Antioxidant Capacity Of Fruits Research Articles

Effect of microbial biostimulants on the antioxidant profile, antioxidant capacity and activity of enzymes influencing the quality level of raspberries (Rubus idaeus L.)

The influence of four microbial biostimulants containing various strains of Bacillus subtilis and/or Paenibacillus sp. on the quality of raspberries cv. Delniwa, Poemat, and Enrosadira cultivated in two consecutive seasons was investigated. The biostimulants influenced the antioxidant level, antioxidant capacity, phenolic acids and flavonoids profiles, enzymatic activity, and the degree of methylation and acetylation of the pectin in the raspberry fruits. The biostimulants had the greatest effect on the antioxidant content (16% - 20% increase) and capacity in the Delniwa raspberry fruits from the first season. A positive correlation was found between the activity of the β-galactosidase enzyme and ferric reducing power. In the second season, a decrease in the activity of pectin esterase and α-L-arabinofuranosidase and an increase in the degree of methylation of pectin were noted. Our results suggest that the changes in raspberry quality were related to the type of biostimulant applied.

Preharvest Sodium Nitroprusside Application Preserved Antioxidant Capacity and Storage Quality of Plum Fruit

Preharvest Sodium Nitroprusside Application Preserved Antioxidant Capacity and Storage Quality of Plum Fruit

Wide temperature adaptive oxidase-like based on mesoporous manganese based metal-organic framework for detecting total antioxidant capacity

Overcoming the intense variation of enzymatic activity among different temperatures is very critical in catalytic medicine and catalytic biology. Here, Mn-based metal-organic framework-based wide-temperature-adaptive mesoporous artificial enzymes (Mn-TMA-MOF) were designed and synthesized. The oxidase-like Mn-TMA-MOF showed excellent catalytic activity at 0–50 °C and avoided the activity loss and instability due to temperature variation that occurred. The excellent oxidase-like properties of Mn-TMA-MOF with wide temperature adaptativeness are mainly ascribed to the mixed oxidized state (Mn3+/Mn2+) and high substrate affinity (Km = 0.034 mM) of Mn. Moreover, the mesopore-micropores two-level structure of Mn-TMA-MOF provides a large space and surface area for enzyme catalysis. Based on the stability of Mn-TMA-MOF, we developed a colorimetric sensor that can detect total antioxidant capacity in fruits with a limit of detection up to 0.59 μM.

Antioxidant Capacity, Sugar Content, and Tandem HPLC-DAD-ESI/MS Profiling of Phenolic Compounds from Aronia melanocarpa Fruits and Leaves (Nero and Viking Cultivars).

This study examined the phenolic profile, sugar composition, and antioxidant capacities of chokeberry fruits and leaves obtained from four different Turkiye provinces. A total of 21 phenolics including phenolic acid and its derivatives, flavanols, anthocyanins, and flavonols were determined in the fruits, while the leaves had 19 phenolics, including phenolic acid and its derivatives, flavanols, and flavonols. The total amount of phenolic compounds was the highest in both fruits and leaves in the samples from the Bursa province. Cis 5-O-p-coumaroylquinic acid and secoxyloganin were quantified for the first time in both fruits and leaves. In summary, it was found that different geographical locations significantly affected the phenolics, sugar contents, and antioxidant activities of the fruits and leaves.

Diversity of phenolic compounds, antioxidant capacity, and mineral element content in four fig cultivars (Ficus carica L.) and their correlation with the rooting of hardwood cuttings

We investigated the phenolic compound profile, antioxidant capacity, rooting of cutting and fruit mineral concentration on 15-year-old trees of four Iranian figs (Ficus carica cvs. “Siyah”, “Kashki”, “Shahanjir” and “Sabz”) planted under rain-fed conditions with different fruit skin color, as well as the correlation between these traits. The range of TSS and antioxidant capacity of fruit (without significant differences) was 75.3–76.7°Brix and 87.9–90.3 DPPHsc %, respectively. “Kashki” had the highest total phenolic (TP) (mg GAE/100 g dw) in both the fruit (1964) and the stem bark (1702) and “Sabz” had the lowest flavonoid content (µg CE mg−1 dw) in the fruit (652.3), leaf (1274.5), and stem bark (1501.9). Although the rooting percentage of cuttings was similar in “Siyah”, “Shahanjir”, and “Sabz”, the lowest rooting percentage (62.7%) and the lowest polyphenol oxidase enzyme (PPO) activity (42.5 U.mL−1) were in “Kashki”. Rooting of the cuttings had a direct correlation with PPO activity and catechin and a negative correlation with the TP, vanillin and trans-ferulic acid concentration in cutting bark. These results showed that the fresh cultivar such as “Shahanjir” with outstanding characteristics, such as high potassium and antioxidant content of fruits and good rooting of the cuttings (97.2%) can be recommended for the development programs of light-colored fresh figs. On the other hand, there were two cultivars, “Siyah” and “Kashki” with dark fruit color; due to their content of TP, total flavonoid, quercetin, trans-ferulic acid and high calcium content in the fruit, these should also be considered.

Effect of exogenous melatonin on antioxidant properties and fruit softening of 'Fengtang' plum fruit (Prunus salicina Lindl.) during storage at room temperature.

'Fengtang' plums soften quickly and lose flavor after harvest. This study comprehensively evaluated the effect of exogenous melatonin on the fruit quality of 'Fengtang' plums. According to our findings, exogenous melatonin prevented plum fruit from losing water, delayed the decline in firmness, and preserved a high TSS/TA level. Additionally, exogenous melatonin also enhanced the activity of antioxidant enzymes and increased the non-enzymatic antioxidants, thereby further increasing the antioxidant capacity of plum fruit. Notably, exogenous melatonin delayed the degradation of covalent soluble pectin (CSP), cellulose, and hemicellulose, as well as the rise in water-soluble pectin (WSP) concentration and the activity of cell wall degrading enzymes. Further investigation using atomic force microscopy (AFM) revealed that the chain-like structure of ionic-soluble pectin (ISP) and the self-assembly network structures of CSP were depolymerized, and melatonin treatment retarded the depolymerization of pectin structures. Our results showed that exogenous melatonin preserved the postharvest quality of plum fruits by controlling fruit softness and antioxidant capacity during storage.

Ethanol vapor ameliorates chilling injury and maintains postharvest quality by increasing antioxidant capacity of hardy kiwifruit (Actinidia arguta)

Hardy kiwifruit (Actinidia arguta) stored at room temperature has a limited shelf life, and improper low-temperature storage can cause chilling injury. To address this issue, we applied ethanol vapor pre-treatment at concentrations of 250, 500, and 1000 μL L−1 and evaluated postharvest quality under low-temperature conditions (1 ± 1 °C). Our research revealed that lower concentrations of ethanol vapor (250–500 μL L−1) effectively mitigated chilling injury, delayed adverse physiological changes, such as superficial scald, softening, and rot, and enhanced the antioxidant system of A. arguta fruit. Ethanol treatment increased the activity of antioxidant enzymes like peroxidase, superoxide dismutase, and glutathione reductase while maintaining higher levels of non-enzymatic antioxidants like total phenolics, total flavonoids, ascorbic acid, and glutathione. It also improved the antioxidant capacity as assessed by various methods. Principal component analysis and overall scores demonstrated that ethanol vapor treatment significantly improved A. arguta fruit's antioxidant capacity and postharvest quality, extending the optimal consumption period by 14 d. This highlights ethanol's potential application in preserving A. arguta fruit's postharvest quality and enhancing its antioxidant capacity.

Enhancement of antioxidant quality by Bacillus siamensis N-1 and the role of LcPOD4 in regulating peel browning and senescence of litchi fruit

Plant peroxidases (POD) are involved in various physiological and biochemical processes. Currently, there are relatively few studies on the role of POD in regulating the antioxidant capacity and senescence of postharvest litchi. In this study, we assessed the effects of Bacillus siamensis strain N-1 on the physiology and antioxidant quality of litchi fruit stored at 25 ℃, and characterized the molecular function of LcPOD4 gene in regulating the senescence of litchi fruit. The results showed that N-1 treatment significantly suppressed the increase in ethylene production, electrolyte leakage, and malondialdehyde (MDA) but did not inhibit the respiration rate of litchi during storage. Meanwhile, N-1-treated fruit maintained higher levels of phenolics, flavonoids, and total antioxidant capacity (T-AOC) and lower levels of superoxide anions (O2-.) and hydrogen peroxide (H2O2). In addition, N-1 treatment enhanced the activity of defense enzymes, including superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), and phenylalanine ammonia-lyase (PAL). The results of quantitative real-time PCR (qRT-PCR) showed that the expression of nine selected LcPOD genes was induced by N-1 treatment at later stages of litchi storage. LcPOD4 cloned from litchi fruit was located in the cell wall and membrane. Transient overexpression of the LcPOD4 gene in tomato and litchi fruits significantly enhanced POD activity and total phenolic and flavonoid contents while accelerating peel color change in the fruit. Collectively, our results indicate that LcPOD4 may contribute, at least partially, to the enhancement of antioxidant capacity in litchi fruit but does not retard peel browning and senescence.

Effect of melatonin foliar sprays on morphophysiological attributes, fruit yield and quality of Momordica charantia L. under salinity stress

Soil salinity is one of the increasing problems in agricultural fields in many parts of the world, adversely affecting the performance and health of the plants. As a pleiotropic signal and antioxidant molecule in both animals and plants, melatonin has been reported to possess significant roles in combating with stress factors, in general and salt stress, in particular. In this study, the interactive effects of melatonin (0, 75, and 150 μM) and salt stress (0, 50 and 100 mM NaCl) were investigated by assaying the some agronomic, physlogical and biochemical attributes and essential oil compounds of bitter melon (Momordica charantia). The results showed that exogenous melatonin could promote net photosynthetic rate (Pn) and PSII efficiency (Fv/Fm), increase K+ content and activity of antioxidant enzymes and decrease reactive oxygen species, malondialdehyde and Na+ content in stress-submitted seedlings, in comparison to the non-stressed seedlings (p < 0.05). Melatonin increased content of essential oils. Concerning the major compounds of fruits of bitter melon, charantin, momordicin and cucurbitacin were increased with the melatonin treatments, whereas they were critically decreased with the salt stress. In addition, melatonin increased the antioxidant capacity in fruits under non-saline and salinity conditions. Amid the concentrations of melatonin, plants treated with 150 μM of melatonin under either non-saline or saline conditions showed better performance and productivity. Therefore, application of 150 μM melatonin resulted in a significant improvement of salinity tolerance and essential oil compounds in bitter melon plant, suggesting this as an efficient ‘green’ strategy for sustainable crop production under salt stress conditions.

The Phenolic Composition, Antioxidant Activity and Microflora of Wild Elderberry in Asturias (Northern Spain): An Untapped Resource of Great Interest.

The objective of this study is the characterization of the phenolic profile and antioxidant activity of elderberries (Sambucus nigra L.) from a collection of 79 wild specimens in northern Spain to assess variations in the species at the local level and evaluate its interest as a source of biocompounds. Also, a first study was carried out on the microflora present in this fruit, providing information relevant to its commercial exploitation. Moreover, the phenolic composition, antioxidant capacity and microbial composition in overripe fruits were determined, seeking a better use for this currently wasted resource. A wide variability in levels of phenolics was detected. Elderberries showed high antioxidant activity related to a high cyanidin derivative content, making them of interest to industry. Microflorae were present in very variable concentration ranges, so their levels should be monitored in those applications that require strict control. Overripe fruits are of interest as a source of anthocyanidins, since their concentration and antioxidant capacity remain after the optimal ripening period, promoting sustainability and a better use of natural resources. The database generated is of particular interest for further breeding trials based on the phenolic profile and antioxidant activity of the samples.

Bordeaux mixture accelerates ripening, delays senescence, and promotes metabolite accumulation in jujube fruit

Abstract The old, but eco-friendly pesticide, Bordeaux mixture (Bm), is widely used in agriculture. Here, the effects of Bm on preharvest fruit ripening, and postharvest senescence of fruit and the accumulation of antioxidants were studied in Ziziphus jujuba. A 200× dilution of Bm enhanced preharvest ripening and retarded jujube fruit postharvest senescence. Treatment with Bm increased the reddening index and promoted the accumulation of total phenolics (TP) and the total antioxidant capacity (TAC) in preharvest fruit. However, this Bm-accelerated ripening could be partly reversed using dimethylthiourea (DMTU), a specific scavenger of reactive oxygen species. Compared with preharvest fruit, Bm treatment decreased weight loss and decay and increased firmness in postharvest fruit. Similarly, Bm-delayed senescence was partly reversed using dimethylthiourea. Moreover, the decrease in TP and TAC during storage was partly impeded by Bm. A higher H2O2 content was detected in preharvest fruit than in postharvest fruit. Moreover, this Bm-induced H2O2 accumulation was significantly mitigated using dimethylthiourea. Interestingly, both preharvest and postharvest spraying with Bm significantly enhance copper and calcium accumulation in fruit. Thus, Bm can be widely used before or after harvest to improve fruit quality.

Fruits from tomato carotenoid mutants have altered susceptibility to grey mold

The necrotrophic fungus Botritys cinerea takes advantage of the oxidative burst to facilitate tissue infection, leading to substantial losses during tomato postharvest. Tomato fruit is a source of carotenoids, pigments with a wide variety of isomeric configurations that determine their antioxidant capacity. Here, fruit susceptibility to B. cinerea was assessed in Micro-Tom Near Isogenic lines harboring mutations that alter the profile of carotenoids. Wound-inoculated fruit of the mutants Delta carotene (Del) and tangerine (t), which show large variety of carotenoids rather than the major accumulation of trans-lycopene, were less susceptible to the pathogen. Differences in susceptibility between the mutants were only observed in ripe fruit, after the formation of carotenoids, and they were associated with attenuation of damage caused by reactive oxygen species. The greater variety of carotenoid isomers, which in turn contributed to the greater lipophilic antioxidant capacity of fruit, was associated with the less susceptible mutants, Del and t. Together, our data reveals a potential activity of carotenoids in fruit defense, in addition to the well-known and widespread ecological role as attractors of seed dispersers.

Foliar-applied silicon and selenium nanoparticles modulated salinity stress through modifying yield, biochemical attribute, and fatty acid profile of Physalis alkekengiL.

Soil salinity is a major environmental problem owing to its negative impact on agricultural productivity and sustainability. Nanoparticles (NPs) have recently been highlighted for their ability to alleviate salinity stress. The current study aimed to alleviate salt stress by using silicon (Si) and selenium (Se) NPs on the growth and physiological attributes of Physalis alkekengi L. Plants were irrigated with saline water at 50, 100, and 200 mM NaCl, and Si NPs (200 mg L-1) and Se NPs (50 mg L-1) were sprayed on leaves three times in a pot experiment in 2022. Leaf chlorophyll (Chl) content, antioxidant capacity, and fatty acid (FA) profile of fruits were measured to find the effects of NPs and salinity in the plants. Salinity at 50 mM did not significantly differ from the control, but at 100-200 mM, salt stress had a substantial impact on the majority of traits. Compared with non-saline conditions, 200 mM NaCl led to decreases in shoot weight (40%), fruit weight (30%), Chl a (30%), Chl b (39%), anthocyanin (31%), ascorbic acid (16%), total phenolic content (TPC, 11%) but increases in total soluble solids (TSS, 79%), titration acidity (TA, 17%), and TSS/TA (52%) in plants without spraying the NPs. However, Si and Se NPs modulated salinity stress by increasing shoot and fruit weight, Chl content, anthocyanin, and TPC, and with decreasing TSS and TSS/TA. Salinity elevated polyunsaturated fatty acids (PUFAs) and lowered monounsaturated fatty acids (MUFAs). According to multivariate analysis, 50 mM and control were found to be in the same cluster, whereas 100 and 200 mM were shown to be in different clusters. Foliar application of Si and Se NPs at 200 and 50 mg L-1, respectively, can be recommended for mitigating salt stress at 100-200 mM NaCl inP. alkekengiL. Plants. Farmers can use the findings to increase the ability of Si and Se NPs to protect plants against salt.

By-Product from Livestock Waste Recovery System Used as Fertilizer: Bioactive Compounds and Antioxidant Activity of Tomato Fruit as Affected by Fertilization under Field and Greenhouse Conditions

Conversion of livestock manure into organic fertilizer is a sustainable strategy in crop production. In contrast to composted manure, the agronomic characteristics of an anaerobic digestion by-product, digestate, have not been well characterized. This study aimed to investigate the effects of digestate and compost, derived from a pilot-scale livestock waste recycling system, on bioactive compounds in tomato fruits. Both field and greenhouse experiments were conducted to compare the effects of these two organic fertilizers with the application of chemical fertilizer. These comparisons were made by evaluating their influence on tomato yield and bioactive compound contents and antioxidant activity of fruits. The experiment included a control (no fertilizer) and three fertilization treatments with the same nitrogen dose: chemical fertilizer, digestate, and compost. The results revealed that the application of digestate and compost yielded similar results in terms of tomato production, surpassing both the chemical fertilizer application and the control group under both field and greenhouse conditions. Fertilization exhibited a significant influence on the bioactive compound contents and antioxidant capacity of the fruits. Furthermore, the application of digestate and compost led to an increase in the concentration of sugars, phenolic compounds, and several organic acids in the fruits while simultaneously reducing the citric acid levels in comparison to the chemical fertilizer treatment. Moreover, the application of both organic fertilizers improved the total phenol and total flavonoid contents in tomato fruits, and the antioxidant capacity in fruits was significantly higher than that of the chemical fertilizer treatment. In conclusion, the application of digestate or compost derived from the livestock waste recycling system reduced use of chemical fertilizers and resulted in higher tomato yields and fruit with considerably superior bioactive compounds. The results suggested that using digestate or compost as an alternative to inorganic fertilizers for tomato cultivation could assist farmers in increasing productivity, improving the content of bioactive compounds in tomato fruit, and promoting agricultural waste management.

1 H-cyclopropa[b]naphthalene: a novel ethylene antagonist for extending storage life and maintaining quality of climacteric and suppressed climacteric plums

Ethylene is a key trigger that governs the rate of fruit ripening, storability, and postharvest quality of fresh fruit. Efficient inhibition of ethylene action is essential to slow down the postharvest ripening processes, extend storage life and maintain optimum fruit quality during storage. Ethylene antagonist compounds with the likelihood of application as liquid formulation would facilitate managing ethylene broadly as both preharvest and/or postharvest treatments. This study examined the effects of different aqueous formulations of 1 H-cyclopropa[b]naphthalene (NC) as an ethylene antagonist in the cold stored (1 °C) Japanese plums ‘Angeleno’ (suppressed-climacteric) and ‘Tegan Blue’, which exhibit climacteric peaks, respectively. NC was applied as a 2 µM spray solution prepared using only distilled water (NCA), 5% ethanol (NCE), 0.02% Tween® 20 (NCT), 5% β-cyclodextrin (NCD) or a 1 µM fumigant for 18 h at ambient conditions (20 ± 1 °C). Regardless of formulation, NC retarded ethylene production in both the suppressed-climacteric and climactic cultivars. The capacity of NC to suppress ethylene production was relatively higher in ‘Angeleno’ than in ‘Tegan Blue’. Levels of bioactive compounds such as total phenols, total anthocyanins and total antioxidant capacity in fruit treated with NC were at par with the control. NC fumigation was the most effective treatment in suppressing ethylene production and maintaining fruit quality followed by NCE, NCT, NCD and NCA in both plum cultivars. Amongst the NC spray solutions, the ones with ethanol or Tween® 20 as adjuvants outperformed other solutions. Ethylene production positively correlated with weight loss, SSC, SSC: TA and concentrations of individual sugars, but was negatively correlated with firmness, titratable acidity (TA) and individual organic acids in both cultivars. The results also support the notion that ethylene has a role in the synthesis of phenolic compounds and anthocyanin depending on the sugar substrates present in the phenylpropanoid and flavonoid pathways.

Influence of Novel Freezing and Storage Technology on Nutrient Contents, Bioactive Compounds and Antioxidant Capacity of Black Eggplant

The present work aims to study some technological aspects related to the preservation of black eggplant (Solanum melongena L.) fruits by freezing process. Also, the influence of such preservation method on the chemical composition, nutritional value, bioactive compounds content and antioxidant capacity of eggplant fruits will also determine. In fresh eggplant fruits, water is by far the most abundant components with 90.21% of the total fruit weight and fiber is particularly abundant (2.98%). Also, fruits has s moderate levels of vitamins (A, B3, B9, C, E and K) and minerals (P, Mg, Ca, Na, Fe, and Zn) but are relatively rich in K. Phenolics was reported the most abundant bioactive compounds, followed by anthocyanins, flavonoids and β-carotene. The high content of bioactive compounds in the eggplant samples was met with a high level of antioxidant capacities, which was determined by several different methods. The freezing method (slow freezing with grilling pretreatment) that was applied in this study led to cause slightly loses of all studied vitamins by the ratio of ranged -0.88 to -10.97%, and significant (p≤ 0.05) losses of bioactive compounds ratio of ranged -2.52 and -10.23% as compared with the fresh samples, respectively. In contrary, freezing has been shown to cause significant (p≤ 0.05) increase of antioxidant capacities by 4.57 and 11.74% for antioxidant activity and trolox equivalent (TE) assays, as compared with the fresh samples, respectively. Also, prolonging the storage period for six months at -180C did not have a significant effect on all previous measurements. In conclusion, the use of this new and effective method in eggplant preservation may contribute to increasing the economic importance of this product by making it available in the markets regularly throughout the year, easing of export, and increasing the income of the producing countries. How to Cite: Yousif A. Elhassaneen, Ghada M. ElBassouny, Omar A. Emam, Sherouk H. Hashem, 2023. "Influence of Novel Freezing and Storage Technology on Nutrient Contents, Bioactive Compounds and Antioxidant Capacity of Black Eggplant." Journal of Agriculture and Crops, vol. 9, pp. 338-352.

Effect of Different Drying Techniques on Total Bioactive Compounds and Individual Phenolic Composition in Goji Berries

In recent years, interest in the consumption of dried goji berries has increased due to its high bioactive properties. Alternative drying methods that provide faster drying and better preservation of bioactive properties should be developed. This study aims to investigate the effect of different drying methods on the drying time and quality characteristics of the goji berry; namely, hot-air drying (HAD), ultrasound-assisted vacuum drying (USVD), vacuum drying (VD), freeze-drying (FD), and ultrasound-pretreated freeze-drying (USFD). The drying kinetic, total phenolic content, antioxidant capacity, phenolic profile, carotenoid profile, and color change of the goji berry fruit were determined. The drying times for VD, USVD, and HAD varied between 275–1330 min. USVD treatment showed faster drying behavior than the other two drying methods. The total phenolic content (TPC) value of dry samples varied between 1002.53–1238.59 mg GAE/g DM. USVD treatments exhibited a higher total phenolic content (TPC) value than all other drying methods. DPPH and CUPRAC values varied between 15.70–29.90 mg TE/g DM and 40.98–226.09 mg TE/g DM, respectively. The total color change (ΔE) value ranged between 4.59 and 23.93 and HAD dried samples showed the highest ΔE of all samples. The results of the phenolic profile were consistent with TPC analysis. HAD caused higher phenolic compound degradation than VD, USVD, and FD. The results of this study showed that different drying techniques significantly affected the drying rate and retention of bioactive components of the goji berry fruit, and the USVD and VD methods could be used as an alternative to the HAD method. This study concluded that USVD and FD could be considered as suitable drying methods and could be used as alternatives to HAD in the drying of goji berries.

Postharvest Physicochemical Quality Assessment of Greenhouse Produced Soilless Cucumbers in Relation to Differential Fertigation

A study was undertaken to investigate the physico-chemical quality of cucumbers produced in soilless media under naturally ventilated greenhouse microclimatic conditions. The monitored microclimatic parameters included mainly air temperature, relative humidity and solar radiation. The air temperature varied in the range of 19.1-29.3°C and 22.6 32.4°C during season 1 and season 2, respectively. Relative humidity varied in the range of 55.0-91.5% and 59.3-85.3% during season 1 and season 2, respectively. Solar radiation varied in the range of 80-147 W.m-2 and 97-172 W.m-2 during season 1 and season 2, respectively. The quality of cucumber was significantly affected by growing seasons, crop varieties, and fertigation levels. The vitamin C content, total phenolic content, and total chlorophyll content were significantly higher for PBRK-4 variety compared to Kafka and Multistar during both growing seasons, mainly due to varietal differences. Fruit firmness was also highest for PBRK-4 variety for both growing seasons at 100% level of fertigation. The vitamin C content, total phenolic content, antioxidant capacity, chlorophyll content, and firmness of cucumber fruit were in the range of 3.29-5.52 mg.100 g-1, 0.550-1,724 mg.100 g-1, 12.7-21.8%, 117.09-129.97 mg.100 g-1, and 30,960-34,030 gf, respectively. The partially controlled growing conditions helped in improving the physico-chemical quality of cucumber to a great extent compared to open field conditions.

Plastic Covers and Potassium Pre-Harvest Sprays and Their Influence on Antioxidant Properties, Phenolic Profile, and Organic Acids Composition of Sweet Cherry Fruits Cultivated in Southern Chile

In rainy areas, sweet cherries are cultivated under plastic covers, preventing the cracking of the fruit but decreasing the firmness and acidity of the cherries. We evaluated the impact of plastic cover and pre-harvest K foliar application on quality parameters, antioxidant properties, and phenolic and organic acid compositions in fruits of sweet cherry cv. Regina of Southern Chile. Our results showed that K+ increased firmness, total soluble content, size, fruit weight, and titratable acidity at harvest, independent of the cover factor. The positive impacts of foliar K fertilization on anthocyanins, flavonoids, and phenolic acids could explain the higher antioxidant capacity of fruits. Our study revealed that the additional K doses applied increased malic acid, the main organic acid in cherry fruits, but only in fruits from uncovered trees. In covered trees, the effect was reversed. Citric acid was higher in fruit from covered trees. Our results indicated that tartaric acid also increased with the application of higher K doses; however, this acid was detectable only in uncovered tree fruit. Interestingly, all organic acids were lower in fruits produced in the lower canopy than those detected in fruits harvested from the upper canopy. This showed the positive impact of canopy light exposure on maintaining suitable acidity levels in sweet cherry fruits.

Evolution of the Volatile Organic Compounds, Phenols and Antioxidant Capacity during Fruit Ripening and Development of Rubus ulmifolius Schott Fruits

Nowadays, a growing interest in consumers’ fruit with a high content of health-promoting compounds has been observed. In this sense, wild berries have received special attention based on their high accumulation of phenolic compounds, as well as their characteristic and pleasant aroma. In this work, we characterize the color development, antioxidant capacity, phenolic contents, and volatile profile of Rubus ulmifolius Schott fruit at different ripening stages during two seasons on the same orchard. Four stages were established based on the color parameter, which was consistent with changes in the weight and size of the fruit. In addition, total phenolic and flavonoid content showed a decrease during the fruit ripening, in contrast with the total anthocyanins content that increased at the final stages of ripening. In addition, the antioxidant capacity was evaluated through two approaches: FRAP and DPPH, which consistently displayed higher levels at the final stages in the two different seasons. Finally, the VOCs analysis showed an active synthesis of volatile compounds during the late stage of ripening, with alcohols being the most abundant compounds for each ripening stage. These results allow us to propose a classification of different ripening stages of the wild blackberry to have a better knowledge of this interesting fruit with higher healthy- and nutraceutical compounds.