PL
Celami badań były oznaczenie frakcji żywieniowych skrobi oraz ocena wartości wskaźnika trawienia skrobi zawartej w ziemniakach odmiany Lord, surowych i poddanych powszechnie stosowanym metodom obróbki kulinarnej. Materiał badawczy stanowiły ziemniaki, które poddano gotowaniu, odgrzewaniu w mikrofalówce oraz smażeniu. Zawartość skrobi całkowitej nie uległa istotnym zmianom na skutek zastosowanych technik kulinarnych (p > 0,05) i wynosiła średnio 11,8 g·100 g⁻¹. Wykazano natomiast, że smażone ziemniaki charakteryzowały się większą zawartością skrobi opornej (1,2 g·100 g⁻¹) i powoli trawionej (1,0 g·100 g⁻¹), w porównaniu do ziemniaków przygotowanych innymi technikami kulinarnymi. Odgrzewanie na drugi dzień ugotowanych ziemniaków w mikrofalówce również w istotny sposób wpływało na tworzenie się skrobi opornej (1,1 g·100 g⁻¹). Wykazano jednak, że zarówno gotowane, smażone, jak i odgrzewane ziemniaki zawierały dużą ilość skrobi szybko trawionej i tym samym miały wysokie wartości wskaźnika trawienia skrobi (81–92%).
EN
The aim of this study was to determine the content of starch nutritional fractions and the rate of starch digestion index of Lord variety potatoes raw and processed in the course of common culinary processing. Material consisted of potatoes subjected to boiling, reheatnig in the microwave and frying. The content of dry matter [AOAC 2006] was determined in the tested material, as well as the free glucose (FG) and the glucose hydrolyzed glucose after 20 (G20) and 120 minutes (G120) digestion according to the method of Englyst et al. [1992] modified by Chung et al. [2010] with the following enzyme solutions: α-amylase from porcine pancreas (P-7545, Sigma-Aldrich, St. Louis, Mo, USA), amyloglucosidase (3300 U · ml⁻¹, Megazyme Int. Ireland Ltd., Bray, Ireland) and invertase (I-4504, 300 U · mg⁻¹, Sigma-Aldrich). The level of the released glucose was determined by a colorimetric method using a reagent containing the enzymes: glucose oxidase and peroxidase (K-GLOX, Megazyme). Resistant starch (RS) and the total starch (TS) was determined by AOAC Method 2002.2; AACC 32-40 (K-RSTAR, Megazyme). Based on the above results, the following parameters were calculated: rapidly digestible starch (RDS) = (G20-FG) · 0.9, slowly digestible starch (SDS) = (G120 – G20) · 0.9 and starch digestion index (SDI) [%] = (RDS · TS-1) · 100. Starch fraction measurements were performed in three parallel repetitions. Total starch content did not change as a result of the applied culinary processing (p>0.05) and was on the approx. level of 11.8 g·100 g⁻¹. The fried potatoes were characterized by a higher content of RS (1.2 g·100 g⁻¹), and SDS (1.0 g·100 g⁻¹), compared with potatoes prepared by other techniques. Reheating of potatoes on the second day after boiling in a microwave oven had also a significant effect on the formation of RS (1.1 g·100 g⁻¹). It has been shown, that either boiled, fried or reheated potatoes contained a large quantity of RDS and thus had high values of the SDI (81–92%). The applied processes resulted in the expected significant increase in the content of RDS in the potatoes of Lord variety. At the same time, the processes of frying and reheating after cooking of the potatoes contributed to a significant increase in the SDS and RS fractions, as compared to the cooking process. Lord potato varieties were characterized by high values of SDI, regardless of the method of culinary preparation, which may indicate a high glycemic index values of the dishes prepared with this potato variety.