Food additives in chemistry lessons

Els additius alimentaris són components comuns en els aliments i un bon context d'estudi per a les classes de química. En aquest treball, es descriu una sessió de laboratori per a estudiants de secundària (17-18 anys). Els alumnes van determinar algunes propietats físiques i químiques de quatre additius «desconeguts». Utilitzant els resultats de les proves, els estudiants havien d'esbrinar, entre els deu possibles additius d'una determinada llista, quins eren els quatre additius analitzats. Els estudiants van treballar en petits grups. Un 26 % dels estudiants (grups) va identificar correctament els quatre additius, un 29 % en va identificar tres i el 45 % en va identificar dos.Food additives are common food components and they should be studied in chemistry classes. This paper describes a lab lesson for high school seniors (17-18 years old). They tested some physical and chemical properties of four unknown additives. Using the test results the students had to figure out which four of the ten additives from a list given had been tested. The students worked in small groups. All four correct additives were chosen by 26 % of students (groups), three correct additives by 29 % and two correct additives by 45 % of students

Validity of an FFQ assessing the vitamin D intake of young Serbian women living in a region without food fortification: the method of triads model

Objective: The objective of the present study was to examine the external validity of an FFQ designed to estimate dietary vitamin D intake compared with a plasma biomarker and three repeated 24 h dietary recalls in women of reproductive age in Serbia, where there is no exposure to food fortified with vitamin D. The method of triads was applied. Design: In a cross-sectional study, 422 women completed the Women and Reproductive Health FFQ (WRH-FFQ) during the winter months. From a representative subgroup (n 44), three 24 h dietary recalls and anthropometric parameters were collected as well as a fasting blood sample for vitamin D biomarker analyses. Correlation coefficients were calculated between each of the dietary methods. Validity coefficients, as a correlation between the measured and estimated 'true' exposure, were calculated using the method of triads. Bland-Altman plots were also constructed. Setting: Three major universities in Serbia. Subjects: Healthy young women (n 422) aged 18-35 years. Results: The WRH-FFQ estimate of vitamin D intake for all participants was 4.0 (SD 3.3) mu g/d and 3.1 (SD 2.3) mu g/d for the subgroup. Bland-Altman plots for these intakes showed high agreement. Validity coefficients for the FFQ, 24 h recall and biomarker were. rho(QI) = 0.847 (95 % CI 0.564, 0.928), rho(RI) = 0.810 (95 % CI 0.537, 0.997) and rho(BI) = 0.499 (95 % CI 0.190, 0.840), while the correlation coefficients were 0.686, 0.422 and 0.404. Conclusions: The FFQ applied in the present study is a valid tool for assessing dietary vitamin D intake in women living in Serbia, a region without mandatory vitamin D food fortification

Food additives in chemistry lessons

Els additius alimentaris són components comuns en els aliments i un bon context d'estudi per a les classes de química. En aquest treball, es descriu una sessió de laboratori per a estudiants de secundària (17-18 anys). Els alumnes van determinar algunes propietats físiques i químiques de quatre additius «desconeguts». Utilitzant els resultats de les proves, els estudiants havien d'esbrinar, entre els deu possibles additius d'una determinada llista, quins eren els quatre additius analitzats. Els estudiants van treballar en petits grups. Un 26 % dels estudiants (grups) va identificar correctament els quatre additius, un 29 % en va identificar tres i el 45 % en va identificar dos.Food additives are common food components and they should be studied in chemistry classes. This paper describes a lab lesson for high school seniors (17-18 years old). They tested some physical and chemical properties of four unknown additives. Using the test results the students had to figure out which four of the ten additives from a list given had been tested. The students worked in small groups. All four correct additives were chosen by 26 % of students (groups), three correct additives by 29 % and two correct additives by 45 % of students

Isolation and partial characterization of an acid phosphatase from Artemisia vulgaris pollen extract

An acid phosphatase from an extract of mugwort (Artemisia vulgaris) pollen was purified by a factor of 48 by a combination of ion exchange and gel-chromatography. The molecular weights of the enzyme were 76 kDa and 73 kDa, determined by gel filtration on a Sephadex G-100 sf column and by SDS PAGE (under reducing and non-reducing conditions), respectively. In analytical isoelectrofocusing, the enzyme appears as two very close bands, pI at about 4.2. The optimum pH for the enzyme is 5.4. The apparent Km for p-nitrophenyl phosphate was estimated to be 0.16 mM. The purified enzyme has broad specificity, and hydrolyses p-nitrophenyl phosphate and a-naphthyl phosphate. Pyrophosphate and O-phospho-L-tyrosine were estimated to be the best substrates for this enzyme as potential in vivo substrates. The enzyme is inhibited competitively by phosphate (Ki = 1.25 mM), molybdate (Ki = 0.055 mM) and pyrophosphate (Ki = 6.7 mM) and non-competitively by fluoride (Ki = 9.8 mM). Metal ions such as Hg2+, Cu2+ and Zn2+ express an inhibitory effect on the enzyme, while the enzyme is slightly activated by non-ionic detergents, Tween 20 and Triton X-100. There is no change in the enzyme activity in the presence of tartrate, citrate, EDTA, 1,10-phenanthroline and sulfhydryl-group modifiers such as p-chloromercuribenzoate and N-ethylmaleimide