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Advances in Postharvest Fruit and Vegetable Technology, 2015, p.258-281
Ort / Verlag
United Kingdom: CRC Press
Erscheinungsjahr
2015
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Oxygen (O2) is the most abundant molecule in the biological system and is often a
source of free radicals as its partially reduced species are generated through normal
metabolic processes. Most of the O2 consumed by nonphotosynthetic plant tissues
is reduced to water by the terminal oxidase(s) of the respiratory electron transport
chain in the mitochondria (Apel and Hirt, 2004). Reactive oxygen species (ROS)
are the partially reduced forms of molecular oxygen that result from either the excitation of O2 to form singlet oxygen or the transfer of one, two, or three electrons to
O2 to form, respectively, superoxide (O2−), hydrogen peroxide (H2O2) or hydroxyl
radical (OH·) (Hodges et al., 2004). Both O2− and OH· are extremely reactive and
can cause oxidative injury leading to cell death. The average life span of these ROS
varies from nanoseconds (e.g., OH) to milliseconds (e.g., O2−, H2O2). The OH· can
also be generated by the interaction of O2− and H2O2 in the presence of transition
metal ions, so called “Haber-Weiss reaction.” Cells do not possess detoxication
mechanism for OH· due to its very high reactivity, and rely on mechanisms preventing its formation. These mechanisms include the preceding elimination of O2− and11.1 Introduction ... 237
11.2 Mechanisms for ROS Scavenging ... 23811.2.1 Enzymatic Antioxidants ... 239
11.2.2 Nonenzymatic Antioxidants ... 23911.3 Postharvest Oxidative Stress... 241
11.4 Factors Affecting Postharvest Oxidative Stress ... 24311.4.1 Genotype/Cultivar ... 243
11.4.2 Harvest Maturity ...244
11.4.3 Storage Temperature and Duration ...246
11.4.4 Storage Atmospheres ...248
11.4.5 Postharvest Treatments ... 25211.4.5.1 1-Methylcyclopropene ... 252
11.4.5.2 Nitric Oxide ... 25311.5 Conclusions ...254
References ... 255H2O2 and/or sequestering metal ions that catalyze the Haber-Weiss reaction with
metal-binding proteins such as ferritins or metallothioneins (Gechev et al., 2006).
In addition to H2O2, O2− can also react with nitric oxide radical (NO·) to form peroxynitrite (ONOO−), which can rapidly protonate to peroxynitrous acid (ONOOH),
a powerful oxidizing agent. The reactions among various types of ROS can, therefore, generate intermediates or products that are capable of causing extreme levels
of oxidative injury to the cell.