Postharvest Biology and Technology of Loquat (Eriobotrya japonica Lindl.)

Loquat (Eriobotrya japonica Lindl.) fruit is a rich source of carotenoids, flavonoids, phenolics, sugars, and organic acids. Although it is classified as a non-climacteric fruit, susceptibility to mechanical and physical bruising causes its rapid deterioration by moisture loss and postharvest decay caused by pathogens. Anthracnose, canker, and purple spot are the most prevalent postharvest diseases of loquat fruit. Cold storage has been used for quality management of loquat fruit, but the susceptibility of some cultivars to chilling injury (CI) consequently leads to browning and other disorders. Various techniques, including cold storage, controlled atmosphere storage, hypobaric storage, modified atmosphere packaging, low-temperature conditioning, heat treatment, edible coatings, and postharvest chemical application, have been tested to extend shelf life, mitigate chilling injury, and quality preservation. This review comprehensively focuses on the recent advances in the postharvest physiology and technology of loquat fruit, such as harvest maturity, fruit ripening physiology, postharvest storage techniques, and physiological disorders and diseases.

Determination of the relationship between respiration rate and ethylene production by fruit sizes of different tomato types

BACKGROUND

Tomatoes of different types and cultivars are grown in different parts of the world. Accordingly, the phenological, pomological and biochemical characteristics of these types and cultivars may differ from each other, and therefore their ripening behaviours may also differ. The present study aimed to determine the respiration rate and ethylene production of twelve commonly grown cultivars in Turkey at harvest and during the ripening stage. The fruits were harvested at the mature green stage and categorized according to their size as small, medium and large-fruited cultivars.

RESULTS

At harvest time, the highest respiration rate was determined from 'Moda' (small-fruited) cultivar and the lowest was from 'Elips' (medium-fruited). The highest ethylene production was determined from 'Sarikiz' (small-fruited) and the lowest was from 'Alberty' (large-fruited). All tomato cultivars examined in the study showed climacteric respiration behavior during the ripening, and it was determined that small-fruited types had a higher respiration rate and ethylene production compared to medium and large-fruited ones. 'Sarikiz' (small-fruited) had the highest climacteric peak and 'Gulpembe' (large-fruited) had the lowest. Moreover, it was determined that the respiration rate of small-fruited cultivars were 5.01-fold higher compared to other cultivars and this type of cultivars produced 4.19-fold higher ethylene compared to big-fruited cultivars at harvest. Medium-fruited tomatoes had 1.90-fold higher respiration rate and 1.64-fold ethylene production compared to big-fruited tomatoes.

CONCLUSION

It was determined that fruit size and respiration rate were related independently of the cultivars, although there was no relationship between fruit size and ethylene production. © 2022 Society of Chemical Industry.

Carotenoid Accumulation and the Expression of Carotenoid Metabolic Genes in Mango during Fruit Development and Ripening

Carotenoids are considered to be important components in mango fruits. However, there is a lack of understanding about the regulation of carotenoids in mango. To gain an insight into the carotenoid metabolism pathway, carotenoid content and the expression of carotenoid metabolic genes were investigated in the peel and pulp of mango during fruit development and ripening in three cultivars, ‘Kaituk’, ‘Nam Dok Mai No.4′, and ‘Nam Dok Mai Sithong’, which are different in color. The highest carotenoid content was observed in ‘Kaituk’, followed by ‘Nam Dok Mai No.4′ and ‘Nam Dok Mai Sithong’, with the major carotenoid being β-carotene. The gene expression analysis found that carotenoid metabolism in mango fruit was primarily regulated at the transcriptional level. The changing patterns of carotenoid biosynthetic gene expression (MiPSY, MiPDS, MiZDS, MiCRTISO, MiLCYb, MiLCYe, MiHYb, and MiZEP) were similar to carotenoid accumulation, and ‘Kaituk’ exhibited a higher expression level than the other two cultivars. In addition, the differential regulation of carotenoid catabolic genes was found to be a mechanism responsible for variability in carotenoid content among the three mango cultivars. The expression of carotenoid catabolic genes (MiCCD1, MiNCED2, and MiNCED3) more rapidly decreased in ‘Kaituk’, resulting in a larger amount of carotenoids in ‘Kaituk’ than the other two cultivars.

Beyond the limits of photoperception: constitutively active PHYTOCHROME B2 overexpression as a means of improving fruit nutritional quality in tomato

Photoreceptor engineering has recently emerged as a means for improving agronomically beneficial traits in crop species. Despite the central role played by the red/far-red photoreceptor phytochromes (PHYs) in controlling fruit physiology, the applicability of PHY engineering for increasing fleshy fruit nutritional content remains poorly exploited. In this study, we demonstrated that the fruit-specific overexpression of a constitutively active GAF domain Tyr252 -to-His PHYB2 mutant version (PHYB2Y252H ) significantly enhances the accumulation of multiple health-promoting antioxidants in tomato fruits, without negative collateral consequences on vegetative development. Compared with the native PHYB2 overexpression, PHYB2Y252H -overexpressing lines exhibited more extensive increments in transcript abundance of genes associated with fruit plastid development, chlorophyll biosynthesis and metabolic pathways responsible for the accumulation of antioxidant compounds. Accordingly, PHYB2Y252H -overexpressing fruits developed more chloroplasts containing voluminous grana at the green stage and overaccumulated carotenoids, tocopherols, flavonoids and ascorbate in ripe fruits compared with both wild-type and PHYB2-overexpressing lines. The impacts of PHYB2 or PHYB2Y252H overexpression on fruit primary metabolism were limited to a slight promotion in lipid biosynthesis and reduction in sugar accumulation. Altogether, these findings indicate that mutation-based adjustments in PHY properties represent a valuable photobiotechnological tool for tomato biofortification, highlighting the potential of photoreceptor engineering for improving quality traits in fleshy fruits.

Interplay between hormones and assimilates during pear development and ripening and its relationship with the fruit postharvest behaviour

The ability of European pears (Pyrus communis L.) to ripen immediately after harvest is cultivar-dependent and relies on a range of physiological and biochemical events occurring during fruit growth and development that remain largely unknown. To gain further knowledge on these events, changes in the content of sugars, acids, major hormones and ethylene precursors or related enzymes were studied in two pear varieties ('Blanquilla' and 'Conference') with known differences in their postharvest ripening behaviour. In both cultivars, low contents of abscisic acid (ABA) seemed to be a prerequisite to initiate on-tree fruit ripening including sugar accumulation and softening. In 'Blanquilla' pears, the enhanced potential to produce ethylene and thereby to ripen upon harvest was associated to a late increase in ABA content paralleled by an accumulation of indole 3-acetic acid (IAA). In turn, the inability of 'Conference' fruit to produce ethylene upon harvest appeared to be related to a coordinated action of gibberellins (more specifically GA₁), salicylic acid (SA) and jasmonic acid (JA), which remained at high concentrations during the latest phases of fruit growth. Collectively, our results highlight that a complex hormonal cross-talk during the development and on-tree ripening of pear fruit may finally determine the ability of the fruit to ripen upon harvest.

What does the RuBisCO activity tell us about a C3-CAM plant?

Plants that perform the Crassulacean acid metabolism (CAM), which obtain CO₂ overnight and convert it mainly in malic acid, successfully grow in environments with water and nutrient shortages, that is partly associated with their higher water- and nitrogen-use efficiencies. Water and nutrient limitations can impair photosynthesis through the reduction of RuBisCO and increment of photorespiration, disturbing the plant carbon balance. In this context, we conducted a controlled experiment with the epiphytic C₃-CAM bromeliad Guzmania monostachia to investigate how the combined water and nutritional deficits affect the activity of RuBisCO and its activation state (RAS), and to evaluate the efficiency of photosynthesis during the transition from C₃ to CAM. Apart from an increase in CAM activity, bromeliads submitted to both water and nutritional deficits showed higher RAS values and unaltered RuBisCO activity compared to C₃ bromeliads and, surprisingly, the maximum quantum efficiency of photosynthesis increased. Glucose, fructose and starch levels were maintained, while sucrose concentrations increased over time. These results, combined with the high RAS values, suggest an increased efficiency of RuBisCO functioning. Our results reinforce the ability of epiphytic bromeliads to deal with stressful habitats by a higher efficiency of RuBisCO during the transition to CAM, another feature that may allow their evolution in the epiphytic environment.

A comprehensive study on the main physiological and biochemical changes occurring during growth and on-tree ripening of two apple varieties with different postharvest behaviour

Apple quality and the storage potential likely depend on a range of physiological and biochemical events occurring throughout fruit development and ripening. In this study, we investigated the major physiological (ethylene production and respiration) and biochemical changes (related to sugar and malic acid content as well as antioxidant metabolism) occurring during growth and on-tree ripening of two apple varieties ('Granny Smith' (GS) and 'Early Red One' (ERO)) with known differences in their postharvest behaviour, mainly firmness loss and susceptibility to superficial scald. Our results demonstrate that the higher storability and the limited loss of firmness of 'GS' fruit was associated to a higher acid content, mainly malic acid, that seemed to be regulated already at fruit set (20 DAFB). The reduced loss of firmness during storage in 'GS' was also associated to the fruit inability to produce ethylene upon harvest resulting from very low 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) activity. Sugar accumulation, on the other hand, was similar among both varieties as was also observed for the rate of fruit growth or the fruit respiration pattern. In addition, the higher susceptibility of 'GS' if compared to 'ERO' to superficial scald was not associated to peroxidative damage (malondialdehyde accumulation) nor to higher levels of the sesquiterpene α-farnesene but rather mediated by a fruit antioxidant imbalance resulting from higher H₂O₂ levels and lower antioxidant (peroxidase) enzymatic capacity. The interplay between ethylene, respiration and antioxidants or sugars and organic acids during apple growth and development is further discussed.

Proton and anion transport across the tonoplast vesicles in bromeliad species

Crassulacean acid metabolism (CAM) is one of the key innovations in the Neotropical family Bromeliaceae that has enabled many of its species to occupy seasonally water-limited terrestrial environments or microclimatically arid epiphytic niches. However, the relationship between CAM activity and the transport processes responsible for vacuolar organic-acid accumulation at night has not been systematically explored in this family. In the present investigation, ATP- and PPi-dependent proton transport rates were studied in tonoplast membrane vesicles isolated from leaves of six CAM and one C3 species of bromeliads. A consistent feature of these species was the high activity of the tonoplast ATP-driven H+ pump, which, when averaged across the seven species tested, showed a higher specific activity than the tonoplast PPi-driven H+ pump. For all CAM species, the rate of ATP-dependent proton transport into the tonoplast vesicles was strongly influenced by the nature of the balancing organic-acid anion, which displayed the following order of effectiveness: fumarate>malate>citrate. Measurements of leaf organic-acid content in six CAM bromeliads at dusk and dawn showed that nocturnal accumulation of malate exceeded citrate by a factor of ~2.4-20.0-fold in five of six bromeliad species used in this study, demonstrating a close correlation between the CAM rhythm and the intrinsic properties of the vacuolar membrane across which these organic acids are transported.

Ethylene biosynthesis and perception during ripening of loquat fruit (Eriobotrya japonica Lindl.)

In order to gain insights into the controversial ripening behavior of loquat fruits, in the present study we have analyzed the expression of three genes related to ethylene biosynthesis (ACS1, ACO1 and ACO2), two ethylene receptors (ERS1a and ERS1b), one signal transduction component (CTR1) and one transcription factor (EIL1) in peel and pulp of loquat fruit during natural ripening and also in fruits treated with ethylene (10μLL^-1) and 1-MCP (10μLL^-1), an ethylene action inhibitor. In fruits attached to or detached from the tree, a slight increase in ethylene production was detected at the yellow stage, but the respiration rate declined progressively during ripening. Accumulation of transcripts of ethylene biosynthetic genes did not correlate with changes in ethylene production, since the maximum accumulation of ACS1 and ACO1 mRNA was detected in fully coloured fruits. Expression of ethylene receptor and signaling genes followed a different pattern in peel and pulp tissues. After fruit detachment and incubation at 20°C for up to 6days, ACS1 mRNA slightly increased, ACO1 experienced a substantial increment and ACO2 declined. In the peel, these changes were advanced by exogenous ethylene and partially inhibited by 1-MCP. In the pulp, 1-MCP repressed most of the changes in the expression of biosynthetic genes, while ethylene had almost no effects. Expression of ethylene perception and signaling genes was barely affected by ethylene or 1-MCP. Collectively, a differential transcriptional regulation of ethylene biosynthetic genes operates in peel and pulp, and support the notion of non-climacteric ripening in loquat fruits. Ethylene action, however, appears to be required to sustain or maintain the expression of specific genes.

Comparative Transcriptional Analysis of Loquat Fruit Identifies Major Signal Networks Involved in Fruit Development and Ripening Process

Loquat (Eriobotrya japonica Lindl.) is an important non-climacteric fruit and rich in essential nutrients such as minerals and carotenoids. During fruit development and ripening, thousands of the differentially expressed genes (DEGs) from various metabolic pathways cause a series of physiological and biochemical changes. To better understand the underlying mechanism of fruit development, the Solexa/Illumina RNA-seq high-throughput sequencing was used to evaluate the global changes of gene transcription levels. More than 51,610,234 high quality reads from ten runs of fruit development were sequenced and assembled into 48,838 unigenes. Among 3256 DEGs, 2304 unigenes could be annotated to the Gene Ontology database. These DEGs were distributed into 119 pathways described in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. A large number of DEGs were involved in carbohydrate metabolism, hormone signaling, and cell-wall degradation. The real-time reverse transcription (qRT)-PCR analyses revealed that several genes related to cell expansion, auxin signaling and ethylene response were differentially expressed during fruit development. Other members of transcription factor families were also identified. There were 952 DEGs considered as novel genes with no annotation in any databases. These unigenes will serve as an invaluable genetic resource for loquat molecular breeding and postharvest storage.

Implications of leaf ontogeny on drought-induced gradients of CAM expression and ABA levels in rosettes of the epiphytic tank bromeliad Guzmania monostachia

Guzmania monostachia is an epiphytic heteroblastic bromeliad that exhibits rosette leaves forming water-holding tanks at maturity. Different portions along its leaf blades can display variable degrees of crassulacean acid metabolism (CAM) up-regulation under drought. Since abscisic acid (ABA) can act as an important long-distance signal, we conducted a joint investigation of ontogenetic and drought impacts on CAM intensity and ABA levels in different leaf groups within the G. monostachia rosette. For this, three groups of leaves were analysed according to their position within the mature-tank rosette (i.e., younger, intermediate, and older leaves) to characterize the general growth patterns and magnitude of drought-modulated CAM expression. CAM activity was evaluated by analysing key molecules in the biochemical machinery of this photosynthetic pathway, while endogenous ABA content was comparatively measured in different portions of each leaf group after seven days under well-watered (control) or drought treatment. The results revealed that G. monostachia shows more uniform morphological characteristics along the leaves when in the atmospheric stage. The drought treatment of mature-tank rosettes generally induced in older leaves a more severe water loss, followed by the lowest CAM activity and a higher increase in ABA levels, while younger leaves showed an opposite response. Therefore, leaf groups at distinct ontogenetic stages within the tank rosette of G. monostachia responded to drought with variable degrees of water loss and CAM expression. ABA seems to participate in this tissue-compartmented response as a long-distance signalling molecule, transmitting the drought-induced signals originated in older leaves towards the younger ones.

Postharvest physiology and technology of loquat (Eriobotrya japonica Lindl.) fruit

Loquat (Eriobotrya japonica Lindl.) is a subtropical evergreen tree whose fruit is consumed both fresh and processed. Loquat fruit is a good source of minerals and carotenoids, while the kernel is rich in protein and carbohydrates. It has been considered a non-climacteric fruit, but there is evidence that some cultivars have a ripening pattern similar to that of climacteric fruits. The fruit has a short postharvest life at ambient temperatures and is susceptible to physical and mechanical damage, loss of moisture and nutrients, and decay. Low-temperature storage extends the shelf life of loquat fruit, but some cultivars are severely affected by chilling injury and flesh browning during cold storage. Purple spot, browning and leatheriness are major postharvest disorders. The shelf life of loquat can be extended by modified or controlled atmosphere storage as well as by postharvest treatment with 1-methyl cyclopropene or methyl jasmonate.

Spatial division of phosphoenolpyruvate carboxylase and nitrate reductase activity and its regulation by cytokinins in CAM-induced leaves of Guzmania monostachia (Bromeliaceae)

Crassulacean acid metabolism (CAM) is a physiological adaptation of plants that live in stress environment conditions. A good model of CAM modulation is the epiphytic bromeliad, Guzmania monostachia, which switches between two photosynthetic pathways (C3-CAM) in response to different environmental conditions, such as light stress and water availability. Along the leaf length a gradient of acidity can be observed when G. monostachia plants are kept under water deficiency. Previous studies showed that the apical portions of the leaves present higher expression of CAM, while the basal regions exhibit lower expression of this photosynthetic pathway. The present study has demonstrated that it is possible to induce the CAM pathway in detached leaves of G. monostachia kept under water deficit for 7 d. Also, it was evaluated whether CAM expression can be modulated in detached leaves of Guzmania and whether some spatial separation between NO3(-) reduction and CO2 fixation occurs in basal and apical portions of the leaf. In addition, we analyzed the involvement of endogenous cytokinins (free and ribosylated forms) as possible signal modulating both NO3(-) reduction and CO2 fixation along the leaf blade of this bromeliad. Besides demonstrating a clear spatial and functional separation of carbon and nitrogen metabolism along G. monostachia leaves, the results obtained also indicated a probable negative correlation between endogenous free cytokinins - zeatin (Z) and isopentenyladenine (iP) - concentration and PEPC activity in the apical portions of G. monostachia leaves kept under water deficit. On the other hand, a possible positive correlation between endogenous Z and iP levels and NR activity in basal portions of drought-exposed and control leaves was verified. Together with the observations presented above, results obtained with exogenous cytokinins treatments, strongly suggest that free cytokinins might act as a stimulatory signal involved in NR activity regulation and as a negative regulator of PEPC activity in CAM-induced leaves of G. monostachia during a diel cycle.

Spatial patterns of photosynthesis in thin- and thick-leaved epiphytic orchids: unravelling C3-CAM plasticity in an organ-compartmented way

BACKGROUND AND AIMS

A positive correlation between tissue thickness and crassulacean acid metabolism (CAM) expression has been frequently suggested. Therefore, this study addressed the question of whether water availability modulates photosynthetic plasticity in different organs of two epiphytic orchids with distinct leaf thickness.

METHODS

Tissue morphology and photosynthetic mode (C3 and/or CAM) were examined in leaves, pseudobulbs and roots of a thick-leaved (Cattleya walkeriana) and a thin-leaved (Oncidium 'Aloha') epiphytic orchid. Morphological features were studied comparing the drought-induced physiological responses observed in each organ after 30 d of either drought or well-watered treatments.

KEY RESULTS

Cattleya walkeriana, which is considered a constitutive CAM orchid, displayed a clear drought-induced up-regulation of CAM in its thick leaves but not in its non-leaf organs (pseudobulbs and roots). The set of morphological traits of Cattleya leaves suggested the drought-inducible CAM up-regulation as a possible mechanism of increasing water-use efficiency and carbon economy. Conversely, although belonging to an orchid genus classically considered as performing C3 photosynthesis, Oncidium 'Aloha' under drought seemed to express facultative CAM in its roots and pseudobulbs but not in its leaves, indicating that such photosynthetic responses might compensate for the lack of capacity to perform CAM in its thin leaves. Morphological features of Oncidium leaves also indicated lower efficiency in preventing water and CO2 losses, while aerenchyma ducts connecting pseudobulbs and leaves suggested a compartmentalized mechanism of nighttime carboxylation via phosphoenolpyruvate carboxylase (PEPC) (pseudobulbs) and daytime carboxylation via Rubisco (leaves) in drought-exposed Oncidium plants.

CONCLUSIONS

Water availability modulated CAM expression in an organ-compartmented manner in both orchids studied. As distinct regions of the same orchid could perform different photosynthetic pathways and variable degrees of CAM expression depending on the water availability, more attention should be addressed to this in future studies concerning the abundance of CAM plants.

Effects of brassinosteroid analogues on total phenols, antioxidant activity, sugars, organic acids and yield of field grown endive (Cichorium endivia L.)

BACKGROUND

Cichorium endivia L., either cooked or eaten raw in salads, is a favourite cultivated vegetable around the world and the popularity is attributed to its healthy properties, which are mainly due to its high levels of antioxidant compounds and high content of minerals, provitamin A and vitamins. Brassinosteroids are a family of hormones that are found in plants and which serve as potent growth promoters. The effects of two brassinosteroid analogues, DI-31 and DI-100, were evaluated at concentrations of 4, 8 and 12 ppm together with a seaweed extract and amino acid mixture called Tomex Amin to enhance their activity.

RESULTS

All treatments with DI-100 and DI-31 resulted in the highest production increases. The chemical variables related to endive quality, such as moisture, carbon and nitrogen content, sugar and organic acid content were similar in the control and treated endives. Total antioxidant activity and total phenols increased significantly in endive treated with brassinosteroid analogues.

CONCLUSION

The results showed that sprayed brassinosteroid analogues mixed with Tomex Amin may play an important role in increasing the yield and the contents of total antioxidant activity and total phenols of field grown endives.

Effects of latitude and weather conditions on contents of sugars, fruit acids, and ascorbic acid in black currant (Ribes nigrum L.) juice

The genetic background determined the composition of black currants and the compositional response to weather conditions. The variety Melalahti had higher values for glucose and sugar/acid ratio and lower contents of fructose, citric acid, quinic acid, and vitamin C than the varieties Mortti and Ola (p<0.05). In comparison to black currants grown in northern Finland (latitude 66 degrees 34' N), the berries grown in southern Finland (latitude 60 degrees 23' N) had higher contents of fructose, glucose, sucrose, and citric acid (by 8.8, 6.1, 10.0, and 11.7%, respectively) and lower contents of malic acid, quinic acid, and vitamin C (by 31.1, 23.9, and 12.6%) (p<0.05). Fructose, glucose, and citric acid in Melalahti were not influenced by the weather, whereas their concentrations in Mortti and Ola correlated positively with the average temperature in February (Pearson's correlation coefficients = 0.53-0.79, p<0.01) and July (Pearson's correlation coefficients = 0.63-0.87, p<0.01) and negatively with the percentage of the days with a relative humidity of 10-30% from the start of the growth season until the day of harvest (Pearson's correlation coefficients = from -0.47 to -0.76, p<0.01). Positive correlations existed between fructose and glucose (Pearson's correlation coefficients = 0.95-0.96, p<0.01), citric acid and fructose (Pearson's correlation coefficients = 0.57-0.75, p<0.01), as well as between citric acid and glucose (Pearson's correlation coefficients = 0.56-0.70, p<0.01) in the three varieties because of the closely related metabolic pathways.

Organic Acids and Soluble Sugars in Edible and Nonedible Parts of Damson Plum (Prunus domestica L. subsp. insititia cv. Syriaca) Fruits During Development and Ripening

The contribution of the seed and pericarp to the content of malic, quinic, citric and fumaric acids, and sucrose, fructose and glucose was determined during development and ripening of damson plum fruits. In whole fruit, (i) malic and quinic acids were the principal organic acids (OA) and their levels varied significantly, the highest being found at the beginning of the late-green stage; and (ii) the content of citric and fumaric acids was scarce but fluctuated remarkably towards development and ripening. In the seed, the levels of malic, quinic and fumaric acid were lower in ripening than at the beginning of maturation, and a notable synthesis of citric was found from the middle of maturation onwards. In mesocarp, however, malic, quinic, and citric acids peaked in the middle of maturation, whereas fumaric acid notably increased towards ripening. In epicarp, the maximum for the quinic and malic was found at the beginning of ripening and maturation, respectively. In the seed, all soluble sugars (SS) studied peaked at the middle of maturation, and while fructose and glucose (the most abundant SS) tended to be stored during ripening, sucrose (the most abundant in the edible part of fruit) decreased. All the SS studied tend to increase in mesocarp and epicarp throughout maturation and ripening.

Use of Modified Atmosphere Packaging with Microperforated Polypropylene Films to Maintain Postharvest Loquat Fruit Quality

Loquat fruits (Eriobotrya japonica Lindl cv. `Algerie') were stored in modified atmosphere packaging (MAP), using five types of microperforated polypropylene (PP) films during 2, 4, and 6 weeks at 2 °C and for a subsequent period of 4 days at 20 °C shelf life (SL) out of the bags. Loquat fruits stored without packaging and in normal air served as control. The atmosphere composition at the steady state depended on the film permeability, ranging from 1.2 to 8.5 kPa for CO2 and from 19.5 to 13 kPa for O2 as film permeability decreased. Weight loss was drastically reduced by MAP conditions. Softening, color evolution, and decreases in sugars and organic acids were delayed, these effects also being evident after the SL period. Scores for visual aspect and facility of peeling were also higher for loquat stored in MAP than for controls. Taking into account results form all quality parameters, the most suitable atmosphere for loquat storage was found to be around 2—4 and 16—18 kPa for CO2 and O2, respectively, reached in the PA-80 and PA-60 films. In addition, the storage period for optimum loquat quality maintenance was established as 2 weeks of cold storage plus SL for control fruits, while under MAP conditions, storage periods could be extended up to 6 weeks plus SL, especially using PA-80 and PA-60 films.

Chemical constituents and antioxidant activity of sweet cherry at different ripening stages

The development and ripening process of sweet cherry (Prunus avium L. cv. 4-70) on the tree was evaluated. For this purpose, 14 different stages were selected in accordance with homogeneous size and color. Some parameters related to fruit quality, such as color, texture, sugars, organic acids, total antioxidant activity, total phenolic compounds, anthocyanins, and ascorbic acid were analyzed. The results revealed that in sweet cherry, the changes in skin color, glucose and fructose accumulation, and softening process are initiated at early developmental stages, coinciding with the fast increase in fruit size. Also, the decrease in color parameter a was correlated with the greatest accumulation of total anthocyanins. Ascorbic acid, total antioxidant activity (TAA), and total phenolic compounds decreased during the early stages of sweet cherry development but exponentially increased from stage 8, which coincided with the anthocyanin accumulation and fruit darkening. TAA showed positive correlations (r(2) = 0.99) with both ascorbic acid and total phenolic compounds and also with the anthocyanin concentration from stage 8. Taking into account the reduced shelf life of sweet cherry and to ensure that these fruits reach consumers with the maximum organoleptic, nutritional, and functional properties, it is advisable to harvest sweet cherries at stage 12 of ripening.