Harvest Series 2017: Yeast NutritionJasha Karasek

Winemaking specialist Enartis USA

WEBINAR INFO

• 40 Minute presentation + 20 minute Q&A• Save Qs until end of presentation• Use chat box for audio/connection issues• Poll questions• Recording in progress• Exclusive coupon code at end of webinar• Please fill out our survey in follow-up email!

Overview

• Importance in winemaking• Yeast nutrition requirements• Nitrogen uptake • Nutrient application timing• Nutrients for aromas• Preventing sluggish ferments• Juice nutrient status

Why Do We Care?

• Sluggish/Stuck fermentation• H2S / Sulfide formation• Flavor/aroma development• Time constraints

Yeast Nutritional Requirements

Biocheminalfunction

Enological effect Addition

NITROGEN Protein synthesis- Stimulate yeast multiplication- Prevent H2S production- Stimulate aromas production

inoculation1/3 fermentation

STEROLS AND FATTY ACIDS

(Survival factors)

Components of yeast cell

membrane

- Maintain yeast membrane activity- Increase yeast resistance- Reduce off flavors production

1/3 fermentation

THIAMINE Co-enzyme- Stimulate yeast growth

Inoculation

Mg-Zn Co-enzyme - Maintain yeast metabolism active Inoculation

Yeast Nitrogen

inorganic Nitrogen organic

CHALLENGES

• Amino acid uptake in presence of ethanol is very limited

• High NH4+ limits Amino acid uptake in early fermentation

Nutrient addition timing

Cell #

Time

Brix

Added in Innoculation

Added at 1/3 Brix Drop

Organic

Nutrients

Complex nutrients/DAP

Organic Nutrients

AA content AA quality Thiamine Other Micronutrients

Sterols/ FattyAcids

High • Building cell mass

• Preservesvarietal expression

.15% High Moderate

Very High • Aromatic precursors

• Strong fermentation

.15% High Moderate

Thiamine

INFLUENCE ON YEAST GROWTH

0,00E+00

2,00E+07

4,00E+07

6,00E+07

8,00E+07

1,00E+08

1,20E+08

1,40E+08

1,60E+08

1,80E+08

2,00E+08

0 20 40 60 80 100

yeast (cell/m

l)

Time (hours)

With thiamine

Without thiamine

WARNING! THIAMINE CAN BE INACTIVATED BY SO2:

ADD 2-3 HOURS AFTER SULFITING

• Co-Enzyme: Allows pyruvic acid to be converted to Ethanol in fermentation

Boosting Fermentation Aromatics

Main factors influencing wine aromas:

• Varietal precursors

• Yeast strain

• Fermentation kinetics

• Amino acid content of juice

HOW IT WORKS

ESTERSCONCENTRATION

(mg/l)AROMA

2-phenylethyl acetate 0.01-4.5 Rose, honey

Isoamyl acetate 0.03-8.1 Banana, pear

Isobutyl acetate 0.01-0,8 Banana

Hexyl acetate 0-4.8 Ripe apple

Ethyl Butanoate 0.01-3 Flower, fruit

Ethyl caproate Traces-3.4 Apple

Alcohol Acetyl Transferase

AA - phenylalanine

Floral

2-phenylethyl acetateRose/Honey

Higher Alcohol 2-phenylethanol

NH3

CO

Acetyl-CoA

CoA

Nutriferm Arom Plus vs. DAP

Aroma Threshold (mg/L) DAP (mg/L)NUTRIFERM AROM

PLUS (mg/L)

Ethyl butyrate APPLE 0.125 0.39 0.64

Ethyl hexanoate

APPLE PEEL

0.062 0.75 1.06BERRIES

PINEAPPLE

Ethyl octanoate FRUIT 0.5 0.39 0.96

Ethyl decanoate GRAPE 0.2 0.11 0.16

Isoamyl alcoholWHISKY

30 248 322BANANA

2-phenylethanol ROSE

14 35.3 42.7

LILIAC

Yeast selection for Arom plus

For Nutriferm Arom plus, use high ester producing yeast

Nutrient addition timing

Cell #

Time

Brix

Added in Innoculation

Added at 1/3 Brix Drop

Organic

Nutrients

Complex nutrients/DAP

Mid Fermentation DAP addition

0

0,5

1

1,5

2

2,5

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7

NITROGEN

EFFECT OF NITROGEN ADDITION ONSUGAR TRANSPORT SPEED AT 1/3 FERMENTATION

(Salmon, 1989)

glu

cose tra

nsport

speed (

µm

ol xyl/h/g

)

Fermentation progression

CONTROL

NITROGEN ATHALF A.F.

Nutriferm Gradual Release

DAP+ (90%) , Gallic tannin, and Untoasted oak tannin

• Slowly releases NH4+ • Permeability dependent on [EtOH]• Complete dissolution of product • Eliminate multiple adds• Maximize AA uptake • Deliver NH4

+ slowly over course of fermentation• limit H2S production

Nutriferm Gradual Release

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10

Re

lea

se

d p

rod

uct %

days

Preventing Stuck/Sluggish Fermentations

Sterols Challenges:

• Yeast require fluid membrane cellular function

• Yeast require sterols to maintain membrane fluidity

• Yeast produce sterols with the aid of oxygen

• Low oxygen in fermentation environment inhibits sterol production

Long chain Fatty acids

EtOH

EtOH

EtOH

EtOH

EtOH

Complex Nutrients

Yeast cell walls rich in:

• Unsaturated long-chain fatty acids• Sterols• Prevents Stuck/sluggish ferments

Added to must at 1/2 sugar depletion with good YAN levels

Enriched Yeast hulls, DAP, cellulose

Added to must at 1/3 sugar depletion

• Provides sterols, long chain fatty acids• Vitamins• Essential micronutrients• Detoxifies must• Prevents stuck/sluggish fermentations

Yeast nutrition strategies

Nutriferm gradual release

1/3 Sugar depletion 1/2 Sugar depletion

or

Juice

Measuring Yeast Nutrient Status

YAN – Yeast Assimilable Nitrogen by Enzymatics

- Nitrogen from amino acids

- Nitrogen from NH4+

Brix level important:

1 Brix req. approx. 10 mg/L YAN

Total YAN required Dependent on Yeast strain, nutrient quality