Quantitative determination of benzoic acid

Objective: to familiarize with the method of quantitative analysis the content of benzoic acid in food products. The essence of the method of determination of benzoic acid and benzoate sodium is reduced to the preparation of the aqueous extract of the studied product, deposition from albuminous substances, the extraction benzoic acid from water extract of chloroform, followed titration. The technique For analysis prepare a water the extract in a volumetric flask to 250 ml of sample product weight 20-50 g (if the product is solid, it is shredded, add on drops of 10 % NaOH solution until an alkaline environment (sample on the Lac Mysovoy the paper). To precipitate proteins add 5-10 ml K4 (Fe(CN) 6 ) and 5-10 ml ZnSC4. The contents of the flask was adjusted to the mark with distilled water, vigorously stirred and after 5 min filtered. Then 100 ml of filtrate is placed in a separatory funnel, neutralized with a solution of HC1 until neutral reaction, then add another 5 ml of HC1. Benzoic acid is extracted four times with chloroform 40-50 ml; the duration of each extraction is 15-20 min.

Stirring is carried out in a small circular motion every 5 min. After each extraction chloroform extraction collected in one flask and then distilled off 3/4 of volume of chloroform on a water bath at 65 °C, after which the rest of the exhaust transferred to a porcelain Cup and evaporated to dryness at a temperature of 40-50 °C. When injected into the extraction of the water layer must the chloroform layer is washed with distilled water twice 5 ml. The residue of benzoic acid in the Cup is dissolved in 30-50 ml alcohol (neutralized to phenolphthalein), add 10 ml distilled water, two or three drops of phenolphthalein and titrated 0.05 mol/DM 3 solution Paon. 1 ml of the NaOH solution corresponds to 0, 0061 g of benzoic acid or 0, 0071 g of sodium benzoate. Massfractionofbenzoicacid ( % )

 

 

where V – volume of NaOH solution used for titration, ml; C – molar concentration of NaOH solution, mol/ DM 3; M – mole molecular weight of benzoic acid, g/ mol; V1 – total prepared solution, ml; V2 – volume of filtrate taken for extraction with chloroform, ml; m is the mass of a sample of the product, The entry in the workbook: confirmation of the presence of benzoic acid; the volume of NaOH solution consumed for titration (V), ml; the molar concentration of NaOH solution (C ), mol/ DM 3; the molecular weight of benzoic acid (M), g/ mol; the total volume of the solution prepared in (V1 ), ml; the volume of filtrate taken for extraction with chloroform (V2 ), ml; the weight of the portion of the product (m), g; mass fraction of benzoic acid (X), %. 30

Control questions

1. The essence of the method of determination of benzoic acid.

2. The solutions used for the deposition of proteins.

3. Than extracted the benzoic acid from the aqueous extract?

4. What is the HCl solution?

5. What dissolve the residue of benzoic acid?

6. The principle of action of preservatives.

7. The purpose of the introduction of preservatives into food products.

 

LABORATORY WORK № 6

 

THE CALCULATION OF THE FORMULATION AND PREPARATION OF NON-ALCOHOLIC BEVERAGE WITH THE USE OF FOOD ADDITIVES

Objective: to learn how to choose colors and flavors, as well as their dosages when cooking soft drink.

Assignment: 1) calculate the recipe to make the drink;

2) prepare the drink: boil sugar syrup; to prepare a citric acid solution; pick up the dosage of the dye and flavoring,

3) to assess the quality of the finished drink to give technological conclusion.

Brief information

Despite the rich assortment of alcoholic and non-alcoholic beverages and a variety of packaging design, the main role for consumers when choice is the quality of the drink. The drink lived up to its name and in demand, it should have a high organoleptic properties, i.e. harmoniously combine color, taste and aroma. In the manufacture of beverages widely used food colorants, flavourings and acidity regulators.

To give the product taste and flavor used food flavourings. Apply them not only to create a wide range of drinks, different aromatics and taste characteristics, but also for the stabilization of these indicators of product, recovery of flavor and aroma lost during processing (particularly during pasteurization), enhancing natural taste and aroma, giving a pronounced sensory indicators tasteless drinks (alcoholic and non-carbonated soft drinks, mineral water); disposal of beverage unpleasant to the consumer tastes, such as aspartame in diet drinks.

In a large assortment of flavors for soft drinks production we can distinguish four main groups: citrus, berry, tropical and others, including the fancy flavors and spices. The undisputed leaders among the flavors are citrus: lemon, lime, orange, tangerine and grapefruit. Flavorings for soft drinks produced in the form of liquids and powders that must be dissolved in the water.

The flavor is a mixture of individual components, including natural aromatics (aldehydes, acetone, ketones, acids, alcohols and other compounds). It is not that other, as essential oils are not soluble in water. Therefore, liquid flavorings, depending on the methods of obtaining easy to use forms of oils are divided into solutions and emulsions. The solutions obtained by deletion or modification of insoluble substances, and then distribute the oil in a food acceptable solvent. The quality and durability of flavor to a large extent are determined by the solvent.

The solvent used is ethanol, isopropyl alcohol, propylene glycol. When using propylene glycol increases the stability and quality of the flavors, 2 to 2.5 times increased shelf life, by reducing volatility reduces the consumption of fragrant substances. The greatest application in the manufacture of soft drinks got the flavorings in the form of emulsions, which combine color, taste and aroma.

Emulsion is a system consisting of one or more liquids (oil, water) dispersed in another liquid medium in the form of fine particles whose size must be from 1 to 2 µm (with larger particles of the emulsion may delaminate When choosing the flavor must be considered the beverage's characteristics (density, acidity). The name of the flavoring is only partially characterizes its aroma, so the smell is usually evaluated by " sniff", and the flavor by tasting flavored sugar syrup. The flavorings in the production of alcoholic and non-alcoholic beverages, not complicates the process. The fragrances in small doses (0.05 to 0.2 %) are introduced together with sugar syrup. After the introduction of flavoring the drink should be mixed thoroughly.

 

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