FAQ
Determination of MCP, DCP, pesticides, acrylamide, histamine etc…
MCP and DCP result from chloride reaction with the glycerol moiety of lipids at acidic pH and high
temperature. It is typically a contaminant of HVP’s resulting from the production conditions. The YE process
is strictly biological and does not give rise to MCP or DCP.
How act β-glucans vs mannans
Mannans are able to bind pathogens which possess a mannose-binding lectin on their surface and
agglutinate them. When present in the digestive tract, mannans will therefore impair the adhesion of
pathogens to the gut cell and help prevent the infection of humans and animals. Through the same
mechanism of lectin interaction, mannan structures can also bind to immunocompetent cells of the digestive
tract and produce a non-specific immunostimulation against pathogens. The beta-glucans, are activators of
the macrophages and can stimulate and stabilize the innate immune response in humans and a wide range
of animals (vertebrates and invertebrates) (see FAQ 16).
How can yeast extracts be used in relation to salt reduction?
Yeast extracts are used in salt reduction as they can bring natural savoury taste, and also because their
flavours participate to restore the savoury perception that is lessened by the salt removal. Each company of
the EURASYP has his own products and solutions for salt substitution depending on the level of reduction
required and the type of application.
How much inactivated Yeast should be used in feed ?
Typically recommended doses of Yeast in animal feed depend upon the animal species : • Poultry : 1 – 2 % as anti-stress factor during medication treatments
• Swine : 2 – 5 % for piglets or 100-150 grams per day at the end of gestation and during suckling
• Ruminants : 0.5 - 2 % for milking cows and fattening of bulls ; 0.5 – 3 % for young calves
• Horses : 1 – 5 % or 100 g/day
• Fur animals (minks, foxes, etc) : 0.5 - 5.0 %
• Pets (dogs, cats) : 1 - 5 %
• Pigeons and fowls : 1 – 4 %
• Aquaculture : (salmon, trout, eel, shrimp, prawn, etc.) : 1 – 5 % (2 – 8 % in fry stage).
For specific applications (tablets, dainties) the percentage can be much higher (up to 100% for tablets).
Shelf life of yeast extracts (general statement).
The shelf life of yeast extract depends on their physical form and storage conditions. Yeast extract powder is
very hygroscopic and must be stored in a dry area. If the product is exposed to high humidity (for example, if
the original packaging is opened or damaged), there is a high risk of lump formation and significant
deterioration in quality. Exposure to high temperatures for long times will lead to the formation of unwanted
colour and flavour. Normal storage temperature should be below 25 degrees Celsius.
No refrigeration is necessary during normal transportation and clearance time at customs, because yeast
extract quality will be preserved at temperatures up to 40 degrees Celsius for periods of up to eight weeks.
Yeast extracts are generally available in three different physical forms: liquid, paste and dry (as powder/
granules). The average shelf life of liquids is 0.5 -1 year, pastes 1 - 2 years and dry forms 1.5 - 3 years,
depending on the exact product type.
What are the main characteristics of Yeast Beta-Glucan ?
• Three major different b- Glucan fractions can be obtained from the Yeast Cell Wall:
An alkaline soluble fraction which constitutes about 20% of the Yeast Cell Wall. 80 – 85 % of this
component is ß-(1,3)-Glucan, 8 – 12 % is ß-(1,6)-Glucan. • An alkaline insoluble Glucan fraction consisting of 85 % ß-(1,3)-Glucan and about 3% ß-(1,6)-Glucan. The
long b-(1,3)-Glucan backbone chains are interrupted with b-(1,6)-Glucan side chains at intervals. Inter- and
intra-molecular hydrogen-bonding leads to the highly stable, insoluble structure. • A second alkaline insoluble fraction is highly branched with ß-(1,6)- and ß-(1,3) bonding. This fraction can
be extracted with acetic acid.
Depending on the chain length and the interval of the side chains, there is partial helix structure to the b(1,3)- backbone of the b-Glucan.
How is Beta-Glucan isolated from Yeast?
The procedure of isolation of high purity yeast b-Glucan follows basically the scheme of cell breakage,
removal of proteins, mannans, lipids and other minor components.
Cell breakage can be effected through mechanical devices such as homogenizers, through boiling of the
yeast cream (whole yeast), or through autolysis. A subsequent alkaline extraction removes a substantial
portion of the mannans and proteins. An acid and organic solvent extraction reduces lipid content. The
resulting material is an insoluble yeast b-Glucan.
A partial solubilization of the b-Glucan can be achieved through different derivatisations, e.g.
carboxymethylation, sulphatization or phosphatization, or through an acid or enzymatic treatment.
Which links (1-3, 1-6,…) in the beta glucans are really active ? (General Information)
Various biological activities have been reported for the ß-glucans either from yeast, algae, mushrooms or
plants. What differentiates the yeast ß-glucans from the plants ones is the structure of the polymers. Yeast ßglucans show 1->3 links with 1->6 ramifications. In their native state, they have a high molecular weight and
are slightly soluble. Plant ß-glucans like oat or barley display unbranched 1->4 linked glucose separated
every two or three units by a single 1->3 linked glucose. They also are of high molecular weight but much
more soluble, forming viscous solutions. Both oat and yeast ß-glucans have been recognized as modulators
of the glycemic response or as effectors of cholesterol lowering. Dealing with macrophage activation and non
specific immunostimulation, the relation of carbohydrates structure to activity is more controversial but there
is a much higher number of publications with ß 1->3 ß 1->6 glucans from yeast than from oat or other
sources like algae (laminarin) or mushroom (lentinan).
In Which Kingdom are Yeasts classified ?
From Aristote till the 1950s, only two kingdoms were considered by taxonomists : the plant and the animal
kingdoms. Yeasts were described as “unicellular plants of microscopic size” (in : Industrial Microbiology,
Prescottt & Dunn, 1949).
In the 1960s, Yeasts were classified within the Ascomycetes, which are part of Fungi, which themselves are
Thallophytes (together with algae for instance), belonging to the Vegetal Kingdom.
Although some discussions still exist within the scientific community, according to the latest taxonomic
studies, living organisms can be classified in 7 Kingdoms instead of 2 : • Animals
• Vegetals
• Bacteria
• Protista (e.g. Algae)
• Chromista (e.g. Kelp)
• Fungi (e.g. Yeasts)
• Protozoa (e.g. Amoebae)
The Fungi Kingdom is divided in 4 phyla (groups) :
• Ascomycota
• Basidiomycota
• Zygomycota
• Deuteromycota
Yeasts belong to the phylum Ascomycota, also called Sac Fungi because they produce spores in little sacs
called asci. The Sac Fungi include the prestigious Morels and Truffles.
Are the Specialty Yeast Products marketed by the EURASYP members produced from GMOs
(Genetically Modified Micro-organisms)?
The Specialty Yeast Products marketed by EURASYP members are produced according to the European
food regulations and from non Genetically Modified Yeast strains.
Does Yeast Extract contain MSG (mono sodium glutamate)?
The amino-acids contained in the Yeast Extracts result exclusively from the proteins present in food grade
Yeasts (baker’s or brewer’s or lactic) which are used to manufacture the Extracts. Those amino-acids contain
a large proportion of essential amino-acids, particularly lysine, together with glutamic acid. The Yeast
Extracts contain a maximum of 18 % glutamic acid on the basis of the total protein content (total glutamic
acid refers to both free glutamic acid and glutamic acid in small peptides). The free glutamic acid content is
between 6 % and 13 % of the total protein content. This free glutamic acid, which is a natural component of
Yeast Extract, plays a major role in its aromatic power. Glutamic acid, also referred to as monosodium
glutamate (MSG) has flavor enhancing capabilities and is associated with Umami, the fifth taste sensation.
All EURASYP members guarantee that the ingredients they market under the Yeast Extract denomination
contain no added glutamic acid or MSG beside the natural one originating from the Yeasts themselves.
Furthermore, due to the usual dosages of Yeast Extracts in finished food products, the quantities of free
glutamic acid brought by Yeast Extracts equal less than 100 mg per 100 g of food, to be compared to 140 or
more mg per 100 g of tomato, peas, corn, fish or mushroom.
What is UMAMI, the fifth taste ?
As well as the traditionally recognised taste sensations of sweet, sour, salty and bitter which Europeans have
recognised for many years, the Japanese have made us aware of a fifth taste sensation, which they refer to
as ‘umami’. This is associated mainly with savoury foods and, like the other taste sensations, helps us to
identify the nutritional benefits of the foods we are consuming.
Umami taste is indicative of high protein foods, particularly meat and fish, and is conferred by amino acids
(the building blocks of proteins) and ribonucleotides (important for energy metabolism, protein production
and cell health). Other foods which are rich in umami taste include cheese, tomatoes and mushrooms.
As with other taste sensations, umami is a result of specific molecules interacting with unique taste receptors
located on the tongue. Work done over recent years in a number of scientific establishments has identified
some of the specific taste receptors and elucidated their probable structure and mode of action. The amino
acid, glutamic acid, has been shown to bind to a receptor which initiates a signal being sent to the brain to
say ‘This is tasty!’ which, in turn, triggers a physical response to consume more of the tasty food.
How does the synergy between ribonucleotides and amino acids (glutamic acid) work?
There is evidence that the same receptors can also bind the ribonucleotides IMP and GMP so causing them
to become more sensitive to glutamic acid. This amplifies the response and heightens the pleasure of the
experience for the consumer.
This synergy between glutamic acid, IMP and GMP had been documented in 1960 by the Japanese
scientist, Kuninaka, many years before the discovery of specific taste receptors. He had carried out
experimental sensory work using mixtures of these molecules which showed that the ribonucleotides,
although virtually tasteless on their own, amplified the taste effect of glutamic acid considerably. The
amplification effect was defined in a formula by another Japanese scientist, Yamaguchi, and is often
represented in graphic form as shown below.
Further work by Yamaguchi on palatability has shown clearly that providing sufficient umami impact in
savoury foods can help to maintain consumer acceptability when salt levels are reduced. Yeast extracts are
able to provide a significant umami effect due to the fact that many of the molecules in yeast are identical to
those found in high protein foods such as meat. By digesting these molecules to their basic building blocks,
the powerful umami taste is released so that it can be enjoyed in your soup, sauce or meal.