Alysis of the volatile constituents of food by headspace GC-MS with reversal of the carrier gas flow during sampling

Characterization of Arabica and Robusta volatile coffees composition by reverse carrier gas headspace gas chromatography-mass spectrometry based on a statistical approach

Nineteen samples of Arabica and 14 of Robusta coming from various plantation were analysed by dynamic headspace capillary gas chromatography-mass spectrometry to characterize the volatile fraction of green and roasted samples and the relationships of the same species with geographical origin. As concerns green beans, Arabica species appear characterized by high content of n-hexanol, furfural and amylformate, while Robusta species by greater content of ethylpyrazine, dimethylsulfone and 2-heptanone. Four variables, 4-methyl-2,3-dihydrofuran, n-hexanol, limonene and nonanal, appear involved in the characterization of the geographical origin of the analysed samples. The volatile fraction of the roasted Arabica samples, appear characterized by high content of pyridine, diacetyl, propylformate, acetone and 2,3-pentanedione, while Robusta samples by high content of methylbutyrate, 2,3-dimethylpyrazine and 3-hexanone. Considering geographical origin of the analysed samples, four compounds appear involved, in particular 2-butanone, methylbutyrate, methanol and ethylformate. Very accurate (error rate lower than 5%) rules to classify samples as Arabica or Robusta according to their compounds profile were developed.

Influence of partial replacement of NaCl with KCl on formation of volatile compounds in Jinhua ham during processing

The influence of partial replacement of NaCl with KCl on formation of volatile compounds during Jinhua ham processing was evaluated using GC/MS system. Jinhua ham was treated with either 100% NaCl (I) or 60% NaCl and 40% KCl (II). Formation of volatile compounds increased in Jinhua hams during processing for both salt formulations, particularly at the end of the salting period. There were differences in volatile compound formation between formulations I and II after 45 days of processing. Contents of lipid-derived volatiles (hexanal) and Strecker aldehydes (2-methylbutanal and 3-methylbutanal) were higher in Jinhua hams treated with formulation II after 45 days of processing. Partial salt replacement of NaCl with KCl changed formation of volatile compounds in Jinhua hams and may have affected the flavor of finished products.

Effects of stocking density and supplement level on milk production and cheese characteristics in Brown cows grazing on mountain pasture

Twenty-eight Brown cows were maintained on a mountain pasture for a period of 40 days and assigned to 4 groups following a factorial design 2 stocking density (0.7 and 1.4 cows/ha)x2 supplement levels (2.4 and 4.8 kg organic matter (OM)/d). Herbage intake, animal body condition score (BCS), milk yield, milk chemical and coagulation properties, cheese composition, rheology and sensory characteristics were measured. The average herbage intake was 12.2 kg OM/d, with a significant effect related to stocking density (low, 13.1 v. high, 11.4 kg OM/d). BCS variation was always negative and changed with supplement level, although with no statistical significance (-0.43 points on average). Milk yield was lower for the group with lower availability of herbage (low supplement and high stocking density: 15.9 kg/d), whereas it was comparable among others groups (16.9 kg/d on average). The group with high supplement and low stocking density produced milk with worse cheese making properties. Cheese composition analyses showed an effect of supplement level on calcium content, and on parameters for degree of ripening, such as nitrogen fractions and lipolysis index. As for the textural parameters, hardness and gumminess were found to be higher with the low level of supplement. The different level of supplementation could differentiate the groups on the basis of the sensory perception of cheese.

Aloe exudate: characterization by reversed phase HPLC and headspace GC-MS

From the leaves of aloe, a succulent plant, a dried exudate commonly called aloe can be obtained, which is used as a natural drug for its cathartic effect and is widely employed as a bittering agent in alcoholic beverages. This investigation provides a tentative characterization of several commercial aloe exudates carried out both by reversed phase HPLC and by headspace GC-MS analysis. By means of HPLC the derivatives were evaluated, and by GC-MS the volatile fraction was investigated. Qualitative and quantitative differences among the constituents in various samples of different origins were found. In particular, these were evident in the HPLC profile of Kenya aloe and an Aloe barbadensis sample, which exuded a high content of isoaloeresin D and aloins, whereas GC-MS analysis showed the presence of anisole exclusively in Kenya aloe samples. Moreover, the results obtained by means of the latter technique suggested a reason for the prevailing use of Mosselbay and Port Elizabeth aloes in bitter spirits formulation.

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.

A method to mimic and to study the release of flavour compounds from chewed food

A method for analysing the flavour release from chewed food has been developed. Flavour release is studied in an artificial mouth simulating the process of chewing and using fluid model systems, in our case aromatised oil in water emulsions. The fast transfer of volatile substances from the chewpulp into the gaseous phase is followed up by comparing six quickly taken gas samples. Volatile substances are analysed by means of a special technique which includes cryofocusing and capillary gas chromatography. As a wide spectrum of individual volatile substances is considered, systematic investigations into the flavour release from food under mouth-typical conditions are possible.