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- Author or Editor: Steven A. Sargent x
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To remain competitive for federal and state funding, state cooperative extension services must proactively incorporate issues programming and performance-based budgeting. State major program (SMP) design teams, which provide linkages between clientele groups and the research base, must conduct needs assessments to adjust to this new atmosphere of accountability. A case study illustrates how one Florida SMP (FL107, vegetable production, harvest, handling and integrated pest management in Florida) restructured its design team to become more flexible and proactive to target a wider range of outcomes. While still in the implementation phase, this model has already resulted in improved communication within the organization, better addressing extension needs at county level while facilitating reporting at the state level.
Three southern highbush blueberry cultivars (Vaccinium corymbosum hybrids) were mechanically harvested (MH) or hand-harvested (HH) and commercially packed before storage for 14 days at 1 °C in two successive years. MH fruit were softer, had lower ratings for overall appearance, and lost up to 20% more fresh weight than HH fruit after 14 days storage. MH ‘Meadowlark’ had fewer soft fruit (<35%) during storage than either ‘Sweetcrisp’ or ‘Farthing’; however, the latter two cultivars had lower incidences of shrivel and weight loss. Fruit in the 2010 season were more susceptible to bruising than those from the 2009 season; however, soluble solids content (SSC), total titratable acidity (TTA), and ascorbic acid concentration remained constant during storage and between seasons. ‘Meadowlark’ had the highest sugar to acid ratio (25.0). Successful implementation of MH of southern highbush blueberries for fresh market will only be commercially feasible if harvest impacts are further reduced.
Two Guatemalan-West Indian avocado (Persea americana) hybrids (‘Monroe’ and ‘Booth 8’) were treated with an aqueous formulation of 1-methylcyclopropene (1-MCP) to determine effects on ripening and quality during storage simulating commercial shipping temperatures. Fruit harvested at preclimacteric stage were immersed in aqueous 1-MCP at 75 μg·L−1 (1.39 mmol·m−3) or in deionized water for 1 minute, stored at 10 °C for 14 days, and then transferred to 20 °C until ripe. Respiration rate, ethylene production, softening, and change in epidermal hue* angle were delayed and/or suppressed in both cultivars exposed to 1-MCP, although effects were less pronounced with Booth 8. Hue* angles for 1-MCP-treated ‘Monroe’ fruit had the highest values (darkest green peel color) of all treatments at full-ripe stage (hue* angle = 117). For control and treated ‘Monroe’ fruit respiration peaked on days 15 and 21, while ethylene production from both treatments peaked on day 16. Respiration and ethylene production peaked on day 16 for both control and 1-MCP–treated ‘Booth 8’ fruit. Fruit treated with 1-MCP consistently showed diminished respiration and ethylene peaks. Days to full-ripe stage were unaffected by treatment. ‘Booth 8’ fruit from both treatments were considered ripe (15 N whole fruit firmness) after 17 days; however, only 8% of control fruit were marketable, whereas 58% of 1-MCP-treated fruit were marketable, based on subjective appearance ratings using the Jenkins–Wehner score. The development of peel blemishes during storage was the primary cause of unmarketable fruit. ‘Monroe’ control and 1-MCP–treated fruit were soft after about 22 days and were significantly more marketable (control 70% and 1-MCP 85%). Avocados treated with 1-MCP ripened over a longer period than control fruit but maintained a higher percentage of marketable fruit.
Multi-state outbreaks of salmonellosis due to the consumption of contaminated fresh tomatoes (Lycopersicon esculentum) have recently occurred in the United States. This study investigated the survival of a five-serovar (serotype) Salmonella cocktail artificially inoculated onto tomato and packing line surfaces when held at various temperature and relative humidity (RH) combinations over 28 days. Packinghouse surfaces included stainless steel, polyvinyl chloride (PVC), sponge rollers, conveyor belts, and unfinished oak wood surfaces. Packinghouse climates were generated to simulate conditions in Florida during late spring (30 °C/80% RH) and fall/winter (20 °C/60% RH) months. Additionally, survival of Salmonella on tomatoes in standard ripening room conditions (20 °C/90% RH) was evaluated. Recovery of inocula was by a vigorous shake/hand rub method. After 28 days, Salmonella populations remained detectable on tomato surfaces regardless of environmental conditions. Inoculated Salmonella populations tested at spring conditions declined to undetectable levels on all packing line materials by day 11, with the exception of the unfinished oak, which reached undetectable levels by day 21. In contrast, inoculated Salmonella populations tested at fall/winter conditions declined to undetectable levels on sponge rollers and conveyor belts by day 7 and day 21, respectively. Stainless steel, PVC, and wood surfaces supported the survival of detectable populations of Salmonella over the 28-day sampling period. Results of this study demonstrate the potential for Salmonella to persist on tomato and packing line surfaces under common environmental conditions.
Hydrocooling was evaluated as an alternative to forced-air cooling for strawberry (Fragaria × ananassa) fruit. `Sweet Charlie' strawberries were cooled by forced-air and hydrocooling to 4 °C and held in different storage regimes in three different trials. Quality attributes, including surface color, firmness, weight loss, soluble solids, and ascorbic acid content, pH and total titratable acidity, were evaluated at the full ripe stage. Fruit hydrocooled to 4 °C and stored at different temperatures for 8 or 15 days showed overall better quality than forced-air cooled fruit, with significant differences in epidermal color, weight loss, and incidence and severity of decay. Fruit stored wrapped in polyvinylchloride (PVC) film after forced-air cooling or hydrocooling retained better color, lost less weight, and retained greater firmness than fruit stored uncovered, but usually had increased decay. There is potential for using hydrocooling as a cooling method for strawberries.
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.
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.
This study investigated the effect of ethylene treatment at high temperatures of 30 to 40 °C for up to 72 hours on subsequent ripening-associated processes in mature green ‘Sunny’ and ‘Agriset 761’ tomatoes (Solanum lycopersicum). Compared with ethylene-treated fruit at 20 °C, ethylene exposure at 30 or 35 °C stimulated ripening in terms of ethylene biosynthesis and color development, but the ethylene effect was only apparent after transfer to air at 20 °C. There were no negative effects on ripe tomato quality related to ethylene exposure at 30 or 35 °C. However, ethylene production of tomatoes was permanently impaired by ethylene exposure at 40 °C for 48 or 72 hours even after transferring fruit to air at 20 °C; these fruit exhibited slow softening and color development. Our results suggest that tomatoes perceive ethylene at 30 to 35 °C despite impairment of ripening at those temperatures, with the accelerated ripening response becoming apparent only after transferring the tomatoes to air at lower temperature.
Florida peaches (Prunus persica) typically are picked and placed in a cold room on the day of harvest, then packed and shipped the next day. This room cooling (RC) is slow, requiring ≈24 hours or more for the fruit to reach optimal temperature (6 to 7 °C). There is currently limited research on the effect of cooling practices on microbial quality of peaches, yet this study is essential for decision making in areas such as upgrading packing house facilities and the implementation of improved handling procedures. This research compared the efficacies of postharvest cooling by RC, forced-air cooling (FAC), and hydrocooling with sanitizer (HS) treatment of peaches to reduce their surface microbial population and to determine the effect on shelf life and microbial quality. Three trials for RC and two trials each for FAC and HS were performed. Following cooling, fruit were stored at 1 °C. The average aerobic plate count (APC) from field samples was 5.29 log cfu/peach, which remained unchanged after RC or FAC but was reduced significantly (P < 0.05) to 4.63 log cfu/peach after HS. The average yeast and mold counts (Y&M) from field samples (6.21 log cfu/peach) were reduced highly significantly (P < 0.001) to 4.05 log cfu/peach after HS. Hydrocooling significantly (P < 0.05) reduced the APC and Y&M counts from the peaches and showed promise in maintaining the microbiological quality of the fruit throughout storage. However, at the end of the 21-day storage period, there was no significant difference in APC or Y&M counts from peaches, irrespective of the cooling methods. Peaches that went through the hydrocooling process and were subsequently packed showed an increase (P < 0.05) in both APC and Y&M counts, while fruit that were not hydrocooled showed no such increase. Information obtained will be used to recommend the best temperature management practices for maintaining the postharvest quality of peaches. A detailed cost-benefit analysis of different cooling methods and the time interval between harvest and shipment are both necessary for a more conclusive recommendation.
Cooling procedures used by blueberry (Vaccinium sp.) growers often may include delays up to 24 hours that can damage the fruit through rough handling and adverse temperatures, thereby potentially compromising quality and, subsequently, safety. The objectives of this experiment were to compare forced-air cooling (FAC) compared to hydrocooling without sanitizer (HW) and hydrocooling with sanitizer (HS) regarding the quality and shelf life of southern highbush blueberry [SHB (Vaccinium corymbosum)] and to determine the efficacy of these treatments for reducing Salmonella in SHB. Freshly harvested SHB that were inoculated with a five-serovar cocktail of rifampin-resistant Salmonella were rapidly chilled by FAC or hydrocooling (HW and HS) using a laboratory model system. FAC did not show any significant reduction (P > 0.05) in Salmonella or in the effects on the microbiological quality of blueberries. HW and HS reduced Salmonella by ≈2 and >4 log cfu/g SHB, respectively, on day 0. These postharvest treatments were also evaluated for their ability to help maintain fruit quality throughout a storage period of 21 days at 1 °C. Hydrocooling (both HS and HW) provided more rapid cooling than FAC. Hydrocooled blueberries showed significant weight gain (P < 0.05), whereas FAC resulted in a slight, but insignificant (P > 0.05), reduction in final weight. The results of hydrocooling, both HS and HW, shown in this study could help to extend the shelf life while maintaining or increasing the microbiological quality of fresh market blueberries. Information obtained by this study can be used for developing the best temperature management practices to maintain the postharvest safety and quality of blueberries.