Investigation of essential oils as natural preservatives for juice and jam

This study was carried out to investigate the performance of lemongrass essential oil (LEO) and cinnamon essential oil (CEO) as alternative preservatives for pineapple juice and jam. The essential oils (EOs) were produced by hydro-steam distillation of either fresh lemongrasses or fresh cinnamon leaves using a Clevenger apparatus. Pineapple jam samples were produced using lemon peel extract as a source of pectin and lemon juice as a source of acid. Pasteurized and unpasteurized pineapple juice samples were also prepared. The samples were dosed with either LEO or CEO at concentrations of 500 and 1000 ppm while others were dosed with 250 and 500 ppm of each essential oil. The samples were stored either at room temperature or at refrigeration temperature. Analysis of samples for changes in total bacterial counts (TPC), total fungal counts (TFC), vitamin C, flavour, colour, total quality, sugar concentration and pH was done after every 4 days within a period of 24 days for juice and after every 10 days within a period of 60 days for jam. Vitamin C content was determined using the 2,6 dichlorophenol indophenol visual titration method whereas sensory analysis was done by a team of end users. Statistical analysis of data on sensory and physico-chemical properties was done using STATIGRAPHICS Centurion software. The findings revealed that both LEO and CEO slowed down the deterioration of pineapple juice and jam, the rate of microbial growth, loss of vitamin C, and changes in flavour, colour and total quality during storage of both products, while stabilizing sugar concentration and pH of juice. Improved preservation effect was more pronounced for refrigerated samples and pasteurized juice samples. The inhibitory effect on microbial growth was proportional to the concentration of EO