ISO 22284-2020 pdf free.Leather — Raw skins — Guidelines forpreservation of goat and sheep skins.
1.scope:This document provides guidelines for various preservation methods for raw goat and sheep skins.Thepreservation methods are needed to suppress microbiological activity and to maintain the quality ofthe 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.
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 mediaand can grow even in the presence of high salt concentrations. During bacterial growth, they producepink, red orviolet pigments on salted skins, called red-heat. Sea or lake salt tends to be more susceptibleto contamination risk and development of red-heat.Hence, using rock salt is advantageous as it is freefrom chemical impurities.
Salt used in preservation processes should preferably contain 98 % sodium chloride (NaCl) of total dryweight and should not contain clumped particles. The impurities should not exceed the following limitsotherwise 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 canimmediately fall off the skin while handling.Particle size also affects speed of dissolution; therefore, toensure 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 thefresh weight.
4.3Auxiliary chemicals and preservation mixtures
Improvement in preservation could be achieved by the use of additional substances along withcommon salt.
The addition of sodium carbonate (Na,CO3) to the salt mixture prevents the formation of iron stainson skins, which can form due to existing impurities in salt. lf iron impurities exceed 0,01 % of the totalmass, iron stains occur in limed pelt, resulting in inferior quality.
Restricted pesticides or other toxic substances, such as pentachlorophenol (PCP), should not be used inpreservation mixtures.ISO 22284 pdf download.