Gummy Jellies Sweat and Stick in Tropical Shipment
A confectioner produces gelatin gummies (water activity 0.62, pH 3.2, 8% gelatin, 45% glucose syrup, 30% sucrose) packed in 1 kg clear PET/PE pouches with a stated 12-month shelf life at 20°C/60% RH. A shipment to a distributor in a tropical region arrives after 6 weeks at 35°C/85% RH. The pouches are intact, but the gummies are stuck together in a block and have a sticky syrup film; some colours have faded. The plant’s retained samples stored at 20°C/60% RH are normal. The pouch film has a water vapour transmission rate of 8 g/m²/day at 38°C/90% RH. The distributor stores pallets near a loading dock. QA must advise the distributor and decide what to change for future shipments.
1. Explain the likely causes of the sticking and surface film, and why the retained samples did not show the defect.
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The retained samples were stored at 20°C/60% RH, so they did not experience the same driving force for moisture uptake. The pouch film’s water vapour transmission rate is high for a 12-month tropical shelf life: at 35°C/85% RH, moisture moves through the film into the low-aw gummy until the surface sugars hydrate. A sticky syrup film then forms, and adjacent gummies bond. Gelatin also softens as temperature rises; at 35°C the gel is close to its melting range, so the pieces deform and block together even before moisture uptake is extreme.
The loading-dock storage adds temperature cycling. Warm days and cooler nights can cause condensation inside the pouch or on the product, and repeated cycling drives sugars to the surface. Colour fading is consistent with heat and light exposure. The defect is therefore a distribution and packaging failure, not necessarily a production failure: the product met specification at the plant, but the pack did not protect it under the actual conditions.
2. What disposition would you recommend for the affected shipment, and what packaging and storage changes should be made?
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Recommend that the distributor hold the shipment and assess it before sale. Check for mould, off-odour, and whether the pieces are merely stuck or have slumped and lost shape. If there is no mould and the product is sound apart from sticking, it may be sold as a downgraded or repacked lot only with the customer’s agreement; if there is any mould or unacceptable texture, reject or destroy it. Do not simply relabel it with a shorter shelf life without evidence.
For future shipments, move to a high-barrier film with a much lower water vapour transmission rate, and specify the film by the actual shipping condition, not only 23°C/50% RH. Reduce the product’s tendency to pick up moisture by adjusting humectants and water activity within the recipe, and consider a surface finish such as a thin wax or starch coating if allowed. Specify cool, dry storage away from loading docks and direct sunlight; add a shipping trial at 35°C/85% RH for 6 weeks with periodic inspection. Update the shelf-life claim to state the storage conditions it depends on.
3. How would you design a verification trial to prove the new pack works before committing to a full production run?
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Run a side-by-side challenge with the current film and the proposed high-barrier film, using product from the same batch. Store pouches at 35°C/85% RH for at least 6 weeks, with a second condition at 30°C/75% RH and a control at 20°C/60% RH. Include temperature cycling to simulate the dock: for example, 35°C for 12 hours and 25°C for 12 hours. At weekly intervals, measure weight gain, water activity, and firmness, and assess sticking, surface film, colour, and mould. Photograph the product under standard lighting.
Set acceptance criteria before the trial: no mould, no unacceptable sticking, water activity within a defined range, and colour within an agreed tolerance. Compare the film’s measured water vapour transmission rate with its specification and with the trial results. If the new film passes, run a plant trial with the actual packing line to check seal integrity and headspace, then a monitored shipment. Document the trial in the shelf-life file and use it to justify the label storage conditions.