Bioprotective Effect of Pichia kluyveri and Lactiplantibacillus plantarum in Winemaking Conditions

Consumer demand for wines free of, or with, reduced levels of preservatives provide new challenges for innovation in winemaking. The addition of microorganisms as bioprotective agents to avoid or reduce sulfur dioxide (SO) addition during winemaking is a possible intervention strategy that could be of interest to winemakers. A strain of Pichia kluyveri and one of Lactiplantibacillus plantarum were inoculated into a Nebbiolo red grape must, previously inoculated with a mix of microorganisms to mimic a grape must environment. The synergistic effect of the added strains with no, low (1 g/hL), or moderate (3 g/hL) addition of total SO was explored over two vintages (2019 and 2020). Wine fermentations were monitored for microbiological (yeast and lactic and acetic acid bacterial populations) and physicochemical attributes (standard chemical parameters, chromatic characteristics, phenolic and aroma compounds). Microbiological analyses showed fewer undesired microorganisms, namely Acetobacter aceti and Hanseniaspora uvarum, independently from the strain used; this decrease occurred faster when starter cultures were combined with SO. Chemical analyses revealed less acetic acid and ethyl acetate in the bioprotected wines. The bioprotective ability of the starter cultures occurred in both vintages. This study examines P. kluyveri and L. plantarum as bioprotective agents in winemaking to reduce SO additions during the first steps of wine production.