Carotenoids, Vitamin C, and Antioxidant Capacity in the Peel of Mandarin Fruit in Relation to the Susceptibility to Chilling Injury during Postharvest Cold Storage

Biomarkers of the main nutritional components in purple rice during five successive grain filling stages

Differences in main nutritional components in relation to biomarkers of metabolites in purple rice grains at different fillings stages have not been determined previously. This study measured the contents of amino acids, several nutritional indicators, and mineral elements in purple rice grains at five stages following the filling stage. The results revealed that the amino acid, ascorbic acid, total sugar, carotenoid, vitamin B9, cyanidin-3-O-glucoside, peonidin 3-glucoside and seven minerals were highest in the final stage of grain filling. Citric acid, L-isoleucine, trigonelline, and L-glutamate are key metabolites in the metabolic pathway and exhibit strong correlations with various nutritional indicators. Hence, this research preliminarily suggested that trigonelline, L-isoleucine, L-glutamate, and citric acid could be potential biomarkers of nutritional components in purple rice grains during various postfilling stages.

Vitamin C variation in citrus in response to genotypes, storage temperatures, and storage times: A systematic review and meta-analysis

Numerous published studies have highlighted discrepancies in the duration and storage temperature used for preserving vitamin C content on various citrus genotypes worldwide. The present study aimed to analyze the variation in vitamin C content as influenced by citrus genotype, duration, and storage temperature using meta-analysis approaches. Data searching, selection, and tabulation resulted in a comprehensive database constructed from 1412 data points gathered from 54 individual studies, following PRISMA-P guidelines. The vitamin C content varied widely, ranging from 0 to 76.2 mg/100 mL in whole data of citrus fruit. Meta-analysis findings revealed that the duration of storage significantly impacted the vitamin C content in citrus fruits. Specifically, for grapefruit, mandarin, and orange, the length of storage significantly influenced their vitamin C levels (P < 0.01), with a consistent decrease observed over time. The correlation coefficients (R2) were 0.63 for grapefruit, 0.9 for mandarin, and 0.69 for orange. In contrast, no significant difference was found in terms of vitamin C levels between hybrid and lime citrus concerning the impact of storage time. However, other results indicated a significant influence of storage temperature on the variation in vitamin C levels for both citrus and hybrid varieties (P < 0.001). Depending on the genotype, tangerine had significantly lower vitamin C content compared to other varieties, at 16.9 mg/100 mL, with vitamin C ranging from 13.2 to 20.9 mg/100 mL (P < 0.001). The highest vitamin C content was found in lemon and hybrid varieties, around 65.5 (range 59.3-76.2) and 48.3 (range 29.6-75.5), respectively, all in mg/100 mL (P < 0.001). Furthermore, there was a tendency for decreasing vitamin C concentration due to temperature (P = 0.078), while citrus variety experienced a decrease, although not significant. The ideal temperature (15 °C) and duration of storage (56 days) to minimize vitamin C loss in citrus fruits are at their optimum point. In conclusion, the deterioration of vitamin C in citrus fruits is influenced by both temperature and storage duration, and its content is also impacted by the variety of citrus.

Sweet cherry TCP gene family analysis reveals potential functions of PavTCP1, PavTCP2 and PavTCP3 in fruit light responses

BACKGROUND

TCP proteins are plant specific transcription factors that play important roles in plant growth and development. Despite the known significance of these transcription factors in general plant development, their specific role in fruit growth remains largely uncharted. Therefore, this study explores the potential role of TCP transcription factors in the growth and development of sweet cherry fruits.

RESULTS

Thirteen members of the PavTCP family were identified within the sweet cherry plant, with two, PavTCP1 and PavTCP4, found to contain potential target sites for Pav-miR159, Pav-miR139a, and Pav-miR139b-3p. Analyses of cis-acting elements and Arabidopsis homology prediction analyses that the PavTCP family comprises many light-responsive elements. Homologs of PavTCP1 and PavTCP3 in Arabidopsis TCP proteins were found to be crucial to light responses. Shading experiments showed distinct correlation patterns between PavTCP1, 2, and 3 and total anthocyanins, soluble sugars, and soluble solids in sweet cherry fruits. These observations suggest that these genes may contribute significantly to sweet cherry light responses. In particular, PavTCP1 could play a key role, potentially mediated through Pav-miR159, Pav-miR139a, and Pav-miR139b-3p.

CONCLUSION

This study is the first to unveil the potential function of TCP transcription factors in the light responses of sweet cherry fruits, paving the way for future investigations into the role of this transcription factor family in plant fruit development.

Antioxidant Interactions between Citrus Fruit Carotenoids and Ascorbic Acid in New Models of Animal Cell Membranes

The regular consumption of citrus fruits by humans has been associated with lower incidence of chronic-degenerative diseases, especially those mediated by free radicals. Most of the health-promoting properties of citrus fruits derive from their antioxidant content of carotenoids and ascorbic acid (ASC). In the current work we have investigated the scavenging (against hydroxyl radical) and quenching capacities (against singlet oxygen) of four different carotenoid extracts of citrus fruits in the presence or absence of ASC (μM range) in organic solvent, aqueous solution, micelles and in an innovative biomimicking liposomal system of animal cell membrane (AML). The fruits of four varieties of citrus were selected for their distinctive carotenoid composition (liquid chromatography characterization): 'Nadorcott' mandarin and the sweet oranges 'Valencia late', 'Ruby Valencia' and 'Pinalate' mutant. The quenching activity of citrus carotenoids strongly depended on the biological assemblage: freely diffusible in organic solvent, 'Ruby Valencia' carotenoids (containing lycopene) showed the highest quenching activity, whereas 'Nadorcott' mandarin extracts, rich in β-cryptoxanthin, prevailed in micellar systems. Interestingly, the addition of 10 μM ASC significantly increased the quenching activity of all citrus extracts in micelles: 'Valencia' orange (+53%), 'Pinalate' (+87%), 'Ruby' (4-fold higher) and 'Nadorcott' mandarins (+20%). Accurate C11-BODIPY581/591 fluorescence assays showed solid scavenging activities of all citrus extracts against AML oxidation: 'Valencia' (-61%), 'Pinalate' (-58%) and 'Ruby' oranges (-29%), and 'Nadorcott' mandarins (-70%). Indeed, all four citrus extracts tested here have balanced antioxidant properties; extracts from the 'Nadorcott' mandarin slightly prevailed overall, due, at least in part, to its high content of β-cryptoxanthin. This study depicts some of the antioxidant interactions between citrus fruit carotenoids and ascorbic acid in models of animal cell membranes and reinforces the contribution of them in promoting health benefits for humans.

Relationship among Sugars, Organic Acids, Mineral Composition, and Chilling Injury Sensitivity on Six Pomegranate Cultivars Stored at 2 °C

Pomegranate is a sensitive fruit to chilling injury (CI) during storage at temperatures below 7 °C. However, sensitivity of pomegranate to CI is dependent on cultivar and exposure times to low temperatures. In this work, the sensitivity to CI of six pomegranate cultivars (Punica granatum L.) 'Wonderful', 'Kingdom', 'Bigful', 'Acco', 'Purple Queen', and 'Mollar de Elche', was evaluated after 30 d at 2 °C plus 2 d at 20 °C. Among cultivars, there was a great variability in the sensitivity to the appearance of CI symptoms. 'Kingdom' cultivar was the most CI sensitive and 'Mollar de Elche' cultivar was the least sensitive cultivar. CI symptoms were greater in the internal part of the skin than in the external part, although no correlation was found between ion leakage (IL) and CI severity after cold storage. However, both, external and internal CI index were correlated with the IL at harvest, with Pearson correlation of 0.63 and 0.80, respectively. In addition, this variability to CI among cultivars could also be due to composition and tissue structures in arils and peel. The solute content of the arils (anthocyanins, sugars, and organic acids, in particular citric acid), showed high correlations with CI sensitivity, with Pearson correlations (r) of 0.56 for total soluble solids, 0.87 for total acidity, 0.94 for anthocyanins, -0.94 for oxalic acid, 0.87 for citric acid, 0.62 for tartaric acid, -0.91 for malic acid, 0.8 for sucrose, and 0.71 for glucose, which can leak to the inner surface of the peel causing browning reactions. In addition, the high peel Ca/K ratio could play an important role on increasing fruit tolerance to CI, since it was negatively correlated with the internal and external CI indexes.

Bioactive Compounds of Shrimp Shell Waste from Palaemon serratus and Palaemon varians from Portuguese Coast

The production and consumption of shrimp species create massive amounts of shrimp bio-waste. In this study, shrimp shell waste from Palaemon serratus and Palaemon varians from the Portuguese coast was characterized. Regarding the antioxidant capacity, the obtained values were between 4.7 and 10.4 mg gallic acid equivalents (GAE)/g dry weight (dw) for Total phenolic content (TPC); 3 and 7 mg ascorbic acid equivalents (AAE)/g dw for Ferric reducing antioxidant power assay (FRAP); 0.4 and 1.2 mg Trolox equivalent (TE)/g dw for 2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical scavenging (DPPH^•); 4 and 11 mg TE/g dw for 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity (ABTS^•+); and 72 and 130 mg TE/g dw for Oxygen radical absorbance capacity (ORAC). For the antimicrobial activity, shrimp shell waste from P. varians formed inhibition zones between 14 and 23 mm. Total carotenoid content values were in the range of 28 and 134 μg/g dw, and according to their HPLC-PAD profile, β-carotene and astaxanthin contents were between 0.3 and 7.6 μg/g dw and 1.1 and 26.1 μg/g dw, respectively. These studies are critical to recognizing the potential added value of shrimp shell waste as possible colorants and preservatives with antioxidant protection capacity to be used in the food industry.

Postharvest Treatment with Abscisic Acid Alleviates Chilling Injury in Zucchini Fruit by Regulating Phenolic Metabolism and Non-Enzymatic Antioxidant System

Reports show that phytohormone abscisic acid (ABA) is involved in reducing zucchini postharvest chilling injury. During the storage of harvested fruit at low temperatures, chilling injury symptoms were associated with cell damage through the production of reactive oxygen species. In this work, we have studied the importance of different non-enzymatic antioxidants on tolerance to cold stress in zucchini fruit treated with ABA. The application of ABA increases the antioxidant capacity of zucchini fruit during storage through the accumulation of ascorbate, carotenoids and polyphenolic compounds. The quantification of specific phenols was performed by UPLC/MS-MS, observing that exogenous ABA mainly activated the production of flavonoids. The rise in all these non-enzymatic antioxidants due to ABA correlates with a reduction in oxidative stress in treated fruit during cold stress. The results showed that the ABA mainly induces antioxidant metabolism during the first day of exposure to low temperatures, and this response is key to avoiding the occurrence of chilling injury. This work suggests an important protective role of non-enzymatic antioxidants and polyphenolic metabolism in the prevention of chilling injury in zucchini fruit.

Juices and By-Products of Red-Fleshed Sweet Oranges: Assessment of Bioactive and Nutritional Compounds

The content of nutrients and bioactive compounds, and antioxidant capacity were assessed in the juices from two red-fleshed oranges, Cara Cara and Kirkwood, and compared with that of a standard Navel orange. Two juice extraction procedures, hand-squeezing and industrial, and two treatments, pasteurization (85 °C/30 s) and high-pressure homogenization (HPH, 150 MPa/55 °C/1 min), were evaluated. For most of the nutrients and bioactive compounds, the hand and industrial juice squeezing rendered similar extraction efficiency. Individual composition of carotenoids in the juices were differentially affected by the extraction procedure and the treatments, but the red-fleshed orange juices contained between 3- to 6-times higher total carotenoids than the standard Navel juices, being phytoene and phytofluene the main carotenoids. The industrial and treated juices of both red-fleshed oranges contained 20-30% higher amounts of tocopherols but about 20% lower levels of vitamin C than Navel juices. Navel juices exhibited higher hydrophilic antioxidant capacity, while the red-fleshed orange juices showed an improved lipophilic antioxidant capacity. The main distinctive characteristic of the industrial juice by-product of the red-fleshed oranges was a higher content of carotenoids (×10) and singlet oxygen antioxidant capacity (×1.5-2) than the Navel by-product.

Citrus By-Products: Valuable Source of Bioactive Compounds for Food Applications

Citrus production produces about 15 million tons of by-products/waste worldwide every year. Due to their high content of bioactive compounds, several extraction techniques can be applied to obtain extracts rich in valuable compounds and further application into food applications. Distillation and solvent extraction continues to be the most used and applied extraction techniques, followed by newer techniques such as microwave-assisted extraction and pulsed electric field extraction. Although the composition of these extracts and essential oils directly depends on the edaphoclimatic conditions to which the fruit/plant was exposed, the main active compounds are D-limonene, carotenoids, and carbohydrates. Pectin, one of the most abundant carbohydrates present in Citrus peels, can be used as a biodegradable polymer to develop new food packaging, and the extracted bioactive compounds can be easily added directly or indirectly to foods to increase their shelf-life. One of the applications is their incorporation in active food packaging for microbiological and/or oxidation inhibition, prolonging foods' shelf-life and, consequently, contributing to reducing food spoilage. This review highlights some of the most used and effective extraction techniques and the application of the obtained essential oils and extracts directly or indirectly (through active packaging) to foods.

Physio-biochemical and molecular stress regulators and their crosstalk for low-temperature stress responses in fruit crops: A review

Low-temperature stress (LTS) drastically affects vegetative and reproductive growth in fruit crops leading to a gross reduction in the yield and loss in product quality. Among the fruit crops, temperate fruits, during the period of evolution, have developed the mechanism of tolerance, i.e., adaptive capability to chilling and freezing when exposed to LTS. However, tropical and sub-tropical fruit crops are most vulnerable to LTS. As a result, fruit crops respond to LTS by inducing the expression of LTS related genes, which is for climatic acclimatization. The activation of the stress-responsive gene leads to changes in physiological and biochemical mechanisms such as photosynthesis, chlorophyll biosynthesis, respiration, membrane composition changes, alteration in protein synthesis, increased antioxidant activity, altered levels of metabolites, and signaling pathways that enhance their tolerance/resistance and alleviate the damage caused due to LTS and chilling injury. The gene induction mechanism has been investigated extensively in the model crop Arabidopsis and several winter kinds of cereal. The ICE1 (inducer of C-repeat binding factor expression 1) and the CBF (C-repeat binding factor) transcriptional cascade are involved in transcriptional control. The functions of various CBFs and aquaporin genes were well studied in crop plants and their role in multiple stresses including cold stresses is deciphered. In addition, tissue nutrients and plant growth regulators like ABA, ethylene, jasmonic acid etc., also play a significant role in alleviating the LTS and chilling injury in fruit crops. However, these physiological, biochemical and molecular understanding of LTS tolerance/resistance are restricted to few of the temperate and tropical fruit crops. Therefore, a better understanding of cold tolerance's underlying physio-biochemical and molecular components in fruit crops is required under open and simulated LTS. The understanding of LTS tolerance/resistance mechanism will lay the foundation for tailoring the novel fruit genotypes for successful crop production under erratic weather conditions.

Growth Temperature Influences Postharvest Quality and Cold Tolerance of Green Harvested Dwarf Tomatoes During Storage

Effect of cultivation temperature during the phase of flowering and fruit development on tomato quality was investigated. Plants of two dwarf tomato cultivars “Ponchi Re” and “Tarzan,” were subjected to three different growth temperatures: 16, 22, or 28°C, starting at the flowering phase. Mature green fruit was harvested and subjected to shelf life at 20°C for 20 days or first stored at 4°C for 15 days, and then placed under shelf life conditions. Fruit quality was determined through red color development, soluble solid content (SSC), softening, weight loss, and cold tolerance. Higher cultivation temperature increased development and production of fruit. Deviation from the 22°C growth temperature led to increased soluble solid content in both cultivars, and smaller fruit diameter in “Tarzan.” Fruit grown at lower temperature had delayed color development during shelf life, and this was further delayed by prior cold storage. “Tarzan” showed more chilling injury (CI) symptoms than “Ponchi Re.” In our experiment, SSC can be manipulated by modulating cultivation temperature, but that it is not associated with CI tolerance. Delayed color formation at the lowest growth temperature observed in “Ponchi Re” tomatoes could be resulted in lower lycopene levels leads to lower ROS scavenging capacity. For “Tarzan” tomatoes, higher firmness at harvest, less softening, and lower weight loss during cold storage in fruit from the lowest cultivation temperature might positively correlated with increased membrane integrity, resulting in increased CI tolerance. This indicates that CI incidence depends on growth temperature and is cultivar dependent in dwarf tomato fruit.

Influence of Climate Change on Metabolism and Biological Characteristics in Perennial Woody Fruit Crops in the Mediterranean Environment

The changes in the state of the climate have a high impact on perennial fruit crops thus threatening food availability. Indeed, climatic factors affect several plant aspects, such as phenological stages, physiological processes, disease-pest frequency, yield, and qualitative composition of the plant tissues and derived products. To mitigate the effects of climatic parameters variability, plants implement several strategies of defense, by changing phenological trends, altering physiology, increasing carbon sequestration, and metabolites synthesis. This review was divided into two sections. The first provides data on climate change in the last years and a general consideration on their impact, mitigation, and resilience in the production of food crops. The second section reviews the consequences of climate change on the industry of two woody fruit crops models (evergreen and deciduous trees). The research focused on, citrus, olive, and loquat as evergreen trees examples; while grape, apple, pear, cherry, apricot, almond, peach, kiwi, fig, and persimmon as deciduous species. Perennial fruit crops originated by a complex of decisions valuable in a long period and involving economic and technical problems that farmers may quickly change in the case of annual crops. However, the low flexibility of woody crops is balanced by resilience in the long-life cycle.

An overview of the nutritional value, health properties, and future challenges of Chinese bayberry

Chinese bayberry (CB) is among the most popular and valuable fruits in China owing to its attractive color and unique sweet/sour taste. Recent studies have highlighted the nutritional value and health-related benefits of CB. CB has special biological characteristics of evergreen, special aroma, dioecious, nodulation, nitrogen fixation. Moreover, the fruits, leaves, and bark of CB plants harbor a number of bioactive compounds including proanthocyanidins, flavonoids, vitamin C, phenolic acids, and anthocyanins that have been linked to the anti-cancer, anti-oxidant, anti-inflammatory, anti-obesity, anti-diabetic, and neuroprotective properties and to the treatment of cardiovascular and cerebrovascular diseases. The CB fruits have been used to produce a range of products: beverages, foods, and washing supplies. Future CB-related product development is thus expected to further leverage the health-promoting potential of this valuable ecological resource. The present review provides an overview of the botanical characteristics, processing, nutritional value, health-related properties, and applications of CB in order to provide a foundation for further research and development.

Effect of fruit shading and cold storage on tocopherol biosynthesis and its involvement in the susceptibility of Star Ruby grapefruit to chilling injury

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Tocopherol content in the flavedo of grapefruit increase during fruit maturation.

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TAT1 and genes of the tocopherol-core pathway are up-regulated during fruit maturation.

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Light avoidance reduces γ-tocopherol and expression of GGDR and tocopherol-core pathway genes.

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Cold up-regulated genes involved in precursors supply but repressed those of the core pathway.

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Changes in tocopherols during storage appears to be cold-mediated and not related to CI tolerance.

The aim of this study was to investigate the role of tocopherols in the susceptibility of Star Ruby grapefruit to postharvest chilling injury (CI). Fruit exposed to normal sunlight (NC, non-covered) and deprived of light (C, covered) in the last stages of development were used. Tocopherol contents increased in the flavedo of both NC and C fruit during development, concomitantly with the up-regulation of TAT1 and most genes of the tocopherol-core pathway. Fruit shading reduced total contents by repressing γ-tocopherol accumulation, associated to a down-regulation of GGDR and VTE1 and, to a lesser extent, of VTE2, VTE3a and VTE4. During cold storage, total and α-tocopherol contents increased in NC and C fruit, and no direct relationship between tocopherol accumulation and CI tolerance was found. Cold stress up-regulated most genes involved in the synthesis of tocopherol precursors and down-regulated those of the tocopherol-core pathway, but changes seemed to be cold-mediated and not related to CI development.

Prediction and Chemical Interpretation of Singlet-Oxygen-Scavenging Activity of Small Molecule Compounds by Using Machine Learning

A chemically explainable machine learning model was constructed with a small dataset to quantitatively predict the singlet-oxygen-scavenging ability. In this model, ensemble learning based on decision trees resulted in high accuracy. For explanatory variables, molecular descriptors by computational chemistry and Morgan fingerprints were used for achieving high accuracy and simple prediction. The singlet-oxygen-scavenging mechanism was explained by the feature importance obtained from machine learning outputs. The results are consistent with conventional chemical knowledge. The use of machine learning and reduction in the number of measurements for screening high-antioxidant-capacity compounds can considerably improve prediction accuracy and efficiency.

Carotenoids and Apocarotenoids in Planta: Their Role in Plant Development, Contribution to the Flavour and Aroma of Fruits and Flowers, and Their Nutraceutical Benefits

Carotenoids and apocarotenoids are diverse classes of compounds found in nature and are important natural pigments, nutraceuticals and flavour/aroma molecules. Improving the quality of crops is important for providing micronutrients to remote communities where dietary variation is often limited. Carotenoids have also been shown to have a significant impact on a number of human diseases, improving the survival rates of some cancers and slowing the progression of neurological illnesses. Furthermore, carotenoid-derived compounds can impact the flavour and aroma of crops and vegetables and are the origin of important developmental, as well as plant resistance compounds required for defence. In this review, we discuss the current research being undertaken to increase carotenoid content in plants and research the benefits to human health and the role of carotenoid derived volatiles on flavour and aroma of fruits and vegetables.

Evaluation of the Health-Promoting Properties of Selected Fruits

In this study, the health-promoting benefits of different fruits grown in Madeira Island, namely lemon (Citrus limon var. eureka), tangerine (Citrus reticulata var. setubalense), pitanga (Eugenia uniflora var. red), tomato (Solanum lycopersicum var. gordal) and uva-da-serra, an endemic blueberry (Vaccinium padifolium Sm.), were investigated. The phenolic composition (total phenolics and total flavonoids content) and antioxidant capacity (assessed through ABTS and DPPH assays) were measured revealing a high phenolic potential for all fruits, except tomato, while uva-da-serra is particularly rich in flavonoids. In relation to the antioxidant capacity, the highest values were obtained for pitanga and uva-da-serra extracts. The bioactive potential was also assessed through the ability of the extracts to inhibit digestive enzymes linked to diabetes (α-amylase, α- and β-glucosidases) and hypertension (angiotensin-converting enzyme, ACE). The results obtained point to a very high bioactive potential with the selected samples exhibiting very important ACE anti-enzymatic capacities. A statistical analysis of the obtained data reveals a very strong correlation between ABTS and TPC, and a strong contribution of the fruit polyphenols for enzyme inhibition, and thus, presenting high antihypertensive and antidiabetic capacities. Overall, the results obtained clearly show a high bioactive potential of the selected fruits that should be further studied, in terms of specific phenolic composition. Moreover, these results strongly support the valorisation of pitanga seeds usually discarded as a waste, and uva-da-serra, an endemic and wild bush, as potential bioresources of bioactive compounds with impact in human diet.

Valorization of Citrus Co-Products: Recovery of Bioactive Compounds and Application in Meat and Meat Products

Citrus fruits (orange, lemon, mandarin, and grapefruit) are one of the most extensively cultivated crops. Actually, fresh consumption far exceeds the demand and, subsequently, a great volume of the production is destined for the citrus-processing industries, which produce a huge quantity of co-products. These co-products, without proper treatment and disposal, might cause severe environmental problems. The co-products obtained from the citrus industry may be considered a very important source of high-added-value bioactive compounds that could be used in the pharmaceutical, cosmetic, and dietetic industries, and mainly in the food industry. Due to consumer demands, the food industry is exploring a new and economical source of bioactive compounds to develop novel foods with healthy properties. Thus, the aim of this review is to describe the possible benefits of citrus co-products as a source of bioactive compounds and their applications in the development of healthier meat and meat products.