Multi mixer vortex

TAC was determined by UV-visible spectrophotometry, following the pH differential methodology proposed by Rapisarda et al. (2000) [39 (link)]. An amount of 0.3 g of lyophilized sample was placed in a 15 mL centrifuge tube; 5 mL of pH 1.0 buffer (KCl 0.2 N and HCl 0.2 N) was added and stirred in a Mistral Multi-Mixer vortex (Melrose Park, IL, USA) for 5 min then in a Cole-Parmer model 8892 ultrasound bath (Chicago, IL, USA) and finally centrifuged at 5500 rpm for 10 min. The supernatant was separated and transferred to a 25 mL amber volumetric balloon. This procedure was repeated three more times, and the mixture was brought to volume with the pH 1.0 buffer solution. Extraction with pH 4.5 buffer (CH₃COONa 1M and HCl 1N) was performed using the same methodology. The anthocyanin quantification was performed by measuring the absorbance in the extracts (pH 1.0 and 4.5) at two wavelengths (510 and 700 nm) on a Shimadzu model 2600 spectrophotometer (Shimadzu, Kyoto, Japan). The recovery of the compounds was performed with repeated cycles. Seven extraction cycles were necessary to obtain 100% TAC recovery. The TAC was calculated by the absorbance differences between pH 1.0 and pH 4.5, as described in the equation (Equation (2)):
The TAC results are expressed as milligrams of cyanidin-3-glucoside chloride per gram of dry sample (mg cy-3-glu/g DW).

TAC was calculated by UV-visible spectrophotometry, following the pH differential methodology proposed by [59 (link)]. An amount weighing 0.3 g of lyophilized sample was placed in a 15mL centrifuge tube; 5 mL of pH 1.0 buffer (KCl 0.2 N and HCl 0.2 N) was added and stirred in a Mistral Multi-Mixer vortex (Melrose Park, IL, USA) for 5 min then in a Cole Palmer model 8892 ultrasound bath (Chicago, IL, USA) and centrifuged at 5500 rpm for 10 min. The supernatant was transferred to a 25 mL amber volumetric balloon. This procedure was repeated three more times, and the mixture was brought to volume with the pH 1.0 buffer solution. Extraction with pH 4.5 buffer (CH₃COONa 1M and HCl 1N) was performed using the same methodology. Quantification was performed by measuring the absorbance in the extracts (pH 1.0 and 4.5) at two wavelengths (510 and 700 nm) by a Shimadzu UV-VIS model 2600 spectrophotometer (Shimadzu, Kyoto, Japan). Seven extraction cycles were needed to reach 100% TAC recovery. Results were expressed as milligrams of cyanidin-3-glucoside chloride per gram of dry weight (mg cy-3-glu g⁻¹ DW).