Does an additive number such as E 1520 describe the material in the drum?

No. An additive designation is an identifier used in food law for a permitted use of a substance, not a property that a container of raw material possesses. Whether a given use is permitted at all, in which food categories and under which conditions, is set by the rules in force in the market where the finished product is sold, and those rules differ between jurisdictions and change over time. The drum carries a specification and a set of documents; the permission belongs to the use, and verifying it is the food business operator's responsibility.

What actually differs between a technical and a food grade lot?

The molecule does not; the control regime does. A food grade lot is manufactured and tested against a published monograph rather than a house specification, which means a defined impurity panel with named analytical methods. Around that sit differences that are not chemistry at all: qualified production and packing lines, defined packaging and closures, a documented cleaning and changeover regime, traceability from raw material to delivery, retained samples, and a food safety management system with third-party certification. Assay alone does not distinguish the two.

Who is responsible for the compliance of the finished food?

The food business operator placing the finished product on the market. The raw material supplier is responsible for the lot conforming to the agreed specification and for the accuracy of the documents supplied with it. Those two responsibilities do not overlap: a conforming lot can still be used in a way, or at a level, or in a food category, that the destination market does not permit. No certificate from a supplier transfers the finished product obligation, and any supplier offering to carry it should be treated with caution.

Why does the tanker's previous load matter so much?

Because for a bulk liquid the vessel is part of the process. Residue from a previous cargo can carry into the next load, so food grade bulk transport is normally controlled by a combination of dedicated equipment, restricted prior load lists, documented cleaning to a defined procedure and a cleaning certificate travelling with the consignment. The control is documentary and preventive rather than analytical, since routine incoming testing will not reliably detect an unexpected residue whose identity nobody knows to look for.

Food grade propylene glycol: the raw material paperwork

Q: Which documents should a buyer expect with a food grade delivery?

A specification referencing the monograph applied, a lot certificate of analysis reporting against it with methods named, and a statement of conformity to the food grade standard claimed. Beyond that, buyers commonly require declarations on allergens, on genetically modified material, on animal origin, on nanomaterial content and on the materials of the packaging in contact with the product. For bulk deliveries a cleaning certificate and a prior load declaration for the tanker are normal. Agree the list before the first order; retrofitting declarations to a delivered lot is slow.

Technical article · Eapearl Chemical · 10 February 2026

For a purchaser, food grade is not a stronger version of a technical specification. It is a different control regime, most of which lives in documents, cleaning records and traceability rather than in the analysis of the molecule.

An additive designation describes a use, not a drum

Propylene glycol, CAS 57-55-6 and EC 200-338-0, is used industrially in a wide range of roles and appears in food legislation in several jurisdictions under an additive designation, commonly written as E 1520 where the European numbering is used. That number is not a property of the material. It is an identifier attached to a permitted use, and whether a particular use is permitted, in which food categories and subject to what conditions, is determined by the rules in force in the market where the finished product is sold.

The distinction matters commercially because it decides who has to check what. A supplier can state the standard a lot was made and tested against. Only the food business operator placing the finished product on the market can establish that the intended use is permitted where the product will be sold, at the level intended, in that category of food, and with the labelling the local rules require. This article deals only with the first of those questions: what a raw material lot has to be, and what has to travel with it.

What actually separates the grades

The molecule in a food grade drum is the same molecule as in a technical drum. What differs is the regime that produced and released it.

The reference document. A food grade lot is made and released against a published monograph rather than a producer’s house specification. The monograph fixes the identity tests, the impurity panel and the analytical methods, which is what makes two suppliers’ certificates comparable at all.
The impurity panel. A technical specification is usually written around assay, colour, water and acidity. A monograph adds named impurities and residues that are controlled because of the intended context of use, each with a stated method.
The production line. Qualified equipment, controlled changeovers, documented cleaning, and segregation from non-food production.
Packaging. Defined containers, liners and closures suitable for food contact, with documentation covering the contact materials themselves.
Traceability. Lot genealogy from raw material through to delivery, retained samples held for a defined period, and a recall procedure that has been tested rather than merely written.
The management system. A recognised food safety scheme, certified by a third party, with the certificate scope actually covering the site and the product in question.

That last point is worth reading twice. Certificates are frequently supplied whose scope covers a different site, a different product family or a lapsed period. Read the scope, not the logo.

The monograph is the reference; the certificate is the evidence

A specification that says only food grade says nothing testable. A usable specification names the monograph applied and the revision, lists the parameters with limits and methods, and states what is reported on each lot as opposed to what is verified periodically. A certificate of analysis should then report against that document, lot by lot, with methods named and the actual results given rather than a blanket conforms.

Two habits protect a buyer here. The first is to check that the parameters on the certificate are the parameters in the specification, since certificates are often generated from a template that has drifted from the agreed document. The second is to keep results as a trend across deliveries rather than reading each certificate in isolation. A value that stays inside the limit while moving steadily in one direction is information about the process, and it is the earliest warning available.

Statements that travel beside the specification

Much of what a food manufacturer needs is not an analytical result at all. Declarations on allergens, on genetically modified material, on animal origin, on nanomaterial content and on the packaging contact materials are routinely required, together with religious certifications such as kosher or halal where the customer’s market demands them. For bulk liquid deliveries, a cleaning certificate and a prior load declaration for the vehicle or tank are normal requirements rather than optional extras.

These documents are worth agreeing as a package before the first order. Each is straightforward to provide when the request is known in advance and awkward to retrofit to a lot that has already shipped. The same applies to the related polyols a food manufacturer may qualify alongside it, such as glycerol, triacetin or sorbitol; each has its own monograph and its own document set, and one supplier approval does not carry across to another material.

Segregation, prior load and the bulk question

For a bulk liquid the transport vessel is part of the process, and the main risk is carry-over from a previous cargo. Control is preventive and documentary: dedicated equipment where the volume justifies it, a restricted list of acceptable previous loads, cleaning to a defined and recorded procedure, and a cleaning certificate accompanying the consignment. Analytical testing on receipt is a poor substitute, because incoming testing looks for the parameters in the specification and an unexpected residue is by definition not among them.

The same logic extends into the receiving site. A food grade material stored in a shared tank farm, decanted with shared equipment or handled with hoses that also serve technical products has quietly lost the segregation the grade was bought for. If the internal handling does not preserve the control, the certificate at the gate has not achieved anything.

Traceability and being ready for the question

The purpose of lot traceability is to make one question answerable quickly: if a problem is found in a delivered lot, which finished batches contain it and where did they go. That requires the incoming lot number to be recorded against production batches at the point of use, retained samples to be kept and actually retrievable, and the supplier to be able to trace backwards from the lot to their own raw materials. Test the chain occasionally with a mock exercise rather than assuming it works. A traceability system that has never been exercised is a document, not a capability.

Where enquiries go wrong

Asking for food grade without naming the monograph, and receiving a house specification that happens to use the phrase.
Accepting a certification whose scope does not cover the manufacturing site or the product supplied.
Leaving allergen, origin and packaging declarations until after the first delivery.
Assuming that a technical grade lot with a good assay is equivalent because the analysis looks similar.
Preserving the grade to the gate and losing it inside the plant through shared transfer equipment.
Treating a supplier’s conformity statement as an answer to whether the intended use is permitted in the market of sale, which it is not and cannot be.

Specifications, monograph references, lot certificates and the associated declarations are supplied against a named application through our contact page; stating the intended use and the market of sale at enquiry stage is what allows the correct grade and document set to be quoted first time.