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B. D. Horton

Cultivars of fresh market peaches (Prunus persica, L. Batsch) vary in the duration for maximum yields in the shipping stage (firm ripe) from once-over harvests. A cultivar having many firm ripe fruit with few green and over ripe at a given time has a narrow maturity range. It can be picked fewer times, facilitate mechanical once-over harvests and reduce spray costs. Fruit were harvested from small trees or scaffold branches of large trees at 2- to 3-day intervals as once-over harvests on 4 dates to estimate maturity range and duration of the maximum firm ripe fruit. Fruit of 3 cultivars were graded by color into maturity stages: 1) green, 2) firm ripe, and 3) over ripe. `Loring' had 82% firm ripe sorted in the 1st 3 harvests in 1987 and 1988. `Redskin' had 83% firm ripe in the 2nd and 3rd harvests in 1987. `Redglobe' had 85% marketable in the 2nd and dropped to 75% in the 3rd harvest in 1987. `Redhaven' had about 80% firm ripe in the 1st 3 harvests in 1988. Results indicate that the duration of narrow maturity ranges of `Loring' and `Redhaven' would permit them to be harvested over about 5 days with high yieids in the firm-ripe stage.

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Dwight Wolfe and Gerald Brown

The maturity indices of percent fruit drop, percent soluble solids, and flesh firmness of apples from trees with `Starkspur Supreme' scions on nine rootstocks were compared over the five-year period 1985-1989. The nine rootstocks included EMLA 7, EMLA 9, EMLA 26, EMLA 27, Mark, MAC 24, Ottawa 3, OAR 1, and M9.

The five-year averages of each of the maturity indices varied significantly among the nine stions. The average percent fruit drop was more strongly correlated with trunk cross-sectional area (r=0.572) than it was with cumulative yield efficiency (r=0.346). Flesh firmness was significantly correlated with cumulative yield efficiency (r=0.398) but not with either trunk cross-sectional area or cumulative yield. The average percent soluble solids was more significantly correlated with trunk cross-sectional area (r=0.770) than it was with either cumulative yield efficiency (r=0.383) or cumulative yield (r=0.637). It is suggested that tree size may be used as an indicator for predicting maturity in cases where little or no information is available on the effects of that particular rootstock on maturity.

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Armida Rodriguez-Felix, Evelia Araiza-Lizarde, Monica A. Villegas-Ochoa, and Elsa Brineas-Taddei

Physico-chemical and physiological changes of `Flordaprince peach fruits harvested at different maturity stages were evaluated during low temperature storage. Harvested fruits were immediately classified into four different maturity stages based on red-skin color (I, 20%; II, 40%; III, 60%; and IV, 80%). Fruits were stored at 2 C (90% R.H.) for 0, 15, and 30 days. Following cold storage conditions, fruits were transferred to a 20 C room. Physico-chemical and physiological characteristics evaluated during storage included weight loss, firmness, pH, titratable acidity, skin color (hue), total soluble solids, respiration rate, and ethylene production. Weight loss increased (up to 40%) after 27 days storage at 2C. The fruits harvested at maturity stage I showed the lowest weight loss. Flesh firmness decreased significantly during storage at 2 C. Fruits from stages I and II had higher firmness than fruits harvested at stages III and IV. A significant change from green-yellow to red color was observed in fruits of the distinct maturity stages during storage at 20 C.

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Brandon M. Hurr, Donald J. Huber, and James H. Lee

In this study, ripening characteristics, including color change and softening, were determined for tomato (Lycopersicon esculentum `Florida 47') fruit at immature-green through light red stages of development and subsequently treated with 1 μL·L–1 1-methylcyclopropene (1-MCP). Special attention was directed at comparing the responses of immature and mature-green fruit. Surface color and whole fruit firmness were measured every other day. 1-MCP delayed or slowed color changes and softening in fruit of every maturity class, with differences between control and treated fruit evident immediately following 1-MCP application for 24 h at 20 °C. Fruit treated with 1-MCP at early maturity stages (immature-green, mature-green, and breaker) exhibited an extended delay in external red pigment accumulation compared with control fruit. Fruit of all maturity classes developed acceptable final hue values (hue angle ≤55°), and the time required to reach these values declined with advancing fruit maturity. Immature-green fruit treated with 1-MCP did not attain an acceptable degree of softening during the specified storage periods examined before deteriorating due to shriveling and pathogen proliferation. 1-MCP-treated mature-green and breaker stage fruit did recover to acceptable firmness (5–10 N) and hue values but exhibited a severely reduced storage life thereafter compared with untreated fruit of equal maturity. Fruit at turning and more advanced stages exhibited reduced rates of softening and color development when treated with 1-MCP, yet they attained firmness and color values within the range of acceptability for commercial use. Fruit treated with 1-MCP at pink and light-red stages of ripening developed normal external color and exhibited significantly extended postharvest life due largely to a significant retention in firmness when compared to control fruit. Based on the studies described for `Florida 47' tomato fruit, 1-MCP would appear to be of little benefit and possibly detrimental if applied to early maturity fruit, most notably greens and breakers, due to irreversible limitations in the capacity of these fruit to soften to acceptable values. In sharp contrast, more advanced stage fruit, particularly pink and light red, responded to 1-MCP with significantly extended shelf-life due to retention of firmness.

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James M. Wargo, Ian A. Merwin, and Christopher B. Watkins

`Jonagold' apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] often fail to develop adequate red coloration at maturity and become soft and greasy in storage. During two growing seasons, we tested factorial combinations of three preharvest treatments affecting `Jonagold' quality at harvest and after storage: 1) three nitrogen (N) treatments [36 kg·ha-1 soil applied N, 6.9 kg·ha-1 of urea-N (1% w/v) in foliar sprays mid-May and June, or no N fertilizers]; 2) trunk girdling in early August each year; and 3) foliar applications of aminoethoxyvinylglycine (AVG, formulated as ReTain) 3 weeks before the first scheduled harvest. Fruit were sampled at four weekly intervals each year and evaluated for maturity and quality at harvest and after storage. Foliar urea and soil-applied N delayed red color development in 1998 but not 1999, increased fruit size in girdled and nonAVG treated trees in both years, and increased greasiness in 1999 only. AVG reduced fruit greasiness after storage both years. Nitrogen uptake was reduced in the dry Summer 1999, but N treatments still increased poststorage flesh breakdown. Mid-summer trunk girdling increased red coloration and intensity both years and improved market-grade packout. This effect was not caused by advanced maturity, although trunk girdling slightly increased skin greasiness. Girdling reduced fruit size only on trees of low N status. The AVG applications delayed maturity and red color development by 7 to 10 days in both years compared with untreated fruit. In 1998, the combination of AVG and N fertilization delayed red color development more than either treatment alone. Fruit softening and greasiness were reduced in AVG-treated fruit harvested at the same time as untreated fruit, but this effect was not observed when AVG treated fruit were harvested at comparable maturity 7 to 10 days later. Trunk girdling and withholding N fertilizer were the best treatments for enhancing red coloration, and foliar N concentrations of ≈2.0% (W/W) resulted in better packouts compared with higher leaf N levels. AVG was an effective tool for delaying fruit maturity and maintaining fruit quality awaiting harvest, but not for improving red coloration of `Jonagold' apples.

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Anne Plotto, Anita N. Azarenko, Mina R. McDaniel, Patrick W. Crockett, and James P. Mattheis

Eating quality of `Gala' and `Fuji' apples (Malus domestica Borkh.) from multiple harvests and storage durations was assessed using an untrained consumer panel. Apples were harvested at weekly intervals for 6 weeks and stored in air. Changes due to harvest maturity and storage for overall liking (OL), sweetness, tartness, firmness, and flavor intensity were evaluated over 8 months. A multivariate factor analysis revealed multicollinearity for OL, sweetness, and flavor intensity ratings in both cultivars. These attributes had the highest loadings in the first factor, explaining 51% and 52% of the variance of `Gala' and `Fuji' data sets, respectively, and were interpreted as a quality factor. Tartness and firmness had the highest loadings in the second factor for `Gala', explaining an additional 23% of the variability and reducing that cultivar's data set to two factors. For `Fuji', however, tartness and firmness were independent and included in factors 2 and 3, respectively. Factors 2 and 3 were interpreted as maturity factors, which explained 23% and 12% of the variance. The plots of the mean factor scores provided a multivariate technique to illustrate that panelists could differentiate between the stages of maturity of apples. Canonical correlations were calculated between the sensory and instrumental data. Only firmness measurements were correlated with sensory ratings for firmness (r = 0.53 and 0.44 for `Gala' and `Fuji', respectively).

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Victorine Alleyne, James N. Moore, and J. Brad Murphy

The color and chemical composition of three strawberry (Fragaria ×ananassa Duchesne) cultivars, `Arking', `Cardinal', and Earliglow' and one advanced selection, A-7383, were examined at four maturity stages in a 2-year study. Cultivar- and maturity-related differences were observed in CIELAB color space coordinates, L*, a*, b*, anthocyanin concentration, percent soluble solids; pH, titratable acidity, sugar/acid ratio, and total solids, insoluble solids, fructose, and sucrose content. No cultivar effect was detected for glucose concentration. `Arking' and `Cardinal' had the most intense red color and were similar in L*, a*, b* values, titratable acidity, and the concentration of anthocyanin, soluble solids, total solids, and fructose. They differed significantly in pH, sugar/acid ratio, and insoluble solids. A-7383 and `Earliglow' exhibited differences in all measured characteristics except total solids. A-7383 fruits contained the lowest anthocyanin concentration and were the darkest and least red of the genotypes.

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W.R. Miller and R.E. McDonald

Solo-type papaya (Carica papaya L.) fruit at the mature green (MG) or one-quarter yellow (QY) stage of maturity were imported through the Port of Miami, Fla., and either irradiated (0.675 kGy) or not irradiated. Fruit condition and quality attributes were determined after ripening to the edible ripe stage at 25 °C before and after storage for 7 days at 10, 12, or 15 °C. The incidence and severity of peel scald was increased by irradiation regardless of storage and ripening regime; however, the degree of severity was dependent on fruit maturity at irradiation. Irradiated QY fruit tended to have the most serious incidence and severity of scald. Mature green fruit ripened at 25 °C without storage had the lowest incidence of fruit with hard areas in the pulp (“lumpy” fruit). The QY fruit generally were second only to irradiated MG fruit stored at 10 °C in incidence of lumpiness. Anthracnose sp. decay and stem-end-rots affected 53% of all fruit. The least decay occurred on fruit ripened at 25 °C without storage, regardless of fruit maturity, and the most decay occurred on QY fruit with or without irradiation. Fruit ripened at 25 °C without storage had more palatable pulp (5.5 N) at the edible ripe stage than did fruit held in storage and then ripened. The effect of fruit maturity or irradiation dose on fruit firmness, however, was dependent on the storage temperature. Mature green fruit ripened at 25 °C lost less weight than did those stored at cold temperatures prior to ripening. We recommend that importers obtain fruit with only a slight break in ground color, and distribute them as rapidly as possible, while maintaining transit/storage temperatures at or above 15 °C with or without exposure to irradiation.

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E. Echeverria, J.K. Burns, and W.M. Miller

The effect of fruit temperature and fruit maturity on the development of blossom end clearing (BEC) in Florida grapefruit (Citrus paradisi Macf. vars. Ruby Red and Marsh) was investigated. Field and storage temperature studies indicated that development of BEC was directly associated with temperature; BEC increased when fruit temperature rose above 21 °C. Cooling fruit prior to packingline operations reduced BEC significantly. Older fruit were more susceptible to BEC than were younger fruit.

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Sylvia M. Blankenship, Michael Parker, and C. Richard Unrath

`Fuji' apples (Malus domestica Borkh.) were harvested at three maturities for three consecutive seasons. Fruit firmness, soluble solids concentration, starch—iodine index (SI), and internal ethylene concentration were measured at harvest. Fruit were stored in 0 °C air storage for 8 months. Fruit firmness and other maturity indices were measured monthly during storage. Using a stepwise regression procedure, harvest maturity indices were used to predict firmness after air storage. When all maturity indices measured were represented in the model, R 2 = 0.29, 0.34, and 0.26 at 4, 6, and 8 months, respectively. Use of only SI and fruit firmness in the model gave R 2 values of 0.25, 0.29, and 0.24 for 4, 6, and 8 months, respectively. Although R 2 values were low, they were highly significant. The model using fruit firmness and SI resulted in the best fit. Thus, an equation was developed using months of air storage, firmness, and SI at harvest. Actual firmness values correlated fairly well with predicted firmness values, usually within ≈5 N. On Washington apples, predicted values were 4.3 and 3.7 N too low compared to actual firmness values after 3 or 5 months' storage. In 1993, when predicted and actual firmness values were compared for Pennsylvania apples, predicted values ranged from 2.6 to 8.3 N too high after 3 months' storage, depending on harvest date. In 1994, Pennsylvania fruit stored 4 months had predicted values 0.5 N too high to 6.3 N too low, depending on harvest date. It may be possible to develop and refine models for an apple variety that would be applicable to several regions.