Roasting for espresso

Espresso is a brewing method not a type of bean.

Espresso machines use high pressure and shorter brew times when compared to other brew methods like filter.

Thus beans that are tailored for espresso are roasted in special ways.

An espresso roast refers to coffee beans roasted specifically for espresso brewing, typically longer and hotter than filter roasts to increase body and decrease acidity. This longer roasting process makes the beans more soluble for extraction, while the darker color and oily surface develop richer, bolder flavors like chocolate and caramel. While labeled for espresso, these beans can also be used for other brewing methods. Though there are no hard rules, here are some ideas to keep in mind.

A huge number of espresso shots will be put into milk beverages.

So to cut through the milk the shots need to have more caramelized , chocolate and smoky notes for example. This will pair better with milk in comparison to lighter coffees that have more acidity.

Even if there is some bitterness from the darker roast, the sweetness in the milk should balance this.

Darker roasts because they are more porous are easier for the espresso machine, which uses very little water, to extract.

☕️ 1. Start with the Right Green Coffee

When buying, look for beans lots with:

• Medium natural acidity (so you don't need to roast too dark to bring out the acidity) and even if you roast to the start of second crack you will still have full mouthfeel , some body and sweetness.
• Dense, even beans
• Clean processing (washed or pulped natural)

Here are suggested espresso-friendly origins and varieties:

Origin	Varieties	Flavor Profile (Espresso)	Roast Target
Brazil (Minas Gerais, Cerrado, Sul de Minas)	Bourbon, Catuai, Mundo Novo	Chocolate, nutty, caramel, mild fruit — classic espresso base	Medium-dark (just past first crack)
Colombia (Huila, Antioquia)	Caturra, Castillo, Typica	Balanced, sweet, toffee and citrus hints — adds brightness and sweetness	Medium
Guatemala (Antigua, Huehuetenango)	Bourbon, Carivore Caturra, Typica	Cocoa, stone fruit, brown sugar — deep sweetness, great body	Medium
El Salvador / Nicaragua	Bourbon, Pacamara	Syrupy, chocolate, subtle fruit — great for single-origin espresso	Medium-dark
Ethiopia (Sidamo)	Heirloom	Floral, tea-like, fruity — good for modern “specialty” espresso	Light to medium (careful roast)
Sumatra (Lintong, Aceh)	Typica	Earthy, spicy, heavy body — perfect for blending	Medium-dark
India (Kaapi Royale, Plantation A) India (Monsoon Malabar)	Robusta or Arabica Robusta or Arabica	Deep crema, spice, cocoa bitterness Deep crema, spice, cocoa bitterness	Dark, small % in blend Dark, small % in blend

-

notes:

• Don't choose something like a Ethopian Yirgacheffe which is a great filter coffee. This bean is sour, fruity but acidic. To roast the acidity out of the bean you would have to go so dark that the coffee would loose sweetness and body.

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🔬 2. Suggested Blend Formulas

You can roast each origin separately, then blend post-roast to fine-tune balance.

💎 Classic Italian-style Espresso Blend

Component	Ratio	Roast	Role
Brazil Bourbon	50%	Medium-dark	Base sweetness & chocolate
Colombia Caturra	30%	Medium	Balance & mild acidity
India Robusta (Kaapi Royale)	20%	Dark	Crema & strength

→ Result: Thick crema, chocolate/caramel profile, low acidity, perfect with milk.

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🌸 Modern Specialty Espresso Blend

Component	Ratio	Roast	Role
Guatemala Bourbon	40%	Medium	Body & sweetness
Ethiopia Heirloom	40%	Medium-light	Fruity, floral top notes
Brazil Catuai	20%	Medium-dark	Base & balance

→ Result: More aromatic, juicy espresso with higher sweetness and layered flavor.

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🔥 3. Roast Strategy Tips for Espresso

Espresso extraction highlights both sweetness and roast flaws — so aim for:

1. Even development: 20–25% development time ratio after first crack.

2. No tipping/scorching: Keep charge temps moderate.

3. You want a somewhat flatter curve to increase development, but you don't necessarily want to change your drop temperature. So, using the same bean you might roast 10-30% longer for an espresso roast than a drip roast.

4. Roast depth:

   • Light → brighter, acidic espresso (good for fruity beans).

   • Medium → sweet, balanced espresso.

   • Medium-dark → chocolatey, creamy, traditional espresso.

5. Rest time: Always rest 5–10 days after roasting before pulling espresso — CO₂ affects extraction and crema.

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⚙️ 4. Buying Tips

When shopping for green beans:

• Check density (high-density = more flexible in roast).

• Avoid very bright African coffees for your first espresso roasts.

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🧾 5. Sample Roast Plan (for a Brazilian Bourbon)

Roaster: 1 kg drum

• Charge: 195°C

• Dry end: 5:00

• First crack: 9:00 (198–200°C)

• Drop: 11:00 (208–210°C)

• Development ratio: ~20%
  → Medium-dark roast, chocolate, almond, caramel.

• --------------------------------------------------------------------

• Using a Behmor 2020 ... my plan

• the Behmor 2020SR is a solid home drum roaster for espresso roasting. It’s gentle, has good thermal momentum, and allows for repeatable profiles once you learn how to manage its heat curves.

• ⚙️ 1. Understanding the Behmor for Espresso

  The Behmor 2020 uses preset power levels (P1–P5) and manual overrides rather than full PID control.
  Key Behmor traits to keep in mind:

  • Slower heat response → favors medium to medium-dark roasts.

  • Lower convective airflow → easier to develop syrupy, chocolatey espresso beans.

  • Best batch size: 250–300 g (for consistent drum temps and airflow).

  ---

  ☕️ 2. Espresso Bean Strategy for the Behmor

  Since the Behmor naturally encourages smooth, full-bodied roasts, choose low-acid, dense beans. Perfect for:

  • Brazil Bourbon or Catuai (base)

  • Colombia Caturra or Castillo (sweetness)

  • India Kaapi Royale Robusta (optional crema & strength)

  • Optional modern touch: small % of Ethiopia Guji or Sidamo Heirloom

  ---

  🧪 3. Recommended Blend (Behmor-Optimized)

  Classic Balanced Espresso (beginner-friendly)

  Component	%	Purpose
  Brazil Natural Bourbon (Minas Gerais)	50%	Chocolate base
  Colombia Washed Caturra (Huila)	30%	Sweetness & mild acidity
  India Robusta Kaapi Royale	20%	Crema & depth

  Optional tweak: Replace Robusta with 10% Sumatra Typica for more earthy complexity and lower caffeine.

  ---

  Modern Specialty Espresso (fruitier)

  Component	%	Purpose
  Brazil Catuai (Natural)	40%	Chocolate base
  Guatemala Bourbon (Antigua)	40%	Brown sugar & fruit balance
  Ethiopia Sidamo Heirloom (Washed)	20%	Floral top notes

  → Use a slightly lighter roast to preserve aromatics.

  ---

  🔥 4. Behmor Roast Profile (Medium–Dark Espresso)

  Here’s a tested Behmor 2020 roast plan (300 g batch) for espresso balance:

  Stage	Time (min)	Target Temp (approx.)	Power	Notes
  Drying	0–5:00	~150 °C	P5	Even yellowing; beans still grassy.
  Maillard	5:00–9:00	150–190 °C	P4	Light brown, caramel aromas.
  1st Crack Start	~9:30–10:00	~196 °C	P3	Listen carefully — Behmor muffles cracks.
  Development	10:00–11:30	~208–210 °C	P3 or P2	1.5–2 min after 1st crack start.
  Drop/Cool	~11:30	—	Cool immediately	Use the Behmor’s cooling cycle + door open.

  Development Ratio: ~20% of total roast time.
  → You’ll get a medium-dark roast, sweet with low acidity and syrupy body. Perfect for espresso.

  ---

  🧊 5. Post-Roast Tips

  • Rest: 5–10 days minimum (7 is ideal) before pulling espresso.

  • Storage: Airtight, dark, one-way valve bag.

  • Dial-in guidance:

  • Dose: 18 g in / 36 g out / 28–32 s (9 bar, 93 °C)

  • Grind slightly finer than for medium roasts.

  • ---------------------------------------------------------------------------------------------------------
    Coffee index. Click here :
    
    
    https://djjondent.blogspot.com/2024/03/coffee.html

Coffee bean grading systems

Coffee bean grading systems are methods used to evaluate and classify coffee beans based on their quality, size, origin, and defects. These systems vary by country and are often tied to national standards or export regulations. Here's a detailed overview of the main grading approaches used globally:

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☕ 1. By Bean Size (Screen Size Grading)

• Used in: Many countries including Kenya, Colombia, and Central American nations.

• Basis: Bean sizes are graded by passing green coffee beans through a series of standardized mesh screens, where holes are measured in 1/64ths of an inch. A size 18 screen represents 18/64ths of an inch. The beans are separated by size to ensure consistent roasting, as larger beans are often denser and take longer to roast, while smaller beans might burn

• Screen System (8–20): Beans are sorted, and the percentage remaining on each screen is recorded.

• Key Grading Methods & Sizes:  Eg:

  Grade /screen 18 or "AA": Considered large/premium, these are 18/64 inches or larger.
  Grade / screen 15 or "A"/"AB": Slightly smaller beans.

• • Screen 16 = 16/64 inch (medium)

  • Screen 14 = 14/64 inch (small)

• Typical Labels:

  • AA: Very large (Screen 18+)

  • AB: Medium-large (Screen 16–17)

  • C: Smaller (Screen 14–15)

  • Peaberry (PB): A natural mutation where only one round bean grows in a cherry instead of two.
    
    
  • Regional Differences: In the Americas, sizes can be grouped as high as Superior (size 17+) and as low as Terceras.

👉 Larger beans don’t necessarily mean better flavor, but they often roast more evenly.

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🌍 2. By Altitude or Growing Region

• Used in: Latin America (especially Central America).

• Basis: Higher altitudes tend to produce denser, harder beans with more complex flavors.

• Example (for Arabica beans):

  • Strictly Hard Bean (SHB) / Strictly High Grown (SHG): Grown above 1,200–1,400 m (4,000–4,600 ft)

  • Hard Bean (HB): 900–1,200 m

  • Medium / Low Grown: Below 900 m

• Countries using this: Guatemala, Honduras, Costa Rica, Panama, etc.

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🧾 3. By Defect Count (Quality / Cleanliness Grading)

• Used in: Ethiopia, Brazil, Colombia, and many others.

• Basis: Number and type of defects (broken beans, black beans, insect damage, etc.) in a 300–350g sample.

• Example:

  • Specialty Grade: 0–3 defects per 350g; excellent uniformity and cup quality.

  • Premium Grade: 4–8 defects.

  • Exchange Grade: 9–23 defects.

  • Below Standard: More than 23 defects.

• System reference: Specialty Coffee Association (SCA) cupping standards.

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🌱 4. By Cup Quality (SCA Cupping Score)

• Used globally in specialty coffee markets.

• Basis: Sensory evaluation by certified Q-graders.

• Scoring system (0–100 points):

  • 90–100: Outstanding (Rare)

  • 85–89.99: Excellent (Specialty)

  • 80–84.99: Very Good (Specialty)

  • <80: Below specialty grade

• Assessed attributes: Aroma, flavor, acidity, body, balance, sweetness, uniformity, aftertaste, and defects.

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🇧🇷 5. By Country-Specific Systems

Each coffee-producing country often has its own grading terminology and criteria. Examples:

Brazil:

• Uses NY (New York) grading and screen size.

• Grades like NY 2/3, NY 4/5 — lower numbers mean fewer defects.

Colombia:

• Grades by size and density: Supremo (screen 17/18), Excelso (screen 14–16).

Ethiopia:

• Grades 1 to 9 based on defects and cup quality:

  • Grades 1–2: Washed, specialty-grade

  • Grades 3–5: Natural or lower quality

  • Grades 6–9: Commercial/lower grades

Kenya:

• Grades mainly by screen size:

  • AA: Screen (17-18)

  • AB: Screen 15–16

  • C : small, thin, or slightly misshapen Arabica beans that fall below the size of premium AB grades, typically fitting screens 12–14. They can still produce high-quality, flavorful cups, notes.

  • PB (Peaberry): A natural mutation where only one bean develops inside the cherry rather than two. Peaberries are smaller (screen size 12+) and rounder, often prized for their dense, vibrant cup profiles.

  • TT : Higher grade than T (involves 'ears" which are hollowed out shells) but smaller than C.

  • T (T=Tea grade): Smaller or broken beans

  • E : Elephant. Malformed, oversized.

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🧡 Summary Table

Method	Focus	Example Grades	Typical Use
Size	Physical bean diameter	AA, AB, C	Kenya, Colombia
Altitude	Elevation/density	SHB, HB	Central America
Defect Count	Cleanliness/quality	NY 2/3, Grade 1	Ethiopia, Brazil
Cup Score	Sensory attributes	80+, 85+, etc.	Specialty coffee
National Standards	Country-specific	Supremo, Excelso, etc.	Colombia, Kenya

Rancilio Silvia - history

 The Rancilio Silvia is a well-regarded espresso machine known for its durability and performance. Over the years, Rancilio has released several versions and updates to this model. Here's a summary of the different versions (though officially Rancilio doesn't recognise these versions):

Rancilio Silvia V1 (Original):

Introduced in  1997.

Featured a basic design with a brass boiler & steam wand. The single 300ml boiler is used for both brewing and steaming. There is a small 2L water tank which feeds into the boiler. Uses a Ulka vibration pump.

The drip tray is a simple square design.

The logo of V1 has the words Silvia

Rancilio Silvia V2:

Introduced in 2000.

Improvements over the original model included a more durable stainless steel casing, better temperature stability, and enhanced ergonomics.

New drip tray

Logo has changed 

there were two OPV models.

Early: fixed OPV

Later: adjustable OPV

Both V1 & V2 used this steam knob

Rancilio Silvia V3:

Introduced around 2008.

Added improvements such as a redesigned steam wand, a more refined boiler temperature control, and a more user-friendly interface.

New steam valve knob. Partially chrome plated

New portafilter handle design.

New steam wand and steam nozzle.

Adjustable OPV

Brass boiler with a built in heating element.

Thus if you burn it up, you'll need to replace the whole boiler.

Rancilio Silvia V4:

2013.

The copper heating element was redesigned.

In the old models, the element was fixed.

There was now a removable element that screws from the inside of the brass boiler.

Rancilio Silvia V5:

2016.

Different lights on the on/off switch

They use LEDs.

Insulated boiler.

The heating element switches off after 30 mins

(to comply with new EU regulations).

Rancilio Silva V6 (E or M versions)

2020

Model No : HSD-SILVIA

Heating element :1100 W

Brass group head with Black group-head ring

2 L tank, 300ml insulated brass boiler

New screw in stainless steel element.

Version E - cut off timer

Version M - no cut off

Rancilio Silvia Pro:

Introduced in 2020.

This is a significant upgrade from previous models, featuring dual boilers (one for brewing and one for steaming), a built-in PID controller, and improved controls for a more professional-level performance.

These versions showcase the evolution of the Silvia over the years, with each iteration bringing enhancements in terms of build quality, temperature control, and user experience

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Coffee index. Click here :

https://djjondent.blogspot.com/2024/03/coffee.html

Gaggiuino -part 5 - wiring

This is part five of my Gaggiuino project.

Basically this adds a microcontroller to a relatively cheap coffee machine.

The earlier parts are here:

   Part 1 Gaggiuino Build Log with Workflow intro

   Part 2 Gaggiuino V3 - Build Log Notes - switches, PCB

   Part 3 Gaggiunio mod - The original Classic Pro - How it works

   Part 4 Gaggiuino - boot first time 

At this point I'm just breaking down the wiring and reading the schematic.

I often find I absorb info better if I write things down. Thus this blog.

And hopefully, it will help someone else doing this awesome project.

I am not part of the Gaggiuino development team so there may be mistakes here.

Do let me know if you find any. 

I have a 240 V Gaggia classic pro evo

And I'm using an official PCB from Peak in HK

I bought the kit with lots of parts to get this job done (hopefully with little fuss).

Though, you will need more cables, basic soldering skills & some patience.

Peak Coffee:

https://www.peakcoffee.cc/product/gaggiuino-v3-kit-set-gaggia-classic-pro/

The official project page is here:

https://gaggiuino.github.io/#/?id=home

The discord page is also useful:

https://gaggiuino.github.io/#/community/community-media

There are two important pics you need to digest to wire things up.

The first time I saw the pic below I was at a loss to see where things started or ended.

I'm familiar with electronics schematics, but the mix with hardware is new for me.

But its actually not too bad once you study it, compare to the schemo and work out what the labels mean.

Remember you are playing around with high voltage (240VAC), low voltage DC and hot pressurised water.

So be very careful.

If you've got a different machine, things will be a bit different, but hopefully not by too much.

The code goes something like this :

G = ground

3WV = 3 way valve

the 3 way valve has 3 terminals.

3WV N

3WV L

3WV G

Socket N = 240V power Neutral socket

Socket G = 240V power Ground socket

Socket L = 240V power Line socket

The brass 57 solenoid has 3 flat spade connectors

G = Gnd

L = Line

N (blue) = neutral

keep in mind that there is a difference between high voltage & low voltage cables

(HV use Crimped 6.3mm Terminal Connectors, 30-50cm AWG 22 cables )

Here is the schematic. Try to unite this in your mind with the pic above.

.......................................

I think I'll start with the 240v socket
(these are the pink boxes).

These connect to Neutral, Line & Gnd.

Socket N = 240V power neutral socket (blue in the schematic)

Socket G = 240 power ground socket

Socket L = 240 line socket

These need to be the thickest gauge wire as they are carrying the highest current

-------------------------------------------------------

The Solenoid

The brass 57 solenoid has 3 flat spade connectors

Its also know as the 3 way valve in the schematic.

3WV = 3 way valve

the 3 way valve has 3 terminals.

3WV N = neutral (blue)

3WV L = line (yellow)

3WV G = gnd

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these yellow boxed ends connect with the PCB

3-out ( to 3WV L)

P-out (to Pump L)

L-in (to the SSR)

N-in (to the pump fuse, pump N, etc)

all connect the PCB to the  outside world.

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The vibratory pump

It looks like it has just 2 terminals (Pump Fuse to Pump N 

& Pump L).

These connect to N  & P on the PCB.

---------------------------------------------

grounding wires

All green wires.....   start at the 240V power socket (socket G) on the right

and work left  (frame - 3 way valve - boiler ) to end at the cup warming plate on the extreme left.

-----------------

The SSR (Solid state relay)

A solid state relay (SSR) is an electronic switching device that switches on or off when an external voltage (AC or DC) is applied across its control terminals. They serve the same function as an electromechanical relay, but solid-state electronics contain no moving parts and have a longer operational lifetime.

It has two sides.

A high voltage AC side and a low voltage DC side.

The AC side connects to the coffee heating elements. 

The DC side connects to the PCB.

It basically translates between the two.

Both sides are isolated (even though they can communicate with each other) using LEDs and phototransistors.

What the SSR does is listen to commands from the microcontroller. 

If the microcontroller sends low voltage digital info to the SSR (say

to heat up the water), the SSR will carry out the command on the high voltage AC end.

It looks like the left AC out from the SSR 

connects to the thermofuse, 

or the resettable fuse 

& one heating element

I don't think you connect it to both.

+ Gaggia Classic Evo Pro - Modding with arduino - Gaggiuino

   Part 1 Gaggiuino Build Log with Workflow intro

   Part 2 Gaggiuino V3 - Build Log Notes - switches, PCB

   Part 3 Gaggiunio mod - The original Classic Pro - How it works

   Part 4 Gaggiuino - boot first time 

   Part 6 Gaggiuino boiler & pump removal

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Coffee index. Click here :

https://djjondent.blogspot.com/2024/03/coffee.html

RIO

 RIO

21-7-26

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ASX:RIO (Rio Tinto Limited) has maintained robust profitability and a highly conservative balance sheet over the last five years, though peak profits and Return on Equity (ROE) from the 2021 commodity boom have normalized. The company consistently generates massive cash flow and supports its share price with strong dividend payouts. [1, 2, 3, 4, 5]

A look at the key metrics over this period highlights these financial trends:

5-Year Financial Metrics

Profitability: Net profit has remained strong but has steadily normalized from its historical 2021 peak. For recent years, net profit after tax has sat around the \(\$10 \text{ billion}\) to \(\$15 \text{ billion}\) mark, compared to the massive \(\$21 \text{ billion}\) peak in 2021. The net profit margin has hovered around 17% to 20%. [1, 2, 3, 4, 5]
Return on Equity (ROE): Due to the cooling of peak iron ore prices, the 5-year average ROE sits at 24.1%, but it has trended down more recently. The trailing twelve months (TTM) ROE is approximately 16.4%. [1]
Debt Levels: The company has managed its long-term debt conservatively over the last 5 years, maintaining a debt-to-equity ratio of roughly 33% to 35%. Net debt has been remarkably low, often standing well below annual free cash flow, giving the company massive headroom to fund its capital pipeline. [1, 2, 3, 4]

Shareholder Value and Dividends

Rio Tinto generally operates with a dividend payout ratio of 60% of underlying earnings, returning billions to shareholders while continuing to advance major growth projects like the Oyu Tolgoi copper mine expansion in Mongolia

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Over the last 10 years, Rio Tinto Ltd (ASX: RIO) has traded at a mean historical P/E ratio of 10.44x, with a 10-year median of 12.25x. As a major cyclical mining stock, its price-to-earnings ratio moves dramatically based on global iron ore commodity pricing cycles. During this decade, its Trailing Twelve Months (TTM) P/E ratio has fluctuated between a minimum low of 4.89x and a maximum high of 21.82x. [1, 2, 3]

Track Annual P/E Ratio Closures

The table below outlines the P/E ratio ranges and year-end metrics recorded for Rio Tinto over the past decade: [1, 2, 3, 4, 5]

Year	Year-End P/E Ratio (Approx.)	Market/Commodity Context
Current (July 2026)	17.84x	Iron ore stabilization; stock trading roughly 46% above its 10-year historical median.
2025	14.4x – 17.9x	Commodity corrections offset by operational efficiencies and volume recovery.
2024	7.75x – 9.1x	Moderating demand from China cooled earnings from prior cyclical peaks.
2023	10.6x – 13.7x	Post-pandemic volatility; higher operational input and energy costs squeezed margins.
2022	7.69x – 7.8x	Drop from peak iron ore values normalized the valuation multi-year floor.
2021	5.5x	Record commodity prices pushed earnings to historic highs, resulting in a compressed, low P/E ratio.
2020	14.9x	Pandemic infrastructure spend fueled rapid revenue surges ahead of equity repricing.
2019	11.2x	Stable mid-cycle iron ore returns following structural supply deficits out of Brazil.
2018	9.8x	Sub-10x value range driven by aggressive capital management and high dividend pay-outs.
2017	13.4x	Global synchronized economic upswing boosted broad resource and mining multi-nationals.
2016	15.1x	Cyclical exit from the 2015 commodities rout; severely depressed trailing earnings inflated the ratio.

Evaluate Long-Term Trends

Cyclical Inversion: When iron ore prices spike, Rio's earnings surge exponentially faster than its share price, leading to a low P/E ratio (e.g., 5.5x in 2021). Conversely, when earnings drop, the P/E ratio artificially inflates. [1, 2]
Historical Average: Long-term investors look to the 10.44x mean as a baseline gauge for normalized valuation. [1]
Current Standing: The mid-2026 P/E ratio of 17.84x indicates the stock is currently trading at a premium compared to its broader 10-year historical track record.

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