Whenever I use a yeast starter I have overly active fermentation for about four days and then almost no fermentation at all. Is this normal?
To answer this question I will assume that you do not have a chilly root cellar where you are fermenting lagers, and that most, if not all, of your homebrews are ales. I will also assume that you are fermenting your brews in your house at about 72 °F (22 °C).
So, given this information, you want to know if a four-day fermentation period for ales (assumed) is normal and the answer is unequivocally, “Yes!” I think too many descriptions of homebrew fermentations are based on using outdated methods where little packets of yeast were tucked beneath the lids of extract cans and often not used quickly enough.
The quality of yeast, both dried and liquid, is much better these days for a number of reasons — and I think the biggest reason is the strength of the homebrew market and the demand for such products.
Yeast starters increase yeast population and allow the brewer to pitch the yeast at high kräusen, or at least very shortly thereafter. This is the period in the growth phase when cells are actively growing and is named for the yeast froth (kräusen generally translates to ruffle or curly) on top of the fermenting beer. The result of pitching yeast at this stage of growth is what seems to many as abnormally vigorous fermentation that seems to terminate too quickly.
Historically this type of vigor during primary fermentation was extremely important since wort spoilage occurs quickly unless brewing yeast become the dominate microbiological population. When yeast begin to ferment the sugars found in wort, pH quickly drops, alcohol and carbon dioxide concentrations begin to increase and the environment becomes hostile to many aerobic wort spoilers. Sluggish fermentations, on the other hand, leave the wort vulnerable for a longer period and the chance of spoiled beer increases. The problems faced by brewers of the past still exist today, albeit to a lesser degree because of improvements in equipment design and our modern understanding of microbiology, and the benefits of vigorous pitching yeast are equally important today.
Aside from the argument presented above, rapid “normal” beer fermentations generally produce cleaner beer. Many of the off-flavors associated with fermentation, such as ex-tremes with higher alcohols, esters, sulfur compounds, acetaldehyde and diacetyl, are associated with weak fermentations.
On a practical note, we use White Labs WLP001 American Ale for most of our ales at Springfield Brewing Company. Our primary fermentation period for ales with original gravities between 11–14 °Plato usually is complete in three days. There is nothing abnormal with seemingly-short four-day fermentations!
I use Irish moss in my beers, but I still get chill haze. Could it be my mash time? Typically my beers spend 20 minutes in a protein rest at 120–125 °F (49–52 °C) and 40 minutes mashing at 150–160 °F (65–71 °C). then I lauter and boil. I have chill times around 30 minutes using a coil.
North Wales, Pennsylvania
Chill haze is the product of protein and polyphenol (tannin) interactions in beer and occur when beer is chilled, hence the name chill haze. There are various methods aimed at chill haze reduction and they all either are based on reducing the content of chill haze proteins and/or polyphenols. The first thing brewers can do to minimize haze is to begin with low protein raw materials. This is one of the reasons that the protein content and degree of modification of proteins in malt are of importance. Although some brewers frown upon the use of adjuncts, protein dilution of wort is beneficial to a certain degree when higher protein barley is used for malting.
Irish moss added in the kettle reacts with hot break to form larger trub flocs that settle more quickly than smaller flocs. Many brewers today use silica gels prior to filtration to remove even more protein. Polyvinylpolypyrrolidone (PVPP) can be added alone or in conjunction with silica gel, and PVPP is used to remove the polyphenol component of haze. In all cases, a cold aging step prior to packaging allows chill haze to form and permits its removal by gravity sedimentation or filtration. Ale brewers often add isinglass finings to remove yeast, but isinglass also removes some haze forming proteins.
In my opinion neither mash time nor mash profile are significant contributors to chill haze. It is certainly true that longer mashes remove more protein in the mash than shorter mashes, but long mashes and those mashes using low temperature protein rests are not commonly used to specifically address chill haze.
I have a Teutonic view of chill haze control and it seems to work for most of our beers. We begin with high-quality 2-row malt that tends to be on the lower end of total protein (10.5–11%). In the brewhouse we use the mash profile that works for what we want in terms of beer flavor and no special concern is given to haze control. During boiling we evaporate about 6–8% of the kettle full volume and no finings are added. We use no finings before filtration, but we do hold our beers awaiting filtration at 30–32 °F (-1–0 °C) for several days to allow chill haze to form. This works for all of our beers except beers that are dry-hopped as well as those that begin with under-modified Pilsner malt. If I had to correct the haze in these two beers I would use PVPP to go after tannins in dry-hopped beers and silica gel for the haze forming proteins associated with under-modified malt. But a little haze is not a bad thing in some beers and I prefer to let the flavor express itself without excessive meddling.