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Opis: Plant waste materials are important sources of bioactive compounds with remarkable health-promoting benefits. In particular, industrial by-products such as mango peels are sustainable sources of bioactive substances, with antioxidant, enzymatic, and antimicrobial activity. Appropriate processing is essential to obtain highly bioactive compounds for further use in generating value-added products for the food industry. The objective of the study was to investigate and compare the biological activity of compounds from fresh and dried mango peels obtained by different conventional methods and unconventional extraction methods using supercritical fluids (SFE). The highest total phenolic content (25.0 mg GAE/g DW) and the total content of eight phenolic compounds (829.92 µg/g DW) determined by LC-MS/MS were detected in dried mango peel extract obtained by the Soxhlet process (SE). SFE gave the highest content of proanthocyanidins (0.4 mg PAC/g DW). The ethanolic ultrasonic process (UAE) provided the highest antioxidant activity of the product (82.4%) using DPPH radical scavenging activity and total protein content (2.95 mg protein/g DW). Overall, the dried mango peels were richer in bioactive compounds (caffeic acid, chlorogenic acid, gallic acid, catechin, and hesperidin/neohesperidin), indicating successful preservation during air drying. Furthermore, outstanding polyphenol oxidase, superoxide dismutase (SOD), and lipase activities were detected in mango peel extracts. This is the first study in which remarkable antibacterial activities against the growth of Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) were evaluated by determining the microbial growth inhibition rate after 12 and 24 h incubation periods for mango peel extracts obtained by different methods. Ethanolic SE and UAE extracts from dried mango peels resulted in the lowest minimum inhibitory concentrations (MIC90) for all bacterial species tested. Mango peels are remarkable waste products that could contribute to the sustainable development of exceptional products with high-added value for various applications, especially as dietary supplements.
Ključne besede: mangifera indica, peels, bioactive substances, LC-MS/MS, proteins, enzymes, antibacterial activity
Objavljeno v DKUM: 12.08.2024; Ogledov: 104; Prenosov: 8
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Opis: The content of sugars, organic acids, phenolic compounds and selected enzyme activities in the anthocyanin pathway were analyzed in NIGRA (Sambucus nigra var. nigra—black fruits) and VIRIDIS (S. nigra var. viridis—green fruits) fruits over four stages of ripening. The share of glucose and fructose in green fruits was higher than in colored fruits, and the sugar content increased significantly until the third developmental stage. Ripe NIGRA berries had 47% flavonol glycosides, 34% anthocyanins, 3% hydroxycinnamic acids and 14% flavanols, whereas the major phenolic group in the VIRIDIS fruits, making up 88% of the total analyzed polyphenols, was flavonols. NIGRA fruits were rich in anthocyanins (6020 [mi]g g$^{-1}$ FW), showing strong activation of the late anthocyanin pathway (dihydroflavonol 4-reductase, anthocyanidin synthase). In both color types, phenylalanine ammonia lyase and chalcone synthase/chalcone isomerase activities were highest in the first stage and decreased during ripening. In VIRIDIS fruit, no anthocyanins and only one flavanol (procyanidin dimer) were found. This was most likely caused by a lack of induction of the late anthocyanin pathway in the last period of fruit ripening. The VIRIDIS genotype may be useful in studying the regulatory structures of anthocyanin biosynthesis and the contribution of distinct flavonoid classes to the health benefits of elderberries.
Ključne besede: black elderberry, Sambucus nigra, green genotype, polyphenolics, sugars, organic acids, phenylpropanoid enzymes
Objavljeno v DKUM: 28.03.2024; Ogledov: 208; Prenosov: 16
Celotno besedilo (2,29 MB)
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Opis: The purpose of this master's thesis was to determine the ability of certain organisms of the kingdom Fungi to produce a series of enzymes in their active form by solid-state fermentation. In this study, two types of fungi were used, Pleurotus ostreatus and Ganoderma lucidum. For this purpose, different growth media, cultivation times (8 and 10 days), extraction procedures (shaking and homogenization) and extraction medium (distilled water, sodium citrate buffer and sodium phosphate buffer) were used. First, for P. ostreatus mushroom, the optimization of the extraction procedure and time for isolation of enzymes in their active form (α-amylase, glucoamylase, cellulase, laccase, and protease) was studied. It was observed that the highest total protein concentration in mycelium extract was obtained by 8 min of homogenization (0.8607 mg/mL, and distilled water). Using the shaking procedure, the highest enzyme activities were achieved for α-amylase (24 h, 8.0413 U/mL, and sodium citrate buffer) and protease (3 h, 0.0040 U/mL, and sodium citrate buffer). With the homogenization process, the highest activities were achieved for the enzymes glucoamylase (10 min, 6.7113 U/mL, and sodium citrate buffer) and laccase (8 min, 12.2500 U/mL, and sodium citate buffer). For the mushroom G. lucidum, the growth medium and the extraction procedure were optimized, using the same extraction medium (sodium citrate buffer). In this case, α-amylase, glucoamylase, cellulase, laccase, protease, catalase, peroxidase, superoxidase dismutase (SOD), and lipase were studied. It was observed that the highest total protein concentration was obtained with 4 min of homogenization (0.0338 mg/mL). Furthermore, using the homogenization process, the highest activities were achieved for α-amylase (4 min, 16.3459 U/mL) and SOD (4 min, 9.2615 U/mL). With the shaking procedure, the highest activities were achieved for cellulase (3 h, 1.6332 U/mL), lipase (3 h, 16.924 U/mL), glucoamylase (3 h, 14.6737 U/mL), peroxidase (3 h, 0.0156 U/mL), protease (3 h, 0.0080 U/mL) and laccase (24 h, 20.7083 U/mL).
Ključne besede: medicinal mushrooms, Pleurotus ostreatus, Ganoderma lucidum, total proteins, enzymes activities.
Objavljeno v DKUM: 06.07.2022; Ogledov: 1836; Prenosov: 42
Celotno besedilo (2,56 MB)

Opis: Fatty ester synthesis with immobilized 1,3-specific lipase from Mucor Miehei is described. 1,2-Isopropylidene glycerol was peoduced by condensation of glycerol with acetone was esterified with oleic acid in the presence of a Mucor Miehei lipaze (Lipozyme TM) to obtain 1,2 isopropylidene- 3-oleoyl glycerol. The effects of various process parameters (temperature and pressure)and various ratios (enzyme/substrate) have been investigated to determine optimal conditions for the esterification process. The highest conversion of oleic acid (80% w/w) was obtained at 55 oC and 57.057 bar, while the optimal addition of lipase to substrate was determined to be 0,096 g per gram of reaction mixture. The esterification can be modelled successfully as a reverse second order reaction. Thermodynamic properties of the reaction system at 55 oC and 0.057 bar were also determined. Activation energy was 20.82 kJ/mole, entropy of activation -0,26 kJ/(Kmole) and free energy of activation was 103.32 kJ/mole.
Ključne besede: chemical engineering, biotechnology, esterification, syntheses, esters, enzymes, lipase, Mucor miehei, reaction kinetics, reaction thermodynamics, 1, 2-isopropylidene-3-oleoyl glycerol
Objavljeno v DKUM: 06.06.2012; Ogledov: 2549; Prenosov: 100
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Opis: Ischnoderma resinosum produced extracellular ligninolytic enzymes laccase and MnP. The activity of laccase achieved the maximum on day 10 (29.4 U L-1), the MnP on day 14 (34.5 U L-1). Laccase and Mn-peroxidase were purified from the culture liquid using gel permeation and ion-exchange chromatographies. Purified Mn-peroxidase performed decolorization of all textile dyes tested (Reactive Black 5, Reactive Blue 19, Reactive Red 22 and Reactive Yellow 15). Laccase was inactive with Reactive Black 5 and Reactive Red 22, while all dyes were decolorized after addition of the redox mediators violuric acid (VA) and hydroxybenzotriazole (HBT). The culture liquid from I. resinosum cultures was also able to decolorize all dyes as well as the synthetic dyebaths in the presence of VA and HBT. The highest decolorization rates were detected in acidic pH (3-4).
Ključne besede: Ischnoderma resinosum, Basidiomycetes, Laccase, Mn-peroxidase, Textile dyes, ligninolytic enzymes
Objavljeno v DKUM: 01.06.2012; Ogledov: 1971; Prenosov: 91
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