Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
Department of Food Science and Technology, Tehran North Branch, Islamic Azad University, Tehran 1987973133, Iran.
Molecules. 2018 Jul 5;23(7):1646. doi: 10.3390/molecules23071646.
Gingerols and shogaols are compounds found in ginger ( Roscoe); shogaols are found in lower concentration than gingerols but exhibit higher biological activities. This work studied the effects of different drying methods including open sun drying (OSD) solar tunnel drying (STD) and hot air drying (HAD) with various temperature on the formation of six main active compounds in ginger rhizomes, namely 6-, 8-, and 10-gingerols and 6-, 8-, and 10-shogaols, as well as essential oil content. Antioxidant and antimicrobial activity of dried ginger was also evaluated. High performance liquid chromatography (HPLC) analysis showed that after HAD with variable temperature (120, 150 and 180 °C), contents of 6-, 8-, and 10-gingerols decreased, while contents of 6-, 8-, and 10-shogaol increased. High formation of 6-, 8-, and 10-shogaol contents were observed in HAD (at 150 °C for 6 h) followed by STD and OSD, respectively. OSD exhibited high content of essential oil followed by STD and HAD method. Ginger-treated with HAD exhibited the highest DPPH (IC of 57.8 mg/g DW) and FRAP (493.8 µM of Fe(II)/g DM) activity, compared to STD and OSD method. HAD ginger exhibited potent antimicrobial activity with lower minimum inhibition concentration (MIC) value against bacteria strains followed by STD and OSD, respectively. Ginger extracts showed more potent antimicrobial activity against Gram positive bacteria than Gram negative bacteria strains. Result of this study confirmed that conversion of gingerols to shogaols was significantly affected by different drying temperature and time. HAD at 150 °C for 6 h, provides a method for enhancing shogaols content in ginger rhizomes with improving antioxidant and antimicrobial activities.
姜烯酚和姜酮酚是生姜（Roscoe）中的化合物；姜酮酚的浓度低于姜烯酚，但具有更高的生物活性。本工作研究了不同干燥方法（包括露天晒干（OSD）、太阳能隧道干燥（STD）和热空气干燥（HAD））对生姜根茎中六种主要活性化合物（即 6-、8-和 10-姜烯酚和 6-、8-和 10-姜酮酚）以及精油含量形成的影响。还评估了干生姜的抗氧化和抗菌活性。高效液相色谱（HPLC）分析表明，经过不同温度（120、150 和 180°C）的 HAD 处理后，6-、8-和 10-姜烯酚的含量降低，而 6-、8-和 10-姜酮酚的含量增加。HAD（在 150°C 下处理 6 小时）后观察到 6-、8-和 10-姜酮酚含量的高形成，其次是 STD 和 OSD。OSD 表现出较高的精油含量，其次是 STD 和 HAD 方法。与 STD 和 OSD 方法相比，HAD 处理的生姜表现出最高的 DPPH（IC50 为 57.8mg/g DW）和 FRAP（493.8µM 的 Fe(II)/g DM）活性。HAD 生姜对细菌菌株的最低抑菌浓度（MIC）值较低，表现出最强的抗菌活性，其次是 STD 和 OSD。生姜提取物对革兰氏阳性菌的抗菌活性强于革兰氏阴性菌。本研究结果证实，不同的干燥温度和时间对姜烯酚向姜酮酚的转化有显著影响。在 150°C 下处理 6 小时的 HAD 为提高生姜根茎中姜酮酚的含量，提高抗氧化和抗菌活性提供了一种方法。
