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Eckhard Grimm, Stefanie Peschel, and Moritz Knoche

, 1939 ). The change in color is related to the degradation of chlorophyll, the presence of carotenoids in chromoplasts, and the accumulation of anthocyanins in the vacuoles ( Serrano et al., 2005 ). Recent investigations demonstrate that the exocarp is

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Holger Weichert, Stefanie Peschel, Moritz Knoche, and Dieter Neumann

aqueous continuum across the sweet cherry fruit exocarp that is referred to as the polar pathway ( Weichert and Knoche, 2006a ). Polar pathways are formed by hydration and orientation of polar functional groups in the cuticular membrane [CM ( Beyer et al

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Brent Tisserat and Paul D. Galletta

Some cultivars of mandarin (Citrus reticulata Blanco), sweet orange [Citrus sinensis (L.) Osb.], and trifoliate orange [Poncirus trifoliata (L.) Raf.] were found to have adventitious juice vesicles originating from their exocarp (peel). Several hundred green vesicles may be initiated from curvilinear stylar peel depressions of immature fruit. These vesicles develop similarly to juice vesicles from the endocarp except that, as the fruit matures, exocarp adventitious vesicles die prematurely and degenerate into a fruit surface blemish. Evidence suggests that juice vesicles and oil glands are homologous and merit reconsideration in ontological studies.

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Allan B. Woolf

`Hass' avocado (Persea americana Mill.) fruit were heat treated in water at 38 °C for 0 to 120 minutes, and stored at 0.5 °C for up to 28 days. After storage, fruit were ripened at 20 °C and their quality evaluated. External chilling injury (CI) developed during storage in nonheated fruit. Skin (exocarp) sectioning showed that browning developed from the base of the exocarp, and with longer storage, this browning moved outwards toward the epidermis. Longer durations of hot water treatment (HWT) progressively reduced CI; 60 minutes was the optimal duration that eliminated external CI, while best maintaining fruit quality. Concomitantly, electrolyte leakage of heated skin tissue increased ≈70% during storage, whereas electrolyte leakage of nonheated skin tissue increased ≈480% over the same period. Thus, significant protection was conferred by HWTs against low temperature damage to avocados and these effects are reflected in the morphology and physiology of the skin tissue.

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W. Robert Trentham, Carl E. Sams, and William S. Conway

). The PAS reaction was used as reported for tomato ( Solanum lycopersicum L.) exocarp ( Graham, 1997 ). Ultimately, a novel mixture of three dyes [Bismarck brown Y (certified dye #AcN-9), alcian blue 8GX (certified dye #ScAn-12), safranin O (certified

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Moritz Knoche, Eckhard Grimm, and Henrik Jürgen Schlegel

. The number of replications was 10. To relate to the and the water potential of the fruit ), a radial block of tissue (cross-section ≈2 × 2 mm, length ≈11 mm) extending from pit (endocarp) to skin (exocarp) was excised from the same batch of fruit

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Eckhard Grimm and Moritz Knoche

The skin is the primary load-bearing structure in a sweet cherry fruit (Prunus avium L.). Failure of the skin in rain cracking is considered to be related to water uptake. Little is known of the skin’s water potential, its osmotic potential (ΨΠ S), and turgor. The objective here was to quantify ΨΠ S relative to the osmotic potential of the flesh (ΨΠ F). Spatial resolution was achieved by monitoring plasmolysis in epidermal cells in tissue sections, incubated in selected osmotica using a light microscope method. Decreasing the osmotic potential [ΨΠ (more negative)] of the incubation medium increased the proportion (percent) of plasmolyzed epidermal cells. The pattern of increasing plasmolysis was sigmoidal with increasing osmolyte concentration. The value of ΨΠ for 50% of cells plasmolyzed, depended to some extent on the osmolyte used. The value of ΨΠ became slightly less negative for the osmolytes tested in the order: 1) mannitol, 2) sucrose, and 3) artificial cherry juice (a solution comprising the five major osmolytes of sweet cherry juice in the appropriate proportions and concentrations). There was little difference in the value of ΨΠ at 50% plasmolysis between the cultivars Hedelfinger, Sam, and Sweetheart. In all three cultivars, the value of ΨΠ F (measured for expressed juice using an osmometer) was markedly more negative than that of ΨΠ S (measured for 50% plasmolysis). Incubating skin segments in juice from the same fruit resulted in the plasmolysis of most (85.7% to 96.4%) of the epidermal cells. As fruit development progressed from stage II [27 day after full bloom (DAFB)] to the fully mature stage III (97 DAFB), plasmolysis occurred for increasingly more negative values of ΨΠ. Moreover, the difference between the osmotic potential values recorded for the flesh ΨΠ F and for the skin ΨΠ S increased. Plasmolysis of epidermal cells was accompanied by a marked swelling of their walls. The results indicate a marked difference in the osmotic potential of flesh (ΨΠ F trended more negative) and skin cells (ΨΠ S trended less negative).

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Eckhard Grimm, Stefanie Peschel, Tobias Becker, and Moritz Knoche

observations in vineyards ( Considine, 1982 ). Although sweet cherries differ somewhat in structure and texture from grape berries, this model may in principle also be applied to sweet cherries ( Considine and Brown, 1981 ). Here, the strained exocarp holds the

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Charles S. Krasnow and Mary K. Hausbeck

conducted twice. Fruit firmness testing and wound assay. Pericarp and exocarp firmness of healthy fruits were measured using a fruit penetrometer (model FT 327; QA Supplies LLC, Norfolk, VA) with a 5-mm-diameter press. The measurement was taken from squash

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Maite A. Chauvin, Matthew Whiting, and Carolyn F. Ross

harvested past optimum maturity due to an insufficient labor force. Optimum commercial maturity of sweet cherry fruit is generally determined by red coloration of fruit exocarp, with a dark red/mahogany thought of as ideal for the industry standard cultivar