Abstract

In an attempt to improve the processing of dried ginger (Zingiber officinale), the effect of drying and size on the proximate, mineral and volatile oil contents were investigated.  Fresh gingers were cleaned and divided into two halves, one part was sliced and the other grated. Each of the sliced and grated ginger was divided into two; each half was subjected to sun and oven drying at 50°C. The samples were milled separately using plate mill and sieved with sieve number 20. The sieved samples were subjected to proximate, mineral and volatile oil content analyses. The result of the proximate compositions showed a significant difference (at 5% level of significant) between fresh samples and all dried samples, and between sun dried and oven dried samples. Magnesium and calcium contents of dried samples ranged between 120 and 162 mg/100 g, and 380 mg/100 g, respectively. The least available minerals are iron (0.05-2.04 mg) and zinc (0.46-0.92 mg). The volatile oil content of the samples are 0.17, 0.69, 1.36, 0.81 and 0.41% for fresh, grated oven dried (GOD), sliced oven dried (SOD), sliced sun dried ginger (SSD) and grated sun dried (GSD), respectively. Sliced oven dried sample was found best among all the samples because it retained the highest volatile oil, protein, calcium, and magnesium.  Slicing and oven drying at 50°C was therefore recommended.

Key words: Ginger, slicing, grating, drying, volatile oil.