title: Effect of high hydrostatic pressure on antimicrobial activity and quality of Manuka honey.
abstract: The antimicrobial activity of Manuka honey is of major interest to beekeepers and the honey industry. In this study, the effect of high hydrostatic pressure and thermal treatments on antimicrobial activity and quality parameters (principally, diastase number and hydroxymethylfurfural levels (HMF)) of Manuka honey were investigated. The honey was subjected to different pressures (100-800MPa) at 25°C for a range of holding times (15-120min). The antimicrobial activity was found to increase with applied pressure for a given holding time, while the diastase number and HMF levels remained, more or less, unaffected. The percentage inhibition in microbial growth correlated linearly (R(2)=0.94) with methyglyoxal concentration in the honey after treatment over the entire range of pressure, temperature and holding times studied. Maximum percentage inhibition (78.83%) was achieved when honey was subjected to 800MPa compared to the control (57.93%). Thermal treatments at higher temperatures were found to have a detrimental effect on antimicrobial activity based on percentage inhibition as well as methylglyoxal content. Thus, it can be concluded that the levels of methylglyoxal, and therefore the antimicrobial effect of Manuka honey, can be enhanced by using high pressure processing without adversely affecting honey quality.
authors.affiliation: Department of Food and Nutritional Sciences, University of Reading, Whiteknights P.O. Box 226, Reading RG6 6AP, UK. nhabsi@hotmail.com
authors.forename: Nasser A
authors.initials: NA
authors.lastname: Al-Habsi
authors.forename: Keshavan
authors.initials: K
authors.lastname: Niranjan
mesh_terms: D000681:Amylases / Q000032:analysis; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D006722:Honey / Q000032:analysis*; D006874:Hydrostatic Pressure; D008826:Microbial Sensitivity Tests; D011786:Quality Control; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D000681:Amylases