How to use food bleach

Introduction: Food bleach is mainly used in food The following safety net introduces the use of food bleach According to the action mechanism, bleaching agents can be divided into two categories: reducing bleaching agents and oxidizing bleaching agents The reductive bleaching agents used in practice are mainly sulfite and its salts, such as sodium sulfite, sodium hyposulfite (insurance powder), potassium pyrosulfite and sodium, sodium bisulfite and sulfur fumigation Oxidation bleaching agents mainly include hydrogen peroxide, potassium permanganate, chlorine dioxide, acetone peroxide, benzoyl peroxide, etc Here is how to use bleach 1 Sodium sulfite has anhydrous substance and heptahydrate The molecular formula of anhydrous sodium sulfite is Na2SO3, molecular weight: 125.06, and the molecular formula of sodium sulfite heptahydrate is Na2SO3 · 7H2O Molecular weight: 252.5 (1) The character of anhydrous sodium sulfite is colorless to white crystal or crystal powder, odorless, the relative density is 2.633 It is soluble in water: 13.9% (0 ℃), 28.3% (80 ℃); slightly soluble in ethanol, soluble in glycerin, and its aqueous solution is alkaline The pH value of 1% aqueous solution is 8.4-9.4, with strong reducibility It is slowly oxidized into sodium sulfate (mirabilite) in the air and reacts with acid to produce sulfur dioxide Sodium sulfite heptahydrate is colorless crystal, odorless or almost odorless, with a relative density of 1.561, which is easily soluble in water: 32.8% (0 ℃), 16.9% (48 ℃); glycerin 30% (normal temperature) is heated to 150 ℃ and loses 7 molecules of crystal water to become anhydrous sodium sulfite (2) Performance sodium sulfite is a strong reducing agent, which can produce reductive sulfite Sulfite and coloring matter can reduce it, showing strong bleaching effect Sodium sulfite has a strong blocking and damaging effect on the activity of oxidase, so it has a good effect on preventing browning of plant food (3) The oral LD50 was 0.6-0.7g/kg (calculated by SO2) LD50 0.175g/kg (calculated by SO2) was intravenously injected into mice (4) In the preparation method, sulfur dioxide gas is introduced into the carbonic acid solution at 40 ℃, then sodium hydroxide solution is added after saturation, crystal sodium sulfite is obtained through crystallization, and then sodium sulfite is obtained by heating and dehydration (5) According to the standard of food additives in China's food hygiene regulations, the application scope and maximum use amount of sodium sulfite are as follows: dried gourd, 5g / kg; dried fruit (except raisin), 2G / kg; gelatin, 0.5g/kg; liqueur (excluding fruit juices and concentrated juice with alcohol content of more than 1% capacity), miscellaneous wine, 0.35g/kg; syrup, sugar, preserved cherry, 0.3g/kg; Natural fruit juice (for products diluted more than 5 times), 0.15g/kg sugar bean, 0.1g/kg; shrimp, 0.1g/kg; other food, 0.03g/kg; sesame milk, bean vegetables and raw edible blood are not allowed Sodium sulfite is mainly used as bleaching agent, but it can also be used as preservative and antioxidant It is more effective in inhibiting mould than yeast When it is used, it can be turned into 0.2% - 2% aqueous solution, which can be used to dip or spray on the fruit The fruit treated in this way can be stored to achieve the purpose of antioxidant and maintaining fragrance 2 Sodium hydrosulfite, also known as sodium hydrosulfite and sodium hyposulfite, is also known as insurance powder, with molecular formula of Na2S2O4 and molecular weight of 174.11 (1) Properties white crystalline powder, sometimes tinged yellow or gray, sulfur dioxide odor It is very unstable, has strong reducibility, is easy to oxidize and decompose, precipitates sulfur, is easy to dissolve in water, almost insoluble in ethanol Long time in the air will lose the ability to bleach, and may burn Decomposition occurs when heated to above 75-85 ℃, and explosion occurs when heated to 190 ℃ The relative density is about 1.3, which is soluble in water and insoluble in ethanol There are also dihydrate The dihydrate is not stable If heated slowly in alkaline medium, it can remove water and turn into anhydrous substance (2) The performance is compared with that of sodium sulfite, but the reduction capacity is stronger (3) The toxicity is the same as that of sodium sulfite (4) method Zinc powder reacts with sulfur dioxide to form zinc bisulfite, then sodium carbonate or sodium hydroxide is added to form sodium hyposulfite, then sodium chloride is added to precipitate the crystal of sodium hyposulfite, and finally dehydrate and dry it with ethanol (5) Use reference sodium sulfite The hygienic standard for the use of food additives in China (GB2760-1996) stipulates that the maximum use of sodium hyposulfite is 0.4g/kg for sugar, bamboo shoot, ice sugar, dried fruit, dried vegetable, vermicelli, candy, preserves, glucose, liquid glucose, caramel, biscuit and mushroom cans The residual amount shall be calculated by sulfur dioxide, and the content of bamboo shoots, mushrooms and canned mushrooms shall not exceed 0.05g/kg; the content of sugar, vermicelli and other varieties shall not exceed 0.1g/kg; the content of liquid glucose shall not exceed 0.2g/kg; the content of preserves shall not exceed 0.05g/kg 3 The alias of sodium pyrosulfite: sodium sulfite, molecular formula: Na2S2O5, molecular weight: 190.13 (1) The sodium pyrosulfite is a white crystal or powder with the odor of sulfur dioxide It is easy to dissolve in water and glycerin, slightly soluble in ethanol Its solubility in water is 30% (normal temperature) 50% (100 ℃), and the pH of 1% aqueous solution is 4.0-5.5 It can emit sulfur dioxide in the air and decompose It has strong reducibility (2) Toxicity ADI 0-0.75mg/kg (SO2 meter; including total ADI value of sulfur dioxide and sulfite) (3) the hygienic standard for the use of food additives in China (GB2760-1996), and the standard for the use of sodium pyrosulfite: the maximum use of sugar, ice sugar, candy, preserves, glucose, liquid glucose, Caramel, biscuits, bamboo shoots, vermicelli, mushrooms and mushroom cans is 0.45g/kg The residual amount is calculated by sulfur dioxide, and the canned bamboo shoots, mushrooms and mushrooms shall not exceed 0.05g/kg; biscuits, sugar, vermicelli and other varieties shall not exceed 0.1g/kg; liquid glucose shall not exceed 0.2g/kg; preserves shall not exceed 0.05g/kg Pyrosulfites are unstable, but they have a small odor and low price They are often used for bleaching fruits and vegetables Sodium pyrosulfite changes into sodium bisulfite when it meets water: Na2S2O5 + H2O → 2nahso3, so they are common Sodium pyrosulfite is stable in solid state and is commonly used 4 Sodium bisulfite is also known as sodium bisulfite The molecular weight of NaHSO3 is 104.1 (1) It is white massive crystal or powder with strong smell of sulfur dioxide and density of 1.48g/cm3 When exposed to the air, it is easy to gasify into sodium bisulfate, which is soluble in water and slightly soluble in alcohol The aqueous solution is acid The pH value of 1% aqueous solution is 4.0-5 The saturated aqueous solution of sodium bisulfite contains 41.4% NaHSO3 at 50 ℃ and 51.4% NaHSO3 at 97 ℃ Sodium bisulfite has strong reducibility and has destructive effect on vitamin B, so it can not be used in grain, meat and dairy products (2) Sodium bisulfite is usually produced by sodium carbonate absorption method The basic process of production is as follows: sodium bisulfite is obtained by absorption of tail gas of sulfuric acid production or sulfur dioxide generated by sulfur combustion with sodium carbonate solution The reaction formula is as follows: Na2CO3 + 2so2 + H2O → 2nahso3 + CO2 (3) Application As bleaching agent, preservative and antioxidant, sodium bisulfite is used in brewing, beverage and dry fruit preservation and processing In addition, sodium bisulfite is also used to produce saccharin, perfume, hydroxylamine hydrochloride, etc 5 sulfur / brimstone (1) properties Sulfur has several allotropes, generally two kinds of stable crystals, two kinds of non crystals, two kinds of liquids, insoluble in water, slightly soluble in alcohol and ether, slowly soluble in benzene, carbon tetrachloride and carbon disulfide The sulfur used for fumigating food is yellow, slightly sandy powder or block, with special sulfur smell, insoluble in water and alcohol, melting point 115 ℃ ~ 160 ℃, black, thick liquid, flammable The ignition point in the air is above 261 ℃, which produces blue flame and has the special odor of sulfur dioxide (2) The performance is the same as that of sodium sulfite, which has the function of antisepsis and bleaching This product is used for fumigation, producing sulfur dioxide gas when burning, antisepsis and bleaching (3) The process is natural or symbiotic with iron ore (4) Use standard: only limited to fumigating candied fruits, dried fruits, dried vermicelli and sugar, the residue is the same as sodium sulfite 2 cases: take 10-20g sulfur per cubic meter of space, burn and fumigate for 10-30 minutes, suitable for dried fruits and other things Sulfur dioxide is also known as anhydrous sulphite Molecular formula: SO2, molecular weight 64.07 (1) It is colorless gas with strong asphyxiating odor producing under normal temperature; melting point - 76.1 ℃; boiling point - 10 ℃; When the temperature is below - 10 ℃, it becomes colorless liquid, the specific gravity of liquid is 1.46, the specific gravity of gas is 2.263, it is easy to dissolve in water and ethanol, the solubility of water is 22.8% (0 ℃), and 5% (50 ℃) after sulfur dioxide dissolves in water, part of sulfur dioxide will hydrate with water to form sulphurous acid, which is unstable When heated water rapidly decomposes to release sulfur dioxide, it is easy to decompose under normal temperature, if it is not sealed, and it will gradually oxidize into sulfuric acid in air The content of sulfur dioxide is easy to change The 6% sulfur dioxide solution on the market is also called sulphuric acid anhydride solution (2) Performance as reducing agent, mostly as food preservative and bleaching agent, the same as sodium sulfite (3) When using sulfur dioxide fumigation, the fumigation room should have good ventilation equipment The scope of application includes dried fruits, dried vegetables, vermicelli, preserves, wine, fruit wine, etc the sulfur dioxide residue shall not exceed 0.05g/kg The concentration of sulfur dioxide in the fumigation room is generally 1-2%, and the maximum is 3% The quality of sulfur shall be excellent, and the arsenic content shall be less than 0.003% Sulfur is inflammable, attention shall be paid to fire prevention, and liquid sulfur dioxide shall be stored in pressure resistant steel cylinder Potassium metabisulfite (1) is a white crystal or crystalline powder with sulfur dioxide odor, which is easily soluble in water and hard to dissolve in ethanol The aqueous solution reacts with acid and sulfur dioxide escapes in contact with acid In the air, especially in the humid air, it can be oxidized to sulfate Grinding can lead to combustion (2) Its reducibility is stronger than that of sodium sulfite, and the aqueous solution is acidic, so it is easy to use (3) application The hygienic standard for the use of food additives in China and the standard for the use of potassium pyrosulfite are 0.6g/kg for sugar, ice sugar, candy, preserves, glucose, caramel, biscuits, cans, etc the residue of sulfur dioxide in bleached products is 0.05g/kg for biscuits, sugar, vermicelli, cans, etc and 0.05g/kg for other foods Over 0.1g/kg Many foods use bleach, so is it safe to bleach? In fact, if it is used according to the national regulations, it will not be dangerous Now the state has a food safety detector, which can quantitatively detect 50 parameters in the food on the spot So that we can eat more safe food, more food safety knowledge in the hundred safety net Editor in charge: he xianrob