“Let the frost come to freeze them first,
solid as stones,
and then the rain or a warm winter day to thaw them,
and they will seem to have borrowed a flavor from heaven,
through the medium of the air in which they hang.”
— Henry David Thoreau, Wild Apples, 1862
Cidergær, champagnegær, vingær, gær til mousserende vine, mjødgær, gær til mousserende rabarber, gær til kvæder, pærer og hyldeblomstchampagne.
Det canadiske Lallemand, det australske Mangrove Jacks, det tyske Erbslöh, danske Chr. Hansen, det amerikanske Wyeast og White Labs, det engelske Youngs, det tyske Siha og det franske Fermentis fra Lesaffre, det belgiske Brewferm...
Mange producenter og uendelige mange spændende- og forskellige muligheder.
Se, en gærstamme er ikke bare en gærstamme. Hver gærtype er udviklet i forskellige lande og på forskellige lokationer og de kan noget vidt forskelligt. Nogle gærtyper er velegnede til fermentering af cider, andre til at færdiggøre grundvine forud for at blive sat på flaske for en forestående 2. gæring. Nogle kulturgær omdanner alt sukkeret til alkohol og stopper på oe. 1000 eller derunder, andre kan stoppes før gæringen er tilendebragt og vil efterlade en mængde restsukker i den færdige flaske.
Kulturgærtyper kan besidde mange forskellige egenskaber, som henvender sig specifikt til dig, afhængigt af hvilken råvare, der er dit udgangspunkt. De oftest æblesyretunge danske æbler og druer, frugter og bær, kan have brug for at blive fermenteret med en syrereducerende gærtype for at finde den rette sensoriske ballance i slutproduktet.
Dit udgangspunkt for valg af kulturgær skal altid være
The Oxford Companion to Beer definition of
lag phase
Lag Phase is the period between adding (pitching) yeast into wort and the beginning of fermentation. After its arrival in the wort, yeast requires a certain amount of time to acclimate to its new environment and to shift from dormancy to metabolic activity, that is, to active fermentation. During the lag phase, the yeast turns on genetic pathways that allow it to import sugar and other materials needed for cell replication as well as nutrient absorption (fermentation). The lag phase may last anywhere from 3 to 15 h, depending on such factors as wort type and gravity, temperature, yeast strain, yeast health, pitching rate, and aeration.
During the lag phase, yeast cells rapidly absorb available oxygen. Oxygen is needed for yeast to produce important compounds—most significantly sterols (unsaturated steroid alcohols), which are critical in yeast membrane permeability. Although higher temperatures result in a shorter lag phase, brewers usually keep the lag phase temperature below the temperature at which the yeast will eventually ferment. This is because higher temperatures during the lag phase promote the synthesis of such substances as alpha acetolactate, which is a precursor to diacetyl. See diacetyl. Overall, however, yeast produces few flavor compounds and ethanol or other alcohols during the lag phase than it does in the fermentation phase.
The pitching rate, too, plays a significant role in the effectiveness and length of the lag phase. Overpitching can decrease the lag phase, but, because each cell grows the same number of new cells, the result may be too many old, worn-out cells at the end of fermentation. This can lead to off- flavors and low viability if this yeast is subsequently repitched. See pitching.
It is also important that the lag phase not last too long, because cool, well-aerated wort is an ideal habitat for bacteria and wild yeast. It is essential, therefore, that vigorous fermentation with the desired yeast begins before any other organisms can gain a foothold. Although most worts will remain stable for at least 24 h, it is best to err on the side of caution and aim for active fermentation within 15 h.
How much yeast should I use to ferment wine?
For standard primary fermentation inoculation, we recommend an addition rate of 2 lb/1000 gal (25 g/hL) of total juice to achieve a stable and effective population. For high Brix (greater than 25 °B) juices, increase the inoculation rate to 2.8 lb/1000 gal (35 g/hL).
What is the best yeast to use for Cider or Fruit Wines?
The top yeast strains for fruit wine fermentation are K1 (V1116), EC1118, DV10, 71B, D47, M2, VIN 13, VL1, QA23, R2, and W15. For cider fermentation, the top strains are DV10, EC1118, K1 (V1116), M2, Opale, QA23, R2 and VIN 13.
I have high levels of malic acid in my juice. What yeast strain can I use to help lower the acid level?
Some yeast strains are able to metabolize malic acid at greater rates then others. VRB and 71B are yeast strains that have been observed to reduce malic levels.
What is yeast killer factor?
Killer yeast contain a toxin in their cell wall structure that allows them to kill toxin sensitive foreign yeast cells. Most killer strains of S. cerevisiae have good fermentation kinetics and, therefore, have a greater chance of dominating the fermentation. If indigenous yeast is perceived as a potential problem, strains with this factor may be beneficial. Our various yeast strains can exhibit, be sensitive to or have a neutral reaction to this factor.
What is the temperature range of yeast?
Each yeast strain has a temperature range in which it is most active or most sensitive. For specific yeast temperature requirements, please refer to the individual product descriptions.
I have a stuck fermentation and the fructose fraction is higher than the glucose. Which yeast should I use to restart my fermentation?
A good yeast selection for a wine with a high fructose fraction is ICV-KI (V1116). ICV-K1 is fructophilic and a vigorous fermenter. This strain exhibits a killer factor that is helpful when indigenous yeast are still present.
My first attempt to restart a stuck fermentation failed. Should I try again with same yeast strain?
The first yeast strain used may not have acclimated to a difficult condition of the wine or was inoculated with a low population. It is often better to chose a strain better adapted for high alcohol, high SO2 or a competitive atmosphere. Using the same strain may work the second time, but it may not. Make sure to carefully follow a recommended restart protocol.
Can I open and partially use an active-dried yeast culture and reuse the balance at a later date?
A dried yeast culture will begin to absorb moisture as soon as it is opened. This can trigger the yeast to reactivate. If no must or nutrients are available the yeast die or become weakened. An open container also becomes a rich media for possible microbiological growth. It is recommended to close a container tightly immediately after opening. The balance should be used within a short period of time (1-2 weeks).
How should I store my yeast?
Store yeast in a cool, dry environment.