Improved Firmness Retention Research Articles

Role of UV-C irradiation scheme on cell wall disassembly and surface mechanical properties in strawberry fruit

UV-C treatments have been reported to prevent firmness loss and decay in part by delaying the degradation of fruit structural barriers. The influence of the irradiation regime on wall disassembly has not been determined. We evaluated the influence of single pre-storage and repeated-low dose UV-C treatments on strawberry mechanical properties and cell wall degradation. Ripe strawberry was subjected to Single-Step UV irradiation (4 kJ m-2 prior to storage); Two-Step UV irradiation: two 2 kJ m−2 treatments after 0 and 4 days at 0 °C and Multi-Step UV irradiation: five 0.8 kJ m−2 UV-C applications every 2 days until day 8 at 0 °C. A non-irradiated group was used as a control. During storage we determined the changes in surface mechanical properties, hemicellulose and pectin solubility-β-glucanase-β-glucosidase, (Glcase) α-xylosidase (Xylase), polygalacturonase, (PG); pectinmethylesterase (PME), α-arabinofuranosidase (AFase), and β-galactosidase (β-gal) activities. UV treated berries showed higher surface hardness and resistance to compression and tolerated greater compression distance to tissue failure. Softening was more effectively reduced in fruit receiving Two-Step and Multi-Step irradiations. Though all UV-C treatments transiently decreased PG, PME and Glcase activities, the improved firmness retention found after Two-Step and Multi-Step irradiation was related to the inhibition of Xylase and β-gal. Repeated low dose UV exposure prevented softening by delaying pectin solubilization.

Application of biocomposite edible coatings based on pea starch and guar gum on quality, storability and shelf life of ‘Valencia’ oranges

Novel edible composite coatings based on pea starch and guar gum (PSGG), PSGG blended with lipid mixture containing the hydrophobic compounds shellac and oleic acid (PSGG-Sh), and a layer-by-layer (LBL) approach (PSGG as an internal layer and shellac as an external layer), were investigated and compared with a commercial wax (CW) and uncoated fruit on postharvest quality of ‘Valencia’ oranges held for up to four weeks at 20°C and 5°C with an additional storage for 7 d at 20°C. The incorporation of lipid compounds into the PSGG coatings (PSGG-Sh) generally resulted in the best performance in reducing fruit respiration rate, ethylene production, weight and firmness loss, peel pitting, and fruit decay rate of the coated oranges. Fruit coated with PSGG-Sh and a single layer PSGG coatings generally resulted in higher scores for overall flavor and freshness after four weeks at 5°C followed by one week at 20°C than uncoated fruit, as assessed by a sensory panel. Although the LBL coating reduced weight loss and respiration rate with improved firmness retention to a greater extent than the single layer PSGG coating, the bilayer coating also resulted in higher levels of ethanol causing increased perception of off-flavors. Overall results suggested that PSGG-based edible coatings could be a beneficial substitute to common commercial waxes for maintaining quality and storability, as well as extending shelf life of citrus fruit and potentially other fresh horticultural produce.

Effect of monochromatic Far-Red light on physical-nutritional-microbiological attributes of red tomatoes during storage

Red tomatoes exposed for one month to monochromatic Far-Red Light (FRL 740nm) and darkness, respectively at 10°C were subjected to physical-nutritional-microbiological investigations. The stimulation of wax biosynthesis corroborated with the widening of hydrophobic fraction in the tomatoes wax composition, the narrowing of the diameter and aperture of pericarp cells in tomatoes cuticle during FRL exposure result in tighter cuticle-wax adhesion, enhanced barrier properties against transpiration and improved firmness retention. Moreover, the storage in FRL proves to be more effective as compared to that in darkness in terms of browning index, titratable acidity and ascorbic acid level. Discoloration in the skin of FRL-exposed tomatoes in the end of storage was more pronounced than that of darkness-exposed tomatoes, as result of lycopene content reduction to a greater extent. A significant diminishing in the surface colonization with yeasts and molds was observed in the FRL-exposed tomatoes as compared to those exposed in the darkness. The results are relevant both from the industrial and consumership points of view. The positive influence of FRL on attributes of red tomatoes in storage can be addressed to improve the illumination in warehouses reflected in the prolongation of tomatoes shelf life and nutritional value, reducing of food waste and financial loss.

Effects of multiple 1-methylcyclopropene treatments on apple fruit quality and disorders in controlled atmosphere storage

The objective of this study was to investigate the effects of multiple 1-methylcyclopropene (1-MCP) treatments on fruit quality and disorder development in apples, with a second 1-MCP treatment applied after several months of controlled atmosphere (CA) storage. ‘McIntosh’, ‘Empire’, and ‘Northern Spy’ apples were harvested from commercial orchards and cooled overnight to 3°C. 1-MCP (1μLL−1) was applied 2d after harvest and then again to half of the fruit after 4 months of CA storage. ‘Northern Spy’ apples also received a single 1-MCP treatment after 4 months of CA storage. Similar fruit from all cultivars were also not treated with 1-MCP. ‘McIntosh’ and ‘Empire’ were held at 3°C and ‘Northern Spy’ at 0°C for 9 months in CA storage (2.5kPa O2+2kPa CO2 for ‘Empire’, 2.5kPa CO2 for ‘Northern Spy’, and 2.5 up to 4.5kPa CO2 for ‘McIntosh’). Overall, 1-MCP reduced internal ethylene production, and improved firmness and acidity retention in all apple cultivars. The addition of a second 1-MCP treatment after 4 months of CA storage further improved firmness retention in ‘McIntosh’ and late harvested ‘Empire’ apples after 7d at room temperature. ‘Northern Spy’ apples treated with 1-MCP had lower incidence of external CO2 injury, regardless of 1-MCP treatment timing. Multiple 1-MCP treatments had varying effects on the incidence of core browning; late-harvested ‘McIntosh’ treated twice with 1-MCP exhibited the highest incidence of core browning, while late-harvested ‘Empire’ treated twice had less core browning than those not treated. ‘Northern Spy’ treated only at harvest time had more core browning compared to those treated only or also after 4 months of CA storage and non-treated fruit. 1-MCP treatment had no significant effect on the incidence of internal browning in ‘McIntosh’ or ‘Empire’ apples. These results suggest that a second application of 1-MCP after 4 months of CA storage may improve firmness retention in some cultivars during holding at room temperature, but it can also have variable responses associated with susceptibility to disorders, especially when holding apples in long-term CA storage.

EFFECTS OF PREHARVEST AND POSTHARVEST 1-METHYLCYCLOPROPENE TREATMENT ON EXTERNAL CO2 INJURY IN APPLES DURING STORAGE

The objective of this study was to investigate the effects of preharvest and postharvest 1-methylcyclopropene (1-MCP) treatment on the incidence of external CO2 injury in apples during storage. During a period of 4 years, 'McIntosh' or 'Empire' trees were either untreated or sprayed 7 to 11 days before harvest with 1-MCP (Harvista). Following harvest, apples were cooled overnight and then treated within 7 days with or without 1-MCP (SmartFresh) for 24 hours at 3°C. Apples were subsequently held in controlled atmosphere (CA) at 3°C for 6 or 9-9½ months. Apples from trees sprayed with Harvista and/or treated with SmartFresh developed more external CO2 injury, compared to those not treated. The incidence was greatest in SmartFresh-treated fruit that had been sprayed with Harvista containing the highest 1-MCP concentration, while less CO2 injury developed when SmartFresh was applied closer to harvest. The usual 1-MCP effect of improved firmness retention was observed throughout.

Delayed controlled atmosphere storage affects storage disorders of ‘Empire’ apples

The objective of this study was to investigate the effect of delayed controlled atmosphere (CA) storage on the development of storage disorders in ‘Empire’ apples, in combination with postharvest 1-methylcyclopropene (1-MCP) treatment, to maintain fruit firmness during long-term storage. Over two consecutive seasons, ‘Empire’ fruit were cooled overnight and then treated with or without 1μLL−1 1-MCP for 24h at 3°C. Apples were subsequently held either in CA storage (2.5kPa O2+2.0kPa CO2) at 3°C for 9 months or in ambient air at 1°C for 1 or 2 months and then CA storage at 3°C for 8 or 7 months (delayed CA), respectively. 1-MCP-treated apples with a 2-month delay in CA establishment had less external CO2 injury and flesh browning during both years of study. Delayed CA for 1 month also reduced external CO2 injury incidence, similar to the 2-month delay. Delayed CA did not affect core browning incidence in 1-MCP-treated fruit, although a 2-month delay in CA reduced core browning in apples without 1-MCP. 1-MCP improved firmness retention of ‘Empire’ apples during long-term CA storage, even when CA establishment was delayed. Fruit not treated with 1-MCP were always softer with delayed CA storage. There was little effect of delayed CA on internal ethylene, soluble solids, or titratable acidity. Overall, the results suggest that delaying CA storage to reduce the development of certain storage disorders in ‘Empire’ apples could be utilized in combination with 1-MCP treatment to retard fruit softening during long-term storage. This may be an acceptable compromise for reducing fruit losses due to storage disorders while maintaining acceptable firmness for the marketplace.

Storage Life and Deterioration of Intact Cantaloupe (Cucumis melo L. var. reticulatus) Fruit Treated with 1-Methylcyclopropene and Fresh-cut Cantaloupe Prepared from Fruit Treated with 1-Methylcyclopropene Before Processing

A study was conducted to determine the influence of the ethylene action inhibitor, 1-methylcyclopropene (1-MCP), on the shelf life and deterioration during storage at 5 °C of intact netted muskmelon (Cucumis melo L. var. reticulatus) fruit and fresh-cut cubes prepared from those fruit. ‘Durango’, ‘Magellan’, and ‘7920’ fruit (3/4 to full-slip stage) were treated with 1-MCP (1.0 μL·L−1) for 24 h at 20 °C. Preliminary research with ‘Athena’ muskmelon had shown that the more physiologically advanced distal pericarp tissue developed significantly more watersoaking than the less advanced proximal and center portions during 5 °C storage; therefore, after treatment with 1-MCP and cooling to 5 °C, the center portions of the fruit were used to prepare the fresh-cut samples. Fresh-cut cubes and intact fruit were stored for 12 d at 5 °C. Intact fruit of all tested cultivars responded to 1-MCP application with improved firmness retention during storage, but no watersoaking was observed in intact fruit. The effect of 1-MCP treatment on the firmness retention and watersoaking of fresh-cut cubes from the different cultivars was inconsistent. Exposure of muskmelon fruit to 1-MCP did not significantly influence the flesh color or soluble solid contents of either intact fruit or fresh-cut cubes during storage at 5 °C.

Effect of Processing Under Ultraviolet Light on the Shelf Life of Fresh-Cut Cantaloupe Melon

ABSTRACT: The effect of processing cantaloupe melon under ultraviolet-C (UV-C) radiation on storage properties of the cut fruit at 10 °C was compared with post-cut UV-C fruit treatment and the untreated control. Cutting fruit under UV-C light induced a hypersensitive defense response that resulted in increased accumulation of ascorbate peroxidase relative to the other 2 treatments. Fruit processed under UV-C radiation had the lowest esterase activity throughout the storage period. Lipase activity was higher in post-cut treated fruit than fruit processed under UV-C light and the control fruit. Lipase activity, however, decreased rapidly in fruit processed under UV-C and was undetectable after 7 d of storage. Human sensory aroma evaluation indicates reduced rancidity, and instrumental texture measurements suggested improved firmness retention in fruit cut under UV-C radiation. The treatment also reduced respiration during cut fruit storage. UV-C was effective in reducing yeast, mold, and Pseudomonas spp populations in both treatments. Fresh-cut pieces from whole melon cut under UV light had lower populations of aerobic mesophilic and lactic acid bacteria relative to the control and post-cut treated pieces. Results indicate that while post-cut application of UV improved shelf life of cut cantaloupe melon, cutting fruit under UV-C radiation further improves product quality.

Factors Influencing texture retention of salt-free, acidified, red bell peppers during storage.

Red bell peppers were stored in a salt-free, acidified cover solution with sulfite as a microbial preservative. The texture retention of stored peppers was evaluated as a function of pH, acid, calcium, blanch treatment, and growing conditions of the peppers. Field-grown peppers softened at a faster rate than greenhouse-grown peppers and exhibited more variability in their ability to maintain texture during storage. Improved firmness retention of red peppers stored at 30 degrees C was observed when the pH was adjusted to be in the range of 3.4-3.8, when at least 5 mM calcium was added to the peppers, and when red peppers were blanched at 75 degrees C for at least 1 min.

Influence of temperature and duration of 1-methylcyclopropene (1-MCP) treatment on apple quality

Abstract The objectives of this study were to determine the efficacy of 1-MCP treatments at various temperatures and durations, and to evaluate the effects of 1-MCP on ‘Cortland’ and ‘Empire’ apple quality after storage. Fruit were exposed to 0.6 μl l−1 of 1-MCP for 0, 3, 6, 9, 12, 16, 24, or 48 h at 3, 13, or 23 °C. Following treatment, fruit were stored in ambient air at 0–1 °C for 120 days and then held at 20 °C for 7 days. ‘Cortland’ apples treated with 1-MCP at 3 °C showed improved firmness retention (>63.0 N) with at least 9 h of treatment, whereas those treated at either 13 or 23 °C showed improved firmness retention with at least 6 h of treatment. ‘Empire’ apples treated with 1-MCP showed improved firmness retention (>67.5 N) with only 3 h of treatment regardless of temperature, but those treated at 3 °C for 3 h no longer had the full firmness advantage after an additional 7 days at 20 °C. There was no significant effect of 1-MCP on soluble solids concentration. Treatment with 1-MCP for 3 h at any of the temperatures significantly reduced the incidence of superficial scald in ‘Cortland’ apples. Overall, the results indicate that 1-MCP has tremendous potential for maintaining apple quality during storage, but its efficacy can be affected by treatment temperature and duration as well as by apple cultivar.

The effect of preharvest foliar sprays of calcium on quality and shelf life of two cultivars of sweet bell peppers (Capsicum annuum L.) grown in plasticulture

The effect of preharvest calcium sprays on postharvest quality of sweet bell peppers grown in plasticulture was studied. Calcium was applied as three sprays of 0.4% (wt/vol) CaCl2 in water to plots of Oriole and Bell Boy peppers in each of 2 yr. Fruit weight, water loss, firmness, decay and the composition of the pectic fractions were determined at harvest and during storage. Preharvest sprays of CaCl2 increased the weight of fruit for Oriole, improved firmness retention in storage, decreased decay, increased pericarp wall thickness and the insoluble pectic fractions of both cultivars but had no effect on water loss in storage. The results suggest that Ca improves firmness retention through enhancing the pectic composition of cell walls and pericarp wall thickness. Effects of Ca sprays on reducing decay could not be attributed to factors measured in this work. Preharvest foliar sprays of CaCl2 show promise in reducing postharvest decay and improving firmness retention in sweet bell peppers grown under plasticulture. Key words: Capsicum annuum L., calcium, pectin, shelf life, postharvest decay

Firmness Retention in Pickled Peppers as Affected by Calcium Chloride, Acetic Acid, and Pasteurization

ABSTRACTCritical factors influencing firmness retention in pickled peppers were studied. The addition of CaCl, (0.2%, w/v, optimum) to whole, pickled‘Red Cherry’peppers increased firmness retention as determined by a puncture test using an Instron Universal Testing Machine. Pasteurization reduced firmness in the absence, but not in the presence, of added CaCl2. CaCl2 significantly (P ≤0.01) reduced softening during storage of‘Red Cherry’peppers at higher temperatures (36.7, 46.7°C), and resulted in a slight increase in firmness at 26.7°C. CaCI2 did not significantly (P≥ 0.05) improve firmness retention in‘Jala‐peno’peppers, but resulted in greater uniformity of firmness. CaCI, also improved firmness retention in pickled cucumbers. Firmness of unpasteurized peppers and cucumbers was not influenced significantly (P ≥0.05) by acetic acid concentrations of 2, 3 or 4%.

The effects of high carbon dioxide pre-treatments and ethylene removal on the storage performance of apples ‘Cox's Orange Pippin’

High CO 2 treatment immediately after harvest combined with ethylene removal improved the instrumental and sensory firmness of apples cultivar ‘Cox's Orange Pippin’ following storage in 1.25% O 2. There was no residual effect of these treatments after storage. A single treatment with 15% CO 2 for the first 15 days after harvest was as effective as when repeated for 7 days after 8 weeks of storage; each of these regimes was as effective as a single treatment with 30% CO 2 for the first 30 days. Without ethylene removal, pre-storage treatment with 15% CO 2 resulted in improved firmness retention as assessed by a sensory panel, but not as determined by a penetrometer. In both years of these experiments, high CO 2 pre-treatments increased the risk of lowtemperature breakdown; overall sensory acceptability was either reduced or unaffected by high CO 2 treatments.

EFFECTS OF PHOSPHATE SPRAYS ON McINTOSH APPLE FRUIT AND LEAF COMPOSITION, FLESH FIRMNESS AND SUSCEPTIBILITY TO LOW-TEMPERATURE DISORDERS

Phosphate compounds (NH4H2PO4, KH2PO4 and CaH4(PO4)2 in 1982; NH4H2PO4 in 1983) applied to McIntosh apple trees as six foliar sprays at weekly intervals starting 4 wk after bloom, increased leaf and fruit P, decreased loss of firmness under some storage conditions and decreased incidence of low-temperature storage disorders. Phosphate sprays improved firmness retention of apples stored in either 5% CO2 plus 3% O2 or 0.7% CO2 plus 1% O2 in 1982 and maintained fruit firmness during a simulated shelf life at 20 °C for apples stored at 0 °C. Firmness retention at 20 °C of the 1983 crop was improved by monobasic ammonium phosphate regardless of storage temperature. Apple samples from unsprayed control trees had mean phosphorus concentrations of 85.4 and 94.4 ppm fresh weight in 1982 and 1983, respectively (whole fruit less seeds and stems).Key words: Apple, fruit phosphorus, low temperature breakdown, core flush