The objects of the study were Sauvignon Blanc grapes grown in "Vinnye Podvorye Stara Grek" LLC (Krasnodar region, Anapa district, Vityazevo village).
This grape is characterized as technical and had the following characteristics: 21,6 ± 1,5 (vol/vol) sugar; 26 ± 1,5 °Brix; pH 3,53 ± 0,05; total acidity 6,4 ± 0,5 (g/cm3). These values are considered optimal for the production of good quality white wine.
The grapes were hand-picked. After removing the crests, the grapes were separated into two parts, one of which was chilled to a preset cryomaceration temperature in a special freezer installed with a temperature control sensor. The portion of grapes underwent a slow cryomaceration process at -40°C, with a standard deviation of ± 0.5°C for 8 hours to promote the formation of large ice crystals. Frozen grapes were manually separated from the crests.
Ultrasonic treatment was performed using a Wiggens UE22SFD ultrasonic unit at 40kHz. The grape sample was placed in a clear zip-lock bag and then treated in an ultrasonic bath at different times (1–15 minutes) and temperatures (-20°C-(-60°C)) but at the same power to obtain information on potential process transferability. All treatments were performed in at least three repeats.
Studies of chromatic parameters were realized in the laboratory of Technochemical Control of Anapa Agricultural Technical School using a spectrophotometer Unico 1201.
The principle of operation of the spectrophotometer is based on the comparison of the light flux F0, which passed through the solution or comparison solution (blank solution), in relation to which the measurement is made, and the light flux F, which passed through the solution under study. The light fluxes F0 and F are converted by the photodetector into electrical signals Uo, U. Also measured is Ut - a signal from the unlit receiver. According to the values of these signals, the microprocessor of the spectrophotometer calculates and displays the measurement result in the units of transmittance, optical density or concentration depending on the selected measurement mode [4].
The optical characteristic designations are expressed as intensity(I), tint(T) and yellowness(G).
The method is based on the spectrophotometric method, which allows calculating tristimulus values and trichromatic coefficients necessary for coloration designation (ISS, CIE)
The share of yellow pigment D420 depends on the mass concentration of degradation products of tannins and anthocyanins. The contribution of the red component (D520) is provided by the content of free anthocyanins in the form of flavylium cations and anthocyanin-tannin complex. The blue pigment (D620) is formed under the influence of free anthocyanins in quinone form or a complex of tannins and anthocyanins.
The linking of spectrophotometric indices with organoleptic, as well as their classification for quality assessment, is presented in the methodology of P/Sudraud in 1958 [4]. He proposed two indicators for calculation: tint and intensity at both 420 and 520 nm using the formulas 1 and 2
$$I={D}_{420}+{D}_{520};$$
1
$$T=\frac{{D}_{420}}{{D}_{520}};$$
2
White wines and grape juice are characterized by a two-component color created by monomeric anthocyanins and colored condensation products of phenolic substances, which are characterized by absorption maxima at wavelengths of 520 and 420 nm
The experimental samples of the obtained juices were selected based on the intermediate results: sample #1 (SB1) - control; sample #2 (SB2) - without application of cryomaceration, ultrasonic processing for 5 minutes at 20°C; sample #3 (SB*3) - with application of cryomaceration, ultrasonic processing for 5 minutes at 20°C; sample #4 (SB4) - without application of cryomaceration, ultrasonic processing for 15 minutes at 20°C; sample #5 (SB*5) - with application of cryomaceration, ultrasonic processing for 15 minutes at 20°C; sample #6 (SB6) - without cryomaceration, ultrasound processing for 5 minutes at 40°C; sample #7 (SB*7) - with cryomaceration, ultrasound processing for 5 minutes at 40°C; sample #8 (SB8) - without cryomaceration, ultrasound processing for 15 minutes at 40°C; sample #9 (SB*9) - with cryomaceration, ultrasound processing for 15 minutes at 40°C; sample #10 (SB10) - without cryomaceration, ultrasound processing for 5 minutes at 60°C; sample #11 (SB*11) - with cryomaceration, ultrasound processing for 5 minutes at 60°C; sample #12 (SB12) - without cryomaceration, ultrasound processing for 15 minutes at 60°C; sample #13 (SB*13) - with cryomaceration, ultrasound processing for 15 minutes at 60°C.