Hello everyone,
I’m Andy, a tea enthusiast.
With advancements in technology,
let’s explore the relationship between machines and tea quality today.
▶ Can Machines Replace Tea Quality Testing?
Not with current technology.
▶ What is Tea Quality?
Tea quality goes beyond food safety standards
such as moisture content, pesticide residue, foreign matter, and bacterial counts.
Sensory evaluation remains the primary assessment method.
High quality means "delicious tea."
▶ How is Tea Quality Traditionally Tested?
Traditionally, tea is assessed in a suitable space using standardized equipment.
Tea Evaluation Tools
Based on ISO3103, evaluation involves:
• 3g of tea
• 6 minutes of brewing time
• 150ml of water
Tea Evaluation Rooms
Guidelines from the Tea Research and Extension Station recommend:
• North-facing natural lighting, evenly distributed without direct exposure.
• Avoid early or late sunlight.
• No reflective or vibrant colors, with predominantly white spaces and black countertops.
• Ambient temperature: 22–24°C; Humidity: 45–55%.
• Odor-free environment, away from restrooms.
In cases of insufficient sunlight, fluorescent or LED lights can supplement.
Ensure high color rendering (CRI > 95) to avoid issues like “metamerism,”
where tea quality appears inconsistent under different light sources.
▶ What Machines Can Be Used for Tea Quality Testing?
Non-Sensory Testing
• Moisture Content: Moisture analyzers.
• Pesticide Residue: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) and Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS).
• Foreign Matter: Color sorters, metal detectors.
• Bacterial Count: Total bacterial count quick test plates.
Sensory Testing
• Near-Infrared Spectroscopy (NIRS)
• LC-MS/MS
• GC-MS/MS
• Electronic Nose
• Electronic Tongue
These devices detect chemical signals through principles
like light scattering and reflection (NIRS),
molecular mass analysis (LC-MS/MS, GC-MS/MS),
conductivity (electronic tongue),
and resistance changes (electronic nose).
Standard references are essential for accurate results,
which are typically expressed as specific chemical molecules.
▶ What Are Standard References for Tea Quality Testing?
For LC-MS/MS and GC-MS/MS,
pure substances such as catechins, sugars, amino acids,
caffeine, and fatty acids serve as standard references.
While precise, this method is time-consuming and expensive.
For NIRS, a standard curve is required.
▶ Challenges in Establishing an Oolong Tea Standard Curve
Creating a standard curve is costly and time-intensive.
The first hurdle is defining oxidation levels for oolong tea.
Once defined,
at least 100 samples must undergo LC-MS/MS or GC-MS/MS testing to
measure catechins, sugars, amino acids, caffeine, and fatty acids.
• Cost per test: NT$2,000.
• Five compounds × 100 samples: NT$1,000,000.
This is a conservative estimate,
as real-world costs are often higher.
Once established, NIRS becomes a quick and economical method for testing.
This technology is already widely used in the food industry, such as in animal feed.
▶ Can Machine Data Translate to Delicious Tea?
Theoretically:
• Low catechins (astringent) and caffeine (bitter).
• High sugars (sweet) and amino acids (umami).
In practice:
A personal experiment showed delicious tea with
high catechin and caffeine levels but low sugars and amino acids.
After discussion,
this result mirrors the effect of adding salt to a bland watermelon to enhance its sweetness.
Such sensory experiences involve complex multifactorial statistical analysis that single chemical molecules cannot define.
Perhaps "complexity" is the true key to deliciousness.
Thank you for reading.
I hope this was helpful,
and I look forward to sharing more with you next time.
#yoshantea #taiwantea #dongdingtea #oolongtea #teafactory #FSSC22000 #safetea #teatesting #sensoryevaluation #ISO3103 #LCMSMS #GCMSMS #NIRS #electronicnose #electronictongue #moistureanalyzer #totalbacterialcount #colorsorter #metaldetector #metamerism
