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A convenient way to obtain a compact, flawless coating with nano-order thickness is by forming thin self-assembled molecular layers (SAMs). Crosslinking of the SAMs hardens the coatings, reduces penetration of external molecules, improves mechanical strength and chemical resistance, as well as other functional properties making such coatings more resistant and significantly extending their lifetimes. Radiation crosslinking refers to the process where high energy radiation, gamma-rays or fast electrons are used to induce a chemical reaction that results in formation of a 3D network. If for self-assembling is performed with an environment friendly compound like a fatty acid the use of the obtained coatings would be non-toxic and completely safe for the person applying the coating, as well as the person handling the coated object. Irradiation conditions are crucial for obtaining crosslinked coatings, but also other parts of the process can influence the outcoming properties of the coatings. The aim of this study is to determine the influence of the conditions in which the SAMs are formed on copper on the properties of the radiation crosslinked films used for protection of copper in atmospheric conditions: the influence of the formation of an oxide layer on which the coatings are formed, on the conditions of the self-assembling process from an ethanol solution, and the influence of drying after self-assembling. All these steps are performed prior to gamma irradiation. Elaidic acid, C₁₈H₃₄O₂, a trans-fatty acid, is used for preparation of the coatings on copper and the obtained crosslinked coatings protective properties are studied in a solution simulating atmospheric conditions. The investigations are performed by electrochemical techniques and by Attenuated total reflectance surface-enhanced infrared spectroscopy, ATR-SEIRAS. We thank the Croatian Science Foundation (HRZZ IP- 2020-02- 4344) for supporting the research.

The aim of this study was to test gamma irradiation in reduction of aflatoxin B1 (AFB1) and ochratoxin A (OTA) toxicity. For this purpose, maize seeds samples contaminated with AFB1 (n=30) and dry-cured meat products contaminated with OTA (n=24) were investigated. Additionally, non-irradiated and gamma irradiated AFB1 and OTA standard solutions were tested for cytotoxicity and analyzed on LC-MS/MS. Gamma irradiation (5 and 10 kGy dose) reduced AFB1 level in maize seed samples for 35.1 to 98.6 %. In dry-cured meat samples gamma irradiation (up to 10 kGy dose) reduced OTA level for 17.70 to 33.66 %. Gamma irradiated AFB1 and OTA were less toxic to cells than non-irradiated mycotoxins, and resulted with reduced AFB1 and OTA level. In conclusion, gamma irradiation reduced AFB1 and OTA level in different commodities and their radiolytic products were less toxic, implying that gamma irradiation can be safely used for decontamination of mycotoxins in various feed and food.

A big part of our cultural heritage (CH) is made from natural materials which are very sensitive to surrounding conditions and thus get easily infected. Disinfection through ionizing radiation has been proven to be very effective, because it is based on electromagnetic radiation from radioactive 60Co, which causes chemical damage of DNA molecules of all biological pollutants, while on the other hand in most cases leaving the materials constituting the object intact. Contrary to all other methods gamma rays are highly penetrating acting on all pests present in the whole volume of a treated object in their whole life cycles ; from spores to grown pests. Among all the advantages of radiation technology it needs to be outlined that it is harmless for humans and damage of the material is minimal, when using optimal conditions. In the process of irradiating a CH object the most important parameter to pay special attention to is the irradiation dose. The used dose depends on the type and degree of contamination, the desired reduction of pests and their radio sensitivity, as well as type of material and its condition. It is necessary to apply the smallest possible dose for deactivation of biological contaminants, which should also be smaller than the dose that would induce any changes in the material or change its appearance. In this work, we investigated the influence of radiation on natural leather which is used for restoring leather book covers using gama rays. With this research, we wanted to investigate the effect ionizing radiation has on natural leather, treated and non-treated. The main objective was to determine can radiation technology be used for preservation of cultural heritage made of leather and in which conditions. Applying radiation to objects made of leather, such as clothing, book covers or furniture is still rare due to insufficient research into the effects of radiation on leather. This work investigates the effect of ionizing radiation on natural leather, unimpregnated and impregnated, in order to determine whether radiation technology can be used for protection and preservation of CH made from leather. Goatskin was used for the investigations with two types of common impregnation agents: Leather preservative and Talas SC600 preservative. The samples were tested by colorimetry and pH measurements, as well as FTIR. In the dose range used on cultural heritage at both investigated dose rates no observable changes were noticed, according to colorimetry, pH or FTIR.

Copper is a reddish-gold metal that is easily worked and drawn, it conducts both heat and electricity very well. Because of its very good properties it has a wide range of applications and is exposed to various often aggressive environments. Therefore, additional protection is required to enhance the protective properties of its naturally formed oxide film. Formation of a thin protective film on the copper surface is a good and practical way to enhance the metal’s natural protective properties. Fatty acids are non-toxic compounds which have an affinity for adsorbing on metals with their hydrophobic end, the carboxyl group. The other end of fatty acids, the methyl group, has hydrophobic properties and when adsorbed on the metal surface it makes the whole surface of the metal appear hydrophobic. Thus by blocking access for water to the surface the dissolution of the metal is disabled [2]. Elaidic acid is a monounsaturated fatty acid found in hydrogenated vegetable oils. Because of its specific shape that it has thanks to the trans form of the double bond its molecules are close-packed on the surface of copper making the coating very compact and water difficult to approach the surface.

Mycotoxins, secondary metabolites of moulds, due to their toxicity represent serious public health issue. The most toxic among mycotoxins are aflatoxin B1 (AFB1), ochratoxin A (OTA) and fumonisin B1 (FB1). Different strategies in preventing animal and human exposure to mycotoxins are developed and are in use, and some new are investigating. We tested effect of gamma (γ) irradiation, as simple and cheap physical method, on: a) growth of mycotoxin-producing moulds and on b) reduction of mycotoxins level. In experiments γ irradiation dose of 10 kGy was not exceeded, since it is established that γ irradiation in dose up to 10 kGy do not present toxicological hazard nor introduce any nutritional changes in γ irradiated-commodities. Experiments on aflatoxicigenic moulds (Aspergillus parasiticus, Aspergillus flavus, and Aspergillus niger) demonstrated that γ irradiation in the dose of 5 kGy prevent sporulation, germination and growth of tested moulds. In AFB1-artificially contaminated feed samples (corn seed, ground corn seed and feed samples), as well as in AFB1-naturally contaminated corn samples (n=30), γ irradiation effectively reduced AFB1 level ; 5 kGy dose reduced AB1 level for around 70 %, while 10 kGy dose for around 90 %. In dry-cured meat products (n=24) prepared from intentionally-contaminated raw materials of OTA-treated pigs, 3 kGy γ irradiation dose reduced OTA level for about 8.5 % and 10 kGy dose for about 22.5 %. These results indicate that low γ irradiation doses (up to 10 kGy) can eliminate aflatoxicigenic moulds’ contamination and reduce mycotoxins in various goods, but reduction of mycotoxin depend on type of sample e.g. on complexity of matrix. In conclusion γ irradiation can be used in preventing animal and human exposure to mycotoxins, or by eliminating mycotoxin-producing moulds, or by direct mycotoxins reduction, thus minimizing toxic effect of mycotoxins.

Ochratoxin A (OTA) is a mycotoxin which contaminate a variety of foodstuffs worldwide and may be present in meat and offal of farm animals or in the products of animal origin made of contaminated raw materials. In process of food preservation, gamma (γ) irradiation shown to be an effective technique of decontamination as destroy pathogenic and spoilage microorganisms as well as reduces some toxins such as mycotoxins. The aim of this study was to investigate the efficiency of gamma irradiation on OTA reduction in meat products (n=24) using three types of homemade fermented sausages and cured meat products (ham and ribs) as frequently consumed meat product in Croatia. Final meat products produced from contaminated raw materials of muscle/adipose tissue were irradiated using gamma rays at doses of 7 and 10 kGy as doses applicable in food industry. Concentrations of OTA in pre- and post-processed products were quantified using a validated immunoassay (ELISA) method and expressed on the product dry matter. Before irradiation determined OTA concentrations were in range from 6.33 to 33.33 μg/kg. Following the 7 kGy-irradiation, the overall mean OTA reduction equalled to 14.1%, while the irradiation with a 10 kGy-dose achieved the overall mean toxin reduction of 23.7%, and maximall reached of 34.7%. The obtained results indicate that γ irradiation could reduce the OTA levels in meat product intended for human consumption, thus minimizing the human exposure to this carcinogenic mycotoxin, but also that due to the achieved reduction applied decontamination method is of limited value.

Sensitivity of natural fibers to biological deteriorants is a serious problem in protecting textile heritage objects. Radiation treatment is a common method of pest control and decontamination. In processing of objects of cultural heritage doses are selected according to contamination - up to 0.5 kGy for disinsection, 4-10 kGy for fungi control and 5-20 kGy ensures microbiological decontamination. Along with many other cultural heritage objects, textile items mainly ethnological significance were treated in 60Co gamma radiation source Ruder Boskovic Institute in Zagreb, Croatia [2] and were efficiently disinsected by applying of radiation dose of less than 2 kGy . In order to meet the high standards of conservators possible effects of higher doses should be assesed. Tests were conducted onmodel samples of the most commonmaterials in heritage items - silk, flax cotton, and wool. To ensure that any of the radiation effects will be observed a high dose of D=120 kGy in contact with air was applied. A part of the samples were heat- or UV - aged before exposure to γ- irradiation. Changes were determined by thermal analysis: differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that even such a large doses caused almost no change in the materials based on protein fibers (silk, wool, while those based on cellulose (cotton, flax showed somewhat reduced thermal stability on irradiation. SEM images confirmed those observations. Despite the high dose changes due to radiation were comparable to or lesser than those caused artificial aging. Based on these results it can be concluded that the radiation treatment iof heritage textile materials will not cause damage if performed fat the doses needed for controlling fungi.

Various commodities predominantly crops can be contaminated with moulds that can lead to economic losses in agriculture and in food industry. More importantly, some moulds produce mycotoxins, their toxic secondary metabolites, indicating that mould except economic loss can represent threat to animal and human health. Oneof the most toxic mycotoxin is aflatoxin B1 (AFB1) with hepatotoxic, teratogenic, immunosuppressive and carcinogenic properties. Due to its toxicity International Agency for Research on Cancer (IARC) classified AFB1 in group 1 as carcinogenic to humans. Countries around the world have limited the maximal level of mycotoxins in different food and feed commodities and in EU maximal tolerable level of AFB1in cereals and cereal-based products is set to 2.0 μg/kg. The level of AFB1in various commodities depends on climatic conditions under which the crops are harvested, stored and processed and higher AFB1level can be expected with higher humidity and temperature that favourable mould growth. It is important to try to control growth of moulds that can produce AFB1, or at least to keep their growth and production of AFB1to minimum. It is known that gamma irradiation could be effective in inactivating the growth of moulds, thus reducing AFB1level in commoditiesindirectly. The aim of this study was to investigate if gamma irradiation can be use as a method for direct reduction of AFB1level in corn/feed samples intended for animal consumption. For this purpose two separated experiments were performed. In the first experiment corn seeds, ground corn seeds and feed samples were artificially contaminated with known AFB1concentration (50 or 100 μg/kg), that can be expected in nature. For the second experiments corn seeds samples (n=30) naturally contaminated with AFB1and intended for animal consumption were collected inEastern part of Croatia. In both experiments gamma irradiation at 5 and 10 kGy were tested. Results of first experiment showed that gamma irradiation of feed samples with added AFB1at dose of 5 kGy reduced AFB1level for around 65%, while at dose of 10 kGy AFB1level was reduced for around 85%. In naturally contaminated corn samples overall reduction of AFB1level after 5 kGy irradiation was 69.8% while the overall mean toxin reduction was 94.5% when 10 kGy was applied. Together, these results indicate that gamma irradiation can be used in reducing AFB1level in various commodities intended for animal and human consumption thus minimizing animal and human exposures to this carcinogenic mycotoxin.

Moulds belonging to Aspergillus genus, mainly A. flavus, A. niger and A. parasiticus, are among the most important representatives that cause spoilage of food and feed products. The growth of fungi in foods or feeds is inhibited with application of different technological processes and various chemical additives. One of technologies that could prevent the growth of mould is radiation technology that uses ionizing radiation. This effective technology is widely used in food processes to destroy pathogenic and spoilage microorganisms without compromising the safety, nutritional properties and sensory quality of the food.

During oxidative stress reactive oxygen species and peroxyl radicals of lipids can be scavenged by good hydrogen donors such as thiols, leading to interrupting the cascade of the lipid peroxidation process. Therefore thiols are considered to be effective protectors for the lipid degradation under oxidative conditions. On the other side, thiyl radicals generated from thiols by free radicals cause the isomerization of the double bonds, with the formation of geometrical lipid trans isomers.The general objective of this work was a comparative study of the behaviour of unsaturated fatty acid in the presence of thiols. Primary radicals were generated by γ -irradiation of a model lipid system containing linoleic acid (LiH), nonionic surfactant (Tween 20) and 2-mercaptoethanol at pH 5. After γ -irradiation of the model systems up to 400 Gy and in the presence of oxygen, high concentration of LiOOH (1 × 10– 4 mol dm-3) was determined, while the amount of trans LiH methyl ester simultaneously formed under the same conditions was very low (~ 10 %). However, in the absence of oxygen the effective inhibition of propagation of lipid peroxidation with subsequent increasing of the isomerization processes was observed. It was found that the amount of trans isomers increased with increasing of the irradiation dose. The effect of the dose rate on the lipid modification processes was also investigated.