title: Effect of different drying methods on chlorophyll, ascorbic acid and antioxidant compounds retention of leaves of Hibiscus sabdariffa L.
abstract: BACKGROUND
  Use of the indigenous, easily accessible leafy vegetable roselle (Hibiscus sabdariffa L.) for value addition is gaining impetus as its nutritive and nutraceutical compounds are exposed by investigations. Being a perishable, storage is challenging, hence different methods of drying have been an attractive alternative for its postharvest usage in foods without much compromising its quality and antioxidant potential.
  
  
  RESULTS
  Room- and freeze-dried samples were found to have best quality in terms of colour, total flavonoid content (18.53 ± 2.39 and 18.66 ± 1.06 g kg(-1) respectively), total phenolic content (17.76 ± 1.93 and 18.91 ± 0.48 g kg(-1)), chlorophyll content (1.59 ± 0.001 and 1.55 ± 0.001 g kg(-1)) and ascorbic acid content (11.11 ± 1.04 and 8.92 ± 0.94 g kg(-1)) compared with those subjected to infrared, crossflow, microwave, oven or sun drying. Samples treated by room and freeze drying retained maximum antioxidant potential as shown by the phosphomolybdate method and the 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging activity and ferric-reducing antioxidant power assays. Cold water and hot water extracts showed significantly higher total phenolic content and total antioxidant activity owing to the greater solubility of phenolics and destruction of cellular components in polar solvents than in organic solvents.
  
  
  CONCLUSIONS
  The data obtained show the potential for retaining quality parameters of roselle leaf under suitable drying methods.
authors.affiliation: Plant Cell Biotechnology Department, CSIR - Central Food Technological Research Institute, Mysore 570 020, India.
authors.forename: Sandopu Sravan
authors.initials: SS
authors.lastname: Kumar
authors.affiliation: Plant Cell Biotechnology Department, CSIR - Central Food Technological Research Institute, Mysore 570 020, India.
authors.forename: Prabhakaran
authors.initials: P
authors.lastname: Manoj
authors.affiliation: Plant Cell Biotechnology Department, CSIR - Central Food Technological Research Institute, Mysore 570 020, India.
authors.forename: Nandini P
authors.initials: NP
authors.lastname: Shetty
authors.affiliation: Plant Cell Biotechnology Department, CSIR - Central Food Technological Research Institute, Mysore 570 020, India.
authors.forename: Parvatam
authors.initials: P
authors.lastname: Giridhar
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D001205:Ascorbic Acid / Q000032:analysis* / Q000737:chemistry; D002734:Chlorophyll / Q000032:analysis* / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis; D005419:Flavonoids / Q000032:analysis / Q000737:chemistry; D063427:Food Quality; D057141:Food, Preserved / Q000032:analysis* / Q000528:radiation effects; D005612:Freeze Drying; D031584:Hibiscus / Q000737:chemistry* / Q000528:radiation effects; D006358:Hot Temperature / Q000009:adverse effects; D006801:Humans; D007194:India; D007259:Infrared Rays / Q000009:adverse effects; D008872:Microwaves / Q000009:adverse effects; D009753:Nutritive Value; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D010860:Pigments, Biological / Q000032:analysis / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018515:Plant Leaves / Q000737:chemistry* / Q000528:radiation effects; D012997:Solvents / Q000737:chemistry
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D010860:Pigments, Biological; D010936:Plant Extracts; D012997:Solvents; D002734:Chlorophyll; D001205:Ascorbic Acid
keywords: antioxidant properties; ascorbic acid; drying methods; microwave drying; roselle; sun drying