Optimisation of processing conditions and quality evaluation of honey mead

Abstract

Honey based beverages are the oldest known fermented drinks. Fermentation of these beverages is a time consuming process with the average fermentation time for honey mead is 264 hours (11 days). The aim of this study was to develop a method to reduce the fermentation time of honey mead. In this research, the effects of type of inoculum, inoculum level and the addition nutritional supplements were investigated. Honey was dissolved in sterile water and pasteurised at 65°C for 10 minutes. The samples were inoculated with 1 and 2g yeast of strains EC1118 and 71B. The effect of no nutrition or with DAP (diammonium phosphate) or lupin flour as nutritional (nitrogen) supplement was investigated. Analysis of the amount of ethanol present in the honey mead was performed by using a GC-FID according to the methods used by (Debebe, Redi-Abshiro, & Chandravanshi, 2017). The highest concentration of ethanol 12.79 % (w/w) was obtained after fermenting with 71B yeast strain for 96 hr at 24°C with DAP supplementation. The lowest concentration of ethanol 3.89 % was obtained after fermenting the sample with 71B yeast strain for 24 hr at 24°C without any nutritional supplement. Compared to no nutritional supplement, addition of DAP significantly increased the amount of ethanol, whereas addition of lupin flour decreased the amount of ethanol produced. The overall amount of ethanol produced was not dependent on the quantity of inoculation. However the rate of ethanol production in the first 48 h was normally faster with 2g inoculation for both yeast strains. For the fermentation performed with no nutritional supplement or DAP yielded 8-10% ethanol within 2-3 days. Analysis of the aroma compounds was performed using a DVB/CAR/PDMS SPME fibre and measured by GC-MS. Acetic acid was the predominant aroma compound found in the honey mead samples other than ethanol.

Date of Award	2020
Original language	English