THE TECHNOLOGY
Modified Atmosphere + Modified Humidity
THREE TRANSMISSION RATES — OTR · CO₂TR · WVTR
A Biopac MAP bag is a precision-engineered film liner that does two things at once — and both matter for shelf life:
Efficient Humidity Control
Modified Atmosphere · MA
Produce keeps respiring after harvest, consuming O₂ and releasing CO₂ inside the sealed bag. As O₂ falls and CO₂ rises, a concentration gradient builds across the film. The film’s polymer structure lets gas diffuse through it at an engineered rate — the OTR and CO₂TR — letting O₂ back in and CO₂ back out fast enough to avoid fermentation, but slow enough to hold the atmosphere in the low-O₂, high-CO₂ band that suppresses respiration and ripening. Equilibrium is reached only when gas diffusing through the film matches the rate the fruit is consuming and producing it.
Modified Humidity · MH
Vents excess moisture while holding the optimal relative humidity — no condensation, no dehydration.
The film delivers both — precisely, and tuned to each crop — through three transmission rates:
OTR · Oxygen
Oxygen Transmission Rate — how fast O₂ enters. Sets the low-O₂ level the produce respires down to: the primary respiration brake.
CO₂TR · Carbon dioxide
CO₂ Transmission Rate — how fast CO₂ escapes. Sets the elevated CO₂ that further slows respiration and suppresses decay.
WVTR · Water vapour
Water-Vapour Transmission Rate — how fast moisture leaves. Expels condensation while holding the correct humidity (90–95% RH).
— GAS EQUILIBRIUM
OTR + CO₂TR settle O₂ and CO₂ into the optimal band for that crop; WVTR holds the humidity. Result: slower ripening, retained firmness & colour, less moisture loss and decay.
Once equilibrium is reached, the bag holds that low-O₂, high-CO₂ atmosphere as a steady state for the rest of storage — not a one-time effect. At that suppressed respiration rate, the produce uses less energy, produces less ethylene, and releases less heat and moisture, which is where the downstream benefits actually come from: slower ripening, less decay, less moisture loss. This equilibrium is temperature-dependent, though — respiration rate rises faster with temperature than film permeability does, so a warm break in the cold chain shifts the balance. That’s why the temperature swings a shipment goes through, covered further down this page, matter as much as the bag’s specification itself.
— ONE BAG CANNOT FIT ALL
Each variety has different post-harvest biology — so each needs its own OTR / CO₂TR / WVTR. Example: optimal MAP conditions across a range of produce.
| VARIETY | TEMP | O₂ | CO₂ |
|---|---|---|---|
| Nectarine | 0–2 °C | 3–5% | 5–10% |
| Lychee | 1–5 °C | 3–5% | 3–5% |
| Passion Fruit | 7–10 °C | 3–5% | 5–10% |
| Broccoli | 0–1 °C | 1–2% | 5–10% |
| Melon | 3–7 °C | 3–5% | 10–15% |
Each variety gets a bag matched to its exact OTR, CO₂TR and WVTR — engineered, never generic. Works with all fruit, vegetables and flowers; supplied as box / crate liners, retail packs and pallet covers.
ORGANIC
Compatible with organic produce
The MAP bag is inert packaging film that adds nothing to the fruit — so it suits certified organic export and domestic supply programmes, where treatments like 1-MCP or SO₂ are not permitted.
— THE BENEFITS
What Modified Atmosphere Packaging Does for Shelf Life
Modified Atmosphere Packaging extends the shelf life of fruits, vegetables and flowers:
Slows the ripening process, maintaining firmness.
Reduces moisture loss and dehydration.
Blocks the mode of action and biosynthesis of ethylene, the plant hormone which promotes senescence.
Reduces rots by directly inhibiting the growth of pathogens.
Slows yellowing of green tissues by preventing chlorophyll degradation.
WVTR IN ACTION
Two Sources of Moisture — WVTR Removes Both
THE REAL DIFFERENCE ON A 10–14 DAY EXPORT VOYAGE
— WHERE THE MOISTURE COMES FROM — TWO SOURCES THAT ADD UP
1 · Produce respiration
Even sealed and chilled, produce keeps living — respiring O₂ into CO₂ and releasing heat and water vapour. Inside the sealed bag the humidity climbs continuously toward saturation.
2 · Temperature variation
No voyage holds a constant temperature: packhouse 28–35°C → pre-cool 0–2°C → sea fluctuations → 20–30°C at arrival. Every drop makes the warm, moisture-laden air shed water as condensation.
The two add up: respiration steadily loads the sealed bag with moisture, and each temperature drop condenses that moisture onto the fruit skin and film. In a low-WVTR bag the water has nowhere to go — it pools at the base and creates ideal conditions for Botrytis, Monilinia and fungal decay.
Too much moisture inside a sealed bag is not a cosmetic problem — it is one of the fastest routes to a rejected shipment. Free water on the fruit surface breaks down the skin’s natural defences, gives fungal spores like Botrytis and Monilinia a wet surface to germinate on, and accelerates softening. Once condensation starts, it compounds: wetter fruit respires faster, faster respiration produces more moisture, and the cycle feeds itself for the rest of the voyage. This is why relative humidity control is not a secondary feature of a MAP bag — it is as critical to shelf life as the O₂ and CO₂ balance itself.
— REAL EVIDENCE — GENERIC VS BIOPAC (APRICOTS)
WHY ONE BAG CANNOT SERVE EVERY CROP
Every produce variety has its own respiration rate — the speed at which it consumes O₂ and releases CO₂ and moisture. A generic bag has a single fixed OTR, CO₂TR and WVTR, so the atmosphere it creates inside the package is determined by the film, not by the crop. For one variety that atmosphere may be close enough; for another it will be too high in O₂, too low in CO₂, or too humid — accelerating ripening, condensation and decay. Biopac calibrates each bag to the exact respiration rate of the crop, so the atmosphere that develops inside is precisely the one that crop needs.
Generic MAP bag — condensation pooling on apricot skin. A fixed film not calibrated to this crop’s respiration rate.
Biopac MAP bag — OTR · CO₂TR · WVTR calibrated for apricots. Dry surface, correct RH, full shelf life.
Biopac’s high WVTR expels excess moisture within 24 hours — from both respiration and condensation — while holding 90–95% RH. Paired with crop-matched OTR and CO₂TR, the result is slower ripening, retained firmness and zero condensation damage. One bag, calibrated for one crop. Never generic.
ETHYLENE CONTROL
Works Alongside Fresh Up® Ethylene Sachets
For ethylene-sensitive climacteric produce — plum, passion fruit and melon are good examples — a Lifepack® MAP bag can be combined with a Fresh Up® ethylene absorber sachet or filter. The bag manages O₂, CO₂ and humidity; Fresh Up® removes the ethylene that accumulates inside the sealed environment, which is what these crops are most sensitive to as they ripen.
Fresh Up® sachets use potassium permanganate (KMnO₄) to absorb and chemically convert ethylene inside the bag, rather than simply trapping it:
GRAPE STORAGE
Grape Storage with Modified Atmosphere + Modified Humidity
Biopac is a grape packaging supplier for conventional and organic table grapes to Australia and the USA. Biopac has recently developed a modified atmosphere bag for table grapes, engineered specifically to solve the problems common in grape storage.
The Biopac Modified Atmosphere bag used in fresh fruit packaging extends the shelf life of table grapes by:
Result of application Lifepack Plus (3 weeks at 1 C)
Keeping O₂ and CO₂ at optimum levels to inhibit senescence of the fruit.
Holding relative humidity inside the bag at the optimum level.
Inhibiting desiccation and browning of pedicels, rachis and berries.
Inhibiting decay-causing microorganisms with antimicrobial properties.
Combined with an SO₂ pad, storage of up to 12–14 weeks is achievable, depending on the table grape cultivar.
HOW IT’S SUPPLIED
Packaging Types
Box / Crate Liners
Fitted inside individual boxes or crates, sealing each unit in its own calibrated atmosphere.
Retail Packs
Consumer-facing packs that carry the same MA/MH protection through to the shelf.
Pallet Covers
Full-pallet coverage for bulk shipments, maintaining atmosphere control at scale.
Biopac Clips
Clips provide an effective seal. Clip closure and release is fast, simple, requires little training, and is reliable — with excellent seal consistency.
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