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Is complex nutrition more advantageous than mineral nitrogen for the fermentative capacities of S. cerevisiae?

FERMENTIS

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Oxidative stability of white wines : state of the art and enological tools to improve it.

Module organized in collaboration with Fermentis

Fermentis
Bely

Marina BELY,
Université de Bordeaux (Francia)

Rollero

Stéphanie ROLLERO,
Fermentis by Lesaffre (Francia)

During alcoholic fermentation, nitrogen is one of essential nutrient for yeast as it plays a key role in sugar transport and biosynthesis of and wine aromatic compounds (thiols, esters, higher alcohols).

The main issue of a lack in yeast assimilable nitrogen (YAN) in winemaking is sluggish or stuck fermentations promoting the growth of alteration species and leads to economic losses. However, correcting this nitrogen deficiency is sometimes not enough to restore proper fermentation performance. This suggests the existence of other nutritional shortages.

The aim of this work was to study the impact of the timing and the nature of nutrient addition (mineral nitrogen, 100 % yeast derivative or mixed complete (mineral nitrogen & yeast derivative) on alcoholic fermentation.

First, 16 commercial strains were inoculated in Sauvignon blanc grape must deficient in YAN (110 mgN/L) and with reducing sugars concentration adjusted to 240 g/L (potential alcohol content of 14.3 %vol.). Fermentation kinetics of strains were then classified in 3 groups: stuck, sluggish or complete alcoholic fermentations. New experiments were carried on in the same grape must supplemented in YAN with ammonium (mineral) or yeast derivatives products (100% organic or mixed) to get 200 mgN/L. Nutrient additions were made at the beginning of alcoholic fermentation (single addition) or in two additions (50% at the beginning + 50% at the middle of alcoholic fermentation). Our results show that supplementation with mixed nutrients is more beneficial for fermentation performance than mineral nitrogen alone. ractionated addition also seems to have a greater impact than single addition. This study highlights the need to think about yeast nutrition from a holistic perspective (nitrogen and lipid addition, timing of addition).

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