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Evaporated Milk & Sweetened Condensed Milk

Evaporated & Sweetened Condensed Milk

Composition, manufacture and quality control for the two classic concentrated milk products

Evaporated milk and sweetened condensed milk are made the same way up to a point — both remove most of the water from milk by vacuum evaporation — then they diverge completely in how they are preserved. Evaporated milk carries no sugar and is sterilised in the can. Sweetened condensed milk is never sterilised; the sugar itself is the preservative. That single difference drives almost everything else about how each is made, what can go wrong, and how it is regulated.

This page sets out the compositional standards, the manufacturing process for each, and the quality defects that matter most — referenced against Codex Alimentarius and UK regulation.

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Services Dairy Science Information

What Distinguishes Them

Codex Alimentarius CXS 281-1971 and CXS 282-1971; UK: Condensed Milk and Dried Milk (England) Regulations 2015 (SI 2015/675)
 Evaporated milkSweetened condensed milk
Preservation methodHeat — sterilised in the sealed canSugar — high osmotic pressure inhibits microbial growth
Added sugarNoneRoughly 40–45% of finished product
Retort/sterilisation after canningYes, in-container (~115–120°C)No — sugar concentration alone preserves it
Shelf life, unopened, ambientLong, but heat-dependent quality risk (see age gelation)Long — often a year or more if sealed
Primary quality riskAge gelation, fat separationSandiness (lactose crystals), age thickening

Composition Standards

Both products are defined by Codex Alimentarius on a solids-not-fat protein basis — minimum 34% milk protein in milk-solids-not-fat for every grade, consistent with the same rule used for milk powders. The UK's Condensed Milk and Dried Milk (England) Regulations 2015, implementing EU Directive 2001/114/EC, apply the identical 34% protein-adjustment rule and closely mirror the Codex compositional table.

Evaporated milks — Codex CXS 281-1971

GradeMilkfatMin. milk solidsProtein in MSNF
Evaporated milkMin 7.5%25%34%
Evaporated skimmed milkMax 1%20%34%
Evaporated partly skimmed milk1–7.5%20%34%
Evaporated high-fat milkMin 15%11.5% (SNF)34%

Sweetened condensed milks — Codex CXS 282-1971

GradeMilkfatMin. milk solidsProtein in MSNF
Sweetened condensed milkMin 8%28%34%
Sweetened condensed skimmed milkMax 1%24%34%
Sweetened condensed partly skimmed milk1–8%24% (20% SNF)34%
Sweetened condensed high-fat milkMin 16%14% (SNF)34%

Sugar content itself is not fixed by Codex to a single figure — it is governed by Good Manufacturing Practice to a minimum that safeguards keeping quality and a maximum above which sugar crystallisation occurs. In practice this settles around 40–45% of the finished product, with the sucrose-in-water-phase ratio the figure that actually matters for preservation (see below).

Note: UK domestic standards prior to EU harmonisation under Directive 2001/114/EC required a higher minimum composition than the current Codex/UK figures above — historically closer to 9% fat and 31% total solids for full-cream evaporated milk and sweetened condensed milk alike. The figures given in this section are the current legal minimums.

Manufacturing Process

Shared first stages

  1. Standardisation — fat and protein adjusted to the target grade, using retentate/permeate/lactose as permitted, without altering the whey-protein-to-casein ratio.
  2. Forewarming (preheating) — the single most important control step for both products. Destroys enzymes and microorganisms (including a significant proportion of spores), sets the heat stability the product will need later, and directly shapes the finished viscosity. Time-temperature combinations range widely in practice — from longer holds at moderate temperature (roughly 85–95°C for several minutes) to short high-temperature treatments; the modern trend favours higher-temperature, shorter treatments, which reduces spore load enough that a less intensive final step is needed.
  3. Vacuum evaporation — concentrated to the target solids in a vacuum pan or multi-effect/TVR evaporator, at low temperature to limit further heat damage.

Evaporated milk — diverges into heat preservation

  1. Forewarming, in practice — commonly around 110°C for half a minute, or a longer hold at roughly 96°C for 10 minutes; the choice sets the casein stability the product carries into sterilisation.
  2. Homogenised (high pressure, commonly in the region of 24,000–30,000 psi) to stabilise the fat and prevent creaming, and to help distribute added fat-soluble vitamin D evenly.
  3. Standardised a second time if needed (fat:SNF ratio, then water to the target total solids), stabilising salts added (e.g. sodium citrate, disodium phosphate, sodium carbonate, checked batch-by-batch), cooled and filled into cans.
  4. Sterilised in-container — a typical cycle runs an 18-minute preheat, 18 minutes at around 116°C, then 18 minutes cooling to around 34°C. This has to achieve commercial sterility against spore-forming organisms, particularly Clostridium botulinum, without over-sterilising to the point of quality loss or coagulating the product — which is why forewarming, homogenisation pressure and mineral salt balance all have to be right before this step, not corrected afterwards.
  5. Agitated/rotated during cooling to control fat separation and even out the Maillard browning that gives evaporated milk its characteristic tan colour and mild caramelised flavour.

Sweetened condensed milk — diverges into sugar preservation

  1. Forewarming, in practice — a shorter, cooler treatment than evaporated milk, typically around 77–82°C for 5 minutes, aimed specifically at preventing age thickening later in storage.
  2. Sugar addition, calculated so the sucrose-in-water-phase ratio comfortably exceeds the minimum needed to suppress microbial growth (commonly worked to a target around 62.5% or higher) while staying below the level at which sugar itself starts to crystallise out of solution (in the region of 67.5g sugar per 100g solution). Sugar can be added dry or as a hot syrup; a dry positive-pressure addition avoids diluting the product with extra water.
  3. Evaporated under vacuum to the target total solids.
  4. Cooled to around 20°C and seeded with fine powdered lactose crystals to control crystallisation (see Sandiness, below). Two methods are used commercially: batch (seed crystals stirred through the whole batch) and continuous (a scraped-surface "votator" shell-and-tube cooler, where a controlled build-up of product on the tube wall itself acts as the seed).
  5. Rapidly cooled with agitation to fix a large number of very small lactose crystals rather than a few large ones.
  6. Canned, filled to the brim to exclude air and discourage mould growth, without retort sterilisation — the sugar concentration itself is the preservation mechanism.

Sugar behaviour during crystallisation

Different sugars have different sweetness and solubility, which matters when seeding and cooling SCM to control crystal size:

SugarRelative sweetness (sucrose=100)Relative solubility
Fructose17374
Sucrose10067
Glucose7460
Maltose32.544
Lactose1616

Lactose is by far the least soluble of the sugars present, which is exactly why it is the one that crystallises out of the concentrated product and has to be managed by seeding and controlled cooling rather than left to nucleate on its own. A supersaturated sugar solution passes through a labile zone (spontaneous, uncontrolled nucleation — large crystals, sandiness risk), a metastable zone (crystals grow on seed already present but new nucleation is unlikely — the zone manufacturers deliberately target), and an undersaturated zone (no further crystallisation) as it cools.

Key Quality Defects

Age gelation (evaporated milk). Progressive thickening or gelling during storage. Governed largely by forewarming intensity and by storage time and temperature — cool, stable storage and correctly set forewarming reduce the risk.
Sandiness (sweetened condensed milk). A gritty, sandy mouthfeel caused by lactose crystals growing too large. Lactose is only partly soluble in the concentrated product, so most of it must crystallise out; the goal is many small crystals, not a few large ones. Controlled by seeding with fine lactose crystals and rapid cooling with agitation — the accepted benchmark for a smooth, first-grade product is keeping crystals below around 10 micrometres.
Microbial spoilage in SCM. Below a critical sucrose-in-water-phase ratio (commonly cited in the region of 62–65%), osmophilic yeasts and moulds can grow despite the sugar. Maintaining the correct sugar-to-water ratio and hygienic filling are the controls, not heat.
Maillard browning (both products). Heat-driven reaction between milk proteins and lactose that darkens colour and changes flavour. Accelerated by higher processing and storage temperatures; expected and characteristic in evaporated milk from sterilisation, but a defect if excessive in storage.
Storage temperature (both products). Both are sensitive at the extremes — low temperatures (near or below 0°C) risk sugar/lactose separation and sandiness in SCM, while elevated storage temperatures (above roughly 25°C) accelerate browning and viscosity change in both. A stable, moderate storage temperature is the simplest and most effective control for either product.
Mould-related coagulation — Aspergillus niger "buttons" (SCM). An air-requiring (aerobic) mould that can contaminate the can headspace. As it grows it produces an enzyme that causes small, localised coagulated "buttons" of product, typically a few millimetres to around 2cm across. Controlled by filling cans to the brim to exclude air and by plant hygiene, not by the sugar preservation mechanism, since the mould is not inhibited by the same osmotic effect that controls bacteria.

Frequently Asked Questions

What is the difference between evaporated milk and sweetened condensed milk?

Both are made by removing most of the water from milk by vacuum evaporation. Evaporated milk has no added sugar and is preserved by in-container sterilisation after canning. Sweetened condensed milk has sugar added to roughly 40–45% of the finished product and is never retorted — it is preserved instead by the high sugar concentration.

Why does evaporated milk sometimes gel or thicken in storage?

This defect, called age gelation, is linked to the forewarming treatment before evaporation and to storage time and temperature. Correct forewarming intensity and cool, stable storage reduce the risk.

What causes sandiness in sweetened condensed milk?

Sandiness is a gritty texture caused by large lactose crystals. Seeding the product with fine lactose crystals and cooling rapidly with agitation produces many small crystals rather than a few large ones, keeping the product smooth.

Disclaimer: This information is provided for general guidance and indicative planning only. While every care has been taken to ensure accuracy, Watson Dairy Consulting (JWC Services Limited, SC246124) accepts no liability for any loss or damage arising from its use. Compositional and process figures are typical ranges and must be verified against the current Codex, EU/UK or destination-market regulation applicable to your product, and against your own plant and analytical data, before being relied upon for specification, design, safety or operational decisions.

References:

  • Codex Alimentarius Commission. Standard for Evaporated Milks, CXS 281-1971 (rev. 1999, amended 2010). FAO/WHO.
  • Codex Alimentarius Commission. Standard for Sweetened Condensed Milks, CXS 282-1971 (rev. 1999, amended 2010). FAO/WHO.
  • Council Directive 2001/114/EC relating to certain partly or wholly dehydrated preserved milk for human consumption, as amended by Directive 2007/61/EC.
  • The Condensed Milk and Dried Milk (England) Regulations 2015 (SI 2015/675), and equivalent Scotland/Wales/Northern Ireland instruments.
  • Dairy Science and Technology, University of Guelph — Concentrated and Dried Dairy Products.

Further reading: John Watson publishes articles on dairy industry topics on LinkedIn. Browse all articles by John Watson on LinkedIn →

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