A comparison study of the nutritional, mineral and volatile compositions of three dry forms of ginger rhizomes, and antioxidant properties of their ethanolic and aqueous extracts

Objective:To compare the most accessible dry forms of ginger rhizomes (Zingiber officinale) used as a spice and as a remedy in order to choose the best ginger for medicinal purpose. Methods:Freshly air dried ginger, commercially dry rhizomes and ginger available in powder form are investigated in terms of nutritional values (proximate and mineral compositions) and volatiles profile. Ethanolic and aqueous extracts (decoctions and infusions) were prepared for total phenolic, flavonoid and tannin contents determination. Also, three standard tests were established in order to estimate the best extract with the better antioxidant potential. Results:The results showed unlike proximate composition revealing different nutritional values. In fact, freshly dried ginger contained much ash, while already dry samples contained much protein. In addition, mineral contents of studied samples indicated their dissimilar richness especially in Ca, Mg, Na, K, Cu, Fe, and Mn. Solid phase micro-extraction gave volatile profiles with many interesting compounds, only 26 from the 51 identified components were common to studied samples with bioactive compounds predominance in freshly dried sample. Also, the antioxidant potential established by three different tests was higher in already dry samples and was positively correlated with their higher contents in the determined phytochemicals. The ethanolic extracts showed higher antioxidant activities than aqueous extracts. Decoctions and infusions were almost similar proving that long cooking time did not affect ginger antioxidant potential. Conclusions:This work highlighted the benefits of traditional preparations of ginger as sources of bioactive compounds, namely antioxidants, and proved that the available commercial samples are not identical and encouraged analyzing samples before uses depending on needs.

Antioxidant activity, volatile and nonvolatile composition of twoPhoenix dactylifera L. by-products

Objective:To examine the nonvolatile components of the date pulp and seeds of two minor Tunisian date palm cultivars Arechti and Korkobbi at besser stage and to investigate their antioxidant activity, their phytochemical compounds and their aromatic volatiles composition. Methods:The physico-chemical properties, the aroma composition, the mineral profile, the phytochemical content and thein vitro antioxidant activity of those two common date palm fruit varieties and those of their seeds were evaluated. All measurements were made at the besser stage, which showed the highest amount of secondary metabolites. Results:New volatiles compounds are detected in both flesh and seeds and the results revealed that those by products are a suitable source of mineral content and have a high potential of natural antioxidants and good antiradical capacities. Conclusions: Thanks to their characteristics, they could potentially be considered as a cheap resource for new functional food ingredient and novel pharmaceutical applications.