The dissertation is devoted to the improvement of methodological and metrological assurance of quality control of vegetables and juices from them on the basis of their electro physical parameters analysis with the help of virtual means of immitance control.
The first section analyzes the methods for the qualitative and quantitative composition of food products. Measuring methods of analysis are based on the physical, chemical and biological properties of the substance. The described methods are briefly described; their advantages and disadvantages are indicated. Electrochemical methods, which are related to changes in structure, chemical composition and concentration, are shown to be effective and provide qualitative and quantitative analysis of substances in gas, liquid or solid state. Informative parameters, in this case, are electrical parameters.
In the second section, a comparative analysis of the normative base of Ukraine was carried out in order to approximate the legislation on quality and safety of vegetables and their products to the standards of international law.
To optimize the overall quality index, it is proposed to use the mathematical apparatus of the theory of fuzzy sets, since the characteristics of the product must be in a certain range. As a result, several mathematical models for the complex evaluation of the quality of agricultural products for fuzzy constraints are constructed:
I model is a model for identifying vegetables with the highest content of fiber, carbohydrates and proteins, depending on the amount of mineral fertilizers (maximum value of the function defining a complex quality index);
II Model - a model for achieving the maximum weight of agricultural products (maximum value of the function of mass depending on mineral fertilizers);
III model - a model for ensuring the cultivation of agricultural products with specified parameters of the proportion of nutrients (carbohydrates, proteins);
IV Model is a model of safety of vegetables, that is, a model for assessing the safety of products in relation to its contamination by heavy metals.
Based on mathematical analysis using fuzzy set theory, the effect of mineral fertilizers on the content of nutrients (fiber, carbohydrates, proteins) has been studied. In this case, the problem is solved in three stages:
1) Approximation of the results of the influence of mineral fertilizers on the content of nutrients
2) Simplex - method. Finding the parameters w0 and d0
3) The solution of the system of inequalities with all the desired results - the brand of mineral fertilizers, mathematical parameters λ
Calculation of the goal affiliation function and constraints for a complete picture of the solution of a mathematical problem.
In the third section, a processing of the results was developed.
In conductivity cell was placed model liquids - vegetable juices with impurities of heavy metals. The dependences of the active and reactive components of electrical conductivity of vegetable juice with impurities of copper ions and sodium ions on the frequency of the electromagnetic field of 50Hz-100kHz were studied. It was found on the basis of experimental study:
1) As the frequency of the test signal increases, the active component becomes constant (independent of frequency), and the reactive component approaches zero. As the purpose of research is complex conductivity, I consider research on high frequencies uninformative.
2) At frequencies below 1000 Hz, the experimentally obtained inverse dependence of the active and reactive components of conductivity, which provides information on the quality of juice without additives.
3) In the presence of heavy metal impurities in the controlled juice sample, using immittance measurements, it is possible to prove the efficiency of this method for qualitative and quantitative analysis of carrot juice.
The fourth chapter presents a developed virtual means for measuring the imitation of vegetable juice was described.
For immitance control of vegetable juice quality indicators, a virtual measuring device based on the LabVIEW hardware platform and a compatible NI USB 6009 unit was proposed and implemented. This enabled the rapid analysis of the juice content of the mineral substances by electrical parameters. Thus, in production conditions, at a negligible cost, you can quickly control the quality of vegetables from which the juice is obtained.
The virtual device consists of: a PC with LabVIEW software, the mentioned NI USB 6009 block and a conductivity cell with juice used to determine the content of heavy metals in this juice.
