Абдигалиева т. Б
жүктеу/скачать 1,65 Mb. Pdf көрінісі
|
- Бұл бет үшін навигация:
- The chemical composition of eggs
- Sample preparation of yolk and fatty acids (FA) determination
| M
ETHODS Egg production and morphometric parameters of eggs The intensity of an eggs production of laying hens was determined as a ratio of number egg laid in experimental period and expressed as a percentage and was monitored for 8 weeks. Morphometric parameters of eggs were investigated at 3 th , 6 th and 9 th week of the experiment. The eggs were weighed, average eggshell thickness was measured. The density was measured by hydrometer. Next, eggs were broken to assess albumen quality using an egg analyzer Sampling method and organoleptic analysis were performed according to GOST procedures (GOST 2009) The chemical composition of eggs The chemical composition of eggs was determined. The moisture by drying at 105°C, fat by Soxhlet (GOST 2009) and total protein by a modified method of Kjeldahl (GOST 2005, 2008) was determined. Ash by using a muffle furnace by heating at 550°C for eight hours was determined. Sample preparation of yolk and fatty acids (FA) determination The eggs were manually broken and separated into egg albumen and yolk. Yolk lipids were extracted using a standard procedure according to Folch et al. (1957) applying chloroform and methanol (2:1 v/v). The FA composition of a yolk lipid was determined by a saponification/methylation procedure (EN ISO 12966- 1:2014/AC:2015). To the extracted yolk lipids (100 mg), placed in a screw capped glass tube, 4 cm 3 of 2 M NaOH was added and heated on a heating block. After 10 min, 5 cm 3 boron trifluoride-methanol complex were added and samples still heated. Next, 3 cm 3 isooctane was added to the boiling mixture and heated 1 min. After removing the flask from the heat source, without allowing the flask to cool, 20 cm 3 NaCl solution was added. Then, 2 cm 3 of the upper isooctane layer was transferred into vial and small amount of anhydrous sodium sulfate was added. Chromatographic analysis was performed using an Hewlett-Packard-6890 gas chromatograph with a flame-ionization detector (FID) and Supelcowax 10 capillary column (100 m×0.25 mm). The conditions of separation: carrier gas-helium; flow rate-1.5 ml 78 min -1 ; detector temperature 250°C; column temperature 60°C increase of 5°C min -1 to 180°C. Methyl esters of acids were identified by retention times and compared with mixture of methyl esters of fatty acids (Supelco 37 Component FAME Mix, 10 mg ml -1 in methylene chloride (F OLCH et. al 1957). жүктеу/скачать 1,65 Mb. Достарыңызбен бөлісу:
|