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==Strain Selection==
The strain of ''Lactobacillus'' is very important. As is explained below, the souring process should not take longer than 2 days, and some strains do not perform well within this timeframe. Not all strains or species are efficient to use for wort souring. ''Lactobacillus plantarum'' has proven to be the most successful species for kettle souring because it produces acidity very quickly, and it is not as vulnerable to temperature shifts, although using any hops will usually completely prevent this species from producing lactic acid. ''L. brevis'' has also been used with some degree of success, depending on the strain. While ''Pediococcus'' is generally not used for wort souring, Bootleg Biology's ''Sour Weapon P'', which is ''P. pentosaceus'', performs well at wort souring (see [[Pediococcus#Commercial_Pediococcus_Cultures|Commercial ''Pediococcus'' cultures]]). The ''L. delbruekii'' culture offered by White Labs is meant for long term souring and is not a good choice for wort souring (other strains of ''L. delbruekii'' might perform better) <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1212455192116026/?comment_id=1212475888780623&reply_comment_id=1212476575447221&comment_tracking=%7B%22tn%22%3A%22R3%22%7D Conversation with Andrew Addkison on MTF. 01/12/2016.]</ref>. Review the [[Lactobacillus#Culture_Charts|''Lactobacillus'' commercial cultures]] before selecting one for wort souring, and review the [[Alternative Bacteria Sources]] page for tips on using alternative sources of ''Lactobacillus'' such as probiotics, grain, etc.
===''Lactobacillus'' Nutrient Requirements===
Different strains of ''Lactobacillus'' are known to have different nutrient requirements, including some metal ions. ''Lactobacillus'' requires manganese, magnesium, potassium, and sodium, with manganese and magnesium being crucial for their growth. Brewer's wort has many of these nutrients naturally, although zinc is generally deficient. One study looked at WLP672 (''L. brevis'') and found that an increase of magnesium resulted in a faster souring phase, while zinc additions slightly slowed the souring phase. This suggests that in at least the case for this strain of ''L. brevis'', zinc additions should be added after the souring phase for yeast health. The addition of zinc also had several effects on the flavor and aroma compounds produced. Therefore, experimenting with different nutrient additions for the souring phase may result in widely different tasting beer <ref>[https://www.mdpi.com/2218-273X/10/12/1599 Chemical Composition of Sour Beer Resulting from Supplementation the Fermentation Medium with Magnesium and Zinc Ions. Aneta Ciosek, Katarzyna Fulara, Olga Hrabia, Paweł Satora, and Aleksander Poreda. 2020. DOI: https://doi.org/10.3390/biom10121599.]</ref>. See [https://www.facebook.com/groups/MilkTheFunk/permalink/4107425732618943 this MTF thread] for more commentary on this study.
==Processes==