Drop manufacturing is, despite the appearance of consumer-facing simplicity, a substantial industrial process involving controlled extraction, multiple cooking stages, mechanical forming, drying, surface treatment, and packaging. The Dutch industry produces roughly 35,000 tonnes of finished drop per year across the four major makers and a number of smaller specialist producers; the manufacturing technology has evolved substantially since the early twentieth century but the underlying chemistry has been essentially stable since the 1950s. This entry walks through the eight principal production stages, with the practical parameters at which each is conducted.
The reference manufacturer for which the process is most fully documented is Venco, whose Hoogeveen factory has been the subject of several published descriptions over the decades. The processes used at the other major Dutch and European licorice producers are broadly similar, with regional and brand-specific variations principally affecting the exact temperatures, the choice of binders, and the sequence in which flavourings and salt are incorporated. The process described here is representative rather than universal.
Stage 1 — Extract preparation
Drop production begins with licorice extract — the dried concentrated juice of the Glycyrrhiza glabra root. The extract arrives at Dutch factories from suppliers in Iran, Turkey, Uzbekistan, Afghanistan, and (for the higher grades) Calabria, in dried bricks of approximately 25kg each. The bricks are produced by extraction at the source: the licorice roots are washed, chopped, boiled in water for 8–12 hours, the resulting liquid is filtered to remove fibre, and the filtered juice is concentrated by evaporation until it reaches a paste-like consistency, then dried into the brick form.
The extract bricks contain approximately 6–14% glycyrrhizin (depending on grade and source), with the remainder being other plant sugars, tannins, and natural binders. The grade is significant for the eventual product: a lower-glycyrrhizin extract requires more material to achieve the same flavour intensity in the finished candy and produces a slightly different flavour profile. The Dutch industry conventionally uses extract from Iran for everyday products and from Calabria or Turkey for premium and artisanal products.
Stage 2 — Dissolution
The dried extract bricks must be dissolved before they can be incorporated into a finished candy. Dissolution is performed in heated water at approximately 80–90°C, with mechanical stirring, in stainless-steel vessels. The dissolution takes between 4 and 8 hours depending on the extract grade and the desired final concentration. The resulting solution — a dark brown liquid with the viscosity of a heavy syrup — is then filtered to remove any insoluble plant matter that has survived the original extraction.
The filtration is important to the eventual candy's clarity and flavour. Insoluble fibres or proteins surviving from the original root extraction will produce a cloudy or grainy product, and Dutch industrial practice requires successive fine filtration to achieve a clean liquid before the subsequent blending stage.
Stage 3 — Blending
The dissolved extract is blended with the other principal ingredients: the binder (usually gum arabic or modified starch), the sweetener (sugar and glucose syrup), and any flavourings (honey for honingdrop, anise oil for aniseed-flavour products, eucalyptus or menthol for the cough-derivative products). The blending occurs in heated mixing vessels at 70–80°C, with the order of addition determining the final texture. For hard drop, the binder is added first to produce a stable solution; for soft drop, the binder is added in a higher proportion and at a lower temperature to retain more elasticity.
Salt is added at this stage for products containing it. Sodium chloride (table salt) is added directly to the blend in solution. Ammonium chloride (the salmiak compound, treated separately under salmiak) is added either in solution or, for some surface-coating applications, as a fine powder added at a later stage. The final ammonium chloride concentration in the finished product determines the salt grade: 0% for sweet drop, 0.5–2% for lightly salted, 2–4.49% for salted, 4.5–7.99% for dubbelzout.
Stage 4 — Cooking
The blended mixture is then cooked to remove water and concentrate the syrup. Cooking is performed in stainless-steel vacuum cookers at temperatures of 105–125°C and reduced pressure (typically 200–400 millibar absolute). The vacuum allows the cooking to proceed at lower temperatures than would be required at atmospheric pressure, which preserves the licorice extract's flavour profile and prevents excessive caramelisation of the sugar. The cooking continues until the syrup reaches the target solids content — typically 75–80% for hard drop, 70–75% for soft drop.
The cooking stage is critical for the final product's texture. Overcooking produces a hard, brittle candy; undercooking produces a sticky, unstable one. The Dutch industry has, over decades, standardised the cooking protocols for each product type, and the major manufacturers' production lines are tightly controlled to maintain consistent texture across batches.
Stage 5 — Casting / forming
The cooked syrup is then formed into individual pieces by one of two principal methods. For most lozenge-style products, the syrup is poured into starch moulds — open trays of finely-ground starch in which the desired shape (ruit, munt, kat, ovaal) has been pressed by a pattern board. The starch absorbs minor moisture and provides the mould without requiring removal of the candy from a hard form. After the syrup has set, the candies are removed from the starch, the starch is brushed off, and the starch trays are reused.
For some products — particularly the soft drop varieties and the modern Autodrop range — the syrup is instead extruded through a die and cut into individual pieces. The extrusion method is faster and produces more uniform pieces, but cannot easily produce the more elaborate figural shapes and is limited to relatively simple geometries. The classical Dutch shape vocabulary (treated under drop shapes) is mostly produced by the starch-mould method.
Stage 6 — Drying
The freshly-cast candies must be dried to stabilise their texture and extend shelf life. Drying is performed in temperature- and humidity-controlled rooms or tunnels at 30–35°C and 30–45% relative humidity, for periods of between 8 hours (for soft drop) and 48 hours (for hard drop). The drying conditions are critical: too rapid drying produces surface cracks and uneven shrinkage, too slow drying produces sticky and unstable candies.
The drying stage is the longest single stage of production by elapsed time, and substantial floor space is dedicated to it in the major Dutch licorice factories. The Hoogeveen Venco facility, for example, has approximately 2,000 square metres of climate-controlled drying space, through which cast candies move on slow conveyor systems that allow precise control of the drying environment.
Stage 7 — Surface finishing
Once dried, many drop products receive a surface treatment. The most common surface finishes are:
- Gloss — application of a thin layer of edible wax (carnauba or beeswax) to produce a glossy surface and reduce moisture absorption.
- Salmiak coating — application of fine ammonium chloride powder for products like schoolkrijt, where the salmiak is a surface treatment rather than a base ingredient.
- Salt coating — application of sodium chloride for products requiring a salt-crystal surface.
- Sugar dust — application of fine sugar for some sweet products, particularly children's-market lines.
The surface finish is applied in rotating drums or coating pans, with the candies tumbling gently while the coating material is sprayed or sprinkled onto them. The coating drums operate continuously and can process several thousand kilograms of finished candies per shift.
Stage 8 — Packaging
The final stage is packaging. The vast majority of Dutch drop is packaged in flexible plastic pouches of 200g, 250g, or 500g, with smaller specialty bags (100g) for premium products and larger bags (1kg) for institutional sales. Some specialty products — particularly the higher-grade dubbelzout lines — are packaged in tinplate boxes that protect the candies from moisture and light. The classical hexagonal honingdrop tins of Venco and Klene are examples of this packaging form.
The packaging operation is highly automated. Modern Dutch licorice factories use form-fill-seal machinery that produces, fills, and seals the bags in a continuous operation at rates of up to 200 bags per minute. The packaged products are then case-packed for retail distribution and palletised for shipping. The total elapsed time from extract dissolution to packaged finished candy is typically 3–7 days, depending on the product type and the drying schedule.