Optimization of fluidized bed drying of Lactiplantibacillus plantarum grown in sustainable culture media for winemaking application

Marina E. Navarro¹Manuel Angel Morales²Natalia Soledad Brizuela¹Adriana C. Caballero²Andrés Reyes-Urrutia²Fausto Vicente²LILIANA CARMEN SEMORILE¹Bárbara M. Bravo-Ferrada¹Elizabeth Tymczyszyn^1*

• ¹National University of Quilmes, Bernal, Argentina
• ²Universidad Nacional del Comahue, Neuquen, Argentina

In winemaking, lactic acid bacteria (LAB) play a key role by driving malolactic fermentation, improving microbial stability and reducing wine acidity. The large-scale development of LAB starter cultures requires cost-effective biomass production and preservation methods. Thus, the present study aimed to evaluate fluidized bed drying as a cost-effective and sustainable alternative method for the preservation of Lactiplantibacillus plantarum UNQLp 11, cultured in media based on apple pomace (AP) and whey permeate (WP). The maintenance of the malolactic activity of UNQLp 11 after preservation was also assessed. The fluidized bed drying process at 45 and 60 °C led to reductions in cell viability ranging from 3 to 5 log units, with survival depending on the culture medium, pH, and drying time. The best performance was obtained at 45 °C for 35 min with final counts reaching 8.3 log CFU/g in the WP-based medium and 7.0–7.4 log CFU/g in the AP-based medium. After 12 months of dried pellet storage at 4 °C in a vacuum-sealed packaging without light, cell viability was well preserved, with losses as low as 1 log unit when the final aw was maintained between 0.10 and 0.33. Winemaking trials demonstrated that cultures in WP-based medium retained malolactic activity after storage, consuming 70–100% of malic acid in synthetic wine and up to 80% in Malbec wine. In contrast, cultures in AP-based medium required rehydration with MRS broth to recover their functionality to levels comparable to those of cultures in WP-based medium. Overall, these findings indicate that fluidized bed drying is a suitable alternative to freeze-drying, capable of producing LAB cultures with long-term stability and technological functionality. However, further optimization of the drying conditions and protective strategies is required to maximize the direct industrial applicability of WP and AP cultures.