食品添加剂 防腐剂.ppt

Click to edit Master title style,*,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,(第二章 防腐剂),Chapter 2 Preservatives,Contents:,2.1,Definition,of preservatives,*,2.2,Mechanisms of preservatives,*,机理,2.3,Varieties of preservatives,*,种类,2.4,Classification of preservatives,*,分类,2.5,Introduction to the preservatives used often in food,2.5.1,Benzoic acid and its sodium salt,*,苯甲酸,2.5.2,Sorbic,acid and its potassium salt,*,山梨酸,2.5.3,Sodium and calcium propionate,*,丙酸,2.5.4,Parabens/p-hydroxybenzoates,*,(sum),对羟基苯甲酸酯,*,Nisin,*,乳酸链球菌素,*,fresh-keeping preservatives for fruits and vegetables,*,2.6,Attention to the application of food preservatives,*,2.7,Development tendency of food preservatives,*,(Questions for discussion),2.5.5,other preservatives,Examples of foods which easily undergo spoilage as the result of microbial action,meat products,cheese,bread,spices,Fruit juice,aquatic products,Methods for preserving foods,(1)Physical methods:,*Drying in the sun,*low-temperature storage(freezing/frozen storage),冷冻冷藏,*pickling/salting,sugaring,腌制,*soaking with wine,腌制、浸酒,*fermentation,发酵,Traditional,physical methods：,New Physical Methods:,*,Canning packaging,罐藏,*vacuum/gas packaging,真空、气体,*high hydrostatic pressure(sterilization),高压,*irradiation sterilization,辐照,*electron sterilization,电子辐照,(2)Chemical Methods,：,preservatives,1.,Definition,(,),Food preservatives may be defined as substances which can kill microorganisms or prevent the growth of microorganisms.,抑制或杀死微生物的物质,Or in simple words,preservatives are substances used in foods which have antimicrobial effects.,抗菌效果,Attention:,spices such as sugar,vinegar,and salt,which also have anti-microbial effect,are not included.,调味品如糖、醋、盐有抗菌效果，没有包括,Disinfectants used for sterilizing food containers are not included either.,用于容器的消毒剂也不包含在内,2.2 Mechanisms of preservatives,(1),Food spoilage caused by micro-organisms(three types),食品腐败三种形式,Food spoilage caused by the action of bacteria.,细菌的作用,Food spoilage caused by the action of molds,霉菌的作用,*alcohol fermentation,酒精,*acetic acid fermentation,醋酸,*lactic acid fermentation,乳酸,*,butylic,acid fermentation.,丁酸,Food fermentation:,发酵,(2),Mechanisms of food preservatives,(,),Destroy the structure or change the permeability of microbial cell membrane,破坏或改变微生物细胞膜的通透性,Interfere with microbial enzyme systems,干扰微生物酶系统,Other effects:cause the,denaturation,of microbial proteins,微生物蛋白失活,Example:mechanisms of,sorbic,acid,1)Inhibit,dehydrogenases,involved in fatty acid oxidation.,抑制脂肪氧化脱氢酶,Interfere with microbial enzymes:,2)Inhibit,sulfhydryl,enzymes.,抑制巯基酶,2.3 Varieties of preservatives,(1)Varieties,:,about 50 in USA,40 in Japan,and 32 in China.,(2),Preservatives in China:,(,),Food preservatives:,benzoic acid and sodium benzoate,苯甲酸（盐）,sorbic,acid and potassium,sorbate,山梨酸,propionic,acid,sodium and calcium propionate,丙酸,parabens,(ethyl and,propyl,),对羟基苯甲酸酯（乙酯，丙酯）,dehydroacetic,acid,and sodium,dehydroacetate,sodium,diacetate,脱氢醋酸（盐）,carbon dioxide CO,2,nisin,(,尼生素，乳酸链球菌素,),hydrogen peroxide H,2,O,2,natamycin,(,纳它霉素,）,capryl,monoglyceride,(,单辛酸甘油酯,),Fresh-keeping preservatives for fruits and vegetables,:,sec-,butylamine,（,仲丁胺,）,-phenyl phenol,（,邻苯基苯酚,）,thiabendazole,（,噻苯咪唑,）,ethoxyquin,（,乙氧基喹,）,cinnamaldehyde,（,桂醛,肉桂醛,）,chlorine dioxide,（ClO,2,）,glutaraldehyde,（,戊二醛,）,sodium,o-phenylphenolate,（,2-,苯基苯酚钠）,The following substances also have,antiomicrobial,effects:,nitr,ite,s:used as color fixatives,发色剂,short-chain organic acids:used as acids,短链有机酸,sulf,ite,s:used as bleaching agents,漂白,sucrose,ester,s,（,蔗糖酯,）,:,used as emulsifiers,.,乳化剂,glucono-,-lactone:used,as a coagulator,凝固剂,2.4.C,lassification of preservatives,(1)According to their components,they can be classified into-,chemical preservatives,:,化学,*,organic preservatives:most,有机防腐剂,Eg,:,benzoic acid and sodium benzoate,sorbic,acid and potassium,sorbate,.,苯甲酸，山梨酸（盐）,*inorganic preservatives:nitrite,sulfite,无机,biological preservatives,:,nisin,natamycin,.,生物防腐,，,乳酸链球菌素，纳塔霉素,food,perservatives,:most,防腐,fresh-keeping preservatives for fruits and vegetables,保鲜,(2)According to their application range,they can be classified into-,(3)According to their sources,they can be classified into-,来源,(4)According to their antimicrobial effect,they can be classified into-,natural preservatives,:,nisin,natamycin,synthetic preservatives,:most,bacterio,stat,ic,:,substances which can only prevent the growth of microbe,.,抑制,bacteri,cid,ic,:,substances which can kill microorganisms,.,杀菌剂,2.5.Introduction to the preservatives commonly used in foods,(,),2.5.1 Benzoic acid and sodium benzoate,.,苯甲酸和苯甲酸钠,source:,synthetic preservatives.,structures:,page 41,General properties:,water solubility,Water solubility,:,benzoic acid,:,slightly,soluble in water (0.34g/100ml at 25,).,sodium benzoate,:,highly,soluble in water(50g/100ml at 25,).,Antimicrobial activity,:,Effective against most molds,yeasts and bacteria.,The,undissociated,form of benzoic acid is the most effective antimicrobial agent.,没离解的苯甲酸抗菌效果最好,pH values of foods affect their antimicrobial effects.They are only effective in acidic conditions with the optimal pH of 2.5-4.0.,pH,影响抗菌效果，它们只在酸性段有效,For example,under optimal pHs,their MIC are as low as 0.05-0.1%for most microbes.,在最宜,pH,最多数微生物，,MIC,低至,0.05%-0.1%,Toxicology:,low toxicity,Oral LD,50,:2530mg/kg for benzoic acid;4070 mg/kg for sodium benzoate.,ADI,:0-5mg/kg for both,GRAS,Applications,Application standards:,Table 2-3.,E:0.2-2.0 g/kg,Examples:,1)0.1%is effective in soy sauce,vinegar,fruit juice and jams.,2)0.05%is effective in pickles with low salt and preserved fruits.,2.5.2,Sorbic,acid and potassium,sorbate,.,source,:,synthetic preservatives,sorbic,acid:slightly soluble (0.16g/100ml at 20,).,potassium,sorbate,:highly soluble(67.6/100m at 20,).,Structures,:,page 44.,General properties,:,Water solubility,Antimicrobial activity,(,),Effective against most molds,yeasts,and aerobic bacteria but almost ineffective against anaerobic and lactic bacteria.,对霉菌，酵母，好氧菌有效，对厌氧菌和乳酸菌无效,The,undissociated,form of,sorbic,acid is the most effective antimicrobial agent.,没有离解的山梨酸抗菌效果最好,pH value of foods affect their antimicrobial effects.They are only effective in acidic condition with optimal pH lower than 6.0.,pH,影响抗菌活性，,pH,小于,6,时效果最好,Eg,:,at pH3,its MIC for most microbes is 0.01%,but at pH6,MIC increases,to 0.2%.,例如，,pH3,是，,MIC,为,0.01%,，而,pH6,时，,MIC,为,0.2%,ADI:0-25mg/kg for both,Toxicology:,Sorbic,acid is considered one of the least harmful antimicrobials.,毒性最低的抗菌剂,Oral LD,50,:7360mg/kg for,sorbic,acid;4920 mg/kg for potassium,sorbate,.,GRAS,Applications,Application standards:,Table 2-6.,E:0.2-2.0 g/kg,Examples:,1)In jams stored at 32,when 0.05%,sorbic,acid was added,no spoilage was found in 12 days,but the control sample underwent spoilage in 3 days.,2),The shelf-life of beverage could extend to 1 month when 0.02%,sorbic,acid was added compared to the control with the shelf-life only being 3 days.,加入 山梨酸可以把饮料的货架期延长到一个月，而对照只有,3,天,3)At 4,and 15,the shelf-life of the chicken carcass immersed first in boiling water for 10s then in a solution containing 6%,sorbic,acid for 60s was 35 and 57 times as long as that of the control respectively.,鸡肉先放进沸水处理,10,秒钟，然后放入含,6%,的山梨酸溶液中,60,秒可以保货架期分别演唱,3-5,，到,5-7,倍。,2.5.3 Sodium and calcium propionates,丙酸钠和丙酸钙,source,:,synthetic preservatives,合成,Structures:,CH,3,CH,2,COONa and,(CH,3,CH,2,COO),2,Ca,General properties:,一般性质,water solubility,水溶性,sodium propionate,:,highly soluble (100g/100 ml at 15,),;,potassium propionate,:,highly soluble(39.9g/100ml at 20,).,Antimicrobial activity,Effective against molds,but little effective against bacteria and ineffective against yeasts.,对霉菌有效，但对细菌和酵母无效,The,undissociated,form of,propionic,acid is the most effective antimicrobial agent.,未离解的形式抗微生物效果最好,pH value of foods affect their antimicrobial effects.They are only effective in acidic condition with optimal pH lower than 5.5.,pH,有影响,小于,5.5,时才有效。,Eg,:For example,at pH5.0,MIC for calcium propionate is 0.01%,while at pH5.8,the MIC rises to 0.188%.,ADI:not specified.,Toxicology,:,Oral LD,50,:6300mg/kg for sodium salt,3340 mg/kg for calcium salt.,GRAS,Applications,应用,Application Standards:,标准,1)Sodium propionate is allowed in cake with a limit of 2.5g/kg.,丙酸钠,2)Calcium propionate is allowed in wet crude flour products with a limit of 0.25 g/kg and in bread,vinegar,soy sauce,cake and soy bean products with the maximum amount of 2.5 g/kg.,丙酸钙，面包，醋，酱油，蛋糕，豆制品,Examples:,1),The shelf-life of bread could be increased by 2-4 days when 0.25%calcium propionate was added in it.,加入,0.25%,的丙酸钙可以延长面包的货架期,2-4,天,2)The,mooncake,could be increased by 30-40 days in shelf-life with the addition of 0.25%calcium propionate.,加入,0.25%,的丙酸钙，月饼货架期可增加,30-40,天,Attention,:,In bakery products,when chemical bulking agents such as sodium bicarbonate are used,sodium propionate is preferred.,焙烤食品中使用碳酸氢钙时使用丙酸钠较好,(,2.5.4),Parabens/p-hydroxybenzoates,They are alkyl esters of,p-hydroxybenzoic,acid,.,对羟基苯甲酸的酯,Parabens,used as food preservatives include:,General,Structure:page 49.,methyl-,p-hydroxybenzoate,/,methylparaben,甲基,ethyl-,p-hydroxybenzoate,/,ethylparaben,(),乙基,propyl-p-hydroxybenzoate,/,propylparaben,(),丙基,isopropyl-,p-hydroxybenzoate,/,isopropylparaben,异丙基,butyl-,p-hydroxybenzoate,/,butylparaben,丁基,isobutyl-,p-hydroxybenzoate,/,isobutylparaben,异丁基,n-heptyl-p-hydroxybenzoate,/,hetylparaben,正庚基,solubility,:,slightly soluble in water,but highly soluble in ethanol,and related to the alkyl chain length.,General properties:,source:,synthetic preservatives,*but the water solubility of,parabens,is inversely related to the alkyl chain length.,水溶性则与烷基链的长度反相关,*The solubility of,parabens,in ethanol increases as the alkyl chain increases.,在乙醇中的溶解度随着烷基链的增长而增加,Antimicrobial activity,(,),They are more active against molds,yeasts than against bacteria.,对霉菌酵母比对细菌更有效,Against bacteria,they are more effective against gram-positive than gram-negative bacteria.Also,they are infective against,lactic bacteria,.,阴性菌，阳性菌，对乳酸菌无效。,The antimicrobial activity of,parabens,is directly proportional to the alkyl chain length.,与烷基链长度有关,The,undissociated,form of,parabens,is the most effective agent.,Parabens,are effective at both acidic and alkaline pH levels with the optimal pH value of 4-8 .,酸性碱性都有效，最佳,pH 4-8,?,ADI:0-10mg/kg.,Toxicology:,Low toxicity and the longer the alkyl chain,the lower the toxicity.,GRAS (for methyl and,propyl,parabens,),Oral LD,50,:5000mg/kg for ethyl-,paraben,6700 mg/kg for,propyl-paraben,.,Applications,应用,Application Standards:Table 2-9.,E:0.10-0.5 g/kg,Examples:,The mixture of methyl and,propyl,parabens,(3:1)at the level of 0.03-0.06%could be used to increase the shelf life of fruit cakes,and pie crusts.,Summarization of the above preservatives,(,),Preservatives,LD,50,(mg/kg),ADI,(,mg/kg),E,(g/kg),Benzoic acid,2530,0-5,0.2-2.0,Sodium benzoate,4070,Sorbic,acid,7360,0-25,0.2-2.0,Potassium,sorbate,4920,Toxicity and permitted maximum levels,Continuted,:,preservatives,LD,50,(mg/kg),ADI,(mg/kg),E,(g/kg),Sodium propionate,6300,Not specified,0.25-0.5,Calcium propionate,3340,Ethylparaben,5000,0-10,0.1-0.5,Propylparaben,6700,Antimicrobial activity,(,),Preservatives,bacteria,yeasts,molds,Optimal pH,Benzoic acid,+,+,+,2.5-4,Sorbic,acid,+,+,+,6,Propion-ic,acid,+,_,+,5.5,parabens,+,+,+,4-8,Application in main foods,Food item,PA,SA,BA,PB,Cheese,酪,+,+,(+),(+),Meat products,-,+,-,(+),Aquatic products,-,+,+,+,Vegetable products,-,+,+,(+),Fruit products,-,+,+,(+),Soft drink,-,+,+,(+),Grape wine,-,+,-,-,bread,+,+,-,-,Confection,糖果,-,+,(+),+,1.Why are,propionic,acid and its salts suitable antimicrobials for bread?,丙酸及其盐,Three reasons:,Firstly,propionic,aid and its salts are effective against molds,and still have antimicrobial activity in breads with relatively high pHs as the dissociating constant of,propionic,acid is low.,Questions for Discussion,Secondly,they are effective against bacillus which easily cause rope（,粘连）,in bread.,Thirdly,they do not have effects on yeasts,so they will not affect fermentation.,对酵母无害，不影响发酵,2.B,enzoic acid and its salt are not used as preservatives in most meat products,why?,Two reasons:,Firstly,the pH values of most meat products are not at the optimal pH range of benzoate activity.,Secondly,benzoic acid is not effective against,C.,botulinum,.,肉毒杆菌,3.Why can,sorbic,acid and potassium,sorbate,be used in most foods?,Two reasons:,Firstly,they are effective against most,microorganisms,.,Secondly,they are effective in wide pH range.Its optimal pH is below 6,but it still has,antiomicrobial,activity when pH is up to 6.,4.Though,parabens,have many advantages compared to other compounds,they are seldom used in most foods,why?,优点多，却少用，为什么？,Two reasons:,Firstly,low water,solubillity,.,Secondly,astringent taste,（,涩味）.,(5),Other preservatives,structure:,Nisin,is a peptide consisting of 34 amino acids produced by,lactococcus,lactis,with the molecular weight being 3500.,肽，氨基酸，分子量,1),Nisin,Properties:,Water solubility,pH-dependent,soluble in acidic pHs and decrease with pH rising,insoluble when pH,7,stability,pH-dependent,stable in acidic pHs and decrease as pH increases.,Antimi-crobial,activity,pH dependent,bacteria(+),yeasts(-),molds(-),optimal pH 2-5.,与,pH,有关,Safety,(mg/kg),LD,50,14700,ADI,825,E,0.2-0.5(g/kg),Applications,Application Standards:,Nisin,is permitted in canned foods,vegetable protein beverages with a limit of 0.2g/kg;is permitted in milk products,meat products with the maximum level of 0.5g/kg.,罐藏，植物蛋白饮料,Examples:,1)1-10mg/kg of,nisin,was suggested to milk products such as cheeses,pasteurized milk,and flavored milk.,奶酪，巴氏奶，风味奶,2)2-2.5 mg/kg of,nisin,was suggested to canned vegetable products such as canned pineapple,cherry,apple and tomato jam.,菠萝，樱桃，苹果，西红柿酱,3)150-200 mg/kg of,nisin,was suggested as an adjunct to nitrite in cured meats for the purpose of preventing the growth of,clostridia,（,与亚硝酸盐并用，腌肉，梭状菌）.,2),Fresh-keeping,preservaties,for fruits and vegetables,保鲜,Preservatives,used for surface treatment for integral fruits and vegetables during their storage.,They,are usually,alkaline substances,including,sec-,butylamine,-phenyl phenol,and,thiabendazole,etc.,Antimicrobial activity,preservatives,bacteria,yeasts,molds,sec-,butylamine,+,+,+,o-phenyl phenol,+,+,+,thiabendazole,Wide antimicrobial spectrum,effective against most fungi.,宽的抗菌谱，对大多数真菌有效,sec-,butylamine,:,oral LD,50,is 660 mg/kg.,-phenyl phenol,:oral LD,50,is 2430-3000mg/kg;ADI is 0-0.2 mg/kg.,toxicology:,thiabendazole,:oral LD,50,is 3600 mg/kg;ADI is 0-0.1mg/kg.,They should not be added into final foods but,used as preservatives for fruits and vegetables during their storage.Their maximum levels and residues should be restricted according to GB2760-1996.,不用于最终产品，用于果蔬储运，最大量按国家标准,Application,For example:,according to GB2760-1996,the maximum level of,thiabendazole,is 0.02g/kg,and its residue should be lower than 0.002g/kg.,残留量,They are,usually compounded to solutions to soak fruits or vegetables or be sprayed into the surface of the products.,浸或者喷,They can also