15  Svavling

Varför? Missgynna andra mikroorganismer. Minska maillardreaktionen vid pastörisering. Minska oxidering.

Well it’s impossible to say exactly. So much depends on the type of yeast and its history, and the nutrient availability. But pretty much all winemaking strains of Saccharomyces can tolerate 1 ppm of molecular SO2, and many up to 4 times that AFAIR.

To translate 1 ppm of molecular SO2 to free SO2 at any given pH, see the various charts and spreadsheets all over the Internet, including mine http://www.cider.org.uk/sulphite.html

For example at pH 3.5 in a cider, 1 ppm of molecular SO2 equates to about 50 ppm of free SO2. When binding to cider carbonyls is taken into account, you need a total addition of around about 120 ppm of SO2.

Svaveldioxid 5 g till 50 ml H20 ger 5% lösning. 1 ml/L ger då 50 ppm.

Yes, 20 to 30 ppm looks good to me. Yesterday I just opened a first bottle of a perry I bottled mid December. This was an earlier season perry with Thorn and Ure pears, which fermented very fast. I was able to stabilize it at SG1.011 after multiple rackings and bottled with 30 ppm of sulfite, 8 g/L of sugar (which raised SG to 1.0135) and 10 ppm of dry yeast. It is very clean, with a perfect sparkle, no off flavor. For my part, I tend to use sulfite only on early batches as it is warmer for the beginning of fermentation, which leaves the door open for other unpleasant organisms - in particular I have had some brett proliferation in 2021 and (to a lesser extend) in 2022, which can give a quite nasty funk. But this only happened on early batches, and we had a very warm fall in 2021. The bulk of my batches are started when temperatures are colder and don’t get this sort of problem even if no sulfite is used (either before fermentation or at bottling).

cider clarifying as it relates to bottle conditioning : https://groups.google.com/g/cider-workshop/c/-i8jPG-FZ8c

“Acetaldehyde, a by-product of oxidation, is associated with odors of bruised apple, nuttiness, or sherry. Upon binding with bisulfite, acetaldehyde becomes odorless, and anthocyanin pigments become colorless (bisulfite bleaching).”

15.1 Kemi

“In wine, SO2 exists in three forms in a pH-dependent equi- librium (Figure 1): molecular (SO2), bisulfite (HSO3 -), and sulfite (SO3 2-). These forms make up what is known as free SO2, meaning it is available for antimicrobial and antioxidant protection. Some amount of the bisulfite form (HSO3 -) will bind to compounds in the wine. Once bound, the SO2 is no longer available to protect the wine. However, free SO2 and bound SO2 are added together to determine the amount of total SO2 (Figure 2).”

“At wine pH, bisulfite is the predominate form, accounting for over 90% of the SO”

“Maintaining 0.5-0.8 ppm of molecular SO2 is considered sufficient to protect Vitis vinifera red and white wines, respectively, from yeast and bacterial spoilage. For non-V. vinifera wines, it is recommended to use 0.8 ppm of molecular SO2 as the target amount for additions. The percentage of molecular SO2 present in wine is directly related to the pH”

file:///home/e/Downloads/FS53.pdf

Andelen obundet mkt beroende av pH (pH>4 blir “allt” bisulfit, varav en del kan binda partiklar)

15.2 Resurser

Sulphur dioxide in winemaking: file:///home/e/Downloads/FS53.pdf

“Concentrations of SO2 are measured and calculated in milligrams per liter (mg/L). Often these are interchangeably displayed in parts per million (ppm); 1 mg/L is equivalent to 1 ppm.” Yeast naturally produce SO2 during fermentation at the rate of 10-20 mg/L (note: some only 3 ppm?)