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  • Author or Editor: Elizabeth Baldwin x
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Fruit of 40 genotypes of Capsicum frutescens L. from the US Department of Agriculture/Agricultural Research Service Capsicum germplasm collection were analyzed for a variety of fruit quality parameters, including fruit size, weight, and concentrations of capsaicinoids, sucrose, glucose, fructose, malic acid, and total acid equivalents. Fruit weight ranged from 0.23 g fresh weight to 4.04 g fresh weight (average 1.05g). Fruit length/width ranged from 1 to 8.0 (average, 3.61). Capsaicin concentrations ranged from 34 to 350 mg·100 g−1 fresh weight (average, 135 mg·100 g−1 fresh weight). Sucrose concentrations ranged from 0.28 to 1.0 g·100 g−1 (average, 0.6 g·100 g−1 fresh weight). Total sugar extracts ranged from 0.73% to 2.6% (average, 1.55%). Malic acid concentrations and total acid equivalents ranged from 0.62 to 2.29 g·100 g−1 fresh weight (average, 2.07 g·100 g−1 fresh weight) and 0.97 to 3.31 g·100 g−1 (average, 1.87 g·100 g−1) respectively. These data demonstrate an approximate 4 to 14-fold range in values for the characteristics examined, suggesting the presence of sufficient variability for these traits within this species to support the development of germplasm enhanced for specific or multiple fruit quality attributes.

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Warm field temperatures can often result in poor peel color of some citrus varieties, especially early in the harvest season. Under these conditions, Florida oranges, temples, tangelos, and K-Early citrus fruit are allowed to be treated with Citrus Red No.2 dye (CR2) to help produce a more acceptable peel color. Unfortunately, CR2, the commercial colorant used in Florida, has been listed as a group 2B carcinogen by the European Union (EU) and the International Agency for Research on Cancer (IARC). Although not likely dangerous at levels used on citrus, and on a part of the fruit that is not ingested, there is a negative health perception, and thus, a need for natural or food grade alternative colorants to replace CR2 for use on citrus. This research demonstrated that three out of five oil-soluble natural red/orange colorants resulted in peel colors somewhat similar to the industry standard CR2. These three (annatto extract, paprika extract, and paprika oleoresin) were selected for further in vivo studies. The stability of the natural colorants along with CR2 was evaluated by applying them on test papers and then on fresh ‘Hamlin’ oranges. All natural colorants were found to be easily oxidized and faded when applied on test papers. However, coating the colored surfaces with carnauba wax apparently inhibited oxidation and the subsequent discoloration of the surface. When applying the natural colorants to ‘Hamlin’ oranges before waxing, the treatments retained the improved color after storage in the dark at 5 °C, simulating cold storage. However, only annatto extract maintained a stable color when subsequently stored in a simulated market condition, at 23 °C exposed to 300 lx of standard fluorescent white light.

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Both refrigeration and blanching of red-stage tomatoes are common practices in Japan home kitchens and in food service operations. However, little is reported on the impact of such practices on aroma profiles in tomato fruits. In this study, ‘FL 47’ tomatoes at red stage were dipped in 50 °C hot water for 5 minutes or exposed to 5 °C for 4 days to simulate consumer handling of tomato in food service or home kitchens, respectively. Of the 42 volatile compounds detected, refrigeration generally suppressed production of aldehydes, alcohols, oxygen-containing heterocyclic compounds, and nitrogen- and oxygen-containing heterocyclic compounds, including the following abundant and/or important volatiles: pentanal, 3-methylbutanal, 2-methylbutanal, hexanal, cis-3-hexenal, trans-2-hexenal, 2-phenylacetaldehyde, pentanol, 3-methylbutanol, 2-phenylethanol, 1-penten-3-one, geranial, and geranylacetone. On the other hand, the production of aldehydes, alcohols, hydrocarbons, oxygen-containing heterocyclic compounds, and nitrogen- and oxygen-containing heterocyclic compounds was reduced by blanching, associated with low concentrations of 2-methylbutanal, pentanal, cis-3-hexenal, trans-2-hexenal, 2-phenylacetaldehyde, pentanol, 2-methylbutanol, and 2-phenylethanol. These results indicate that a short blanching or refrigeration of tomatoes substantially impacts tomato aroma quality.

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Thirty-eight tomato (Solanum lycopersicum L.) genotypes were analyzed for sensory attributes “sweet,” “sour,” and “overall flavor” over 7 years, one to three seasons per year (March, June, and December) as well as for physical and chemical flavor-related attributes including color, sugars, acids, and aroma volatiles (6–7 years). Principal component analysis of the data of nine genotypes showed that for harvest season, December-harvested fruit were generally associated with more acids and sourness perception and less sugars and sweetness perception and, therefore, lower overall flavor ratings compared with June-harvested fruit. March-harvested samples were intermediate. Despite the seasonal variations, there were significant differences between genotypes for sensory perception of sweetness, sourness, and flavor, between seasons for sourness and flavor, and between years for flavor, with some interactions between genotypes, seasons, and years. In addition to sugar and acid measurements, 29 aroma volatiles were evaluated in 33 genotypes over the seasons. Eleven volatiles were found to positively correlate with flavor perception and 13 enhanced flavor along with the soluble solids/titratable acidity ratio in a two-predictor model, providing aroma targets for breeders. Among the genotypes evaluated most frequently were the Florida industry standard ‘Florida 47’ and University of Florida hybrid ‘Fla. 8153’ which was released in 2006 and is now marketed as Tasti-Lee®. ‘Florida 47’ was almost always rated lower for sweet and overall flavor compared with ‘Fla. 8153’. On a 1–9 hedonic scale, where 1 was least sweet, sour, or flavorful and 9 was most sweet, sour, or flavorful, average scores over the 7 years were 3.8 and 5.1 for sweet and 4.1 and 5.7 for overall flavor for ‘Florida 47’ and ‘Fla. 8153’, respectively. Other genotypes related to ‘Fla. 8153’, including its parents, were also rated high for sweet and overall flavor compared with ‘Florida 47’ and other commercial cultivars grown in Florida. Correspondingly, sugar measurements were higher, while acid measurements were slightly lower for ‘Fla. 8153’ compared with ‘Florida 47’. Thirteen out of 29 aroma compounds showed differences between these two genotypes, with eight being higher in ‘Fla. 8153’ (including many fruity/floral notes) and four higher in Florida 47 (C-5 and C-6 aldehydes and alcohols giving green notes). This provides a useful chemical model for two genotypes that differ in flavor quality that can be exploited by breeders seeking to improve flavor.

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In Florida, early season citrus fruits usually reach full maturity in terms of internal quality while their peel often does not turn to orange color after degreening due to insufficient buildup of carotenoids. For huanglongbing (HLB)-affected orange trees, the fruit may never turn orange during the entire harvest season, despite any cold weather. Improvement of early season citrus peel color is important to the citrus industry to better meet consumer expectations. Occasionally, packinghouses apply a dye, Citrus Red No. 2 (CR2), to improve the surface color of oranges, temples, and tangelos before applying a fruit wax to impart shine, retain moisture, and slow fruit senescence. In a previous report, we determined that paprika and annatto extracts are comparable to CR2 as natural colorant alternatives. In this research, the goal was to formulate a natural colorant [annatto, paprika, or paprika oleoresin (PO)]-containing carnauba wax coating. The coatings were first evaluated for color, shine, moisture retention, respiration rate, ethylene production, and internal gas content. Control fruit were coated with carnauba wax alone, or dyed with CR2 then coated with carnauba wax. The effects were assessed under different temperature and light exposure conditions to simulate commercial storage and marketing. The results showed that a one-step application of paprika-containing carnauba wax was comparable to the two-step (“CR2 then wax”) applications in improving fruit appearance and modification of internal gas composition.

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Six ‘Ambersweet’-derived hybrids, similar to sweet orange fruit size, color, and taste and potential as new sweet orange cultivars, were selected to determine their fruit categorization by comparison of their volatile profiles with the parent and ‘Hamlin’, a typical sweet orange. All hybrids are at least ½ sweet orange and varying amounts of mandarin, grapefruit, Poncirus trifoliata, and sour orange in each pedigree. In total, 135 volatiles were detected in the eight hybrid lines/commercial cultivars over two harvests, and 20 compounds were detected in all samples, including terpenes (limonene, β-myrcene, α-pinene, α-terpinene, α-terpineol, and linalool), esters (ethyl butanote, ethyl pentanoate, and ethyl acetate), aldehydes (acetaldehyde, hexanal, and nonanal), and alcohols (ethanol and hexanol). Total abundance of volatiles in January-harvested fruits averaged 30% higher than for fruits of the same trees harvested in November. ‘Ambersweet’ contained the highest total amount of volatiles (mainly as a result of very high levels of monoterpenes), and of them, nootkatone and six other compounds were not detected in any of the hybrids, and some of them were also not detected in ‘Hamlin’. On the other hand, 12 compounds, including pentanal, ethyl 2-butenoate, and ethyl nonanoate, were not detected in ‘Ambersweet’ but were found in ‘Hamlin’ and some of the hybrids. Cluster analysis separated the cultivar/hybrid and harvest time combinations into three clusters. FF-1-76-50, FF-1-76-52 and January FF-1-75-55, all with the same parents (‘Ambersweet’ × FF-1-30-52), were close to FF-1-65-55, but they were separated from ‘Hamlin’ and further separated from ‘Ambersweet’. The cluster containing ‘Hamlin’ has three subclusters: January ‘Hamlin’ and November FF-1-74-14, a hybrid with one-eighth P. trifoliata, which includes a slight off-flavor frequently found in P. trifoliata hybrids, independent of each other, and both were separated from a group of November ‘Hamlin’, FF-1-64-97, and FF-1-75-55. The cluster containing ‘Ambersweet’ included January FF-1-64-97. A principle component analysis (PCA) separated ‘Ambersweet’ from all hybrids and ‘Hamlin’ along the PC1 axis and separated November harvests from January harvests along PC2. This volatile analysis supports the classification of the hybrids as sweet orange.

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The capacity for 1-methylcyclopropene (1-MCP) to inhibit color change and firmness loss and alter aroma profiles for tomato (Lycopersicon esculentum Mill.) fruit was evaluated as a function of 1-MCP concentration, multiple and continuous applications, and stage of ripeness. In addition, the relationship between external and internal fruit color and firmness was determined. 1-MCP reduced the rate of red color development in fruit of all stages of ripeness. A single application of 1-MCP delayed color development by ≈ days. A second application of 1-MCP 10 days after first treatment additionally delayed color development of mature green fruit by another 8 to 10 days. Continuous 1-MCP application completely inhibited color development of breaker and half-ripe fruit for the duration (34 days) of application, but only partially inhibited firmness loss. When fruit at 50% color development were treated with 1-MCP, gel color development tended to lag behind the external fruit color change compared to nontreated fruit. Some aroma volatiles were affected by 1-MCP applied at the mature green and breaker stages, but the effect was relatively minor; 1-MCP did not affect sugar or titratable acid levels in these fruit. Collectively, the data indicate 1-MCP caused minor shifts in the quality attributes of locule color, aroma, and firmness relative to external color, which may reduce the value of this treatment, but benefits accrued by slowed firmness loss and color development may afford sufficient compensation to make 1-MCP application commercially feasible.

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Three citrus hybrids, containing 50% to 75% sweet orange (Citrus sinensis) genome in their pedigrees and similar to sweet orange in fruit size, color, and taste, were tested for their potential to be classified as new “sweet orange” cultivars. ‘Hamlin’, ‘Midsweet’, and three other early to midseason sweet oranges, along with ‘Dancy’ tangerine (Citrus reticulata), a typical mandarin, were used for comparison. Fruit were picked on 23 Jan. 2014, 30 Dec. 2014, and 27 Jan. 2015. A total of 114 volatiles were detected and separated into seven groups by detection frequency: three groups with 43 volatile components did not show differences and thus contributed little information for classification of sweet orange vs. mandarin, and the remaining four groups with 71 volatiles contributed to distinctions between orange and mandarin. Among the hybrids, the pattern of volatile detection frequency for hybrid FF-1-74-52 was virtually identical to sweet orange, and cluster analysis agreed with the classification. The number of average peaks were 55 to 62 in sweet oranges, 67 in FF-1-74-52, and 17 to 37 in tangerine and other hybrids. Quantity analysis of individual volatiles and chemical classes indicated that FF-1-74-52 and sweet oranges were rich in total volatile abundance, and almost all chemical classes including mono and sesquiterpenes, aldehydes, alcohols, ketones, and esters. This was especially true for ethyl butanoate, which contributes a fruity top note, and valencene and all sesquiterpene hydrocarbons, which only contribute to citrus flavor indirectly through their contribution to headspace partitioning. Two other hybrids, FF-1-75-55 and FF-1-76-51, each had some similarity to sweet oranges in several chemicals and classes, but not in the overall volatile profile. All three sweet orange–like hybrids met the standards for mandarins and oranges in soluble solids content, titratable acidity (TA), and the ratio. The above volatile and nonvolatile flavor chemical profile comparisons strongly support a proposal to classify FF-1-74-52 as a “sweet orange” commercially, and all three hybrids were previously shown to be more similar to sweet orange in their volatile profile than is ‘Ambersweet’. ‘Ambersweet’ was a hybrid that was legally classified as a “sweet orange” in 1995 based on its volatile profile.

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Tomato (Lycopersicon esculentum Mill.) fruit, cv. Solar Set, were harvested at the mature-green stage and treated with 50 μL·L-1 ethylene at 20 °C. Individual fruits at the breaker stage (<10% red color) were dropped onto a solid surface to induce internal bruising. Dropped and undropped fruit were stored at 20 °C until red-ripe, at which time pericarp, placental, and locule tissues were excised. Tissues from dropped tomatoes were examined for evidence of internal bruising and all tissues were analyzed for selected volatile profiles via headspace analysis. Individual volatile profiles of the three tissues in bruised fruit were significantly different from those of corresponding tissues in undropped, control fruit, notably: trans-2-hexenal from pericarp tissue; 1-penten-3-one, cis-3-hexenal, 6-methyl-5-hepten-2-one, cis-3-hexenol and 2-isobutylthiazole from locule tissue; and 1-penten-3-one and β-ionone from placental tissue. Alteration of volatile profiles was most pronounced in the locule tissue, which was more sensitive to internal bruising than the other tissues. Changes observed in the volatile profiles appear to be related to disruption of cellular structures.

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