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Food technology Flashcards

(59 cards)

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1
Q

What are the intrinsic factors in food microbiology

A

Intrinsic factors are properties of the food itself that affect microbial growth, including nutrient content, pH, redox potential, water activity, natural antimicrobials, and mechanical barriers.

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2
Q

Why is water activity (aw) important in food preservation

A

Water activity measures how efficiently water can participate in chemical or biological reactions.

Lowering aw reduces microbial growth and is a key method of preservation (e.g., drying, salting).

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3
Q

What is food technology?

A

Food technology is the study of how different foods can be used and made into food products from production to consumption

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4
Q

What is food chain management?

A

Food chain management involves the management of all activities involved in the production, transformation, storage, distribution and the holistic farm to table approach.

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5
Q

What is the main aim of food preservation

A
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6
Q

What is food processing

A
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7
Q

What is the role of the vet in food technology

A

Inspection of animal origin food establishments.

Microbiological testing.

Legislation.

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8
Q

How does pH influence microbial growth?

A

Most microorganisms grow best at pH 6.6–7.5.

Foods with low pH (<4.0), like pickles, inhibit many spoilage microorganisms.

Buffered foods tend to resist changes in pH (meats are more highly buffered than vegetables due to their various proteins).

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9
Q

What is a mechanical barrier for microbial invasion

A

skin

e.g. fermented meat products

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10
Q

What is the ideal temperature for Psychrotrophs, Psycrophiles, Mesophiles and Thermophiles?

A
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11
Q
A
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12
Q

What is the Z value in thermal processing?

A

The Z-value is the temperature change needed to alter the D-value by a factor of 10.

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13
Q

How does Modified Atmosphere Packaging (MAP) inhibit microbial growth?

A

MAP uses gases like carbon dioxide (CO₂) to inhibit microbial growth by creating unfavorable conditions.

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14
Q

Why is relative humidity important in food storage?

A

Low relative humidity prevents surface spoilage by moulds, yeasts, and bacteria, while high humidity can promote microbial growth.

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15
Q

What is food spoilage?

A

Food spoilage refers to changes in food making it unacceptable to consumers due to smell, taste, appearance, or texture.

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16
Q

Why is food rejected as spoiled?

A
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17
Q

What are organoleptic changes?

A
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18
Q

What are chemical changes?

A
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19
Q

How can physical damage lead to food being rejected as spoiled?

A
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20
Q

What is freezer burn?

A

Freezer burn happens when frozen food loses moisture due to poor packaging or wrapping.

Water molecules migrate from the food to colder areas of the freezer, causing dehydration and texture/flavour changes

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21
Q

Give examples of foods that can spoil due to over-ripening

A
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22
Q

What is contamination with chemical agents?

A

Contamination occurs when chemicals enter food through polluted air, water, or soil.

In the food industry, this often happens from cleaning agents used in processing environments

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23
Q

What are the benefits of fermenting meat?

A

Meat fermentation is one method of preservation

Stable and Highly nutritious food.

Extended shelf-life.

Safe product if manufactured and handled correctly.

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24
Q

What is the role of nitrites/nitrates in meat curing?

Study These Flashcards
A

Nitrites/nitrates suppress Gram-negative bacteria, prevent decolorization, and inhibit oxidative rancidity.

25
What is the role of lactic acid in fermented sausages?
Reduces water-binding in meat proteins Speeds up the drying process
26
What does the speed of fermentation depend on?
27
What microorganisms are commonly used as starters for fermentation
Lactobacillus plantarum, Pediococcus acidilacti, and Micrococcus spp.
28
What is ripening in fermentation
Microbial proteinases hydrolyse (break down) proteins into amino acids and other compounds, enhancing flavour and texture
29
What is the process of creating fermented sausages?
1. Raw Meat + Fat – Contains natural microflora (incl. pathogens, LAB, micrococci). 2. Mince – Increases surface area for microbial action and improves texture. 3. Mix Ingredients – Add salt, nitrate/nitrite, and fermentable carbs. 4. Add Starter – Lactobacillus and Pediococcus produce lactic acid; Micrococcus converts nitrate to nitrite. 5. Pack into Casings – Traditionally animal intestines; now often cellulose/collagen. 6. Ferment – LAB convert carbs to lactic acid, lowering pH. 7. Dry & Ripen – Controlled drying reduces water, while fat/protein breakdown adds flavour
30
What microbial factors contribute to safety of fermented sausages?
Low pH (lactic acid production) and reduced water activity (drying and salt addition).
31
What are common microbiological problems in fermentation of sausages?
32
What is the minimum heat process for low acid canned foods?
thermal process achieving a 12-log (decimal) reduction of Clostridium botulinum. At 121°C, the D-value = 0.21 min, so minimum time = 12 × 0.21 = 2.52 min
33
Why can spoilage of canned foods occur?
34
How does smoking preserve food?
Smoke contains antimicrobial substances like formaldehyde, phenols, and methanol which are highly inhibitory to microorganisms
35
What is yoghurt and what are the main types?
36
What is the process of creating yoghurt
1. Raw milk – Source of natural microorganisms. 2. Add solids – Increases solids-not-fat (SNF) content. 3. Homogenisation – Reduces fat globule size. 4. Heat treatment – Kills pathogens, boosts culture activity. 5. Cooling & starter addition – Add S. thermophilus & L. bulgaricus. 6. Incubation – Culture grows, pH drops to 4.4–4.6. 7. Packaging – Either before or after incubation (stirred or set). 8. Cooling & storage – Stops fermentation and preserves product
37
What is Modified Atmosphere Packaging (MAP)?
A preservation method using gases like carbon dioxide (CO₂) to inhibit microbial growth.
38
Why does milk for yoghurt production need to be free from antibiotic residues?
The culture will not multiply in the presence of antibiotics, the pH will not drop and the yoghurt will not set
39
What starter cultures are used to make yoghurt and how do they work?
By fermenting milk with Streptococcus thermophilus and Lactobacillus bulgaricus, converting lactose to lactic acid.
40
How is cheddar cheese produced (process)?
1. Raw Milk – Base ingredient containing natural microbes (pH ~6.7). 2. Pasteurisation – Heat to 72°C for 15 sec to kill pathogens. 3. Starter Addition – Lactococcus lactis added to ferment lactose. 4. Incubation – Lactic acid forms, lowering pH. 5. Rennet & Coagulation – Milk forms curd; cut to release whey. 6. Scalding – Continued heating to reduce moisture & increase acidity. 7. Cheddaring – Curd is stacked, pressed, and flipped to drain whey. 8. Milling & Salting – Curds chopped; salt added for preservation & flavour. 9. Moulding & Pressing – Shaped into blocks; excess whey removed. 10. Ripening – Enzymes break down proteins to develop flavour. 11. Packaging & Storage – Cheese is wrapped and stored for maturation
41
Why is pasteurisation crucial in cheese production?
It destroys pathogens and spoilage organisms, ensuring product safety.
42
What are some common microbial problems in cheese?
Blowing - Early due to coliforms. - Late due to gas producing Clostridia. Mould growth. Bacteriophages attacking starter. Poor hygiene or unpasteurized milk can lead to Salmonella, E. coli, or Listeria monocytogenes contamination.
43
How can hygiene be monitored?
44
What can be monitored at different stages of production?
45
What does microbial criteria consist of?
46
What is the purpose of microbiological criteria in food?
To assess food safety by specifying limits for pathogens, spoilage organisms, or indicators.
47
What are sampling plans?
48
What is a two-class sampling plan?
A method to decide food lot acceptance based on limits (m) and permissible number of defective samples (c).
49
What additional parameter does a three-class sampling plan include?
An upper limit (M) for microbial counts.
50
When do you use a two-class vs three-class sampling plan?
51
How is shelf-life of a product evaluated?
Monitor changes in flavour, aroma, appearance, and texture Assess microbial growth (pathogens, spoilage, indicator bacteria) Store at specified and abuse temperatures to determine limits
52
What is challenge testing in food microbiology?
Testing food products by inoculating pathogens and monitoring their growth, survival, or death under storage conditions.
53
What are extrinsic factors in food microbiology
Extrinsic factors are environmental factors that influence microbial growth, including temperature, humidity, atmosphere, and storage time.
54
What is the D value in thermal processing?
The D-value is the time required to kill 90% of a microbial population at a specific temperature.
55
What determines oxidation/reduction?
The characteristic O/R potential of the original food. The poising capacity; that is, the resistance to change in potential of the food. The oxygen tension of the atmosphere around the food. The access that the atmosphere has to the food. Microorganisms affect the Eh of their environments during growth just as they do pH.
56
What is thermal processing of 1D-4D
57
What is the significance of redox potential (Eh) in microbial growth?
Eh measures the ability of a substrate to gain or lose electrons. Aerobic microbes require positive Eh (oxidized), while anaerobes need negative Eh (reduced).
58
What do microorganisms of importance to food require to grow and function normally
59
name some natural antimicrobial substances

JORGE VPH (39 decks)

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