Succinic Acid Concentration Research Articles

Optimization of succinic acid production from xylose mother liquor (XML) by Actinobacillus succinogenes using response surface methodology

In the present study, conditions for succinic acid (SA) production using xylose mother liquor (XML) as culture medium by Actinobacillus succinogenes GXAS137 were optimized. Firstly, single–factor experiments were performed to evaluate the basal culture medium for SA fermentation. Thereafter, the Plackett–Burman design was used to screen out three significant factors of XML, corn steep liquor powder (CSLP) and MgCO3 affecting the SA yields from the original nine factors. Subsequent use of steepest ascent experiment determined the center area of the three factors. Finally, the response surface methodology was used to further optimize the interactions between the three main factors and predict the maximum SA concentration through Box-Behnken design. The optimal conditions of SA fermentation were maximally documented in the XML (110 g/L), CSLP (18.86 g/L) and MgCO3 (69.12 g/L). The maximum production of SA was 58.06 ± 0.57 g/L after 60 h with a yield of 0.72 ± 0.06 g/g total sugar, approaching the predicted value (57.99 g/L). It was 1.63-fold of the SA production obtained with the basic medium (35.54 g/L). In addition, batch fermentations were carried out in a 1.3-L stirred bioreactor and SA reached 58.47 g/L. These results indicate that XML could be an alternative substrate for the economical production of SA by A. succinogenes GXAS137.

Optimizing the fermentation conditions of fermented goji using sensory analysis and the biomass of Lactiplantibacillus plantarum NCU137

The main objective of this study was to optimize the fermentation conditions of goji and to analyze the sugar, organic acid, amino acid, and flavor compounds before and after the fermentation of goji. Based on the single-factor experiment, orthogonal array design and the range analysis, the optimized conditions for fermented goji were 30% raw material concentration, 28 h fermentation time and 0.05% inoculum size, respectively. Under optimal conditions, the biomass of Lactiplantibacillus plantarum NCU137 and sensory score of fermented goji reached to 8.84 ± 0.05 log CFU/g and 81.3 ± 1.5, respectively. After fermentation, the content of malate, succinic acid, and lactate increased, while the content of pyruvate, glucose, fructose, and the overall free amino acid decreased. After fermentation, volatile components except for the phenols and acids are declining. This study would provide theoretical basis and experimental data for the industrialization of Lycium barbarum fermentation. Novelty impact statement After Lactiplantibacillus plantarum NCU137 fermentation, the contents of organic acids and total acidity acid in fermented goji significantly increased, which could inhibit microbiological spoilage and growth. Moreover, we get a delicious fermented goji juice through the optimization of fermentation conditions. Therefore, the data obtained in this study provides a better understanding of the effects of raw material content, fermentation time, and inoculum size on the quality of fermented goji, which would be very beneficial for the production of high-quality fermented goji for subsequent consumption.

Small-molecule metabolome identifies potential therapeutic targets against COVID-19

Respiratory viruses are transmitted and acquired via the nasal mucosa, and thereby may influence the nasal metabolome composed of biochemical products produced by both host cells and microbes. Studies of the nasal metabolome demonstrate virus-specific changes that sometimes correlate with viral load and disease severity. Here, we evaluate the nasopharyngeal metabolome of COVID-19 infected individuals and report several small molecules that may be used as potential therapeutic targets. Specimens were tested by qRT-PCR with target primers for three viruses: Influenza A (INFA), respiratory syncytial virus (RSV), and SARS-CoV-2, along with unaffected controls. The nasopharyngeal metabolome was characterized using an LC–MS/MS-based screening kit capable of quantifying 141 analytes. A machine learning model identified 28 discriminating analytes and correctly categorized patients with a viral infection with an accuracy of 96% (R2 = 0.771, Q2 = 0.72). A second model identified 5 analytes to differentiate COVID19-infected patients from those with INFA or RSV with an accuracy of 85% (R2 = 0.442, Q2 = 0.301). Specifically, Lysophosphatidylcholines-a-C18:2 (LysoPCaC18:2) concentration was significantly increased in COVID19 patients (P < 0.0001), whereas beta-hydroxybutyric acid, Methionine sulfoxide, succinic acid, and carnosine concentrations were significantly decreased (P < 0.0001). This study demonstrates that COVID19 infection results in a unique nasopharyngeal metabolomic signature with carnosine and LysoPCaC18:2 as potential therapeutic targets.

I AD values of apricot (Prunus armeniaca L.) at harvest in relation to fruit quality and sensory properties during cold storage and shelf life

ABSTRACT DA-meter enables quick and non-invasive determination of fruit ripeness in different types of fruit, including apricots. In order to examine the postharvest physiology of apricots, fruits were divided into five I AD categories (0.00; 0.01−0.40; 0.41−0.80; 0.81−1.20; and >1.20) and were analyzed in terms of the physicochemical and sensory properties at harvest, after 21 days of cold storage and after 3 days of shelf life. The specified I AD categories differed in terms of ethylene production, flesh firmness, skin colour, composition and sensory properties at harvest. After cold storage and shelf life, ethylene production and respiration patterns, sensory properties, colour and fruit composition were affected by the I AD value. Fruit assigned to the categories I AD 0.81−1.20 and I AD >1.20 categories maintained higher firmness compared with the remaining three groups. Carotenoid, phenol, fructose, sucrose, citric and succinic acid content were affected by the I AD value during storage. Apricots attained optimal properties for consumption in different postharvest periods, depending on their maturity stage. These findings suggest that I AD-based segregation can support apricot fruit management during storage and shelf life.

Cytokinin and abscisic acid alleviate drought stress through changing organic acids profile, ion immolation, and fatty acid profile to improve yield of wheat (Triticum aestivum L.) cultivars.

There is an increasing interest for plant hormones to modulate the harmful effects of drought on crops. The present study was conducted to assess the effect of foliar-applied cytokin (CK) and abscisic acid (ABA) on yield, organic acids, minerals, and fatty acid profile of wheat (Triticum aestivum L.) cultivars (MV17 and Pishgam) in response to drought stress. The results showed drought significantly decreased grain yield and biomass, but they were enhanced by CK and ABA application. Acetic acid increased under drought stress conditions, and the remarkable increase (~ twofold) in succinic acid content was observed with ABA application under drought stress in MV17 cultivar. In general, droughtstress decreased malic acid, pyruvic acid, and citric acid, but CK enhanced them. The leaf accumulations of potassium (K+), calcium (Ca2+), magnesium (Mg2+), iron (Fe2+), and zinc (Zn2+) decreased by drought, where its reduction in MV17 was greater than Pishgam. However, an increased sodium (Na+) content was observed in plants experiencing drought with non-foliar application of ABA and CK. The plant growth hormones especially CK increased K+, Ca2+, Mg2+, Fe2+, and Zn2+, but decreased Na+. Fatty acid profile showed increased polyunsaturated fatty acids and monounsaturated fatty acids upon the drought stress. According to heat map, organic acids represented the maximum variations but fatty acids showed the minimum change during the treatments. The present study recommended foliar-applied CK to alleviate drought stress on wheat yield.

Antioxidant and anti-obesity effects of in vitro digesta of germinated buckwheat.

Buckwheat germinated on days of 3, 5, and 7 was digested in vitro, and the antioxidant and anti-obesity effects of the digesta were evaluated. In vitro digesta of 5 days germinated buckwheat (GBD5) showed significantly higher antioxidant activity in DPPH, ABTS, total phenolic content, total flavonoid content, and ferric reducing antioxidant power by 5.3, 1.3, 2.0, 3.2, and 2.8-fold, respectively than in vitro digesta of non-germinated buckwheat. GBD5 exerted inhibitory effect on total lipid accumulation in 3T3-L1 adipocyte in a dose-dependent manner, with over 25% reduction at 400 µg/mL. Additionally, GBD5 significantly downregulated genes related to adipocyte differentiation and fat accumulation. GBD5 possessed different metabolite profiles compared to others such as higher content of γ-aminobutyric acid and succinic acid. Therefore, GBD5 has potent antioxidant effects and suppresses fat accumulation-related genes and proteins expression, which could act as a new functional substance.

Improving sorghum digestion in broilers by targeting fermentation of xylan.

This study was to examine if it is possible to accelerate sorghum digestion in broiler chickens by targeting fermentation of the xylan. Cobb 500 broilers (n = 960, 80 birds per treatment) were fed 12 sorghum-soybean meal-based dietary treatments fed as 3 phases (starter d 0 to 12, grower d 13 to 23, finisher d 24 to 35), with 8 replicate pens of 10 birds per treatment. For half of the treatments (n = 6), 10% of the sorghum in the diet was directly replaced with 10% wheat bran, as a source of fermentable fibre. The diets were supplemented with either 0, 50 or 2,000 mg/kg xylo-oligosaccharides (XOS), with or without xylanase application. Body weight gain (BWG), feed intake (FI) and feed conversion corrected for mortality (cFCR) was determined at d 0 to 35, and male and female body weight were measured on d 35. On d 35, ileum and caeca samples were collected from 2 birds per pen, for determination of caecal cellulase and xylanase activity, microbiota composition and short chain fatty acid (SCFA) concentration, and ileal XOS concentration. Supplementation with 2,000 mg/kg XOS caused increased BWG at d 0 to 35 (P = 0.007) and enhanced caecal propionic, valeric and succinic acid concentration (P < 0.05). Wheat bran increased FI (P = 0.018) and BWG (P = 0.016), as well as caecal Bifidobacteria concentration (P < 0.001). Ileal XOS concentration was greatest when feeding combined wheat bran, 2,000 mg/kg XOS, and xylanase, resulting in increased caecal total SCFA, acetic acid and butyric acid concentration, and xylanase and cellulase activity (P < 0.05). Results from this study present that feed efficiency in birds fed sorghum-based diets is improved as a consequence of supplementing with fermentable fibre, xylanase and XOS.

Effect of KCl replacement of NaCl on fermentation kinetics, organic acids and sensory quality of sauerkraut from Northeast China

Northeast sauerkraut is widely consumed in north China in which organic acids have an important effect on its quality; while, northeast sauerkraut contains much sodium, which plays a key role in the fermentation of sauerkraut, it is not a benefit for health. Also, the aim of this study was to evaluate the effect of different proportions KCl replacement of NaCl on fermentation kinetics, organic acids, and sensory quality of northeast sauerkraut during the fermentation. The proportion of KCl had a significant impact on the fermentation kinetics, especially for kinetic parameters such as titratable acid (TTA) and reducing sugar (RS). The content of malic acid, acetic acid, lactic acid, and succinic acid in different treatments showed significant differences (p < .05). Meanwhile, the number of lactic acid bacteria (LAB) were also affected by KCl. According to quality descriptive analysis (QDA), the substitution ratio of KCl was no more than 50% to avoid the unacceptable taste and low overall liking. Practical applications The substitution ratio of KCl had an impact on the kinetics of sauerkraut fermentation, as well as the constituents of organic acids and sensory parameters of sauerkraut. Our study results will help to deepen the understanding of the influence of the KCl in sauerkraut production which provides some guidance in the production of sodium-reduction fermented vegetables.

Effect of ‘loss of function’ mutation in &lt;i&gt; SER1 &lt;/i&gt; in wine yeast: fermentation outcomes in co-inoculation with non-&lt;i&gt;Saccharomyces &lt;/i&gt;

In wine fermentation, improved wine complexity and sensorial properties can arise from the use of non-Saccharomyces yeast. Generally less alcohol tolerant, such strains often do not finish fermentation, therefore requiring a second inoculation with the more robust Saccharomyces cerevisiae, usually added on Day 3. This sequential approach affords non-Saccharomyces time to make an impact before being overtaken by S. cerevisiae. However, two inoculations are inconvenient; therefore the identification of a slow growing S. cerevisiae strain that can be used in a single co-inoculation with the non-Saccharomyces yeast is highly attractive. In this study we investigated the use of the naturally occurring ‘loss of function’ SER1 variant, identified in a Sake yeast, for the purposes of carrying out co-inoculated wine fermentations. The SER1-232(G &gt; C; G78R) change was introduced into the commonly used wine strain, EC1118, via CRISPR/Cas9 editing. In a chemically defined grape juice medium, the SER1(G78R) mutant grew and fermented more slowly and increased acetic acid, succinic acid and glycerol concentrations. Simultaneous inoculation with the slower-growing mutant with a Metschnikowia pulcherrima or Lachancea thermotolerans strain in sterile Sauvignon blanc juice resulted in differences in sensorial compounds, most likely derived from the presence of non-Saccharomyces yeasts. The EC1118 SER1 (G78R) mutant completed fermentation with M. pulcherrima, MP2, and in fact improved the viability of MP2 compared to when it was used as a monoculture. The SER1 (G78R) mutant also promoted both the growth of the SO2-sensitive L. thermotolerans strain, Viniflora® Concerto™, in a juice high in SO2 and its subsequent dominance during fermentation. In co-fermentations with wild-type EC1118, the Concerto™ population was substantially reduced with no significant changes in wine properties. This research adds to our understanding of the use of a novel slow-growing S. cerevisiae yeast in wine fermentations co-inoculated with non-Saccharomyces strains.

Succinic acid recovery from a glycerol-based solution using phosphonium ionic liquids supported by COSMO-RS

Succinic acid has been considered a promising chemical building block that can be bio-produced using renewable resources. However, one of the biggest challenges in the bioproduction of this acid is the extraction and purification process. Currently, to extract and improve the purity of the produced succinic acid, a liquid-liquid extraction using organic solvents and extractants is performed.In this work, a liquid-liquid extraction of succinic acid from a model fermentation solution of Yarrowia lipolytica yeast broth (succinic acid + glycerol + water) is studied. The liquid-liquid extraction was carried out using hydrophobic phosphonium-based ionic liquids as extractants, for a 1:1 phase-volume ratio during 24 h at two different temperatures (298.15 K and 310.15 K) measuring the differences in the concentration of succinic acid and glycerol in the aqueous feed phase after 24 h to quantify the extraction percentage and, the succinic acid / glycerol selectivity. To obtain the succinic acid /water selectivity, the water concentration in the IL phase was calculated using Karl Fischer titration. With an extraction percentage of 78.4% for succinic acid and, a selectivity of 103 and 157 respectively for succinic acid /water and succinic acid /glycerol at 310.15 K, the best studied ionic liquid was [P6,6,6,14][PHOS] being 10 times higher than octanol, which is commonly used as a comparative conventional solvent. On the other hand, a molecular simulation of liquid-liquid extraction generated in COSMO-RS, allowed to validate the experimental results, also indicating that the strong hydrogen bond interactions of [P6,6,6,14][PHOS] and succinic acid were responsible for the excellent values obtained. Finally, the dissolved succinic acid in the organic phase was easily removed with an ultra-pure water striping using liquid-liquid extraction at 298.15 K for 40 min with a 1:1 phase-volume ratio.

Isolation, Identification and Antibacterial Mechanism of the Main Antibacterial Component from Pickled and Dried Mustard (Brassica juncea Coss. var. foliosa Bailey)

Our previous study showed that the ethyl acetate fraction (EAF) from an ethanolic extract of pickled and dried mustard (Brassica juncea Coss. var. foliosa Bailey) had significant antibacterial activity. Here, the EAF was further separated into seven sub-fractions by silica gel column chromatography. The antibacterial activities of the EAF and its sub-fractions against Staphylococcus aureus and Pseudomonas fluorescens were assessed using the agar diffusion method and double dilution method. Among the seven sub-fractions, the third sub-fraction (Fr 3) possessed the strongest antibacterial activity. The main component in Fr 3 was identified by GC-MS, UV-vis, FT-IR, HPLC, 1H NMR and 13C NMR techniques, and was found to be succinic acid. The content of succinic acid in Fr 3 was determined as 88.68% (w/w) by HPLC. Finally, the antibacterial mechanism of succinic acid against the tested strains was explored by determining the intracellular component leakage, measuring the cell particle size and observing the cell morphology. The results showed that succinic acid could damage the cell membrane structure and intracellular structure to increase the leakage of cell components and reduce the cell particle size. Our results suggest that succinic acid could be used in food industry to control bacterial contamination by S. aureus and P. fluorescens.

Transcriptomics and metabolomics analyses identified key genes associated with sugar and acid metabolism in sweet and sour pomegranate cultivars during the developmental period

Pomegranate (Punica granatum), an important fruit tree in the world, is rich in bioactive substances and has broad prospects for development. In this study, gene expression levels and the concentrations of metabolites involved in the metabolism of soluble sugars and organic acids were investigated in sweet and sour pomegranate cultivars at the S1 (July 25) stage, S2 (August 26) stage, and S3 (September 24) stage. The results showed that glucose, fructose, citric acid, and malic acid were predominantly present in pomegranate. The expression of invertase 2 (INV2), INV1, FRK2, FRK7, PFK2, PFK7, and HK1 was closely correlated with the fructose and glucose contents during different developmental stages, whereas the expression of sucrose synthase 3 (SUS3) and INV1 was negatively correlated with the sucrose content. The expression of MDH (c28468_g3) and WRKY42 (c20711_g1) genes were closely related to the content of sucrose, malic acid, citric acid, and succinic acid during different developmental stages. Gene expression and metabolite concentrations varied between the two cultivars. The results provide valuable information for gene discovery, marker-assisted selection, and investigation of metabolism mechanisms in pomegranate fruits.

The fermented soy whey produced by a combined lactic acid bacteria starter shows improved flavor and the function in alleviating dextran sulphate sodium induced colitis in mice

ABSTRACT In this study, Lactiplantibacillus plantarum BC299, Lactobacillus delbrueckii subsp. bulgaricus 717 and Streptococcus thermophilus 176 were used as combined starter cultures to produce a fermented soy whey beverage. The results showed that the fermentation of the combined starter cultures increased the content of lactic acid, acetic acid, succinic acid, and malic acid, while decreased the content of citric acid, fumaric acid and propionic acid. Meanwhile, the fermentation also effectively changed the proportion of volatile flavor substances. The higher sensory score of the fermented soy whey also confirmed the flavor improvement effect of the combined starter cultures. In addition, the in vivo results of animal experiments showed that the fermented soy whey could significantly improve the disease activity index (DAI) and colon morphology in dextran sulfate sodium (DSS) induced colitis mice. This study showed that the combined lactic acid bacteria starter cultures had important value-added relevance on the effective reuse of the soy whey by-product.

Characterization of Taste Compounds and Sensory Evaluation of Soup Cooked with Sheep Tail Fat and Prickly Ash.

Sheep tail fat and prickly ash play an important role in improving the umami taste of mutton soup. In this work, the effects of prickly ash on key taste compounds in stewed sheep tail fat soup were investigated. Results showed that the taste intensity of sheep tail fat soup cooked with 0.2% prickly ash increased significantly. The concentration of organic acids and free amino acids in sheep tail fat soup significantly increased with the addition of prickly ash. The concentration of succinic acid (2.637 to 4.580 mg/g) and Thr (2.558 to 12.466 mg/g) increased the most among organic acids and amino acids, respectively. Spearman’s correlation analysis elucidated that seven taste compounds were positively correlated (correlation coefficient > 0.7) with the overall taste intensity of the soup sample including Thr, Asp, oxalic acid, lactic acid, citric acid, succinic acid, and ascorbic acid. Additional experiments and quantitative descriptive analysis further confirmed that Asp, lactic acid and citric acid were the key taste compounds to improve saltiness and umami taste in sheep tail fat soup with prickly ash.

Succinic Acid Based Particles as Carriers of Volatile Substances

Volatile substances are in high demand, especially in cosmetic and pharmaceutical applications. To prolong their shelf-life and prevent their degradation if exposed to air, these volatile substances are often encapsulated. Most frequently, matrix materials are composed of high-molecular-weight polymers because some of them can efficiently retain volatiles and meet the safety requirements these applications impose. However, these substances must be processed at high concentrations, resulting in viscous solutions that are difficult to spray or emulsify. To address this shortcoming, we employed a low-molecular-weight substance, succinic acid, as a matrix material to encapsulate a model volatile, vanillin. To facilitate the encapsulation of low-molecular-weight substances, such as volatiles, we produce these particles through surface acoustic wave (SAW)-based microfluidic spray-drying. This technique forms drops with diameters as small as 1–10 μm that dry within a few hundred ms. Thereby, we can kinetically arrest or even suppress phase separations. We demonstrate that vanillin is most efficiently encapsulated and retained over a prolonged time if succinic acid is formulated from solutions initially containing succinic acid concentrations exceeding 10% of its saturation concentration. If appropriately formulated, these succinic acid based particles retain volatiles longer than the much more commonly employed high-molecular-weight dextrin. These results open up a new avenue to encapsulate volatiles in low-molecular-weight compounds that pack more densely than high-molecular-weight counterparts and therefore can retain volatiles for a prolonged time.

Co-production of acetoin and succinic acid using corncob hydrolysate by engineered Enterobacter cloacae

To improve the synthesis of succinic acid and acetoin, 2,3-butanediol dehydrogenase, lactate dehydrogenase, pyruvate formate-lyase, and glucose transporter EIIBCGlc genes were deleted from the Enterobacter cloacae genome to construct the CL82 strain. The CL82 strain co-production concentrations of succinic acid and acetoin from glucose within 48 h were 15.41 and 36.95 g L-1, the succinic acid and acetoin productivity were 0.32 and 0.77 g L-1h−1, respectively, and the amount of added bicarbonate was reduced by 38.6%. Moreover, CL82 can also co-utilize glucose and xylose for the co-production of succinic acid and acetoin during fermentation. CL82 can also utilize corncob hydrolysate for the co-production of succinic acid and acetoin. The engineering strategy presented herein can provide a practical approach for the utilization of renewable feedstocks foe the simultaneous production of two commercial products using CL82, which helps to reduce the cost of microbial fermentation.

Use of non-conventional yeasts to increase total acidity in the Cava base wines

In recent years, climate change has strongly influenced viticulture, with a higher concentration of sugars in grapes, a lower concentration of organic acids and, therefore, increases in alcohol concentration and pH. This work aimed to increase the concentration of organic acids and total acidity in Cava base wine with different commercial strains: Saccharomyces cerevisiae (IO), a hybrid S. cerevisiae x S. uvarum (VE) and Lachancea thermotolerans (LA). Several laboratory and industrial fermentations were carried out with Macabeo must. Our results show that strains VE and LA are capable of producing high concentrations of succinic acid and lactic acid, respectively. The initial amount of nitrogen in grape must directly influences the production of these acids. By adopting different inoculation strategies, the co-inoculation of LA + VE brings about a significant increase in total wine acidity. The results also reveal that LA has excellent fermentative capacity when the initial SO2 concentration is low and the competitive ability of LA against the VE hybrid is good. In short, our results demonstrate that using strains LA and VE acts as a microbiological strategy to increase total acidity and to lower the pH of Cava base wines.

A preliminary study on change of mistletoe (Viscum albüm L.) silage quality according to collection time and host tree species

In this study, it was aimed to determine the silage quality of mistletoe (Viscum album L.) collected from wild pear (Pyrus amygdaliformis) and poplar trees (Populus canadensis) in January, July, August, and December. The fresh samples were chopped in 2 cm size and ensiled in 2 kg plastic bags then stored at 25 ± 2 °C conditions for 45 days. Silage samples were investigated for dry matter ratio, pH, crude protein ratio, crude ash ratio, condensed tannin, acid detergent fiber, neutral detergent fiber, lactic acid, acetic acid, butyric acid, malic acid, citric acid, succinic acid, potassium, phosphorus, calcium, and magnesium contents. All quality traits of mistletoe silages were significantly different between host trees, collected times, and the interactions of host tree x collection time. It has been determined that mistletoe can be used as silage in terms of all the traits investigated. Besides, the silage of mistletoe collected from wild pear in December is better than other treatments. Mistletoe can be considered as an alternative roughage source due to its high content of crude protein, nutrient composition, easy digestibility, and organic acid content.

Acid hydrolysis of sucrose in sweet sorghum syrup followed by succinic acid production using a genetically engineered Escherichia coli

Acid hydrolysis of sucrose was studied as a method to convert sucrose in sweet sorghum syrup into glucose and fructose before fermentation with the genetically engineered succinic acid-producing Escherichia coli strain AFP184. Successful hydrolysis of sucrose in sweet sorghum syrup was achieved without noticeable formation of degradation products using moderate temperatures, 65–85 °C, with 0.24–0.48 M HCl in less than 30 min. The measured sucrose hydrolysis rates were lower than previously reported for sweet sorghum molasses. The E. coli strain AFP184 consumed all the sugars (glucose and fructose) in the sweet sorghum syrup hydrolysate. The products were predominately succinic and acetic acid. The final concentration of succinic acid was 27 g/L, but the organism was shown to produce higher levels of succinic acid (60 g/L), when grown under optimal conditions on pure glucose. Note that the fermentation results during scale-up should be seen as preliminary, as initial sugar content, aeration, agitation, and duration of initial aerobic growth phase were not optimized. Thus, improved results closer to those experienced with glucose are expected.

Qualitative characteristics of collectible forms Citrus reticulata Blan. var. unchiu Tan.

The article discusses the key characteristics of the quality of mandarin fruits (Citrus reticulata Blan. var. unchiu Tan.) from the collection of FRC SSC RAS. The objects of the study were 12 unique and most valuable varieties and hybrids of domestic and foreign breeding. The results of mechanical analysis of fruits are given. The study of the chemical composition of fruits showed that they are rich in vitamins, sugars, acids. The quantitative ratio is dominated by sucrose, more than 70 % of sucrose is noted in the varieties 'Pioner 80', 'Sochinskij 23', 'Krasnodarskij 83', 'Iverija'. The greatest amount of fructose was isolated in clones and hybrids from 20.1 – 21.6 %. Organic acids (citric, malic, succinic, acetic, lactic, oxalic, ascorbic), vitamin C (ascorbic) were determined, the high content of which was noted in clones 22 and 33. Among the main organic acids, citric acid dominates – 90-96 %, the leader appear to be 'Kowano Wase', the least amount is in ' Sochinskij 23'. The high content of succinic acid was noted in the varieties 'Millennium 1' (37.34 mg/100g) and ' Pioner 80' (35.06 mg/100g). Fruits of the variety 'Jubilejnyj', ' Pioner 80' and Hybrid No. 10 contain the largest amount of tartaric acid, which ranges from 51.44 to 59.71 mg/100g. The highest sugar–acid index was noted in the early ripening varieties 'Millenium 1' (9.3 units) and 'Kowano Wase' (8.5 units), hybrid No. 10 (8.0 units), which indicates good taste indicators of these samples.