María Teresa Pretel

Physico-Chemical and Physiological Changes during Fruit Development and Ripening of Five Loquat (Eriobotrya Japonica Lindl.) Cultivars:

Physico-chemical and physiological changes during development and ripening of five loquat cultivars (Eriobotrya japonica Lindl., cv. Algerie, Cardona, Golden, Magdall and Peluche) were determined. Fruit growth showed a sigmoid curve in all loquat cultivars. A good relationship between duration of fast growth phase and fruit size was found. In addition, a positive correlation was also established between seed number and fruit size, and between seed weight and both fruit and flesh weight. Colour changes, sugar content increase and the decrease in fruit firmness and organic acids started simultaneously when loquat fruits were in the phase of fast growth, and at about 70-80% of their final weight. These physico-chemical changes related to fruit ripening coincided with an increase in both ethylene production rate and free and total 1-aminocyclopropane-1 -carboxylic acid (ACC) content in the flesh. In addition, a small respiration peak associated with ripening was also detected. These results indicated that loquat fruits of all five studied cultivars showed a pattern of ripening in the tree that could be classified as climacteric, with relatively low ethylene production evolving at an early phase of fruit development.

Antioxidant and Nutritional Properties of Date Fruit from Elche Grove as Affected by Maturation and Phenotypic Variability of Date Palm

Some parameters related to nutritive and functional properties were evaluated in date fruit from seven date palms from the Elche grove along the maturation process, in order to obtain information about differences due to phenotypic variability. Results showed that sugar and organic acid concentration were different depending on date palm, the highest levels being reached at 100% Rutab stage, with glucose and fructose as the predominant sugars and malic acid as the major organic acid. Hydrophilic total antioxidant activity (HTAA) was high and correlated to phenolic content, with maxima levels being found at early, medium or late Khalal stages, depending on date palm. In addition, significant differences were found in both, phenolic concentration and HTAA among date palm and maturation stages, while lipophilic total antioxidant activity (LTAA) was very low, without changes along maturation and not correlated to HTAA. Then, date fruit from Elche grove could serve as a good source of natural antioxidant and it would be advisable to consume them at medium or late Khalal stages, in order to achieve the maxima nutritional (high concentration of sugars and organic acids), organoleptic (appropriated firmness levels, yellow or red color and low astringency) and functional properties with benefits to human health.

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.

Changes in free polyamine concentration induced by salt stress in seedlings of different species

Growth rate, mineral composition and changes in polyamine concentration induced in response to salinity were studied in six crop species: spinach, lettuce, bean, pepper, beetroot and tomato. Salinity decreased growth rate, but sensitivity differed amongst the species: pepper being the most sensitive, followed by bean, tomato, lettuce and spinach, with beetroot being the most tolerant. The increase of Na+ and total cation with salinity in shoots was the highest in spinach and beetroot, the most tolerant species, while in pepper it was the lowest. Changes in putrescine (Put) concentration in shoots were related to salinity tolerance (increased in the most sensitive), while changes in spermidine (Spd; decreases) and spermine (Spm; increases) were similar with most species, except for pepper in which salinity strongly increased Put, Spd and Spm. Therefore, total polyamine concentration increased in pepper shoot, while it decreased in the other species. Thus, results show that Put accumulation was a consequence of salt stress in the most sensitive species, while salt tolerant species (beetroot) showed little change in polyamine concentration, and higher concentration in both Na+ and total cations. The role of polyamines or cation increased concentration after saline treatment in species with different salt tolerance is discussed.

Physicochemical changes during date ripening related to ethylene production

Some physicochemical parameters related to ripening and their relationship with ethylene were studied in date fruits (Phoenix dactyliferaL. type Negros). Dates were harvested and classified into sixteen ripening stages according to their color, ranging from yellow-greenish to dark brown. Fruit firmness decreased through the different ripening stages, while the ripening index, expressed as the relation between soluble solids and acidity, increased. The greatest loss of fruit firmness correlated with the greatest increases in both polygalacturonase and •-galactosidase activities. In early ripening stages, a small peak in ethylene production was detected, followed by a peak in respiration rate, suggesting that a date could be considered as a climacteric fruit, with the plant hormone ethylene being responsible for changes in color, fruit firmness, soluble solids content and acidity.

PRESERVATIVE SOLUTIONS CONTAINING BORIC ACID DELAY SENESCENCE OF CARNATION FLOWERS

We investigated the effect of a preservative solution containing boric acid on the senescence of cut carnation flowers (Dianthus caryophyllus L. cv. Master). A 24-h pulse treatment with the preservative solution containing 50, 75 or 100 mM boric acid or continuous treatment with 1 mM boric acid resulted in strong inhibition of the climacteric ethylene production. Both the pulse and continuous treatments significantly increased flower longevity. Free and conjugated 1-aminocyclopropane-1-carboxylic acid (ACC) and ACC oxidase activity increased in carnation petals during senescence, although significantly less in boric acid-treated carnations than in control flowers. The levels of putrescine increased as senescence progressed in both control and boric acid-treated carnations and an increase in spermidine levels was higher in treated carnations. Abscisic acid levels in petals also increased during senescence, but much less in boric acid-treated carnations. It is concluded that boric acid prevents the early rise in ethylene production and considerably improves carnation vase life.

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.

Note. The ripening of Prunus persica fruits with a dominant flat allele Nota. Maduración de frutos de Prunus persica con un alelo dominante de la forma achatada

The changes of peaches (Prunus persica, L.) with a predominant flat allele were studied during their ripening on the tree. Physicochemical and physiological parameters were analyzed between days 101 and 121 after fruit set. During this period, the weight ranged from 65 g (corresponding to fruit growth stage III) up to a stabilized weight of 90 g when the fruit was ripe. The color changes that characterized fruit ripening began to appear on day 112 after fruit set, with a decrease in the hue angle value both in the skin and pulp. Firmness diminished along the experience from 6.75 to 3.03 Monet units in ripe state. Ripened fruit was also characterized by a soluble solid content of 13.43 °Brix and 0.178% malic acid as titratable acidity. The ripeness index increased throughout maturation from 25.41 at the outset to 44.42 on day 112 after fruit set, and 75.45 at the end of the experiment. The fruit showed a clear climacteric behavior with increased ethylene production and respiration rate. The onset in both processes started on day 112 after fruit set, reached a maximum on day 116, and decreased thereafter. Changes in the content of free and conjugated 1-aminocyclopropane-1-carboxy lic acid (ACC) were coincident with those of ethylene evolution throughout ripening. In regard to polyamine levels, putrescine showed a peak slightly later than that of ethylene and ACC.

Roasting and packaging in nitrogen atmosphere protect almond var. Guara against lipid oxidation.

The effect of packaging in nitrogen (N2) atmosphere or in air on the quality of peeled and roasted almond var. Guara during storage for 20 weeks at 20 °C ± 1 °C and 65–70% relative humidity (RH) was studied. No changes in the sugar, fat, protein or fiber contents were observed during the storage period nor in color. Only the lipid fraction showed significant changes with the kind of packaging atmosphere. The composition of fatty acids remained unchanged during the 5 month storage in all the samples. Packaging in N2 atmosphere was seen to have a protective effect against the accumulation of conjugated dienes (CD) in peeled almonds, while in roasted almonds, the protective effect was lower and even nil by the end of storage. The contrary effect was observed for the ultraviolet (UV; K270) index which increased more slowly in the roasted samples packaged in N2, while in peeled samples it reached the same levels at the end of storage regardless of the packaging atmosphere. No effect of the packaging atmosphere was observed on the evolution of the peroxide value in the tested samples (peeled or roasted almonds). None of these changes in the lipid fraction was reflected in the final sensory quality of the samples and the taster panel found no changes in the sensory quality in any case.

Obtaining and storage of ready-to-use segments from traditional orange obtained by enzymatic peeling

The aim of this study was to optimize all parameters implied in the process of obtaining orange segments as minimally processed product by enzymatic peeling, from the method of segment obtaining to the storage conditions, and also to evaluate two films with different permeability. Enzymatic peeling was carried out by fruit infusion under vacuum conditions in a commercial preparation of pectinases and cellulases (Peelzym II). The best condition to obtain Cadenera segments by enzymatic peeling was 1 mL/L of Peelzym II applied at 53 kPa with three vacuum pulses of 2 min and a subsequent period of 30 min in the enzymatic solution at atmospheric pressure. The segments were packaged in two films with different permeability and they were stored for 10 days at 4 °C. Samplings were carried out after 4, 7 and 10 days of storage. The results showed that the concentration of CO2 in the less permeable film (PA 120) ranged between 0.7 and 1.2 mL/100 mL, while in the most permeable one (PA 240) was around 0.2 mL/100 mL. Under these conditions, the weight loss was kept at low levels until day 7 of storage, showing a significant increase after 10 days. Colour (a/b) increased with the peeling process and it remained without significant changes during the whole storage period for both films. The antioxidant capacity slightly decreased after 10 days of storage. The microbial flora was reduced after the enzymatic peeling. Both the sensory and the microbiological quality were kept in adequate levels for consumption during 7 days. From this moment, they lost sweetness and aroma and the microbial development increased. Thus, the use of the most permeable film and a maximum storage time of 7 days are recommended to maintain the most quality of the segments.