Browning Inhibition in Fresh-Cut Pears

Treatments to control browning and maintain quality of fresh-cut pears were evaluated. Pear wedges were dipped in solutions containing sodium erythorbate, CaCl₂ and 4-hexylresorcinol; packed in air or with a modified atmosphere (MAP); and stored at 4°C. Samples were evaluated for browning, microbial spoilage, and presence of off-flavors or loss of firmness. For treatments to be successful, pears had to be above a minimum firmness of 4 kg (d'Anjou) or 5 kg (Bartlett) when treated. Inhibitor treatments, in conjunction with MAP, controlled browning and maintained quality of fresh-cut Bartlett and d'Anjou (but not Bosc pears) for 12–14 days.     

The response of unripe Conference pears to modified atmosphere retail packaging

Unripe green Conference pears with initial firmness values of 46–55 N were sealed in modified atmosphere (MA) low density polyethylene (LDPE, 30μ) pillow packs and in perforated control packs on three dates during 1985–1986. Changes in pack atmosphere composition, skin chlorophyll content, flesh firmness and sensory quality were monitored during 14–20 days simulated shelf-life at 20°C. In MA packs, equilibrated atmospheres containing 5–9% CO₂ and < 5% O₂ developed within c. 3 days. Chlorophyll degradation was completely inhibited by MA and resumed when packs were perforated, but MA only partially retarded the rate of flesh softening. Variations in the rate of ripening changes in duplicate MA packs could not be explained simply by differences in pack atmospheres. Furthermore, pears retarded by MA packaging failed to develop the normal sweet, aromatic flavour and succulent, juicy texture of 'eating-ripe' fruit, even when the packs were perforated after 4 days.
The differences in the responses of pears and apples to MA packaging, and the limitations of using this technique for the commercial marketing of English pears are discussed.     

Quality changes in fresh-cut Fuji apple as affected by ripeness stage, antibrowning agents, and storage atmosphere

ABSTRACT:  The effect of ripening state, modified atmosphere, and the use of antibrowning agents was investigated in an attempt to determine optimum ripeness and processing conditions for extending the shelf-life of fresh-cut Fuji apple. Apples were classified in 3 groups: mature-green, partially ripe, and ripe; after peeling and slicing, fruits were treated with 1% (w/v) N -acetylcysteine, or 1% (w/v) ascorbic acid (control), and then packed into polypropylene trays with air or a gas mixture (2.5% O₂+ 7% CO₂+ 90.5% N₂) and sealed. Trays containing the apple slices were stored in darkness at 4 °C ± 1 °C and analyzed periodically during 43 d. Changes in atmosphere composition, color, and firmness were examined. Partially ripe apples, based on their lower ethanol production and maintenance of their original color and firmness, were the most suitable to prepare the fresh-cut commodities. A postcutting dip in 1% (w/v) N -acetylcysteine was the most effective treatment to prevent cut surface browning and preserve the initial appearance of Fuji apple slices during more than 1 mo at 4 °C. Low O₂ and elevated CO₂ (2.5% O₂+ 7% CO₂) atmosphere extended the shelf life of apple slices because of a significant inhibition of ethylene production.     

Physicochemical, Microbiological, and Sensory Evaluation of Minimally Processed Tarocco Clone Oranges Packaged with 3 Different Permeability Films

ABSTRACT: Fruits of 3 Tarocco clones ('Gallo', 'Arcimusa', and 'Scirè') were sliced, packaged with different permeability films, and stored at 4°C for 14 to 15 d to find the best clone for processing and the most suitable packaging conditions to extend the shelf life of these products. Physicochemical parameters of Tarocco oranges slices, packaged with 3 films of different permeability, did not show marked decay phenomena during the storage days. Only a reduction in the ascorbic acid content was observed in almost all the examined clones, especially in products packaged with the most O₂ permeable films. Concerning microbiological contamination, all clones, packaged with the 3 films, showed, until the 12th storage day, a lower number of colony forming units (CFU)/g (≤ 3.6 × 10⁷ CFU/g) for mesophilic viable counts than the 2 microbiological criteria generally used for fresh-cut fruit and vegetables (10⁸ CFU/g for mesophilic viable counts). In fact, for these products it is possible to expect a shelf life longer than 12 to 13 d. Regarding sensory results, it was observed that the minimally processed Tarocco clone slices packaged with the most permeable to O₂ film were the most appreciated.     

Retaining Green Pigments on Thermally Processed Peels-on Green Pears

ABSTRACT: The interest in developing peels-on thermally processed (canned) green pears has prompted the investigation of retaining green pigments during thermal processes. Use of zinc ions as a processing aid for the retention of green pigment and surface pretreatment to remove waxy layer and a part of the top cuticle layer of the peels for enhancing reactions of zinc ions with chlorophylls in peel tissues were studied. Whole pears or pear chunks were subjected to zinc treatment during presoaking in 5200 ppm Zn²⁺ solutions for 60 min or blanching at 94 °C for 6, 12, and 18 min in a 1300, 2600, or 5200 ppm Zn²⁺ solution for identifying the most appropriate procedures for retaining green peel pigments. Pears were then thermally processed in glass jars at 94 °C for 20 min after commercial canning. Canned pears were subjected to an accelerated shelf life test in rooms set at 10 °C, 21 °C, and 38 °C under fluorescent light. CIELAB L *, a *, and b * color values of pear samples were monitored during storage up to 35 wk. Results showed that surface pretreatment is essential for ensuring the reactions of zinc ions with green pigments, thus retaining green pigment during thermal treatment. Blanching pears in zinc solution containing about 1300 ppm Zn²⁺ was effective in obtaining attractive green-colored canned pears. Hue angle and - a * (greenness) values of canned pears were significantly ( P < 0.05) associated with blanching time and zinc concentration in blanching solutions, and remained stable over 19 wk of storage under intensive illumination at all 3 temperatures. The technology used zinc ions as a processing aid, thus significantly minimizing the zinc content in the final processed pears.     

Maintaining Quality of Fresh-cut Tomato Slices through Modified Atmosphere Packaging and Low Temperature Storage

ABSTRACT: Quality of fresh-cut tomato slices was compared during cold storage under various modified atmosphere packaging conditions. Chilling injury of slices in containers sealed with Film A was higher than with Film B; these films had oxygen transmission rates of 87.4 and 60.0 ml · h^-1· m^-2· atm^-1 at 5 °C and 99% RH, respectively. While slices in containers with an initial atmospheric composition of air, 4% CO₂+ 1 or 20% O₂, 8% CO₂+ 1 or 20% O₂, or 12% CO₂+ 20% O₂ showed fungal growth, slices in containers with 12% CO₂+ 1% O₂ did not. Low ethylene in containers enhanced chilling injury. Modified atmosphere packaging provided good quality tomato slices with a shelf life of 2 w or more at 5 °C.     

Physical Properties, Sensory Attributes, and Consumer Preference of Pear Fruit Leather

ABSTRACT: Pear fruit leathers were prepared by drying a mixture of pear juice concentrate, pectin, corn syrup, and water at 70°C for 8 h. The effects of ingredients on texture, color, microbial growth, moisture content (MC), water activity (a_w), glass transition temperature (T_g), and sensory attributes were investigated. Pectin was the most significant independent variable that affected the properties of interest. This was followed by initial moisture content and corn syrup. Glass transition temperature (T_g) was not useful for predicting microbiological attributes but had strong correlations with instrumental and sensory hardness and chewiness. The results from partial least squares analysis (PLS) indicate instrumental hardness, chewiness, and cohesiveness could be used to predict their corresponding sensory attributes. The consumer liking of pear fruit leather could be increased by raising their fruit aroma, sweetness, tartness, and shininess.     

Effect of controlled atmospheres on maintaining quality of persimmon fruit cv. "Rojo Brillante"

ABSTRACT:  Astringent "Rojo Brillante" persimmon fruits were stored in air or in 2 different controlled atmospheres: 10% CO₂+ 90% N₂ (CA1) or 97 % N₂+ air (CA2) for up 50 d at 15 °C. After different periods, the fruit were treated with 95% CO₂ for 24 h at 20 °C in order to remove astringency, and then transferred to 20 °C in air free of CO₂ for 5 d to simulate shelf life. Other fruits were directly transferred to shelf life without being submitted to deastringency treatment. Storage under CA2 allowed storability of persimmon "Rojo Brillante" during 30 d at 15 °C, maintaining commercial firmness. Moreover, CA2 had an effect on removing astringency when fruits were stored for 30 d at 15 °C, or after 20 d following to shelf life. As consequence, deastringency treatment could be avoided when the fruits were previously stored under this controlled atmosphere.     

Effects of Ripeness Stages on the Storage Atmosphere, Color, and Textural Properties of Minimally Processed Apple Slices

ABSTRACT: Fruit maturity is a determinative factor in maintaining the original color and, to a greater extent, the texture of minimally processed fresh-cut apple slices. Mature-green apples (because of their lower respiration and ethanol formation) were the most suitable to process for extending post-cutting-quality shelf life. Sliced apples processed at an earlier stage of ripeness, but dipped in a solution of ascorbic acid (C₆H₈O₆) and calcium chloride (CaCl₂) and stored under 100% N₂, preserved their original color with minor changes. However, these processing and packaging treatments could not effectively prevent the apple slices from softening, and apple flesh underwent a progressive loss of firmness from 8.0 to 4.8 N.     

1-MCP缓释处理对气调贮藏后的‘安久’梨货架期品质的影响

以‘安久’梨为试材,利用3% 1-甲基环丙烯（1-MCP）缓释剂处理在2.2% O₂下贮藏6个月后的两个果园梨果实,研究1-MCP缓释处理对梨果实出库后在冷藏（模拟运输过程）和货架期中果实生理病害发生、乙烯释放率、硬度、果皮叶绿素、可溶性固形物和可滴定酸的影响,为今后其商业标准化应用提供理论依据。结果表明:与对照组果实相比,1-MCP缓释处理能降低货架期果实腐烂率和虎皮病发病率,降低α-法尼烯含量和共轭三烯积累。此外,1-MCP缓释处理能抑制果实乙烯释放,延缓果实硬度下降,果皮叶绿素和可滴定酸降解,但对可溶性固形物含量无影响。1-MCP处理的Lot 375果园（海拔为114.30 m）梨果实在经冷藏10 d后第21 d货架期时果实硬度降至24.76 N并伴随乙烯逐渐上升,而1-MCP处理的Lot 39果园（海拔为10.06 m）梨果实果实硬度为39.14 N,此时乙烯仍维持在较低的水平。因此,在人工短缺时,晚采收的高海拔地区果园‘安久’梨可先进行气调贮藏,待出库、清洗、分拣、包装处理后加入缓释型1-MCP,可降低货架期果实生理病害发生,保持较高的果实品质,但不影响果实软化。     

Composition, sensory quality and respiration during ripening and storage of edible wild mango (Irvingia gabonensis)

The effects of tree and room ripening and of storage at chill temperatures and at 26–29°C on the sensory quality, composition and respiration of edible wild mango fruits were investigated.
Fruits harvested at the mature green stage and ripened at 26–29°C were slightly preferred to tree-ripened fruits in colour and texture. Apart from a lower moisture content, room-ripened fruits were comparable in composition with tree-ripened fruits. During storage at 26–29°C, CO₂ production increased sharply from 22 ml kg^-1 h^-1 at the end of the first day, reaching a maximum of 91 ml kg^-1 on day 5 and declining thereafter; O₂ consumption followed a similar trend. The respiratory climacteric coincided with the onset of ripening. Fruits held at 12–15°C developed symptoms of chilling injury including pitting and black spots in mature green fruits, and brownish discoloration, pitting, surface scald, excessive softening and decay in ripe fruits.     

Influence of Maturity at Processing on Quality Attributes of Fresh-cut Conference Pears

ABSTRACT: Influence of ripeness state of Conference pears on the respiration and quality changes of the minimally processed fruit was studied. The fruits processed at partially ripe maturity were the most suitable to obtain fresh-cut products. Slightly under-ripe pears exhibited less browning and firmness degradation. Treatments consisting of dips in 10 g/L ascorbic acid and 5 g/L calcium chloride and packaging in 15 cm^-2× m^-2× 24 day^-1× bar^-1 preserved the initial appearance of pear cubes for at least 14 d. Because of a significant inhibition of ethylene production, 0 kPa O₂ initial atmosphere was effective in preventing quality changes. Presence of ethanol, as a result of fermentative anaerobic processes, increased with ripeness, especially beyond the 1st 21 d of storage at 4 °C. On the contrary, acetaldehyde was less affected than ethanol by processing and storage conditions.     

Identification and Functional Characterization of Cysteine Protease from Nine Pear Cultivars (Pyrus pyrifolia)

This study was performed to compare the total protein and protease content among the whole fruit, flesh, and peel of nine different pear cultivars. Pear proteases were functionally characterized with respect to three enzyme assays. Proteases from pears were further identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, in gel activity staining, and matrix assisted laser desorption/ionization-time of flight mass spectrometry analysis. Flesh from Whasan, Nikita, and Hanareum cultivars contained relatively more total protein and protease and showed high enzyme activities, while Chuwhang contained the lowest amount of protein and protease activity. Protease content and enzyme activities found in the pear flesh or whole fruits were two to six times higher than those in the pear peel. Pear cultivars contained one or two protease bands with molecular weights of 36 kDa and/or 38k Da. The larger band was further identified as a cysteine proteinase with 70% homology to the pear cysteine protease from Pyrus pyrifolia.     

Retention of Fortified Vitamin E and Sensory Quality of Fresh-Cut Pears by Vacuum Impregnation With Honey

ABSTRACT:  Our hypothesis was that the incorporation of vitamin E into honey-based vacuum impregnation (VI) solution could be a novel approach to develop high-quality and vitamin E-fortified fresh-cut pears (D'Anjou). A 20% diluted wildflower honey VI solution was used with 0.4% to 0.8%α-tocopherol from 3 different sources: α-tocopherol-acetate (VE-acetate), free α-tocopherol (V-OH), or water-soluble α-tocopherol-acetate (VE-H₂O) for nutritional fortification of the pear slices. Fresh-cut pear slices were immersed in VI solution and subjected to a vacuum at 100 mm Hg for 15 min following atmospheric restoration for 30 min. Samples were stored at 2 °C and 88% relative humidity up to 2 wk for nutritional, physiochemical, and sensory quality evaluations. Vitamin E content of pears impregnated with honey solution containing VE-acetate, VE-OH, or VE- H₂O increased 80 to 100 times and 65% to 80% VE activities were retained during 2 wk storage. Microbial counts were under 2.6 log colony forming unit(CFU)/g pear at the end of 7 d storage, significantly lower than the industrial standard. Instrumental color analysis and sensory evaluation indicated that VE fortified pear slices had significantly higher lightness, lower browning index, and higher consumer acceptance rating than control (unfortified) ones. There is a strong Pearson correlation between instrumental analysis and consumer sensory evaluation in pear color. This study demonstrated a great potential for developing high-quality, vitamin E-fortified fresh-cut pears by use of VI technology with honey, thus further enhancing the health benefit of pears.     

Texture of rehydrated dried bell peppers modified by low-temperature blanching and calcium addition

Diced green bell pepper was blanched twice, once at 51–79 °C for 19–61 min, and once at 95 °C for 3 min, and dried. The firmness of rehydrated samples was measured by puncture, and optimum conditions assessed by response surface methodology. The optimized model showed that, blanching at 65 °C for 49 min gave a 64% increase in puncture force over the control. The optimum temperature was used to evaluate the effect of adding CaCl₂. The dices were blanched twice, once at 65 °C for 3 min in either 0 or 4% CaCl₂, secondly in either 0 or 2% CaCl₂ solution at 95 °C for 3 min. In the second case the dices had been held at room temperature for 0–30 min before treatment. Adding CaCl₂ increased puncture force significantly ( P  ≤ 0.05). The best results, those which gave greatest firmness, were obtained by blanching at 65 °C for 3 min in 4% CaCl₂, holding for 16 min after blanching, followed by a secondary blanching at 95 °C in 2% CaCl₂.     

High Vacuum Flame Sterilized Fruits: Storage Study on Sliced Clingstone Peaches, Sliced Bartlett Pears, and Diced Fruit

Slices of four major commercial clingstone peach varieties, slices of Bartlett pears from major growing areas, and mixtures of diced peaches and pears were successfully vacuum packed without the conventional covering syrup or water. For selected packs, the fruits were sweetened to the desired cutout °Brix value with concentrated syrup. The high vacuum flame sterilized packs (HVFS) required only 7.5 min total heating for pear and peach slices and 5.5 min for diced fruit to achieve biological stability. Because of the minimal process, all HVFS fruits retained more of the original flavor attributes and texture of the fresh fruit through 18 months storage than did the conventional packs. Omission of the covering liquid, combined with the necessary blanching treatment, allowed packing of 1/3 more fruit into a standard size can.     

RHEOLOGICAL INDICES OF FRUIT CONTENT IN JAMS: EFFECT OF FORMULATION ON FLOW PLASTICITY OF SHEARED STRAWBERRY AND PEACH JAMS

The effect of formulation factors on Casson yield values measured at low shear rates (0.08 ≤γ≤ 1.01s^-1) (σ₀₁) and at medium shear rates (2.58 ≤γ≤ 387.30s^-1) (σ₀₂) was analyzed in previously sheared strawberry and peach jams. Twenty three samples of each fruit jam were prepared according to a second order composite rotatable design. Composition ranges were: fruit content, 25–55%; soluble solids content, 60–70° Brix; added pectin in strawberry jams, 0.3–0.7% and in peach jams, 0.1–0.5%. Variation of σ₀₁ values in strawberry jams depended mainly on the interactions between fruit and soluble solids and between fruit and pectin, while in peach jams, it depended on fruit-soluble solids and soluble solids-pectin interactions. Patterns of change of σ₀₂ values with composition were similar to those observed for σ₀₁ in both strawberry and peach jams. Predictive power of σ₀₁ and σ₀₂ values for estimation of fruit content was low, but taken in conjunction with soluble solids content and total pectin values, 79.5% of the variability of fruit content in strawberry jams and 91.1% of same in peach jams could be explained.     

Effect of 1-Methylcyclopropene on Superficial Scald Associated with Ethylene Production, α-Farnesene Catabolism,and Antioxidant System of Over-Mature ‘d’Anjou’ Pears After Long-Term Storage

To optimize storage quality of ‘d’Anjou’ pears (Pyrus communis L.) produced in the US Pacific Northwest regions, the recommended harvest maturity as indicated by flesh pressure is 67 to 58 N. Over-mature pears are more susceptible to superficial scald and inferior eating quality after storage. However, a significant portion of pears is harvested at an over-mature stage due to rapid on-tree maturation during years with labor shortages. 1-Methylcyclopropene (1-MCP) extends storage quality of pears but interferes their ultimate ripening capacity. The purpose of this work was to evaluate the effect of 1-MCP on over-mature ‘d’Anjou’ pears. Fruit from two orchards at fruit firmness (FF) 55.6 and 56.0 N were treated with 0.15 μL L^?1 1-MCP, held at ??1.1 °C for up to 7 months. 1-MCP treatment significantly inhibited ethylene synthesis and respiration rate, reduced superficial scald, and maintained high storage quality of over-mature pears from two orchards during 7 months of storage. After 7 months of storage at ??1.1 °C, some of the pears from Orchard 1 recovered ripening capacity after 5 days at 20 °C. The development of superficial scald in over-mature ‘Anjou’ pears was associated with the accumulation of α-farnesene and conjugated trienols (CTols). 1-MCP significantly inhibited the development of scald, perhaps by alleviating membrane lipid peroxidation and enhancing total antioxidant capacity, antioxidant metabolites (i.e., total polyphenols (TP) and total flavonoids (TF)), and related enzyme activities (i.e., superoxide dismutase (SOD), catalase (CAT)) in pear skin. Overall, this study provides the preliminary basis for commercial application of 1-MCP in over-mature pears and demonstrates its potential to maintain fruit quality and reduce the incidence of superficial scald.     

Effect of Brining, Modified Atmosphere Packaging, and Superchilling on the Shelf Life of Cod (Gadus morhua) Loins

ABSTRACT:  The aim of these experiments was to evaluate the effect of brining, modified atmosphere packaging (MAP), and superchilling on the quality changes of cod loins as measured by microbial, sensory, and chemical analysis. Unbrined and brined (2.5 ± 1.0% NaCl) cod loins were kept in styrofoam boxes (air) and under modified atmosphere (MA, CO₂/O₂/N₂: 50/5/45) at 0, −2, and −3.6 °C. Samples were examined over a 4-wk period. Total viable psychrotrophic counts and counts of H₂S-producing bacteria reached higher numbers in the air-packed brined fish at −2 and −3.6 °C than in comparable unbrined groups, being significantly different ( P  < 0.05) at the lower temperature. However, lower counts of these bacteria were obtained in the brined MAP fish than in comparable unbrined fish. Counts of  Photobacterium phosphoreum  increased most rapidly in air- and MA-packed loins kept at 0 °C. Lower counts were found at superchilled temperatures. According to sensory analysis the shelf life of unbrined air-packed loins was about 11 d at 0 °C and 14 to 15 d at −2 °C. The shelf life of MA-packed unbrined loins was about 14 to 15 d at 0 °C but 21 d at −2 °C. Thus, synergism of combined superchilling (−2 °C) and MA led to a considerable shelf life increase for unbrined loins despite the fact that processing and packaging took place 4 to 5 d post-catch. The shelf life of air-packed brined loins at −2 °C was 12 to 15 d but only 13 d under MA. The same synergistic effect did therefore not apply to brined loins as with unbrined ones.     

Extending Shelf Life of Fresh-cut Pears

The effects of various treatments were evaluated for extending shelf-life of fresh-sliced pears. Sliced Anjou pears had browning-free color for 30 d by dipping with 1.0% ascorbic acid and 1.0% calcium lactate, but texture was soft with juice leakage. The combination treatment of 0.01% 4-hexylresorcinol (4-HR), 0.5% ascorbic acid and 1.0% calcium lactate can provide 15 to 30 d shelf-life for Anjou, Bartlett, and Bosc pears when the pears are sliced at an average ripeness of 43, 49, and 38 Newton respectively, with 2 min dipping, partial vacuum packaging, and 2 to 5 °C storage. 4-HR residual content ranged from 1 to 7 ppm after 14 d storage. Panelists could detect a flavor difference between 0.01% 4-HR treated pears and controls.