Yamanaka 2025 - Tin migration from unlacquered tinplate pineapple cans

Yamanaka studied corrosion of unlacquered tinplate cans used for fruit by storing commercially available pineapple cans at 43 C and measuring tin and iron in the combined pineapple solid-plus-syrup fraction. The paper is not a general pineapple field-contamination study; it is migration evidence for tinplate food-contact packaging under accelerated storage. Tin in pineapple syrup rose from about 30 ppm at the beginning of the pack test to 310 ppm by 6 months, while uncanned pineapple was below 0.1 ppm Sn.

Key numbers

The accelerated pack test used commercially available pineapple cans with an unlacquered tinplate inner surface. Three cans were mixed to form one analytical sample at each pull.

The authors report that the tin dissolution rate was 23-33 ppm/month from the initial stage to month 3, then 58-70 ppm/month from month 3 to month 6. The can inner surface was visibly gray near the waterline by month 4 and gray across the immersed inner surface by month 6. Pineapple syrup pH remained around 3 at month 6.

Table 4 reports the uncanned pineapple syrup composition used for electrochemical context: citric acid 0.64 g/100 g, malic acid 0.18 g/100 g, nitrate 0.0032 g/kg, and oxalic, tartaric, succinic, fumaric, acetic acid, lactose, and nitrite below their listed detection limits.

Methods (brief)

Cans were stored in a thermohygrostat at 43 C and removed after 1, 2, 3, 4, and 6 months. The pineapple solid fraction was squeezed and recombined with syrup to form “pineapple syrup” for pH and metal analysis. Tin and iron in pineapple syrup were measured by ICP-MS using an Agilent 7900ce. Can interiors were examined visually, by scanning electron microscopy, and by EPMA for Sn and Fe X-ray intensity. Electrochemical measurements used tin, tin-iron alloy, and steel plates immersed in pineapple syrup with an Ametek SI VersaSTAT4 potentiostat-galvanostat.

Implications

• Product and packaging routing: Adds direct tinplate-migration evidence for acidic canned fruit, specifically pineapple packed in unlacquered tinplate.
• Basis handling: The measured food-side matrix is combined pineapple solids plus syrup after accelerated storage, reported as ppm in pineapple syrup. These values should not be treated as ambient retail occurrence without the accelerated-storage condition.
• Speciation: The paper measures total tin by ICP-MS. It does not measure organotin compounds and does not separate Sn(II) from Sn(IV).
• Courses: Useful mechanism source for why acidic canned fruit has higher inorganic-tin migration risk than neutral-pH products and why headspace oxygen and exposed tin-iron alloy accelerate corrosion.

Wiki pages this source may touch

• pineapple
• canned-fruit
• food-packaging-cans-lids
• tin
• tin-inorganic
• iron

Verification notes

• The paper is packaging-migration evidence, not agricultural heavy-metal uptake in pineapple.
• Values are accelerated-storage values at 43 C; route them with the storage-condition caveat.
• metals: [Sn, Fe] reflects total tin and iron measured in the pineapple syrup by ICP-MS. The toxicologically relevant food-packaging metal for this ingest is Sn; Fe is captured because the source uses Fe dissolution to identify late-stage base-steel corrosion.
• The PDF is an advance-view manuscript from Materials Transactions, published July 4, 2025. No open license statement was visible in the PDF text.

Page history

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