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Molly Felts, Renee T. Threlfall and Margaret L. Worthington

Understanding how human perception is related to physicochemical attributes strengthens identification of ripeness and marketability parameters for peaches and nectarines [Prunus persica (L.) Batsch]. Six peach and nectarine cultivars (Amoore Sweet, Bowden, Effie, Loring, Souvenirs, and White River) and three advanced breeding selections (A-827, A-850, and A-865) were harvested from trees grown at the University of Arkansas System Division of Agriculture Fruit Breeding Program in Clarksville, AR. Physical and chemical characteristics of the genotypes at harvest were as follows: fruit weight of 134.4 to 330.2 g, firmness of 7.8 to 35.8 N, soluble solids of 7.5% to 14.7%, pH of 3.3 to 4.8, titratable acidity of 0.2% to 1.1%, total sugars of 1.7 to 10.4 g/100 g, and total organic acids of 0.1 to 0.9 g/100 g. Overall, A-865 had the lowest fruit weight (134.0 g) and pH (3.3), and the highest firmness (35.8 N), soluble solids (14.7%), titratable acidity (1.1%), total sugars (10.4 g/100 g), and total organic acids (0.8 g/100 g). ‘White River’ had the largest fruit (330.2 g) and pit (11.06 g). A-850 (63.6) had the highest soluble solids/titratable acidity ratio, and ‘Bowden’ (12.7) had the lowest. A trained descriptive sensory panel (n = 10) was used to create a lexicon for Arkansas-grown fresh-market peaches and nectarines. The panel evaluated the fruit for aroma (n = 4), external appearance (n = 8), internal appearance and pit attributes (n = 6), basic tastes (n = 3), aromatics while eating fruit (n = 5), feeling factors (n = 2), and texture (n = 6). Principal component analysis explained 63.4% of the data variance attributed to texture and acidity. Of all of the physicochemical attributes, firmness had the most significant correlations with the descriptive sensory attributes, followed by fruit weight. Firmness was negatively correlated (r = −0.70 to 0.81) to fruit size, fuzziness, amount of bruises on the flesh, pit size, and moisture release, and positively correlated (r = 0.68–0.84) to sourness, green/unripe aromatics, flesh hardness, flesh crispness, and fibrousness between the teeth. Fruit weight was positively correlated (r = 0.67–0.75) to fruit and pit size, overripe aromatics, and moisture release. Significant correlations between descriptive sensory appearance, basic tastes, aromatics, and texture attributes with physicochemical attributes provide an indication of ripeness and marketability parameters for peaches and nectarines. These descriptive attributes are quality factors that impact consumer purchases and perception of fresh-market peaches and nectarines.

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Derek W. Barchenger, John R. Clark, Renee T. Threlfall, Luke R. Howard and Cindi R. Brownmiller

Muscadine grapes (Vitis rotundifolia Michx.) are native to the southeastern United States and have potential for greater fresh-market sales if postharvest storage can be improved, but limited information is available on postharvest storability. In 2012 and 2013, physiochemical and storability attributes were measured in 17 muscadine genotypes (selections and cultivars) from the muscadine breeding program at the University of Arkansas or commercial cultivars. The postharvest and physiochemical attributes of the muscadines were measured at harvest and during storage for 3 weeks at 2 °C. Nutraceutical compounds were measured initially after harvest. As a result of extreme differences in weather in 2012 and 2013, the data were analyzed by year. Genotypes significantly affected storage attributes [weight loss (%), and unmarketable berries (%)] and physiochemical attributes such as penetration force (force to penetrate berry skin), titratable acidity (TA), pH, soluble solids (%), berry color (L*, chroma, and hue) as well as the nutraceutical compounds. The postharvest attributes of weight loss and unmarketable berries and the physiochemical attribute of penetration force were significantly affected by postharvest storage, but berry composition attributes remained fairly constant during storage. Overall, University of Arkansas selections AM 04, AM 26, AM 28, and the cultivar Southern Jewel had the highest potential for postharvest storage, whereas the genotypes AM 01, AM 15, AM 18, and ‘Nesbitt’ had the least potential. Genotypes AM 03, AM 04, AM 27, and ‘Ison’ had the highest nutraceutical contents [total anthocyanins, total phenolics, total flavonols, resveratrol, and oxygen radical absorbance capacity (ORAC)], whereas AM 18, AM 28, ‘Supreme’, and ‘Tara’ had the lowest contents. Postharvest storage potential, berry composition, berry color, and nutraceutical content were genotype-specific, but commercially viable genotypes were identified that can provide genetic material for breeding programs and postharvest evaluation protocol for commercial use.

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Derek W. Barchenger, John R. Clark, Renee T. Threlfall, Luke R. Howard and Cindi R. Brownmiller

A major limiting factor in fresh-market muscadine grape (Vitis rotundifolia Michx.) commercialization is fruit deterioration during storage. Research on table grapes has shown that field fungicide applications increase storability, but little is known of their effect on muscadines. The effect of field applications of fungicides on physicochemical attributes during postharvest storage and nutraceutical content at date of harvest was evaluated on five muscadine cultivars (Nesbitt, Southern Jewel, Summit, Supreme, and Tara) and four breeding selections from the University of Arkansas Fruit Breeding Program in 2012 and 2013. There were two field treatments (no fungicide and fungicide). For the fungicide treatment, alternating applications of two fungicides were applied to the vine at 14-day intervals during berry maturation. Fruit was harvested and physicochemical attributes including berry volume, titratable acidity (TA), pH, soluble solids (%), color (L, chroma, and hue), firmness (force to penetrate berry skins and flesh), storage weight loss (%), and unmarketable fruit (%) were evaluated every 7 days for 3 weeks. Whole muscadine berries were analyzed for nutraceutical content only for the date of harvest. As a result of less decay, less weight loss, and greater firmness during storage, AM 27, ‘Southern Jewel’, and ‘Supreme’ had the highest potential for postharvest storage, whereas AM 01, AM 15, and ‘Tara’ had the least potential. Nutraceutical content varied by genotypes; overall AM 27 had the highest nutraceutical content [sum of anthocyanins, total phenolics, flavonols, resveratrol, and oxygen radical absorbane capacity (ORAC)], whereas ‘Supreme’ and AM 28 had the lowest. Total anthocyanins were only found in the black genotypes and total phenolics and resveratrol were unaffected by fungicide treatment. Total ellagitannins varied among the fungicide treatments. Total flavonols were generally greater in the no fungicide treatments, whereas ORAC was generally greater with fungicide treatments. Year of study and genotype were determined to be major contributors as sources of variation. Although field fungicide applications did not affect all postharvest attributes and nutraceutical components, differences among genotypes and fungicide treatments did occur.

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Daniela M. Segantini, Renee T. Threlfall, John R. Clark, Luke R. Howard and Cindi R. Brownmiller

Fresh-market blackberries (Rubus subgenus Rubus Watson) have a growing global market, with continued release of cultivars to meet demand for consumer-quality fruit. The release of primocane-fruiting blackberry plants that produce crops on both floricanes and primocanes has expanded blackberry production. This study investigated the physiochemical attributes of fresh-market blackberries harvested from two cane types (floricane and primocane) from four primocane genotypes (APF-238, APF-268, ‘Prime-Ark® 45’, and ‘Prime-Ark® Traveler’) grown at the University of Arkansas Fruit Research Station, Clarksville in 2015 and 2016. Year-to-year differences were evident as blackberries harvested in 2016 were smaller (6 g) and less acidic (0.7% titratable acidity) than berries harvested in 2015 (8 g berries with 0.9% titratable acidity); however, soluble solids in each year were similar (≈10.2%). Differences in genotypes were also a factor. ‘Prime-Ark® Traveler’ (2015) and APF-268 (2016) had the highest berry firmness (7.8–8.3 N). In both years, APF-238 had the lowest firmness (5.7–6.0 N), highest isocitric acid (0.8–1.1 g/100 g), and highest total anthocyanins (239–353 mg/100 g). Floricane fruit harvested from ‘Prime-Ark® Traveler’ had the highest berry weights (8.3–10.4 g) in both years. Blackberries harvested from primocanes were wider (21.3–22.9 mm), had higher soluble solids (11.6% to 12.6%), and had lower titratable acidity (0.6%) when compared with floricane fruit in both years. Major year-to-year differences were found for several variables in this study, indicating that environmental effects can be substantial and growers should be aware of this influence on berries harvested from the different cane types. Evaluation of quality properties of floricane and primocane fruit of primocane plants in other locations would be valuable, particularly from areas where commercial blackberry production is established.

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Molly Felts, Renee T. Threlfall, John R. Clark and Margaret L. Worthington

Understanding how consumer perception is related to physiochemical attributes assists in the identification of harvest and marketability parameters for muscadine grapes (Vitis rotundifolia Michx.). Three muscadine cultivars (Ison, Nesbitt, and Summit) and three advanced breeding selections (AM-9, AM-74, and AM-83) were harvested from vines at the University of Arkansas System Division of Agriculture Fruit Research Station in Clarksville, AR. The physiochemical (physical and composition) and sensory attributes (descriptive) of the genotypes were evaluated at harvest. Significant differences between genotypes were observed for berry weight (9.25–14.38 g), soluble solids (12.73% to 15.40%), pH (2.88–3.33), titratable acidity (0.54% to 1.01%), soluble solids/titratable acidity ratio (13.12–28.49), skin firmness [0.85–1.48 Newtons/millimeters (N·mm−1)], and flesh firmness (0.89–2.14 N). Total sugars (6.17–9.75 g/100 g) and total organic acid (0.50–0.84 g/100 g) levels were not significantly different for these genotypes. A trained descriptive sensory panel (n = 8) evaluated the fruit attributes for aroma (n = 9), external appearance (n = 7), internal appearance (n = 3), basic tastes (n = 3), aromatics (n = 10), feeling factors (n = 2), and texture (n = 7). The descriptive sensory panel detected differences among genotypes for external appearance, internal appearance, and basic taste attributes, more specifically with desirable attributes rather than unfavorable. However, the panelists found no differences among genotypes for texture attributes. Of the physiochemical attributes, total sugars had the most significant correlations with the descriptive sensory attributes, followed by soluble solids/titratable acidity ratio. Total sugars were correlated to 12 attributes (three aromas, two exterior appearances, two basic tastes, four aromatics, and one feeling factor) and soluble solids/titratable acidity was correlated to five attributes (one aroma, one basic taste, two aromatics, and one feeling factor). A lexicon of terms for descriptive sensory attributes for fresh-market muscadine grapes was established. This lexicon can be used for other research and breeding efforts, as well as establishing the relationship between the physiochemical and descriptive sensory attributes.

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Teresa L. Walker, Justin R. Morris, Renee T. Threlfall, Gary L. Main, Olusola Lamikanra and Stephen Leong

Muscadine grapes (Vitis rotundifolia Michx.), native to the southeastern United States, have a distinct flavor, and grocers are interested in marketing them as table grapes. Two studies using 'Fry' muscadines were conducted to assist the muscadine industry in providing quality table grapes. Study 1 (1998 and 1999) evaluated density sorting and relationships between maturity, color, soluble solids, firmness, shelf life, and sensory evaluation of grapes. Study 2 (1998) determined the effect of storage on quality attributes of different maturities of grapes and evaluated use of polyethylene bags to extend their storage. Density separation successfully sorted grapes by maturity. Muscadine berry color may allow for visual or electronic sorting to eliminate immature fruit. Sensory panelists could distinguish differences in maturities for all sensory attributes. In 1999 maturities 3 and 4 (≈24-33 soluble solids: acid ratio) were preferred overall by panelists. As maturity increased, soluble solids and pH increased, and acidity decreased. Firmness decreased as maturity and storage at 2 °C increased. Percent decay increased with maturity and storage time. Grapes stored in polyethylene bags had reduced decay. A chart developed from the 1999 data related berry color to soluble solids: acid ratio, soluble solids, tartaric acid, and pH. Data from these studies can be used by industry to establish harvest parameters and enhance marketability of 'Fry' muscadine grapes.

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R. Keith Striegler, Chris B. Lake, Justin R. Morris, Renee T. Threlfall, Gary L. Main and Simon G. Graves

'Sunbelt' is a juice grape cultivar developed by the Univ. of Arkansas. This cultivar produces 'Concord'-type juice and is adapted to warm climatic conditions of the southern United States. Preliminary evaluation showed that 'Sunbelt' has potential to produce high-quality juice under the hot climatic conditions of the San Joaquin Valley. A study was conducted during the 1998 and 1999 growing seasons to further evaluate the adaptation of 'Sunbelt' to the San Joaquin Valley and determine the response of this cultivar to selected pruning methods. Vines were grown for two seasons without use of insecticides, fungicides, or herbicides. Vines were subjected to four pruning treatments: severe hand pruning (60-80 nodes retained/vine); moderate hand pruning (120-160 nodes retained/vine); machine pruning with hand follow-up (160-180 nodes retained/vine); and minimal pruning (200-400 nodes retained/vine). Vines were trained to a Geneva Double Curtain trellis system. Yield, components of yield, and juice quality were significantly impacted by pruning treatment. In both seasons, mechanized systems of pruning (machine and minimal) produced higher yield than hand pruning. Minimal pruning resulted in the highest yield (42 t·ha-1) in 1998, while yield from the machine-pruned vines was highest (29 t·ha-1) in 1999. Minimally pruned vines had the highest clusters/vine and lowest cluster weight among the treatments. The extremely high yields obtained for the minimal pruning treatments produced fruit that was less mature resulting in juice with lower soluble solids than the other treatments in 1998. However, in 1999 the juice from minimally pruned vines had the highest soluble solids. Sensory analysis of juice produced in 1999 showed that the juice from the machine-pruned treatment had the least color intensity. Sensory analysis showed that minimal and severe hand pruning were ranked higher for sweetness than machine and moderate hand pruning. In the second year of the study, the juice from the minimal-pruned and severe hand-pruned treatment were preferred over the moderate hand-pruned treatment or the machine-pruned treatment.

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R. Keith Striegler, Justin R. Morris, Gary L. Main, Chris B. Lake, Simon R. Graves, Renee T. Threlfall and Janice M. Blevins

`Sunbelt' is a juice grape cultivar developed by the Univ. of Arkansas. This cultivar produces `Concord'-type juice and is adapted to climatic conditions of the southern United States. Preliminary evaluation showed that `Sunbelt' has potential to produce high-quality juice under the hot climatic conditions of the San Joaquin Valley. A study was conducted during the 1998 and 1999 seasons to further evaluate the adaptation of `Sunbelt' to San Joaquin Valley conditions and determine the response of this cultivar to selected pruning methods. Vines of uniform vine size and vigor were subjected to four pruning treatments: severe hand-pruning (60 to 80 nodes retained/vine); moderate hand-pruning (120 to 160 nodes retained/vine); machine-pruning (160 to 180 nodes retained/vine); and minimal pruning (200 to 400 nodes retained/vine). Vines were trained to a Geneva Double Curtain trellis system. Yield and components of yield were significantly impacted by pruning treatment. In both seasons, mechanized systems of pruning (machine or minimal) produced higher yield than hand pruning. Minimal pruning resulted in the highest yield in 1998, while yield from machine-pruned vines was highest in 1999. Minimally pruned vines had the highest clusters/vine, lowest cluster weight, and lowest berry weight among the treatments. Fruit composition was also affected by pruning treatment. Minimal pruning produced fruit which was less mature than fruit from the other treatments in 1998. This result was likely due to the high yield obtained. Few differences in fruit composition were observed among treatments in 1999. The effect of pruning method on processed juice quality will be presented. Acceptable juice quality was obtained for most treatments.

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Renee T. Threlfall, Olivia S. Hines, John R. Clark, Luke R. Howard, Cindi R. Brownmiller, Daniela M. Segantini and Lydia J.R. Lawless

Blackberries (Rubus subgenus Rubus Watson) are grown worldwide for commercial fresh markets. Physiochemical and sensory attributes were evaluated on fresh fruit of five blackberry cultivars (Natchez, Osage, Ouachita, Prime-Ark® 45, and Prime-Ark® Traveler) and six advanced breeding selections from the University of Arkansas Fruit Breeding Program. The physiochemical attributes of blackberries were within a commercially acceptable range (soluble solids = 8% to 11%, pH = 3.0–3.6, titratable acidity = 0.7% to 1.4%, berry weight = 6 to 14 g, drupelets/berry = 50 to 150, and pyrenes/berry = 51 to 115). ‘Natchez’ had the highest berry weight, berry length, drupelets/berry, and pyrenes/berry, whereas A-2453 was the lowest for these attributes. The highest nutraceutical levels were found in ‘Osage’ (total flavonols and total anthocyanins), A-2434 (total ellagitannins) and A-2453 (total phenolics). A trained descriptive sensory panel (n = 9) evaluated fresh blackberry attributes for appearance, basic tastes, feeling factors, aromatics, and texture using a 15-point scale (0 = less of the attribute; 15 = more of the attribute in terms of intensity). The descriptive panel identified ‘Natchez’ as having the largest descriptive size of berry with the highest overall aromatics and A-2453 as the smallest, glossiest, and firmest. Although A-2491 had the highest soluble solids, the descriptive panelists could not differentiate sweetness among the genotypes, but found A-2491 the least sour. A consumer sensory panel (n = 74) evaluated appearance, flavor, and texture attributes of blackberries on a 9-point verbal hedonic liking scale (1 = extremely dislike; 9 = like extremely) and 5-point just about right (JAR) scale (1 = not nearly enough; 3 = JAR; 5 = much too much). In terms of overall impression and overall flavor, A-2491 and ‘Prime-Ark® Traveler’ had the highest liking; average attributes for these blackberries were a berry weight of 9.1 g, soluble solids of 10.0%, titratable acidity of 0.95%, and a soluble solids/titratable acid ratio of 11.9. ‘Prime-Ark® Traveler’ also had the highest liking for appearance and berry size. A-2453, the glossiest berry, had the highest liking for berry color. Consumer panelists liked the firmness of the blackberries including those that were very firm, such as A-2453, but did not indicate differences in liking among genotypes. Consumers found the size of ‘Ouachita’, ‘Prime-Ark® Traveler’, and ‘Prime-Ark® 45’ (berry weight ≈8.3 g) JAR, but ‘Natchez’ (14.3 g) too large. Consumers found the sweetness and sourness of A-2491 JAR. Consumer overall impression and flavor of blackberries were positively correlated to consumer liking of berry shape and color and negatively correlated to the descriptive attributes for sourness, bitterness, green/unripe aromatic, and amount of seeds. Consumer liking of appearance was positively correlated with consumer liking of berry size, shape, color, and descriptive uniformity of color and glossiness. To produce a commercially marketed fresh-market blackberry, there are many characteristics that are important, but our data for these genotypes suggest that a desired blackberry should have a berry weight of 8–10 g, soluble solids of 9% to 11%, titratable acidity of 0.9% to 1%, and a soluble solids/titratable acid ratio of 10 to 13. However, optimum sugar and acidity levels require more investigation including other factors in flavor and aromatics. Evaluating the physiochemical and sensory attributes of fresh fruit is an important tool that can be used to determine commercial potential for selections and cultivars.