Daniel Valero

Postharvest biology and technology for preserving fruit quality.

Introduction and Overview Fruit Ripening Introduction Fruit Growth Fruit Ripening and Related Parameters Changes in Fruit Quality Attributes During Handling, Processing, and Storage Introduction What is Quality? Weight Loss Appearance Texture Flavor, Taste, and Aroma Bioactive Compounds Decay Mechanical Damage versus Fruit Quality Cold Storage and Fruit Quality Introduction Effect of Low Temperature Storage on Fruit Metabolism Cooling Rates Precooling Techniques Chilling Injury Heat Treatments Introduction Means of Heat Application Heat Treatments and Fruit Quality Storability Limitations: Heat Damage Calcium Treatments Introduction Calcium Sources and Pre- and Postharvest Methods for Application Pre- and Postharvest Calcium Treatments and Calcium Fruit Content Effect of Preharvest Treatment on Fruit Size Calcium Treatments and Fruit Firmness Calcium Treatments and Color, Soluble Solids, and Total Acidity Calcium Treatment and Bioactive Compounds Calcium Treatment, Cell Membrane Stability, and CI Reduction Effects of Calcium Treatment on Postharvest Decay Calcium Treatment and Ethylene Production and Respiration Rate Undesirable Effects of Calcium Treatments Polyamine Treatments Introduction Polyamine Biosynthesis and Regulation in Plant Tissues Polyamine and Human Diet Polyamine and Fruit Development Preharvest Polyamine Application and Fruit Ripening Postharvest Polyamine Application and Fruit Quality Polyamines and Chilling Injury Polyamines and Mechanical Damage Future Trends 1-Methylcyclopropene Treatments Introduction 1-MCP as Blocking Ethylene Receptors Postharvest 1-MCP Application 1-MCP in Nonclimacteric Fruits Preharvest 1-MCP Application 1-MCP on Physiological and Pathological Disorders Storage in Modified Atmosphere Packaging Introduction Films used in MA Packaging Generation of the Steady-State or Equilibrium Atmosphere Optimal CO2 and O2 Concentration Importance of Temperature Stability MAP and Fruit Quality Maintenance MAP Benefits for Storage of Fresh-Cut Fruits and Vegetables Future Research Needs Active Packaging Introduction Active Packaging Technologies Ethylene Adsorbers Antimicrobial Fruit Packaging Edible Coatings Future Trends Emerging Technologies Introduction Atmospheres with High O2 Biological Control UV-Irradiation References

Tools to Maintain Postharvest Fruit and Vegetable Quality through the Inhibition of Ethylene Action: A Review

Ethylene is a plant hormone controlling a wide range of physiological processes in plants. During postharvest storage of fruit and vegetables ethylene can induce negative effects including senescence, over-ripening, accelerated quality loss, increased fruit pathogen susceptibility, and physiological disorders, among others. Apart from the endogenous ethylene production by plant tissues, external sources of ethylene (e.g. engine exhausts, pollutants, plant, and fungi metabolism) occur along the food chain, in packages, storage chambers, during transportation, and in domestic refrigerators. Thus, it is a great goal in postharvest to avoid ethylene action. This review focuses on tools which may be used to inhibit ethylene biosynthesis/action or to remove ethylene surrounding commodities in order to avoid its detrimental effects on fruit and vegetable quality. As inhibitors of ethylene biosynthesis and action, good results have been found with polyamines and 1-methylcyclopropene (1-MCP) in terms of maintenance of fruit and vegetable quality and extension of postharvest shelf-life. As ethylene scavengers, the best results can be achieved by adsorbers combined with catalysts, either chemical or biological (biofilters).

Maturity stage at harvest determines the fruit quality and antioxidant potential after storage of sweet cherry cultivars.

Eleven sweet cherry cultivars were harvested at three maturity stages (S1 to S3) based on skin color and stored at 2 degrees C for 16 days and a further period of 2 days at 20 degrees C (shelf life, SL) to analyze quality (color, total soluble solids, and total acidity) and bioactive compounds (total phenolics and anthocyanins) and their relationship to total antioxidant activity (TAA), determined in hydrophilic (H-TAA) or lipophilic (L-TAA) fraction. For all cultivars and maturity stages, the ripening process advanced during postharvest storage with increases in color intensity and decreases in acidity, as well as enhancements in phenolics, anthocyanins, and TAA in both H-TAA and L-TAA, although important differences existed among cultivars. The results showed that sweet cherry should be harvested at stage S3 (4 days later than the commercial harvest date) since after 16 days of cold storage + SL, the highest antioxidant capacity was achieved for both H-TAA and L-TAA.

THE EFFECTS OF ESSENTIAL OILS CARVACROL AND THYMOL ON GROWTH OF PENICILLIUM DIGITATUM AND P. ITALICUM INVOLVED IN LEMON DECAY

In this work the antifungal efficacy of thymol, carvacrol and the mixture of both pure essential oils has been proved against Penicillium digitatum and Penicillium italicum, by using in vitro (liquid media, PDA plates and disk growth) and in vivo (lemon) tests. Results indicated that both essential oils were effective in inhibiting fungal growth in all in vitro tests, with the highest efficacy displayed by thymol. In addition, the application of wax with thymol and carvacrol to lemons inoculated with P. digitatum demonstrated the reduction of decay (expressed as percentage of infected fruit surface) in a concentration dependent manner, as well as reduced respiration rate, ethylene production and total acidity losses. Thus, the application of these essential oils together with wax in the citrus packing lines could be considered as good alternatives to reduce the use of synthetic fungicides.

Role of polyamines in extending shelf life and the reduction of mechanical damage during plum (Prunus salicina Lindl.) storage

Abstract The role of putrescine was investigated, exogenously applied during postharvest storage of mechanically damaged (50 N force) plums, (Prunus salicina Lindl., cv. BlackStar) at 10 °C, in relation to fruit firmness (force–deformation ratio and fruit flesh deformation) and ethylene and CO2 production rates. The metabolism of endogenous polyamines (free, conjugated-soluble, and cell wall-bound was also studied. Infiltration of putrescine led to a reduction in mechanical damage, and an increase in firmness of both force–deformation ratio and fruit flesh firmness parameters. Exogenous putrescine inhibited and delayed ethylene and CO2 production rates. The analysis of polyamine metabolism revealed an activation of the polyamine biosynthesis pathway, showing an accumulation of cell wall putrescine and spermidine, which are possibly responsible for the greater firmness of putrescine-treated plums compared with controls. In these treated fruit, the increase in free spermidine levels could be acting as a physiological marker of mechanical damage.

Sensory, Nutritive and Functional Properties of Sweet Cherry as Affected by Cultivar and Ripening Stage

In this article 11 commercial sweet cherry cultivars were selected to evaluate sensory, nutritive and functional properties over the maturation process on tree. Fruit quality was significantly different among cultivars and maturity stages at harvest, with the highest quality scores being found in the harvest which was 4 days beyond current commercial harvest maturity for all the cultivars tested. Taking into account all of the measured parameters (weight, firmness, color, acidity and total soluble solids), ‘NY-6479’, ‘Prime Giant’ and ‘Sunburst’ could be classified as having the highest quality in terms of sensory attributes. However, ‘Cristalina’ and ‘Sonata’ had the highest functional quality, as determined by the measurement of bioactive compound content and antioxidant capacity. We conclude that a delay of a few days in harvesting of sweet cherries would lead to achieve maximal nutritional (highest sugar and organic acid contents), sensory (greatest firmness and color development) and functional (greatest phenolics content, anthocyanins and antioxidant capacity) quality to provide both eating enjoyment and health benefits to the consumer.

Prestorage oxalic acid treatment maintained visual quality, bioactive compounds, and antioxidant potential of pomegranate after long-term storage at 2°C.

Oxalic acid at three concentrations (2, 4, and 6 mM) was applied by dipping to pomegranate fruits of cv. Mollar de Elche, which were then stored for 84 days at 2 degrees C. Pomegranate is a chilling-sensitive fruit and, thus, control fruits exhibited chilling injury (CI) symptoms after long-term storage at 2 degrees C that were accompanied by increased respiration rate, weight loss, and electrolyte leakage (EL). The CI symptoms were significantly reduced by oxalic acid treatment, especially for the 6 mM concentration. In addition, control pomegranates showed significant reduction in the content of total phenolics and ascorbic acid as well as in total antioxidant activity (TAA), in both hydrophilic (H-TAA) and lipophilic (L-TAA) fractions. The application of oxalic acid led to lower losses of total phenolics and significant increase in both ascorbic acid content and H-TAA, whereas L-TAA remained unaffected. Thus, oxalic acid could be a promising postharvest treatment to alleviate CI and increase antioxidant potential.

Comparative Study of Two Plum (Prunus salicina Lindl.) Cultivars during Growth and Ripening

Some physicochemical parameters related to fruit growth and ripening, as well as the plant growth regulators ethylene, abscisic acid and polyamines were determined in two plum cultivars (Golden Japan and Santa Rosa) during their development and ripening. From the ninth week of development, the physicochemical parameters (punction force, color and ripening index) showed significant modifications, indicating that the ripening process had begun. Santa Rosa cultivar exhibited a climacteric ripening pattern, in which these changes coincided with increase in respiration rate, ethylene emission and l-aminocyclopropane-l-carboxylic acid (free and total) content, while Golden Japan cultivar showed a non-climacteric ripening process, without any increase in ethylene or respiration rate associated with ripening. Polyamines increased in Golden Japan cultivar during ripening (especially putrescine), which could be responsible for the low ethylene emission. In both cultivars, abscisic acid started to increase, coinciding with the changes in the parameters related to ripening.

Physiological changes in pepino (Solanum muricatum Ait.) fruit stored at chilling and non-chilling temperatures

The sensitivity of pepino (Solanum muricatum Ait. cv. Sweet Long) fruit to chilling injury (CI) as well as some physiological implications were studied. Three ripening stages (from immature to ripe) were used: green (G), light-green (LG) and yellowish-green (YG), and three storage temperatures were evaluated: 20, 10 and 1 °C. CI symptoms appeared with increasing storage time, the more severe being found in fruit harvested at more advanced ripening stages. In YG pepinos, increases in weight losses, ethylene production, respiration rate and 1-aminocyclopropane-1-carboxylic acid (ACC) levels, as well as decreases in fruit firmness and Hue angle were observed during storage at 1 °C. These changes could be considered as cold-induced. Free, conjugated-soluble and cell wall-bound putrescine (Put) showed significant increases in YG pepinos stored at the CI temperature compared with levels in fruit stored at 10 and 20 °C. This general increase in Put levels might be a response mechanism against this stress.

Postharvest biology and technology of pomegranate

Pomegranate is a subtropical and tropical fruit of great importance from a health point of view. Despite increasing consumer awareness of the health benefits of pomegranate, consumption of the fruit is still limited owing to poor postharvest handling, storage recommendations, short shelf life and quality deterioration during transportation, storage and marketing. The occurrence of physiological disorders such as husk scald, splitting and chilling injury is another challenge reducing marketability and consumer acceptance. Recently, notable work on postharvest biology and technology has been done. Pomegranate is highly sensitive to low-oxygen (<5 kPa) atmospheres, chilling injury and decay. One of the major problems associated with pomegranate fruit is excessive weight loss, which may result in hardening of the husk and browning of the rind and arils. To reduce chilling injury incidence and to extend storability and marketing of pomegranates, good results were obtained with polyamine, heat, salicylic acid, methyl jasmonate or methyl salicylate treatments prior to cold storage. This article reviews the maturity indices, changes during maturation and ripening, postharvest physiology and technology of pomegranate fruit as well as the various postharvest treatments for maintaining fruit quality.