Željko Jakopović

Dr. Željko Jakopović

orcid

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 December 2018 in Archives of Industrial Hygiene and Toxicology
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ŽKŽeljka Kuharić
Željka Kuharić
ŽJŽeljko Jakopović
Željko Jakopović
IČIva Čanak
Iva Čanak
JFJadranka Frece
Jadranka Frece
JBJasna Bošnir
Jasna Bošnir
KMKsenija Markov
Ksenija Markov
In order to minimise human exposure to aflatoxin M 1 (AFM 1 ) the levels of this highly carcinogenic mycotoxin in milk, heat-treated milk, and other dairy products have been limited to <0.05 μg kg -1 . However, its removal from dairy products presents a challenge for dairy producers, as commercial additives change organoleptic properties, and filtration alone yields poor results. The aim of this study was to find a strain of lactic acid bacteria (LAB) from milk or dairy products that most effectively binds AFM1 and to see whether heat treatment of the selected LAB affects the binding efficiency. We also wanted to investigate whether centrifugation can improve filtering of the obtained AFM1-LAB complexes from milk. To do that, we isolated and identified 10 native LAB species/strains, incubated their viable or heat-treated cells (10 8 CFU mL -1 ) in milk spiked with 0.5 μg L -1 of AFM 1 at 4 °C for 0, 2, 4, and 24 h, and quantified the amount of unbound AFM 1 with HPLC. AFM 1 binding efficiency ranged from 21 to 92 % for viable cells and from 26 to 94 % for the heattreated ones. Since both viable and heat-treated Lactobacillus plantarum KM showed the best results, we used it for the next step in AFM1 removal from milk. Heat treatment in combination with filtration and centrifugation yielded removal as high as 96 %.

1 January 2018 in Food Technology and Biotechnology
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Journal Article
Open access
ŽJŽeljko Jakopović
Željko Jakopović
KČKarla Hanousek Čiča
Karla Hanousek Čiča
JMJasna Mrvčić
Jasna Mrvčić
IPIrina Pucić
Irina Pucić
ICIva Canak
Iva Canak
KMKsenija Markov
Ksenija Markov
In this paper the effect of aflatoxin B1, ochratoxin A and zearalenon on morphology, growth parameters and metabolic activity of yeasts Saccharomyces cerevisiae, Saccharomyces uvarum, Candida utilis and Kluyveromyces marxianus was determined. The results showed that the three mycotoxins affected the morphology of all these yeasts, primarily the cell diameter, but not their final cell count. Fourier transform infrared spectroscopy showed that the yeast membranes bound the mycotoxins, C. utilis in particular. The cell membranes of most yeasts underwent denaturation, except S. uvarum exposed to ochratoxin A and zearalenone. In the early stage of fermentation, all mycotoxin-exposed yeasts had lower metabolic activity and biomass growth than controls, but fermentation products and biomass concentrations reached the control levels by the end of the fermentation, except for C. utilis exposed to 20 µg/mL of zearalenone. The adaptive response to mycotoxins suggests that certain yeasts could be used to control mycotoxin concentrations in the production of fermented food and beverages.

23 September 2023 in Antioxidants
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Giorgio GrilloGiorgio Grillo
Giorgio Grillo
GCGiorgio Capaldi
Giorgio Capaldi
KRKristina Radošević
Kristina Radošević
ŽJŽeljko Jakopović
Željko Jakopović
KMKsenija Markov
Ksenija Markov
Giancarlo CravottoGiancarlo Cravotto
Giancarlo Cravotto
Pomegranate (Punica granatum L.) is well known for its high content of bioactives, including polyphenols, flavonoids, and tannins, which have been shown to exhibit a wide range of biological activities, such as antioxidant, antimicrobial, and anticancer effects. It is worth noting that the majority of these molecules are found in the peels, which are usually disposed of after processing, causing a significant amount of waste, amounting to more than 3.6 million t/y. This work investigates microwave-assisted extraction (MAE) in water for the recovery of antioxidants from pomegranate peels (PP), including the optimisation of temperature and extraction times. The total phenolic, anthocyanin, flavonoid, and tannin contents of the recovered extracts were determined, as well as their antioxidant activities, which were found to be 356.35 mgGAE/gExtr, 303.97 µgCy3G/gExtr, 37.28 mgQE/gExtr, 56.48 mgGAE/gExtr, and 5.72 mmolTE/gExtr, respectively (according to the adopted reference). All results were compared with those obtained using a conventional protocol. In addition, the potential for water recycling by means of downstream nanofiltration in optimised MAE was investigated, leading to overall water reuse of approx. 75%. Power consumption (20.92 W/mgGAE) and common green metrics, Reaction Mass Efficiency (RME), E-Factor, and the Process Mass Intensiti/efficiency (PMI, PME), were considered in evaluating the proposed PP valorisation strategy. Finally, the biological activities of the main products were assessed. The antimicrobial properties of the PP extracts against three Gram-positive and three Gram-negative bacteria and their antiproliferative activity towards human cancer cells were tested. S. aureus bacteria was the most susceptible to the PP extracts. All tested products displayed antiproliferative activity against HeLa cells when higher concentrations were tested, with D-PP/NF (obtained from dried PP and sequential nanofiltration) being the most effective. This result was also confirmed via clonogenic analysis, which generally indicated the possible anti-cancer activity of pomegranate peel extracts obtained using this green approach.

12 November 2021 in Toxins
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TLTina Lešić
Tina Lešić
Manuela ZadravecManuela Zadravec
Manuela Zadravec
Nevijo ZdolecNevijo Zdolec
Nevijo Zdolec
Ana VulicAna Vulic
Ana Vulic
IPIrena Perković
Irena Perković
Jelka PleadinJelka Pleadin
Jelka Pleadin
The aim of this study was to identify and compare surface mycobiota of traditional and industrial Croatian dry-fermented sausage Kulen, especially toxicogenic species, and to detect contamination with mycotoxins recognized as the most important for meat products. Identification of mould species was performed by sequence analysis of beta- tubulin and calmodulin gene, while the determination of mycotoxins aflatoxin B1 (AFB1), ochratoxin A (OTA), and cyclopiazonic acid (CPA) was carried out using the LC-MS/MS (liquid chromatography-tandem mass spectrometry) method. The results showed a significantly higher number of mould isolates and greater species (including of those mycotoxigenic) diversity in traditional Kulen samples in comparison with the industrial ones. P. commune, as a potential CPA-producer, was the most represented in traditional Kulen (19.0%), followed by P. solitum (16.6%), which was the most represented in industrial Kulen samples (23.8%). The results also showed that 69% of the traditional sausage samples were contaminated with either CPA or OTA in concentrations of up to 13.35 µg/kg and 6.95 µg/kg, respectively, while in the industrial samples only OTA was detected (in a single sample in the concentration of 0.42 µg/kg). Mycotoxin AFB1 and its producers were not detected in any of the analysed samples (<LOD).

1 January 2018 in Food Technology and Biotechnology
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Journal Article
Open access
ICIva Canak
Iva Canak
KMKsenija Markov
Ksenija Markov
EMEna Melvan
Ena Melvan
ASAntonio Starcevic
Antonio Starcevic
MŽMattea Živković
Mattea Živković
JFJadranka Frece
Jadranka Frece
Lactobacillus plantarum O1 was isolated from the gut of sea bream (Sparus aurata) and identified with the API biochemical test and MALDI-TOF MS. This strain was further characterised according to the selection criteria for lactic acid bacteria as starter cultures for aquatic food production. L. plantarum O1 showed good antimicrobial activity against pathogenic test microorganisms. Further investigation confirmed it as the producer of the bacteriocin plantaricin. This strain also showed good growth at a wide range of temperatures (from 4 to 45 °C) and a wide range of pH (2-12), even in the presence of 3.5% NaCl. Its viability was also good after lyophilisation and in simulated gastric and small intestinal juice. The strain is a promising probiotic, and our further research will focus on its application in the biopreservation of fresh fish and shellfish.

17 June 2024 in Toxins
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Journal Article
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SZSlaven Zjalic
Slaven Zjalic
KMKsenija Markov
Ksenija Markov
JLJelena Loncar
Jelena Loncar
ŽJŽeljko Jakopović
Željko Jakopović
MBMarzia Beccaccioli
Marzia Beccaccioli
Massimo ReverberiMassimo Reverberi
Massimo Reverberi
Viticulture has been an important economic sector for centuries. In recent decades, global wine production has fluctuated between 250 and almost 300 million hectoliters, and in 2022, the value of wine exports reached EUR 37.6 billion. Climate change and the associated higher temperatures could favor the occurrence of ochratoxin A (OTA) in wine. OTA is a mycotoxin produced by some species of the genera Aspergillus and Penicillium and has nephrotoxic, immunotoxic, teratogenic, hepatotoxic, and carcinogenic effects on animals and humans. The presence of this toxin in wine is related to the type of wine—red wines are more frequently contaminated with OTA—and the geographical location of the vineyard. In Europe, the lower the latitude, the greater the risk of OTA contamination in wine. However, climate change could increase the risk of OTA contamination in wine in other regions. Due to their toxic effects, the development of effective and environmentally friendly methods to prevent, decontaminate, and degrade OTA is essential. This review summarises the available research on biological aspects of OTA prevention, removal, and degradation.