PL224364B1 - Method for prediction the content of extract in fruit juices, especially in apple juice - Google Patents

Description

Description of the invention

The subject of the invention is a method for predicting the extract content in fruit juices, especially apple juice. This method can be used in quality control centers or fruit and vegetable plants producing apple juice.

Refractometric methods are known and used to assess the content of the extract as the basic determinant of apple juice quality. These are instrumental methods that rely on the measurement of the refractive index in aqueous solutions. Measurements are made with instruments called refractometers. The measurement result (extract content) is expressed in degrees Brix [° Bx].

According to the invention, the method of predicting the extract content in fruit juices consists in measuring the value of impedance Z or admittance Y in the frequency range from 100 Hz to 100 kHz or a parallel equivalent electric capacity C _p at frequencies of 100 Hz and 1 kHz or a series equivalent electric capacity C _s at the frequency 100 kHz and then calculating the extract content in apple juice by means of equations of the type y = a ± bx, where y is the equivalent of the extract content E ax and is the measured electrical parameter by which the extract content in apple juice is calculated. The values of "a" and "b" are constant for a specific electrical parameter and a specific measurement frequency, calculated in statistical programs.

The method according to the invention makes it possible to determine in a very short time the extract content of apple juice on the basis of value, impedance or admittance, in the frequency range from 100 Hz to 100 kHz or a parallel equivalent electric capacity at frequencies of 100 Hz and 1 kHz or a series equivalent electric capacity at 100 kHz frequency.

Electrical parameters were measured as follows:

Apple juice was poured into glass tanks (own construction) with dimensions of 75 x 55 x 94 mm, equipped with two plate electrodes made of acid-resistant steel, mounted adjacent to two ₃ opposite (with a smaller area) walls of the tank, apple juice was poured in an amount of 200 cm ³ . The juice samples were then placed in an air conditioning chamber to obtain the desired temperature (20 ° C). After the temperature had stabilized for about 2 hours, the following electrical parameters were measured:

- impedance Z,

- admittance Y,

- parallel equivalent electric capacity C _p ,

- series equivalent electric capacity C _s .

Measurements were made with an HP 4263B type meter at a constant voltage of 200 mV and a frequency ranging from 100 Hz to 100 kHz. The study of the electrical properties of apple juice was carried out according to the in-house developed electrical measuring system for testing the electrical properties of raw materials and food products shown in Fig. 1, where R - resistance, Cp - parallel equivalent electrical capacity, Cs - series equivalent electrical capacity, Z - impedance, M - measuring device.

The subject matter of the invention will be explained in more detail in the working examples and in the attached table No. 1 the regression equations of the extract content as a function of changes in the measured electrical parameters are shown.

P r z k ł a d 1

We measure the impedance Z, apple juice at a frequency of 100 Hz. The obtained value is 215.83 Ω, it is calculated on the basis of the mathematical dependence, determined by the equation E = 23.984257 - 0.072413 x Z, the predicted content of extract E will be: 23.984257 0.072413 x 215.83 = 8.36 ° Bx.

P r z k ł a d 2

We measure the admittance of apple juice at a frequency of 100 kHz. The obtained value is 5.8891 mS, calculated on the basis of the mathematical dependence, determined by the equation E = -3.723068 + 2.628732 x Y, the predicted content of extract E will be: -3.723068 + 2.628732 x 5.8891 = 11, 76 ° Bx.

P r z k ł a d 3

We measure the parallel equivalent electrical capacity C _p of apple juice at a frequency of 1 kHz. The obtained value is 3.0174 nF that is calculated from the relationship

According to the equation E = 1.564034 + 2.859966 x Cp, the predicted content of extract E will be: 1.564034 + 2.859966 x 3.0174 = 10.19 ° Bx.

P r z k ł a d 4

We measure the serial equivalent capacitance C _s of apple juice at a frequency of 100 kHz. The obtained value is 4.7968 pF, calculated on the basis of the mathematical dependence, determined by the equation E = 4.672325 + 1.370702 x Cs, the predicted content of extract E will be: 4.672325 + 1.370702 x 4.7968 = 11.25 ° Bx. The measured values of the extract in the apple juices given in Examples 1, 2, 3, 4 by means of a refractometer were respectively: 8.08; 12.12; 10.10 and 12.12 ° Bx ”.

T a b e l a No. 1.

extract content as a function of changes in impedance (Z), admittance (Y), parallel equivalent electric capacity (Cp) and series equivalent electric capacity (Cs) of apple juice

Frequency Parameter electric r α Regression equations 100-100 kHz WITH -0.876 0.000 ** E = 23.984257 - 0.072413 x Z Y 0.868 0.000 ** E = -3.723068 + 2.628732 x Y 100 Hz Cp 0.865 0.000 ** E = 1.616014 + 0.042947 x Cp 1 kHz Cp 0.906 0.000 ** E = 1.564034 + 2.859966 x Cp 100 kHz Cs 0.762 0.000 ** E = 4.672325 + 1.370702 x Cs

Explanations to Table 1: E - extract content: r - correlation coefficient; α - significance level, calculated ** - significance of differences (α <0.01)

Claims (1)

Patent claim Method for predicting the extract content of fruit juices, especially apple juice, characterized by measuring impedance or admittance in the frequency range from 100 Hz to 100 kHz or a parallel equivalent electric capacity, at frequencies of 100 Hz and 1 kHz or a series equivalent capacity electricity, at a frequency of 100 kHz and then calculates using the equations of the type y = a ± bx, the extract content in the juice where y is the equivalent of the extract content E ax is the measured electrical parameter, while the values of "a" and "b" are constant for a given parameter and the specified measuring frequency, calculated in statistical programs.