In order to address the techniques where agitators are used within the methods for food analysis, it is necessary to know the meaning of the term “food”, by which is understood any substance that is consumed for its nutritional value. Foods contain essential nutrients such as fats, proteins, vitamins, and minerals, which are analyzed to determine the composition of the food. Foods may be obtained from:
- Animal or plant origin.
- Environmental fungi and bacteria are also used in the preparation of fermented foods and pickles (bread with yeast, cheese, etc.).
- Beverages such as juices, infusions and soft drinks.
Drinks are liquids to drink, including tea, coffee, spirits, beer, juices or soft drinks; water is generally excluded. And, for non-alcoholic beverages, the most important types are: ready-to-drink flavored beverages (almost always carbonated), ready-to-drink beverages containing fruit or fruit juices, and beverages that are diluted for consumption.
Thus, foods may have a solid (fruit, meat, vegetables, or even frozen liquids—ice cream) and a liquid (beverages) shape. In addition, some inorganic substances, such as salt or bicarbonate, are incorporated into these foods and used to store or chemically modify an ingredient, that is, they are used as food additives.
Given the diversity of foods, their composition and their presentation, it is not surprising that the methods of analysis applied are very varied, and that they respond to very specific objectives, which may be nutritional analysis, additives, microbiological or contaminants. The instrumentation used for these analyzes can be as complex as a mass spectrometer or high-efficiency liquid chromatograph. However, as a preliminary step to the final analysis, the sample is usually prepared where the use of shakers is common, such as in pH measurements and the analysis of certain anions such as chloride, nitrite and nitrate.
Analysis of the degree of acidity of foods
The pH is one of the most widespread measurements in any laboratory of analysis, and it is also performed in the evaluation of food. In typical procedure, the pH meter should be calibrated according to the manufacturer’s instructions with at least two buffer solutions, while stirring with the magnetic stirrer. Generally, the pH meter is required to include a temperature correction system. Typical sample preparation procedures include:
- Liquid products: it is recommended to mix the laboratory sample carefully until it is homogeneous.
- Dense or semi-dense products: it is suggested to mix part of the laboratory sample and grind it, if necessary, with a blender or mortar.
- If the product obtained is still too thick, it is suggested to add an equal volume of distilled water and mix well.
This procedure for sample preparation, homogenization and dilution with distilled water can be assisted with a magnetic, mechanical or shaker agitator. The important thing of the preparation is to balance the food sample with the solution, so that the activity of the hydrogen ions to be measured is representative. Finally, a volume of the prepared sample sufficient to immerse the electrodes is used as aliquot, depending on the equipment used.
Determination of chloride, nitrates and nitrites
Many foods, such as cheese and meat products, are added sodium chloride to modulate taste. Therefore, the chloride analysis is an indicator of the amount of salt added to the food. In general, the methods use extraction of an aliquot of the sample with hot water, agitation, and protein precipitation. After filtration and acidification, an excess of silver nitrate solution is added to the extract and the excess is titrated with a solution of potassium thiocyanate.
Nitrates and nitrites are food additives widely used in meat products such as sausages, as preservatives (to prevent the development of undesirable bacteria in the product) and to improve aroma and maintain color. However, nitrates and nitrites can be toxic, so their content in food needs to be monitored. For the analysis, an appropriate hot solvent is added to the food sample and stirred to extract the ions, as a step prior to the determination, which proceeds by spectrophotometric methods.
The food analysis with shaker shakers from Kalstein
Kalstein shaker shakers can be used in food laboratories where sample shaking is required as one of the previous steps for final determination. These teams will become the allies of the analysts, since they provide certain functionalities such as: scheduling of the time of agitation and revolutions; possibility of placing several samples in agitation which is necessary for studies of the repeatability of the method; and from the point of view of the hardware, the motor is silent and with few maintenance requirements. To review these devices for pricing, purchase, and additional technical information, refer to the HERE