An active dry yeast is dramatically different from a yeast
culture.
IntroductionIn the dairy industry several distinctlydifferent
types of yeast products are marketed and are incorrectly
groupedtogether in terms of their characteristics, their mode of
actionand their effect on the animal. One ofthe major distinctions
within productsthat are often referred to as "Yeasts" isthat of
Active Dry Yeast and YeastCulture. There is no similaritybetween
these two dramatically differ-ent types of products.
Active dry yeastsActive dry yeasts (or "live yeasts") consist of
viable active yeast cells thatdirectly affect the rumen
fermentationprocess. An active dry yeast is produced by drying a
cream yeastunder specific conditions to preservethe viability and
fermenting power. It isa pure product without any of the
carriers/fillers found in yeast culture products.
There are thousands of different strainsof yeast, each with its
own identity andfunction. Each strain has a specificgenetic make up
and has its own characteristics. Companies producingactive dry
yeasts profile and select particular strains based on their
function and the specific outcome thatis desired. The technology
to selectstrains for specific functions is being utilized by the
wine making, brewing,baking and, more recently, by the animal and
human nutrition industries.The selection process is complex
andrequires strict selection procedures toobtain and ensure strain
purity.
Lallemand has become the global technological leader in
screening andselecting yeast strains based on specific functions.
Lallemand scientistsuse "DNA fingerprinting" technologyto identify
specific strains and help verify that they will produce the
desiredoutcome in brewing, baking, winemaking or nutrition.
Fact SheetActive Dry Yeasts and Yeast Cultures
LALLEMAND ANIMAL NUTRITIONTel: (800) 692-4700 Email:
[email protected]
www.lallemand.com
Selection and Screening of SC 1077The species of yeast,
Saccharomyces cerevisiae, is on the U.S. Food and
DrugAdministration GRAS (Generally Regarded AsSafe) list, meaning
it can be direct fed to animals. However, under the species name
ofSaccharomyces cerevisiae there are thousandsof different strains.
Each strain is unique in termsof its characteristics and its effect
on a given fermentation process.
Lallemand researchers, through a three-yearresearch program,
identified a specific yeaststrain that would enhance and improve
therumen environment, help control pH andimprove animal
performance. That strain, SC1077 is now commercially available to
dairyproducers as Levucell SC, rumen specific yeast.Today there are
more than 40 peer reviewedpublished papers on the mode of action
andbenefits SC 1077.
An active dry yeast, such as Levucell SC, rumenspecific yeast,
is fed at a significantly lower levelthan yeast culture products
because it is the probiotic effect of the yeast,not the direct
nutritional effect,that benefits the animal.
Yeast CulturesUnlike active dry yeasts that are
metabolicallyactive in the rumen, yeast cultures contain negligible
counts of live cells and do not have aprobiotic effect on rumen
fermentation.
They are made by drying a cream yeast containing nutritional
metabolites onto a graincarrier. Regardless of the strain, all
creamyeasts have a similar nutritional composition(amino acids, B
vitamins, etc) therefore, specificstrain identity is not as
important in yeast cultureproducts.
Yeast culture products contain dead yeast cells,the metabolites
made by the yeast cells when fermenting, and a carrier upon which
the creamyeast is dried. The beneficial effects of thesemetabolites
are not well defined and are oftenreferred to as unidentified
growth factors.Typically, a yeast culture product is fed at
largeramounts (2 oz./head/day) than active dry yeastproducts (0.5 -
5 grams/head/day).
DNA fingerprints of four different
Saccharomyces cerevisiae yeast strains
Diamond Vmagnification x10
Levucell SCmagnification x10
Example of a yeast culture Example of an active dry yeast
Parameters/Yeast Sources Yeast Culture Active Dry Yeast
Proportion of Live Cells (% in Weight)
0-1% 100%
N Live Cells (cfu/g) 102 - 104 >15 x 109
Active Product Fermentation metabolitesNot identified (enzymes?
vitamins?)
Live yeast;Some products arewell identified strains, othersare
generic
Process X Fermenting medium contains corn, wheat midds,corn
gluten, rye midds, malt,cane molasses...X Drying process with
fermenting medium and micro-organisms dried togetherX Deactivated
micro-organisms + eventual dilutiononto carrier
X Selection of strainX Multiplication in fermentors with
molasses (richin sugar)X Separation of cream yeastfrom molassesX
Drying in specificconditions to preserve viability + eventual
coating if necessaryDiamond V is a registered trademark ofDiamond V
Mills, Inc.
