At 6 a.m. a tanker of raw milk pulls into a dairy outside Mbarara, Uganda. By early afternoon the same milk has been tested, cooled, clarified, standardised for fat, pasteurised at 72 °C for 15 seconds, chilled again and sealed into pouches carrying a lot code and a use-by date. Each step was chosen for a reason, and each one is checked and recorded. If you have ever asked what is food technology, this line is a good answer: science and engineering put to work so that safe, consistent food reaches people at a price they can pay.
In short
- Food technology is the application of food science and engineering to process, preserve, package and manufacture food safely, consistently and at scale.
- Food science explains why food behaves as it does; food technology uses that knowledge to decide how to make it.
- Every food process is a chain of unit operations, such as cleaning, size reduction, mixing, separation, heating, cooling and packing, drawn as a process flow diagram.
- Preservation works by killing microbes (mainly heat), slowing them (cold, drying, acidity, preservatives) or keeping them out (packaging). Most foods combine several of these.
- Hygiene and quality systems built on Codex Good Hygiene Practices and HACCP keep every batch safe.
What is food technology?
Food technology is the application of food science and engineering to process, preserve, package and manufacture food. It turns knowledge about how food behaves into recipes, machines, processes and controls that work at factory scale.
Food science asks why: why does milk sour? Food technology asks how: how do we heat thousands of litres of milk an hour so that every drop gets the right time and temperature? For the science side, Introduction to Food Science covers the chemistry and microbiology that food technology builds on.
| Food | Food science asks | Food technology asks |
|---|---|---|
| Milk | Which bacteria grow in milk, and how fast at different temperatures? | Which heat treatment, cooling and pack give safe milk with the shelf life the market needs? |
| Bread | How do gluten proteins hold the gas made by yeast? | How do we mix, prove and bake thousands of loaves an hour to the same volume and weight? |
| Jam | Why does a high sugar content stop most microbes growing? | What boiling time, sugar content and filling temperature give a safe jam with a good set? |
| Crisps | Why do frying oils oxidise and go rancid? | Which frying conditions, nitrogen-flushed pack and barrier film keep crisps fresh for months? |
Almost every decision serves five goals: safety, preservation, quality, convenience, and consistency at a sensible cost. Safety comes first. The goals often conflict: heating juice harder makes it keep longer but changes its flavour, colour and vitamin C content. Much of the job is finding the right balance.
What are unit operations in food processing?
Unit operations are the basic processing steps from which every food process is built, such as cleaning, size reduction, mixing, separation, heating, cooling and packing. Each follows the same principles whatever food passes through it: a plate heat exchanger heats milk and fruit juice by the same physics.
| Group | Unit operations | Everyday example |
|---|---|---|
| Preparation | Cleaning, sorting, grading, peeling | Washing and optical sorting of peas |
| Size reduction | Cutting, slicing, milling, homogenising | Milling wheat into flour; homogenising milk |
| Mixing and forming | Mixing, kneading, emulsifying, moulding, extrusion | Breakfast cereal rings from an extruder |
| Separation | Sieving, filtration, centrifugation, pressing, membrane filtration | Separating cream from milk |
| Heating | Blanching, pasteurisation, sterilisation, baking, frying, evaporation, drying | Frying crisps; spray drying milk powder |
| Cooling | Chilling, freezing | Quick freezing peas, then storing them at −18 °C or below |
| Packing and handling | Filling, sealing, labelling, conveying | Filling and sealing yoghurt pots |
A process flow diagram lists every step in order, from receiving raw materials to dispatch. It is the backbone of a HACCP plan, and the Codex HACCP steps include confirming it on the factory floor. Here is the flow for the pouch milk in the opening example.
- Receive and test: check temperature, screen for antibiotic residues, run quality tests.
- Cool and store: hold the milk cold in insulated silos.
- Clarify and separate: a centrifuge removes sediment and splits off the cream.
- Standardise: recombine cream and skim milk to the target fat content.
- Homogenise: break fat globules small so no cream layer forms.
- Pasteurise: 72 °C for 15 seconds; a flow diversion valve sends back any milk that did not reach temperature.
- Cool: to 5 °C or below.
- Fill, seal and code: print the lot code and use-by date on every pouch.
- Dispatch chilled: record which lots went to which customer, so a recall can be fast.
How does food technology preserve food?
Food technology preserves food in three ways: by killing microorganisms and inactivating enzymes, mostly with heat; by slowing growth with cold, drying, acidity, preservatives or fermentation; and by keeping contamination out with packaging. Most foods combine several, an approach called hurdle technology.
Two measurements sit behind many decisions. Water activity (aw) is a measure of how much of the water in a food is available to microbes, on a scale from 0 to 1.0. Most bacteria stop growing below about 0.91, most yeasts below about 0.88 and most moulds below about 0.80, and microbial growth effectively stops below about 0.60. pH measures acidity: at pH 4.6 or below, spores of Clostridium botulinum cannot grow. Foods above pH 4.6 with an aw above 0.85 are called low-acid foods, and if they are to be stored at room temperature they need a severe heat process called a botulinum cook.
| Method | How it works | Typical conditions | Examples |
|---|---|---|---|
| Pasteurisation | Kills vegetative pathogens; spores survive, so chilling or acidity is also needed | Milk: 72 °C for 15 s (HTST) or 63 °C for 30 min (LTLT) | Fresh milk, juices |
| UHT, aseptic packing | Destroys spores; sterile product filled into sterile packs | About 135 to 150 °C for a few seconds | Long-life milk |
| Retorting (canning) | Sealed pack heated under pressure | Low-acid foods: at least F0 3 min | Canned beans, fish |
| Chilling | Slows microbes; kills almost nothing | 5 °C or below | Ready meals |
| Freezing | Stops microbial growth | −18 °C or below | Frozen peas |
| Drying, salting, sugaring | Lowers water activity | Below 0.91 aw stops most bacteria; below about 0.60, all growth | Milk powder, jam |
| Acidification, fermentation | Lowers pH | pH 4.6 or below for acid foods | Pickles, yoghurt |
| High pressure processing (HPP) | Pressure damages vegetative cells; spores survive | Typically 400 to 600 MPa for a few minutes, chilled | Juices, dips (kept chilled) |
Vegetative cells are actively growing microbes; spores are tough, dormant forms made by some bacteria that survive far more heat. HTST means high-temperature short-time, LTLT low-temperature long-time, and UHT ultra-high temperature; aseptic packing fills sterile product into sterile packs in a sterile zone. A D-value is the time at a set temperature that kills 90 % of a population. F0 expresses the killing power of a heat process as equivalent minutes at 121.1 °C.
Worked example
A cannery packs peaches (pH about 3.8) and green beans in brine (pH about 5.6, aw close to 0.99).
Peaches are an acid food (pH 4.6 or below), so C. botulinum cannot grow. The heat process only needs to destroy yeasts, moulds and acid-tolerant bacteria, often at or around 100 °C.
Green beans are a low-acid food (pH above 4.6, aw above 0.85). They need a botulinum cook, a 12D process that reduces C. botulinum spores by a factor of 10¹². With a D-value at 121.1 °C of about 0.21 min, 12 × 0.21 min = 2.52 min, so the accepted minimum is F0 = 3 min at the slowest-heating point of the can, reached in a retort under pressure. Many products receive more to control heat-resistant spoilage spores.
What does food packaging do?
Packaging contains food, protects it, carries information and adds convenience. It rarely makes food safer on its own; it keeps food in the condition processing created. Packaging protects against:
- Microbes: a sealed can or aseptic carton keeps a sterile product sterile.
- Moisture: barrier films keep crisps crisp and stop bread drying out.
- Oxygen and light: barrier layers and opaque packs slow rancidity and light-induced off-flavours.
- Damage, pests and tampering: trays, cases and tamper-evident closures.
Modified atmosphere packaging (MAP) replaces the air in a pack with a gas mix, often nitrogen and carbon dioxide, to slow spoilage. Low-oxygen packs do not control every hazard, though. Non-proteolytic C. botulinum can grow without oxygen from about 3 °C, so chilled vacuum and MAP foods need carefully set shelf lives.
Labels matter as much as barriers. The Codex General Standard for the Labelling of Prepackaged Foods (CXS 1-1985) sets the core information, including the ingredients list, net contents, lot identification, date marking and declaration of priority allergens: cereals containing gluten, crustaceans, eggs, fish, milk, peanuts, sesame and specified tree nuts, plus sulphites at 10 mg/kg or more. A use-by date relates to safety; a best-before date relates to quality. Countries build on these rules, so check your national legislation.
How do food factories keep products safe and consistent?
Factories keep products safe and consistent through Good Manufacturing Practice, a HACCP-based food safety system and quality control checks on raw materials, the process and finished products.
Good Hygiene Practices (GHPs) are the everyday conditions for safe production: hygienic premises and equipment, cleaning, pest control, personal hygiene, potable water, supplier control, allergen management and training. The Codex General Principles of Food Hygiene (CXC 1-1969, revised 2020) set them out and also stress food safety culture. HACCP (Hazard Analysis and Critical Control Point) is built on top: a team analyses the hazards in a specific process and sets validated critical limits at critical control points, the steps where control is essential to prevent, eliminate or reduce a significant hazard to an acceptable level, such as the pasteuriser.
Many sites are certified to ISO 22000:2018 or to a scheme benchmarked by the Global Food Safety Initiative (GFSI), such as FSSC 22000, BRCGS, SQF or IFS. On the line, quality control means checkweighers, metal detectors tested with test pieces at set intervals, temperature records, label checks at every changeover and laboratory tests. Our Introduction to Food Technology course ends inside the factory with these controls.
Frequently asked questions
Is food technology the same as food science?
No, but the two overlap. Food science studies what food is made of and why it behaves as it does, drawing on chemistry, microbiology, physics and nutrition. Food technology applies that knowledge, together with engineering, to process, preserve, package and manufacture food at scale. A food scientist explains why a cut apple turns brown; a food technologist designs the dip, pack and chilled storage that keep packed apple slices pale for days.
What does a food technologist do day to day?
It depends on the role. Typical tasks include writing product specifications, approving suppliers, checking labels and allergen declarations, investigating complaints, running factory trials of new recipes, reviewing HACCP records and supporting audits. Roles range from production and quality assurance to product development, engineering and auditing. The common thread is knowing exactly how a product is made and why each step matters.
Does processing make food less healthy?
Not by itself. Processing ranges from washing salad and freezing peas to making confectionery. Some processing makes food safer, such as pasteurising milk. Some protects nutrients, such as freezing vegetables soon after harvest. Some makes raw materials usable at all, such as milling wheat. Heat can reduce vitamins such as vitamin C and thiamin, but the nutritional value of a processed food depends mostly on its recipe, especially its salt, sugar, fat and fibre.
What is the difference between pasteurisation and sterilisation?
Pasteurisation is a mild heat treatment, such as 72 °C for 15 seconds for milk, that kills vegetative pathogens but leaves bacterial spores alive, so the food also needs chilling or acidity. Sterilisation of food usually means commercial sterility: enough heat, such as UHT at about 135 to 150 °C for a few seconds or a retort process of at least F0 3 minutes for low-acid foods, that no microbe can grow during normal storage at room temperature.
Why is pH 4.6 so important in food technology?
Spores of Clostridium botulinum, the organism that produces botulinum toxin, cannot grow at pH 4.6 or below. Foods above pH 4.6 with a water activity above 0.85 are classed as low-acid foods. If they are sealed and stored at room temperature, they need a validated botulinum cook in a retort or a UHT plant. Acid foods, such as most fruits and pickles, can be made shelf-stable with much milder heat.
Next step. Introduction to Food Technology follows food from raw material to finished pack: why food spoils, the core unit operations, pasteurisation, canning and UHT, chilling, freezing, drying and high pressure, packaging, new product development and GMP, with guided tours of bread, milk and crisp production. It ends with a proctored final assessment and an ASC certificate. You can also see all eleven food science and technology courses.
Sources. P. J. Fellows, Food Processing Technology: Principles and Practice, 5th edition (Woodhead Publishing, 2022); Norman N. Potter and Joseph H. Hotchkiss, Food Science, 5th edition (Chapman & Hall, 1995); Gordon L. Robertson, Food Packaging: Principles and Practice, 3rd edition (CRC Press, 2012); Codex Alimentarius Commission, General Principles of Food Hygiene, CXC 1-1969 (revised 2020), and General Standard for the Labelling of Prepackaged Foods, CXS 1-1985; World Health Organization, Five Keys to Safer Food Manual (2006).
This article is general guidance on food technology principles and is not a substitute for the applicable standard, your national legislation or the advice of a qualified food safety professional.