Giuseppe Procida

Determination of volatile compounds in cows' milk using headspace GC-MS.

The composition of the volatile fraction of milk from cows was investigated in a survey of milk samples using a headspace sampling technique and gas chromatography coupled to mass spectrometry analysis (GC-MS). Milk samples were collected from 12 farms, selected for similar management, breed and level of production. Farms were also grouped according to the type of forage in the ration: (1) hay; (2) hay and maize silage; (3) hay, maize silage and grass silages. Forty-one compounds in milk were isolated and identified from GC-MS headspace analysis. Quantitatively, the most representative chemical class was ketones (eight compounds, 170 microg/kg), followed by aldehydes (nine compounds, 63 microg/kg), alcohols (eight compounds, 36 microg/kg), and lower amounts of hydrocarbons (six compounds), sulphur compounds (three compounds), esters (four compounds) and terpenes (three compounds). The novel headspace sampling technique, and the consequent reduction of sample pre-treatment, allowed the identification of low-molecular weight volatile compounds, and reduced the risk of producing artefacts during analysis. Discriminant analysis was used to identify a classification criterion for milk samples, using type of forage in the ration as a grouping variable. Posterior probability error rate indicated that aldehydes provided one of the best discriminant criteria for grouping milks according to ration composition. When all 41 identified volatile compounds were included, discriminant analysis selected nine compounds (acetone, 2,3-butanedione, 2-butanone, ethanol, acetaldehyde, ethylacetate, ethvlisovalerate, dimethylsulphone) that did not fail the tolerance test and which correctly classified 100% of the original cases.

Solid-phase extraction and gas chromatographic analysis of phenolic compounds in virgin olive oil

Abstract A careful investigation on the potential application of solid phase extraction (SPE)-gas chromatography procedure in the analysis of phenol compounds in virgin olive oils was carried out. In doped refined olive oil samples a comparison between liquid/liquid and SPE extraction evidenced higher recovery when the C 18 sorbent phase was employed whereas, in the case of total suppression of residual sylanolic group (C 18 EC ), only contradictory data was obtained. The same procedures were carried out on 10 genuine samples of virgin olive oil. As observed with the standards, C 18 sorbent phase gave higher values compared to C 18 EC and the liquid/liquid extraction procedures. Satisfactory results were obtained in the detection of ligstroside aglycon but for the oleuropein aglycon the quantitative is not completely reliable for the overlap of some unknown no-phenol compounds.

Determination of volatile compounds in San Daniele ham using headspace GC-MS.

The volatile fraction of San Daniele hams was evaluated in barrows and gilts belonging to two commercial breeds. A group of 120 pigs, reared under the same conditions, were slaughtered, and the right ham seasoned/cured for 12 months, in accordance with the San Daniele Consortium protocol. At the end of ripening, 16 hams (four of each gender and breed) were selected and analysed for volatile composition, using a dynamic headspace gas chromatography-mass spectrometry (DHS-GC-MS) technique. Seventy five compounds belonging to eight different chemical groups were identified in the hams. Alcohols were the most abundant constituents (41.38%) followed by aldehydes (31.53%). The possibility of classifying hams according breed and gender, using volatile compounds as independent variables, was analysed by principal component analysis, alcohols were the most suitable compounds to discriminate hams. Data from a larger number of samples are required to validate the conclusions.

Composition of commercial truffle flavored oils with GC–MS analysis and discrimination with an electronic nose

Truffles are among the most expensive foods and their quality depends on their unique aroma, composed of complex mixtures of lipophilic volatile organic compounds (VOCs). There are many foods flavored with truffle, and oils are particularly common. Using DHS-GC-MS and an electronic nose (MOS), 18 samples of olive oil flavored with white and black truffles from the Italian market were subjected to a blind analysis. Qualitative and quantitative analysis with DHS-GC-MS detected the presence of 63 VOCs, 32 of which can be attributed to olive oil, also defective, and 19 to truffles, while 12 foreign compounds are of dubious origin (synthesis and/or demolition). The data obtained with the electronic nose (MOS), processed statistically, was able to discriminate the aromas coincident with the three species of truffle declared on the label (the white truffle Tuber magnatum and the black truffles Tuber melanosporum and Tuber aestivum), demonstrating the potential and reliability of this technique, confirming the established malpractice of the use of bismethyl(dithio)methane in black truffles flavorings.

Chemical composition and functional characterisation of commercial pumpkin seed oil

BACKGROUND Pumpkin (Cucurbita pepo L.) seed oil is a common product in Slovenia, Hungary and Austria and is considered a preventive agent for various pathologies, particularly prostate diseases. These properties are related to its high content of carotenoids and liposoluble vitamins. In this study the carotenoid (lutein and zeaxanthin), vitamin E (α- and γ-tocopherol) and fatty acid contents of 12 samples of commercial pumpkin seed oil were investigated together with the composition of the volatile fraction resulting from the roasting process. RESULTS The aromatic profile obtained from the commercial samples was directly related to the intensity of the roasting process of the crushed pumpkin seeds. The roasting temperature played a crucial role in the concentrations of volatile substances originating from Strecker degradation, lipid peroxidation and Maillard reaction. CONCLUSION The findings suggest that high-temperature roasting leads to the production of an oil with intense aromatic characteristics, while mild conditions, generally employed to obtain an oil with professed therapeutic characteristics, lead to a product with minor characteristic pumpkin seed oil aroma. The nutraceutical properties of the product are confirmed by the high content of α- and γ-tocopherol and carotenoids.

Changes in the volatile components of virgin olive oil during fruit storage in aqueous media

Storage of olives in sea water is a traditional way of fruit storage in olive oil production in Croatia that is still in frequent use. The changes of volatile compounds of olive oil, responsible for positive and negative odor properties that occur during this kind of fruit storage, were investigated. The influence of sea water was compared to brine and drinking water and with storage in the open air. The composition and content of volatile compounds were determined by dynamic headspace analysis with direct connection to gas chromatography and mass spectrometry. No significant differences were found among aqueous media. The olive oils from aqueous media had an essentially different composition and content of positive as well of negative volatile compounds in comparison to the reference sample and the samples stored in the air. The analytical method can give useful information about fruit storage before olive oil extraction.

Effects of including silage in the diet on volatile compound profiles in Montasio cheese and their modification during ripening.

Effects of including silage in the diet on volatile compound profiles and their modification during ripening of Montasio cheeses were examined. Twelve farms were selected and grouped according the type of forage in the ration: hay-based diets (four farms); hay and corn silage-based diets (four farms); and diets based on hay, corn silage and grass silages (four farms). For cheesemaking, 1000 kg of milk collected from two consecutive milkings was sampled from each farm and processed in the same cheese factory. Cheeses were ripened in the same cellar, in controlled humidity (78-85% relative humidity) and temperature (9-12 degrees C), until analysis. After 68 (62-74), 200 (194-206) and 360 (354-366) d of ripening, a cheese from each batch was analysed for moisture, protein and fat, volatile fatty acids (VFA) and volatile compounds. These latter were analysed by dynamic reverse carrier gas headspace gas chromatographic mass spectrometry (GC-MS) technique, scanning from m/z 29 to m/z 300 at 0.5 s cycle time. Total and individual VFA contents of cheeses did not differ between the different dietary treatments and increased linearly (P<0.01) during ripening, indicating that there were no appreciable defects of fermentation. Sixty-two volatile compounds were identified in the cheese samples: 12 aldehydes, 9 ketones, 16 alcohols, 17 esters, 2 hydrocarbons, 4 sulphur-containing compounds and 2 terpenes. Diet significantly affected the amount of total alcohols, ethanol, isobutanol, 1-penten-3-ol, 2-methyl-1-butanol and the sum of all the volatile compounds. Significant variations of 33 volatile compounds (9 aldehydes, 4 ketones, 6 alcohols, 10 esters, 1 hydrocarbons, 2 sulphur containing compounds, and 1 terpene) were observed during ripening. These results suggest that the influence of diet composition on volatile compounds of matured cheeses are related more to effects on microbial and chemical fermentations in cheese during ripening rather than to a direct transfer of molecules from milk.

Cerebrosides with antiproliferative activity from Euphorbia peplis L.

Two new cerebrosides have been isolated from the whole plants of Euphorbia peplis L. The structures were established by FT-IR spectroscopy, FAB MS, EI-MS, ESI-MS, 1D and 2D NMR spectroscopy. The structures of the cerebrosides were characterized as 1-O-beta-d-glycosides of phytosphingosines, which comprised a common long-chain base, (2S, 3S, 4R, 8Z)-2-amino-8 (Z)-octadecene-1,3,4-triol with 2-hydroxy fatty acids of varying chain lengths (C25, C22) linked to the amino group. The isolated compounds were shown to possess significant antiproliferative properties against cultured human tumor cell lines KB and IMR-32.

Study on volatile components in salami by reverse carrier gas headspace gas chromatography-mass spectrometry.

Salami are a typical seasoned sausage of Italy; a number of types are produced, according to local traditional recipes. As industrial production has taken place, a number of problems rise in obtaining products similar to the traditional ones. The use of selected microbial starters is permitted by Italian law for some years and at present, microbiological research is engaged in selecting starters similar to the ones isolated from traditional products, with the aim of obtaining organoleptic characteristics close to the ones of traditional recipes. A study was carried out concerning the characterisation of volatile components of salami by headspace capillary gas chromatography-mass spectrometry. As during the sampling step, analytes could reach the analytical column, the carrier gas rate was back flushed in the latter, while a pre column was used as cold trap. Then GC-MS analysis follows. By these techniques, we were able to highlight typical profiles of different salami, as well as monitoring the ripening of a traditional and a starter added salami. Main peaks are of fermentative origin, while also peaks from spices were detected. Ethyl propionate was used as internal standard to be able to normalise the peaks amounts.

Chemoenzymatic synthesis and antimicrobial activity evaluation of monoglucosyl diglycerides

Monogalactosyl diglycerides with medium to long fatty acid acyl chains, were prepared and examined for antimicrobial activity against Gram positive, Gram negative bacteria and fungi. The study of their in vitro antimicrobial activity confirms the significant activity of some monogalactosyl diacylglycerol analogues and establishes for the galactose series that the 1,2-disubstitution and the octanoyl chain are the proper structural features for the maximum activity.