ISO 6949:1988 果物と野菜—制御された雰囲気の貯蔵方法の原理と技術 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting.

International Standard ISO 6949 was prepared by Technical Committee ISO/TC 34, Agricultural food products.

Annex A of this International Standard is for information only.

Introduction

The extension of the keeping period for fruits and vegetables, with minimum loss, to the long term is closely linked to the rate of the metabolic processes occurring in the products and the rate of development of pathogenic micro-organisms and physiological diseases.

The use of cold storage, with control of the relative humidity of the air in the store, results in the reduction of the respiration rate and of transpiration, as well as of the development of some diseases.

Better results may be obtained, however, by the storage of fruits and vegetables in controlled atmospheres, which is based on the maintenance of the temperature and of the relative humidity at optimal values, and also involves the regulation of the gas composition in the store.

Storage in controlled atmospheres, combining the effects of three basic factors (temperature, relative humidity and gas composition), leads generally to a reduction in metabolic activity and, in the case of climacteric products (such as apples, pears, bananas and tomatoes), possibly to a delay in the appearance of the onset of the climacteric period.

The low-oxygen atmosphere reduces ethylene production and the combination of the low oxygen and high carbon dioxide levels reduces the effects of ethylene. Consequently, there is a delay in ripening, the nutritive value and the appearance for sale are maintained and the keeping period of the product can be extended.

Further, as a result of the reduction in oxygen content and increase in carbon dioxide content, the development of pathogenic micro-organisms and the appearance of some physiological disorders may be retarded.

The products stored in controlled atmospheres shall be of varieties and quality different from those of products stored under normal conditions.

1 Scope

This International Standard specifies the principles and techniques of controlled atmosphere storage for fruits and vegetables.

It applies to various kinds of fruits and vegetables (notably apples, pears and bananas). The application of this method is specific to each product; in addition to maintaining the optimum limits of temperature and of relative humidity, the oxygen content should also be reduced from 21 % (V/V) (the normal level) ; this means that the partial pressure of this gas is also reduced.

However, oxygen contents below 1,5 % (V/V) are not recommended since, in the absence of sufficient oxygen, fermentation processes take place (intracellular respiration) and a brownish discoloration of the fruits and vegetables may appear.

At the same time, the atmosphere is enriched in carbon dioxide; however, too high a carbon dioxide content [for example exceeding 8 % (V/V) to 10 % (V/V)] can in most cases cause various physiological diseases (carbon dioxide injuries) resulting in a reduction in quality as well as quantitative losses.

Annex A

Bibliography