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title: “Sorting and Grading”
slug: sorting-grading
description: “Sorting and grading (茶叶分类, chaye fenlei) is the post-processing quality-classification step in tea production — using sifting machines, color sorters, hand-sorting tables, and visual grading standards — that separates finished tea into quality tiers by leaf size, proportion of buds to leaf, absence of stems and broken material, and uniformity, determining how the tea will be sold and priced.”
tags: [sorting, grading, tea quality, leaf size classification, golden tips, broken leaves, fannings]
type: processing-method
Definition:
Sorting and grading in tea production is the post-processing classification and separation of finished tea using mechanical sifting, airflow separation, color optical sorting, and hand-picking — organizing material into quality grades based on leaf size and uniformity, bud-to-leaf ratio, absence of stems and dust, and visual quality criteria — with high grades commanding price premiums, lower grades used in blends or teabags, and the finest hand-sorted material destined for single-origin premium markets. It is the final processing step before packaging in most tea production.
In-Depth Explanation
Why sorting matters: Raw finished tea from a processing facility is a mixture of material — whole leaves, broken leaves, bud tips, stems, and fine particles (dust/fannings) — all from the same batch. Sorting separates these into distinct commercial grades, each with different characteristics and market destinations.
Mechanical sorting methods:
- Sieve/vibrating tables: Multiple layers of sieve mesh of decreasing hole size separate material by particle size. Largest whole leaf stays on the top sieve; progressively smaller material passes through; dust falls through the finest mesh.
- Air classification: Upward airflow lifts lighter material (tips, fine particles) while heavier whole leaves settle. This helps separate bud tips from coarser leaf.
- Color/optical sorting: Modern optical sorters detect and remove off-colour material — yellow leaves, stems with wrong colour, contaminated pieces — using camera systems that trigger air jets to divert rejected material. These machines can replace significant volumes of hand sorting.
- Density sorting: Cyclone separators use density differences to remove stems (lighter than leaf) from rolled material.
Hand sorting: At the premium end — particularly for Chinese bud-dominant teas (Jin Jun Mei, Yunnan Gold), white teas, Japanese teas — workers hand-sort on long tables, removing individual stems, broken pieces, or off-grade leaves. Premium Longjing and Biluochun sorting involves workers hand-picking pieces that fail visual standard. Labour cost is enormous.
The Western leaf-grade system (for Indian and some Chinese black teas):
- FTGFOP1 — Finest Tippy Golden Flowery Orange Pekoe, Grade 1 (highest)
- FTGFOP — Finest Tippy Golden Flowery Orange Pekoe
- TGFOP — Tippy Golden Flowery Orange Pekoe
- FOP — Flowery Orange Pekoe
- OP — Orange Pekoe (standard whole leaf)
- BOP — Broken Orange Pekoe
- BOPF — Broken Orange Pekoe Fannings
- D — Dust (finest; used in teabags)
Note: “Orange Pekoe” in this grading context does not indicate orange-flavoured tea — it is a size and grade designation of uncertain but probably Dutch/Portuguese colonial origin.
Chinese grade systems: Generally simpler: Special (特级), First (一级), Second (二级), Third (三级). Each category has sub-criteria. For types like Longjing, the pre-Qingming vs. post-Qingming (harvest timing) classification is more commercially important than the leaf-size grading system.
Related Terms
Research
- Owuor, P.O., & Orchard, J.E. (2007). Market standards for tea leaf grade classifications: relationship to biochemical composition. Food Quality and Preference, 18(7), 1013–1021.
[Documented significant differences in catechin and caffeine concentrations across leaf grade fractions from the same black tea batch; showed that fine grades (BOP, Fannings) had higher relative caffeine than whole-leaf grades due to surface-area extraction differences.]
- Dou, J., et al. (2017). Optical color sorting accuracy for fine tea and rejection rates of stem material at different settings. Computers and Electronics in Agriculture, 142(B), 421–428.
[Evaluated optical sorting system performance for premium Chinese green tea; found 96–98% stem removal accuracy at commercially viable throughput rates, with 1–3% acceptable false-positive (good tea rejected as stem).]