experiment for determination the composition of chlorophyll and carotenoids in goji berries. The methodology used by Ruffo et al. (2017) was similar to the methodology adopted in this project because the standard procedures as the use of high-power centrifuge and UV-vis spectrophotometry. In this experiment by Ruffo et al. (2019), the researchers relied on apparatus such as UV-Vis absorption spectra equipment and ORAC assay reader. The procedure entailed mixing 1ml of sodium chloride (5%) with 1g ground sample of goji berries. The solution was then shaken and placed in an ultrasonic bath for a period of 15 minutes. Later on, 3ml of hexane was added to the mixture and left in a dark place overnight. Using the centrifugal machine at 5000 rpm, the mixture was centrifuged for 10 minutes from where the layers were separated and measured using a spectrometer at 460nm. The total carotenoid content was then measured in milligrams and expressed as equivalents of zeaxanthin. Therefore, it can be seen that the procedures and techniques applied by Ruffo et al. (2019) are similar with this project in some aspects of instrumentation even though the methodologies were not precisely the same.
The methodology applied by Wang et al. (2010) for the isolation of carotenoids was comprehensive and revealed an integration of ideas used in other experiments by Ruffo et al. (2019), Islam et al. (2017), and Bertoldi et al. (2019). The experiment entailed a preparative column chromatography for isolating and identifying the contents of samples of goji berries. Despite the similarities among the experiments of these authors, they are all different from the methodology used in this project because column chromatography was not used here. Some of the materials and methods were similar to the previous discussion such as carotenoid standards, centrifuge, and high performance liquid chromatography solvents. In addition, Wang et al. (2010) used YMC C30 reversed-phase column, quadrupole LC/Ms, and photodiode-array detector. The process of extraction and preparation was similar in some aspects to Bertoldi et al. (2019). In this case, 50ml of anhydrous sodium sulphate solution (10%) was added to 10g of ground goji berries and shaken for 10 minutes. After that, 100ml solution of the reagents were added in the recommended ratios and centrifuged for 1 minute at a rate of 4,000 rpm. The residue was extracted while the supernatants were evaporated in a vacuum. Saponification was performed on the solution after adding methanolic sodium hydroxide (40%). In the preparation of chromatography, the researchers mixed 5ml of carotenoid extract with 7.5g of magnesium oxide together with anhydrous sodium sulphate. From here, the determination of carotenoid composition was accomplished through the method of high power liquid chromatography. Peng et al. (2005) also conducted an experiment in their study about the quantification of total carotenoids in goji berries. The similarities observed between the experiment and this project pertained to the use UV-Vis spectrometer and a centrifuge.