Determination of Antioxidant Capacity, Total Phenolics and Antimicrobial Properties of Spray-Dried Guava Extract for Value-Added Processing

To explore the potential use of Guava as a functional food ingredient, aqueous guava extract was filtered to remove insoluble material; the soluble extract was spray-dried with the addition of 7% maltodextrin. Spray dried Guava concentrate showed increased levels of antioxidant capacity (2, 2-diphenyl-1-picrylhydrazyl DPPH assay 3.2 fold) and total phenolics (2.0 fold) but low levels of flavinoids. The addition of maltodextrin during spray-drying resulted in the formation of certain unresolved peaks analyzed by HPLC due to dilution effect, the redistribution of molecular weight is likely beneficial for in vivo absorption and increase its bioavailability. Spray-drying concentration also increased the proportion of ascorbic acid content (118.6 mg/100g) of guava powder and showed effective antimicrobial activity against Shigella (MIC 11mg/ml), E coli (MIC 8 mg/ml) and Candida spp. (MIC<1 mg/ml). The proximate and physiochemical properties showed good quality and increased solubility of guava powder compared to plain guava extract. Overall the spray-dried Guava powder may be a good source of natural antioxidants and profoundly increase use of Guava in value added processing and dietary intake.