The subject of this study is the validation of a high-performance liquid chromatography method for the analysis of amino acids in feed. The contents of amino acids were determined in maize, soybean, soybean meal, as well as in their mixtures enriched with different amounts of methionine, threonine and lysine. The method involves the acid hydrolysis of the sample (6 h at 150ºC), automated derivatisation of amino acids with the aid of o-phthaldialdehyde and 9-fluorenylmethyl chloroformate reagents, separation on the ZORBAX Eclipse-AAA column, and detection using a diode-array detector. The method is characterized by high specificity (the difference between the retention times of the feed samples and standard mixtures are below 1.7 %), wide linear range (from 10 to 1000 nmol cm-3, r2 = 0.9999), high accuracy (recovery 93.3-109.4 %), and the precision of the results (RSD below 4.14 % in case of repeatability and below 4.57 % in the case of intermediate precision). The limit of detection and the limit of quantification are in the range 0.004-1.258 μg cm-3 and 0.011-5.272 μg cm-3, respectively. The results demonstrate that the procedure can be used as a method for the determination of the composition of primary amino acids of feed proteins. [Projekat Ministarstva nauke Republike Srbije, br. 31081

The color, aroma and fl avor are major sensory characteristics of honey, which are mainly determined by the botanical origin of honey as well as by processing and storage conditions. Increased moisture content above the maximum permitted level could result in honey spoilage, which aff ects its sensory properties. The higher water-in-honey content, the greater possibility of yeast fermentation and thus the change of the fl avor and color ofhoney. Fermentation process results in alcohol formation and, in the presence of oxygen, the alcohol will break down to acetic acid and water, which causes honey to have sour taste. Thus, moisture content of honey is a critical parameter for its quality as it aff ects the stability of honey and its resistance to microbial spoilage during storage. Physicochemical analysis of moisture content and acidity of honey play an important role in determining the overall characteristic of honey and final assessment of its quality. In this study, the investigation of aforementioned parameters resulted in positive quality assessment for 48 of 50 examined honey samples produced in 2013 in the territory of Vojvodina.

In this paper, the electrical conductivity and concentration of free acids (acidity) of various types of honey collected from the area of Vojvodina was investigated. Physicochemical analyzes of parameters such as electrical conductivity and acidity of honey have an important role in defining the overall properties of honey and assessing the quality of honey. A total of 55 samples of honey were examined. Out of the total number of samples, 5 samples did not meet the requirements of the Republic of Serbia Regulations on quality of honey due to inadequate electrical conductivity. Free acid values measured in tested samples ranged from 1.5 to 30 mEq / kg, and the values of electrical conductivity were in the range between 0.08 and 1.99 mS/cm. Our assumption that there is a correlation between the tested parameters has been confirmed only in meadow and polyfloral honey. Further research on the physicochemical properties of Serbian honey is recommended and important in order to establish certification marks and criteria for assessing the quality of Serbian honey.

2 Naučni institut za reprodukciju i v.o. domaćih životinja,Temerin, Srbija Izvod Ukupno je ispitano 14 različitih vrsta čajeva, i to: hajdučka trava, bosiljak, kantarion, pitoma nana, rastavić, kopriva, majkina dušica, kukuruzna svila, hibiskus, beli slez, kamilica, šipak-divlja ruža, vrijesak i divlja nana. Uzorci za merenje pripremljeni su metodom mikrotalasne digestije, a merenje je izvršeno sledećim metodama: masenom spektrometrijom sa indukovano spregnutom plazmom (Cd, Hg, Pb, As i Sb); atomskom apsorpcionom spektrometrijom (Mg); emisionom plamenom fotometrijom (Ca, K i Na) i spektrofotometrijom (P). Intervali varijacija (mg/kg) za makroelemente bili su: Ca (2738-35399); P (1545-6264); Mg (1647-7816); Na (293-10629) i K (9683-33985), a za toksične elemente: Cd (0,014-0,645); Hg (<0,001-0,017); Pb (0,064-1,340); As (0,030-0,544) i Sb (0,004-0,068). Treba istaći tri uzorka: hajdučka trava i dva uzorka kantariona u kojima je izmerena vrednost Cd (0,499± ±0,001; 0,539±0,002 i 0,645±0,003 mg/kg, redom) veća od 0,3 mg/kg, a koja predstavlja preporučeni dozvoljeni gornji nivo Cd u osušenom biljnom materijalu. Primenjena je Ward metoda hijerarhijske klaster analize, u cilju grupisanja biljnih čajeva po količini toksičnih elemenata.Ključne reči: biljni čajevi, makroelementi, toksični elementi, ICP-MS, AAS.

No abstract