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PRESERVATIVES | Classifications and Properties
PRESERVATIVES/Classifications and Properties
4773
PRESERVATIVES Contents Classifications and Properties Food Uses Analysis
Classifications and Properties B L Wedzicha, University of Leeds, Leeds, UK Copyright 2003, Elsevier Science Ltd. All Rights Reserved.
Background 0001
Preservatives are substances added to food to inhibit microbial spoilage. Chemical food spoilage by enzymatic and nonenzymatic mechanisms may be controlled by specific additives, e.g., antioxidants and antibrowning agents, which are described in the relevant articles. Substances such as common salt, sugar, vinegar, or spices, which are effective antimicrobial agents under appropriate conditions, are not regarded as food preservatives. Reactions of food preservatives, which are not part of the chemistry of food preservation but nevertheless affect food quality, will also be considered. The chemical reactions that lead to cured meat color and flavor are reviewed elsewhere.
Need for Preservatives 0002
0003
The use of preservatives to extend the life of foods and improve their safety has been recognized for thousands of years. Traditional methods of preserving foods have relied on fumigation by sulfur dioxide, curing with brines containing nitrites and nitrates, and smoking, in which phenolic antimicrobial agents are added to the food. These processes not only ensure that stored food is of acceptable microbiological quality but also frequently provide it with unique organoleptic characteristics. Food preservatives ensure the safety and organoleptic quality of food when sold in the type of marketing environment now found in the developed countries. A particular problem associated with multiuse packs of food, e.g., beverages and spreads, is that an initially sterile, pasteurized or hygienically assembled, food becomes infected with bacteria, fungi, and yeasts, and begins to spoil. The instability might arise because the food has been formulated in such a way that it has little or no natural protection
against microorganisms. For example, a low-fat spread contains significantly larger water droplets than butter and can, therefore, support microbial growth more readily. A preservative is particularly useful in such a product. A relatively short increase in storage life can be of significant economic and practical advantage. This is well illustrated with advantages gained by extending the shelf-life of bread by a few days. Food preservatives are often used in conjunction with other methods of food preservation, e.g., some preservatives allow a milder thermal treatment to be applied for the preservation of food with consequent improvement in textural and nutritional properties.
0004
Structures of Food Preservatives Substances commonly used to preserve foods are listed in Table 1. These represent a wide range of molecular structures and tendency to form ions. The carboxylic acids sorbic, benzoic, formic, acetic, lactic,
Table 1 Substances recognized as suitable for use as food preservatives Sorbic acid and Naþ, Kþ, Ca2þ salts Benzoic acid and Naþ, Kþ, Ca2þ salts Ethyl, methyl, and propyl p-hydroxybenzoate and Naþ salts Sulfur dioxide, Naþ and Ca2þ sulfites and hydrogen sulfites (bisulfites), Naþ and Kþ disulfites (metabisulfites or pyrosulfites) Biphenyl Orthophenylphenol Thiabendazole Formic acid and Naþ, Ca2þ salts Naþ and Kþ nitrite and nitrate Acetic acid and Naþ and Kþ, Ca2þ salts Lactic acid Propionic acid and Naþ, Kþ, Ca2þ salts Hydrogen peroxide Nisin
E200–E203 E210–E213 E214–E219 E220–E227
E230 E231 E233 E236–E238 E249–E252 E260–E263 E270 E280–E283
Those that are approved for use within the EC have their E-number shown alongside. The presence of any substance in this list does not imply that its use is permitted throughout the world. Biphenyl, orthophenylphenol, and thiabendazole are used for surface treatment.
0005
tbl0001
4773
PRESERVATIVES Contents Classifications and Properties Food Uses Analysis
Classifications and Properties B L Wedzicha, University of Leeds, Leeds, UK Copyright 2003, Elsevier Science Ltd. All Rights Reserved.
Background 0001
Preservatives are substances added to food to inhibit microbial spoilage. Chemical food spoilage by enzymatic and nonenzymatic mechanisms may be controlled by specific additives, e.g., antioxidants and antibrowning agents, which are described in the relevant articles. Substances such as common salt, sugar, vinegar, or spices, which are effective antimicrobial agents under appropriate conditions, are not regarded as food preservatives. Reactions of food preservatives, which are not part of the chemistry of food preservation but nevertheless affect food quality, will also be considered. The chemical reactions that lead to cured meat color and flavor are reviewed elsewhere.
Need for Preservatives 0002
0003
The use of preservatives to extend the life of foods and improve their safety has been recognized for thousands of years. Traditional methods of preserving foods have relied on fumigation by sulfur dioxide, curing with brines containing nitrites and nitrates, and smoking, in which phenolic antimicrobial agents are added to the food. These processes not only ensure that stored food is of acceptable microbiological quality but also frequently provide it with unique organoleptic characteristics. Food preservatives ensure the safety and organoleptic quality of food when sold in the type of marketing environment now found in the developed countries. A particular problem associated with multiuse packs of food, e.g., beverages and spreads, is that an initially sterile, pasteurized or hygienically assembled, food becomes infected with bacteria, fungi, and yeasts, and begins to spoil. The instability might arise because the food has been formulated in such a way that it has little or no natural protection
against microorganisms. For example, a low-fat spread contains significantly larger water droplets than butter and can, therefore, support microbial growth more readily. A preservative is particularly useful in such a product. A relatively short increase in storage life can be of significant economic and practical advantage. This is well illustrated with advantages gained by extending the shelf-life of bread by a few days. Food preservatives are often used in conjunction with other methods of food preservation, e.g., some preservatives allow a milder thermal treatment to be applied for the preservation of food with consequent improvement in textural and nutritional properties.
0004
Structures of Food Preservatives Substances commonly used to preserve foods are listed in Table 1. These represent a wide range of molecular structures and tendency to form ions. The carboxylic acids sorbic, benzoic, formic, acetic, lactic,
Table 1 Substances recognized as suitable for use as food preservatives Sorbic acid and Naþ, Kþ, Ca2þ salts Benzoic acid and Naþ, Kþ, Ca2þ salts Ethyl, methyl, and propyl p-hydroxybenzoate and Naþ salts Sulfur dioxide, Naþ and Ca2þ sulfites and hydrogen sulfites (bisulfites), Naþ and Kþ disulfites (metabisulfites or pyrosulfites) Biphenyl Orthophenylphenol Thiabendazole Formic acid and Naþ, Ca2þ salts Naþ and Kþ nitrite and nitrate Acetic acid and Naþ and Kþ, Ca2þ salts Lactic acid Propionic acid and Naþ, Kþ, Ca2þ salts Hydrogen peroxide Nisin
E200–E203 E210–E213 E214–E219 E220–E227
E230 E231 E233 E236–E238 E249–E252 E260–E263 E270 E280–E283
Those that are approved for use within the EC have their E-number shown alongside. The presence of any substance in this list does not imply that its use is permitted throughout the world. Biphenyl, orthophenylphenol, and thiabendazole are used for surface treatment.
0005
tbl0001