Publications by authors named "Sandra Voća"

10 Publications

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Ultrasound as a Promising Tool for the Green Extraction of Specialized Metabolites from Some Culinary Spices.

Molecules 2021 Mar 25;26(7). Epub 2021 Mar 25.

Faculty of Agriculture, University of Zagreb, Svetošimunska cesta 25, 10000 Zagreb, Croatia.

Spices are a popular food of plant origin, rich in various phytochemicals and recognized for their numerous properties. The aim of the study was to evaluate the antioxidant and antimicrobial activity, as well as the content of specialized metabolites, of aqueous extracts of three spice species--garlic ( L.), ginger ( L.) and turmeric ( L.)--prepared by green extraction methods. Ultrasound treatment increased the chromaticity parameter b value of turmeric and ginger extracts, thus indicating a higher yellow color predominantly due to curcuminoids characteristic of these species. Ultrasound-assisted extraction significantly increased the content of total soluble solids, phenolic compounds, total carotenoids and vitamin C. The temperature of the system was also an important factor, with the highest (70 °C) conditions in ultrasound-assisted extraction having a positive effect on thermolabile compounds (vitamin C, phenolics, total carotenoids). For example, turmeric extract treated with ultrasound at 70 °C had up to a 67% higher vitamin C content and a 69.4% higher total carotenoid content compared to samples treated conventionally at the same temperature, while ginger extracts had up to 40% higher total phenols. All different concentrations of spice extracts were not sufficient for complete inhibition of pathogenic bacterial strains of , and ; however, only garlic extracts had an effect on slowing down the growth and number of colonies. Spice extracts obtained by ultrasonic treatment contained a significantly higher level of bioactive compounds and antioxidant capacity, suggesting that the extracts obtained have significant nutritional potential and thus a significant possibility for phytotherapeutic uses.
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http://dx.doi.org/10.3390/molecules26071866DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8037095PMC
March 2021

Biological Potential of Fruit and Leaves of Strawberry Tree ( L.) from Croatia.

Molecules 2020 Nov 3;25(21). Epub 2020 Nov 3.

Department of Pomology, Faculty of Agriculture, University of Zagreb, Svetošimunska cesta 25, 10000 Zagreb, Croatia.

The strawberry tree fruit and leaf are a rich source of minerals, easily digestible sugars, dietary fibers, vitamins (especially vitamin C) and many bioactive compounds of significant functional value. Due to their favorable chemical composition, fruits have recently become increasingly popular in consumption. The aim of this study was to determine the physical-chemical composition, content of bioactive compounds, and also the antioxidant capacity of the fruit and leaves of wild strawberry tree populations among the Adriatic coast in Croatia, as well as to investigate the influence of location on the content of specific bioactive compounds. According to the obtained results, both fruit and leaves are pronouncedly high in vitamin C content, the average value for fruits amounted to 224.21 mg/100 g FW, while that for leaves amounted to 138.08 mg/100 g FW. Additionally, significantly high values of total polyphenolic compounds were recorded both in fruits (average value of 637.94 mg GAE/100 g FW) and especially in leaves (average value of 2157.01 mg GAE/100 g FW). Several pigments from different categories were determined in the fruit depending on fruit maturity, including: total anthocyanins, β-carotene and lycopene; while in leaves chlorophylls and carotenoids. Given the high content of different bioactive compounds high values of antioxidant capacity were determined (the average value for fruits was 2269.96 µmol TE/kg and for leaves, 2237.16 µmol TE/kg). Location strongly influenced the physical-chemical composition and also the content of specialized metabolites; populations collected from southern areas (central and south Dalmatia) of the Adriatic coast tended to have higher amounts of vitamin C, total phenols, total anthocyanins and β-carotene.
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http://dx.doi.org/10.3390/molecules25215102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663455PMC
November 2020

Effect of Different Green Extraction Methods and Solvents on Bioactive Components of Chamomile ( L.) Flowers.

Molecules 2020 Feb 13;25(4). Epub 2020 Feb 13.

Faculty of Agriculture, University of Zagreb, Svetošimunska Cesta 25, 10000 Zagreb, Croatia.

Chamomile ( L.) dried flowers contain a group of interesting biologically active compounds such as sesquiterpenes, flavonoids, coumarins, vitamins, phenolic acids and glucosides. Therefore, the aim of the present study was to characterize the composition in bioactive compounds (specialized metabolites) present in water and ethanol extracts of chamomile flowers, together with monitoring the impact of different extraction techniques (conventional vs. ultrasound-assisted extraction (UAE)) on the parameters under investigation. UAE treatment significantly decreased the extraction time of bioactive compounds from herbal material. Polyphenolic compounds content and antioxidant capacity were significantly higher in UAE extracts. Moreover, solvent type had a significant impact on the specialized metabolites content, while the highest vitamin C and polyphenols content were recorded in 50% ethanol (/) extracts. Optimization of basic extraction factors: solvent type, temperature and technique is crucial for obtaining the extracts with the highest content of specialized metabolites and antioxidant capacity.
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http://dx.doi.org/10.3390/molecules25040810DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7070460PMC
February 2020

Traditional, Indigenous Apple Varieties, a Fruit with Potential for Beneficial Effects: Their Quality Traits and Bioactive Polyphenol Contents.

Foods 2020 Jan 5;9(1). Epub 2020 Jan 5.

Faculty of Agriculture, University of Zagreb, HR 10000 Zagreb, Croatia.

Earlier studies suggested that traditional apple varieties have quality traits well accepted by consumers and beneficial effects on human health. The aim was to collect 25 traditional apple varieties grown in Croatia and to determine, for the first time in so many details, their external (weight, height, width, shape, color), internal quality traits (firmness, starch decomposition index, maturity index, soluble solid concentration, total acids, soluble solid/total acids ratio, pH), and seed characteristics. In addition, individual polyphenols were determined in the flesh and peel, by using RP-HPLC. All was compared to the commercial variety 'Idared'. Quality parameters of these varieties were similar to those of the commercial variety. The flesh and peel contained flavan-3-ols, dihydrochalcones, phenolic acids, and flavonols, while anthocyanins were additionally found in the peel. Total polyphenols in the peel (536-3801 mg kg fresh weight (FW)) and in the flesh (79-1294 mg kg FW) of the majority of varieties were higher than in the commercial variety. Principal component analysis showed possible clustering according to polyphenol amounts. According to the observed diversity of quality traits and bioactive polyphenol contents, the traditional varieties have potential for consumer acceptance and increased cultivation.
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http://dx.doi.org/10.3390/foods9010052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7022233PMC
January 2020

Effect of ultrasound pre-treatment and drying method on specialized metabolites of honeyberry fruits (Lonicera caerulea var. kamtschatica).

Ultrason Sonochem 2019 Sep 23;56:372-377. Epub 2019 Apr 23.

University of Zagreb, Faculty of Food Technology and Biotechnology, Pierottijeva ulica 6, 10000 Zagreb, Croatia. Electronic address:

Honeyberries are rich in various nutrients (eg. minerals, and vitamins) and bioactive compounds (eg. polyphenols). The aim of the study was to evaluate the impact of ultrasound (USN) pre-treatment (100% power at 37 kHz) at 40 °C for 3 min and drying techniques (conduction or vacuum) on nutritional composition and bioactive compounds of honeyberry fruits. The evaluation of dried barriers revealed that both USN pre-treatment and drying techniques affected the composition of the final product. The highest vitamin C content (1.067-1.187 mg 100 g DM) was found in fruit samples pre-treated by USN, regardless of the drying technology used. The highest total phenol (2.445 mg GAE 100 g DM), total flavonoid (0.939 mg GAE 100 g DM), total non-flavonoid (1.506 mg GAE 100 g DM) and anthocyanin content (2.334 mg kg FW) were obtained in fruits after applying USN pre-treatment and vacuum dried at 40 °C.
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http://dx.doi.org/10.1016/j.ultsonch.2019.04.034DOI Listing
September 2019

Evaluation of the Behavior of Phenolic Compounds and Steviol Glycosides of Sonicated Strawberry Juice Sweetened with Stevia ( Bertoni).

Molecules 2019 Mar 27;24(7). Epub 2019 Mar 27.

Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.

In this study, the influence of stevia addition and sonication processing parameters on the phenolic content and profile as well as the steviol glycosides of strawberry juice-based samples was investigated. For this purpose, three matrices-control samples of strawberry juices without green stevia powder (CS), strawberry juices with green stevia powder (JGSP), and sonicated juices with green stevia powder (SJGSP)-were prepared. For sonication purposes, different conditions regarding probe diameters (7 mm and 22 mm), amplitudes (50%, 75%, and 100%), and time (15 min, 20 min, and 25 min) were tested. The results that were obtained upon the measurement of the total phenolic content, total flavonoids, steviol glycosides, and antioxidant capacity showed significant differences according to the matrices evaluated, obtaining overall higher values in the samples with stevia added. Moreover, when sonication was evaluated, it was found that a higher amplitude (100%), a larger probe diameter (22 mm), and a longer sonication period (25 min) led to higher values. Flavones such as luteolin and apigenin were identified and quantified in JGSP and SJGSP, while they were not found in CS. Besides these phenolic compounds, kaempferol, quercetin, pyrogallic acid, 4-methylcatechol, and 4-methoxybenzoic acid were also identified and quantified. Similarly to the total phenolic compounds, total flavonoids, and total antioxidant capacity, an increased amount of these compounds was found in SJGSP, especially after using the most intense sonication conditions. Therefore, the use of sonication together with stevia added could be a useful tool to preserve strawberry juices, increasing at the same time the sweetness and the antioxidant value of the beverages.
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http://dx.doi.org/10.3390/molecules24071202DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6479960PMC
March 2019

Antioxidant Potential of Fruit Juice with Added Chokeberry Powder (Aronia melanocarpa).

Molecules 2017 Dec 5;22(12). Epub 2017 Dec 5.

Department of Agricultural Technology, Storage and Transport, Faculty of Agriculture, University of Zagreb, Svetošimunska Cesta 25, 10 000 Zagreb, Croatia.

The purpose of this study was to determine the possibility of using chokeberry powder as a supplement in apple juice to increase the nutritional value of the final product with the aim of developing a new functional food product. Also, to determine the influence of ultrasound assisted extraction on the bioactive compounds content, nutritional composition and antioxidant potential of apple juice with added chokeberry powder. The juice samples with added chokeberry powder had higher antioxidant capacity, irrespective of the extraction technique used. Apple juice samples with added chokeberry powder treated with high intensity ultrasound had significantly higher content of all analyzed bioactive compounds. The application of high intensity ultrasound significantly reduced the extraction time of the plant material. A positive correlation between vitamin C content, total phenols, flavonoids and anthocyanins content and antioxidant capacity was determined in juice samples with added chokeberry powder treated with high intensity ultrasound.
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http://dx.doi.org/10.3390/molecules22122158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6149817PMC
December 2017

Variation in the bioactive compound content at three ripening stages of strawberry fruit.

Molecules 2014 Jul 17;19(7):10370-85. Epub 2014 Jul 17.

Department of Agricultural Technology, Storage and Transport, Faculty of Agriculture, University of Zagreb, Svetošimunska cesta 25, HR-10000 Zagreb, Croatia.

During the harvest season of two consecutive years, five strawberry cultivars ('Arosa', 'Elsanta', 'Marmolada', 'Miss' and 'Raurica'), grown in the continental part of the Republic of Croatia, were examined. Strawberry fruits quality was evaluated by individual phenol compounds, individual anthocyanins and fruit color. Fruits were harvested in three different periods. Analyzed strawberry cultivars show very good average values of the studied phenolic acids and flavonoids with predominant caffeic acid and epicatechin content in all researched strawberry cultivars. Considering the content of individual anthocyanins, pelargonidin 3-glucoside is predominant in strawberry extract followed by cyanidin-3-glucoside and pelargonidin 3-rutinoside. The correlation between individual anthocyanin content and chromaticity parameters was detected in all strawberry cultivars, additionally correlation coefficients and statistical significance were much lower. The results show a positive association between cultivar and harvest time on strawberry pulp color, with each of the color variables, a, b, a/b ratio, C, L and h° values.
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http://dx.doi.org/10.3390/molecules190710370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6271993PMC
July 2014

A comparison of fruit chemical characteristics of two wild grown Rubus species from different locations of Croatia.

Molecules 2012 Aug 30;17(9):10390-8. Epub 2012 Aug 30.

Faculty of Agriculture, University of Zagreb, Svetošimunska 25, 10000 Zagreb, Croatia.

The main focus of our study was to investigate differences in nutritional (dry matter, soluble solids content, total acidity and pH value) and bioactive values (ascorbic acid, total anthocyanins, total phenols, and non-flavonoids content) of wild grown raspberry (Rubus idaeus) and blackberry (Rubus discolor) genotypes harvested from native populations in Croatia. The average total acidity ranged from 0.93 to 1.72% in R. discolor and 1.57 to 1.91% in R. idaeus. Ascorbic acid was found between 22.34 mg and 45.00 mg 100 g⁻¹ in R. idaeus, while it was between 30.64 mg and 33.09 mg 100 g⁻¹ in R. discolor genotypes. A great variability in total anthocyanins was detected in roatian wild blackberry and raspberry genotypes, ranging from 2,226 to 2,367 mg kg⁻¹ for blackberries and 279 to 582 mg kg⁻¹ for raspberries, indicating wild blackberries are particularly rich in anthocyanins. On the basis of these results, it can be concluded that investigated wild growing fruit species have a great potential in nutritive research, as well as in biodiversity research. It is necessary to carry out further investigation and evaluation of wild growing fruit species to utilize them in the most appropriate way, as well as conservation of interesting accessions in the gene banks.
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http://dx.doi.org/10.3390/molecules170910390DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6268757PMC
August 2012

The change of fruit quality parameters in day-neutral strawberries cv. Diamante grown out of season.

Int J Food Sci Nutr 2009 May 3;60(3):248-54. Epub 2008 Nov 3.

Department of Agricultural Technology, Storage and Transport, Faculty of Agriculture, University of Zagreb, Svetosimunska 25, Zagreb, Croatia.

This research was conducted on the strawberry cultivar Diamante in continental parts of Croatia. The experiment was designed as four replicates with 100 plants for each harvest time. The quality of strawberries cv. Diamante grown out of season (fruit were picked in the early morning hours at three harvest times: 27 June, 7 September, 28 October) was determined. Total soluble solids ( degrees Brix) ranged from 5.00% to 7.03%, total acidity ranged from 1.05% to 1.12%, total soluble solids/acidity ranged from 4.74 to 6.34, vitamin C ranged from 40.73 mg/100 g fresh weight to 46.68 mg/100 g fresh weight, pH ranged from 3.53 to 3.72, total phenols ranged from 276.48 to 326.76 mg/l, non-flavonoids ranged from 169.50 to 260.53 mg/l, and flavonoids ranged from 44.71 to 106.53 mg/l, respectively. In addition, total anthocyanins ranged from 15.95 to 21.70 mg/l. The lightness L values of fruits ranged from 30.24 to 41.05, chroma C values from 25.92 to 34.13, and Hue angle H values from 44.51 to 56.02. The data showed that cv. Diamante grown out of season is of satisfactory quality.
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http://dx.doi.org/10.1080/09637480701706331DOI Listing
May 2009