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1.
Biochemical characterization of black and green mutant elderberry during fruit ripening
Maja Mikulič Petkovšek, Anton Ivančič, Saša Gačnik, Robert Veberič, Metka Hudina, Silvija Marinovic, Christian Molitor, Heidi Halbwirth, 2023, izvirni znanstveni članek

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
.pdf Celotno besedilo (2,29 MB)
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2.
The Darker the better : Identification of chemotype profile in soroses of local and introduced mulberry varieties with respect to the colour type
Andreja Urbanek Krajnc, Jan Senekovič, Silvia Cappellozza, Maja Mikulič Petkovšek, 2023, izvirni znanstveni članek

Opis: Mulberries are the "essence of the past", the so-called Proust effect, for the inhabitants of the sericultural regions who enthusiastically remember feeding silkworms with mulberry leaves and picking the different coloured fruits that were their favourite sweets in childhood. To determine the chemistry behind the colour and taste of mulberry soroses, the main metabolites of the local and introduced varieties were studied. The soroses were classified into five different colour types and the size parameters were determined. The main sugars identified were glucose and fructose, while the predominant organic acids were citric and malic acids, which were highest in the darker varieties, and fumaric and tartaric acids, which were highest in the lighter varieties. A total of 42 phenolic compounds were identified. The predominant phenolic acid was chlorogenic acid, followed by other caffeoylquinic acids and coumaroylquinic acids. The predominant anthocyanins were cyanidin-3-glucoside and cyanidin-3-rutinoside. According to PCA analysis, the colour types showed a clear chemotype character. The sweet taste of the yellowish-white soroses was defined by 49% fructose, followed by 45% glucose and 6% organic acids. The sour character of the black genotypes was characterised by a lower sugar and higher (11%) organic acid content. The colour- and species-dependent effect was observed in the proportion of caffeoylquinic acids and quercetin glycosides, which decreased with increasing colour intensity from 60% of the total to 7%, and from 17% to 1%, respectively. An upward trend was observed for flavanols (5% to 29%) and anthocyanins, which accounted for 62% of the total phenolics in black varieties. This article gives an insight into the metabolite composition of mulberry soroses as the sweets of choice between light and sweet and dark and sour.
Ključne besede: mulberry soroses, sugars, organic acids, phenolics, anthocyannins
Objavljeno v DKUM: 20.02.2024; Ogledov: 380; Prenosov: 29
.pdf Celotno besedilo (1,34 MB)
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3.
Bio-based processes for material and energy production from waste streams under acidic conditions
Zeynep Cetecioglu, Merve Atasoy, Adam Cenian, Gaweł Sołowski, Janja Trček, Aysenur Ugurlu, Jana Sedlakova-Kadukova, 2022, pregledni znanstveni članek

Opis: The revolutionary transformation from petrol-based production to bio-based production is becoming urgent in line with the rapid industrialization, depleting resources, and deterioration of the ecosystem. Bio-based production from waste-streams is offering a sustainable and environmentally friendly solution. It offers several advantages, such as a longer operation period, less competition for microorganisms, higher efficiency, and finally, lower process costs. In the current study, several biobased products (organic acids, biomethane, biohydrogen, and metal leachates) produced under acidic conditions are reviewed regarding their microbial pathways, processes, and operational conditions. Furthermore, the limitations both in the production process and in the scale-up are evaluated with future recommendations.
Ključne besede: bio-based production, acidogenic conditions, fermentation, organic acids, biohydrogen, biomethane, bioleaching
Objavljeno v DKUM: 24.08.2023; Ogledov: 351; Prenosov: 50
.pdf Celotno besedilo (1,39 MB)
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4.
IN VIVO TIME ANALYSIS OF THE DYNAMICS OF QUALITY DEVELOPMENT IN RIPENING APPLE FRUIT
Nadja Sadar, 2013, doktorska disertacija

Opis: Colour and taste are important attributes of apple fruit quality that is generated during the fruit-growing period. Despite a plethora of studies dealing with this topic, the detailed information on how quality is generated is, however, still lacking. This is because traditionally, the obtained agro-morphological and biochemical data are analysed with empirical models using mean values of large samples, without taking the effects of biological variation into account, thus completely masking the spatio-temporal physiological mechanisms. To really understand quality, its generation during fruit growth needs to be monitored and modelled. When knowledge exists on the type and kinetics of the processes involved, the variation in properties can be described and taken into account by using so-called fundamental models, built on theoretical considerations. To understand the behaviour and the variation of colour and taste compounds, within or between individual fruits, and to assess their importance throughout the food supply chain, it is therefore important to understand the dynamics of these compounds during growth. The study consisted of (1) a preliminary experiment, aiming to determine the suitability of the semi-destructive biopsy sampling technique for in-vivo monitoring of certain metabolites during apple fruit development on a tree, (2) an experiment on spatial distribution, and (3) an experiment on temporal distribution of metabolites and colour in developing individual apple fruit. The experiment on spatial distribution was conducted to determine the effect of location on the accumulation of the individual quality components within apple fruit, and the parallel temporal experiment was conducted to monitor the dynamics and mechanisms of these components in apple fruit during on the tree development. Diameter and standard maturity indices of fruit flesh firmness, soluble solids content, starch degradation index, titratable acidity, and Streif maturity index were also determined, to obtain relations between individual quality components. Colour descriptors (L*, a* b*), individual sugars (fructose, sucrose, glucose), sorbitol, and individual organic acids (malic, citric, shikimic, fumaric) were monitored from 40 and 54 days before to 16 and 32 days after the optimum maturity for long term storage on individual apples of cv. ‘Gala’ and cv. ‘Pinova’. Data were analysed with classic empirical statistics as well as with non-linear indexed regression, based on process oriented models, which included biological variation between apples of the same batch. Frequently probelation and quantile regression were applied. The results of the preliminary experiment confirmed that the novel biopsy sampling technique is suitable for in-vivo monitoring of the spatio-temporal distribution of colour and individual taste components during on-tree apple fruit development. In the results from the experiment on spatial distribution, a sinusoidal distribution over locations at 70° above the fruit equator was observed for all the monitored quality components. Descriptor a* was highest at the blush, and b* and L* at the shaded side of the fruit. Citric acid preferentially accumulated at the shaded side of the fruit, whereas fructose in cv. ‘Gala’ tended to accumulate at the blush. Other metabolites were more or less equally distributed within fruit. The results of longitudinal monitoring reveal a sigmoidal increase of a*, an exponential increase of diameter and sugars, and an exponential decrease of organic acids over time. In both cultivars, large variations were observed between individual fruit for all the monitored quality components. When analysed with non-linear indexed regression, based on process-oriented models, and after the probelation combined with quantile regression, the explained parts of the majority of the monitored quality components were well above 90 %. The mechanism of colour development was the same for both cultivars. The biological shift factor for all metabolites and colour had roughly the same value within cultiv
Ključne besede: apple fruit, colour, models, organic acids, spatio-temporal monitoring, sugars
Objavljeno v DKUM: 19.12.2013; Ogledov: 3040; Prenosov: 307
.pdf Celotno besedilo (3,87 MB)

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