ISO 22284:2020 pdf download

ISO 22284:2020 pdf download.Leather — Raw skins — Guidelines for preservation of goat and sheep skins
1 Scope
This document provides guidelines for various preservation methods for raw goat and sheep skins. The preservation methods are needed to suppress microbiological activity and to maintain the quality of the skins during storage.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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4 Characteristics of salt and auxiliary substances used in preservation processes
4.1 Characteristics of salt
For preservation by salting, clean salt should be used. Halophilic bacteria get acclimatised to salt media and can grow even in the presence of high salt concentrations. During bacterial growth, they produce pink, red or violet pigments on salted skins, called red-heat. Sea or lake salt tends to be more susceptible to contamination risk and development of red-heat. Hence, using rock salt is advantageous as it is free from chemical impurities. Salt used in preservation processes should preferably contain 98 % sodium chloride (NaCl) of total dry weight and should not contain clumped particles. The impurities should not exceed the following limits otherwise the salt may negatively affect the quality of the finished product: — Total calcium (Ca) and magnesium (Mg) compounds in salt: 1 %. — Total iron (Fe) compounds: 0,01 %. Particle size of salt is also important to achieve effective preservation. If salt particles are very fine, salt tends to form pasty patches with uneven coverage. If salt particles are very coarse, they can immediately fall off the skin while handling. Particle size also affects speed of dissolution; therefore, to ensure an appropriate dissolution, particle size of salt should be 2 mm to 3 mm.
4.2 Quantity of salt
To ensure proper dehydration of raw skins, the quantity of salt should not be less than 30 % of the fresh weight.
5.3 Wet salting
Wet salting is the most common method of curing skins around the world. Wet salting is carried out by treating skins with common salt. After skinning, skins are salted at slaughterhouses to prevent decay. Wet salting removes 55 % of the water from the skin mass. Skins are kept for 3 d to 6 d in piles to drain excess water content. The amount of salt used should not be less than 30 % of the total raw skin mass. Salt or salt mixture should be applied to both sides of skins and the salt particles should penetrate between the fibres on the skins. Properly salted skins should have a water content of lower than 48 % and the salt saturation should be at least 85 % in order that long-term preservation can be achieved under convenient conditions. In terms of quality, the water content of salted skins should be 40 % to 45 % and salt particulates should penetrate throughout the cross-section.