Microbial and Physico-Chemical Characterization of Cold Smoked Sea Bass (Dicentrarchus labrax), a New Product of Fishery

The aim of this study was to investigate the microbial and physico-chemical characteristics of cold smoked sea bass (CSSB), a novel italian fish product. The microbiological analyses showed the presence of bacterial contamination from the raw material, the environment, and the production process. The microbial spoilage population was dominated by lactic acid bacteria (LAB) associated with Gram-negative fermenting bacteria, including Photobacterium phosphoreum and psychrotrophic Enterobacteriaceae. Brochotrix thermospacta and Aeromonas spp. were also present; in contrast, mould and yeast were not detected (<2 CFU/g). High levels (6-7 log CFU/g) of LAB and total bacteria count (TBC) were observed from day 45 of storage; however, their presence does not seem to have influenced the total volatile basic nitrogen (TVB-N), which always remained below 35 mg N/100 g. Consequently, the product is acceptable until day 60 of storage, considering that the malonaldehyde index (TBARS) was lower than 6.5 nmol/g. Pathogenic bacteria such as Salmonella spp. and Listeria monocytogenes were not detected. Currently, there is a growing demand for seafood due to its high quality and nutritional value. Cold smoked sea bass offers a source of macro- and micronutrients essential for the proper functioning of the human body. It is also rich in protein and omega-3 fatty acids. The WHO and FAO evaluated the benefits and risks and concluded that there is convincing evidence of health benefits from fish consumption, such as a reduction in the risk of heart failure and improved neurodevelopment in infants and young children when fish is consumed by the mother before and during pregnancy. The CSSB analysed in this study demonstrated to have health benefits due to long-chain omega-3 PUFAs and other nutrients, such as proteins, minerals, and vitamin D, which are sometimes difficult to obtain from other sources. The results show that CSSB has a high nutritional value and excellent microbial quality.

Aflatoxins in Maize from Serbia and Croatia: Implications of Climate Change

Aflatoxins (AFs) represent the most important mycotoxin group, whose presence in food and feed poses significant global health and economic issues. The occurrence of AFs in maize is a burning problem worldwide, mainly attributed to droughts. In recent years, Serbia and Croatia faced climate changes followed by a warming trend. Therefore, the main aim of this study was to estimate the influence of weather on AFs occurrence in maize from Serbia and Croatia in the 2018-2021 period. The results indicate that hot and dry weather witnessed in the year 2021 resulted in the highest prevalence of AFs in maize samples in both Serbia (84%) and Croatia (40%). In maize harvested in 2018-2020, AFs occurred in less than, or around, 10% of Serbian and 20% of Croatian samples. In order to conduct a comprehensive study on the implications of climate change for the occurrence of AFs in maize grown in these two countries, the results of available studies performed in the last thirteen years were searched for and discussed.

Mycobiota and Mycotoxin Contamination of Traditional and Industrial Dry-Fermented Sausage Kulen

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).

A Two-Year Occurrence of Fusarium T-2 and HT-2 Toxin in Croatian Cereals Relative of the Regional Weather

To investigate into the T-2 and HT-2 toxin occurrence, 240 samples of unprocessed cereals (maize, wheat, barley, and oats) were sampled from different fields located in three Croatian regions during 2017-2018. In all samples, sum concentrations of T-2/HT-2 toxin were determined using the ELISA method, while the LC-MS/MS was used as a confirmatory method for both mycotoxins in positive samples (>LOD) and the establishment of T-2 over HT-2 toxin ratios. The results showed oats to be the most contaminated cereal, with T-2/HT-2 toxins detected in 70.0% of samples, followed by barley (40.9%), maize (26.8%) and wheat (19.2%), with the mean T-2/HT-2 ratio ranging from 1:2.7 in maize to 1:4.4 in oats. Sum T-2/HT-2 concentrations in two maize samples were higher than the indicative level recommended by the European Commission, necessitating subsequent investigations into the conditions under which these poorly investigated mycotoxins are produced. Statistically significantly (p < 0.05) higher concentrations of T-2/HT-2 toxin were determined in oats throughout study regions as compared to those found in wheat, but not maize and barley, while the concentrations of these mycotoxins were related to the regional weather in Croatia.

Aflatoxins and ochratoxin A in dry-fermented sausages in Croatia, by LC-MS/MS

The aim of this study was to develop a highly-sensitive liquid chromatographic - tandem mass spectrometric (LC-MS/MS) method to investigate the presence of aflatoxins (AFB₁, AFB₂, AFG₁ and AFG₂) and ochratoxin A (OTA) in traditional homemade sausages (n = 88) collected from small family farms situated in different regions in Croatia. Aflatoxins were not detected (<LOD) in any of the analysed samples, whereas the percentage of OTA-positive homemade sausages was 14.8%, consisting of 1.1% Istrian sausages, 7.9% Slavonian sausages and 5.7% Kulenova Seka. In Slavonian sausages, the mean OTA concentration was 0.27 ± 0.09 μg/kg with a maximum of 0.38 μg/kg, while in Kulenova Seka the mean concentration was 0.26 ± 0.14 μg/kg, rising to a maximum of 0.48 μg/kg. Statistically significant differences (p = .243) in OTA concentrations across different types of homemade sausage and sampling regions were not determined.

The effect of thermal processing on the reduction of deoxynivalenol and zearalenone cereal content

Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) often contaminate cereals and cereal by-products. Certain thermal processing methods used in the food industry show promising results in terms of reduction of cereal contamination with mycotoxins. In order to establish the degree of DON and ZEN reduction in naturally contaminated cereals (maize, wheat and oat), this study investigated the effects of cooking, roasting and extrusion cooking, performed at different temperatures (100 – 220 °C) and for a different length of time (10 – 30 min) on these mycotoxins concentrations. Before and after the treatment, cereal samples were analysed for DON and ZEN concentrations using enzyme-linked immunosorbent assay (ELISA). In comparison to cooking, which achieved only a negligible mean mycotoxin reduction (of up to 8% for DON and 11% for ZEN), roasting and extrusion cooking resulted in a significantly more pronounced mycotoxin reduction (of up to 40% for DON &amp; 46% for ZEN and of up to 75% for DON &amp; 80% for ZEN, respectively) (p &lt; 0.05). The results show similar effects of thermal processing on all of the studied cereals (p &gt; 0.05), suggesting that extrusion cooking can be considered as an effective thermal method capable of reducing mycotoxin content in cereals.

Gluconobacter oxydans – potential biological agent for binding or biotransformation of mycotoxins

The potential application of viable and heat-treated cells of Gluconobacter oxydans for binding or degradation of aflatoxin B1 (AFB1), citrinin (CIT), ochratoxin A (OTA) and patulin (PAT) in liquid matrix was investigated. Experiments were conducted using uncontaminated and toxin-containing YPM (yeast-peptone-mannitol) medium and inoculated with a bacterium suspension of either viable or heat-treated cells (108 cfu/ml) and incubated at 28 °C for 24 h. The unbound AFB1 and OTA were quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS), whereas CIT and PAT were quantified by high performance liquid chromatography (HPLC). Obtained results suggest that G. oxydans is able to bind various mycotoxins by 26 to 94%. Viable cells showed the best binding ability towards OTA and PAT (80.8 and 93.8%, respectively), while heat-treated cells bound less than 50% of tested mycotoxins. Fourier transform infrared spectroscopy (FTIR) showed that partial removal of mycotoxins involves physical binding of the toxin to the proteins and polysaccharides constituting the bacterial cell wall. Since mycotoxins contain numerous functional groups that multiply the IR spectra upon binding to bacteria, the precision of FTIR monitoring of bacteria-mycotoxin interactions is limited.

Cytotoxicity of gamma irradiated aflatoxin B1 and ochratoxin A

Toxicity of gamma irradiated mycotoxins aflatoxin B₁ (AFB₁) and ochratoxin A (OTA) was investigated in vitro. AFB₁ and OTA stock solutions (50 mM, in methanol) were gamma irradiated (5 and 10 kGy) and non-irradiated and irradiated mycotoxins solutions were tested for cytotoxicity on Pk15, HepG2 and SH-SY5Y cell lines (MTT assay, 1-500 μM concentration range; 24 h exposure). Degradation of mycotoxin molecules was examined by liquid chromatography tandem mass spectrometry (HPLC-MS/MS). AFB₁ and OTA radiolytic products were less toxic than the parent mycotoxins to all of the tested cell lines. Gamma irradiation even at 5 kGy had effect on AFB₁ and OTA molecules however, this effect was dependent on chemical structure of mycotoxin. Since gamma irradiation at low dose reduced initial level of both mycotoxins, and gamma irradiated mycotoxins had lower toxicity in comparison to non-irradiated mycotoxins, it can be concluded that gamma irradiation could be used as decontamination method.

Natural incidence of zearalenone in Croatian pig feed, urine and meat in 2014

The aim of this study was to determine the levels of zearalenone (ZEN) in different feed materials and feedstuffs for pigs, as well as in pig urine and pig meat following contaminated feed consumption. In total, 253 feed material and feedstuff samples were collected from Croatian pig farms. The results revealed the presence of ZEN in significant concentrations, the maximal being found in maize (5522 µg/kg), wheat (3366 µg/kg) and pig fattening feed (1949 µg/kg). In farms in which high feed contamination and pig hyperestrogenism were observed, samples of pig urine (n=30) and meat (n=30) were retrieved as well. The mean ZEN concentrations in pig urine and pig meat were 206±20.6 µg/L and 0.62±0.14 µg/kg, respectively. Despite high contamination of feedstuffs responsible for farmed pigs' intoxication, ZEN levels determined in pig meat were shown to be of little significance for human safety.

Correlation of deoxynivalenol and fumonisin concentration determined in maize by ELISA methods

Maize (Zea mays) is one of the most common crops in Croatia that is often contaminated with mycotoxins. The enzyme linked immunosorbent assay (ELISA) method as a screening immunological method has become very popular in the determination of mycotoxins contamination of cereals, as it has many advantages such as a rapid and simple determination of their concentration. In this present study, 40 maize samples collected from animal feed factories were analyzed for the concentration of deoxynivalenol (DON) and fumonisin (FUM) using the validated ELISA method of two different kit manufacturers to investigate the correlation of the determined mycotoxins concentration. The correlation coefficients for the concentration of DON and FUM, obtained using different kit manufacturers, were r = 0.9698 and r = 0.9303, respectively, yielding a high correlation between the applied ELISA methods. Concerning the legislation, in one maize sample, the DON concentration higher than the maximum recommended value was determined (16.24 mg/kg), whereas the FUM concentration in all the analyzed samples, without exception, were in accordance with recommended values.

Determination of ochratoxin A in serum and urine of pigs

The objective of the study was to determine ochratoxin A (OTA) concentrations in serum and urine of pigs during 30-day OTA treatment. OTA was administered orally to the experimental group (n=5) at a dose of 0.78 mg per animal per day, whereas control animals (n=5) were left untreated. OTA concentrations were determined using a validated enzyme-linked immunosorbent assay (ELISA). Method validation resulted in mean recoveries of 93-101% for serum and 98-106% for urine, with acceptable mean inter- and intraday relative standard deviations (<8% for urine and <7% for serum). The ELISA method can be effectively used as a simple screening method to determine OTA exposure in pigs during fattening. The maximum mean OTA concentration in serum was recorded on day 22 (8.75±2.93 ng/ml) and in urine on day 20 (43.56±35.76 ng/ml), indicating significant differences in OTA concentrations between these two matrices.

Biochemical changes in pig serum after ochratoxin A exposure

The objective of this study was to investigate the effect of ochratoxin A (OTA) on serum biochemical parameters of pigs during subchronic treatment with 300 μg OTA/kg of feed for 30 days. OTA treatment resulted in significantly higher (p < 0.05) serum levels of creatinine, urea, potassium and alkaline phosphatase, and significantly lower levels of glucose and total protein. These changes in serum biochemical parameters in treated pigs were indicative of impaired liver and kidney function caused by OTA exposure.

The natural occurrence of T-2 toxin and fumonisins in maize samples in Croatia

Maize (Zea mays) considered to be one of the most frequent crops in Croatia, is often contaminated with Fusarium mycotoxins. The aim of this study was to investigate the possible contamination of maize with T-2 toxin and fumonisins on 46 samples from different regions of Croatia. The highest concentrations of T-2 toxin and fumonisins were 210 and 25,200 ng/g, with mean values of 110 and 4,509 ng/g, respectively, pointing to maize contamination with these mycotoxins after the period of the year with extremely high rainfall.

Mould and mycotoxin contamination of pig feed in northwest Croatia

The aim of this study was to investigate the contamination of pig feed with moulds and the occurrence of mycotoxins. A total of 30 feed samples were collected at different animal feed factories in the north-western part of Croatia. Mycological analysis showed that the total number of moulds ranged from 1 × 10(3) to 1 × 10(5) cfu/g with samples contaminated with Aspergillus spp. (63 %), Penicillium spp. (80 %), and Fusarium spp. (77 %). A determination of aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON), T-2 toxin (T-2) and fumonisin (FUM) concentration was done using the validated ELISA method. The mean concentrations of AFB1 (0.5 ± 0.6 μg/kg), OTA (1.53 ± 0.42 μg/kg) and FUM (405 ± 298 μg/kg) were below the maximum levels or recommended values in the EU in all the investigated samples. The observed results indicated an increased contamination of pig feed with Fusarium mycotoxins DON and ZEA with mean concentrations of 817 ± 447 and 184 ± 214 μg/kg, higher than recommended in 40 and 17 % of the analysed samples, respectively.

Determination of T-2 and HT-2 toxins in commodities and feed in Croatia

Data on the occurrence of T-2 and HT-2 toxins in commodities and feed in Croatia and in Europe are very limited. In the present study, 50 feed and commodity samples tested for the presence of these mycotoxins yielded highest concentrations in cattle feed (67.68 ng/g) and oat samples (32.94 ng/g). In the future, screening should include greater numbers of feed and commodity samples to shed more light on the presence of T-2 and HT-2 toxins.