1. BY2 is a system risk, not only an end-point test
Thailand's Department of Agriculture applies surveillance and testing measures for Basic Yellow 2, or BY2, in export durian alongside other contaminants. Risk is not limited to direct application on fruit: cross-contamination may arise from crates, work areas, tools, clothing or gloves that contact a new lot.
Effective control starts with prohibition, verifiable cleaning, separation of clean and risk-zone tools, chemical approval and supplier or contractor controls. If the system relies only on final testing, the cost of holding and investigation arrives after fruit has already been consolidated or prepared for export.
2. Separate three evidence layers: prevention, screening and confirmation
Prevention evidence includes prohibited-substance lists, Big Cleaning records, surface checks, chemical approval and training. Screening evidence supports early warning and internal decisions. Confirmation evidence comes from a laboratory accepted under current requirements and supports the applicable export documentation.
Each layer answers a different question. Prevention asks whether causes are controlled. Screening asks whether a signal warrants a hold or investigation. Confirmation records the result produced through the required formal process. Any use of the word ‘pass’ should identify the layer, method and lot to which it refers.
3. Read screening-device numbers within their stated scope
NSTDA's 17 July 2025 publication reports that N-sense can complete a test within 20 minutes, detect as low as 0.56 ppb and achieve accuracy above 85%. The same source expressly says the device is for preliminary screening and cannot replace an accredited laboratory test used for export documents.
On 6 March 2026, NSTDA again presented portable BY2 analysis technology at an Eastern Region Field Day and described its role as preliminary screening. Inclusion in that event must not be expanded into a regulatory approval claim or a claim that any user may issue certificates.
4. Build an auditable BY2 evidence chain
Every sample should carry an identifier linked to orchard, supplier, intake point, lot, sampling date and time, sampler, peel location, preparation method, device model or identifier, calibration status, result and resulting decision. A photograph alone is weak evidence when it cannot be traced back to the lot and accountable owner.
- Hold Gate: stop lot movement when a signal is abnormal or records are incomplete.
- Investigation Gate: review areas, equipment, people, suppliers and potentially connected lots.
- Confirmation Gate: submit samples under the required method to a laboratory with current accepted status.
- Release Gate: an authorized person checks confirmation, supporting documents and chain-of-custody completeness.
- Claim Gate: communication uses only evidence-supported wording and never converts screening into ‘certified’.
5. Turn operational QC into buyer confidence
A good system need not expose all confidential data to a buyer, but it must be able to show who checked what, when, by which method, how the result informed a decision and where confirmation is held. A permission-controlled Lot Evidence Pack shortens response time, reduces wrong-lot documentation and gives investigations a reliable starting point.
Siam Diamond does not claim that the illustrated device is N-sense, that it operates a laboratory or may issue certificates, or that any product or lot has passed BY2 testing. This article explains an evidence architecture from official sources. Operators must verify current requirements and laboratory listings before acting.
