Tanja Petrović

Protection of probiotic microorganisms by microencapsulation

Probiotic bacteria are used in the production of fermented dairy foods, pharmaceutical products and health supplements. They play an important role in promoting and maintaining human health. In order, to produce health benefits probiotic strains should be present in a viable form at a suitable level during the products shelf life until consumption and maintain high viability throughout the gastrointestinal tract. Despite the importance of these beneficial microorganisms many investigations have shown their poor viability and stability, especially for bifidobacteria in fermented products. The introduction of microencapsulation techniques for protection of probiotic strains has resulted in greatly enhanced viability of these microorganisms in food products as well as in the gastrointestinal tract. This paper gives an overview of available microencapsulation techniques and materials for probiotic protection and stabilization. Several methods of microencapsulation for probiotic bacteria, including extrusion, emulsification, drying (fluidized bed, spray, freeze) and spray coating techniques, are presented. The commonly used supporting materials like alginate, starch, chitosan, gelatin, waxes, biogums, and some others are also discussed.

Encapsulation Systems in the Food Industry

Encapsulation is a useful tool to improve the delivery of bioactive and living cells into foods. Encapsulation aims to preserve the stability of the active compounds during processing and storage and to prevent undesirable interactions with the food matrix. In addition, encapsulation may be used to immobilise cells or enzymes in food processing applications, such as fermentation processes and metabolite production processes.

Antibacterial activity of aromatic plants essential oils from Serbia against the Listeria monocytogenes

The purpose of this study was to examine the effectiveness of selected essential oils for the control of the growth and survival of pathogenic bacteria Listeria monocytogenes ATCC 19112 and Listeria monocytogenes ATCC 19115, which are of significant importance in food hygiene. Essential oils extracted from Salvia officinalis L., Rosmarinus officinalis L., Majorana hortensis Moench., Thymus vulgaris L., Carum carvi L., Pimpinella anisum L. and Coriandrum sativum L. were evaluated. Antibacterial activity was done by the disk diffusion method in the presence of pure essential oils and four suspensions in alcohol. The best results obtained with Thymus vulgaris and Majorana hortensis essential oils, which were acting microbicidaly on both observed strains of Listeria monocytogenes, even in the small concentration. Because some of the essential oils were highly inhibitory even in small quantities to selected pathogenic bacteria, they may provide alternatives to conventional antimicrobial additives in foods. .

Mold/aflatoxin contamination of honey bee collected pollen from different Serbian regions

Assessment of microbiological quality of bee collected pollen is very important, because of its use as a supplement in the human diet. In this study, 26 samples collected from different location in Serbia were tested for the presence of mold through mycologial analysis. The presence of aflatoxin B1, one of the most dangerous and the most widespread mycotoxin was also determined. It was established that 10 of the investigated samples were contaminated with some genera or species of mold, but all of the investigated samples were contaminated with aflatoxin B1. Considering that there is no unique and official procedure for mycological analysis of bee collected pollen, these findings suggest the need for their establishment. Mycological analysis should be followed by mycotoxicological analysis since the absence of mold does not confirm the absence of aflatoxin B1 in bee pollen.

Antibiotic Susceptibility of Probiotic Bacteria

Lactic acid bacteria (LAB) are a heterogeneous group of bacteria widely distributed in nature. These bacteria are found in gastrointestinal (GI) and urogenital tract of humans and animals; they are present on plant material, in milk and meat, and numerous fermented foods. Lactic acid bacteria have been associated with traditional dairy products, cereals, vegetable and meat fermented foods, due to their natural presence leading to spontaneous fermentation. They are also used as starter cultures in industrial food production, as well as in the production of probiotic products due to their potential health benefits to consumer. Milk and dairy products are the most examined food system for the delivery of probiotic bacteria to the human gut. The probiotic concept has progressed and is now in the focus of different research. Significant improvements have been made in selection and characterization of new cultures and their application in food production.

Fusarium infection and deoxynivalenol contamination in winter wheat

In this paper, the incidence of Fusarium-infected grain of winter wheat and the content of mycotoxin deoxynivalenol (DON) was studied in two Serbian cultivars Simonida and NS40S, both harvested in 2014. The level of Fusarium contamination of wheat grain was determined using phytopathological techniques based on the standard methodology while DON was detected by enzyme-linked immuno-sorbent assay (ELISA). The incidence of Fusarium-infected grain ranged from 12 to 19% for Simonida and NS40S, respectively. Fusarium graminearum, as well-known producer of DON mycotoxin, was identified among Fusarium species. In addition, Alternaria spp. was isolated in high percentage, with an average incidence of 53% (Simonida) to 63% (NS40S).The average content of DON ranged from 424 μg kg-1 to 1101 μg kg-1 for Simonida and NS40S cultivars, respectively. Statistically insignificant negative correlation (r = - 0.18) was determined between Fusariuminfected grain and DON in the cultivar Simonida and statistically insignificant positive correlation (r = 0.11) in the cultivar NS40S. The mean levels of DON in studied wheat samples of both tested cultivars were not higher than the maximum permitted limit (1250 μg kg-1) although the level of Fusarium-infected grain of both cultivars was relatively high. These results indicate that both wheat cultivars are susceptible to Fusarium infection and DON mycotoxin production in agro-ecological conditions of Serbia, but the cultivar NS40S being more susceptible compared to cultivar Simonida. In view of all stated above, regular health check of grains and developing strategies for integrated monitoring of incidence of Fusarium head blight are necessary preventive measures in protection of winter wheat. [Projekat Ministarstva nauke Republike SRbije, br. TR-31023, br. TR- 31053 i br. TR-46010]

Natural mycobiota and aflatoxin B1 presence in bee pollen collected in Serbia.

Total fungal count, incidence of fungi and aflatoxin B1 (AFB1) concentration were studied in 33 samples of bee pollen randomly collected from beekeepers in Serbia. The total number of fungi was determined by dilution method whereas AFB1 was detected using the Enzyme-Linked Immuno-Sorbent Assay (ELISA). The mycological estimation showed the presence of nine genera of fungi as followed: Acremonium, Alternaria, Aspergillus, Cladosporium, Epiccocum, Fusarium, Mucor, Penicillium and Rhizopus, with total number ranging from 1 x 103 to 1 x 105 CFU g-1. The results have shown the predominance of the fungi from the genera Aspergillus and Alternaria. Among Aspergillus species it was observed that the most frequent species was A. flavus with incidence of 27.27 %. Mycotoxin AFB1 was detected as 100% positive in all samples (100%) with an average concentration of 8.61 μg kg-1. The obtained results indicated that honey bee pollen must be strictly controlled during its manipulation in the harvesting and manufacturing. Therefore, the implementation of good manufacturing (beekeeping) practice to define procedures for honeybee products could be crucial to reduce the risk of possible contamination and provide natural and safety product without risk on the human health. [Projekat Ministarstva nauke Republike Srbije, br. 46008, br. 46009 i br. 46010]

Correction to: Bioaccumulation process and health risk assessment of toxic elements in tomato fruit grown under Zn nutrition treatment

The original version of this article unfortunately contained a mistake in the author group, affiliation and funding information sections as well as the omitted acknowledgment section.

Bioaccumulation process and health risk assessment of toxic elements in tomato fruit grown under Zn nutrition treatment

AbstractThe aim of this work was to determine elements composition and bioaccumulation process in ripe tomato fruits influenced by zinc feeding of plants which was applied in three different doses. Macro- and microelement content in growing soil, seeds, and fruits was determined by ICP-OES method. Health risk assessment was calculated according to the presence of some toxic elements. It was found that predominant macroelements were phosphorus, potassium, calcium, and magnesium followed by other ten determined elements. The presence of five potentially toxic elements (cadmium, chromium, lead, nickel, and strontium) in seed and fruits was detected. Bioaccumulation differences (especially in case of potassium) for some elements in seed and fruit were established. In both cases, calcium and lead were the only elements with antagonistic effect towards zinc feeding process. Health risk assessment has shown that acute risk is low for all toxic elements (according to acute hazard quotient (HQ) calculation) except for cadmium in fruit seed, where it can be characterized as moderate. Long-term hazard quotient calculation showed moderate risk in the case of lead (fruit skin and seed) and low values for other toxic elements. Since the most part of toxic elements was accumulated in tomato fruit skin and seed, peeling of fruits can significantly reduce health risk. Graphical abstractᅟ

Traditional and Emerging Technologies for Autochthonous Lactic Acid Bacteria Application

Autochthonous strains of lactic acid bacteria, isolated from traditional cheeses, may be used as starter cultures in order to standardize the quality of traditional cheeses and/or as potentially beneficial bacteria, allowing the creation of new functional products. In addition to their good technological and biochemical properties, probiotic strains have to meet the criteria that include the Generally Recognized as Safe status, stability and activity/survival in the gastrointestinal tract (GIT) conditions as well as the health effects tested in in vitro and in vivo conditions. Some lactobacilli isolated from traditional Serbian cheeses have shown great tolerance to low pH and high bile salts concentration indicating their potential probiotic ability. In order to preserve the desirable properties of probiotic bacteria, it is necessary to apply the appropriate techniques for their preparation and storage. Different encapsulation techniques such as extrusion, emulsion, drying and spray-coating technique are available in order to achieve better viability and target delivery to GIT. Autochthonous potential probiotic strains (Lactobacillus paracasei 08, Lactobacillus plantarum 564) survived well the spray-drying process indicating that this microencapsulation technique could be a cost-effective way in protection of these strains. Screening and incorporation of new autochthonous potentially probiotic strains in different cheeses provides an opportunity to improve the healthy status and quality of the final products with desirable properties, considering their positive influence on the flavor of cheeses, in particular, low-fat and low-salt cheeses, goat cheeses, etc.