Quality of stingless bee honey based on volatile organic compounds and gas released

Abstract

The aim of this study is to investigate the volatile organic compound released by stingless bee honey stored at room temperature (≈24°C) for 10 days and how yeast can influence the stingless bee honey quality. A newly harvested stingless bee honey is divided into 8 samples with each containing 100 ml. Each sample is filled into a glass bottle and 8 samples are considered for 8 different days of evaluation. Gas produced by the samples are collected and analyzed using FTIR coupled with White Gas Cell. The spectrum analysis is done by comparing the spectrum of volatile compound with the infrared fingerprint spectral characteristics from Infrared Analysis Inc. database library via Perkin Elmer's spectrum software. Ethanol, methanol, methane, carbon dioxide, water vapour, and ethyl acetate were found to be released by the stingless honey samples. The bands area were identified in order to calculate the concentration of volatile compounds in the honey's gas. The trend of each of the volatile gasses can be seen from Day-1 until Day-8 of evaluation. To study the presence of yeast, 10 g of stingless bee honey is incubated overnight in nutrient broth followed by centrifuging 1.5 ml of the culture broth repeatedly to obtain cell pellet for VPSEM analysis. VPSEM results indicated that morphology of yeast found in the honey sample. Ethanol concentration found to decrease by time however detailed analysis revealed that sample with the presence of yeast shows an increase of ethanol deliberated by the stingless bee honey. This result affirmed that the presence of yeast may facilitate the further alcoholic fermentation in stingless bee honey by which affecting the sensory value of the stingless bee honey.