Application of gamma irradiation and high-pressure processing on physicochemical, antioxidant and microbiological properties of natural honey

BACKGROUND: Gamma irradiation (0, 2, 4, 8 kGy) and high-pressure processing (HPP at 400 and 600 MPa for 10 and 20 min)
were applied to improve the physicochemical and antioxidant properties and safety of natural polyfloral honey and compared
to heat treatment (60 °C).
RESULTS: Although heat treatment enhanced antioxidant activities, it considerably changed the color of natural honey. In contrast, gamma irradiation and HPP were able to retain the natural color of the honey. Heat treatment and HPP led to a slight
increase in hydroxymethylfurfural (22.3 and 19.7–23.0 mg kg−1
), whereas it was significantly reduced after gamma irradiation
(9.1–13 mg kg−1
). Heat treatment and gamma irradiation at 8 kGy were found to enhance phenolic content, flavonoid content
and antioxidant of natural honey to 83.10 and 49.34 mg GAE 100 g−1
, 4.78 and 2.53 mg QE 100 g−1
, and 88.75% and 82.56%,
respectively. In comparison, HPP (600 MPa/20 min) exhibited less promotion of these health benefits at 40.81 mg GAE 100 g−1
,
1.80 mg QE 100 g−1 and 65.40%. The study also found that inoculated Salmonella spp. was entirely controlled by heat treatment, gamma irradiation at doses above 4 kGy and HPP at 600 MPa for 20 min.
CONCLUSION: Gamma irradiation at 8 kGy and HPP at 600 MPa for 20 min are recommended due to their efficiency in improving the physicochemical qualities, health benefits and microbial safety of natural honey. By comparing these nonthermal processing methods with traditional heat treatment, this study offers valuable insights into optimal preservation strategies for
maintaining quality and safety of natural honey while minimizing undesirable changes.

Keywords: polyfloral honey; gamma irradiation; high-pressure processing; antioxidants; Salmonella spp.