The Effect of Ginger Extract on the Acceptability and Storability of a Non-alcoholic Beverage (Sorghum Stem Sheath Drink) in Nigeria

Aims: This study investigated the acceptability and preservative influence of ginger extract on sorghum stem sheath drink.
Study Design: Factorial design was used for this study.
Place and Duration of Study: This study was carried out in the Food Processing, Sensory and Microbiology Laboratories in the Department of Food Science and Technology, Federal University of Technology, Akure, Ondo State between September 2010 and December, 2010.
Methodology: The sorghum stem sheath was dry cleaned, pulverized and packed in air tight containers until utilized. The stem sheath flour was soaked, boiled and filtered. The filtrate was sweetened with food grade sucrose to a brix level of 10° before dispensing into previously sterilized bottles and pasteurized at 75°C for 30 mins. The dry crude extract of Zingiber officinale was weighed differently and prepared with distilled water at 0.5%, 1.0%, 1.5%, 2.0% and 2.5% concentrations. The drink was treated respectively with different concentrations. Changes in quality of ginger (Zingiber officinale) spiced poporo during accelerated storage at 50°C were evaluated for 4 weeks.
Results: The sensory evaluation revealed over 80% preference for the 0.5% ginger extract inclusion by the panelists. The microbiological analysis showed that Coliform and total viable bacteria were found to be completely absent in the pasteurized samples. Bacteria was also absent in spiced samples stored for 2 weeks (14 days). The microbial load increased from 4-8 x102 cfu/ml to 7-15 x102 cfu/ml in the spiced beverage from week 3 to 4, depending on the concentration of the spice, whereas the control sample showed considerable bacteria growth (2-20 x 102 cfu/ml) from week 1 to week 4 but both spiced and control samples showed no Coliform growth throughout the storage period. The pH in the control and spiced samples decreased gradually from 7.00-5.20 while the titratable acidity increased from 0.040-0.076% lactic acid with increase in ginger concentrations from 0.5 to 2.5% in the spiced samples. Decrease in vitamin C from 232.64-138.60 mg/100ml throughout the storage period followed similar trends.
Conclusion: The anti-microbial activity of the spice was established with the microbial profile of the spiced beverages during storage at an elevated temperature of 50°C in which the total viable bacteria count was absent for two weeks (14days) and Coliform bacteria was completely absent in all samples throughout storage period. The result of this study reveals that nutritious and relatively shelf stable non- alcoholic beverage could be produced from sorghum stem sheath and local spices without the use of chemical preservatives.