Table 1.

Different anthocyanin concentrations present in onions and their detection techniques.

Anthocyanins and its derivative	Part used	Detection technique*	Concentration	References
Anthocyanins (cyanidin, peonidin, pelargonidin, delphinidin, and petunidin)	Bulb	HPLC	0.3–0.19 mg/100 g DW	(58)
Anthocyanins (cyanidin, peonidin, pelargonidin, delphinidin, and petunidin)	Bulb	HPLC	1,555–250 mg/kg DW	(59)
Anthocyanin	Peel	pH differential	21.99 mg/g DW	(60)
Anthocyanin	Red onion wastes	pH differential	748–840 mg/100 g	(61)
Total anthocyanin	Red, yellow, and white onion	HPLC/DAD-ESI/MS	(29.99 ± 1.19), (9.64 ± 1.30), and (0.75 ± 0.40) mg 100 g−1	(50)
Anthocyanin (cyanidin, peonidin)	Honeysuckle (HSRO) and sweet Italian red onion (SIRO)	LC-ESI-QTOF-MS	HSRO- 0.103 mg/g SIRO- 0.086 mg/g	(18)
Anthocyanin (cyanidin)	Red onions	UHPLC	0.056 mg/g	(62)
Total anthocyanin	Korean red onions	Colourimetric method	0.02–0.12 mg/g	(63)
Anthocyanin (Cyanidin and delphinidin)	Red and white onion	Colourimetric method	Red onion-0.3587 mg/g White onion- 0.014 mg/g	(64)
Cyanidin, Peonidin, Pelargonidin, Delphinidin, and Petunidin	Bulb	HPLC-MS	0.21–0.45 mg/100 g DW	(65)

*For details, refer to the list of abbreviations.