: pp. 17-24
Lviv Polytechnic National University
Lviv National Agrarian University

Vegetables’  pollution  by  mercury,  copper,  zinc  and  arsenic  concerning  the  EU  standards  is  not  permitted, whereas in Ukraine it has to be within the limits of permissible concentrations. The urgent task is to develop an express method for controlling  the  concentrations  of  heavy  metals  in  vegetable  production. We  have  investigated  the  electrical  characteristics  of vegetable juices aiming the operative control of heavy metals concentrations in them. The studies were conducted with help of the immitance  method.  For  this  purpose,  an  experimental  installation  was  created;  it  consists  of  the  capacitive  transducer  (a conductivity cell filled with investigated fluid – vegetable juice with various additives), an RLC-meter, a unit for processing results and  control  (computer). RLC-meter  in  asynchronous mode  sends a  test  signal of  sinusoidal  form  to  a  capacitive  transducer.  In response to the test signal on the RLS-meter, the characteristics of the studied liquid are received.

For the samples of carrot juice with different contamination of copper and sodium ions we can admit the smoothness of the change in the active component of electrical conductivity on the frequency of the test signal indicating the absence of frequency-expressed  effects  and  emphasizing  its  ionic  nature.  The  reactive  component  changes  inversely  proportional  correlating  to  the content of impurities.

The main result of current study with help of electrical conductivity method (active and reactive components) at different frequencies can be reduced to the next. To detect the copper (zinc) at the concentration that essentially exceeds the permissible, is enough to fulfill rather simple studies of electrical conductivity active component. 

[1]  Standards  catalogue  ISO  67.080.20  –  Vegetables and  derived  products.  [On-line].  Available:  https://www.iso. org/ics/67.080.20/x/

[2] Forum for the production of fresh fruits and vegetables (http://www.freshfel.org/asp/index.asp)

[3]  Code  Alimentarius.  Int.  Food  Standards.  [On-line]. Available: www.codexalimentarius.net/web/index_en.jsp.

[4] Yu. Posudіn. Methods of non-destructive assessment of quality and safety of agricultural and food products. Kyiv, Ukraine: Arіstei, 2005 (In Ukr.).

[5]  Ye.  Pokhodylo,   P. Stoliarchuk,  Immitance  quality control. Lviv, Ukraine: Lviv Polytechnic Publ. House, 2012. 

[6] Ye. Polіshchuk,  Methods and Means of Measurement of  Non-Electrical  Values.  Lviv,  Ukraine:  Lviv  Polytechnic  Publ. House, 2000 (In Ukr.).

[7]  Yu.  Bobalo,  Z.  Kolodiy,  B.  Stadnyk,  S.  Yatsyshyn, “Development of Noise Measurements. Part 3. Passive Method of Electronic  Elements  Quality  Characterization”,  Sensors  & Transducers, vol. 152, is. 5, p. 164–168, 2013.