Domingo Martínez-Romero

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).

The role of polyamines in the improvement of the shelf life of fruit

Abstract Polyamines are natural compounds involved in many growth and developmental processes with ubiquitous presence in all cells. Fruits have been the main plant organ in which a comprehensive research has been developed to get a better understanding of the role of polyamines, both endogenous and exogenous, especially during the ripening and senescence processes. The purpose of this review is to describe the latest advances about the relationship between polyamines and fruit ripening and post-harvest storage.

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.

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.

Effects of post-harvest putrescine and calcium treatments on reducing mechanical damage and polyamines and abscisic acid levels during lemon storage

The role of post-harvest putrescine and calcium (at 1 mM), exogenously applied during storage of lemon at 15 °C, in relation to fruit firmness (fruit deformation force) and peel resistance (puncture force) was investigated. Also, the levels of endogenous polyamines (putrescine, spermidine and spermine) and abscisic acid (ABA) and the colour development in mechanically damaged fruits (50 N) were studied. Fruits under putrescine and calcium treatments maintained higher firmness values and more resistance to peel rupture than control ones during storage. Treated lemons showed also less deformation when the compression force (50 N) to induce mechanical damage was applied. Treated and damaged fruits showed a decline in polyamine content while ABA and colour changed in parallel with maturation during storage. In damaged control fruits, an increase of spermine and ABA levels as a consequence of mechanical damage was observed. From the results reported, spermine and ABA could be considered physiological markers of mechanical stress. © 1999 Society of Chemical Industry

Methylarsonic and dimethylarsinic acids toxicity and total arsenic accumulation in edible bush beans, Phaseolus vulgaris

The main objective was to evaluate whether arsenic accumulated in the edible pods and seeds of Phaseolus vulgaris, cv. F15 above the Spanish maximum recommended concentration for food crops, 1 mg kg−1 on a fresh weight basis. Only organic arsenicals, methylarsonic and dimethylarsinic acids were used because they were: (1) the only arsenic species allowed for agricultural applications and (2) more mobile than inorganic species. Selection of French beans, a sensitive plant to arsenic, was based on the fact that arsenic-upward translocation is higher in sensitive than in tolerant plants. A 2 x 3 factorial experiment was conducted with two organic arsenic species (methylarsonic acid, dimethylarsinic acid) and three arsenic concentrations (0.2, 0.5, 1.0 mg l-1). Experimental results showed that the low bean plant tolerance to arsenic was possibly due to the high arsenic-upward transport to shoots, which could result in profound negative metabolic consequences. Even under extreme adverse conditions, arsenic residues in edible beans were below the maximum statutory limit set by the Spanish legislation. It is concluded that the major drawback of organic arsenical herbicides is that of decreased productivity rather than high arsenic intake by consumers of edible products from sensitive plant species.