Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 5

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: herbata granulowana

Sortuj według:

Ogranicz wyniki do:

Determination of total contents of transition metals in selected granular black teas marketed in Poland

100%

Sykuła A. , Brodowska K. , Więdłocha M.

Biotechnology and Food Science

2014

tom Vol. 78, nr 1

45--52

The total contents of metals in three granulated black tea samples marketed in Poland were determined. Four elements consisting transition metals (Ni, Cu, Zn and Fe) were analyzed using flame atomic absorption spectrophotometry (FAAS). All examined tea brands contain considerable contents of the studied transition metals. Among the tested transition metals Fe (242-589 mg kg-1) was the most abundant one in the granular black tea imported from India. The highest value of Fe was analyzed in the cheapest tea, the smallest in the most expensive. The other metals are less abundant than Fe, their values varied from 8.50-8.90 for Ni, 7.80-10.4 for Cu and 8.13-12.6 for Zn mg kg-1. The accuracy of the proposed method was assessed by determining the recovery of metals from analyzed tea samples using the standard addition method. Recovery assays of nickel, copper, zinc and iron were demonstrated satisfactory, mean recoveries 99.29, 100.31, 99.94 and 99.79 %, respectively.

Badania zawartosci niektorych pierwiastkow sladowych w herbatach

51%

Bulinski R. , Bloniarz J.

Bromatologia i Chemia Toksykologiczna

1996

tom 29

nr 2

157-165

W dwudziestu rodzajach herbat (liściastych i granulowanych) oraz w naparach o średniej mocy sporządzonych z tych samych próbek herbat, oznaczono bezpośrednio z fazy wodnej zawartości: cynku, manganu, miedzi i żelaza. Analizę przeprowadzono metodą absorpcyjnej spektrometrii atomowej. Określono także stopień ekstrakcji tych mikroelementów do fazy wodnej.

Zinc, manganese, copper and iron content was determined in twenty grades of tea and tea infusions by atomic absorption spectroscopy using a Pye Unicam SP 192 apparatus. The following average concentrations were found in dry tea products: zinc - from 21.90 ppm to 57.80 ppm, degree of extraction (DE) from 27.3% to 56.0%; manganese - from 412.50 ppm to 1123.75 ppm, DE 20.5% to 51.9%; copper - from 20.50 ppm to 46.40 ppm, DE 10.8% to 28.3%; iron - from 116.50 ppm to 744.00 ppm, DE 2.5% to 10.1%. Overnormative amounts of copper in all tested tea samples may point to extensive use of copper fungicides in tea plantations. No evident differences were observed in trace elements content (except for iron) between the leafand granulated tea grades. The elements were not completely extracted to water phase during infusion, and the degree of extraction was not identical for all of them. Lowest extraction rate was observed for iron (about 10% maximum), followed by copper, manganese, and zinc (56% maximum).

Rynek kawy i herbaty

42%

Babicz M. , Ratajczak J.

Poradnik Handlowca. Branżowy Miesięcznik Ogólnopolski dla Sklepów i Hurtowni FMCG

2006

tom 13

nr 10

Badania zawartosci niektorych pierwiastkow sladowych w herbatach. Cz.II. Zawartosc olowiu, kadmu i niklu w herbatach i naparach herbacianych

42%

Bulinski R. , Bloniarz J.

Bromatologia i Chemia Toksykologiczna

1998

tom 31

nr 1

39-45

Metodą spektrometrii atomowo-absorpcyjnej oznaczono zawartość ołowiu, kadmu i niklu w dwudziestu rodzajach herbat (liściastych i granulowanych) oraz w naparach o średniej mocy sporządzonych z tych samych próbek. Dla ołowiu i niklu określono stopień ekstrakcji do fazy wodnej.

Lead, cadmium and nickel contents were determined in leaf and granulated tea and tea infusions by atomic absorption spectroscopy using a Pye Unicam SP 192 apparatus and air-acetylene flame. Various grades of tea were obtained from several retail shops and wholesale companies in Lublin during 1995. Grades of tea grown in India, China and Sri Lanka (Ceylon) were tested. Lead, cadmiun and nickel were assayed using extraction technique after the metals had been complexed with APDC (ammonium pyrrolidine dithiocarbamate). MIBK (4-methyl-2-pentanone) saturated with redistilled water was used as the organic phase. Values of lead content in dry leaf and granulated tea ranged on the average between 0.445 ppm to 1.615 ppm. From 30.1% to 60.0% dry-product total lead were extracted to medium-strong tea infusions. Average cadmium concentrations of the test tea grades were 0.012 ppm to 0.047 ppm. Trace amounts of cadmium were extracted to the tea infusions of medium strenght. Nickel content in dry tea was high, on average from 2.98 ppm to 9.29 ppm, and the degree of extraction to the water phase was 41.6% to 82.2%. Lead content of some leaf and granulated tea grades was higher than the admissible value specified by Polish regulations.

Rynek kawy i herbaty

34%

Turek K. , Ratajczak J.

Poradnik Handlowca. Branżowy Miesięcznik Ogólnopolski dla Sklepów i Hurtowni FMCG

2007

tom 14

nr 10

52-54