The experimental results are expecting for the efficient extraction of betanin from beets. The UV-Vis absorption spectra of red beet extracts at different percentages of the solvents used are visible in the figure below (Figure 5). The shapes of the spectra show two peak centers (shoulder) at the wavelengths shown in the table below (Table 1).
From the results that we found (Table 1), we notice that betanin has an absorption maximum varying from 480nm to 540nm (Figure 5) and indeed our found values confirm the data of the literature16,17. As a result, when the binary mixture (Ethanol-Water) is used to extract betnin from red beet with a high percentage of water (80%), we’ve found an absorption band at 535nm and that it is the same value found when using a mixture (Ethanol-Water) with a low percentage of water (20%). For the mixture (Ethanol-Water) content 40% of water and 60% of ethanol, the maximum absorption wavelength appears at 539nm, however, for 60% water and 40% ethanol, the maximum absorption wavelength appears at 537nm. According to researches results16,17, they showed that the maximum absorption limit of betanin occurs at a wavelength of 538nm at pH 5. In addition, they concluded that the aqueous extracts mainly contain betanidine and that the ethanolic extract mainly contains betanin, where a strong absorption band is observed at about 530nm in the visible range for beetroot juice which has been attributed to the betanin pigment.
In addition, an absorption band is observed at 532nm in the visible region using ethanol as a solvent. In addition, an absorption band at approximately 542nm with the intensity of absorption maxima for aqueous extracts is approximately equal, greater than the ethanolic extract. Thus, the researchers concluded that for the aqueous extract the second band had an absorption maximum at 515nm and for the aqueous extract at 509nm. These bands are only seen in the highly concentrated extract, and it disappears when the solution is diluted. Indeed, our analysis results by UV-Visible absorption spectrophotometry confirm their results.
For the absorbance given in Table 1, when using a mixture (Ethanol-Water) with a high percentage of water, the absorbance value exceeds 2 moles-1.cm-1; this explains why betanin is soluble in a mixture (ethanol-water) with a high percentage of water (80% water-20% ethanol). It is also noted that the quantities extracted from beet betanin are variable depending on the percentages of solvents used. The solvents (Ethanol-Water) used with a high percentage of water can extract a large amount of betanin from beetroot, i.e. approximately 3.42.10-4g/ml.
On the other hand, the UV-Vis emission spectra of beet extracts with the same percentages of solvents used are visible in Figure 6. It is known that betanin absorbs at 537 nm and emits at a wavelength longer than that absorbed. In order to know the value of the wavelength in which it will be emitted, we have chosen an emission range varying from 480 nm to 900nm, so that the value of the wavelength necessary to make this molecule excited must be less than 537nm. From the emission spectra obtained, it is observed that when a mixture (Ethanol-Water) with a small percentage of ethanol is used, the emission peak of this molecule appears at 537nm which is the same absorbed value. Also, when using a mixture (Ethanol-Water) with a high percentage of ethanol, this peak disappears, where it appears at 800nm. Therefore, we can say that the maximum betanin emission limit occurs at a wavelength of 800nm when using a mixture (Ethanol-Water) with high percentages of ethanol and low in water.
TABLE 1 Values of % in Ethanol /% in water (XEthanol, Xwater), volume of the extract in betanin (Ve), mass of solid beetroot (MBeetroot), calculated mass of betanin (MBetanin), wavelengths maximum absorbed (λmax1,2) and maximum absorbances (Amax1,2)
XEthanol
|
80%
|
60%
|
40%
|
20%
|
Xwater
|
20%
|
40%
|
60%
|
80%
|
Ve(ml)
|
40,8
|
31,2
|
31,2
|
40,8
|
MBeetroot(g)
|
40
|
40
|
40
|
40
|
λmax1Absobed(nm)
|
478,5
|
481,5
|
480,5
|
480,5
|
Amax1
|
1,502
|
1,070
|
2,787
|
2,734
|
λmax2Absorbed(nm)
|
535
|
539
|
537
|
535
|
Amax2
|
1,395
|
1,279
|
2,872
|
2,548
|
MBetanin(g/ml)
|
1,88.10-4
|
1,2.10-4
|
2,75.10-4
|
3,42.10-4
|