Fernando Riquelme

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.

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.

Effects of foliar sprays containing calcium, magnesium and titanium on plum (Prunus domesticaL.) fruit quality

An experiment was performed in which Ti(4+)-ascorbate was sprayed onto plum trees in several combinations with other commercial compounds containing Ca2+ and Mg2+ to study the effects on the commercial quality of fruits, with special focus on improving their resistance against postharvest handling damage. All the treatments containing titanium increased the tree performance (branch elongation, flowering and fruit setting intensities) and fruit size. At harvest fruits from the Ti-treated trees showed improved resistance to compression and penetration, as well as a decrease in weight-loss during postharvest storage. A similar response was obtained for the external colour, though all the treatments seemed to delay somewhat the apparent ripening status. Nevertheless, the fruits from Ti-treated trees showed a better behaviour in the evolution of the colour parameters during storage than did the control fruits. Titanium application significantly increased the calcium, iron, copper and zinc concentrations in peel and flesh. This improvement in the calcium absorption is explained as a consequence of the beneficial effect of titanium on the absorption, translocation and assimilation processes.

Pectic enzymes in fresh fruit processing: optimization of enzymic peeling of oranges

Abstract An enzymic technique for peeling oranges has been optimized. The process is based on the vacuum infusion of a commercial glycohydrolase preparation (pectinases and cellulases) (Rohament PC) allowing the removal of the orange peel to obtain peeled whole fruit and segments. The influence of the different parameters of the process, such as the vacuum conditions necessary for infusing the enzyme preparation, enzyme concentration, pH, temperature and enzyme solution reusability, have been studied. To improve the enzymes action, several cuts were made in the orange peel to facilitate the introduction of the enzyme solution, and substantial differences in peeling quality were obtained as a function of the different cutting patterns assayed. The optimal processing conditions for peeling whole oranges made it possible to reuse the enzyme solution for 8 days without any significant loss in enzyme activity or peeling efficiency. This is obviously of interest for any industrial application.

NON-INVOLVEMENT OF ACC AND ACC OXIDASE ACTIVITY IN PEPPER FRUIT RIPENING

Abstract Pepper of the variety California shows sigmoid-type growth curves and changes of colour, which are characteristic of the fruit reaching maturity, when it has practically reached full size. Respiratory activity is high a few days after fruit-set and then falls progressively. Ethylene production and 1-aminocyclopropane-1-carboxylic acid (ACC) levels remain low throughout fruit development and maturation, while ethylene-forming enzyme (EFE) activity gradually falls throughout the development. We show that treatment with propylene has no effect on the post-harvest maturation of pepper, although treatment with silver thiosulphate (STS) increases respiratory intensity and ethylene production due to the stress caused which, in turn, causes an increase in ACC levels after treatment. All these results lead to the conclusion that pepper behaves like a non-climacteric fruit during maturation, and that maturation is not regulated by ethylene.

Ethylene biosynthesis and physico-chemical changes during fruit ripening of cherimoya (Annona cherimola, Mill)

This work indicates that cherimoya behaves like a climacteric fruit after harvesting, because it shows respiration and ethylene crises connected with its ripening. The increase in ethylene production is caused by an increase in the activities of ACC-synthase and ethylene-forming enzyme (EFE), which are very low in the freshly picked fruit, but increase rapidly over the second day, reaching a maximum on the third day. During the climacteric there is also a low amount of 1-aminocyclopropane-l-carboxylic acid (ACC) in its conjugated form. Skin browning increases after harvesting, but this is not related to a decrease of chlorophyll, since the chlorophyll level remains stable throughout the entire post-harvest period. The level of browning shows a good correlation (r=0.947) with the L parameter of colour of reflection. There is a temporal coincidence between the onset of ethylene production, the degradation of starch, the loss of firmness and the build up of total sugars.

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

Levels of ACC and physical and chemical parameters in peach development

SummaryThe state of maturity of peach fruits (Prunus persica, L.) was determined in terms of different physical and chemical attributes at different stages of fruit development. It was shown that the onset of softening coincided with an increase in red fruit colour, 100 days after fruit set. At the same time the rates of respiration and ethylene production reached maxima of 210 mg CO2 kg−1 h−1 and 23 nl ethylene g−1 h−1, respectively. During the first 60 days of development the concentration of conjugate ACC was about 40 times higher than that of free ACC. A subsequent fall in conjugate and free ACC was succeeded by a rapid increase in both conjugate and free ACC at the time of onset of the respiration climacteric.

Review : Role of polyamines in chilling injury of fruit and vegetables/Revisión: El papel de las poliaminas en los daños por frío de frutas y hortalizas

Some tropical and subtropical fruit and vegetables suffer chilling injuries (CI) when exposed to low (above freezing) temperatures. The symptoms of such injuries vary between species, although they usually involve staining of the peel and internal browing, and are related to important modi fications at the cell membrane level. The polyamines putrescine, spermidine and spermine, have an antisenescent action because of their capacity to link with anionic compounds in the cell membrane and to capture free radicals, thus stabilizing the lipid bilayer and preventing membrane deterioration. This paper reviews the mechanism responsible for the physiological alterations produced by chilling, the role of polyamines and the quantitative changes they undergo in the affected tissues. Finally, it describes the possibility of using different treatments to reduce the negative effects of low temperatures and their influence on polyamine levels.

Effects of Calcium-Containing Foliar Sprays Combined with Titanium and Algae Extract on Plum Fruit Quality

Abstract An experiment was performed in which soluble calcium (Ca) was sprayed on plum trees in combinations with two bioactivators containing (Ti+4)-ascorbate and/or marine algae extract to study the effects on the commercial quality of fruits, with special attention paid to any increase in their resistance to postharvest handling damage. All the treatments containing titanium (Ti) increased tree development and fruit size. At harvest, fruits from the Ti-treated trees increased resistance to compression and penetration, but decreased weight-loss during postharvest storage. External red color was also improved and the color parameters remained more stable during storage as compared to the control fruits. Titanium application led to significant increases in the Ca, iron (Fe), copper (Cu), and zinc (Zn) concentrations in both peel and flesh. The improvement in Ca assimilation can be explained by the beneficial effect of Ti on absorption, translocation and assimilation processes.