Investigation of Temporal Apparent C4 Sugar Change in Manuka Honey

An updated review of functional ingredients of Manuka honey and their value-added innovations

Manuka honey (MH) is a highly prized natural product from the nectar of Leptospermum scoparium flowers. Increased competition on the global market drives MH product innovations. This review updates comparative and non-comparative studies to highlight nutritional, therapeutic, bioengineering, and cosmetic values of MH. MH is a good source of phenolics and unique chemical compounds, such as methylglyoxal, dihydroxyacetone, leptosperin glyoxal, methylsyringate and leptosin. Based on the evidence from in vitro, in vivo and clinical studies, multifunctional bioactive compounds of MH have exhibited anti-oxidative, anti-inflammatory, immunomodulatory, anti-microbial, and anti-cancer activities. There are controversial topics related to MH, such as MH grading, safety/efficacy, implied benefits, and maximum levels of contaminants concerned. Artificial intelligence can optimize MH studies related to chemical analysis, toxicity prediction, multi-functional mechanism exploration and product innovation.

Quality of Commercially Available Manuka Honey Expressed by Pollen Composition, Diastase Activity, and Hydroxymethylfurfural Content

Manuka honey plays a significant role in modern medical applications as an antibacterial, antiviral, and antibiotic agent. However, although the importance of manuka honey is well documented in the literature, information regarding its physicochemical characteristics remains limited. Moreover, so far, only a few papers address this issue in conjunction with the examination of the pollen composition of manuka honey samples. Therefore, in this study, two parameters crucial for honey quality control-the diastase number (DN) and the hydroxymethylfurfural (HMF) content-as well as the melissopalynological analysis of manuka honey, were examined. The research found a large variation in the percentage of Leptospermum scoparium pollen in honeys labeled and sold as manuka honeys. Furthermore, a significant proportion of these honeys was characterized by a low DN. However, since low diastase activity was not associated with low HMF content, manuka honey should not be considered as a honey with naturally low enzymatic activity. Overall, the DN and HMF content results indicate that the quality of commercially available manuka honey is questionable.

Methylglyoxal binds to amines in honey matrix and 2'-methoxyacetophenone is released in gaseous form into the headspace on the heating of manuka honey

Reports on the thermal stability of manuka honey in terms of food processing have been few. This study investigated changes in nine characteristic chemicals of manuka honey during heating. Among these, methylglyoxal (MGO) and 2'-methoxyacetophenone (MAP) were significantly decreased by heating at 90 °C. To elucidate the mechanism for this decrease, artificial honey was prepared from sugars and water with MAP or MGO and then heated. The decrease of MGO was enhanced with l-proline, lysine, or arginine derivatives, accompanied by formation of 2-acetyl-1-pyrroline, MGO-derived lysine dimer, or argpyrimidine, respectively, suggesting that an amino-carbonyl reaction is one pathway for the loss of MGO. The decrease of MAP in the artificial honey depended on the volume of headspace in a vessel. MAP from heated manuka honey was also detected in the gas phase, indicating that MAP was vaporized. Heating could thus reduce the beneficial and/or signature molecules in honey.