Food engineering in the industry

These flashcards cover key concepts, definitions, unit operations, industrial examples and emerging technologies mentioned during the "Food Engineering in the Industry" lecture. They target the fundamental knowledge likely to appear in the quiz (pasteurisation vs sterilisation, heat transfer, unit operations) and provide context from real-world applications discussed by the lecturer.

What is the simplest definition of food engineering given in the lecture?

All the processing steps that transform raw agricultural materials into the foods we eat.

What is the #1 reason we process food?

To extend shelf life.

Name two additional reasons (besides shelf life) for processing food.

• Increase variety in flavour, texture, colour and aroma. • Add economic value / meet new market trends.

Which pH value separates ‘low-acid’ from ‘acid’ foods in processing regulations?

pH 4.5

Why are acid foods (pH < 4.5) generally easier to store safely?

Most pathogenic bacteria dislike low pH and grow poorly in acid foods.

Define pasteurisation.

A mild heat treatment (≈60–85 °C, below 100 °C) designed to reduce microbiological load and extend shelf life, especially for low-acid foods such as milk.

Define commercial sterilisation.

A severe heat treatment (typically 121 °C for a set time) that destroys all pathogenic and most spoilage microorganisms and their spores, producing shelf-stable products such as canned baked beans.

Give one key sensory disadvantage of severe thermal processing.

Undesirable changes in flavour, colour or texture (‘cooked’ taste).

What three controllable factors made up the lecturer’s oversimplified model of processing?

Temperature, time and turbulence.

Why is homogenisation used in milk processing?

High-pressure homogenisation breaks fat globules into smaller droplets, preventing cream separation and giving a stable product.

What enzyme (from calf stomach) is traditionally added to coagulate milk during cheese making?

Rennet

In cheese making, what are the two main milk proteins separated into curd and whey?

Curd contains casein; whey contains whey proteins.

State the typical spray-dryer residence time to turn milk droplets into powder.

A few seconds.

Why are infant formula powders technologically challenging and high value?

They must be fortified with 40–50 sensitive nutrients (vitamins, minerals, DHA, etc.) and still meet safety and reconstitution requirements.

What physical property (symbol c_p) tells you how much energy is needed to raise 1 kg of a food by 1 °C?

Specific heat capacity.

Which of the following has the highest specific heat: milk powder, apple, fresh bread, frozen apple?

Fresh apple (because of its high water content).

Define thermal conductivity (k) in the context of food.

A measure of how well a material conducts heat through it.

What are the three basic modes of heat transfer?

Conduction, convection and radiation.

Give one common industrial example of a heat exchanger in food processing.

Plate or tubular heat exchanger used to pasteurise milk or sauces.

What is blanching and why is it used for vegetables?

A short mild heat treatment (≈70–100 °C, 1–15 min) that inactivates enzymes responsible for colour and flavour deterioration without fully cooking the product.

What is the main purpose of evaporation in dairy processing?

To remove water (pre-concentrate milk) before spray drying, reducing energy and transport costs.

What key advantage does freeze-drying have over spray drying for coffee?

Minimal heat exposure, so aroma is better preserved.

List two non-thermal preservation technologies discussed.

High-pressure processing (HPP) and irradiation (gamma or electron-beam).

How much pressure (approx.) is applied in commercial high-pressure processing of foods?

≈400–600 MPa (equivalent to several thousand bar).

Name two commercial Australian products that use HPP (‘cold pressed’) technology.

Examples include Presha-fruit juices and Pressure fruits guacamole/avocado products.

What structural change does pulsed electric field (PEF) cause in microbial cells?

It opens pores in the cell membrane (electroporation), leading to cell death.

State one packaging function besides merely ‘containing’ the food.

Protection from environmental factors (oxygen, light, moisture) OR communication/branding information OR convenience for the consumer.

What term is used for fully automated food factories that can operate with the lights off?

Dark (or black-light) factories.

Which company’s UK facility produces about 3 million cans of baked beans per day?

Heinz (Wigan plant).

What impossible ‘triangle’ was identified for current plant-based meat products?

It is hard to achieve simultaneously: low price, excellent taste, and high nutrition.

What unit operation is most often used to create the fibrous texture in plant-based meat analogues?

High-moisture extrusion.

Why does coconut oil fat in plant-based burgers sometimes give poor cooking behaviour?

It melts too quickly on a hot pan, causing excessive oil release and an unrealistic mouthfeel.

What drying process involves sublimation of ice under vacuum?

Freeze drying (lyophilisation).

Why is irradiation effective yet controversial as a preservation method?

It sterilises at room temperature and low cost, but public perception links it (incorrectly) with radioactivity hazards.

What emerging food manufacturing technique uses computer-controlled deposition of edible ‘inks’?

3-D food printing.