Olivera Đuragić

Quality control of full-fat soybean using urease activity: Critical assessment of the method

A critical assessment of the method for determination of urease activity, as an indicator of the degree of full-fat soybean (FFSB) processing, has been undertaken. FFSB was processed by dry extrusion at five temperatures, ranging from 115oC to 165oC, and analyzed for urease activity by two laboratories and by two analysts at each laboratory, using the pH-difference procedure. The in vivo trial with chickens fed the processed FFSB has also been conducted. While the results of two analysts at each laboratory did not differ significantly (P>0.05), there was a significant difference (P<0.05) in urease activity results between the two laboratories. The overall conclusion of this study is that the urease activity determined by pH-difference method can not be recommended as a reliable indicator for FFSB quality control.

Fatty Acid Composition and β-Carotene Content in Egg Yolk of Laying Hens Fed with Linseed, Paprika and Marigold

Summary Eggs enriched with n-3 fatty acids and natural pigments are desirable in human food chain due to numerous benefits for health. In this study, we investigated the effects of inclusion of co-extruded linseed and sunflower meal into laying hens’ diet and replacement of synthesized pigment with paprika and marigold flower as sources of natural pigments. Four hundred 18–wk-old Bovan laying hens divided in two groups (control and experiment) were fed for 12 weeks. Fatty acids and β-carotene were monitored every fourth week and successively analyzed. Significantly (p<0.05) increased content of α-linolenic acid in egg yolk in the experimental group in comparison to the control group was observed with addition of linseed, paprika and marigold in laying hens’ nutrition. Nearly the same tendency was observed in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content. Supplementation of the co-extruded linseed and sunflower meal into laying hens’ diet demonstrated significantly (p<0.05) lower n-6/n-3 FA ratio in experimental group compared to control group. The obtained results showed that the synthetic pigment added to laying hens’ diet provided better pigmentation of egg yolks after one and two months of the feeding trial than paprika and marigold flower. The concentration of β-carotene in egg yolks increased in experimental group after three months of the treatment, and that was the first time that concentrations of β-carotene did not significantly (p < 0.05) differ among control and experimental group, which shows that paprika and marigold flower as sources of natural pigments can successfully replace synthetic pigment. We shall continue research in this field with other supplemented mixtures, as there are indices for other potential feed enhancements among oily seeds and herbs.

Aflatoxins in maize harvested in the Republic of Serbia over the period 2012–2016

ABSTRACT Aflatoxins (AFs) are one of the most frequent contaminants in maize. The Republic of Serbia represents a leader in terms of maize production and exports in Europe. In recent years, Serbia faced climate changes. Therefore, the main objective of this study was to examine AF occurrence in 3000 maize samples collected during 2012–2016. In maize samples from 2012, 2013, 2015, and 2016, AFs were detected in 72.3%, 24.7%, 36.7%, and 5.0% of the samples, in concentration ranges of 1.0–111.2, 1.2–65.2, 1.1–76.2, and 1.3–6.9 µg kg−1, respectively. Contrary to this, in maize samples from 2014, no AFs were detected. Analysis of weather conditions indicates that 2012 was characterised by extreme drought conditions, 2013 and 2015 by lack of precipitation and high air temperatures, 2014 as the rainiest year in these years, while 2016 had moderate weather conditions.