ISO 1134:1993

INTERNATIONAL ISO
STANDARD 1134
Second edition
1993-1 O-I 5
- Cold storage
Pears
Poires - En treposage r6frigM
Reference number
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. Esch 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 voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 1134 was prepared by Technical Committee
lSO/TC 34, AgriculturaI food products, Sub-Committee SC 14, Fresh fruits
and vegetables.
This second edition cancels and replaces the first edition
(ISO 1134:1980), which has been technically revised.
Annexes A and B of this International Standard are for information only.
0 ISO 1993
All rights reserved. No part of this publication may be reproduced or utilized in any form or
by any means, electronie or mechanical, including photocopying and microfilm, without per-
mission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l Zl 1 Geneve 20 l Switzerland
Printed in Switzerland
ii
Introduction
This International Standard provides guidance of a very general nature
only. Because of the variability of the fruit according to the time and place
of cultivation, local circumstances may make it necessary to specify other
conditions of harvesting or other physical conditions in the store.
This International Standard does not apply unreservedly, therefore, to all
varieties in all climates, and each specialist will decide on any modifi-
cations to be made.
Moreover, it does not take into account the role played by horticultural
factors, and wastage during storage is not dealt with. The importante of
these two subjects has not been forgotten, but the influential factors (i.e.
ecological or agrotechnical factors) are not very well known; moreover, the
origin of many of the most frequent physiological disorders of pears is still
uncertain, as are often the appropriate means of combating them. lt was
therefore considered difficult to prepare recommendations on these two
Points.
Nevertheless, it was considered useful to give, in annex B, a few rec-
ommendations which appear sufficiently well founded in the present state
of knowledge.
Subject to all possible restrictions arising from the fact that fruits are living
material and may vary considerably, the application of the guidance con-
tained in this International Standard should enable much wastage in cold
storage to be avoided and long-term storage to be achieved in most cases.
. . .
Ill
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INTERNATIONAL STANDARD ISO 1134:1993(E)
Pears - Cold storage
b) Firmness of the flesh: estimated by means of a
1 Scope
spring penetrometer.
This International Standard gives guidance on con-
c) The total soluble solids content of the fruit, which
ditions for the successful cold storage of varieties of
should be at least 10 % at harvest: determined by
pears (Pyrus communis Linnaeus) up to their use in
a refractometer.
the fresh state.
d) Ease of Separation.
2 Normative references e) Presence of starch in the flesh of the fruits:
checked by treating a Cross-section of the fruit
with an iodine/potassium iodide Solution.
The following Standards contain provisions which,
through reference in this text, constitute provisions
The values obtained from these criteria are not uni-
of this International Standard. At the time of publi-
versally valid; for a given variety they vary from one
cation, the editions indicated were valid. All Standards
region to another and it is for the grower to decide
are subject to revision, and Parties to agreements
on his own criteria for picking, on the basis of experi-
based on this International Standard are encouraged
ence.
to investigate the possibility of applying the most re-
cent editions of the Standards indicated below.
Determination of the Optimum harvest time is more
Members of IEC and ISO maintain registers of cur-
important for early varieties (for example, Coscia) than
rently valid International Standards.
for late varieties.
ISO 2169:1981, Fruits and vegetables - Physical
The fixing of the time of harvesting has greater im-
conditions in cold stores - Definitions and measure-
portance for controlled-atmosphere storage than for
ment.
storage in air.
AGRI/WP.l/EUR.STAN.l, Apples and pears?
3 Conditions for harvesting and storage 3.2 Characteristics for storage
Fruit put into store should be of quality “extra” and
II II
3.1 Harvesting
I , the characteristics of which are defined in
AGRI/WP.l/EUR.STAN.l.
The practical criteria of ripeness most frequently used
for defining the best time for harvesting2) are the fol- Fruit put into cold store should be Sound, free from
lowing. bruises or physiological disorders, and free from any
visible sign of fungal or bacterial attack. lt should be
clean and free from any trace of water in the liquid
a) Basic colour of the outer skin:3) judged with the aid
state.
of a Standard table.
1) Revised European Standard, recommended by the Working Party on Standardization of Perishable Produce and Quality
Development of the Economic Commission for Europe.
2) The number of days after flowering is also used sometimes as a criterion for harvesting.
3) The basic colour should be distinguished from the red anthocyanin Pigmentation, the intensity and extent of which vary
according to the variety and, to some extent, with exposure to sunlight.

An accidental rise in storage temperature tan initiate
3.3 Putting into store
ripening, which continues when the fruit is again ex-
posed to the cold.
The fruit should be put into the cold store as soon as
possible after harvesting, the temperature being low-
Table 1 gives the storage temperature and duration
ered to a value suitable for the variety.
recommended for a number of varieties.
Rapid removal of field heat and precooling of har-
vested pears are essential for long storage.
4.2 Relative humidity
Pears may generally be stored at a relative humidity
3.4 Method of storage
of between 90 % and 95 %.
The fruit should be handled with care. The packages
4.3 Air circulation
should allow free circulation of air. Storage densities
of about 250 kg per cubic metre of usable space are
An air circulation ratio of 20 to 30 (see ISO 2169) or
recommended for a Stack of pallets.
Ventilation of 80 m3/h to 100 m3/h per tonne of fruit
The use of box pallets provides an increase of 10 % is recommended.
to 20 % in storage density.
4.4 Storage life
4 Optimum storage conditions
Table 1 gives the expected storage life under the
conditions mentioned above, for a number of var-
ieties. Storage should not be prolonged beyond limits
4.1 Temperature
compatible with the maintenance of good quality.
The pears should be kept at as low a temperature as
Samples of fruit should be taken in such a way as to
possible, subject only to avoiding the risk of freezing.
detect the appearance of any wastage.
In general, the best results are obtained at - 1 “C to
+ 0,5 “C.
4.5 Operations at the end of storage
A differente of 1 “C in storage temperature has a
The recommended ripening temperature for pears af-
profound effect on the time for which the pears tan
ter storage is 15 “C to 18 “C.
be kept. lt has been shown that, during cold storage,
the freezing-Point of the fruit falls slightly; it is on this
The ripening may be accelerated by ethylene treat-
account that, for Williams’ Bon Chretien pears, it has
ment. The gas is generally used at concentrations of
been possible to recommend a method of storage
1 % to 2 %, the treatment being carried out at a
based on progressive lowering of the temperature
temperature of + 18 “C and at approximately 90 %
(0 “C; - 0,3 “C; - 0,8 “C; - 1,5 “C). This procedure has
relative humidity.
enabled the storage life to be appreciably prolonged,
but it is difficult to carry out since it is not possible to
Table 1 gives the varieties which should undergo a
maintain a large bulk of fruit at a sufficiently uniform
complementary ripening after cold storage.
temperature in a cold store.
The course of development of the fruit during storage
5 Adjuncts and other keeping processes
depends on the choice of storage temperature. When
the temperature of the cold store is low (0 “C to
5.1 Controlled-atmosphere storage
- 1 “C) the Change in ripening characteristics of the
pears is very slow during cold storage and it is
The following
gas mixtures are most frequently rec-
necessary to submit them to a complementary
ommended:
ripening process at a higher temperature when they
are removed from the cold store. On the other hand, carbon dioxide l,o % to 3,0 %
from a certain temperature (+3 “C for Doyenne du Oxygen
2,0 % to 5,0 %
Comice pears, +4 “C for Passe Crassane), ripening is
These compositions are given only as a guide, and it
slow but tan be completed in storage.
is for the experts in each country to give any necess-
Some varieties ripen completely at higher tempera- ary advice on other kinds of compositions according
tures only if the storage period at low temperature to the particular requirements of each variety, as re-
has not been too long (for example, Comtesse de gards the content of carbon dioxide or of Oxygen in
Paris, Doyenne du Comice, Kaiser, Abbe Fetel, Louise the atmosphere or on account of particular local con-
Bonne d’Avranches and Williams’ Bon Chretien). ditions. Annex A gives an example of this.

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