Abstract: The flavedo peel extracts of unripe Shiikuwasha (Citrus depressa Hayata) fruits were extracted using steam distillation (SD) or a cold‐press (CP) system. Volatile aroma content and composition were determined using gas chromatography (GC) and each compound was identified using gas chromatography‐mass spectrophotometry (GC‐MS). The major constituents of the extracts were monoterpene hydrocarbons (91.75–93.75%[709.32–809.05 mg/100 g of fresh flavedo peel]) including limonene (43.08–45.13%[341.46–379.81 mg/100 g of fresh flavedo peel]), γ‐terpinene (27.88–29.06%[219.90–245.86 mg/100 g of fresh flavedo peel]), and p‐cymene (8.13–11.02%[61.47–97.22 mg/100 g of fresh flavedo peel]). The extraction process used was determined to be a decisive factor that affects the composition of key citrus aroma components, as well as the antioxidant activities of the Shiikuwasha fruit. Antioxidant capabilities of the extracts were examined by assay of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging activity and β‐carotene bleaching inhibition. The cold‐press extraction system may better retain the total phenolic content of the flavedo peel and display superior antioxidant activities, compared to the steam distillation extraction method.
Practical Application: Shiikuwasha (Citrus depressa Hayata) is a type of small citrus fruit, and has been used as raw material for beverage and food additive productions in Japan. It had a unique aroma composition in which the limonene content of its peels is lower than that of other commonly known citrus peels. The present study detailed the volatile aroma composition, as well as antioxidant capabilities of Shiikuwasha peel extracts of different extraction methods, that are cold‐press and steam distillation methods. The results of this study may provide a basis for selection of Shiikuwasha peel extracts in food industry for citrus flavor production.
The mechanism by which small molecules assemble into microscale tubular structures in aqueous solution remains poorly understood, particularly when the initial building blocks are non‐amphiphilic molecules and no surfactant is used. It is here shown how a subnanometric molecule ... more
The image illustrates a natural phenomenon of droplet formation caused by the condensation of vapor on a nonwettable surface at temperature below the dew point. Real‐time observing the light scattered from the droplets may lead to a new mechanism for vapor sensing. However, the dew point ... more
NO is a key vasodilator in mammalian cardiovascular systems and has been shown to sensitize tissue to γ‐radiation. However, photochemical NO precursors that can be activated by these NIR wavelengths are extremely limited. G. D. Stucky, D. Zhao, P. C. Ford, F. Zhang and co‐workers have ad ... more
A team of pioneering South Korean scientists have succeeded in producing the polymers used for everyday plastics through bioengineering, rather than through the use of fossil fuel based chemicals. This groundbreaking research, which may now allow for the production of environmentally consci ... more
In the past, restoration of paintings and other old artwork often involved application of acrylic resins to consolidate and protect them. One of the most important tasks for modern restorers is thus to remove these layers, because it turns out that acrylic resins not only drastically change ... more
Converting the trash that fills the world's landfills into biofuel may be the answer to both the growing energy crisis and to tackling carbon emissions, claim scientists in Singapore and Switzerland. New research published in Global Change Biology: Bioenergy, reveals how replacing gasoline ... more