The effect of vinegar and drying (Solar and Open Sun) on the microbiological quality of ginger (ZINGIBER OFFICINALE ROSCOE) rhizomes

This study evaluated the influence of 10% vinegar and solar drying using two solar dryers and open-sun drying on the microbiological quality of ginger (Zingiber officinale Roscoe) rhizome. The rhizomes were analyzed for bacterial, mold, and Salmonella populations in the raw state, which were water-washed and soaked in 10% vinegar, and in dried form. The fungal population was isolated and identified. Fresh and dried ginger rhizome contained both bacterial and fungal population in the range of 3.0 x 102 ± 1.14 x 102 to 2,180 x 109 ± 70.7 x 109 CFU/g. The stainless steel solar dryer had fewer fungal loads among the drying methods. Aspergillus and Penicillium species of mycotoxin-producing potential were identified. The 10% vinegar as pretreatment showed no significant difference (p ≤ .05) in the bacterial population reduction but in the fungal population reduction. Growth of fungi in fresh and dried ginger extracts was lower compared with growth in Potato Dextrose Broth.

Simultaneous Determination of 6-Shogaol and 6-Gingerol in Various Ginger (Zingiber officinale Roscoe) Extracts and Commercial Formulations Using a Green RP-HPTLC-Densitometry Method

Various analytical methodologies have been reported for the determination of 6-shogaol (6-SHO) and 6-gingerol (6-GIN) in ginger extracts and commercial formulations. However, green analytical methods for the determination of 6-SHO and 6-GIN, either alone or in combination, have not yet been reported in literature. Hence, the present study was aimed to develop a rapid, simple, and cheaper green reversed phase high-performance thin-layer chromatography (RP-HPTLC) densitometry method for the simultaneous determination of 6-SHO and 6-GIN in the traditional and ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas. The simultaneous analysis of 6-SHO and 6-GIN was carried out via RP-18 silica gel 60 F254S HPTLC plates. The mixture of green solvents, i.e., ethanol:water (6.5:3.5 v/v) was utilized as a mobile phase for the simultaneous analysis of 6-SHO and 6-GIN. The analysis of 6-SHO and 6-GIN was performed at λmax = 200 nm for 6-SHO and 6-GIN. The densitograms of 6-SHO and 6-GIN from traditional and ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were verified by obtaining their single band at Rf = 0.36 ± 0.01 for 6-SHO and Rf = 0.53 ± 0.01 for 6-GIN, compared to standard 6-SHO and 6-GIN. The green RP-HPTLC method was found to be linear, in the range of 100-700 ng/band with R2 = 0.9988 for 6-SHO and 50-600 ng/band with R2 = 0.9995 for 6-GIN. In addition, the method was recorded as "accurate, precise, robust and sensitive" for the simultaneous quantification of 6-SHO and 6-GIN in traditional and ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas. The amount of 6-SHO in traditional extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas was obtained as 12.1, 17.9, 10.5, and 9.6 mg/g of extract, respectively. However, the amount of 6-SHO in ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were obtained as 14.6, 19.7, 11.6, and 10.7 mg/g of extract, respectively. The amount of 6-GIN in traditional extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were found as 10.2, 15.1, 7.3, and 6.9 mg/g of extract, respectively. However, the amount of 6-GIN in ultrasonication-assisted extracts of ginger rhizome, commercial ginger powder, commercial capsules, and commercial ginger teas were obtained as 12.7, 17.8, 8.8, and 7.9 mg/g of extract, respectively. Overall, the results of this study indicated that the proposed analytical technique could be effectively used for the simultaneous quantification of 6-SHO and 6-GIN in a wide range of plant extracts and commercial formulations.

Improvement of 6-gingerol production in ginger rhizomes (Zingiber officinale Roscoe) plants by mutation breeding using gamma irradiation

Ginger (Zingiber officinale Roscoe) is a valuable culinary and medicinal plant. The compound 6-gingerol is the main gingerol in ginger rhizomes and it possesses interesting pharmacological and physiological properties. Mutation breeding involved using low doses of gamma radiation (5-30 Gy) to increase the genetic variability in ginger rhizomes (M1 generation). Ginger plants selected from the next generation (M2) were characterized and subjected to quantitative analysis for 6-gingerol content using HPLC of ginger extracts. M2 offspring from a parent ginger rhizome irradiated with 20 Gy was found to have a high 6-gingerol content (38.4 ± 0.01 mg/g methanol extract in comparison to 22.1 ± 0.03 mg/g methanol extract in non-irradiated control samples). Radiation induced genetic variability was also probed and confirmed using RAPD-PCR analysis. This research demonstrates the potential for ginger improvement and to our knowledge is the first to report the use of gamma radiation in breeding ginger plants with enhanced 6-gingerol content.

Rapid ultrasonic and microwave-assisted micellar extraction of zingiberone, shogaol and gingerols from gingers using biosurfactants

Two kinds of extraction methods ultrasonic-assisted micellar extraction (UAME) and microwave-assisted micellar extraction (MAME) coupled with ultra-high performance liquid chromatography with ultraviolet detector (UHPLC-UV) were developed and evaluated for extraction and determination of zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol in Rhizoma Zingiberis and Rhizoma Zingiberis Preparata. A biosurfactant, hyodeoxycholic acid sodium salt, was used in micellar extraction. Several experimental parameters were studied separately by a univariate method. The result indicated that the MAME was more efficient than UAME. The optimal conditions of MAME were as follows: 100mM of hyodeoxycholic acid sodium salt was used as surfactant, the irradiation time was set at 10s and the extraction temperature was set at 60°C. The validation results indicated that the limits of detection were in the range of 3.80-8.11ng/mL. The average recoveries were in the range of 87.32-103.12% for the two samples at two spiking levels. Compared with other reported methods, the proposed MAME-UHPLC-UV method was more effective, quicker (10s) and more eco-friendly.