PRESERVATION TECHNOLOGIES FOR FRESH FRUITS AND VEGETABLES:

COLD STORAGE, MODIFIED ATMOSPHERE PACKAGING AND

CONTROL ATMOSPHERE STORAGE

1ST WORKSHOP

January, 2002

Istanbul, Turkey

Financial support by the Commission of the European Union under MEDA programme is acknowledged (Thematic Network ICA3-C5-2000-30004)

Profª. Mª TERESA SANCHEZ

SPANISH FRUITS AND VEGETABLES:

PRODUCTION, IMPORTATIONS and EXPORTATIONS

FOOD CONSUMPTION

FOOD CONSUMPTION IN THE E.U.

MEDITERRANEAN COUNTRIES

PERISHABILITY AND PRODUCE LOSES

Have accurate control of temperature.

Reduce microbial loading.

Control and/or modify the packaging atmosphere. Deter enzymatic browning.

Maintain all of the above while offering a consistent, predictable quality level for all deliveries.

THE EMPHASIS OF ANY FRUIT AND

VEGETABLE PROGRAM IS TO:

COLD STORAGE OF FRUITS AND VEGETABLESCOLD STORAGE OF FRUITS AND VEGETABLES

COLD CHAIN

REFRIGERATED TRANSPORT

COOLING PROCESS

1. Reducing respiration and degradation by enzymes.

2. Reducing water loss and wilting.

3. Slowing the growth of decay organisms.

4. Reducing the production of ethylene, the natural ripening agent.

5. Providing time for proper handling and processing.

The most effective way to maintain quality and safety of fresh fruits and vegetables and their products is to maintain the COLD CHAIN, including the optimum range of relative humidity, throughout the postharvest life of the commodity.

MAXIMIZE THE SELF-LIFEMAXIMIZE THE SELF-LIFE MINIMIZE SHRINKAGEMINIMIZE SHRINKAGE

REFRIGERATED TRANSPORT

TEMPERATURE

CONTROLLED TRANSPORT

PROBLEMATICS OF FOOD PRESERVATION BY

REFRIGERATION

PROBLEMATICS OF FOOD PRESERVATION BY

REFRIGERATION

Requires continuous expense.

The cold chain (production, transport, store, consumption) should not be broken. Problems of interruption of cooling machine power and/or shortage of cooling agent (ice, eutectic mixtures).

Reduce enzymatic activity but do not kill, implies T<6 ºC for a few days but T<-18 ºC for a few months.

Cooling increases relative humidity and increases surface fungi.

Packed enclosure prevents it, but it asphyxiates vegetables. (Ambient humidity not relevant for frozen food.)

In mixed spaces some food give odours (potatoes) and others take (dairy). Some stores require ventilation for fresh air or air treatment for controlled atmosphere.

CONTROLLED ATMOSPHERE STORAGE OF SELECTED

FRUITS AND VEGETABLES

CO2 and O2 concentration

Relative HumidityTemperature

CONTROLLED ATMOSPHERE STORAGE

• Presence and quantity of:• CO2

• O2

• Ethylene• Products in optimum conditions:

• Type• Variety• Origin• Climatic background

• PRODUCTS:• Life can be extended by 30%• Losses and diseases are reduced by 30-80 %

Maximum concentration of CO2 and minimum concentration of O2 in AC storage

Kader, 1980

CA MANIPULATIONS

• Initial low oxygen stress treatment (ILOS).

• High CO2 shock treatments.

• A range of O2/CO2 concentrations.

• CA combined with other treatments as a possible replacement for SO2.

Lower values of O2 and CO2

Better gas-tight insulation techniques

Computer control systems

MODIFIED ATMOSPHERE PACKAGING OF SELECTED FRUITS AND VEGETABLES

PUTTING THE PRODUCT TO SLEEP

Produce generate their own atmosphere in plastic bags

• The rate of respiration of the commodity

• The properties of the film

• The storage temperature

Depending on:

Optimum CO2 and O2 concentrationin MAP

Broccoli 5:2; asparagus 10:10; lettuce 2:2; peaches 6:1.5; pears 2:2; carrots 0:21; blueberries 6:1.5

Optimum gas levels can vary according to:

•Cultivar or genotype•Production area•Harvest maturity•Other factors

The potential positive and negative effects MAP has on the Food Industry

Davies et al., 1995

MODIFIED ATMOSPHERE

• Produced naturally by respiration

PASSIVE M.A.The permeability characteristics of the film determine the equilibrium gas concentration achieved in the package.

• Produced by the application of gas flushing techniques

EQUILIBRIUM M.A.The actual equilibrium MA attained within a package will also depend on factors such as the prepared form of the vegetable studied, the rate of respiration at storage temperature, the pack volume and fill-weight, and the surface areas for gas exchange.

GENERAL EFFECTS OF MAP ON MICRO-ORGANISMS

Not well studied.

Gram negative bacteria (Pseudomonas) more sensitive to CO2 than Gram positive.

CO2 at sufficient concentration can inhibit the growth of spoilage moulds.

FACTORS TO CONTROL INMAP

• FOOD HYGIENE

• TEMPERATURE CONTROL

• STOCK ROTATION

• QUALITY ASSURANCE TESTS

• MICROBIOLOGICAL TESTING

• SEAL INTEGRITY

• GAS ANALYSIS

• TEMPERATURE MONITORING

FUTURE OF MAP

1 OPTIMISING MAP OF A VARIETY OF

FRESH PRODUCTS UNDER VARIOUS

STORAGE CONDITIONS.

2 TESTING MAP FILMS FOR CLIENTS.

3 EVALUATING EDIBLE COATINGS.

FOCUS AREAS OF FOCUS AREAS OF MAP RESEARCH:MAP RESEARCH:

ENVIRONMENTAL IMPACT OF PRESERVATION TECHNIQUES OF

FRUITS AND VEGETABLES

• CFC’s, the predominant refrigerants used in reefer containers.

• Proposed restrictions on HFC’s become a reality, refrigerated transportation will face serious challenges in finding acceptable substitutes.

QUALITY AND CONSUMER ACCEPTANCE

• High quality fruits and vegetables are one of today's wonders with regard to Spanish food supply.

• Unfortunately, many Spanish fruit and vegetable growers believe that once a high quality product is produced, their problems are over. In reality, their troubles could be just beginning. It has been estimated that more than 40 % of perishable commodities are lost after production.

• Price received for produce is determined by quality at the marketplace.

Direct contact between the seller and the consumer results in the consumer being able to select the particular items and enabling the seller to react quickly in response to consumer demands. This ensures a high level of consumer satisfaction.

Variables consumers perceive as a reflection of produced quality:Variables consumers perceive as a reflection of produced quality:

Producers who are able to produce and package their produce in such a way to enhance these variables are the most successful in the market place.

• Texture: Crispness and freshness.

• Flavor and taste.

• Nutritive value.

• Price.

• (1) The quality inspection procedures that must be carried out (Commission

Regulation 2251/92 of 29 July 1992),

• (2) What quality they must have (Common Quality Standards' that have been promulgated throughout the years), and

• (3) The maximum limits of pesticide residues admitted and how they should be controlled (Council Directive 76/895/EEC, 90/642/EEC and 93/58/EEC).

• Within the Regulation applied to foodstuffs, fruit and vegetables must fulfill the provisions on labels (Council Directive 79/112/EEC and the one that regulates the quantity of products in the packages (Council Directive 76/211/EEC).

How to assure the quality of a product? How to make commerce easier?

January, 2002

Istanbul, Turkey

Financial support by the Commission of the European Union under MEDA programme is acknowledged (Thematic Network ICA3-C5-2000-30004)

Profª Mª TERESA SANCHEZ

THANK YOU VERY MUCH

PRESERVATION TECHNOLOGIES FOR FRESH FRUITS AND VEGETABLES: COLD STORAGE, MODIFIED

ATMOSPHERE PACKAGING AND CONTROL ATMOSPHERE STORAGE

1ST WORKSHOP