Cross-Validation in Linear Discriminant Analysis of Triacylglycerol Structural Data from Istrian Olive Oils

This paper describes the differentiation and classification of olive oil samples produced in the Istrian peninsula in 3 areas characterized by different climatic conditions: Capodistria and Parenzo and Pola. The triacylglycerol (TAG) fraction of 41 samples of virgin olive oil was analyzed. In particular, TAG stereospecific analysis was performed to obtain the positional distribution of the fatty acids in the glycerol backbone. The quantitative data were evaluated by using Linear Discriminant Analysis, and the results obtained showed a differentiation of the olive oil samples according to their geographical origin. A cross-validation procedure, the Leave-One-Out classifier, was applied to test the adequacy of the discriminant model.

Italian Lycium barbarum L. Berry: Chemical Characterization and Nutraceutical Value

Lycium barbarum L. has received considerable attention in recent years also in western countries because of the interesting healthy value of these berries. In this paper, goji samples cultivated in Southern Italy were analyzed for their chemical composition and nutritional profile in order to characterize fruits of Italian origin and to increase the awareness about their nutraceutical value. Lipid fraction was characterized by high percentages of unsaturated fatty acids, in particular oleic and linoleic acids, and very low values of atherogenic and thrombogenic indexes (0.1 and 0.2, respectively). In addition, goji berry was an interesting source of phytosterols (41.5 mg/100 g), essentially represented by β-sitosterol. Carotenoid analysis showed the presence of zeaxanthin, in esterified form, with high content of zeaxanthin dipalmitate (277.9 mg/100 g). Finally, in vitro antioxidant capacity and phenolic compounds were investigated. The results suggested that goji hydro-alcoholic extract possessed the ability to scavenge free radicals. Phenolic acids were clearly the most abundant compounds followed by flavonols and favanols. The results reported in this study confirm that Italian L. barbarum berry is a rich source of bioactive molecules with nutraceutical properties.

Chemical and Nutritional Characterization of Seed Oil from Cucurbita maxima L. (var. Berrettina) Pumpkin

Pumpkin (Cucurbita spp.) has received considerable attention in recent years because of the nutritional and health-protective value of seed oil. The nutritional composition of pumpkin native to central Italy, locally known as “Berrettina” (Cucurbita maxima L.), was evaluated. In particular, the lipid fraction of seed oil was characterized, and the triacylglycerol (TAG) was thoroughly studied by using a stereospecific procedure to obtain the intrapositional fatty acid composition of the three sn-positions of the glycerol backbone of TAG. Moreover, alkaline hydrolysis was carried out to study the main components of the unsaponifiable fraction, i.e., sterols and alcohols. It was observed that monounsaturated fatty acids and polyunsaturated fatty acids were the most abundant (41.7% and 37.2%, respectively) in Berrettina pumpkin seed oil, with high content of oleic and linoleic acid (41.4% and 37.0%, respectively). The main sterols of Berrettina pumpkin seed oil were Δ^7,22,25-stigmastatrienol, Δ^7,25-stigmastadienol, and spinasterol; with regard to the alcoholic fraction, triterpenic compounds were more abundant than aliphatic compounds (63.2% vs. 36.8%). The obtained data are useful to evaluate pumpkin seed oil from a nutritional point of view. The oil obtained from the seed could be used as a preservative and as a functional ingredient in different areas, e.g., cosmetics, foods, and nutraceuticals.

Changes in extra-virgin olive oil added with Lycium barbarum L. carotenoids during frying: Chemical analyses and metabolomic approach

In this work, an Italian extra-virgin olive oil (EVOO) sample and the same sample added with a carotenoid-rich nutraceutical extract from Lycium barbarum L. (EVOOCar) were subjected to a frying process to comparatively assess chemical and physical changes and heat stability. Oxidation progress was monitored by measuring oil quality changes such as peroxide value, free acidity, K232, K268, and fatty acid composition as well as minor compound content, phenols, α-tocopherol, and carotenoids. An UHPLC/QTOF-MS metabolomics approach discriminated the two oil samples based on their chemical changes during frying, identifying also the phenolic classes most exposed to statistically significant variations. Partial least square discriminant analysis and volcano analysis were applied together to identify the most significant markers allowing group separation. The decrease in total phenolic content was lower in EVOOCar than in EVOO during frying. Monounsaturated and polyunsaturated fatty acids showed a significant percentage loss, 3.7% and 17.2%, respectively, in EVOO after 180min frying at 180°C, while they remained constant or slightly changed in EVOOCar. Zeaxanthin added to the oil rapidly decreased during the frying process. These findings showed that the addition of a carotenoid extract from L. barbarum can help to improve the oxidative stability of extra-virgin olive oil.

Composition of meat and offal from weaned and fattened rabbits and results of stereospecific analysis of triacylglycerols and phosphatidylcholines

BACKGROUND

Rabbit meat has excellent nutritive properties. The purpose of this study was to characterize rabbit meat and offal; in particular, the lipid fraction was studied in order to evaluate total and positional fatty acid (FA) compositions of triacylglycerol (TAG) and phosphatidylcholine (PC) fractions. Eight samples of weaned and eight of fattened rabbits were considered.

RESULTS

Fattened rabbit meat contained slightly higher protein percentage content (P < 0.05) in comparison to weaned (20.1% versus 18.0%). Calcium content was higher in meat than in offal, unlike sodium, iron, zinc, manganese and copper. The cholesterol content in offal was much higher than in meat. FA profiles of total lipid showed a high percentage of unsaturated fatty acids and an n-6/n-3 ratio of 10.3 for fattened rabbit meat. Stereospecific analysis of TAG and PC was carried out on an eight-sample pool of each meat and offal from weaned and fattened rabbits. In all samples the sn-2-position was prevalently esterified with oleic and linoleic acids in TAG, with polyunsaturated fatty acids in PC.

CONCLUSION

Lipids from rabbit meat presented higher content of monounsaturated FA and lower n-6/n-3 ratio in comparison to offal, which was characterized by higher cholesterol and mineral levels.

Improved HRGC separation of cis, trans CLA isomers as Diels-Alder adducts of alkyl esters

This paper reports the separation of four isomers of conjugated linoleic acid (CLA), c,t/t,c-8,10; c,t/t,c-9,11; c,t/t,c-10,12; c,t/t,c-11,13, after reaction of esterification with aliphatic alcohols of different chain length and adduct formation with 4-methyl-1,2,4-triazoline-3,5-dione (MTAD). The high resolution gas chromatographic analyses were carried out using a simple 50-m cyanopropyl polysiloxane capillary column both with a flame ionization detector and a mass spectrometer. The resolution between the two pair of isomers: c,t/t,c-9,11 and c,t/t,c-10,12 and between c,t/t,c-10,12 and c,t/t,c-11,13 isomers were good for all the investigated alkyl esters and increased with the chain length of alcohol esterified to carboxylic moiety of CLA isomers. The most interesting result was relative to the c,t/t,c-8,10 and c,t/t,c-9,11 isomers, critical pair of isomers also when analyzed with a 120-m cyanopropyl polysiloxane capillary column; their resolution also increased from methyl to hexyl esters of CLA isomers and reached an acceptable value (0.8) in the case of hexyl esters. The best resolutions of the four considered CLA isomers were obtained with the hexyl esters of MTAD adducts of the isomers, without excessive analysis time. This method was useful and simple to evaluate the profile of the four main c,t isomers in commercial CLA samples.

Original Normal-Phase High-Performance Liquid Chromatographic Separation of Monoacylglycerol Classes from Extra Virgin Olive Oil Triacylglycerols for Their Stereospecific Analysis

An innovative procedure to separate the 3 isomeric sn-monoacylglycerols (MAG) classes (sn-1-, sn-2-, sn-3-MAG) is described. MAGs, obtained by chemical deacylation of triacylglycerols (TAGs), have been derivatized with (S)-(+)-1-(1-naphtyl)- ethyl-isocyanate, and the resulting urethane derivatives have been separated by normal-phase high-performance liquid chromatography. This procedure allows resolution as diasteroisomers of the 2 enantiomeric classes (sn-1-MAG and sn-3-MAG), without the need of a chiral column, and to separate also the isomeric sn-2-MAG class; moreover, by introducing a chromophoric moiety, this reagent makes possible the ultraviolet detection of the analyte molecules. This procedure has been used to obtain the stereospecific analysis of the TAG fraction of extra virgin olive oil samples. The use of a nondestructive detector permitted the collection of the individual urethane classes; the fatty acid composition of each was determined by high-resolution gas chromatography, obtaining directly from the data the fatty acid distribution within each sn- position of TAGs. To validate this new method, the results have been compared with those obtained by 2 other procedures for TAG stereospecific analysis, and the obtained results were satisfactory since the proposed method gave data very similar to the other procedures.

Original normal-phase high-performance liquid chromatographic separation of monoacylglycerol classes from extra virgin olive oil triacylglycerols for their stereospecific analysis

An innovative procedure to separate the 3 isomeric sn-monoacylglycerols (MAG) classes (sn-1-, sn-2-, sn-3-MAG) is described. MAGs, obtained by chemical deacylation of triacylglycerols (TAGs), have been derivatized with (S)-(+)-1-(1-naphtyl)ethyl-isocyanate, and the resulting urethane derivatives have been separated by normal-phase high-performance liquid chromatography. This procedure allows resolution as diasteroisomers of the 2 enantiomeric classes (sn-1-MAG and sn-3-MAG), without the need of a chiral column, and to separate also the isomeric sn-2-MAG class; moreover, by introducing a chromophoric moiety, this reagent makes possible the ultraviolet detection of the analyte molecules. This procedure has been used to obtain the stereospecific analysis of the TAG fraction of extra virgin olive oil samples. The use of a nondestructive detector permitted the collection of the individual urethane classes; the fatty acid composition of each was determined by high-resolution gas chromatography, obtaining directly from the data the fatty acid distribution within each sn- position of TAGs. To validate this new method, the results have been compared with those obtained by 2 other procedures for TAG stereospecific analysis, and the obtained results were satisfactory since the proposed method gave data very similar to the other procedures.

HPLC separation and NMR structural elucidation of sn-1,2-, 2,3-, and 1,3-diacylglycerols from olive oil as naphthylethylurethane derivatives

In this study, sn-1,2-, sn-2,3-, and sn-1,3-diacylglycerols were isolated from olive oil, and their urethane derivatives (urethanes) were prepared. Normal-phase high-performance liquid chromatography (NP-HPLC) separation of the urethane isomers was performed and the separate classes were studied by nuclear magnetic resonance (NMR). The use of 1H NMR and homo- and heteronuclear 2D techniques provided a great amount of information in a very short time, particularly when a high-field NMR instrument (700 MHz) was used. Particularly diagnostic for this kind of compound was the glyceridic moiety that presents typical chemical shifts both for carbon and hydrogen. These studies show the usefulness of NMR spectroscopy to recognize clearly the sn-1,3- and, moreover, sn-1,2- with respect to sn-2,3-diacylglycerols, although very minor differences occur between them.

Prediction of isocratic nonaqueous reversed-phase high-performance liquid chromatography retention parameters and response factors of triacylglycerols detected by an ultraviolet-diode array-evaporative light-scattering on-line system

Nonaqueous reversed-phase high-performance liquid chromatography of 10 homogeneous triacylglycerol molecular species (TAG), both saturated and unsaturated, is carried out. The eluate from the column is detected by an ultraviolet diode array detector (DAD) on-line with an evaporative light-scattering detector (ELSD). The retention parameters (as selectivities, alpha) for 220 TAGs are determined, and the obtained values are related to the following structural parameters: total carbon number; mono-, di-, and triunsaturated fatty acid residues number/molecule; and monounsaturated fatty acid carbon number. Multiple regression analysis is carried out to obtain a relationship for the prediction of alpha values of any TAG when the same experimental conditions are used. In regard to the quantitative analysis of the separated TAG species, the dependence of response of the two on-line detectors on the aforementioned structural parameters is studied. Three different wavelengths (205, 210, and 215 nm) are considered for TAG detection by DAD; in each case, the obtained multiple regression model shows a good correlation between the dependent variable and predictive values of the TAG species (response factors and considered structural parameters, respectively). The ELSD gives responses exponentially related to injected amounts. Also, in this case, an attempt to relate the response factors of each considered detector to some structural parameters of TAG species is carried out. The results of this study are used to analyze the TAG fraction from an olive oil.

Inter- and intra-individual variability in food intake of elderly people in Perugia (Italy)

It has been shown that each individual has a considerable day-to-day variation (intra-individual variation) in his or her level of food consumption. A large intra-individual variation has adverse effects on the reliability of research studies. The effect of the intra-individual variation can be minimized by taking food intake records over several days. An increase in the number of days entails higher costs, and this could limit the practicability of the study. In the recent literature on the methodology of dietary surveys, there is a growing interest in the estimation of the number of days required to conduct a reliable dietary survey. Recent developments in statistical theory allow the problem of large intra-individual variability to be overcome. These new statistical techniques require knowledge of the intra- and inter-individual variability and the appropriate adjustment of the statistical results. The aim of the present study was to evaluate the number of days of recorded intake required to obtain an estimate of the components of variance (the inter-individual and the intra-individual variability) focusing on foods rather than nutrients.

[Influence of rapeseed oil on lipoprotein lipase activity in pigs (author's transl)]

Toxic activities in various animal species have shown for rapeseed oil. In this paper the influence of this oil on lipoprotein lipase activity of heart, liver and lung of pigs has been examined. The animals were fed with rapeseed oil with 40% erucic acid for 7, 15, 20 and 40 days. The control animals received olive oil. The results have shown a slight increase in the lipoprotein lipase activity in the heart of the pig after 20 days with rapeseed oil. In the liver this increase is particularly large in the pigs having been fed for 15 days both with rapeseed oil and olive oil. No differences were observed in the lung in the test and control animals with the only exception of animals fed for 20 days.

[Chemical composition and protein value of some baby foods (author's transl)]

The determination of lipids, available carbohydrates and unavailable carbohydrates, and of various minerals has been carried out on some baby foods; the value of the protein fraction has been similarly determined by the ultrafiltration method of the enzymic hydrolisate in vitro. Both the total protein content and the essential amino acid availability of the foodstuffs are satisfactory although generally speaking a slight decrease of the protein value has been found in this material as compared to the crude samples, due particularly to the breakdown of sulfur-containing amino acids. This breakdown is due probably to the high temperature reached during the technological processes at industrial level.