Gamma radiation processing of honey of Mustard, Black seed and Lychee flower: Measurement of antioxidant, antimicrobial, and Fourier transform infrared (FT-IR) spectra

Abstract

Gamma radiation is used in many countries due to combating microorganisms in food. Honey is considered as a reservoir of microbes; hence the purpose of this study was to sterilize honey by applying radiation and evaluate the antioxidant and antibacterial potential of honey after radiation processing. Three types of Bangladeshi origin unifloral honey: mustard (Brassica juncea), Black seed (Nigella sativa) and Lychee (Litchi chinensis) were selected. The raw (unirradiated) black seed honey possessed the highest content of total phenolic and vitamin C contents, accordingly showed significantly higher (p<0.01) free radical scavenging activity compared to others. Radiation processing was found to achieve microbial destruction in honey completely. Significant enhancement of phenolic compound as well as antioxidant activity was observed in the irradiated honey. Moreover, antibacterial potential of all the honeys has been conserved after radiation processing. The statistics showed significant positive correlation among phenolic (R2=0.95) and vitamin C (R2=0.72) content in relation to free radical scavenging activity of honey. FTIR spectroscopy showed no distinct changes in the vibrational intensity of functional groups (-OH, C=H, C=O) indicating nonsignificant changes in the chemistry of the sugar components of honey. Thus, radiation processing of honey could be a useful technique to preserve honey free from microbes and improved beneficial for health compared to unirradiated honey.