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Frequently Asked Questions

A collection of answers to some of the questions Learners asked about this Week's content.

We’ve collected together some of the questions Learners asked about this Week’s content when the course was last run and provided some answers here. You may have different questions. If so, do post them in the comments section below. Your fellow Learners will have their own views and may well be able to point you in the direction of further information.

2.2. The benefits and drawbacks of food processing

Processed foods contain a lot of additives or ‘chemicals’ – is this bad or good?
  • Firstly, the ‘chemicals’ term can mislead us – everything about a food is a chemical, whether it be a natural ingredient or an additive.
  • ‘Food additives’ is a common term for wide range of compounds added to food to perform a specific purpose, which could include to add colour, preservatives to improve shelf-life, sweeteners to replace sugar, etc. The intended purpose is to benefit the consumer in terms of food quality.
  • European and National Food Safety and Standards Agencies assess the safety of food additives according to the latest scientific evidence. These review the science of additives and ensure that action is taken where necessary and enforce legislation to ensure food additives are used safely.
  • In a European context, approved food additives are given an E number. E numbers are shrouded in negative opinion; however, they include many natural chemical compounds, like vitamin C as well as man-made chemical compounds like artificial sweeteners.
What about the disadvantages?
  • Increasing food availability and convenience through preservation, packaging and transportation is listed as a benefit, but can have its disadvantages. For example, the increase in food miles and the loss of our connection to local, seasonal food products, especially fruits and vegetables.
  • ‘Use By’ and ‘Best Before’ dates are a product of our better control and knowledge of food preservation through food processing and use of additives. However, these have had the unintended consequence of increasing food waste since we tend to trust the labelled date rather than our own senses in assessing whether a product is safe to eat. There is also widespread confusion about what ‘Use By’ and ‘Best Before’ dates actually mean.

2.3. Do the positives outweigh the negatives?

Food miles and the transport of food globally have both positive and negative aspects?
  • Yes. There is a balance of positives and negatives in the use of food processing to allow food transportation.
  • Transporting produce provides variety of foods and access to nutrition. This is a benefit to food security.
  • Negatives can include the environmental impact of transportation.
Mass production in agriculture causes concern. How is this related to food processing?
  • This course doesn’t cover agricultural production methods but there is a link to food processing in so far as efficient food processing and the delivery of consistent food product quality to consumers does rely on consistent raw agricultural products that meet specific quality standards.
  • For example, bread flour for commercial bread production needs wheat grain with specific protein content, enzyme activity and other quality parameters. Bread is a staple product and consumes large quantities of wheat. This relies on farmers growing specific varieties of wheat at high yield, which has led to the focus on mass production.

2.4. Homogenisation

How is the combination of homogenisation and pasteurisation done?
  • Pasteurisation is a process to make milk safer and to increase shelf-life. Pasteurisation does not kill all micro-organisms but is intended to kill some bacteria and make some enzymes inactive.
  • Homogenisation is not carried out for safety reasons, but rather for consistency and taste. For large-scale dairy production, homogenisation allows mixing of milk from different herds without issue.
  • If combined, pasteurisation is typically done first before homogenisation. In the example of milk, the heat from pasteurisation makes fat molecules easier to break down for homogenisation.

2.6. Pasteurisation

How is the food heated?
  • The most common way to heat during pasteurisation is through plate heat exchangers. The liquid (usually low-viscosity) flows continuously from the tank through a series of thin plates that heat up the liquid to the appropriate temperature. The liquid flow system is set up to make sure that the liquid stays at the pasteurisation temperature for the appropriate time before it flows through the cooling area of the pasteuriser.
Does pasteurisation protect us from bovine TB (tuberculosis)?
  • Before the advent of pasteurisation, bovine TB was a public health threat with a link, in some cases, to the consumption of infected milk.
  • Pasteurisation does reduce this risk considerably by killing the bacteria that are responsible for the disease, and the pasteurisation of milk and other dairy products has been important in preventing the spread of bovine TB to humans.
  • Pasteurisation is not relied on alone for the control of TB. For many years, bovine TB in domestic cattle herds has been carefully monitored and controlled through whole herd skin testing, slaughter surveillance and monitoring the movement of animals between herds.

2.8. Canning

What effects do epoxy resin and bisphenol A have on our health?
  • Most epoxy coatings are synthesised from bisphenol A (BPA).
  • Small amounts of BPA can be transferred from packaging into food and drinks; however, the level of BPA found in food is not considered to be harmful by regulators, although migration limits are often stipulated.
  • Manufacturers of cans and food companies do have alternatives to replace BPA-based epoxy coatings, as well as BPA capturing systems and top coatings. Most of these alternative coatings are more expensive than epoxy coatings but manufacturers are moving away from BPA.
  • Ongoing research in the USA is looking at the long-term effects of exposure to BPA to examine any link to cancer risk.
How long can spam (meat) stay in a can?
  • Spam is a brand of canned cooked pork that became popular after its use during World War II.
  • The shelf-life of canned meats will depend on how they have been stored. They are marked with a ‘Best Before’ date, so can be safely eaten beyond this date as long as the can is undamaged and has not been exposed to extremes of heat and/or humidity. This could be 2-5 years under correct storage conditions.
  • It is best to eat your cans of meat within the Best Before date. If the top of the can is rounded and dome shaped instead of flat across, do not eat the contents. Be cautious about dented cans, and if you see any leaks or rust it is best to discard.
What effect does the lining have on recycling the metal can?
  • The lining does not prevent cans being recycled. The coatings melt off when the cans are melted in blast furnaces to cast them into metal to be reused for new products.

2.13. Summary

What is the difference between pasteurisation, sterilisation and UHT?
  • Pasteurisation is a controlled heating process used to eliminate any dangerous pathogens that may be present in milk, fruit-based beverages, some meat products, and other foods which are commonly subjected to this treatment. Foods are heated to the minimum temperature required to deactivate specific micro-organisms or enzymes in order to minimise any quality changes in the foods themselves. Pasteurisation is generally carried out at temperatures 100°C.
  • Sterilisation is the destruction of ALL living micro-organisms, and can be achieved by moist heat, dry heat, filtration, irradiation, or by chemical methods. It requires higher temperatures than pasteurisation: 120°C is applied for a period long enough to kill all micro-organisms and their spores. Since bacteria do not survive sterilisation, sterilised products have a much longer shelf life than pasteurised products, but the quality of the product is lower than a pasteurised product.
  • UHT (Ultra-high temperature sterilisation) involves heat treatment of 140°C applied for a very short time; it is especially applicable to low viscous liquid products like milk and achieves sterilisation without the same level of impact on product quality.
© EIT Food
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How Food is Made. Understanding Food Processing Technologies

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