Objective: To allow beans to develop their dark brown/black colour and stimulate enzyme activity to produce vanillin compounds.

Sweating Process

1. Immediately store the blanched beans in the ‘sweatbox;’ an esky or suitable insulated storage container

   • Store the beans and maintain warmth throughout.

   • Ensure the temperature does not drop below 22 degrees)

   • The ideal temperature is 45-65°C with 80-90% humidity.

   • Keep the beans in small bundles to retain heat evenly. (1 kg lots works well)

2. Daily Monitoring:

   • Inspect beans every morning and check for excess moisture build-up.

   • Beans should be warm, flexible, and slightly damp.

   • Gently massage the bags to ensure all beans get sufficient heat.

3. Duration:

   • Sweating requires at least 2 days for small beans, and typically no more than 4 days for large beans

   • Typically a bag of mixed sized beans will sweat for 4 days as a rule.

Note: If there are beans that have not darkened, continue sweating the select beans overnight until a morning inspection shows a darkened colour throughout (usually in the thicker/larger beans) This may occur infrequently yet is worth attention.

What is the science behind this?

Thermal Conditioning Phase in Vanilla Processing: The Sweating Methodology

Biochemical and Physical Parameters of the Post-Blanching Fermentation Process

The "sweating" phase constitutes a critical intermediate thermal conditioning process in vanilla curing, occurring subsequent to blanching and preceding desiccation. This procedure involves the strategic elevation of pod temperature within controlled humidity parameters to initiate specific enzymatic and microbial transformations.

Methodological Implementation

The process demonstrates significant regional variation but generally encompasses:

1. Thermal encapsulation: Freshly blanched pods are transferred to insulated containers (traditionally wooden boxes lined with absorbent material) or wrapped in insulating textiles (wool blankets, cotton fabric layers)

2. Solar exposure: Wrapped/contained pods undergo controlled exposure to solar radiation, achieving internal temperatures of 45-55°C while maintaining relative humidity levels of 85-95%

3. Nocturnal retention: Thermal energy is conserved through continued insulation during non-solar periods to maintain metabolic activity

4. Duration parameters: The cycle is repeated for 7-14 days with daily material rotation to ensure homogeneous exposure

Biochemical Transformations

This thermal conditioning facilitates several critical processes:

1. Glucovanillin hydrolysis: Activation of β-glucosidase enzymes that cleave the glucosidic bond in vanillin β-D-glucoside, liberating free vanillin

2. Microbial succession: Controlled proliferation of specific microbial communities (predominantly lactic acid bacteria and non-Saccharomyces yeasts) that contribute secondary metabolites to the aromatic profile

3. Phenolic polymerization: Initiation of controlled oxidative reactions forming complex polyphenolic compounds that contribute to colour development and flavor stability

4. Tissue structural modification: Progressive cellular breakdown facilitating subsequent moisture removal during drying phases

5. Proteolytic activity: Limited protein hydrolysis generating specific amino compounds that serve as precursors for Maillard reaction products

Sensory Development Indicators

Properly executed sweating processes manifest observable transformations:

1. Chromatic evolution: Progression from bright green to dark brown/black coloration

2. Textural transformation: Development of characteristic suppleness and pliability

3. Aromatic development: Initial emergence of vanilla notes replacing vegetal characteristics

4. Surface crystallisation: Preliminary appearance of vanillin crystals ("frost") on pod surfaces

Regional Methodological Variations

Significant procedural differences exist between production regions:

1. Madagascar/Bourbon methodology: Extended sweating (10-14 days) under higher temperature conditions with minimal daily handling

2. Mexican process: Moderate duration (7-10 days) with alternating sun exposure and insulated rest periods

3. Tahitian approach: Shorter sweating phase (5-7 days) at lower temperatures to preserve specific floral notes characteristic of Vanilla tahitensis

The sweating phase represents perhaps the most crucial period for flavour development, with inadequate implementation commonly resulting in incomplete glucovanillin hydrolysis, insufficient aromatic development, and susceptibility to fungal contamination in subsequent processing stages. Precision in temperature and humidity control during this phase demonstrates significant correlation with final vanillin concentration and overall organoleptic quality.