Full Length Research Paper

Changes in the quality of zobo beverages produced from Hibiscus sabdarifa (Linn roscelle) and the effects of extract of ginger alone or in combination with refrigeration

Ogiehor I. S.¹*, Nwafor O. E.² and Owhe-Ureghe U. B.²

¹Department of Microbiology, Food and Industrial Division, Ambrose Alli University, P. M. B. 14, Ekpoma, Nigeria.

²Department of Microbiology, Food and Nutrition unit, Delta State University, P. M. B. 1, Abraka.

*Corresponding author. E-mail: biodec@yahoo.com.

Accepted 26 December, 2007

Quality changes in zobo beverage produced from Hibiscus sabdarifa during storage and the effects of extracts of ginger (Zingiber officinale) alone or in combination with refrigeration at 6^○C were evaluated for six (6) weeks duration. Results shows that the total viable bacterial count increased from 0.9 ± 0.01 log₁₀ cfu/ml to 8.42 ± 0.1 Log₁₀ cfu/ml at the 9^th day of storage and thereafter decrease steadily till the end of the storage period (21) days. While the total viable fungi count increased steadily from no growth after boiling and filtration to 6.14 ± 0.1 log₁₀ cfu/ml at the 14^th day of storage and thereafter decrease steadily till the end of the storage period. Treatment with 0.2% extract of ginger at ambient laboratory temperature (30.5 ± 2^○C) retarded the total viable bacterial and fungi count for 10 days with minimal growth from the 14^th day which increase sluggishly. However treatment with 0.2% extract of ginger and refrigeration at 6^○C further retarded the total viable bacteria and fungi count for 21 days with insignificant growth from the 28^th day which was not sustained. The pH decreased gradually from 5.10 ± 0.01 to 2.98 ± 0.00 while the titratable acidity (TA) increased from 0.021 to 0.060 during storage for 21 days. Slight changes were observed in samples treated with 0.2% extract of ginger whereas the pH and TA were fairly stable in samples treated with 0.2% extract of ginger refrigerated at 6^○C for 42 days. Gradual increase was recorded in the total soluble solids (TSS), vitamin C, protein and carbohydrate contents up to the 6^th and 9^th day of storage and thereafter decreased sharply till the end of the storage period for freshly prepared samples. However minimal changes were noted and recorded in samples treated with 0.2% extract of ginger all through the storage period. Whereas, sample treated with 0.2% extract of ginger and refrigerated at 6^○C were fairly stable for 42 days of storage. Overall sensory evaluation shows that acceptability was in the order 0.2% ginger extract + 6^○C > 0.2% extract of ginger > freshly prepared samples.

Key words: Zobo beverage, extract of ginger, refrigeration.