were 31.1 and 20% against 14.8 and 11.2%, respectively, when compared with foreign extracts (Kostrzewa and Karwaswska, 1976).

Pungent constituents of ginger, separated as TMS derivatives, were reported by Harvey (1981). Five gingerols (n = 2, 4, 6, 8, 10), three methylgingerols (n = 4, 6, 8), four shogaols (n = 2, 4, 6, 8), two methylshogaols (n = 4, 8), paradol (1i), and three gingerdiones were identified. Also found in the low-temperature region of the chromato-gram were: ar-curcumene, several sesquiterpene hydrocarbons and their hydroxylated derivatives, zingerone and fatty acids (palmitic, oleic, and stearic).

Odoragram and aromagram of gingerol have been reported by Ney (1990a,b) using the sniffing method. As pepper, chilies, or mustard, they are characterized by a pungent taste. The content of oleoresins extracted with three different solvents has been studied by Taveira Magalhaes et al. (1997a,b) from various areas of Brazil. Results for the oleoresins and the essential oils are given in Table 3.12. The highest percentage of oleoresins was observed with ethanol as the solvent, whereas essential oils are better extracted with methylene chloride

Geographical variation of the content of gingerols was studied for different areas of India: Gujarat, Madhya Pradesh, Maharashtra, Kerala, and West Bengal (Sane et al., 1998). Analyses were carried out by HPLC using a Camag Limonat IV apparatus, benzene/methanol (10: 1 v/v) as the eluent, 310 nm scanning wavelength, and analysis of variance (ANOVA) calculations in order to determine whether the variation was significant or not. From these results, it can be concluded that there is no significant variation in the gingerol content in different states.

Comparison between the pungent compounds in ginger powder, ginger skin, and baked ginger was carried out by Huang et al. (1999). The content of gingerol in the three samples was 1.02, 0.28, and 0.25 g/100 g, respectively. Baked ginger contained 0.45 g/kg shogaols, but there were only traces in the other two samples. The stability of gingerols and shogaols in aqueous solution was studied by Bhattarai et al. (2001). Because gingerols are biologically active compounds, they may make a significant contribution toward medicinal applications of ginger and other products derived from ginger. They are thermally labile due to the presence of a (3-hydroxyl-keto group in the structure and undergo dehydration readily to form the corresponding shogaols, as previously shown. Their stability was studied in the temperature range of 33 to 100° C in aqueous solutions at pH 1.4 to 7.

A study of the degradation product (6)-shogaol, or (1-(4-hydroxy-3-methoxyphe-nyl)decan-4-ene-3-one), was carried out by HPLC. Kinetics of (6)-gingerol degradation was characterized by least-square fitting of a rate equation. Degradation rates were found to be pH dependent with greatest stability being observed at pH 4. The reversible degradation of (6)-gingerol at 100° C and pH 1 was relatively fast and reached equilib-

Table 3.12 Percentages of oleoresins and Brazilian essential oils with different solvents*


Oleoresins (%)

Essential oils (%)


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