potato chip
First, the use of food additives in potato chips
The main ingredients of potato chips are potato flour, refined vegetable oil, starch, modified starch, corn flour, seasonings (white sugar, chicken powder, edible salt, sodium glutamate, corn starch, paprika, soy sauce powder, compound spices, sunset yellow, lemon yellow), edible salt, emulsifier, antioxidant.
In the ingredients, the main food additives used are mainly phosphate ester bis starch, acid treated starch, hydroxyphenyl di-starch phosphate, monostearate glyceride, calcium carbonate, citric acid, sodium D-isocorbate, terbutylhydroquinone, silicon dioxide, lemon yellow, caramel color and so on.
(a) Phosphate ester bisamyl
1, properties: white powder, gelatinization temperature is higher and wetness is low. ADI does not make special provisions (FAO/WHO, 1994). The paste viscosity of phosphate ester bis starch is highly stable against thermal, acid and shear effects.
2. Uses: Used as thickener and stabilizer. It can be used as a thickener for salad juice. Phosphate ester bisambar has high freezing stability and freeze-thaw stability, and is particularly suitable for applications in frozen foods. Frozen or freeze-thawed at low temperatures for a long time, the melting is repeated many times, and the food still maintains the original tissue structure and does not change. Acid modified starch is the main raw material for ice cream after being diester phosphate. The crosslinked starch dried by the drum increases the volume of the pastry, making the pastry crisp, soft and shelf-resistant.
3, dosage: China's "Food Additives Use Hygiene Standards" (GB2760-1996) stipulates: for lunch meat, the maximum use of phosphate starch is 0.5g/kg; for jam 1.0g/kg. FAO/WHO regulations: 5 g/kg for mayonnaise, canned palm oil (edible) (used alone or in combination with acidic, alkali-treated or decolored starch, mono-starch phosphate, bis starch phosphate, bisamma acetylate, 10 g/kg canned mushrooms, asparagus, green beans, carrots containing cream or other fats and oils, 20 g/kg canned sardines or sardine fish products (for fillers only); milk substitute powder 25 g/ kg (for hydrolyzed amino acid-based products used alone or in combination with phosphorylated bisammonose); 60 g/kg canned mackerel and bamboo shootfish (for fillers only); canned baby food (soybean-based products) 5 g/kg; broth and clear broth, quick-frozen fish strips and fish chunks (only those wrapped in bread flour and bread mop) 25 g/kg (used alone or in combination with other starches in products based on amino acids or hydrolyzed proteins).
(2) Acid-treated starch
1, nature: white or off-white powder, odorless, tasteless, more soluble in cold water, about 75 ° C began to gelatinize. With the same concentration of this product, the viscosity of the starch paste is lower than that of the same kind of raw starch, and cooling at a certain concentration can form a gel.
2. Uses: Can be used as thickener, stabilizer, emulsifier.
3, dosage: the dosage is FAO/WHO (1984): mushrooms, asparagus, green beans, knife beans, white knife beans, sweet corn, canned carrots and heat-treated yogurt after fermentation, the maximum use of 10g/kg; canned sardines 20g/kg; mackerel, canned fish 60g/kg; meat soup, soup, GMP; ice 30g/kg (final product). Dosage can be used for seasonings (sauce powder), soups, candies (including chocolate and its products), the maximum use of 25g/kg; ice cream, popsicles, 5g/kg; jelly, jelly powder, non-carbonated beverages, flour, instant noodles, jam, soy sauce powder, cheese products, according to the production needs of the appropriate amount of use.
(3) Monostearate glyceride
1. Properties: Glyceryl monostearate is prepared by esterification reaction with glycerol containing C16-C18 long-chain fatty acids. It is a non-ionic surfactant. It has both hydrophilic and lipophilic genes, and has a variety of functions such as wetting, emulsification, and foaming. The first grade of this product is a milky white wax-like solid, soluble in methanol, ethanol, chloroform, acetone and ether and other solutions. The product is an emulsifier.
2, use: in the application of food additives, bread, biscuits, pastries and other use of the largest amount, followed by cream, butter, ice cream. It is used as an excipient in pharmaceutical products for the preparation of neutral ointments; in daily chemicals, it is used for the preparation of alabaster, ice cream, and chrysalis oil. It is also used as a solvent for oils and waxes, hygroscopic powder protectors and opaque opaque opacifiers. Glycerol fatty acid esters produced by the reaction of glycerol and fatty acids have monoesters, disastrous, triesterides, and triesterides are oils and fats, and have no emulsifying ability at all. Generally, a mixture of monoesters and diesters can be used, and can also be distilled and refined to obtain a monoester content of about 90% of the product. The fatty acids used can be stearic acid, palmitic acid, myristic acid, oleic acid, linoleic acid and the like. However, in most cases, a mixture of fatty acids with stearic acid as the main component is used.
3. Dosage: China's "Sanitary Standards for the Use of Food Additives" (GB2760-1996) stipulates that it can be used in various types of food according to production needs. Used in candy and chocolate, it can prevent the separation of milk sugar and toffee from oil and fat; prevent the separation of chocolate sugar crystals and oil and water, increase the sense of delicacy; improve the moisture resistance of candy, reduce deformation, prevent sticky teeth, and improve taste. The dosage is 0.2%-0.5%; for ice cream, the tissue can be mixed evenly, the tissue is delicate, smooth, and puffed moderately, and the conformability is improved; used for margarine, which can prevent the separation of oil and water, layering and other phenomena, and improve the quality of the product; for beverages, added to the lipid protein drink, can improve the stability, prevent the oil from floating, protein sinking; used for cakes or bread, compatible with other emulsifiers, as a foaming agent for pastries, and proteins form a complex, thereby producing a moderate bubble film, The prepared snacks are enlarged, soft, elastic and prolong the shelf life; for biscuits, added to the dough can make the grease evenly dispersed in an emulsified state, effectively preventing grease from oozing out and improving the crispness of biscuits. When using, the monostearate glyceride is dissolved with a small amount of hot water before adding.
(4) Calcium carbonate
1. Properties: white microcrystalline fine powder. Odorless and tasteless. The relative density is 2.5 to 2.7. Easy to absorb odor. Stable in the air. Decomposes at a strong heat of 825~896.6°C (produces CO2 and becomes calcium oxide). Almost insoluble in water and ethanol. The presence of ammonium salts or carbon dioxide increases their solubility in water, while hydroxide alkali reduces solubility. Slightly hygroscopic. Soluble in dilute acids (acetic acid, dilute hydrochloric acid, dilute nitric acid) and produces CO2. Insoluble in dilute sulfuric acid. According to the size of the powder, it can be divided into heavy calcium carbonate (30~ 50 μm), light calcium acidate (5 μm), colloidal calcium carbonate (0.03 ~ 0.05 μm). China mostly uses light calcium carbonate. Among them, colloidal calcium carbonate is most easily absorbed by the human body. Co-cooking with ammonium chloride solution decomposes to produce ammonia and carbon dioxide.
2. Uses: can be used as alkaline agent, nutritional supplement, dough regulator, curing agent, yeast food, anti-caking agent, loose agent, starter, gum sugar additive and modifier, white pigment (food surface colorant).
3, dosage: in accordance with China's food additives and nutritional enhancers use of hygienic standards, precipitated calcium carbonate as a loose agent for the configuration of baking powder and canned, generally the variety dosage of 1%. As a food fortifier, it is used in wheat flour and its products in a dosage of 4-8 g/kg, drinking liquid and milk drinks 1-2 g/kg, and infant rice flour 7.5-15 g/kg.
(5) Citric acid
1, nature: citric acid is an important organic acid, also known as citric acid, colorless crystal, often contains a molecule of crystalline water, odorless, has a strong sour taste, easily soluble in water. Its calcium salts are easier to dissolve in cold water than in hot water, and this property is often used to identify and separate citric acid. At room temperature, citric acid is a colorless translucent crystal or white particle or white crystalline powder, odorless, extremely acidic, slightly deliquescious in humid air. It can exist in the form of no hydrate or monohydrate: citric acid crystallizes from hot water to form a hydrate, and crystallization in cold water forms a monohydrate. When heated to 78 °C, monohydrate decomposes to produce a hydrate-free. At 15 degrees Celsius, citric acid can also be dissolved in absolute ethanol. Structurally, citric acid is a tricarboxylic acid compound and therefore has similar physical and chemical properties to other carboxylic acids. When heated to 175 °C it breaks down to produce carbon dioxide and water, leaving some white crystals. Citric acid is a strong organic acid, there are 3 H+ can be ionized; heating can be decomposed into a variety of products, and acid, alkali, glycerin and so on to react.
2, uses: citric acid has a mild and refreshing sour taste, commonly used in a variety of beverages, soda, wine, candy, snacks, biscuits, canned juice, dairy products and other food manufacturing. In all organic acid markets, citric acid has a market share of more than 70%, and so far there is no sour agent that can replace citric acid. Monomolecular crystalline water citric acid is mainly used as an acidic flavoring agent for refreshing drinks, juices, jams, fruit sugars and canned food, etc., and canned foods, and can also be used as an antioxidant in edible oils. At the same time, it improves the sensory properties of food, enhances appetite and promotes the digestion and absorption of calcium and phosphorus substances in the body. Citric acid anhydrous is used in large quantities in solid beverages. Citric acid salts such as calcium citrate and iron citrate are fortified agents that require the addition of calcium and iron ions in some foods. Citric acid esters such as triethyl citrate can be used as non-toxic plasticizers, plastic films for food packaging, and are acidulants and preservatives in the beverage and food industries.
3, dosage: as an acidulant and additive, the national standards do not limit their use, the World Food and Agriculture Organization (FAO) and the World Health Organization (WHO) notified the daily allowable consumption (ADI) is not limited to its use.
(6) Sodium D-iso-ascorbate
1, properties: white crystal, odorless, salty, soluble in water, solubility at room temperature of 16g/100mLH2O, aqueous solution pH of 5-6, aqueous solution is easily oxidized by air, trace amounts of metal ions, heat, light can accelerate its oxidation. Stable in drying, under acidic conditions, hetero-ascorbic acid can be formed. Ascorbic acid is an optical isomer of ascorbic acid (vitamin C) (ascorbic acid is of the D-configuration, ascorbic acid is the L-configuration). The chemical properties of the two are basically similar, but the ascorbic acid is less heat resistant than ascorbic acid, the antioxidant capacity is stronger, and the anticorbic function is only 1/20 of ascorbic acid.
2, uses: D- sodium iso-ascorbate is an important antioxidant preservative in the food industry, which can maintain the color and luster of food, natural flavor, extend shelf life, and without any toxic side effects, in the food industry, mainly used for meat products, fruits, vegetables, canned food, jam, beer, soda, fruit tea, juice, wine, etc.
3, dosage: China's "Food Additives Use Hygiene Standards" (GB 2920-1996) stipulates: can be used for beer, the maximum use of 0.04g / kg, wine, juice drinks, the maximum use of 0.15g / kg; meat products, the maximum use of 0.5g / kg; fruit and vegetable canned, canned meat, jam, frozen fish The maximum use of 1.0g / kg. The "Standard for the Scope and Amount of Use of Food Additives" (1986) of Taiwan Province of China stipulates that the maximum amount of use in food is less than 1.3g/kg. Limit to use as an antioxidant. FAO/WHO (1984) stipulates: lunch meat, pork tenderloin, ham, minced meat, sodium iso-ascorbate alone or in combination with ascorbic acid, ascorbic acid and its salts (in terms of ascorbic acid), the maximum amount of use is 0.5g/kg.
(VII) Tert-butyl hydroquinone (TBHQ)
1. Properties: Also known as tert-butyl hydroquinone, it is a white yellow crystalline powder with a special odor. Melting point 126, 5--128, 5 °C, boiling point 300 °C, slightly soluble in water, easily soluble in organic solvents, and the solubility in oil and water increases with increasing temperature. It is thermally stable and does not form complexes with iron, copper, etc., but can be pink when seen in light or under alkaline conditions.
2, uses: it has a strong antioxidant capacity, has a synergistic effect on other antioxidants. It also has a certain antibacterial effect, inhibiting bacteria, yeast and mold, and sodium chloride has a synergistic effect on its antibacterial effect. TBHQ is very stable to high temperatures, and in fried foods, it can be well used with grease into food and its antioxidant effect, but it is less effective in the process of food baking.
3, dosage: China's "Food Additives Use Hygiene Standards" (GB2760--2007) stipulates: TBHQ can be used for grease, fried food, dried fish products, biscuits, instant noodles, quick-boiled rice, dried fruits, canned and cured meat products, the maximum use of 0.2g / kg. 0.02% TBHQ can improve the oxidation stability of oil and potato chips, the amount of TBHQ in peanut oil is generally 0.02%, and the sausage is added 0.015% TBHQ according to the amount of fat.
(8) Lemon yellow
1, nature: lemon yellow is also known as edible yellow no. 4 (Japan), yellow no. 4 (the United States), azo colorant, not into yellow powder or granules, odorless. Easily soluble in water, 0.1% aqueous solution is yellow, neutral and acidic aqueous solution is golden yellow, the maximum absorption wavelength is 428nm, soluble in glycerol, propylene glycol, slightly soluble in ethanol, insoluble in oil. Edible lemon yellow appearance is orange yellow powder, slightly soluble in alcohol, insoluble in other organic agents, its chemical composition is 3-carboxy-5-hydroxy-1- (p-sulfabenzene)-4- (p-sulfaphenyl azo) o-azatrisodium, the main raw materials for the production of p-aminobenzenesulfonic acid and tartaric acid.
2, uses: lemon yellow in tartaric acid, citric acid is stable, is the most stable colorant, can be used in combination with other pigments, good matching. It is mainly used for the coloring of food, beverages, medicines and cosmetics, and also for the dyeing and manufacturing of wool and silk. Water-soluble synthetic pigment, bright and tender yellow, widely used in ice cream, ice cream, jelly, yogurt, beverages, canned, candy coatings and other coloring.
3. Dosage: According to China's "Hygiene Standards for the Use of Food Additives" (GB2760-1996), it is used for high-sugar juice (taste) or fruit juice (taste) or juice (flavor) beverages, carbonated drinks, prepared wine, candy, pastries on color, canned watermelon sauce, green plum, shrimp (flavor) slices, pickled side dishes, red and green silk, the maximum use of 0.1g/kg; for ice cream, the maximum use of 0.02g/kg. For plant protein drinks, lactic acid bacteria drinks, the maximum dosage of 0.05g/kg.
(9) Caramel color
1. Properties: A complex mixed compound, some of which exist in the form of colloidal aggregates, which can be made alone by heating carbohydrates or synthesized with the participation of edible acids, alkalis and salts. Caramel pigments are usually brownish-black to black liquids or solids with an odor of burnt sugar and a certain bitter taste. Its raw materials are mostly fructose, glucose, invert sugar, sucrose and starch hydrolyzed products or partial hydrolyzed products.
2, uses: caramel pigment is also known as caramel, caramel pigment is a kind of natural colorant with a wide range of applications in the food industry, is an important member of food additives. Caramel coloring is often used in desserts to provide pastries and desserts with a flavor that fills candy or chocolate, or on ice cream and custard. Or as a food melanin, such as cola and other beverages using caramel coloring, and it is also used as a food colorant, it is also the only allowed additive in the whisky industry. Caramel pigment is soluble in water . Caramel color is widely used in soy sauce, vinegar, cooking wine, sauce brine, pickled products, baked food, candy, medicine, carbonated beverages and non-carbonated beverages, etc., and can effectively improve product quality.
3, dosage: suitable for soy sauce, vinegar, cooking wine, sauce brine, pickled products in the amount: the amount of addition 2-5%. As a colorant, it is not limited to use in national standards.
Second, the detection of food additives
Take a number of sample powders, dissolve in distilled water, add two drops of consistent iodine solution to observe whether the color changes, and turn blue to prove the presence of starch.
(2) Calcium carbonate
There are usually a variety of ways to determine calcium content. Typically include instrumental analytical traces and chemical analytical constants. The atomic absorption spectrometry, electrochemical method, photometric analysis, emission spectroscopy, etc. in the instrumental analysis method can determine the content of calcium. Among them, the methods used are EDTA complex titration, acid-base titration, redox and high-temperature calcination.
Calcination method at high temperatures
Find a clean porcelain crucible and weigh it W0. Weigh 2 g of sample to an accuracy of 0.001 g and place in a clean porcelain crucible. Together with the crucible weigh the W1. Put the crucible in the muffle oven and start roasting from low temperature, without lid, stabilize for 20 minutes after 900 degrees, take out and cool it in air below 100 degrees, then cover and cool it to room temperature, weigh W2. Subtract the empty weight again, W2-W0. The mass of calcium oxide is obtained and the content of calcium carbonate is calculated.
Acid-base titration
1, the preparation of NaOH Weigh 40g NaOH, add 5L deionized water, roughly mixed into 0.2mol/L NaOH.
2. Calibration of NaOH 1.0013g of potassium hydrogen phthalate by electronic balance in an Erlenmeyer flask, add 25ml of deionized water, add 3 drops of phenolphthalein dropwise, and titrate with the prepared NaOH solution until the phenolphthalein appears red. The volume V1 used to record the same reason accurately weighed 0.9820g of potassium hydrogen phthalate in an Erlenmeyer flask, added 30ml of deionized water, and added 3 drops of phenolphthalein dropwise. Titrate with the prepared NaOH solution until the phthalate appears red. Record the volume V2 used.
3. Preparation of HCl Take 85ml of concentrated HCl and add distilled water to 5L.
4. Calibration of HCl Remove 25.00ml of HCl in an Erlenmeyer flask, add 3 drops of phenolphthalein dropwise, and calibrate with the calibrated NaOH until the solution becomes red. Record the volume of NaOH used. Assay 3 times in parallel, recording volumes separately.
5. Determination of sample Accurately weigh the sample in an Erlenmeyer flask and add 40.00ml of HCl solution. Full reaction, heated on an electric stove to boiling, co2 removed after 3 minutes to cool, 3 drops of phenolphthalein in an Erlenmeyer flask, titrated with already calibrated NaOH solution until the phenolphthalein appears red. Record the volume used. Three copies are measured in parallel. Record the volume of NaOH used separately.
6. Calculate the content of calcium carbonate.
EDTA complexation titration
1, 0.020mol·l-1EDTA solution preparation Weigh 4.0g of disodium edta in a 500ml beaker, add 200ml of water, warm so that it dissolves completely, transfer to the acid reagent bottle, dilute with water to 500ml, shake well.
2. Calibrate EDTA with CaCO3 as the reference
(1) Prepare 0.020 mol·l-1 calcium standard solution Accurately weigh 110 °C dried CaCO30.50 ~0.55g, placed in a 250ml beaker, moistened with a small amount of water, cover the surface dish, slowly add 6mol/L HCl 5ml to dissolve it, add a small amount of water to dilute, quantitatively transfer to a 250ml volumetric flask, dilute with water to the scale, shake well, calculate its accurate concentration.
(2) Calibration of EDTA solution concentration Pipette 25.00ml calcium standard solution in a 250ml Erlenmeyer flask, add 5ml 6mol/L NaOH solution and a small amount of calcium indicator, shake well, and titrate with EDTA solution until the solution changes from burgundy to pure blue, that is, the end point. Measuring the three points in parallel, the concentration of the EDTA standard solution is calculated, and its relative average deviation is not more than 0.2%.
3. Processing of samples The samples are washed, dried and crushed.
4. Determination of calcium carbonate content in the sample Accurately weigh 0.5000g of the treated sample in a 250ml Erlenmeyer flask, wet with a small amount of water, cover the surface dish, slowly add 1:1HCl 5ml to dissolve it, add 5ml6mol/LNaOH solution, adjust pH = 12-13. Add a small amount of calcium indicator, shake well, and titrate with EDTA solution until the solution changes from burgundy to pure blue, that is, the end point. Three copies are measured in parallel to calculate the content of calcium carbonate in the sample.
The formula for calculating the concentration of EDTA is CEDTA=mCaCO3÷100÷VEDTA×1000 mol·l-1
The formula for calculating the calcium carbonate content in the sample W=VEDTA×CEDTA × 100÷m×100%
(c) Citric acid
Prototyping and solution
PhD: Prepared according to GB 604-77 "Indicator pH Discoloration Determination Method"
Sodium hydroxide (GB 629-81): 1N standard solution, prepared according to GB601-77 "Chemical Reagent Standard Solution Preparation Method".
Determination Procedures Weigh 1.5 g of the specimen (weighed to 0.0002 g), add 40 ml of freshly boiled cold water, dissolve. Add 3 drops of 1% phenolphthalein indicator and titrate with 1 N sodium hydroxide standard solution to a reddish terrestrial color.
Calculate X=V×C×0.06404/m (1-0.08566) ×100.................. (1)
Wherein: X - Citric acid content monohydrate (according to anhydrous), %;
V─— Volume of sodium hydroxide standard solution consumed by titration specimens, mL;
C─— Concentration of sodium hydroxide standard solution, mol/L;
m--— Specimen mass, g;
0.06404- the mass of citric acid in grams equivalent to 1 ml of sodium hydroxide solution [1.000mol/L]; 0.08566── C6H8. The theoretical content of H2O in H2O, i.e. 18/210.14.
(4) D-Isoan ascorbate sodium
1. The solution of this product (1+50) is slowly reduced at 25 °C, and it is easier to carry out when heated.
2, with 0.1mol / L HC1 solution 0.5mL acidification of this product solution 2mL (1 + 50), and add a few drops of sodium nitro ferrocyanide test solution (take sodium nitro ferrocyanide NaFe (HO) (CH) 5·2H2O1g dissolved in 2mL water), add 0.1mol / LNaOH solution 1mL, immediately produce a short blue.
(5) Tert-butylhydroquinone
1. Main instruments and reagents
High performance liquid chromatograph: Agilent 1260; 1260VWD VL UV detector: Agilent; high-speed centrifuge, centrifuge tube, TGL-16G vacuum extraction pump: Shanghai Anting Scientific Instrument Factory; sample vials (15 mL and 2 mL); vortex mixer, etc.
tert-Butylhydroquinone (TBHQ) Standard (German DR): 99% ≥; Acetonitrile (chromatographically pure), purified water; Sample: Soybean oil with TBHQ added.
2. Chromatographic conditions
Column: Alltima C18 reversed-phase column (4.6mm×15cm, 5μm); Mobile phase: V (acetonitrile): V (water) = 90:10; Flow rate: 0.8mL/min; Detection wavelength: 292nm; Column temperature: 25°C; Sample volume: 20μL.
3. Sample pretreatment and measurement
Accurately weigh 1 g (accurate to 0.0001 g) of sample in a 15 mL vial and add 5 mL of acetonitrile. After mixing on a vortex mixer for 1 min, let stand in a water bath at 55 °C for 30 s, vortex mix for 1 min, and then let stand in a water bath at 55 °C for 30 s, take the supernatant in a 2 mL disposable centrifuge tube, centrifuge at 1000 r/min for 10 min. The centrifuged upper layer of the supernatant was filtered in a 2 mL vial with a 0.45 μm organic phase filter membrane to obtain a test solution. Take an appropriate amount of tert-butyl hydroquinone (TBHQ) standard, weigh it precisely, and prepare a solution with a concentration equivalent to the solution of the test product as a control solution.
4. Take 20 μL of the control solution and the test solution, inject it into the liquid chromatograph for determination, and calculate the content according to the peak area according to the external standard method.
(6) Lemon yellow
1. Instruments and reagents
Instruments: UV-1240 or UV-1801 UV-Vis spectrophotometer, volumetric flask
Reagents: 0.5 mg/ml Lemon Yellow Standard Stock Solution, Deionized Water, Ice Lemon Flavored Gatorade (or other beverages containing only lemon yellow food coloring)
2. Experimental steps
Preparation of working curve solution 0.5ml, 1ml, 1.5ml, 2ml, 2.5ml standard solution dissolved in 25ml volumetric flask, deionized water volume.
The absorption curve is drawn, the maximum absorption wavelength is found, the working curve solution with the maximum solubility is removed, and the wavelength scan (210nm-500nm) is performed in the ultraviolet-visible spectrophotometer to find the maximum absorption wavelength.
Determination of the working curve The standard solution prepared in step 1 was measured by a UV-vis spectrophotometer, and the absorbance and concentration were linearly returned to obtain the working curve equation.
Determination of sample content Take the appropriate amount of the drink to be measured, heat the water bath in addition to carbon dioxide, let cool, ultraviolet- visible spectrophotometer to measure the absorption, according to the working curve equation to calculate the content of lemon yellow. (Note: The national standard stipulates that the maximum dosage of lemon yellow in beverages is 0.1g/1kg.)
(7) Caramel color
The absorption ratio of the caramel pigment solution at 280 nm and 560 nm is measured.
Step 2: Weigh the 100 mg sample into a 100 ml volumetric flask, set the volume with water, mix well, and centrifuge if the solution is cloudy. Pipette 5, 0 clear liquid in a 100 ml volume flask, set the volume with water, and mix well. The absorbance of the 0, 1% caramel solution was determined at 560 nm with a suitable spectrophotometer; similarly, the absorbance of the caramel solution diluted by 1: 20 nm was determined at 280 nm. Both assays are based on water as a reference, and the absorption ratio is calculated as follows:
A1×20/A2
A1--- absorbance at 280 nm;
A2---560nm absorbance;
20--- dilution multiple.
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