Impact of different malolactic fermentation inoculation scenarios on Riesling wine aroma

Abstract

During malolactic fermentation (MLF), lactic acid bacteria influence wine aroma and flavour by the production of volatile metabolites and the modification of aroma compounds derived from grapes and yeasts. The present study investigated the impact of different MLF inoculation strategies with two different Oenococcus oeni strains on cool climate Riesling wines and the volatile wine aroma profile. Four different timings were chosen for inoculation with bacteria to conduct MLF in a Riesling must/wine with a high acidity (pH 2.9-3.1). Treatments with simultaneous inoculation showed a reduced total fermentation time (alcoholic and malolactic) compared to the sequential inoculations. No negative impact of simultaneous alcoholic and malolactic fermentation on fermentation success and on the final wine volatile aroma composition was observed. Compared to sequential inoculation, wines with co-inoculation tended to have higher concentrations of ethyl and acetate esters, including acetic acid phenylethylester, acetic acid 3-methylbutylester, butyric acid ethylester, lactic acid ethylester and succinic acid diethylester. Results of this study provide some alternatives to diversify the number of wine styles by safely conducting MLF in low-pH, cool-climate white musts with potential high alcohol content.

Influence of malolactic bacteria inoculation scenarios on the efficiency of the vinification process and the quality of grape wine from the Central European region

“…The final concentrations of ethanol obtained in the vinification with alcoholic fermentation only (AF) did not differ considerably from those obtained in the other variants of the process (COI, SEQI, and SPONT) ( Table 3). This result confirms the observations of other authors who have reported no disturbances to alcoholic fermentation when employing similar bacterial inoculation variants [1,14,19,30,39,43]. Although some authors have pointed to disturbances in alcoholic fermentation attributed to the activity of malolactic bacteria, these have concerned the viability of the yeast-a reduction in their growth dynamics and metabolic activity-with no significant influence on the final ethanol content in wines [7,34].…”

“…Tristezza et al [39] reported a significant reduction in volatile acidity (0.30-0.31 g/L) as a result of simultaneous yeast and bacteria inoculation, in comparison to sequential inoculation (0.49-0.51 g/L). A similar trend was noted by Knoll et al [19] in the vinification of cool-climate Riesling: for the four MLF inoculation timings tested (24 h after yeast inoculation and after 40, 60, and 100% of alcoholic fermentation completion), the concentration of acetic acid in the final wine increased from 0.61 to 0.77 g/L, respectively.…”

“…However, it must be emphasized that both the total acidity (9.38-12.14 g/L) and the malic acid concentration (6.54-9.5 g/L) were higher than other grapes presented in the literature (Table 2) [1,8,14,18,19,30,34,39,43]. …”

Effect of Oenococcus Oeni on Parameters of Oenological Polish Wines

“…Dla porównania, w hiszpańskich winach Tempranillo i Merlot stwierdzono obniżenie kwasowości po MLF, odpowiednio: z 3,99 do 3,03 ÷ 3,53 g/l oraz z 5,13 do 3,65 ÷ 4,23 g/l kwasu winowego w zależności od użytego szczepu O. oeni [5]. Z kolei w białych winach zimnego klimatu po MLF odnotowano istotne zmniejszenie kwasowości [16]. Powodem tak wysokiej kwasowości badanych win mogły być warunki pogodowe w czasie dojrzewania winogron.…”

“…Na zawartość polifenoli wpływ mają: odmiana winogron, stopień dojrzałości oraz nasłonecznienie w czasie dojrzewania owoców. Wina krajowe, z powodu krótkiego okresu wegetacyjnego i mniej sprzyjających warunków pogodowych, odznaczają się mniejszą zawartością polifenoli w porównaniu z winami pochodzącymi z krajów o cieplejszym klimacie [7,14,16].Powodem wzrostu ilości związków polifenolowych podczas odkwaszania mogła być również aktywność enzymatyczna bakterii oraz mała specyficzność metody. O. oeni wykazuje niewielką zdolność do syntezy lotnych związków fenolowych, jednak ma enzymy hydrolizujące polimery flawanoli, a także wykazuje aktywność β-glukozydazy.…”