Normal Ripening Research Articles

Storage conditions and ripening of the custard apple Annona squamosa L.

Annona squamosa is a climateric fruit in which maximal carbon dioxide production preceeds that of ethylene during post-harvest storage. Normal ripening occurred at temperatures between 15 and 30° C, although the fruits were susceptible to fungal attack at temperatures above 25° C. Storage temperatures below 15° C caused chilling-injuries. Ripening was enhanced by removal of carbon dioxide and by addition of oxygen to the storage atmosphere, and delayed by the addition of carbon dioxide or removal of oxygen. Ethylene had no apparent effect on ripening. Fruits maintained under low relative humidities ripened faster than those stored under high-humidity conditions. Dipping the fruits in a solution of indole acetic acid at concentrations between 10 −4 and 10 −2 M accelerated ripening. Levels of both ascorbic acid and glucose increased to a maximum at the climacteric, but decreased as the fruits became over ripe. The stage of “eating” ripeness occurred at the climacteric. Recommended conditions for storing custard apple are: temperatures between 15 and 20° C, low oxygen and ethylene tensions coupled with 10% carbon dioxide and a relative humidity of 85%–90% in the storage atmosphere.

COLOR DEVELOPMENT AND CAROTENOID LEVELS IN RIN AND NOR TOMATOES AS INFLUENCED BY ETHEPHON, LIGHT AND OXYGEN

ABSTRACTFruits of rin and nor tomato (Lycopersicon esculentum) mutants do not develop normal pigmentation and undergo normal ripening. The effects of ethephon, light and O2 on color development and carotenoid levels in harvested fruits were determined. Increasing concentration of ethephon increased red surface color (color difference meter a values). The addition of light greatly enhanced red color development. Fruits of rin were more responsive to light and ethephon than were fruits of nor. Oxygen (100%) enhanced color development in nor fruits held in dark conditions, but it was detrimental to ethephon induced color development in both rin and nor fruits exposed to light. Ethephon and light each substantially enhanced beta‐carotene and lycopene levels. Fruits exposed to both ethephon and light had further increases in beta‐carotene and lycopene levels. In rin and nor fruits, it appears that light and ethylene are important in stimulating carotenoid synthesis and regulating levels of particular carotenoids.

Carbon Dioxide, Ethylene, and Color Development in Ripening Mature Green Bell Peppers1

Abstract Mature green bell pepper fruit (Capsicum annuum L. cv. Yolo Wonder) exhibited a non-climacteric pattern of ethylene and carbon dioxide production during normal ripening and red color development at 24°C. Exposing detached mature green fruit to 500 ppm propylene in air for 48 hours, did not induce an increase in ethylene or carbon dioxide production. Wounding excised plugs of ovary wall tissue caused an increase in carbon dioxide production within one day, and an increase in ethylene production by the second day.

Changes in fruit growth and pectic content in Coffea canephora (robusta) in relation to the exogenous application of ethylene

Fruit ripening in robusta coffee induced chemically by ethylene (CEPA) is clearly manifested in enhanced growths of whole fruits and mesocarp and decreased pectic substances. Pectic changes in coffee appear to be directed by endogenous auxins. Foliar application of NPK prevented these changes at lower concentrations of ethylene (150 and 360 ppm) but the blockage was removed at higher doses (720 ppm). NPK treatment necessitates higher dosage of ethylene to obtain normal ripening, as these minerals increased the thresholds of ethylene in coffee fruits by some unknown mechanism.

Changes in Ultrastructure and Pigment Content During Development and Senescence of Fruits of Normal and rin and nor Mutant Tomatoes

Fruits of the normal Rutgers tomato cultivar and of the rin and nor mutants were examined at the following times: Rutgers at 17, 21, 32, 45, 47, 50 and 55 days after anthesis; rin and nor at 17, 21, 32, 50, 65, 78 and 95 days after anthesis. Ripening in Rutgers fruits began at about 47 days, and fruits were fully ripe by 55 days after anthesis. Full size was reached in both Rutgers and in the mutant fruits about 50 days after anthesis. Rin fruits subsequently turned yellow, and nor fruits developed some pink colour, but the fruits of both mutants remained sound and comparatively firm for up to 95 days after anthesis. No unique differences in ultrastructure were noted between Rutgers and mutant fruits except that myelin figures were observed in 21- and 32-day nor fruits and spiral membrane tubules were found in the epidermis of 95-day rin fruits. In Rutgers fruits, the major change was the transformation of chloroplasts to chromoplasts during ripening; this transformation was completed within 5 days. A similar, but much slower and less complete, transformation was noted in the mutants. Some grana and chlorophyll were present even in 95-day fruits, although rin and nor fruits began to lose chlorophyll and to accumulate coloured carotenoids from the time the fruits reached full size. The slow changes in ultrastructural transformation of plastids, paralleled by the changes in colour, suggest either suppression of nuclear action or lack of capacity to produce cellular components essential for normal ripening. The latter suggestion was favoured by current information on the physiology of the mutants.

CHILLING INJURY IN GREEN BANANA FRUIT: CHANGES IN PEROXIDASE ISOZYMES IN SOLUBLE AND PARTICULATE POOLS

Green banana fruit manifested severe chilling injury after 5–7 days storage at 5°C and 80% relative humidity. (Severe chilling injury is described here as a failure of the fruit to ripen on removal to conditions conducive to normal ripening.) The recoverable “wall bound” peroxidase fraction exhibited a sharp decline during this initial period of stress. Subsequent storage of severely chilled fruit at. 5°C resulted in a gradual increase in the “soluble” peroxidase pool and a rise in “wall bound” peroxidase to levels comparable to normal green fruit. After 30 days storage of fruit at 5°C the “soluble” and “wall bound” fractions of peroxidase peaked and declined rapidly in the latter pool. The increase in peroxidase of cold stressed fruit involved qualitative changes in isozyme species that differed from those isozymes which emerge during normal fruit ripening. It is suggested that the initial decrease in “wall bound” peroxidase results in a loss in capability of the tissue to adapt to low temperature stress. The belated increase in peroxidase activity may be associated with a typical “cold hardening” response which develops only after an irreversible or “plastic strain” damage has occurred

Ethylene-stimulated Synthesis of Ribosomes, Ribonucleic Acid, and Protein in Developing Fig Fruits

Ethylene profoundly stimulates the growth and ripening of fig fruits if applied during the second half of growth period II, the slow growth phase of the characteristic double sigmoid growth curve (7, 9). Although ethylene-treated fruits ripened 2 to 3 weeks early, within 6 days from inception of treatment, they were indistinguishable from ripe, untreated fruits (7). Moreover, ethylene induced a typical respiratory climacteric rise identical to that associated with normal ripening and the initiation of growth period III (7). Recently, Hulme et al. (4) have demonstrated an ethylenestimulated synthesis of unspecified types of RNA in apple tissue slices in concert with climacteric phenomena. Our intent in this study was to use the dramatic response of fig fruits to ethylene along with available analytical techniques to discern the temporal aspects of stimulated RNA synthesis and the forms of RNA being synthesized.

Pectic changes occurring in elberta peaches suffering from woolly breakdown

The processes which take place in peaches stored under conditions that favour development of woolly breakdown, were found to be connected with the metabolism of the pectic substances. In fruit held under conditions that ensure its normal ripening (above 8°), a gradual degradation of protopectin to soluble pectin occurs and the amount of pectates remains constant. However, in fruit that is held under conditions which favor woolly breakdown (below 8°), the insoluble pectic fractions begin to increase after approximately 2 weeks' storage. As a result, the total amount of pectic substances appears to increase. This change evidently occurs partially due to the action of pectin-methyl-esterase. During normal ripening the activity of this enzyme increases until the fruit attains full ripeness and then begins to decrease. In fruit with incipient woolliness, enzyme activity is initially low, and only begins to rise during the second stage of storage. Thus, an insoluble low-methoxyl pectin of high molecular weight is formed in the cell walls, which is capable of 'holding' water in a gel-like structure. It is suggested that this could be the reason for loss of juiciness in woolly peaches.

Storage of Bananas in Polyethylene Bags with an Ethylene Absorbent1

Abstract Storage of preclimacteric bananas in sealed polyethylene showed promise. After a reasonable period of storage the bags must be opened to allow normal ripening. Endogenous ethylene was a source of potential ripening in these sealed poly bags. Hence, an ethylene absorbent was usually essential. A commercial product, ‘Purafil’ was capable of absorbing this ethylene and extending the storage life of preclimacteric fruits.

Storage of Bananas in Polyethylene Bags with an Ethylene Absorbent1

Abstract Storage of preclimacteric bananas in sealed polyethylene showed promise. After a reasonable period of storage the bags must be opened to allow normal ripening. Endogenous ethylene was a source of potential ripening in these sealed poly bags. Hence, an ethylene absorbent was usually essential. A commercial product, ‘Purafil’ was capable of absorbing this ethylene and extending the storage life of preclimacteric fruits.

Protein synthesis in relation to fruit ripening

The relationship of protein synthesis to ripening of Bartlett pears was determined by investigating several parameters of ripening under conditions of ‘steady-state’ or ‘new’ protein synthesis. The investigations were directed at the question of dependency of ripening on the activity of newly synthesized or pre-existing proteins. It was found that protein synthesis is required for normal fruit ripening and the proteins synthesized early in the ripening process include enzymes required for ripening.14C-Phenylalanine was incorporated into fruit proteins, which were subsequently separated by acrylamide gel electrophoresis, of fruits at various stages of ripening. Fruit ripening and ethylene synthesis are inhibited when protein synthesis is blocked by treatment with cycloheximide at the early-climacteric stage. However, once ripening progresses beyond a certain stage ripening, but not protein synthesis, proceeds equally well in the presence or absence of cycloheximide indicating that the enzymes involved in ripening are synthesized soon after ripening has been initiated. Ethylene does not overcome cycloheximide inhibition of ripening or protein synthesis. It is concluded that normal ripening of pear fruits requires the coordinated synthesis of enzymes whose concentrations are limiting the rate of the various ripening reactions. The synthesis of these enzymes takes place for the most part during the early stage of ripening before marked physical changes become apparent in the tissue. Ethylene is required in physiologically active concentrations in order to initiate this ripening syndrome and can act only if protein synthesis is allowed to proceed. Without ethylene, fruits which otherwise are ready to ripen continue to synthesize those proteins for which capacity already exists.

Protein Synthesis in Relation to Ripening of Pome Fruits

Protein synthesis by intact Bartlett pear fruits was studied with ripening as measured by flesh softening, chlorophyll degradation, respiration, ethylene synthesis, and malic enzyme activity. Protein synthesis is required for normal ripening, and the proteins synthesized early in the ripening process are, in fact, enzymes required for ripening. (14)C-Phenylalanine is differentially incorporated into fruit proteins separated by acrylamide gel electrophoresis of pome fruits taken at successive ripening stages. Capacity for malic enzyme synthesis increases during the early stage of ripening. Fruit ripening and ethylene synthesis are inhibited when protein synthesis is blocked by treatment with cycloheximide at the early-climacteric stage. Cycloheximide became less effective as the climacteric developed. Ethylene did not overcome inhibition of ripening by cycloheximide. The respiratory climacteric is not inhibited by cycloheximide. It is concluded that normal ripening of pome fruits is a highly coordinated process of biochemical differentiation involving directed protein synthesis.

Phenolase activity in tomato fruit in relation to growth and to various ripening disorders.

AbstractAn efficient method for the extraction of phenolase from tomato fruit is described. It has indicated that phenolase activity increases towards maturity and then decreases somewhat during normal ripening. The red area of fruit which showed a physiological ripening disorder known as ‘blotch’ contained an abnormally high activity while the green areas contained an even higher activity. Tomatoes exhibiting ‘blossom‐end’ rot also contained enhanced activity, especially in the affected region. Levels of phenolase in tomato species other than Lycopersicon esculentum have also been examined. The browning symptoms associated with specific physiological ripening disorders are discussed in relation to phenolase activity and the availability of phenolic substrates.

Studies on Sterility in Lower Spikelets of Barley : Part V On the change in Physiological Function of Barley by means of top-dressing of nitrogen fertilizer on the stage of flag-leaf emergence.

The present paper reports the results obtained from our observation of growing process of lower spikelets of var. Yukiwarimugi cultivated at upland field, both when nitrogen fertilizer is and is not top-dressed and from our examination of the change in physiological functions in case of top-dressing of the fertilizer. 1) In a group of dressing plots, flag-leaf at the heading time shows remarkable increase both in their fresh weight and dry weight; the chlorophyll contents also increase. And in that case osmotic pressure of flag-leaf sheath is comparatively high, and amount of bleeding sap examined at pedunde indreass. 2) So far as non-top-dressing plots are concerned, Qo2 value of spikelets at the lower part of the ear is lower than that of spikelets at the middle part of the ear; whereas in top-dressing plots Qo2 value is higher with the lower spikelets. The similar tendency is seen in flag-leaves. 3) The activity of dehydrogenase, in non-top-dressing plots, is degenerate in lower spikelets than in spikelets in the middle part of the ear, whereas in top-dressing plots, their activity in the former is promotive. The results of T. T. C. reaction indicates the similar tendency. 4) The activity of ascorbic-acid-oxidase is lower with the lower spikelets than with spikelets at the middle part of the ear. 5) After the flag-leaf has been fully opened, nitrogen and carbohydrate content in the flag-leaf, in spikelets at the middle and the lower parts of the ear, the top-internode and in the flag-leaf node, are higher with the top-dressing plots than the non-top-dressing plots. 6) The ratio of sugar content in those parts of the ear and the top-internode mentioned in 5) to sugar content in a flag-leaf, is smaller in the top-dressing plots than the other, especially in the group of spikelets in the lower part of the ear. In other words, in the top-dressing plots, the sugar concentration gradient between the lower part of an ear and the flag-leaf increases. 7) The C/N ratio of the spikelets, in the top-dressing plots, is seen to be lower than in the non-top-dressing plots. This is presumably because the enzyme activity and respiration being promoted by top-dressing, and thus the carbohydrates being actively utilized. This seems to make the gradient in sugar concentration larger, and probably promote the translocation of carbohydrate from flag-leaf to ear. Judging from the above results, physiological activity in the lower spikelets is promoted by the top-dressing and thus accelerates the growing of the spikelets that is apt to degenerate. It is consequently presumed that this fact enables the normal ripening of spikelets, in other words ensure the efficienty translocation from the flag-leaf to the lower parts of the ear.

The Effect of Copper upon the Activity of Bacteria Associated with Swiss Cheese Manufacture

Summary Data have been presented which demonstrate that bacteria associated with Swiss cheese manufacture vary considerably in their behavior toward copper. Copper had no pronounced effect upon the growth and acid production by S. thermophilus and three species of homofermentative lactobacilli. Conversely, copper increased the lag phase and decreased the growth rate of the three P. shermanii cultures. A similar lag in volatile acid and CO2 production was observed. These effects were roughly proportional to the copper concentration in the growth medium. Although copper depressed the rate of growth, volatile acid and C02 production after 13 days were approximately equal for all levels of copper studied. Copper did not alter the ratio of acetic to propionic in the volatile acid fraction. Preliminary evidence indicated that high levels of copper (18.0ppm.) in Swiss-type cheese exerted an unfavorable influence on the course of ripening, whereas a normal and satisfactory ripening occurred in cheeses containing 0 to 0.5 and 7.5 to 8.0ppm. copper.

STUDIES OF THE TOMATO IN RELATION TO ITS STORAGE: II. THE EFFECTS OF ALTERED INTERNAL ATMOSPHERE UPON THE RESPIRATORY AND RIPENING BEHAVIOUR OF TOMATO FRUITS STORED AT 12.5 °C.

When a mature green tomato fruit is stored at 12.5 °C. either with or without its stem, the expected respiratory climacteric accompanies the colour change associated with ripening. When the stem is removed and the stem scar area is covered carefully with hot paraffin wax, the fruit thereafter ripens slowly with a low, relatively constant rate of carbon dioxide output. These characteristics are ascribed to "auto-gas" storage resulting from restricted diffusion at the stem scar. The effect of waxing is reversible within limits since removal of the artificial seal after one month has resulted in a return to normal ripening and respiratory behaviour.When yellowing, yellow orange, and full red fruits are stored either with or without their stems, they complete in storage those phases of the respiratory climacteric that had not been completed before detachment from the plant. The careful waxing of fruits picked at these stages of maturity inhibits further coloration and reduces the rate of carbon dioxide output to the same extent as in fruits waxed at the mature green stage. The respiratory drift of fruits picked and stored unwaxed at the early "growing green" stage is characterized by two distinct peaks. Such fruits eventually ripen and the second peak is associated with the colour change that accompanies ripening. Similar fruits stored with stem scars waxed fail to ripen before their pathological "death" and their respiration rate is reduced by the waxing treatment.When yellowing and yellow-orange fruits are waxed, they become soft and highly susceptible to fungal attack before their ripening coloration has been completed. To inhibit the softening process in stored tomatoes, it thus appears to be necessary to apply wax before ripening has commenced. Unwaxed fruits become highly susceptible to fungal wastage only after attaining full ripeness. Waxed fruits on the other hand are subject to fungal wastage when green or partially coloured as well as when fully ripened. This is attributed to the progress of softening in the absence of the usual colour change associated with ripening. Waxing of the stem scars does not act as a deterrent to storage moulds at the waxed area. The waxed tomato has been found to be subject to several physiological disorders the symptoms of which are described.