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  • Author or Editor: Charles A. Sims x
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Abstract

Hand- and machine-harvested ‘Stover’ (a white Euvitis hybrid) and ‘Noble’ (a red Vitis rotundofolia cultivar) grapes were either treated with 100 mg SO2/kg (applied as potassium metabisulfite, K2S2O5) or not treated and held at ambient temperature (≈25°C) for 0, 24, and 48 hr after harvest. Raw fruit and wine quality from each treatment were evaluated. ‘Noble’ grapes of all treatments held for 24 hr had developed signs of microbial spoilage, and the machine-harvested grapes held without SO2 had the most. However, only the machine-harvested ‘Stover’ grapes held without SO2 had began to deteriorate during 24 hr. Grapes of both cultivars had deteriorated after 48 hr, but SO2 limited the deterioration of both machine- and hand-harvested grapes. In general, machine-harvested grapes deteriorated to a greater extent than hand-harvested grapes. Wines made from ‘Noble’ grapes that had been held for 0 or 24 hr had similar quality, but machine-harvested ‘Stover’ grapes held for 0 to 24 hr without SO2 produced a poorer wine than the other treatments. Wines from machine-harvested grapes held for 48 hr had poorer quality than wines from hand-harvested grapes. Postharvest additions of SO2 improved the quality of wine from machine-harvested but not hand-harvested fruit held for 48 hr.

Open Access

Grafting has many purposes in vegetable production. It is used for control of soilborne pathogens, season extension in protected culture, and improving productivity in cucurbitaceous and solanaceous crops. Consumers desire heirloom tomatoes (Solanum lycopersicum) for their perceived excellent flavor. Heirloom tomatoes are susceptible to many soilborne diseases and may benefit from grafting onto more robust, disease-resistant rootstocks especially under organic production. In this two-year study, heirloom tomato ‘Brandywine’ was grafted onto tomato hybrid ‘Survivor’ and interspecific tomato hybrid ‘Multifort’ rootstocks to determine the effects of grafting on fruit quality attributes such as soluble solids content (SSC), pH, total titratable acidity (TTA), and vitamin C. Nongrafted and self-grafted ‘Brandywine’ tomatoes were included as controls. Consumer sensory tests were also conducted to assess the effects of grafting on overall appearance and acceptability, firmness, tomato flavor, and sweetness. No significant differences in vitamin C, SSC, pH, or TTA were found in fruit from the nongrafted, self-grafted, and ‘Brandywine’ grafted with the two rootstocks either year. The SSC of all tomatoes in 2010 was lower than that of 2011. In 2010, fruit from ‘Brandywine’ grafted onto the rootstock ‘Survivor’ was scored significantly lower in appearance, acceptability, and flavor than the nongrafted ‘Brandywine’ treatment. All grafted treatments resulted in a significant decrease in acceptability ratings in the consumer sensory test. No significant differences were observed between nongrafted and grafted treatments in 2011. Consumers who reported more frequent consumption of fresh tomato tended to give lower ratings for most sensory attributes evaluated. Harvest time and fruit ripeness need to be considered in future research to better understand the influence of grafting with selected rootstocks on fruit composition and sensory attributes of heirloom tomatoes.

Full access

The effect of physiological maturity at harvest on ripe tomato (Lycopersicon esculentum Mill.) volatile profiles was studied using ripening response time (in days) to 100 μL·L-1 exogenous ethylene treatment as a tool to separate immature-green from mature-green fruit. Electronic nose (EN) sensor array and gas chromatography (GC) analyses were used to document volatile profile changes in tomatoes that required a 1-, 3-, or 5-day ethylene treatment to reach the breaker stage. EN output analysis using multivariate discriminant and canonical analyses classified intact tomato and whole tomato homogenate samples that required 3 or 5 days of ethylene treatment as significantly different (P < 0.01) from those that required only 1 day. The GC aroma profiles from whole tomato homogenate showed that 1-day fruit had significantly higher levels (P < 0.05) of 1-penten-3-one, cis-3-hexenal, 6-methyl-5-hepten-2-one, 2-isobutylthiazole, and geranylacetone when compared to 5-day fruit. Analysis of excised tomato tissues showed that pericarp (including columnella) produced an average 219% greater concentration of the 16 aroma volatiles quantified by GC when compared to locular gel (442 and 203 μL·L-1, respectively). EN analysis concurred with GC by showing greater average Mahalanobis distance between pericarp tissue groupings when compared to locular gel groupings (78.25 and 12.33 units, respectively). Pericarp tissue from the 5-day ethylene treatment showed significantly lower levels of 1-penten-3-one, trans-2-heptenal, 6-methyl-5-hepten-2-one, 2-isobutylthiazole, geranylacetone, and β-ionone compared to the 1- and 3-day treatments, Similarly, locular gel from the 3- and 5-day ethylene treatments had significantly lower levels of 1-penten-3-one, 2-isobutylthiazole, and 1-nitro-2-phenylethane compared to 1-day samples. cis-3-Hexenol in locular gel was the only volatile compound that showed significantly higher levels with increasing ethylene treatment. EN analysis showed greater Mahalanobis distances between 1- and 3-day ethylene samples than between 3- and 5-day ethylene samples (32.09 and 12.90, 24.14 and 6.52, 116.31 and 65.04, and 15.74 and 13.28 units, for intact tomato, whole tomato, pericarp, and locular gel homogenate, respectively).

Free access

The ethylene inhibitor 1-methylcyclopropene (1-MCP) delays ripening of avocado (Persea americana) and many other fruits, but there are few reports of the influence of this ethylene inhibitor on sensory attributes. The objective of this study was to evaluate the effects of aqueous 1-MCP on fruit ripening and sensory attributes of ‘Beta’ avocado, a Guatemalan-West Indian hybrid. Treatment with aqueous 1-MCP at 2.77 μmol·L−1 (150 μg·L−1) for 1 minute effectively delayed ripening by 6 days, delaying the onset of climacteric and lowering respiration rates as compared with control. Treated fruit had greener peel and firmer pulp when ripe, and untrained sensory panelists could not detect differences in texture, flavor, and overall liking between treated and untreated fruit. Immersion of ‘Beta’ avocado in aqueous 1-MCP extended the shelf life to 14 days at 20 °C and 84% relative humidity, an increase of 6 days (75%) as compared with untreated fruit, without compromising sensory acceptability. This technology has the potential to permit shipment of these fruit to more distant markets than currently possible.

Full access

The postharvest life of lettuce (Lactuca sativa) is variable and negatively affected by mechanical injury, incomplete cooling, and poor genetic quality. Lettuce breeders are developing cultivars with a longer shelf life and rely on subjective, destructive, and time-consuming methods for quality analysis. One method of accelerating quality evaluations is known as accelerated shelf-life testing (ASLT), which has the potential to assist breeders in assessing lettuce quality and shelf life. The objective of this research was to determine the quality traits that significantly affect shelf life to develop an ASLT procedure to rapidly assess the postharvest quality of lettuce accessions in breeding programs. In Test 1, Romaine lettuce quality was evaluated using one subjective and five objective parameters during storage at 5, 10, 15, or 20 °C. Results determined that weight loss, lightness*, and hue* angle were best correlated with the overall appearance rating, whereas storage at 10 or 15 °C differentiated the shelf-life potential quickly and without excessive deterioration. In Test 2, these objective characteristics and storage temperatures were used to study rates of quality deterioration of a commercial Romaine cultivar (Okeechobee) and a breeding line (60182), both with long shelf lives, and a Batavia lettuce cultivar (La Brillante) with a short shelf life. Lettuce was evaluated during storage at 10 °C (winter and spring seasons) or at 15 °C (winter season). Weight loss was the most appropriate quality index for lettuce at these storage temperatures for a single harvest, whereas lightness* and hue* angle were the most appropriate indices for comparing quality between harvests. To apply ASLT to postharvest assessments of lettuce, breeders and other researchers should include two controls with good and poor shelf life (similar to ‘Okeechobee’ and ‘La Brillante’, respectively) as standard baseline cultivars during storage at either 10 or 15 °C.

Open Access