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Ming-Wei S. Kao, Jeffrey K. Brecht, Jeffrey G. Williamson and Donald J. Huber

= melting flesh; NMF = non-melting flesh. Fig. 2. Respiration rate of MF ‘Flordaprince’ ( A–B ), MF ‘TropicBeauty’ ( C–D ), NMF ‘UFSun’ ( E–F ), and NMF ‘Gulfking’ ( G–H ) during 5 d of storage at 20 °C in 2008 and 2009. (Note: To obtain mg·kg −1 ·h −1

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C.R. Van Der Heyden, P. Holford and G.D. Richards

A freestone, nonmelting flesh peach would offer the opportunity to transport freestone peaches to distant markets, and so open lucrative export opportunities. Peach [Prunus persica (L.) Batsch.] germplasm segregating for semi-freestone and clingstone has been identified among the nonmelting flesh, open-pollinated progeny of the Univ. of Florida selection, Fla. 9-20C. The segregation approached a 1 : 1 ratio. No significant differences were detected between the two categories for titratable acidity, soluble solids concentration, or skin color. However, the semi-freestone progeny had significantly softer flesh than their clingstone siblings, although not soft enough to justify reclassification of the flesh texture. No simple genetic model can be proposed for the inheritance of this new phenotype. The semi-freestone, nonmelting germplasm represents a step towards a less perishable, freestone cultivar for the fresh market, as well as an opportunity to study the reason for the rarity of the freestone/nonmelting phenotype among peaches.

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David H. Byrne and Natalie Anderson

, clingstone peach with nonmelting flesh. It is from a cross between the California peach cultivar Crimson Lady and the Brazilian nonmelting cultivar Agata. ‘Crimson Lady’ is a high-chill, early-ripening, nonmelting, yellow-fleshed, clingstone peach released by

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Gerard W. Krewer, Thomas G. Beckman, Jose X. Chaparro and Wayne B. Sherman

produce an attractive, sweet-tasting, yellow, and nonmelting flesh fruit intended for the fresh fruit market. It is expected to produce fruit with tree-ripened taste while retaining firmness for longer shelf life than fruit from conventional melting flesh

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J.K. Brecht, K. Cordasco and W.B. Sherman

Two nonmelting flesh (`GUFprince' and `UF2000') and two melting flesh (`Tropic Beauty' and `Rayon') peach cultivars were segregated into ripeness categories at harvest according to initial flesh firmness and prepared as fresh-cut slices as described in Gorny et al. (HortScience 33:110–113), except that there were no “overripe” (0-13 N flesh firmness) stage nonmelting flesh fruit. Slices were stored at 1, 5, or 10 °C for 8 days and were evaluated for visual and taste quality, flesh firmness and color, and respiration and ethylene production rates every other day during storage. The optimal ripeness for preparing fresh-cut slices from the melting flesh cultivars was the “ripe” (13-27 N flesh firmness) stage; less-ripe melting flesh slices did not ripen at 1 or 5 °C and riper melting flesh slices and those held at 10 °C softened excessively, became discolored, and decayed. The optimal ripeness stage for the nonmelting flesh cultivars was 40-53 N flesh firmness, which corresponded to physiologically ripe (climacteric rise) for nonmelting flesh fruit, but melting flesh fruit at that firmenss were physiologically only mature-green (preclimacteric). Storage of nonmelting flesh slices was limited by surface desiccation at 1 °C, and by flesh discoloration at 5 and 10 °C, which was more severe in riper slices. The best storage temperature for both fruit genotypes was 1 °C, which prevented discoloration and decay over the 8-day storage period. Nonmelting flesh peach cultivars are better suited for fresh-cut processing than melting flesh cultivars because their firmer texture allows the use of riper fruit with better flavor than the less ripe fruit that must be used for fresh-cut melting flesh peaches.

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Ernesto A. Brovelli, Jeffrey K. Brecht, Wayne B. Sherman and Charles A. Sims

The notion that ethylene production levels in nonmelting-flesh (NMF) peach (Prunus persica L.) fruit are normally lower than those in melting-flesh (MF) fruit is refuted in our study. In fact, NMF fruit (`Oro A' and FL 86-28C) usually produced higher levels of ethylene than did MF fruit (FL 90-20 and `TropicBeauty'). In both MF and NMF peaches, the rate of ethylene production, rather than the respiration rate, provided a good indication of the developmental stage of the fruit at harvest. Ethylene content in fruit on the tree followed a climacteric pattern, with the level in `Oro A' (NMF) and FL 90-20 (MF) peaking at 50 and 12 μL·L–1, respectively. The respiratory climacteric was not apparent in either `Oro A' or FL 90-20, and levels of CO2 were similar in both genotypes.

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Yasar Karakurt, Donald J. Huber and Wayne B. Sherman

Some nonmelting flesh (NMF) peaches develop a characteristic off-flavor during postharvest ripening. A study was conducted using NMF genotypes from the Univ. of Florida breeding program to investigate the off-flavor development in melting flesh (MF) and NMF peach genotypes and to determine the compositional changes associated with the development of off-flavor during postharvest ripening at 8 °C. The study revealed that there were certain chemical components that were consistently associated with the occurrence of off-flavor. Generally, there was a significant increase in total soluble phenolics, polyphenoloxidase (PPO) activity and ethanol content with the increase in the percentage of off-flavored fruit with time in storage at 8 °C in NMF genotypes examined. However, total sugars and total soluble solids decreased significantly during the storage period. These changes in chemical composition of NMF genotypes were not observed in MF genotypes, which did not show off-flavor development. Moreover, highly significant linear correlations were detected between off-flavor development and soluble phenolics, PPO activity, ethanol content, total soluble solids, and sugars in Fla. 92-21C and USDA 87P285, which had the highest percentage of off-flavored fruit. Specifically, soluble phenolics, chlorogenic acid, PPO activity, and ethanol were positively correlated, but soluble sugars and soluble solids were negatively correlated with the off-flavor development. Thus, it is suggested that the accumulation of soluble phenolic compounds and ethanol, and the reduction of soluble solids and sugars contribute to the of off-flavor in NMF genotypes.

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Ernesto A. Brovelli, Jeffrey K. Brecht, Wayne B. Sherman and Charles A. Sims

A study to compare the response to postharvest chilling (4 °C) for up to 3 weeks of melting-flesh (MF)—FL 90-20, FL 90-21W, and FL 91-16—and nonmelting-flesh (NMF)—`Oro A', FL 90-35C, and FL 90-47C—peach (Prunus persica L.) genotypes revealed that MF fruit were notably more susceptible to the development of mealiness than NMF types. Cell separation in mealy fruit was demonstrated by the release of mesocarp cells to an aqueous medium, allowing determination of mealiness severity. At a histological level, chilling brought about an impressive expansion of the intercellular spaces in MF mesocarp tissue but did not affect NMF fruit. A decrease in flesh electrical resistance after 1 week of chilling was observed only in MF fruit. However, electrical resistance increased in MF and NMF fruit following 2 and 3 weeks at 4 °C. Electrical resistance also decreased with ripening of MF fruit but did not change when NMF fruit were ripened. Unlike NMF fruit, the MF genotypes FL 90-21W and FL 91-16 showed an increase in respiration rate due to chilling. The rate of ethylene production decreased after 1 week at 4 °C in MF and NMF genotypes. However, two MF and two NMF genotypes exhibited rising ethylene levels after the second week of storage at 4 °C, while ethylene production in one MF and one NMF genotype continued to decline.

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Ernesto A. Brovelli, Jeffrey K. Brecht, Wayne B. Sherman and Jay M. Harrison

Potential maturity indices were determined for two melting-flesh (FL 90-20 and Tropic Beauty) and two nonmelting-flesh (Oro A and Fl 86-28 C) peach cultivars. A range of developmental stages was obtained by conducting two harvests and separating fruit based on their diameter. Fruit in each category were divided into two groups. One group was used for determining potential maturity indices: soluble solids, titratable acidity, soluble solids: titratable acidity, peel and flesh color on the cheeks (CH) and blossom end (BE), CH and BE texture, ethylene production, and respiration rate. The other group was stored at 0°C for 1 week and ripened at 20°C for 2 days to simulate actual handling conditions, and were presented to a trained sensory panel, which rated the fruit for three textural (hardness, rubberiness, and juiciness) and three flavor aspects (sweetness; sourness; bitterness; and green, peachy, and overripe character). Principal component (PC) analysis was used to consolidate the results of the descriptive sensory evaluation into a single variable that could be correlated with the objective measurements at harvest. The first overall PC explained 40% of the total variation. Following are the attributes that best correlated with PC 1 and, thus, are promising maturity indices: for FL 90-20, peel hue, peel L, and CH texture; for Tropic Beauty, peel L, CH texture, and BE texture; for Oro A, CH texture, BE texture, and CH chroma; for 86-28C, BE texture, CH hue, and CH texture.

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Ernesto A. Brovelli, Jeffrey K. Brecht, Wayne B. Sherman and Charles A. Sims

Potential maturity indices were determined for two melting-flesh (FL 90-20 and `TropicBeauty') and two nonmelting-flesh (`Oro A'and Fl 86-28C) peach [Prunus persica (L.) Batsch.] genotypes. A range of developmental stages was obtained by conducting two harvests and separating the fruit based on diameter. Fruit in each category were divided into two groups. One group was used to determine potential maturity indices: soluble solids, titratable acidity, soluble solids to titratable acidity ratio, peel and flesh color on the cheeks and blossom end, cheek and blossom-end firmness, ethylene production, and respiration rate. The other group was stored at 0 °C for 1 week and ripened at 20 °C for 2 days to simulate handling conditions and presented to a trained sensory panel, which rated the fruit for three textural aspects (hardness, rubberiness, and juiciness) and six flavor aspects (sweetness, sourness, bitterness, and green, peachy, and overripe character). Principal component (PC) analysis was used to consolidate the results of the descriptive sensory evaluation into a single variable that could be correlated with the objective measurements at harvest. The attributes that best correlated with the first sensory PC of each genotype, and thus are promising maturity indices, were as follows: for FL 90-20, peel hue, peel L, and cheek firmness; for `TropicBeauty', peel L, cheek firmness, and blossom-end firmness; for `Oro A', cheek firmness, blossom-end firmness, and cheek chroma; and for 86-28C, blossom-end firmness, cheek hue, and cheek firmness.