Organic Acids In Fruits Research Articles

Comparative evaluation of the biochemical composition of fruits Malus spp.

To determine and compare the content of biochemical compounds in fruits of nine cultivars of M. domestica Borkh. and ten of Malus spp. (given in the research materials), to select the most promising for use in further breeding and recommend for use in various directions, considering the biochemical complex of characters, taste, and marketable qualities of fruits. The dry matter content, a sum of sugars, titratable acids, tannins, and ascorbic acid was evaluated for two years according to generally accepted operating methods. The large-fruited apple cultivars were found to have values of dry matter (11.2-22.8%) and small-fruited (15.5-30.9%); the total amount of sugars in large-fruited cultivars varies from 6.7 to 10.9%, in small-fruited from 7.5 to 12.7%; the amount of ascorbic acid in fruits of M. domestica fruits averaged from 6.0 to 12.2 mg.100 g-1, in crabapple from 6.6 to 22.8 mg.100 g-1; titratable organic acids in fruits of large cultivars ranged from 0.74 to 1.67%, in small ones from 1.50 to 2.34%; tannins content was found in the range from 0.06 to 0.52% in high-fruited cultivars and from 0.29 to 2.61% in lower-fruited ones. Comparative evaluation of the biochemical composition of fruits between large-fruited and small-fruited species and cultivars of apple trees showed that representatives of Malus spp. are more promising for use in breeding and industrial purposes. The dynamics of the decrease of dry soluble substance's weight and the increase of ascorbic acid content in apple tree fruits were also noted.

Effect of water deficit stress during fruit cultivation on the carbon stable isotopes of organic acids in Japanese apricots and liqueur prepared from these fruits

ABSTRACT The objective of this study was to assess the impact of water deficit stress during fruit cultivation on the δ 13C values of citric acid and malic acid in Japanese apricots at different ripeness stages and their resulting liqueurs. Our experiments show that water deficit stress increases the δ 13C values of citric acid and malic acid in tree-ripened fruits, counteracting the typical decrease during ripening. However, water deficit treatment has a minimal effect on the δ 13C values of organic acids in green fruits. Regardless of fruit ripeness or water status, the δ 13C values of organic acids in fruits are directly reflected in the resulting liqueurs. Overall, water deficit stress during fruit cultivation has the potential to promote similarity in the δ 13C values of organic acids across fruits at different ripeness levels, reducing variations among liqueurs derived from fruits of varying ripeness levels.

Transcriptome and Metabolome Analyses Reveal Sugar and Acid Accumulation during Apricot Fruit Development

The apricot (Prunus armeniaca L.) is a fruit that belongs to the Rosaceae family; it has a unique flavor and is of important economic and nutritional value. The composition and content of soluble sugars and organic acids in fruit are key factors in determining the flavor quality. However, the molecular mechanism of sugar and acid accumulation in apricots remains unclear. We measured sucrose, fructose, glucose, sorbitol, starch, malate, citric acid, titratable acid, and pH, and investigated the transcriptome profiles of three apricots (the high-sugar cultivar ‘Shushanggan’, common-sugar cultivar ‘Sungold’, and low-sugar cultivar ‘F43’) at three distinct developmental phases. The findings indicated that ‘Shushanggan’ accumulates a greater amount of sucrose, glucose, fructose, and sorbitol, and less citric acid and titratable acid, resulting in a better flavor; ‘Sungold’ mainly accumulates more sucrose and less citric acid and starch for the second flavor; and ‘F43’ mainly accumulates more titratable acid, citric acid, and starch for a lesser degree of sweetness. We investigated the DEGs associated with the starch and sucrose metabolism pathways, citrate cycle pathway, glycolysis pathway, and a handful of sugar transporter proteins, which were considered to be important regulators of sugar and acid accumulation. Additionally, an analysis of the co-expression network of weighted genes unveiled a robust correlation between the brown module and sucrose, glucose, and fructose, with VIP being identified as a hub gene that interacted with four sugar transporter proteins (SLC35B3, SLC32A, SLC2A8, and SLC2A13), as well as three structural genes for sugar and acid metabolism (MUR3, E3.2.1.67, and CSLD). Furthermore, we found some lncRNAs and miRNAs that regulate these genes. Our findings provide clues to the functional genes related to sugar metabolism, and lay the foundation for the selection and cultivation of high-sugar apricots in the future.

Biofertilizer and lighting as factors affecting tomato growth, development and biochemical composition

A comprehensive study of growth and biochemical composition of the Blagodatny variety tomato plants grown with the use of bacterial spores Bacillus cereus strain 96 under continuous LED lighting based on full spectrum photons in the proportion B: G: R: FR ~ 17: 23: 43: 17 was conducted. Plants grown with high-pressure sodium lamps (HPS) without bacterial culture action were used as controls. A number of parameters reflecting plant growth and quality of tomato fruits were studied - the content of photosynthetic pigments, dry matter and organic acids. It was shown that during the growing season, tomato plants grown under LED illumination had a longer shoot length compared to the plants in the sodium variant. The action of the bacteria manifested itself during fruit ripening with significant differences under both sodium and LED lighting. The effect of dry matter under the influence of bacteria on the plants grown with sodium lighting did not differ from the control variant. The observed differences became more pronounced and reliably significant in the plants under LED lighting. Application of B. cereus bacterial culture increased the concentration of chlorophylls a, b and carotenoids compared to the control. When evaluating the effect of different types of lighting and the use of B. cereus bacteria on the accumulation of organic acids in fruits, it was found that LED lighting had a better effect on the synthesis of organic acids. Tomato plants treated with B. cereus were distinguished by the formation of fruits with a high content of succinic, malic and citric acids with a sodium type of lighting. When analyzing the fruits of tomato plants grown under LED lighting, a change in the accumulation of only succinic acid was noted. The use of different lighting sources and biofertilizers caused changes in the development of tomato plants under climate chamber conditions.

Analysis of organic acid metabolism reveals citric acid and malic acid play major roles in determining acid quality during the development of kiwifruit (Actinidia eriantha).

Actinidia eriantha is one of the most important kiwifruit species in Actinidia. The relative high accumulation of organic acids in fruit of A. eriantha is an unfavorable factor for organoleptic quality. To identify key metabolic enzymes and genes involved in organic acids accumulation during fruit development, physiological, biochemical, and molecular experiments were conducted for the dynamic fruit samples of a new kiwifruit cultivar, A. eriantha 'Ganlv 1'. The contents of citric acid and malic acid increased greatly during fruit development, while quinic acid content decreased obviously. Significant positive correlations were observed between fruit titratable acidity and the contents of both citric acid and malic acid, and a significant negative correlation was found between fruit titratable acidity and the quinic acid content. The high accumulation of citric acid was found to be caused by the increased activity of citrate synthase (CS), and the decreased activities of two degradation-related enzymes, mitochondrial aconitase and nicotinamide adenine dinucleotide (NAD)-dependent isocitrate dehydrogenase. In addition, the accumulation of malic acid depended mainly on the increased synthesis catalyzed by NAD-dependent malate dehydrogenase (NAD-MDH) and phosphoenolpyruvate carboxylase. Further analysis suggested that AeCS2 and AeMDH2 played pivotal roles in controlling the activities of CS and NAD-MDH respectively. The high accumulation level of citric acid relied on both the strong synthesis ability and the weak degradation ability. The accumulation level of malic acid was mainly affected by the synthesis. The novel information would be helpful for our understanding of the formation of fruit acidity quality. © 2023 Society of Chemical Industry.

Simultaneously quantification of organic acids metabolites by HPLC mass spectrometry to reveal the postharvest quality change in cherry tomato

The organic acids in fruits have critical impacts on palatability and flavor. In this paper, we established a method to quantify 21 essential organic acids in animal and plant matrices using HPLC mass spectrometry with high sensitivity and broad applicability. The organic acids in 12 animal and plant matrices were quantified. Additionally, the profile and concentration of organic acids could achieve the classification of samples. The fruit quality traits and important organic acids content during the storage of cherry tomatoes were monitored via our method. Nine organic acids changed significantly in 16 days of storage, especially citric acid, as the most predominant organic acid, decreased from 4260 to 2290 μg/g, leading to a decline in sourness of 46.2 %. In contrast, after 16 days of storage, galacturonic, gluconic, malonic and quinic acids increased by 155 %, 88 %, 162 %, and 112 %, respectively, which had a potential effect on softening and deteriorating of cherry tomatoes.

Inheritance of Fruit Weight, Size and Organic Acid Content in a Distant Hybrid Population of Longan ‘Huanongzao’ and Lychee ‘Ziniangxi’

The type and content of organic acids in fruits are important factors that determine the traits, such as the nutrition and flavor of fruits. Fruit weight and size are also very important economic characters in fruit breeding research. To investigate the inheritance patterns in longan, fruit organic acid contents, weight, and size were measured in the distant hybridization progenies of longan ‘Huanongzao’ and lychee ‘Ziniangxi’. The results revealed that the malic acid accumulation exhibited mid-parent heterosis, citric acid content showed a tendency towards depression, and oxalic acid, ketoglutaric acid, fumaric acid, gallic acid, and total acid contents exhibited transgressive inheritance. The inheritance patterns in fruit weight, length and diameter tended towards smaller and degraded. The coefficient of variation (CV) for the organic acids ranged from 35.77–90.20%, and the heritability (H2) was 72.35–97.44%. High CV (55.44%) coupled with medium H2 (28.72%) were observed in fruit weight, however, low CV (12.29% and 12.50%) coupled with high H2 (68.95% and 69.25%) were shown in fruit length and diameter. In this study, the genetic variation of acid contents, fruit weight and size in the F1 population of longan and lychee were analyzed for the first time, providing an informative and theoretical basis for the selection and breeding of longan cultivars.

Established methods and comparison of 10 organic acids based on reversed phase chromatography and hydrophilic interaction chromatography

ABSTRACT High performance liquid chromatography (HPLC) methods have been established for simultaneously determining the 10 organic acids in fruit or soil. Two liquid chromatographic (LC) columns with reversed phase (RP) (Titank C18) and hydrophilic interaction (HILIC) (Poroshell 120 HILIC-Z) were selected to separate organic acids in molecular or ionic state, respectively. Meanwhile, the mobile phases had different solvents and pH values in the two states. Results indicated that these two columns can complement each other and avoid various matrix interferences. The limits of detection (LOD) of organic acids (S/N ≥ 3) were 0.002–0.521 μg∙mL−1 in the molecular state and 0.003–0.459 μg∙mL−1 in the ionic state, and the corresponding limits of quantification (LOQ) (S/N ≥ 10) were 0.007–1.737 μg∙mL−1 and 0.009–1.530 μg∙mL−1. The above methods can provide a technical support for the analysis of organic acid components in other matrices.

Changes and response mechanism of sugar and organic acids in fruits under water deficit stress.

The content and the ratio of soluble sugars and organic acids in fruits are significant indicators for fruit quality. They are affected by multiple environmental factors, in which water-deficient is the most concern. Previous studies found that the content of soluble sugars and organic acids in fruit displayed great differences under varied water stress. It is important to clarify the mechanism of such difference and to provide researchers with systematic knowledge about the response to drought stress and the mechanism of sugar and acid changes in fruits, so that they can better carry out the study of fruit quality under drought stress. Therefore, the researchers studied dozens of research articles about the content of soluble sugar and organic acid, the activity of related metabolic enzymes, and the expression of related metabolic genes in fruits under water stress, and the stress response of plants to water stress. We found that after plants perceived and transmitted the signal of water deficit, the expression of genes related to the metabolism of soluble sugars and organic acids changed. It was then affected the synthesis of metabolic enzymes and changed their metabolic rate, ultimately leading to changes in soluble sugar and organic acid content. Based on the literature review, we described the pathway diagrams of sugar metabolism, organic acid metabolism, mainly malic acid, tartaric acid, and citric acid metabolism, and of the response to drought stress. From many aspects including plants’ perception of water stress signal, signal conversion and transmission, induced gene expression, the changes in soluble sugar and the enzyme activities of organic acids, as well as the final sugar and acid content in fruits, this thesis summarized previous studies on the influence of water stress on soluble sugars and the metabolism of organic acids in fruits.

The summer sprays of iodine with calcium chloride are successful in biofortifying apples with iodine and improving their storability

ABSTRACT This study investigated the impacts of spraying iodine (I) as potassium iodide (KI) and K-iodate (KIO3) with/without calcium chloride (CaCl2) on apple (Malus domestica Borth.) enrichment with I as well as on fruit quality. ‘Idared’ apple trees were sprayed with I: (i) in the summer, five times at a rate of 0.1 kg ha−1 in each treatment with or without CaCl2 and (ii) preharvest (2 weeks before harvest) at a rate of 0.5 kg ha−1. Iodine concentrations in apples sprayed with this nutrient in the summer varied from 41 to 70 µg 100 g−1 FW. The preharvest I sprays increased apple I concentrations up to 63–69 µg 100 g−1 FW. Only the addition of CaCl2 to the spray solution containing KIO3 enhanced fruit I concentration. The sprays of I with CaCl2 increased apple Ca concentration as well as flesh firmness and contents of organic acids in fruit after storage. The percentage of I losses did not differ between combinations, averaging 11.3%. It is concluded that the summer sprays of KI or KIO3 with CaCl2 should be recommended to biofortify apples with I and improve their Ca-related storability.

Improving Bell Pepper Crop Performance and Fruit Quality under Suboptimal Calcium Conditions by Grafting onto Tolerant Rootstocks

Calcium deficiency or its inefficient translocation to pepper fruits leads to considerable economic loss by reducing the number of marketable fruits. The present study proposes grafting as an environmentally friendly technique to effectively reduce such loss. A commercial variety (Al-cudia F1; V) was grafted onto two pepper (Capsicum annum L.) accessions (V/A6 and V/A8), a hybrid rootstock (V/N) and was also self-grafted (V/V). All rootstock–scion combinations were cultivated under greenhouse conditions with optimal and suboptimal Ca supply and assessed for fruit yield and biomass production, gas exchange and chlorophyll fluorescence, mineral concentration in leaves and fruits as well as several fruit quality parameters. The V/N plants demonstrated an enhanced capacity for increased biomass, higher yield and number of commercial fruits and greater mean fruit weight compared with the other rootstock–scion combinations. These improvements are attributed primarily to increased intrinsic water efficiency. Additionally, a significantly higher Ca concentration in leaves was found under suboptimal Ca conditions in the V/N combination than that found in the other rootstock–scion combinations indicating a higher capacity for Ca uptake and translocation. Under the same conditions, the concentration of organic acids in fruits, such as citric and tartaric, which impact the organoleptic quality, was also higher in V/N plants. Consequently, we can conclude that grafting pepper onto tolerant rootstocks is a successful tool for ameliorating the negative impact of suboptimal Ca conditions on pepper crop performance and fruit quality.

Genome-Wide In Silico Analysis and Expression Profiling of Phosphoenolpyruvate Carboxylase Genes in Loquat, Apple, Peach, Strawberry and Pear

Phosphoenolpyruvate carboxylase (PEPC) genes have multiple potential roles in plant metabolism such as regulation and accumulation of organic acids in fruits, movement of guard cells and stress tolerance, etc. However, the systematic identification and characterization of PEPC genes in Rosaceae species i.e., loquat, apple, peach, strawberry, and pear are yet to be performed. In present study, 27 putative PEPC genes (loquat 4, apple 6, peach 3, strawberry 9, and pear 5) were identified. To further investigate the role of those PEPC genes, comprehensive bioinformatics and expression analysis were performed. In bioinformatic analysis, the physiochemical properties, conserved domains, gene structure, conserved motif, phylogenetic and syntenic analysis of PEPC genes were performed. The result revealed that the PEPcase superfamily domain was conserved in all examined PEPC proteins. Most of the PEPC proteins were predicted to be localized in cytonuclear. Genomic structural and motif analysis showed that the exon and motif number of each PEPC gene ranged dramatically, from 8 to 20, and 7 to 10, respectively. Syntenic analysis indicated that the segmental or whole-genome duplication played a vital role in extension of PEPC gene family in Rosacea species. The Ka and Ks values of duplicated genes depicted that PEPC genes have undergone a strong purifying selection. Furthermore, the expression analysis of PEPC genes in root, mature leaf, stem, full-bloom flower, and ripened fruit of loquat, apple, peach, strawberry, and pear was performed. Some genes were differentially expressed in aforementioned plant tissues, signifying their role in plant metabolism. This study provides the first genome-wide identification, characterization, and expression profiling of PEPC gene family in Rosaceae species, and provides the foundation for further functional analysis.

Effect of biostimulants on the growth, yield and nutritional value of Capsicum annuum grown in an unheated plastic tunnel

Recent years have witnessed an increased interest in the cultivation and consumption of peppers. Therefore, new solutions are being sought to provide pepper plants with the most favorable conditions for growth and development. In view of the above, the aim of this study was to evaluate the effect of selected biostimulants on the biometric parameters, yield and nutritional value of Capsicum annuum fruit. The research hypothesis postulates that biostimulants can increase the yield and improve the nutritional quality of pepper fruit. The experiment was conducted in an unheated plastic tunnel. The experimental materials comprised three sweet (‘Solario F1’, ‘Turbine F1’ and ‘Whitney F1’) and two hot (‘Cyklon’ and ‘Palivec’) cultivars of C. annuum. It was found that the combined application of environmentally-friendly microbial-based biostimulants (BB Soil, BB Foliar, Multical, MK5 and Biocin F) did not clearly improve the morphological traits of pepper fruit, yield or the concentrations of sugars and organic acids in fruit, therefore their use is not economically justified. Hot peppers had a higher content of dry matter, total sugars and L-ascorbic acid than sweet peppers. The analyzed biostimulants increased nitrate (V) concentrations in the fruit of both hot and sweet peppers. ‘Turbine F1’ and ‘Solario F1’ were particularly prone to nitrate (V) accumulation in fruit, therefore the use of biostimulants should be limited in their cultivation. Pepper fruits with the largest horizontal diameter and the thickest skin should be preferred because these traits are associated with high sugar content.

Genome-Wide Identification, Characterization and Expression Profiling of Aluminum-Activated Malate Transporters in Eriobotrya japonica Lindl.

Aluminum-activated malate transporters (ALMTs) have multiple potential roles in plant metabolism such as regulation of organic acids in fruits, movement of guard cells and inducing tolerance against aluminum stress. However, the systematic characterization of ALMT genes in loquat is yet to be performed. In the current study, 24 putative ALMT genes were identified in the genome of Eriobotrya japonica Lindl. To further investigate the role of those ALMT genes, comprehensive bioinformatics and expression analysis were performed. In bioinformatics analysis, the physiochemical properties, conserved domains, gene structure, conserved motif, phylogenetic and syntenic analysis of EjALMT genes were conducted. The result revealed that the ALMT superfamily domain was conserved in all EjALMT proteins. EjALMT proteins were predicted to be localized in the plasma membrane. Genomic structural and motif analysis showed that the exon and motif number of each EjALMT gene ranged dramatically, from 5 to 7, and 6 to 10, respectively. Syntenic analysis indicated that the segmental or whole-genome duplication played a vital role in extension of the EjALMT gene family. The Ka and Ks values of duplicated genes depicted that EjALMT genes have undergone a strong purifying selection. Furthermore, the expression analysis of EjALMT genes was performed in the root, mature leaf, stem, full-bloom flower and ripened fruit of loquat. Some genes were expressed differentially in examined loquat tissues, signifying their differential role in plant growth and development. This study provides the first genome-wide identification, characterization, and relative expression of the ALMT gene family in loquat and provides the foundation for further functional analysis.

Antibacterial Approach Of Lactobacillus Species Isolated From Exterior Of Fruits

Probiotics are important to guarantee the food production of many people all over the world, particularly those who are oppressed and highly susceptible. Some of this will be enhanced by increasing the number of natural resources that can be used to make consumable food products and minimizing generally pro components to generate food that is safe to eat and rich in nutrients. Lactobacillus, a carboxylic acid bacterium, was isolated primarily from decaying vegetables, fruits, and room trash. Genus Lactobacillus belong cluster of carboxylic bacterium that is represented as a gaggle of heterogeneous, regular non-spore-forming, gram-positive rods that have numerous habitats like plants and duct tracts and throughout the surroundings. Lactobacilli strains, often known as probiotics, are beneficial bacteria that improve digestion, combat disease, and promote digestion in humans and animals. Some species like true bacteria Plantarum, true bacteria casei, and true bacteria bulgaricus are typically isolated from farm. A natural protection exists in a number of fruits. Organic acids in fruits are sufficient to generate a pH of four or lower on the pH scale. The most essential determinant in defining the dominant microflora in fruits is the pH scale, and consequently the type of acid. A pH scale cannot support the growth of food-borne bacteria that are harmful to human health. The carboxylic acid bacterium performs a critical role in protecting the host against hazardous pathogens while also strengthening the system. Carboxylic acid bacteria are great sources of probiotics with potential qualities that, when administered in sufficient levels, can benefit the host's health.

Gas chromatography-mass spectrometric determination of organic acids in fruit juices by multiwalled carbon nanotube-based ion-pair dispersive solid-phase extraction and in situ butylation.

Fruit juices are naturally acidic, and the acidity is due to the formation of various organic acids formed in several metabolic processes. The content of acids varies due to various processing parameters during the preparation of fruit juices and their packaging for commercialization. Quantitative determination of organic acids provides the necessary information leading to changes occurred during processing. The organic acids were extracted by ion-pair dispersive solid-phase extraction by multiwalled carbon nanotubes and analyzed using gas chromatography-mass spectrometry (GC-MS) and in situ butylation. The developed analytical method was validated, and the obtained results showed a linearity in the range of 0.5-5000 μg/L levels of the analytes with limit of detection and quantification values of 2-10 and 5-20 μg/L, respectively. The inter- and intra-day reproducibilities are less than 15% with 80%-98% recoveries and less than 20% matrix effect. The developed method was used for the quantitative determination of organic acids present in fresh and packaged apple, grape, orange, and pomegranate juice samples. The content of organic acids was observed in the range of 0.26-3793 μg/L. Pimelic acid was not detected in any of the analyzed fruit juices. Fumaric acid (FA) was observed to be a major organic diacid present in the natural fruit juices. The results indicated that the processing of fruit juices for packaging decreases the content of organic acids in fruits. The developed GC-MS-based analytical method for the analysis of organic acids has good sensitivity and reproducibility for the quantitative determination of various organic acids in fruit juices. FA was observed to be the major carboxylic acid present in fruits. The processed juice samples possess the lowest concentration of organic acids, suggesting that processing has a significant effect on the concentration of organic acids in fruits.

Biochemical content in fruits of peach and nectarine cultivars

In Turkey, there is an increasing interest for peach and nectarine fruits due to their sensory properties and nutritional values. The large diffusion of new peach and nectarine cultivars requires the knowledge of all fruit characteristics in connection with the cultivation area to satisfy market demand. This study seeks to determine fruit quality attributes and nutraceutical values of 7 commercially important peach (Glohaven, Dixired, Cresthaven, Redhaven, Merrill Gem Free, June Gold, and Jefferson) and 4 nectarine cultivars (Nectared4, Gransun, Cherokee, and Royal Glo) grown in Malatya region of Turkey. The fruits were evaluated for their phenolic compounds (protocatechuic, rutin, quercetin, gallic acid, catechin, chlorogenic acid, caffeic acid, syringic acid, p - coumaric acid, o - coumaric acid, phloridzin, and ferulic acid), organic acids (citric acid, tartaric acid, malic acid, succinic acid, and fumaric acid), vitamin C, and specific sugars (glucose, fructose, and sucrose). The results showed that peach and nectarine cultivars grown in the Malatya region exhibit an appreciable quality, but there are significant differences in quality properties of the fruits in different cultivars. Rutin (73.549 mg kg-1), caffeic acid (70.142 mg kg-1), catechin (146.609 mg kg-1), and chlorogenic acid (211.879 mg kg-1) were major phenolic compounds in peach and nectarine fruits. Citric acid and malic acid were dominant organic acids in fruits of peach and nectarine cultivars.

Physicochemical characteristics and rheological behaviour of some fruit juices and their concentrates

Fruit juices and their concentrates are popular drinks consumed by people of all ages for their sensory and nutritional qualities. In this paper, the physicochemical and rheological properties of african star apple, apple, apricot, banana, cherry, goldenberry, grape, guava, mango, medlar, orange, peach, pear, plum, pomegranate and pomelo juices, and their concentrates were reviewed. The selection of cultivars is a critical factor for the production of juices rich in healthy compounds and the quality of fruit juice strongly depends on processing technology. In summary, carbohydrates (fructose, glucose, sorbitol and sucrose), organic acids (ascorbic, citric, malic and shikimic acids), amino acids (asparagine, proline, glycine, serine, methionine and alanine) and phenolic compounds (catechin, chlorogenic acid and rutin) are among the significant constituents of fruit juices, and their concentrates. Also, the content of organic acids in fruit juices not only influence their taste and flavour but also their nutrition, stability, acceptability and keeping quality. Understanding of rheological properties of fruit juice is essential for quality control, process engineering application (designing and selection of proper equipment including heat exchangers, transport systems, evaporators and pumps), calculating energy usage and power requirement for mixing. The rheological behaviour of fruit juices and concentrates can be described by different rheological models depending on the nature of the juices. Several investigators used and suggested the Newtonian and Herschel-Bulkley models describe the rheological behaviour of various fruit juices. The apparent viscosity of fruit juice decreased considerably at higher temperatures. The effect of temperature on the apparent viscosity is generally expressed by the Arrhenius relationship and the activation energy (Ea) for fruit juices flow increased with the concentration of the juices. Higher activation energy means that the apparent viscosity is relatively more sensitive to temperature change.

Geographic Variability of Sugars and Organic Acids in Selected Wild Fruit Species.

The chemical variability of bilberry (Vaccinium myrtillus L.), wild strawberry (Fragaria vesca L.), cornelian cherry (Cornus mas L.) and rosehip (Rosa canina L.) based on the content of individual and total sugars and organic acids in fruit was investigated. The fruits were picked in fully ripened condition within the period from 2014 to 2015 from different locations. The fresh fruits were analyzed with the high performance liquid chromatography (HPLC) technique for the purpose of identifying and quantifying the content of glucose, fructose and sucrose, as well as malic, citric, fumaric and shikimic acids. However, the content of individual sugars and organic acids differed by locations as well as by growing year within the same wild fruit species. The differences between wild fruit species as well as among different locations are presented by principal component analysis (PCA). Based on results obtained, rosehip fruits with higher sugars and organic acids ratio (S/A) are suitable for production of “pekmez” and drying, while genotypes of cornelian cherry, wild strawberry and bilberry with lower S/A are recommended for production of juices and gelatin products. The research results show that specific environmental conditions may influence significantly the content of analyzed parameters, as is the case with cornelian cherry and rosehip. Considering that the food industry is searching for new products, the wild fruit species analyzed represent a promising source of ingredients for the development of beverages and foods with functional properties as well as for supplements and nutraceuticals.

Influence of irrigation on yield and primary and secondary metabolites in two chilies species, Capsicum annuum L. and Capsicum chinense Jacq

The effects of water stress on plant growth, yield, primary metabolites (sugars, organic acids, ascorbic acid) and secondary metabolites (total phenolic content, capsaicin and dihydrocapsaicin) accumulation, were evaluated for greenhouse production. A pot experiment was conducted on two species of chilies Capsicum annuum L. var 'Chili-AS Rot' and Capsicum chinense Jacq. var 'Naga Morich'. Plants were irrigated at two different treatments, optimal irrigation or field capacity and deficit irrigation or 50 % field capacity, which can be treated as drought stress. The effects of drought stress on quantity and quality of the yield, (primary and secondary metabolites) were studied. Deficit irrigation affected yield quantity, as both chili species had lower yield at deficit irrigation. Species C. chinense 'Naga Morich' under deficit irrigation abscised the flowers, thus no fruits were harvested at the third picking. Concentrations of sugars were lower at both plant species under deficit irrigation. Concentrations of organic acids in fruits of C. annuum 'Chili-AS Rot', such as citric acid, oxalic acid, fumaric acid, quinic acid were higher at optimal irrigation. Malic acid concentrations were similar at both irrigation treatments. In the fruits of C. chinense Jacq. 'Naga Morich' the concertation of citric acid and ascorbic acid was higher with optimal irrigation. Concentrations of other organic acids were higher at deficit irrigation. C. annuum 'Chili-AS Rot' had higher concentration of ascorbic acid and total phenolic content at optimal irrigation and higher capsaicin and dihydrocapsaicin concentrations in stressed plants. C. chinense 'Naga Morich' had higher concentrations of capsaicin, dihydrocapsaicin and total phenolic content at optimal irrigation regime.