaged in especially designed polyethylene lined bags and held under refrigerated conditions.
• a method of preparing a packaged yeast product wherein fresh free-flowing bulk yeast is introduced into a pliable bag whose oxygen permeability at 1 atm. pressure differential across the material does not exceed about 1 000 cm 3 /m 2 per day and whose carbon dioxide permeability at 1 atm. pressure differential across the material does not exceed about 4000 cm 3 /m 2 per day, the amount of yeast in the bag being so dosed that the bag is not full to capacity, the so filled bag is sealed hermetically and is then left at a temperature within the range of 0-20°C to unable the occurrence of autofermentation without affecting deleteriously yeast quality thereby to produce carbon dioxide and inflate the bag.
• air present in the head space of the bag is expelled as far as possible by squeezing before the bag is sealed.
• the yeast in the sealed bag is under what may be termed anaerobic conditions characterised by the presence of mainly a carbon dioxide atmosphere.
• anaerobic conditions characterised by the presence of mainly a carbon dioxide atmosphere.
• the prior art teaches that yeast may not be stored under anaerobic conditions since under such conditions the leavening capacity is significantly reduced.
• the prior art further teaches - see for example British patent specification No. 966,984 and "The Yeast" by S. Burrows referred to above - that carbon dioxide must be continuously removed from stored yeast. It was therefore completely surprising to discover in accordance with the present invention that by storing fresh, free flowing bulk yeast in sealed bags under a carbon dioxide atmosphere, the yeast retains essentially its free flowing characteristics and its leavening strength for extended periods of time.
• the degree of inflation of the bag that is required for thepurpose of the present invention is not critical as long as it is sufficient to produce a protective cushion as specified.
• full inflation of the package is as a rule not required.
• the degree of inflation is obviously directly affected by the rate of autofermentation by the yeast, which in turn is dependent on the temperature of storage.
• any particular yeast strain grown under a particular set of propagation conditions, to a specific nitrogen and phospherous content will have a predictable and known autofermentation profile at a given temperature. It is accordingly possible to alter any of the above to produce a yeast that has a suitable autofermentation profile.
• the handling temperature during the packaging will as a rule be within the range of 10-20°C and the cooling down period may typically be from 24-48 hours.
• volume of bag means the volume of water required to fill it to capacity when empty, and weight ratios of yeast to bag volume of 1:27, have been found to produce satisfactory results.
• weight ratio of yeast to bag volume 1:4 - 1:6 is preferred.
• the material used for making pliable bags whose permeability to oxygen and carbon dioxide is as specified can be of any kind that is inest to the packaged product.
• bags made of plastic polyester sheets, possibly reinforced with small amounts of polyethylene, may be used to advantage.
• Other examples are bags made of .polypropylene or aluminum foil, and there are of course many others.
• Typical plastic material sheets produced by Kibbutz Negba, Israel, have the following permeabilities:
• the present invention provides maximum storage stability that any particular yeast may have.
• any particular yeast may have.
• it is possible in accordance with the invention to store and preserve bakers yeast for household use which hitherto has not been possible.
• This example describes the profile of a particular yeast as regards its potential to produce carbon dioxide by autofermentation and to the leavening activity by the yeast product upon storage for different periods without refrigeration.
• the yeast was propagated under normal conditions to a composition of about 42% total protein (Kjeldahl) and 1.90% P 2 O 5 . After centrifugation and washing, 300 liters of cream yeast were treated with 20 liters of a saturated sodium chloride solution. The treated liquid yeast was vacuum filtered to about 34 per cent solids, granulated through a plate containing 2 milimeter diameter holes, and treated with four per cent Aerosil 200 on a weight basis (a product of Degussa AG of the Federal Republic of Germany).
• the packaging was in a polyethylene reinforced polyester laminate of about 0.06 mm total thickness.
• the actual formation of the packages, filling and heat sealing was by hand.
• the sealed package containing 20 g of free flowing yeast was at about 18°C when the test series was started.
• the volumn of the package when empty was about 550 milliliters. Table I summarizes the results.
• Yeast was propagated, filtered, treated with Aerosil 200, and packaged as under Example 1. Two package sizes, one of 170 milliliters volume and the other of 550 milliliter volume, were filed each with 20 grams of free-flowing, fresh baker's yeast. The results are given in Table II.
• the yeast was propagated as in Example 1, but this time to a protein composition of 41.9t and P 2 O 5 of about 1.70%.
• the filtered yeast contained about 34.7% solids.
• the yeast was packaged in polyethylene-polyester film as in Example 1, but this time in a package that contained 25 g of free-flowing yeast in a total package volume of about 100 milliliters.
• the yeast was packaged on a commercial packaging machine supplied by Rouse of Barcelona, Spain, model 1214 T. The yeast packages were stored at 15-20°C and the observations made after 14 days of storage are recorded in Table III.
• This example illustrates the potential of storage stability that our invention may impart to free-flowing, fresh baker's yeast under various temperatures.
• the yeast was propagated and treated as under Example 3 and stored under the various storage conditions as listed in Table IV. Before storage, the temperature profile of the yeast during preparation and packaging was:
• the storage series started with the yeast being at 17°C and having generated about one ml of carbon dioxide per gram of yeast at this point.
• This example illustrates the superiority of a polyester laminate over polyethylene which has inherently a certain degree of permeability to oxygen and carbon dioxide.
• the yeast was propagated, filtered, treated with Aerosil 200, and packaged as under Example 1.
• Two types of packaging materials were compared. Polyethylene film alone was compared to a leminate of polyester. In the first case 20 g of free-flowinq, fresh bakey's vas sealed in a polyethylene package with a potential volume of about 170 ml., the polyethylene being of 0.05 mn. thickness. In the second instance, 20 g of similaz yeast was sealed in a polyester laminate with a potentlal volume of 550 ml., the laminate being of 0.06 mm total thickness. No attempt was made to squeeze the head space air out before heat sealing. In both cases the temperature history of the yeast was identical and thus:
• the storage started at 18°C and was at room conditions in a temperature range of 15-20°C.
• the results were:
• This example compares the permeability characteristics of three different plastic materials in terms of the degree of head space inflation of the yeast package as a function of storage temperature.
• This example compares the results obtained upon storage of yeast in polypropylene and polyester bags in accordance with the invention.
• This example compares the results obtained in accordance with the invention with two kinds of yeast.
• This example shows the leavening activity of yeast packaged in accordance with the invention in bread dough formula after different storage times at 5°C.

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• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Mechanical Engineering (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
• Bakery Products And Manufacturing Methods Therefor (AREA)
• Packages (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=8193501

Family Applications (1)

Country Status (2)

Cited By (1)

Citations (3)

• 1985
  • 1985-01-11 ZA ZA85281A patent/ZA85281B/xx unknown
  • 1985-05-14 EP EP85105958A patent/EP0201616A1/de not_active Ceased

Patent Citations (3)

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