Effects of processing conditions and storage on honey quality

Abstract

Fresh Kenya crude honey was collected from two districts and analyzed for their physico-chemical properties before and after heat processing at each of the temperatures for 20, 25 and 30 minutes 50° , 55° The physico-chemical properties analyzed included residual diastase (amylase) activity, hydroxmethylfurfural (HMF) content, colour and rate of crystallization. Processed honeys wet~e also analyzed for the same during six months of storage room temperature (18±4°C) , Significant differences at 5% level were found in crystallization rate between all processing temperatures used. Levels of HMF differed significantly (P=0.05) between unheated and heated samples and also between samples heated at 45°C and those processed at other temperatures. Samples heated at 50GC also differed significantly (P=0.05) in HMF content with those heated Generally, increased temperatures resulted in increased HMF production. The co lour- as measured in terms of optical density at 440 nm showed significant differences (p=0.05) between unheated and heated samples, while heated sampled did not differ significantly among themselves. However, there was a positive correlation between increased processing temperature and increased optical density in all samples studied. No significant differences (P=0.05) in diastase activity were found among all honey samples studied, although there were noticeable decreases in diastase residual activity with increased processing temperatures. Increase in storage temperature and/or time resulted in increased rates of HMF production with high temperatures (28°C and 3S-C) showing HMF values above those recommended for table honey (40 ppm) after six months of storage. The rate of diastase inactivation increased with increased storage temperature and/or time. Within four months' storage at 3SoC, the residual diastase activity had been lowered to below number of 8, the minimum recommended for' table honey. The optical density (for colour) increased with increased storage time and/or temperature. High storage temperatures (28- and 3S-C) showed significantly higher (p=o.OS) optical density and visual colour than those at lower temperatures (22° and 18 - 4°C • Increased storage temperature and/or' time resulted in decreased rate of crystallization with most samples stored at 28° and 3SoC showing no crystallization at all after six months of storage. Processing at 55°C for 25-30 minutes and storage at 25-26°C could be recommended as the most appropriate for honey processing and storage.