Identifying Bioactive Compounds from New Zealand Native Honey
Honey is a big industry globally and within New Zealand, this industry is worth about $505.5 million. Honey has been used for centuries for its antibacterial properties to cure many ailments. The aim of this study was to determine the antibacterial properties, arabinogalactan proteins (AGPs) and polyphenolic content of eight different New Zealand honey (clover, bush, mānuka, beech honeydew, pōhutukawa, kānuka, rewarewa, kāmahi and thyme honey) using the growth inhibitory broth microdilution assay, rocket get electrophoresis and liquid chromatography- mass spectrometry methods respectively. Honey ice cream was further formulated to determine if the polyphenolic content was retained during production and consumer acceptance investigated. The results indicated that all honey samples significantly inhibited the growth of bacteria at 25% concentration. Although mānuka honey only required 12.5% concentration to achieve maximum antibacterial inhibition with E. coli, B. subtilis, S. typhimurium, E. faecalis, S. epidermidis and S. aureus, increasing the concentration to 25% did not significantly increase its antibacterial effect. E. coli was greatly affected by the presence of sugar and therefore all honey samples inhibited its growth. Although S. typhimurium and E. faecalis grew exponentially in the presence of high concentration of artificial honey, they were inhibited even at lower concentrations of most honeys, including clover, honeydew and kānuka honeys. P. aeruginosa was the least inhibited by honey. Kāmahi, kānuka, pōhutukawa, mānuka, bush and rewarewa honey had the highest amounts of AGPs. Polyphenols present in the different types of honey varied in concentration. Mānuka, kānuka and pōhutukawa had the highest amount of quercetin, luteolin and gallic acid. Bush and clover honey on the other hand had the highest amount of chrysin, pinocembrin, caffeic acid and pinobanksin. Honey ice cream was further formulated and the major polyphenols were quinic acid, pinocembrin, hydroxybenzoic acid, pinobanksin and chrysin with thyme and clover honey ice cream with highest concentration of polyphenols. Ice cream sweetened with sucrose, as well as pōhutukawa, rewarewa and kāmahi honey were the most liked ice cream in terms of overall liking.