Potato starch vs potato flour vs potato flakes vs granules

Potato starch is the refined starch of raw potatoes. It is starch only, with the protein and fibre washed out. It is a thickener: it will not rehydrate to mash and it carries no potato flavour (what potato flakes are not).

It is made by separating the potato into its parts. A review of potato starch technology describes plants that separate the cell juice, which the industry calls fruit water, early in the process, take out the fibre, and refine the starch with nozzle separators that remove about 98% of the fine fibre; modern plants extract about 95% of the starch in the potato (Bergthaller, Witt and Goldau, Starch/Stärke, 1999).

What sets it apart from other starches is phosphorus. Potato starch has a high concentration of phosphorus, which gives it high viscosity, and starch from late-harvested potatoes shows higher peak viscosity (Noda, Japan Agricultural Research Quarterly).

For customs, native potato starch is 1108.13 (USITC). Modified starch made from potato is classified elsewhere, under 3505.10, dextrins and other modified starches (USITC).

Two different products share the name, so ask which one you are being offered. Raw potato flour is milled from uncooked potato and still needs cooking. Cooked potato flour is cooked, mashed and drum-dried potato, milled finer than flakes.

They behave differently in a dough (what potato flakes are not). Poorti's potato flour is the cooked kind: the finest mill of the flake range, made on the same line as the flakes. It is a binder and coating carrier. It takes up water, holds a patty together and crisps under fry, and it is milled to the mesh you order (potato flour).

Both kinds of potato flour fall under 1105.10, flour, meal and powder of potatoes (USITC).

Potato flakes are cooked mashed potato dried in a thin sheet and broken into flakes. Hot water or milk returns them to mashed potato, which is why they are sold as instant mash.

The customs definition says the same. Japan Customs, classifying potato flakes under 1105.20, quotes the HS Explanatory Note: these products may be obtained by steam-cooking and mashing fresh potatoes, then drying the mash to a flour, powder or granules, or to thin sheets cut into small flakes (Japan Customs classification ruling). The same note allows very small amounts of antioxidants, emulsifiers or vitamins.

Poorti's line runs in seven steps: intake, wash, peel, steam-cook, mash, drum-dry and pack (how the potato line runs). Only potatoes above 20% solid content enter the line. The cook is on high-pressure steam with no water entering it, the shelf-life additives are dosed at the mash, and the drum dryer forms a thin sheet that is milled to the particle size ordered.

The full specification, with microbiological limits, nutrition, packing and container loading, is published with the specification.

Granules are the same cooked potato base as flakes, dried in a different dryer. They are denser, free-flowing and slower to hydrate (what potato flakes are not).

Flakes, granules and pellets share subheading 1105.20 (USITC). Specify granules only if your line runs on them today. A line set up for granules will need its water and mixing time checked before it takes flakes.

Starch is a fraction of the potato. The other four are the whole potato, dried. That one difference decides what each can do.

A short test: buy flakes when you want potato you can taste and see, and cooked flour when you want potato that holds the product together (flakes and flour compared).

Potatoes contain no gluten, so potato flour, flakes and starch start gluten free. The risk is cross-contact with wheat, rye or barley in the fields, mills and packing lines the potato passes through.

NHS dietetic guidance lists potatoes among the foods that are naturally gluten free, and warns that cross contamination can occur during storage, processing and manufacturing (Kent Community Health NHS Foundation Trust).

The label is a legal claim with a number behind it. In the United States, gluten-free means the food contains no ingredient from wheat, rye, barley or their crossbreeds that has not been processed to remove gluten, and any unavoidable gluten is below 20 ppm (FDA final rule, Federal Register, 5 August 2013). In the UK the gluten-free label can only be used on foods at 20 ppm or less (Cambridge University Hospitals NHS).

Cross-contact is not a theory. A US study tested 22 naturally gluten-free grains, seeds and flours that were not labelled gluten-free; 7 of them carried gluten at 20 ppm or more, and the highest mean was 2,925 ppm (Thompson, Lee and Grace, Journal of the American Dietetic Association, 2010).

If your pack will say gluten free, ask for the allergen statement for the lot you are buying, and test the lot yourself. The general rule about potatoes is not a statement about any one mill or shipment.

Rarely one for one. Starch and flour are different materials, and the cooked products differ from each other in particle size and hydration.

• Potato flour for potato starch: no. Flour is the whole potato and carries its body and flavour; starch is a neutral thickener. A formula built on one will not behave the same with the other.
• Potato starch substitute: another starch, not potato flour or flakes. Potato starch gets its high viscosity from its phosphorus (Noda, JARQ), so test any other starch at your own dose before you change a formula.
• Raw potato flour for cooked potato flour: not directly. The raw flour still needs cooking and behaves differently in dough.
• Potato flakes for cooked potato flour: sometimes. They are the same cooked base, but flour is milled finer and is the one bought to bind and coat.
• Potato granules for flakes, or flakes for granules: only after a trial. Granules are denser and hydrate more slowly.

Do not substitute without a trial where the product depends on texture: instant mash, sheeted or extruded snack dough, or a batter that has to crisp in the fryer. Re-run your allergen and labelling checks whenever the material or the maker changes.

Flakes are the mash and the snack dough. Cooked flour is the binder, the coating and the bakery flour (what potato replaces).

• Snacks and pellets (flakes): the dough base for extruded and sheeted snacks, half-product pellets and fabricated crisps.
• Mash and ready meals (flakes): instant mashed potato for retail and catering, croquettes, dumplings, stuffed pasta, and shepherd's pie and frozen meal toppings.
• Frying and coating (flour): fish and meat coating systems and batter systems. The flour carries the coating and crisps under fry.
• Binding (flour): patties, vada, cutlets and koftas, where the flour takes up water and holds the product together.
• Bakery (flour): bread softness and moisture retention.
• Thickening (flour or starch): cooked potato flour thickens soups, sauces and gravies and brings potato body with it; potato starch thickens without flavour.

For snack makers, the Indian snack ideas guide lists the dry farsan that travel in a sealed pack. Several are potato-based.

The material and the cut, what you make with it, and the limits you must not break. The application matters most, because it decides which maker in the circle runs your order.

• Material and cut: flakes or flour, and the particle size or mesh you buy to today. If you buy flour, say whether it is cooked or raw.
• What you make with it: one line is enough.
• Volume and frequency: tonnes per shipment and shipments per year.
• Destination port and Incoterm: FOB Mundra, CIF or C&F to your port.
• Moisture ceiling and sulphur dioxide limit. Poorti's published flake specification is 10.0% moisture and 180 ppm sulphur dioxide maximum.
• Sulphite labelling: the US FDA requires any sulphiting agent used to be declared on the label if sulphites in the food exceed 10 ppm (ADOGA), so plan your finished-product label around the SO₂ in the flakes.
• Microbiological standard: Poorti's flake specification sets total plate count at 100,000 per g max, coliforms at 100 per g max, and enteropathogenic E. coli and Salmonella absent.
• Allergen statement for the lot, and a gluten test if you will make a gluten-free claim.
• Label language, and any certificate your market requires, named in the enquiry.

Potato flour is packed in the same sack and follows the flakes specification for chemical and microbiological limits; send the mesh you buy to today and the sample is milled to it (the specification). If you want the potato ingredient inside your own branded product, Make and the private-label manufacturing guide cover that route.