Specific Content of the Adaptation Between Drying Processes and Tea Seed Processing Stages

The adaptation between drying processes and tea seed processing stages is centered on "accurately matching drying parameters (temperature, time, air volume, and tempering method) based on the characteristics of tea seeds at different processing stages, subsequent process requirements, and quality objectives". This avoids tea seed quality degradation (such as oil oxidation and increased breakage rate) and reduced efficiency of subsequent processes (such as difficult pressing and insufficient oil yield) caused by mismatches between drying and processing stages. Below are the detailed adaptation schemes of drying processes for the entire tea seed processing cycle (post-harvest pretreatment → storage → pre-pressing → pre-deep processing), developed in conjunction with the physical properties of tea seeds and processing logic:

I. Core Adaptation Principles

Moisture Gradient Adaptation: Each processing stage corresponds to a unique "target safe moisture content", and the drying process must precisely control the moisture reduction range (to avoid over-drying or under-drying);

Quality Priority Adaptation: Low-temperature slow drying is adopted for heat-sensitive stages (such as seed-grade tea seeds and raw materials for deep processing), while balancing efficiency and quality for conventional processing stages;

Subsequent Process Adaptation: The physical state of dried tea seeds (hardness, breakage rate, fluidity) must match the next process (storage → anti-caking, pressing → easy oil extraction, deep processing → easy extraction).

II. Stage-Specific Drying Process Adaptation Schemes

Stage 1: Post-Harvest Pretreatment Stage (Core Objective: Rapid Moisture Reduction, Mold Prevention, and Laying the Foundation for Storage/Subsequent Processing)

Tea Seed Characteristics: Freshly harvested tea seeds (with shells) have a moisture content of 25%-35% (wet basis), featuring damp shells, easy clumping, high free moisture content, and susceptibility to mold and germination when stored at room temperature for 24 hours;

Subsequent Process Requirements: Dried tea seeds must have a certain fluidity, no mold, no shell cracking, and be easy for cleaning, grading, and storage;

Detailed Drying Process Adaptation:

Key Notes:

Prohibit high-temperature rapid drying (temperature >55℃): It will cause tea seed shell cracking, free oil seepage, and accelerated oxidation;

Cool dried tea seeds to ambient temperature ±5℃: Avoid dew condensation and moisture regain caused by directly placing high-temperature tea seeds into airtight containers (such as sacks and silos).

Stage 2: Storage Stage (Core Objective: Long-Term Safe Storage, Mold Prevention, Germination Prevention, and Oil Rancidity Prevention)

Tea Seed Characteristics: Pretreated tea seeds have a moisture content of 15%-20%, which needs to be further reduced to "long-term storage safe moisture content"; otherwise, during the storage period (3-6 months), nutrients are easily consumed due to respiration, and mold is prone to grow;

Subsequent Process Requirements: Tea seeds after storage must maintain intact shells, uniform moisture content (≤10%), no clumping, no peculiar smell, and can directly enter pressing or reprocessing after 出库;

Detailed Drying Process Adaptation:

Key Notes:

"Stepwise moisture reduction" is required for drying before storage: First reduce from 15%-20% to 12% (first stage, temperature 45℃), temper for 2 hours, then reduce to 8%-10% (second stage, temperature 40℃) to avoid shell cracking caused by one-time large-scale moisture reduction;

Dried tea seeds need to be "classified and cleaned": Remove broken grains and moldy grains (broken grains are prone to excessive moisture and are the main cause of mold during storage).

Stage 3: Pre-Pressing Stage (Core Objective: Optimize Pressing Efficiency, Improve Oil Yield, and Reduce Crude Oil Impurities)

Tea Seed Characteristics: Tea seeds after storage have a moisture content of 8%-10%, with hard shells and semi-solid internal oil; moisture and hardness need to be adjusted through drying to adapt to pressing processes (physical pressing/screw pressing);

Subsequent Process Requirements: Dried tea seeds must have "moderate hardness" (avoid excessive crushing during pressing leading to overly fine cake meal that clogs the oil press), uniform moisture content (±0.5%), and easy oil flow;

Detailed Drying Process Adaptation:

Key Notes:

Cool dried tea seeds to 30-35℃ before pressing: Direct pressing of high-temperature tea seeds will increase the acid value of crude oil (acid value increases by 0.3-0.5mg/g for every 10℃ increase);

Adapt to different pressing processes: Physical pressing (hydraulic) has stricter moisture requirements (6%-7%), while screw pressing can be appropriately relaxed to 7%-8%, which needs to be fine-tuned according to equipment type.

Stage 4: Pre-Deep Processing Stage (Core Objective: Protect Active Ingredients, Reduce Impurities, and Adapt to Extraction/Refining Processes)

Tea Seed Characteristics: Tea seeds used for deep processing (such as extracting tea seed oil, tea saponin, and tea polyphenols) need to maintain the integrity of oils and active ingredients to avoid structural damage caused by high temperatures;

Subsequent Process Requirements: Dried tea seeds must be free of oxidation and peculiar smell, have uniform moisture content (≤6%), and have good fluidity when crushed (adapting to extraction and refining equipment);

Detailed Drying Process Adaptation:

Key Notes:

Prohibit the use of odorous heat sources (such as coal and low-quality biomass): Odors from heat sources will be adsorbed on tea seeds, affecting the flavor (such as the aroma of tea seed oil) and purity of deep-processed products;

Seal and store after drying: Low-moisture tea seeds have strong hygroscopicity and must be immediately packaged in food-grade airtight containers to avoid moisture absorption from the air leading to quality degradation.

Special Stage: Seed-Grade Tea Seed Processing (Core Objective: Maintain Germination Rate and Adapt to Sowing Requirements)

Tea Seed Characteristics: Seed-grade tea seeds need to maintain embryo viability; high temperatures will cause embryo necrosis and a sharp drop in germination rate;

Detailed Drying Process Adaptation:

Hot air temperature: 35-40℃ (constant temperature throughout, maximum not exceeding 42℃);

Target moisture content: 10%-12% (excessive moisture is prone to mold, insufficient moisture causes embryo dehydration and death);

Drying method: Natural ventilation + low-temperature hot air assistance (avoid direct strong wind blowing on the embryo);

Tempering design: Stop and temper for 1 hour after every 2 hours of drying to reduce the internal moisture gradient of the embryo;

Key indicator: Germination rate after drying ≥85% (no germination rate requirement for conventional processed tea seeds).

III. Adaptation Effect Verification Indicators (Ensuring Matching Between Drying Processes and Processing Stages)

Moisture Indicators: Target moisture deviation ≤±0.3% (storage/deep processing stages), ≤±0.5% (pretreatment/pre-pressing stages);

Quality Indicators:

Conventional processing: Acid value ≤3mg/g (KOH), peroxide value ≤0.06g/100g, breakage rate ≤0.5%;

Deep processing: Tea polyphenol retention rate ≥90%, tea saponin extraction rate ≥85%;

Seed-grade: Germination rate ≥85%, embryo necrosis rate ≤5%;

Process Adaptation Indicators:

Storage: No mold after 3 months of storage, clumping rate ≤3%;

Pressing: Oil yield ≥28% (conventional tea seeds), crude oil impurity content ≤0.5%;

Deep processing: Extraction time shortened by 10%-15% (compared with unmatched drying processes).

IV. Common Adaptation Mistakes and Correction Schemes