Fingerprints Of Phenolic Compounds, Abscisic Acid And Proteins In Loquat Honeys

As a natural supplement with high nutritional value and anti-inflammatory, antioxidantproperties, honey is largely used in medical treatment and food processing procedure. However,increasingly adulterated methods have been used to pursue more lawless interests, whichincreased the difficulty for honey adulteration detection, especially in the expensive monofloralhoney identification. A range of minor constituents, such as flavonoids, phenolic acids, abscisicacid and proteins, can be regarded as indicators of botanical origins and authenticity ofmonofloral honey for their considerable different distribution. This work aims to analyzephenolic compounds, abscisic acid and proteins in honey, to establish related fingerprints ofloquat honeys and provide the basis for loquat honey adulteration. The major outcomes asfollows:1. Exploration of experimental conditions: extraction of phenolic compounds and abscisic acid,and the detection condition of high performance liquid chromatography (HPLC). Separationswere carried out on a column (SHIM-PACK VP-ODS C18) using methanol and5%formicacid-water solution (v/v) within77min.14kinds of phenolic compounds such as gallic acid,p-coumaric acid, apigenin were analyzed by HPLC-DAD. Results showed that there aresignificant differences in the contents of abscisic acid and phenolic compounds among differentsamples. The content of abscisic acid was the lowest in osmanthus honey while the highest inlichee honey. Total phenolic contents varied from325.3μg/100g to2260.8μg/100g honey.Among them,12phenolic compounds were detected except keampferol and apigenin.2. Detection of phenolic compounds and identification of loquat honey adulteration:10differentbands of loquat honeys from5different provinces of China and other12honeys were analyzedby HPLC-DAD. Then SPSS19.0and Minitab15.0were used to make cluster analysis to eachcompound to identify botanical origins and adulterated level of loquat honey. Results indicatedthat total phenolic contents of10brands of loquat honeys varied from302.5μg/100g to580.3μg/100g. Loquat honey that spiked with more than10%rape honey could be identified by clusteranalysis. 3. Construction and validation of phenolic fingerprint of loquat honeys: Fingerprint of loquathoneys was established by the Similarity Evaluation System for Chromatographic Fingerprint ofTraditional Chinese Medicine (Version2004A), then the reference fingerprint was verified by thedata of loquat honeys spiked with different concentrations of rape honey. Meanwhile, similaritiesof loquat honey reference fingerprint and other10honey samples were analyzed to discriminatedifferent botanical origins. Results demonstrated that similarity analysis could identify loquathoney spiked with more than30%rape honey and distinguish loquat honey from osmanthushoney, linden honey, lichee honey, longan honey and rape honey.4. Protein fingerprinting of honeys: protein extraction methods were explored and Bradfordprotein quantitative kit was used to evaluate protein contents of9loquat honeys and other17honeys. Then SDS-PAGE was used to construct protein fingerprint of loquat honeys. Resultsindicated that the protein molecular weights of all samples mainly focused from20.1kDa to66.4kDa and the protein patterns were varied among different honey samples. Loquat honeycontained3mark bands at26kDa,39kDa,97kDa. Lichee honey and longan honey had6and2mark bands respectively. Linden honey and acacia honey had mark bands at88kDa. Thesecharacteristic bands could be used to evaluate botanical origins of unifloral honeys.In conclusion, this research focused on the fast detection of abscisic acid, phenolic compoundsand proteins. The related fingerprints of loquat honey could be used for the identification andauthentication of monofloral honey which are important for functional analysis and qualitycontrol of honey.