Innova-Nation · Colegio Agustiniano
The color tells you when it's no longer.
FreshTag is a smart label that uses a natural anthocyanin indicator to show, with a simple color change, how fresh a food item is — no sensors, no battery.
Fresh
pink · pH ≈ 5.5
The anthocyanin indicator is at its original shade. The food is in optimal condition.
The problem
The expiration date is a generic estimate, not a real data point
Two packages with the same printed date can be in completely different states of freshness, and there's no way for the consumer to know just by looking at the label. The result is two opposite problems happening at once: good food gets thrown away, and food that's no longer safe gets eaten.
0
metric tons
of food wasted in households in 2022 — 60% of all food wasted across the entire supply chain
Food Waste Index Report 2024, UNEP
0
cases / year
of foodborne illness, with 420,000 associated deaths
WHO, 2015 reference report
0
of the burden
of that disease burden falls on children under 5, who make up just 9% of the world's population
WHO
0
of the population
— 2.4 billion people — faced moderate or severe food insecurity in 2022
SOFI 2023 Report, FAO/IFAD/UNICEF/WFP/WHO
The science
Anthocyanins: the same pigment in purple cabbage
Anthocyanins are natural pH-sensitive pigments. In an acidic environment they're pink or purple; in a basic one they shift toward blue or green. As food spoils, it releases volatile amines and ammonia that make the environment more basic — and that's exactly what FreshTag's indicator translates into a visible color change.
Cyanidin — the anthocyanidin in purple cabbage · flavylium cation + 5 hydroxyls · drag to rotate
Detects gas, never touches the food
As meat spoils, it releases volatile biogenic amines — alkaline substances that spread through the sealed air inside the package without any liquid contact. The indicator lives inside a small breathable sachet, the same principle as a tea bag: it lets gas through and blocks liquid. That way the food's condition can be sensed without ever touching it.
Gases detected (biogenic amines)
- Ammonia
- Trimethylamine
- Putrescine
- Cadaverine
Sandwich structure, 3 layers
So meat juices don't wash out the sensor, the indicator is never directly exposed — it's protected between a visible face and a filter that only lets gas through.
01
Front layer — consumer-facing
Conventional clear plastic (PET/PP) with the QR code and reference color scale printed on it.
02
Middle layer — sensor
A porous matrix impregnated with the anthocyanin indicator. This is the part that reacts.
03
Back layer — gas filter
A hydrophobic microporous membrane (Tyvek-type or waxed paper): repels meat juices but lets gas through to reach the sensor.
The app handles the last step: you scan the color or the QR code on the label and see the status — pink, violet, or blue — instantly, without relying on the eye to tell the difference precisely.
Accessible by design, not as an afterthought
The color scale wasn't chosen for the chemistry alone — it also had to work for people who can't rely on color at all.
01
Outside the red-green axis
Pink, violet, and blue don't collapse into each other under red-green color blindness — the most common type, affecting close to 8% of men — unlike a traditional green/yellow/orange/red traffic-light scale.
02
Never color alone
The status always appears as a word too — “Fresh,” “Starting to spoil,” “Do not eat” — never just a colored circle.
03
The app already reads it out loud
An optional feature, turned on with a speaker icon under “Read color aloud”: it announces the status the moment it changes, for people with low vision or blindness who can't rely on color at all.
Thinking about the planet
Future vision — not yet implementedHonesty first: today's prototype isn't compostable. The indicator is — the rest of the label isn't yet.
01
The indicator is already 100% natural
Purple cabbage (anthocyanins): an edible pigment, not a synthetic dye. It's food-safe by nature, not because of some added certification.
02
The rest of the layers, today, aren't
The front layer (PET/PP) and the back membrane (Tyvek or conventional waxed paper) are ordinary plastic — they work well, but they aren't compostable.
03
On the road to a compostable version
Clear bioplastic (PLA or cellulose acetate) for the front layer, and plant-wax paper or a cellulose membrane for the back — same principle, smaller footprint. The same ambition Oscillum already shows with its biodegradable label.
Technical specs
The essentials, at a glance
Indicator
Purple cabbage anthocyanins on filter paper or agar-agar gel
Traceability
QR code linked to a digital data sheet (batch, process, estimated expiration)
Prototype cost
US$15–30 (30–40 test labels), cents per additional label
Production at scale
Continuous roll-to-roll line: flexographic QR printing, reagent injection, and membrane lamination — US$0.015–0.03 per label
Strengths
- +The chemical principle is backed by peer-reviewed research — it's not an idea without support.
- +A double signal — color plus QR — that doesn't rely on blindly trusting a generic printed date.
- +It integrates with infrastructure that already exists (scale and thermal label), rather than replacing it.
Honest limitations
- –There's no in-house experimental data yet — calibration is a defined procedure, not measured results.
- –The 3-color scale is a coarse approximation compared to a continuous pH scale.
- –It has no validation from any health authority: it is not presented as a guarantee of food safety.
Evidence
Not an isolated idea
The same principle — detecting food spoilage through the gases or color it produces — already has real-world cases, some of which started as student projects.
Oscillum
Elche, SpainA biodegradable label that shifts from yellow to blue depending on the freshness of meat and fish. Named among the world's 10 most promising young innovations at the European Patent Office's Young Inventors Awards 2025.
Mimica Touch
United KingdomIt started as an industrial design thesis ('Bump Mark') that won the UK national round of the James Dyson Award 2014. Today it's funded by the Seafood Innovation Fund and Innovate UK — the student-to-product path this project treats as a reference.
Purple cabbage research
Foods journal, Oct. 2024Peer-reviewed studies confirm that purple-cabbage-anthocyanin indicator films detect spoilage in meat, fish, and shrimp with good sensitivity — the same principle FreshTag uses.
PEGS
Imperial College LondonA paper sensor with printed electrodes and an NFC chip that detects ammonia and trimethylamine. It doesn't use color, but it confirms that sensing spoilage gases inside packaging is a real research priority today.
The project
An Innova-Nation pilot
FreshTag was born through Innova-Nation, the school entrepreneurship and innovation program at Colegio Agustiniano Nuestra Señora del Buen Consejo. Today the physical label is a chemical prototype being calibrated; the app is being built in parallel so the demo works start to finish.
What the app looks like today
Real, not a mockup01
Read Color
The camera turns on by itself when you open it — no home screen, no capture button.
- •Compares the live sample, several times a second, against the freshness traffic-light reference states.
- •Detects the QR code with the same camera, at the same time — no mode switch.
- •Before saving anything it asks "Are you taking this product?" — nothing gets added without confirming, and an ignored tap counts as "no."
- •If the product is already in the log, it says so instead of duplicating it.
- •Every state can be read aloud (optional speaker icon) and always carries a glyph, not just a color.
- •Honestly: it still uses the previous 4-color scale (green/yellow/orange/red) — moving it to pink/violet/blue, matching the physical label, is the next pending step.
02
My Log
The list of scanned products, sorted by how close they are to expiring.
- •Total, "expiring soon," and "expired" counts at a glance.
- •Real expiration reminders, with a clear notice when they're unavailable (Expo Go, the web version).
- •Add a product by hand, with a built-in QR generator for printing onto the label.
- •Each product opens a detail sheet with all its data and a recipe idea.
- •Light, dark, or system appearance — independent of the phone's own setting.
Coming soon, on your phone
The Android APK and the installable web version (PWA) will be available here as soon as the first phases of the app ship.
Download APK — coming soon