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Unit 2: MINIMALLY PROCESSED FOODS
1.- WARMING UP. Pair Work. In pairs, answer the following questions:
a) What do you understand by Minimally Processed foods? Can you think of an example of a minimally processed food?
b) What are some of the reasons for the increase in demand and consumption of MP foods? What do YOU think? Are you also interested in them? Why / why not?
c) Minimally Processed Foods is not the only way to refer to these fresh-like products.
From the box below, highlight all those equivalent terms used in the definitions of MPF.
Partial preservation treatment – Invisible processing – Fake processed foods – High-moisture shelf-stable foods – Partially processed foods – Ready-to-eat Foods -
2.- VOCABULARY. Match the words below to the pictures:
husking - chopping - hurdles - peeling - coring - slicing - freezing - blanching - dipping
3.- SPOT THE CONTENT MISTAKES. Have a look at the table below and find out what cells have been misplaced.
PreservationCagegory
Raw Minimally Processed
(refrigerated)
Cold Preserved
Irradiated Dehydrated Heat Preserved
Product quality
Fresh Slightly modified freshness
Slightly modified freshness
Fresh-like Slightly to fully modified freshness
Fully modified freshness
Preservation method
Usually does not require preservation methods
Requires dehydration
Requires cold preservation (freezing or refrigeration)
Requires irradiation (pasteurization)
Requires minimal preservation methods
Requires heat preservation
Storage and shelf life
Requires refrigeration
May or may not need refrigeration
Must be frozen or refrigerated
Requires refrigeration or room temperatures
Usually shelf-stable at room temperature
Shelf-stable at room temperature
Packaging May or may not need packaging
Requires hermetically sealed packaging
Requires packaging
Requires packaging
Requires packaging
Requires packaging
4.- READING COMPREHENSION. Read the following text on the evolution of the definition for minimally processed foods (MPF). Then, in pairs, discuss what the main differences are and choose the definition YOU like best.
Author(s) Year DefinitionRolle and Chism
1987 Includes all the operations (washing, selection, peeling, slicing, etc.) that must be carried out before blanching in a conventional processing line that keep the food a living tissue.
Shewfelt 1987 Includes meat and fresh products, as well as any process that adds some value to the product compared to conventional food preservation processes (i.e., chopping, husking, coring, low level irradiation, and individual packaging).
Huxsoll and Bolin
1989 Includes products that maintain their attributes and quality similar to those of fresh products. In some cases a minimally processed product is a ‘raw’ food and the tissue cells are alive; however, these characteristics are not necessarily required if food freshness is maintained.
Wiley 1994 Includes products that contain live tissues or those that have had slight modifications to their freshness condition but have kept their quality and character similar to those of fresh products.
Ohlsson 1994 Includes those procedures that cause fewer possible changes in the food quality (keeping their freshness appearance), but at the same time provide the food enough useful life to transport it from the production site to the consumer.
Source: ?????? (BiB. UdL: 664 FOO) page 183
5.- DRAG & DROP. Fill in the table below on Applications of Minimal Processing Methods.
1. Most fresh foods 2. Fresh meat and fish 3. Foods and beverages
4. Bulk-storage of fresh fruits and vegetables 5. Fresh vegetables
6. Fresh meat and fish, prepared foods, baked goods, fresh fruits and vegetables
7. many products, particularly fresh fruits, poultry, and spices
8. Dry, frozen, semimoist, and minimally processed foods
9. Fruits and vegetables (sliced and purées) 10. Minimally processed fruits
11. Many liquid products, particularly fruits
12. Many products, especially finished meals 13. Dairy products, sausages
14. Many products, currently fruits
PROCESS APPLICATION MECHANISMControlled-atmosphere storage (CAS):
4 Antimicrobial effect (inhibition of microorganisms); altered respiration rates in fruits and vegetables
New Packaging Technologies:Modified atmosphere packaging (MAP) and active packaging
Edible films
• 6
• 8
Antimicrobial effect (inhibition of microorganisms); altered respiration rates in fruits and vegetables
Protection against oxygen intake, moisture and flavour loss, and superficial contaminants
Postharvest treatments:Chlorinated water soakingReducing agentsPreservativesDivalent ions
5 - Antimicrobial effect- oxidation prevention- antimicrobial effect- improved texture
Clean-room technologies 2 Reduced levels of environmental microorganisms
Protective microbes(lactic acid and bacteria)
13 Release by the protective microbes of bacteriocins that reduce levels of undesirable microorganisms; lactic acid production
Enzyme use 3 Antimicrobial effectNatural antimicrobials 10 Antimicrobial effect (molds
and yeast)Non-thermal Processing Methods:Pulsed electric fields
High hydrostatic pressure
Gamma irradiation
• 11
• 14
• 7
Microbial cell ruptured due to uneven distribution of electrical charge across cell
Microorganisms ruptured under high pressure
Inability of microorganisms to reproduce
New thermal processing methods:Light pulsesOhmic heatingMicrowavingSous-vide technology
12 Optimized heating regime reduces levels of undesired microorganisms while minimizing thermally induced quality losses (e.g. impaired flavour)
Combined methods:Slight thermal treatment (blanching) Slight aw reduction
pH control
9 Reduction of initial microbial population and enzymatic activity; antimicrobial effect and control of deteriorative reactions; antimicrobial
Preservatives effect and avoidance of colour and texture changes
Refrigeration 1 Reduction of all deteriorative reaction rates
(Adapted from Ohlsson (1994)
6.- DRAG & DROP. The table below shows a comparison of Three Fruit Preservation Systems in Reference to Some Process Characteristics of Final Products and Processes. Fill in the gaps with the information from the box:
Fruit Process/ Technology
aw Overall Quality
Shelf Stability
Preservatives Added
Processes and Preservation Operations
Blanching Packaging
Minimally Processed Refrigerated Fruits (MPRF)
0.97-0.99
Fresh-like
refrigeration required
Might include some (i.e., ascorbic acid)
Peeling, coring, slicing, dipping in preservative solutions, dehydration
May be used (though excluded in most descriptions)
Required (MAP / CAPa may be used)
Minimally Processed High Moisture Fruit Products (HMFP)
0.93-0.98
Fresh-like to slightly modified
Shelf-stable at room temperature
Sulfites; sorbic, citric, benzoic, an ascorbic acid
Peeling, coring, slicing, dipping in preservative solutions, dehydration
Generally applied
Required
Intermediate Moisture Fruits (IMF)
0.75-0.92
Slightly modified to modified
Usually shelf-stable at room temperature
Sulfites; sorbic, citric, benzoic, an ascorbic acid
Peeling, coring, slicing, dipping in
Generally required
Required
preservative solutions, dehydration
MAP / CAP a (modified atmosphere packaging / controlled atmosphere packaging)
7.- FOLLOW-UP: The combination of the operations of the activity 5 to preserve a minimally processed food, as seen in the activity 6, is called Hurdle Technology. Each preservation operation is a hurdle that the microorganisms must jump over. The objective of the hurdles is avoiding that the microorganisms reach the far side. Explain what happens in each of the following cases:
a)
b)
Heating Chilling aw
Preserv.
Heating Chilling aw
Preserv.