Fruit Content Research Articles

Metabolite quantification data based on 1H-NMR profiling of eggplant or pepper fruit during its development.

The primary metabolite contents of ripe fruits result from complex regulations during their development. For Solanaceae, these regulations have been widely studied in tomato. The fruit metabolite contents of other fruit species, such as pepper (Capsicum annuum L.) and eggplant (Solanum melongena L.), constitute a valuable resource for the community to study the regulation of fruit metabolism and identify common or species-dependent regulations. This dataset about major polar metabolites is part of a larger project that integrates other omics data for pepper and eggplant, and other fruit species for metabolomics and other omics. We provide quantitative metabolite data of pepper and eggplant fruit along development. We sampled pepper and eggplant fruit cultivated in a tunnel or a greenhouse at 10 or 11 stages from anthesis to ripe fruit. We used proton nuclear magnetic resonance (1H-NMR) metabolomic profiling of polar extracts to quantify the major metabolites and expressed the data in µmol per g fresh weight. Twenty-four metabolites were determined in pepper and 27 in eggplant. Nineteen common metabolites were quantified in both fruit species including three soluble sugars and one sugar-alcohol, five organic acids and nine free amino acids. These data can be combined with similar quantitative data on other species or complemented with other omics data to perform cross-species or cross-omics comparisons.

Multi-Omics Analysis Uncovers the Mechanism for Enhanced Organic Acid Accumulation in Peach (Prunus persica L.) Fruit from High-Altitude Areas

The early-ripening peach industry has undergone rapid development in the Panxi region of the Sichuan Basin in recent years. However, after the introduction of some new peach varieties to the high-altitude peach-producing areas in Panxi, the titratable acid content in peach fruit has significantly increased. This study compared the fruit quality indicators of early-ripening peach varieties cultivated in Xide County (a high-altitude peach-producing area) and Longquanyi District (a low-altitude peach-producing area) in Sichuan Province and analyzed the differences in organic acid metabolism by combining primary metabolomic and transcriptomic approaches. The results showed that the ‘Zhongtaohongyu’ fruit from the high-altitude peach-producing area had a much higher accumulation of malic acid and, accordingly, a significantly higher organic acid content than the other samples. The lower annual average temperature and stronger ultraviolet radiation in high-altitude peach-producing areas may lead to the increased expression of genes (PpNAD-ME1, PpNADP-ME3, and PpPEPC1) in the organic acid synthesis pathway and the decreased expression of genes (PpACO2, PpNAD-MDH2/3/4/5, and PpPEPCK2) in the organic acid degradation pathway in peach fruit, ultimately resulting in the accumulation of more organic acids. Among them, the downregulation of the key genes PpNAD-MDH3/4/5 involved in malic acid metabolism may be the main reason for the higher malic acid accumulation in peach fruit from high-altitude peach-producing areas. Overall, this study elucidates the mechanism by which environmental factors enhance the accumulation of organic acids in peach fruit from high-altitude peach-producing areas from a multi-omics perspective, as well as providing a theoretical basis for screening key genes involved in organic acid metabolism in peach fruit.

Non-destructive assessment of apple internal quality using rotational hyperspectral imaging

This work aims to predict the starch, vitamin C, soluble solids, and titratable acid contents of apple fruits using hyperspectral imaging combined with machine learning approaches. First, a hyperspectral camera by rotating samples was used to obtain hyperspectral images of the apple fruit surface in the spectral range of 380~1018 nm, and its region of interest (ROI) was extracted; then, the optimal preprocessing method was preferred through experimental comparisons; on this basis, genetic algorithms (GA), successive projection algorithms (SPA), and competitive adaptive reweighting adoption algorithms (CARS) were used to extract feature variables; subsequently, multiple machine learning models (support vector regression SVR, principal component regression PCR, partial least squares regression PLSR, and multiple linear regression MLR) were used to model the inversion between hyperspectral images and internal nutrient quality physicochemical indexes of fruits, respectively. Through the comparative analysis of all the model prediction results, it was found that among them, for starch, vitamin C, soluble solids, and titratable acid content, 2nd Der-CARS-MLR were the optimal prediction models with superior performance (the prediction coefficients of determination Rp2 exceeded 90% in all of them). In addition, potential relationships among four nutritional qualities were explored based on t-values and p-values, and a significant conclusion was drew that starch and vitamin C was highly correlated.

Genetic and QTL analysis of sugars and acids content in sweet cherry (Prunus avium L.)

Abstract Sweet cherry is very appreciated by consumers because of its attractive appearance and taste, which is determined by the balanced sweet-sour flavor. In this work, the genetics of soluble solid content (SSC), titratable acidity (TA), sugars and organic acids was investigated in sweet cherry to facilitate breeding improvement for fruit quality. The fruits of five sweet cherry populations (N = 372), three F1 and two F2, were sampled over two years to evaluate SSC, TA, and the content of individual sugars (glucose, fructose, sorbitol, and sucrose) and organic acids (malic, quinic, oxalic, citric and shikimic) by ultra-performance liquid chromatography (UPLC). Glucose, followed by fructose, was the most abundant sugar, while malic acid was the predominant acid. Sorbitol and malic acid were the most stable compounds between years, and had the highest heritability, being also the best correlated to SSC and TA respectively, revealing their relevance for breeding. Significantly positive correlations were observed among sugars and SSC, and acids and TA, but high interannual variability between years was observed for all traits. QTL mapping for SSC, sugars, TA, and organic acids was performed using a multi-family approach with FlexQTL™. Twenty QTLs were detected consistently during the two phenotyped years, and several relevant regions with overlapping QTLs for sugars and acids were also identified. The results confirmed major stable SSC and TA QTLs on the linkage groups 4 and 6, respectively. Within the main LG4 SSC QTL region, where maturity and fruit development time QTLs have been previously detected, three stable sugar (glucose, sorbitol, and sucrose) and two acid (quinic, shikimic) QTLs were also identified, suggesting a pleiotropic effect of ripening date on the content of these compounds. The major malic acid QTL overlapped with TA QTL on LG6, thus TA QTL mapping in LG6 may correspond to malic acid QTLs. Haplotype analyses of major SSC and sugars QTL in LG4, and TA and malic acid in LG6 revealed haplotypes of breeding interest. Several candidate genes previously identified in other Prunus fruit species, like peach, were found to collocate with the QTLs detected herein. This work reports QTLs regions and haplotypes of sugar and acid content in a Prunus non-climacteric stone fruit for the first time.

Enhancement of Tomato Fruit Quality Through Moderate Water Deficit

In arid areas, water shortage has become a major bottleneck limiting the sustainable development of agriculture, necessitating improved water use efficiency and the full development of innovative water-saving irrigation management technologies to improve quality. In the present study, tomato (Solanum lycopersicum cv. Micro Tom) fruits were used as materials, and different irrigation frequencies were set during the fruit expansion stage. The normal treatment (CK) was irrigated every three days, while the water deficit treatments were irrigated at varying frequencies: once every 4 days (T1), 5 days (T2), 6 days (T3), 7 days (T4), and 8 days (T5). These corresponded to 80%, 70%, 60%, 50%, and 40% of the maximum field moisture capacity (FMC), respectively, with CK maintaining full irrigation at 90% of the maximum FMC. The water deficit treatment T3, with less stress damage to plants and the most significant effect on fruit quality improvement, was selected based on plant growth indices, photosynthetic characteristics, chlorophyll fluorescence parameters, and fruit quality indices, and its effects on carotenoids, glycolic acid fractions, and volatile compounds during tomato fruit ripening were further investigated. The outcome indicated that moderate water deficit significantly increased the carotenoid components of the tomato fruits, and their lycopene, lutein, α-carotene, and β-carotene contents increased by 11.85%, 12.28%, 20.87%, and 63.89%, respectively, compared with the control fruits at the ripening stage. The contents of glucose and fructose increased with the development and ripening of the tomato fruits, and reached their maximum at the ripening stage. Compared to the control treatment, the moderate water deficit treatment significantly increased the glucose and fructose levels during ripening by 86.70% and 19.83%, respectively. Compared to the control conditions, water deficit conditions reduced the sucrose content in the tomato fruits by 27.14%, 18.03%, and 18.42% at the mature green, turning, and ripening stages, respectively. The moderate water deficit treatment significantly increased the contents of tartaric acid, malic acid, shikimic acid, alpha ketoglutaric acid, succinic acid, and ascorbic acid, and decreased the contents of oxalic acid and citric acid compared to the control. The contents of total soluble sugar and total organic acid and the sugar–acid ratio were significantly increased by 48.69%, 3.71%, and 43.09%, respectively, compared with the control at the ripening stage. The moderate water deficit treatment increased the fruit response values to each sensor of the electronic nose, especially W5S, which was increased by 28.40% compared to the control at the ripening stage. In conclusion, during the ripening process of tomato fruit, its nutritional quality and flavor quality contents can be significantly improved under moderate (MD) deficit irrigation treatment. The results of this experiment can lay the foundation for the research on the mechanism of water deficit aiming to promote the quality of tomato fruit, and, at the same time, provide a theoretical basis and reference for tomato water conservation and high-quality cultivation.

Multi-omics analysis provides insights into the mechanism underlying fruit color formation in Capsicum

Fruit color is a crucial attribute of fruit quality in peppers (Capsicum spp.). However, few studies have focused on the mechanism of color formation in immature pepper fruits. In this study, the light-yellow color observed in immature CSJ009 fruits compared to CSJ010 could be attributed to decreased chlorophyll and carotenoid pigments. Through integrated analysis of the transcriptome and metabolome of CSJ009 and CSJ010, we identified 23,930 differentially expressed genes (DEGs) and 345 differentially accumulated metabolites (DAMs). Furthermore, integrated analysis revealed a strong correlation between the HCT-like gene and metabolite MWS0178 (chlorogenic acid). Paraffin section assay revealed that the epidermal cells of immature CSJ010 fruits exhibited a more compact arrangement with significantly greater length than those of CSJ009. Quantitative determination of carotenoids showed that lutein emerged as the predominant carotenoid in immature pepper fruits. Additionally, missense mutation of LCYB2 is likely to lead to a decrease in β-carotene content in immature CSJ009 fruits, whereas CCS may directly catalyze the conversion of lycopene to β-carotene in mature fruits. The null mutation in CCS promoted the biosynthesis of β,ϵ-branch carotenoids leading to lutein being the most abundant carotenoid found in orange CSJ010 fruits. These findings provide important insights into the mechanism underlying color formation in pepper fruits and establish a foundation for the further exploration of color-related genes.

Antioxidant Properties of Freeze Dried Mix Fruits and Vegetables Product ‘Miss Freezy’ Using Lyophilization Method

Background: The proper processing of fruits and vegetable-based food products will improve appearance, taste, bioactivities, and preservation. Freeze-dried (FD) or lyophilization of foods extends shelf life and preserves food's nutritional value and bioactivities. The objective of this study is to compare the antioxidant properties, nutritional value, and vitamins of fresh fruit-vegetables and the combined FD product. Methods: A combination of fruits (mango, papaya, star-fruit, guava, banana, bengkuang), and vegetables (cucumber), called “Miss Freezy” were cleaned with an ozonizer and processed using the lyophilization method. The antioxidant activities measured included 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), and Hydrogen Peroxide (H2O2) assay. While the proximate analysis measured was the determination of water content, ash content, fat content, protein and carbohydrate content, and vitamin C. Results: The value of antioxidant activity in fruit-vegetable combination FD products was higher than in fresh fruit. The median inhibition concentration (IC50) of DPPH, ABTS, and H2O2 scavenging activities were guava 48.74 µg/ml, guava 128.39 µg/ml, and banana 155.55 µg/ml, respectively. The results showed that the water content of fresh fruits, and vegetables was greater than FD products and inversely proportional to the level of ash, fat, protein, carbohydrates, and vitamin C lower than FD products. Conclusions: Based on the results of antioxidant activities, proximate analysis and vitamin C of the FD product was higher than fresh fruits and vegetables. The FD fruit-vegetable combination product can be used as an alternative snack product that is practical and healthy.

Comparative Evaluation of Calcium Sources and their Mode of Use on Apple Production in Acidic Soil under High Density Plantation System

Apples grown in Kashmir province are extremely prone to deterioration, particularly in post-harvest storage. Calcium is amongst the vital mineral element deceiving apple fruit quality, predominantly in acid soils deficit in available calcium. Calcium in sufficient quantity helps to retain apple fruit firmness and reduces the occurrence of physiological disorders, it also plays essential role to improve yield and quality of produce. Modes of calcium application and its different doses on two apple varieties was tested to improve yield and quality at Ambri Apple Research Centre, Sher-e-Kashmir University of Agricultural Sciences and Technology, Kashmir, India. The direct application of calcium to apple as spray is most effective method for escalating fruit calcium content and quality. Among sources and their mode of application calcium nitrate foliar application performed better than foliar application of calcium chloride in improving fruit quality and yield of Golden Delicious than Red Chief Camspur, whereas soil application of calcium nitrate showed least response to improve fruit quality and yield in both varieties under acidic soil atmosphere. Physiological loss in weight at 30 days and 60 days after harvesting was lower in foliar applied calcium than soil calcium application. The significant variation in total sugar content and TSS of apple fruits were observed in different calcium sources and their mode of application. Calcium nitrate foliar spray performed better than calcium chloride foliar spray in improving fruit quality. Our study did not find any adversity of dosage in plants whether applied to soil or directly to plant and we did observe better yields and quality at higher calcium doses. Among varieties Golden Delicious performed better than Red Chief Camspur. Results of research evidenced that preharvest calcium sprays increase yield, improved fruit quality and reduced its deterioration in post-harvest storage.

Preharvest salicylic acid and chitosan treatments reduce red drupelet reversion and enhance antioxidant capacity in blackberry fruit

Red drupelet reversion (RDR) is a postharvest physiological disorder affecting fresh blackberries during commercialization. The drupelets revert from fully black to red, causing detriments of the commercial value. The specific mechanism is still being investigated, some reports suggest that the occurrence of RDR is associated with pigment degradation in the fruit, and can be caused or aggravated by mechanical damage and storage conditions. Even, though studies report no significant alteration in blackberry organoleptic properties caused by RDR, the visual aspect of it affects the consumer perception of the fruit quality reducing marketability and ultimately generating economic losses. In this regard, preharvest treatments have been recently reported to have positive effects in reducing RDR in blackberries. In this study, we investigated the effects of chitosan (COS) and salicylic acid (SA) as preharvest treatments on the phenolic compound content and antioxidant capacity of blackberry fruit. The results showed that SA 3 mM and COS 0.25% treatments increased the total phenolic and flavonoid content while also enhancing the antioxidant capacity of blackberries. We also observed that the content of specialized metabolites and the activity of antioxidant enzymes have a negative correlation with the occurrence of RDR in blackberries.

Potential reformulation of food products two years after implementation of Nutri-Score in Belgium

Abstract Background Nutri-score is a front of pack labeling system that provides consumers with simplified information of the nutritional quality of food products. It is based on a five color (green to red) or letter (A to E) scheme that grades the quality of the product using an algorithm that takes into account the energy, sugar, saturated fats, salt, fiber, protein content, and percent of fruits and vegetables. In Belgium, Nutri-score was implemented on a voluntary basis in April 2019. This study aims to explore reformulation of products with Nutri-score by comparing their nutrient content and Nutri-score distribution in 2019 and 2021. Methods Product data from one of the major retailers was used in the analysis. Similar products in 2019 and 2021 with matched barcodes were used. Descriptive statistics were computed and statistical analyses such as the signed rank test and the McNemars test were performed to respectively evaluate the changes in the nutrient content and Nutri-score. The tests were conducted at 5% level of significance. Results From the matched sample of 668 products, about 55% had a Nutri-score of A and B in both 2019 and 2021. The proportion of food products with Nutri-Score of A/B and of D/E was not significantly different after two years of Nutri-Score implementation. Results showed a significant decrease in the median energy content of dairy, sauces, and meat products and in the median sugar content of dairy and fruit and vegetable products. There was a significant increase in the median fiber content of the dairy, meat products, and non-alcoholic beverages. For all food groups, the salt content of the products in 2019 and 2021 was not significantly different. Conclusions This two-year interval analysis described the changes in the classification and reformulation of the products with Nutri-score. Favorable changes in the nutrient quality of the product profiles reveals improvement in their reformulation. Key messages • In this analysis, changes has been observed in the nutrient content of food products between 2019 and 2021. • Producers or manufacturers should continue working on commitments to enhance the nutritional quality of the products delivered to consumers.

Identification and Functional Analysis of Key Genes Regulating Organic Acid Metabolism in Jujube Fruit

Organic acids are crucial indicators of fruit flavor quality, but the metabolic characteristics and regulatory genes of organic acids during jujube fruit development remain largely unexplored. In this study, the cultivar ‘Heigeda’ with a high organic acid content was used as the experimental material. The organic acid content was quantified, and key candidate genes were identified through transcriptome analysis. The results indicated that malic acid and citric acid were the main organic acid content in jujube fruit and increased gradually with fruit development. Transcriptome analysis identified nine genes associated with malic acid and seven with citric acid, with four genes co-regulating malic acid and citric acid. Functional assays by transient overexpression and silencing of these four genes in the jujube fruits revealed that overexpression significantly upregulated the malic and citric acid content. However, only the silencing of aconitase1 (ZjACO1) and aconitase3 (ZjACO3) significantly downregulated the content of malic and citric acids. Therefore, aconitase1 (ZjACO1) and aconitase3 (ZjACO3) are considered the key genes that regulate the metabolism of citric acid and malic acid in jujube fruits. Our study can enrich the regulation mechanism of the organic acid metabolism of jujube fruit and provide theoretical support for the efficient cultivation of jujube fruit.

TLC with densitometric and image analysis in the control of anthocyanin content in fruits of Rubus occidentalis and Rubus idaeus cultivars and hybrids

A TLC method was developed for the determination of anthocyanins in the fruits of some cultivated varieties of Rubus occidentalis (black raspberries) and Rubus idaeus (red raspberries) and their hybrids. Anthocyanin sets in fruits’ extracts were determined on TLC silica gel 60 F254 plates using mobile phase consisted of ethyl acetate-water-formic-acid (100:30:30, V/V), at 4°C (±1°C), at a distance of 70 mm with the use of densitometry and videoscanning. The obtained results were comparable to the results of quantitative analysis performed using by the HPLC-UV/VIS method performed on a Kinetex C-18 column using gradient elution comprising an increase concentration of acetonitrile-water-trifluoroacetic acid (50:50:0.1, V/V) in water-trifluoroacetic acid (99.9:0.1, V/V) from 12 % to 40 % within 40 minutes at 520 nm. The TLC method with videoscanning provides immediate capture of data for unstable compounds like anthocyanins before their partial degradation.

Screening Tomato Genotypes for B–Recovery and Acquisition Potential in Calcareous Soils

ABSTRACT Screening a suitable genotype is important for nutrient recovery and its acquisition potential. Twenty genotypes of tomato were studied under different doses of B-application. The indices of B use efficiencies, viz. apparent B recovery (ABR), fruit production efficiency (FPE), physiological efficiency (PE), agro-physiological efficiency (APE) and utilization efficiency ratio (UER) were worked out for tomato genotypes. The field experiment was laid out in a split-plot design for the two consecutive years, assigning three B levels (control i.e. without B application, @ 2.0 kg B ha−1 through borax and 0.25% boric acid foliar spray twice) in main plot and location-specific twenty tomato genotypes in subplots, replicated thrice. Soil applied B produced greater fruit yield than the twice foliar spray of 0.25% boric acid B. However, the tomato fruit yield was improved by 2–12% over control by soil applied B @ 2.0 kg B ha−1 through borax and twice foliar spray of B. Irrespective of genotypes, B content in fruit and shoot of tomato plant improved upon application of B. The apparent B recovery (ABR) and agronomic efficiency (AE) of B suggested that foliar application was more effective in comparison to soil application. The use efficiencies were highest in the cultivars NS–812 followed by NS–512 and B–9–2 in B-deficient calcareous soils with the application of 0.25% boric acid foliar spray twice. These genotypes could be a promising lines for breeding program for B enrichment in tomato for cultivation in B-deficient soils.

Effect of lemongrass and chili pepper oils on the quality of ripe tomato fruits stored under tropical ambient temperature

Postharvest quality of tomato (Solanum lycopersicum L.) fruits treated with lemongrass (Cymbopogon citratus L.) and chili pepper (Capsicum annuum L.) oil was evaluated. Tomato variety Roma fruits of uniform size and weight at the red stage of ripening were overlaid with lemongrass oil only (L1P0), chili pepper oil only (L0P1), or mixtures in a ratio 1:1 (L1P1), and 1:2 (L1P2 and L2P1). Control (L0P0) was not treated with any oil. Treated and untreated fruits were stored at 280±20C and 46%±2 RH for 12 days. Treatments L1P0 and L2P1 oil inhibited postharvest tomato fruit rot for 12 days, whereas L1P2, L0P1, and L1P1 oil and the control showed rot within the range of 86.6% - 100% in 12 days. L1P0 and L2P1 also slowed fruit softening and significantly reduced weight loss, though L1P0 was the most protective. Total soluble solid content of fruit was not affected by both L1P0 and L2P1 throughout storage, but the parameter reduced significantly (p<0.05) in fruits treated with L1P1, L1P2, L0P1 and in control. Reduction in titratable acidity during storage was least in fruits treated with L1P0 followed by L2P1, compared to that in other treatments and the control. This study showed that lemongrass oil applied as surface coating preserved tomato fruit quality in tropical ambient storage conditions for 12 days.

Effect of Rhizobacteria Application on Nutrient Content, Bioactive Compounds, Antioxidant Activity, Color Properties and Fruit Characteristics of Strawberry Cultivars

The aim of this study was to determine the effects of single and combined applications of plant-growth-promoting rhizobacteria (PGPR) bacteria on plant nutrition, biochemical content and fruit characteristics in Albion and Monterey strawberry cultivars. Bacillus subtilis OSU-142, Bacillus megaterium M3 and Paenibacillus polymyx were the PGPR used in the experiment. For each bacterial treatment, 10 mL of a 108 CFU mL−1 suspension was applied to the soil where Albion and Monterey cultivars were grown. PGPR bacteria were applied as single treatments and a mixture of equal amounts of these three bacterial species was applied as a mixed treatment. This study was carried out with a total of four different bacterial treatments and one control group. The highest fruit weight was obtained in the Monterey cultivar with 12.67 g in the Mix treatment and in the Albion cultivar with 11.79 g in the Bacillus megaterium M3 treatment. Regarding biochemical properties, Paenibacillus polymyxa was effective in influencing nutrient element content in fruits, while Bacillus subtilis OSU-142, Paenibacillus polymyxa and Bacillus megaterium M3 applications were more effective in leaf nutrient element content. It has been observed that the Mix treatment resulting from the combined use of bacteria, rather than their separate use, has a greater impact on fruit weight. Consequently, it has been understood that PGPR bacteria are potentially effective in improving the agronomic, pomological, and biochemical characteristics of strawberry cultivars and can be used in studies and breeding programs aimed at increasing strawberry yield and quality.

Nutrient content and ultra-performance liquid chromatography tandem mass spectrometry metabolomic comparative analysis of Lithocarpus corneus and Lithocarpus pachylepis.

China possesses abundant species resources in genus Lithocarpus Blume, commonly known as "acorns." These nuts are traditional foods in China, holding significant potential for local specialty food and rural economic development. To explore their edible value, we compared the nutritional components and metabolites between the fruits of Lithocarpus corneus (YD) and Lithocarpus pachylepis (HL), which are cultivated widely in south of China. Non-targeted metabolomics analysis of YD and HL was performed using ultra-performance liquid chromatography tandem mass spectrometry technology. A total of eight classes of differential metabolites (DAMs) were detected: alkaloids, amino acids and peptides, carbohydrates, fatty acids, polyketides, shikimates and phenylpropanoids, terpenoids, and other metabolites. In the positive ion mode, 225 DAMs were identified, whereas in the negative ion mode, 116 DAMs were identified. KEGG pathway enrichment analysis showed that the differentially abundant metabolites were generally enriched in three pathways: aminoacyl-tRNA biosynthesis, alanine, aspartate, and glutamate metabolism, and ABC transporters. The nutritional content of YD has higher moisture, fructose, and total flavonoid levels, but lower starch, protein, fat, glucose, sucrose, and total sugar content than HL. Additionally, YD contains more Ca, K, P, and Fe, but less Mg and Zn compared to HL. Analyses indicate that YD is nutrient-rich and beneficial, making it suitable for further development. Two species of Lithocarpus contain nandrolone, suggesting a new direction for specialty food development. The unique chemical composition and rich nutritional content of Lithocarpus fruits provide a theoretical basis for their development and application as food resources. PRACTICAL APPLICATION: L. corneus and L. pachylepis are traditional Chinese nuts, rich in starch, minerals, and flavonoids, making them suitable for consumption or use as food constituents. Their fruits contain various unique natural chemical compounds, indicating high application value and development potential.

Functional and Physiological Characterization of Tyrosine Decarboxylases from Olea europaea L. Involved in the Synthesis of the Main Phenolics in Olive Fruit and Virgin Olive Oil.

The phenolic composition of virgin olive oil (VOO) primarily depends on the phenolic content of the olive fruit. The purpose of this work was to characterize the first metabolic step in the synthesis of tyrosol (Ty) and hydroxytyrosol (HTy), whose derivatives are by far the predominant phenolics in both olive fruit and VOO. To this end, two genes encoding tyrosine/DOPA decarboxylase enzymes, OeTDC1 and OeTDC2, have been identified and functionally and physiologically characterized. Both olive TDC proteins exclusively accept aromatic amino acids with phenolic side chains, such as tyrosine and 3,4-dihydroxyphenylalanine (DOPA), as substrates to produce tyramine and dopamine, respectively. These proteins exhibited a higher affinity for DOPA than for tyrosine, and the catalytic efficiency of both proteins was greater when DOPA was used as a substrate. Both olive TDC genes showed a fairly similar expression profile during olive fruit ontogeny, with OeTDC1 consistently expressed at higher levels than OeTDC2. Expression was particularly intense during the first few weeks after fruit set, coinciding with the active accumulation of Ty and HTy derivatives. The data suggest that both olive TDCs are responsible for the initial step in the synthesis of the most important phenolics, both quantitatively and functionally, in VOO.

Hydroxycinnamic Acid Oligomers-Based Biostimulant Nurspray® Enhances Tomato Yield, Fruit Quality, and Reduces Blossom-End Rot

Tomato production faces challenges such as high input costs, pests, diseases, and climate change. Biostimulants like Nurspray®, based on hydroxycinnamic acid oligomers, offer a promising solution. This study evaluated the impact of different application timings of Nurspray® on tomato yield and fruit quality under open-field conditions. Four treatments were tested: T1 (control), T2 (Nurspray® at BBCH 19–51), T3 (Nurspray® at BBCH 19–51–61), and T4 (Nurspray® at BBCH 19–23–51). The results showed significant improvements in root development, canopy cover, and flowering for T3 and T4, with root systems increasing by up to 103% in T4 compared to the control. Fruit yield and quality were enhanced, with a reduction in blossom-end rot (BER) incidence to 0% in T3 and T4, compared to 5% in the control. Additionally, T4 produced the highest dry matter content in fruits. The optimal application strategy was three doses of Nurspray® at BBCH 19–23–51, enhancing both yield and fruit quality. This study highlights the potential of Nurspray® as an organic biostimulant in sustainable tomato farming.

Nondestructively Determining Soluble Solids Content of Blueberries Using Reflection Hyperspectral Imaging Technique

Effectively detecting the quality of blueberries is crucial for ensuring that high-quality products are supplied to the fresh market. This study developed a nondestructive method for determining the soluble solids content (SSC) of blueberry fruit by using a near-infrared hyperspectral imaging technique. The reflection hyperspectral images in the 900–1700 nm waveband range were collected from 480 fresh blueberry samples. An image analysis pipeline was developed to extract the spectrums of blueberries from the hyperspectral images. A regression model for quantifying SSC values was successfully established based on the full range of wavebands, achieving the highest RP2 of 0.8655 and the lowest RMSEP value of 0.4431 °Brix. Furthermore, three variable selection methods, namely the Successive Projections Algorithm (SPA), interval PLS (iPLS), and Genetic Algorithm (GA), were utilized to identify the feature wavebands for modeling. The models calibrated from feature wavebands generated an RMSEP of 0.4643 °Brix, 0.4791 °Brix, and 0.4764 °Brix, as well as the RP2 of 0.8507, 0.8397, and 0.8420 for SPA, iPLS, and GA, respectively. Furthermore, a pseudo-color distribution diagram of the SSC values within blueberries was successfully generated based on established models. This study demonstrated a novel approach for blueberry quality detection and inspection by jointly using hyperspectral imaging and machine learning methodologies. It can serve as a valuable reference for the development of grading equipment systems and portable testing devices for fruit quality assurance.

Bio-fortification with selenium (Se) improves quality and nutrient profile in citrus fruit

Selenium (Se) is an essential nutrient for the human body. Humans can enhance Se absorption by consuming horticultural plants, particularly fruits. Therefore, there is need for Se biofortification in fruits to meet the human demand for Se. The objective of this study was to determine the optimal Se application rate, application stage and method, and to assess their impacts on improving both the quality and nutrient profile of a sweet orange cultivar 'Hongjiangcheng' (Citrus sinensis (L.) Osbeck). 'Hongjiangcheng’ is a notable variety of mandarin orange, acclaimed for its large size, thin and smooth skin, orange-red flesh, tender and juicy texture, balanced sweetness and acidityand distinctive flavor. A field experiment was conducted at the Qiaotou Town Test Base in Chengmai County, Hainan Province, China. Biofortification of Se was done through foliar and soil application methods. Treatments were: Control (C) with no application of Se, foliar application of 25 (SeF1), 50 (SeF2), 100 (SeF3) and 200 (SeF4) mg/L and soil application of 100 mg/L (SeS1) as well as a combination of 100 mg/L Se in soil along with 50 mg/L Se on leaves (SeS1F2). At start of the experiment, 189 healthy, four-year-old citrus trees of similar size and normal growth were selected. The trees were divided into three groups of 63 each. Each group received the aforementioned treatments at the young fruit, expanding fruit and premature fruit stages. The Se was applied once during each stage before 9:00 am on sunny days. Treatments were arranged in a randomized complete block design with 9 biological replicates (7 treatments × 9 replicates = 63 citrus trees/ application stage). Foliar application of Se at rate of 200 mg/L (SeF4) enhanced total Se content in leaves by 105, 34 and 69 % at young fruit, expanding fruit and premature fruit stages compared to control (p≤0.05). Respective increments in fruits were 264, 22 and 21 %. The total Se content in leaves were 32 and 40 % higher in the SeF4 (foliar) compared to SeS1 and SeS1F2 (soil) treatments across all development stages (p≤0.05), respectively. The respective increments in fruits total Se content were 16 and 52 %. Only at the young fruit stage, the organic Se content in fruits was significantly higher in the SeF4 compared to soil application treatments (p≤0.05). Single fruit weight was enhanced by 16.61, 13.69 and 4.36 g by foliar than soil application at young fruit, expanding fruit and premature fruit stages, respectively. It was significantly higher (155.53 vs. 113.13 g) after application of SeF4 treatment at young fruit stage relative to all other treatments (p≤0.05). The application of SeF4 at the young fruit stage resulted in an increased seed rate (97 %), total soluble solids (28 %) and solid-to-acid ratio (75 %), while titratable acid decreased by 26 % compared to the control. Interestingly, Se application had non-significant effects on the fruit shape index, peel rate and residue rate across all stages (p>0.05). Additionally, a positive correlation was observed between fruit Se content and several quality indices like total soluble solids, solid acid ratio, fruit shape index and fruit weight at young fruit stage (p≤0.05). It is concluded that foliar application of Se at 200 mg/L (SeF4) during young fruit stage improved citrus Se content, its fruit weight and quality indices establishing these fruits as a valuable source of Se-rich food for human consumption.