Selection of lactic acid bacteria for biological acidification

Abstract

Lactic acid bacteria are increasingly used not only for malolactic fermentation (MLF), but also for biological acidification through the conversion of sugars into lactic acid. This study selected strains according to SO₂ resistance, rapid MLF, high lactic-acid production from sugars, pH reduction, and inability to produce biogenic amines. A total of 270 isolates from musts of different origins were identified by 16S-ARDRA and typed by RAPD, yielding 83 distinct strains. They were screened for biogenic-amine production, growth at pH 4.0 and 3.7, resistance to 3 g/hL SO₂ at pH 3.8, MLF performance and acidifying activity. Growth was monitored by plate counts, while acids and amines were analysed by HPLC. Most strains did not produce biogenic amines. PN166, PN181, PN106, PN125, and PN217 depleted malic acid within 24–48 h and produced the highest amounts of lactic acid. Twelve strains were subsequently tested in Muscat must. PN166, PN181 and PN19 produced the greatest acidification and were identified as the most promising strains for biological acidification.

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Acknowledgements

This project was funded by the Spanish Ministry of Science and Innovation through the Knowledge Generation Programme (PID2022-1398680B-C31).