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

peeling slicing

chopping blanching

freezing

dipping hurdles

husking coring

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.

c)

d)

e)

Chilling aw

Preserv.pHVitaminsNutrients

Chilling aw

Preserv.pH

Chilling aw

Preserv.pHVitaminsNutrients