"Light roast" vs "dark roast" bukan cuma warna. Ada chemistry + development time + flavor consequence yang fundamental berbeda. Panduan ini breakdown sistem roast level dan bagaimana mereka mempengaruhi brewing.

Sistem Pengukuran Roast

Warna Visual (Cepat tapi Tidak Presisi)

Light — coklat terang, biji permukaan kering (no oil)
Medium — coklat sedang, oil mulai mengkilap tipis
Medium-Dark — coklat tua, oil visible
Dark — nyaris hitam, oil membasahi biji

Agtron Scale (Objective Measurement)

Alat scanner warna Agtron M-Basic:

Agtron 85+ — Very Light / Cinnamon Roast
Agtron 75 — Light (City Roast)
Agtron 65 — Medium (Full City)
Agtron 55 — Medium-Dark (Full City+)
Agtron 45 — Dark (Vienna/French)
Agtron 25-35 — Very Dark (Italian/Espresso continental)

Specialty umumnya Agtron 55-85. Specialty TIDAK pakai Agtron <45 karena dark roast mask origin character.

Chemistry Roast Level

First Crack (~196-205°C)

Biji ekspansi, lepas uap + CO2, volume doble. Menandakan awal "drinkable coffee". Light roast biasanya develop 1-2 menit post-FC.

Second Crack (~224-230°C)

Oil migrate ke permukaan. Sel biji pecah fase kedua. Masuk teritori dark roast (Vienna, French, Italian). Specialty filter TIDAK lewat 2C.

Development Time Ratio (DTR)

DTR = (total roast time - FC time) / total time
Umum 18-25%
DTR tinggi (25%+) = flavor developed, acidity menurun
DTR rendah (15%-) = bright + under-developed (hati-hati "baked")

Flavor Profile per Level

Light Roast (Agtron 75-85)

Acidity: tinggi, bright, citrus/berry/floral
Body: ringan, tea-like
Sweetness: natural (bean sugar), delicate
Bitter: minimal
Origin character: maximal (fruity Ethiopia, winey Kenya, floral Gesha)
Brew method fit: pour-over (V60, Kalita, Origami), filter

Medium Roast (Agtron 55-75)

Acidity: sedang, apple/wine/orange
Body: medium
Sweetness: caramel development
Bitter: low-medium
Origin character: sedang (balance)
Brew method fit: semua metode (versatile)

Medium-Dark (Agtron 45-55)

Acidity: rendah
Body: tebal
Sweetness: chocolate, molasses, brown sugar
Bitter: sedang
Origin character: tertutup Maillard development
Brew method fit: espresso, moka pot, French press

Dark Roast (Agtron <45)

Acidity: very low
Body: heavy, oily mouthfeel
Sweetness: burnt sugar, carbon
Bitter: dominant
Origin character: hilang, semua "roasty"
Brew method fit: espresso continental, dengan susu
Note: umumnya bukan specialty preference

Pairing Roast × Brew Method

Brew	Light	Medium	Dark
V60 / Filter	✓✓	✓✓	×
AeroPress	✓	✓✓	✓
French Press	—	✓✓	✓
Moka Pot	—	✓	✓✓
Espresso	✓ (advanced)	✓✓	✓✓
Cold Brew	×	✓✓	✓
Tubruk / Vietnam	—	✓	✓✓
Milk drink	—	✓	✓✓

Kopi Indonesia

Arabica Gayo, Sumatra: umum medium-dark, wet-hulled karakter earthy
Arabica Kintamani: medium, washed, bright
Arabica Toraja: medium-dark, full body
Robusta Lampung / Sumatra: dark umum untuk chainstore; medium untuk specialty

Common Misconceptions

Dark roast lebih kuat kafein?

Myth. Kafein tahan panas, tidak terdegradasi signifikan oleh roasting. Per BERAT, light roast sedikit lebih tinggi (karena biji tidak kehilangan mass by volume). Per VOLUME scoop, dark lebih ringan jadi per-scoop kafein lebih rendah. Lihat panduan.

Light = "asam" = buruk?

Myth. Specialty light roast fruity acidity ≠ "sour stomach acid". Acidity ini compound organik yang bright dan menyenangkan. Kopi "sour stomach" biasanya karena over-ingestion atau lambung sensitif, bukan bean karakter.

Dark roast = "kopi asli"?

Myth cultural Indonesia. Dark roast bukan authentic, ini hasil industri kolonial + masking low-quality beans. Specialty coffee culture globally prefer light-medium untuk highlight character.

Rekomendasi Pemula

Mulai dengan medium roast Indonesia (Gayo, Kintamani, Toraja washed)
Brew V60 default ratio 1:16 rasakan character
Coba light roast setelah 2 minggu adaptasi — kalau feel "asam", masih normal
Dark roast hanya untuk milk drink atau traditional warkop preference

Sumber

Scott Rao — "The Coffee Roaster's Companion"
Rob Hoos — "Modulating the Flavor Profile of Coffee"
Specialty Coffee Association — Roasting Foundations course
Sweet Maria's — roast level visual guide