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HPLC-ELSD determination of Phospholipids and Lysophospholipids in Grana Cheese samples at different ripening stages
No full textChanges in phospholipids (PL) and lysophospholipids (lysoPL) content were studied in Grana Cheese samples, with a ripening age ranging from 4 to 36 months. The extracted lipid fraction was purified by SPE and then analyzed by HPLC coupled to an evaporative light scattering detector (ELSD). The PL amount was lower than usually reported for milk fat. Variability of samples at the same ripening stage was high, because cheese was produced in different factories, but it decreased towards the end of ripening. A continuous increase in PL and lysoPL was observed during the first 12 months of ripening. The main PL class was phosphatidylcholine; other PL detected were phosphatidylethanolamine, sphingomyelin, phosphatidylinositol and phosphatidylglycerol. An increase of the lysophosphatidylcholine fraction was observed starting from the 12th month of ripening time, while the lysophosphatidylethanolamine content was related to the ripening stage
Metodi di analisi degli antiossidanti negli alimenti
No full textThe activity of natural antioxidants can be related to their concentration in food abd to factors (such as food composition, presence of synergic substances, temperature etc.)which contribute to the fibal antioxidat status in the food items, The classification of neutral components whit antioxidant properties is still poorly defined, since nutritional charateristics of several antioxidats (i,e, tocopherols, phospholipids, aminoacid-amines, etc,) are more important than their antioxidabt action. The analytical method for the evaluation of antioxidants should be considered toghether with the determination of antioxidant properties in dafined food, Methods for evaluation of tha amounts of antioxidants and the relative antioxidant power are reviewed
Cholesterol oxidation in commercial samples of "pandoro" cake during the shelf life/Ossidazione del colesterolo in Pandoro nel corso della conservazione
No full textThis paper presents the study of the oxidative pathway of cholesterol through the determination of the cholesterol oxidation products (COPs) during the conservation of "pandoro", a traditional Italian vanilla cake. The cholesterol content of this product is about 0.7% of total lipids which, on its turn, represent about 23% of the cake.
The determination of COPs was performed using gaschromatography after hydrolysis of the lipid extract, extraction of the unsaponifiable and purification with SPE. The identification of COPs was confirmed by means of GC-MS analysis.
The samples of pandoro contained small amounts of COPs at the starting time (between 2 and 3 ppm of the product). Their concentration did not increase during the shelf life of the product, neither in the sample which was analysed one month after its expiration date. However, different pathways were observed for each determined compound: the 7 alpha -hydroxycholesterol content showed a constant increase, whereas 7-ketocholesterol was characterized by a variable trend of concentration. Both the isomers of epoxycholesterol decreased. Starting from the third month of conservation the 5 alpha -cholesten-3,5,6-beta -triol rapidly increased. Based on this result, a possible conversion of epoxycholesterol to cholestantriol during conservation can be confirmed
Extraction and Purification of Free Cholesterol From Some Egg-containing Food by On-line SFE-SPE
No full textTwo methods for the extraction and determination of free cholesterol in some egg-containing food samples were compared: the classical Soxhlet method and a supercritical carbon dioxide extraction (at 338 bar and 40 degreesC) coupled on-line with solid-phase extraction (SPE with a solid trap packed with an ODS stationary phase). Egg noodles, biscuits and sweet snacks were homogenised and added to the internal standard and anhydrous sodium sulphate. Part of each sample was extracted by on-line supercritical fluid extraction - solid-phase extraction (SFE-SPE) and the remaining part was extracted by the classical method using petroleum ether. A further purification after the Soxhlet ex-traction was performed by SPE. Free cholesterol was determined in both the off-line Soxhlet-SPE fraction and the on-line SFE-SPE extract with capillary gas chromatography after silylation. The two extraction methods gave similar results. However, on-line SFE-SPE represents a Valid alternative to the Soxhlet method because it shows important advantages, such as a short analysis time and low solvent consumption
Estrazione con anidride carbonica supercritica dei prodotti di ossidazione del colesterolo
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Supercritical carbon dioxide extraction of phospholipids from dried egg yolk without organic modifier
No full textPhospholipids (PL) were successfully extracted from dried egg yolk by using neat supercritical carbon dioxide (SC-CO2) on a microscale. The spray-dried egg yolk powder was extracted with SC-CO2 at a density of 1.06 g/ml (517 bar, 40 degreesC), which was the maximum of density achievable with the apparatus. The extraction yield obtained by SC-CO2 (67 g of extract per 100 g of sample) can be compared with the conventional Bligh and Dyer extraction method (63 g of extract per 100 g of sample), which involves a chloroform/methanol/water mixture as an extraction solvent. The solvent extract contained 29% of PL, while the neat SC-CO2 extract consisted of 26% PL. HPLC analysis coupled with an evaporative light scattering detector (ELSD) showed no significant selectivity in the SC-CO2 extraction of the PL components. The extraction with neat SC-CO2 appears to be a valid alter-native for the extraction of PL for analytical purpose. (C) 2000 Elsevier Science B.V. All rights reserved
STUDIO GAS CROMATOGRAFICO PER LA CARATTERIZZAZIONE DEI SALAMI A DIVERSO GRADO DI MATURAZIONE
No full textSalamis are preserved meats requiring a period of agening so as to affect the chemical,phisical and microbiological alterations necessary to obtain the finished product. The capillary gas chromatographic analysis of organic extract of salami permits the study of evolution of lipids,glucides and other significative substances. This study is applied to several typical northern italian salamis differing as to recipe,size and type of additives employed. The resulting data, statistically processed to differenziates the salamis in relation to the factors tested, showed that the agening process is a highly discriminating factor.The analysis of variance also indicated that the types of additives and weight were not discriminating factors whereas the individual recipe pointed out a more complex overall picture
Determination of cholesterol oxidation products in the supercritical carbon dioxide extract of egg yolk powder: Comparison with conventional liquid solvent extraction methods
No full textNeat SC-CO(2) extraction was compared with the conventional Folch and the Bligh and Dyer (B&D) extraction, as a sample preparation technique for the determination of cholesterol oxidation products (COPS) in spray-dried egg yolk. Total lipids could be extracted in analytical scale (2 g sample) using four dynamic extraction steps of 30 min each, at 40 degreesC and 51,700 kPa. The recovery of total COPs in the SC-CO(2) extract (35 mug COPs g(-1) extract) was not statistically different with respect to the Folch and B&D extract. SC-CO(2) extraction showed important advantages, such as the elimination of chlorinated solvents and the reduction of sample manipulation and preparation time. The formation of artifacts of COPS due to the acidic properties of CO(2) during the sample preparation did not reach a significant extent
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