EXTRACTION AND QUANTIFICATION OF ANTHOCYANINS FROM YOGURT

Anthocyanins are red to blue hydrophilic pigments naturally present in plants. They are found in vegetables, leaves, and fruits. Red cabbage (Brassica oleracea) is a vegetable with high nutritional value, rich in anthocyanins and phenolic compounds. The red cabbage anthocyanins are very complex and may have in their structure more than two sugars in addition to cinnamic acid molecules. More than 30 anthocyanins were found in red cabbage extract, mainly acylated cyanidin-3-diglucoside-5-glycoside derivatives. Due to the potential bioactivity and the color range, these pigments have been used in several processed foods such as yogurts, baked products, and cereals. Anthocyanins are also known for their interaction with various proteins. Therefore, the recovery of these pigments from dairy matrices may be challenging. The present work aims to validate an extraction method of anthocyanins from yogurt. A commercial natural yogurt was colored with a dye prepared by complex coacervation of red cabbage anthocyanins and egg white protein (1.5% protein at pH 3.5) and spray dried. To evaluate the recovery of anthocyanins, two levels of addition of the dye were used (2 and 3 g/170 g yogurt). The extraction of anthocyanins from the dye and the yogurt was carried out with 10 mL of methanol 1% HCl in a vortex for 2 min. After centrifugation at 6722g for 15 min at 3 °C, the supernatant was transferred to a round bottom flask. The extraction was repeated twice, the supernatants were combined, and the methanol was evaporated in a rotary evaporator (T <40 °C). The anthocyanins were determined by HPLC-DAD and quantified as cyanidin-3-glucoside equivalent. Four anthocyanins were separated, and three were identified and quantified: cyanidin 3,5-di-glucoside, cyanidin 3- (caffeoyl)(coumaryl)glucosyl-5-glucoside, and cyanidin 3-(caffeoyl)(sinapyll)glucoside). The major compound was cyanidin 3-(caffeoyl)(coumaryl)glucosyl-5-glucoside, and its relative content was similar in all the samples (54-56%). The concentration of the 3 identified anthocyanins and total anthocyanin content were considered to determine the anthocyanins' recovery. the The average recovery was 101% for level 1, and 89% for level 2. Anthocyanins from red cabbage were not degraded under the tested conditions.