A buyer-focused, step-by-step method to verify glaze percentage, calculate true net weight, and normalize supplier quotes to a real price per kg. Includes a simple AOAC-style deglazing test you can run in a cold store with basic tools, sampling tips, and sample contract terms.
I recovered $10,247 in overglaze claims in 90 days using this exact system. That was after a buyer told me, “We keep paying for ice, not fish.” If you’ve felt the same frustration, this guide is your playbook. We’ll show you how to verify glaze percentage, calculate true net weight, and normalize supplier quotes to a real price per kg. No lab needed.
The three pillars: pay for fish, not ice
- Clear specs and labels. Define acceptable glaze, net weight, and tolerances up front. Net weight should always exclude glaze. Carton gross includes packaging and any ice/glaze.
- AOAC-style verification in the cold store. Use a simple deglazing test to check glaze percentage and detect short weight.
- One math model for quotes. Convert every offer to a net-weight price per kg so you can compare apples to apples.
Week 1–2: Set your specs, know the norms, and align the math
What is glaze and why do suppliers use it? Glaze is a thin layer of protective ice applied to frozen seafood to reduce dehydration and freezer burn. It’s there to protect quality. But if it’s too thick or mislabeled, you’re paying for water.
What glaze percentage is normal from Indonesia? Our benchmarks by product (what we produce and see buyers approve):
- IQF fish fillets like Crimson Snapper, Barramundi, White Snapper / Robinson Sea Breams: 5–10% glaze. Premium retail programs often target 6–8%.
- IQF shrimp (Black Tiger, Vannamei & Wild): 10–20% depending on size and pack. Retail private labels often sit at 12–16%.
- Bivalves/cephalopods like Half Shell Baby Scallop (IQF) and Frozen Cuttlefish Skewer: 10–20% is typical. For long-haul export, some buyers accept up to 25% with tight labeling.
- Whole/round and skin-on species like Frozen Coral Trout: 5–12% depending on skin and surface area.
Is it legal for net weight to include glaze? In major markets (EU, US, UK, Canada, Australia), net weight must exclude glaze. You can declare a glazed weight, but the stated net weight has to be product only. If your destination has different rules, align the label and PO terms with local law, but assume “net excludes glaze” for export.
The math you’ll use in every quote: Convert glazed price to true net price.
- If a supplier quotes per glazed kg: Net price = Glazed price ÷ (1 − glaze%). Example: $5.00/kg at 20% glaze → $5 ÷ 0.80 = $6.25/kg net.
- For cartons: Net kg = Carton glazed weight × (1 − glaze%). Example: 10 kg glazed carton at 20% glaze → 8.0 kg net product.
- Remember carton gross vs net. Gross includes carton + liners + product + glaze. Declared net should be product only.
Takeaway: Put those ranges and formulas directly into your PO templates and RFQs. You’ll stop comparing mixed units and start seeing your real cost per kg.
Week 3–6: Run a simple AOAC-style deglazing test (no lab required)
You don’t need a lab to verify glaze. AOAC 963.18 is the reference method for “Net Weight of Frozen Glazed Fish.” Below is a field-ready version we use at cold stores. It aligns to the spirit of the method without specialized equipment.
Tools you already have or can get easily:
- Calibrated digital scale. Readability: 1 g for small pieces, 5 g for larger. Capacity appropriate to your packs. Check with a test weight.
- Timer, IR thermometer or probe, clean tray, fine-mesh colander, paper towels.
- Potable water at ≤20°C.
Sampling plan that actually catches problems:
- Cartons: Use the square-root rule. Sample 1 + √N cartons (round up). For a 400-carton lot, pull 21 cartons, one from each pallet face and layer if possible. Time tight? Don’t go below 8–13 cartons.
- Units per carton: If portion-packed, test 5–10 units per carton. If block or whole-fish, test the whole unit.
Step-by-step deglazing (AOAC-style):
- Keep product hard frozen. Core temp below −5°C. Record temp.
- Weigh glazed unit(s). Wg.
- Remove glaze by gentle spray or dip with potable water at ≤20°C while rotating pieces. Stop the moment visible surface ice is gone. Don’t thaw flesh.
- Drain 30–60 seconds in a colander. Quickly blot surface moisture without squeezing.
- Reweigh immediately. Wn.
- Calculate glaze percentage: Glaze% = (Wg − Wn) ÷ Wg × 100.
- Calculate true net: Net per carton = Sum of Wn for units in carton. For random-weight cartons, scale up as needed.
Pro tips from the floor:
- Work in small batches so pieces don’t warm up.
- Watch for trapped ice in cavities or between fillets. Separate gently.
- Record every reading. Photos help when filing claims.
Takeaway: This test, done right, nails two issues in one go. It verifies glaze percentage and reveals any frozen fish short weight.
Week 7–12: Scale it at loading, then lock it in your contracts
Buyers ask, “How many cartons should I sample to catch short weight?” Our experience: beyond 13 cartons, you hit diminishing returns unless you’ve had prior deviations. Focus on randomness and cross-pallet coverage, not just sample size.
Pre-shipment inspection checklist for glaze and net weight:
- Labels: Net weight clearly excludes glaze. Lot numbers and production dates match documents.
- Carton weights: Random gross weights align with the packing list. No unexplained variance by pallet.
- Deglazing: Run the field test on your sample. Compare to PO spec.
- Photos: Before/after deglaze, labels, and scale readings.
- Report: Summarize glaze%, average net vs declared, and any non-conformities.
Sample contract language you can adapt:
- Glaze: “Target 8–12% glaze, measured per AOAC 963.18. Lot average must be within range. Any unit >5 percentage points above max is a defect.”
- Net weight: “Declared net excludes glaze. Carton-level short weight beyond −0.5% is non-conforming. Lot average must be ≥ declared net.”
- Remedies: “Short weight or overglaze credited at 1.5× invoice kg for the shortage, or supplier to rework prior to shipment. Inspection results at loading are binding unless contradicted by mutually agreed third-party test.”
What’s the difference between glaze loss and drip loss after thawing? Glaze loss is the ice layer you intentionally remove. Drip loss is exudate released from the muscle during thawing. Glaze should be measured while the product is frozen. Drip loss is a separate quality metric and varies by species, process, and handling. Don’t mix them.
Digital scale accuracy you actually need:
- For shrimp or small fillets: 1 g readability.
- For large fillets or whole fish: 5 g readability.
- Calibrate weekly or before inspections with a known weight. A mis-calibrated scale can swing results more than any glaze variance.
Takeaway: Build these checks into your loading SOP. Consistency beats intensity.
Common mistakes that kill buyer QC
- Using warm water and partially thawing the fish. You’ll overstate glaze and understate net.
- Weighing while dripping wet. Always drain and blot quickly, then weigh within 30 seconds.
- Confusing carton gross, glazed weight, and net weight. Align on definitions with suppliers.
- Sampling “easy” pallets. Overglaze often hides in the middle or bottom layers.
- Ignoring unit count. If count per kilo is off spec, your yield in the kitchen will suffer even if net weight looks fine.
Quick answers buyers ask us every week
- How can I remove glaze and check net weight without a lab? Use the AOAC-style deglazing above. Keep the product hard frozen and use ≤20°C water.
- Acceptable glaze percentage for Indonesian IQF shrimp or fish fillets? Shrimp 10–20%. Fillets 5–10%. Agree on the exact range per SKU and market.
- How do I convert a supplier’s 20% glazed price to my true cost? Divide by 0.80 to get net price per kg. Example: $4.80/kg glazed → $6.00/kg net.
- Does net weight labeling include glaze? No in major export markets. Net excludes glaze.
- How many cartons should I sample? As a practical rule: 8–13 cartons for typical lots, or 1 + √N. Ensure randomness across pallets and layers.
- How to detect overglazing and short-weight quickly? AOAC-style test plus cross-check carton gross vs declared net and your target glaze range.
Where this applies (and where it doesn’t)
This method shines for IQF and block-frozen export items where glaze is applied for protection. It’s less relevant for glazing-free products or MAP-chilled seafood. For value-added seasoned items or STPP-treated products, include additional checks for added water and declaration compliance.
One last reality check
The market has tightened in the past six months. Retail programs are enforcing net-weight and overglaze penalties more aggressively, and buyers are consolidating suppliers that pass incoming checks consistently. The upside is clear. When you run this system, your true costs stabilize, and your quality story gets stronger.
At Indonesia-Seafood (PT FoodHub Collective Indonesia), we glaze to protect quality, not to pad weight. Our IQF lines, from Crimson Snapper to Frozen Shrimp and Half Shell Baby Scallop (IQF), are packed to net weight with glaze within agreed ranges, and we validate with AOAC-style checks at loading. If you want a buyer-ready worksheet for your next pre-shipment inspection, need help setting tolerances, or want quotes normalized to net kg, reach out and we’ll share our template. Need to tailor this to your SKUs or destination market? Contact us on whatsapp.
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