Classifications

• • A—HUMAN NECESSITIES
  • A21—BAKING; EDIBLE DOUGHS
  • A21D—TREATMENT OF FLOUR OR DOUGH FOR BAKING, e.g. BY ADDITION OF MATERIALS; BAKING; BAKERY PRODUCTS
  • A21D8/00—Methods for preparing or baking dough
  • A21D8/02—Methods for preparing dough; Treating dough prior to baking
  • A21D8/04—Methods for preparing dough; Treating dough prior to baking treating dough with microorganisms or enzymes
  • A21D8/047—Methods for preparing dough; Treating dough prior to baking treating dough with microorganisms or enzymes with yeasts
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
  • C12N1/04—Preserving or maintaining viable microorganisms

Definitions

• This invention relates to a composition for the rehydration of yeast, an active dry yeast and to a process for rehydrating yeast.
• Yeast is widely used in the food industry, most particularly in the making of bread. Yeast is supplied in both dry and paste forms, the dry form being preferred because of its longer shelf life. However, the yeast must be moist when used, and the dry form must therefore be rehydrated prior to use. As yeast is inherently hydrophobic, a rehydrator is generally necessary, this being a chemical compound added to yeast during the drying process, usually at the stage where a yeast slurry is finally converted to the dry form. The presence of the rehydrator makes rehydration possible.
• the rehydrators in universal use are sorbitan monostearate and glycerol monostearate, the former being more popular.
• the rehydrator In most countries the rehydrator is used alone, but - 2 - recently there has been marketed an "improved" rehydrator, this comprising sorbitan monostearate with a minor proportion of soya lecithin. It has now been found that sorbitan monostearate can in association with certain ingredients provide a highly efficacious rehydrator.
• a yeast rehydrating composition comprising a blend of sorbitan monostearate and at least one stearic compound having a maximum HLB value of 12.5 the sorbitan monostearate and the stearic compound being present in the composition in a weight ratio of between 19:1 and 1:1.
• the invention also provides a dried yeast composition
• a dried yeast composition comprising from 0.5 to 2.0% by weight of the dried yeast of a composition which comprises sorbitan monostearate and at least one stearic compound having a maximum HLB value of 12.5, the sorbitan monostearate and the stearic compound being present in the weight ratio of from 19:1 to 1:1.
• a process for the rehydration of dried yeast comprising the step of combining with water a dried yeast which comprises from 0.5% to 2.0% by weight of the dried yeast of a composition which comprises a blend of sodium monostearate and at least one stearic compound having a maximum HLB value of 12.5, the sorbitan monostearate and the stearic compound being present in the composition in the ratio of from 19:1 to 1:1.
• stearic compound is meant a chemical compound which comprises at least one saturated C . noir fatty acid chain, or stearoyl group, of the type possessed by stearic acid.
• this compound must also have a maximum HLB of 12.5 (and - 3 - preferably between 5 and 12.5) means that the compound must also comprise some chemical entity, o group, which is water-soluble or -solvatable.
• Compounds of this nature may be ionic or non-ionic, but it has been found that the most effective stearic compounds are anionic.
• Suitable stearic compounds include anionic compounds such as sodium stearoyl lactylate and non-ionic compounds such as sorbitan tristearate ethoxylate which may contain any suitable length ethoxyl chain, compounds having an average ethoxyl chain length of twenty ethyleneoxy units being preferred.
• the stearic compounds preferred for use in the compositions of the invention are anionic compounds and in particular sodium stearoyl lactylate.
• Sodium stearoyl lactylate is known as a dough conditioner and emulsifier (see for example "Bakers Digest", 42. (6) 38-42 (1968)) and has been suggested for use as a component in an emulsifier for active dried yeast (see “Research Disclosure", December 1983, 23606).
• the known art does not teach or suggest the advantageous properties of a combination of compounds such as sodium stearoyl lactylate and sorbitan monostearate as a yeast rehydrator .
• HLB value is used in this specification in its usual meaning of an expression of the Hydrophi le-Lipophi le balance of an emulsifier and is well known in the art of surface active agents.
• the sorbitan monostearate and the stearic compound must be present in the yeast rehydrating composition such that the weight ratio of monostearate to stearic compound lies between 19:1 _ 4 _ and 1:1. It is preferable that the stearic compound be present in smaller quantity than the sorbitan monostearate, and the preferred weight ratios of sorbitan monostearate to stearic compound are from 15:1 to 5:1 and more preferably between 9:1 and 5:1. It is permissible to blend more than one stearic compound with sorbitan monostearate to produce a yeast rehydrating composition according to the invention.
• additives are antioxidants such as ascorbic acid and erythorbates used at a rate of from 5-15% by weight of the total composition.
• the compositions of the invention may be prepared by simply blending together the components using standard equipment. Some stearic compounds lend themselves more readily to processing than others. For example, solids which can be obtained as a powder such as sodium stearoyl lactylate are more easily blended with the sorbitan monostearate.
• the composition is dissolved in water, typically as a 10-15% (wt) solution in which form it may be added to a yeast slurry prior to the drying of the yeast.
• water typically as a 10-15% (wt) solution in which form it may be added to a yeast slurry prior to the drying of the yeast.
• the rehydrating compositions of this invention give rise to a number of other advantages. For example, it has been found that in the drying process when dried yeast is formed from a slurry, the yeast to which such a composition has been added may dry more quickly and/or at lower temperatures than one to which sorbitan monostearate alone has been added. This makes the process more economic and gives a product which when rehydrated is more active than a yeast made using sorbitan monostearate alone. In addition, the storage stability of dried yeast using a rehydrating composition according to the invention is superior to that of the known dried yeasts .
• Composition No. 1 is thus the yeast rehydrating composition in widespread use throughout the world, Composition No. 2 corresponds to the most recent European commercial composition and Composition No. 3 is Composition No. 1 with added a ⁇ tioxidant.
• Three examples of yeast rehydrating compositions of the invention were prepared using the following materials and quantities (expressed as parts by weight) :

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• 1991
  • 1991-05-30 WO PCT/AU1991/000234 patent/WO1991018513A1/en not_active Application Discontinuation
  • 1991-05-30 EP EP91910353A patent/EP0535015A1/en not_active Withdrawn

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