Aroma compound recovery with pervaporation — Temperature effects during pervaporation of a muscat wine

A muscat wine, in which eight aroma compounds had been identified, was pervaporated through a poly(dimethyl siloxane) membrane at four different feed temperatures, 6, 15, 25 and 35 °C. Marked effects were observed in the partial fluxes of aroma compounds as the temperature was increased, a phenomenon which could be described by Arrhenius expressions in the equations used to mathematically describe the pervaporation process. Different aroma compounds were differently affected by the temperature changes, and this resulted in changes in concentrations in the permeate, both total and relative, of the aroma compounds studied and in their aroma values in the permeate. Knowledge of the temperature dependence of different aroma compounds is therefore of great importance in the optimization of the pervaporation process for aroma compound recovery.     

LC–MS/MS analysis of phenols for classification of red wine according to geographic origin,grape variety and vintage

A rapid LC–MS/MS method for quantification of phenols and polyphenols in authentic wine samples with unrivalled sensitivity was developed. Excellent limits of detection in the low μg L⁻¹ range were achieved. Reversed phase HPLC employing sub-2 μm particles as stationary phase allowed high-throughput analysis with analysis times of 10 min for 11 compounds. The phenolic pattern was assessed in 97 authentic wine samples (stored under identical conditions without further treatment or modification) comprising eleven geographical Austrian regions, six grape varieties and five vintages. Canonical discriminant analysis was applied to the data set showing the suitability of the (poly)phenolic spectrum for classification of the wine samples. The method allowed a geographic discrimination of several grape varieties and a grape variety based discrimination of four regions. As a novel finding excellent (poly)phenol-based differentiation of the five investigated vintages (2003–2007) was achieved.     

Development of volatile compounds during the manufacture of dry-cured "lacón," a Spanish traditional meat product

Volatile compounds were determined throughout the manufacture of dry-cured "lacón," a traditional dry-salted, and ripened meat product made in the north-west of Spain from the foreleg of the pig following a similar process to that of dry-cured ham. Volatiles were extracted by a purge-and-trap method and analyzed by gas chromatographic/mass spectrometry. One hundred and two volatile compounds were identified. In raw material, only 34 volatile compounds were found and at very low levels. The number of volatile compounds increased during processing. The substances identified belonged to several chemical classes: aldehydes (23), alcohols (9), ketones (15), hydrocarbons (37), esters (4), acids (3), furans (4), sulphur compounds (1), chloride compounds (1), and other compounds (4). Results indicated that the most abundant chemical family in flavor at the end of the manufacturing process was aldehydes, followed by hydrocarbons and ketones. Lipids were the most important precursor of flavor compounds of dry-cured "lacón."     

Influence of the salting time on volatile compounds during the manufacture of dry-cured pork shoulder “lacón”

The effect of the length of salting time on volatile compounds throughout the manufacture of dry-cured “lacón” was studied using a purge-and-trap extraction and GC/MS analysis. For this study, six treatments of “lacón” were salted with different amounts of salt (LS (3 days of salting), MS (4 days of salting) and HS (5 days of salting)). The total area of volatile compounds increased significantly (P < 0.001) as the length of salting time increased. Significant differences were found for the total area of all aldehydes for each salting time at the end of process. Hexanal presented the most relative abundance, showing highest content in HS treatments while LS treatments showed the lowest one at the end of salting, post-salting and drying-ripening stage. The influence of salting time on the content of 3-Octen-2-one was significant on salting stage (P < 0.001) and drying–ripening stage (P < 0.01). The salting time affected (P < 0.001) the relative abundance of esters at the end of salting and at the end of drying-ripening stage. The salting time affected significantly (P < 0.001) on alcohols content at the end of drying–ripening process. However, no significant effect of salt level (P > 0.05) was detected on total hydrocarbons and total furans at the end of process.     

Low temperature,continuous wine ‐ making by immobilized cells: A comparative study of the effect of temperature on volatile by ‐ products

Abstract

A comparison study concerning the formation of methanol, ethylacetate, propanol‐1, isobutanol and amyl alcohols (mixture of 2‐ methylbutanol‐1 and 3‐methylbutanol‐1) in continuous wine‐making by γ‐alumina, kissiris and alginates supported biocatalysts is performed in this investigation. The effect of temperature was also examined. Methanol content was not affected by the support, process and temperature, but the concentrations of the other above compounds were reduced by the reduction of the temperature in all studied supports. The percentage content of ethyl acetate in the total volatile determined plus methanol was higher in the case of immobilized cells than in free cells. Kissiris supported biocatalyst increased this parameter but the other and free cells decreased it. Propanol‐1, isobutyl‐alcohol and amyl alcohols as percentage on total volatiles determined plus methanol were less than those of free cells for all supports and temperatures studied. The effect of the improvement of the formation of volatiles on quality of the wine was examined by a taste test.     

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

Food Science and Biotechnology - Nineteen samples of Arabica and 14 of Robusta coming from various plantation were analysed by dynamic headspace capillary gas chromatography–mass spectrometry...     

Characterisation of the microflora of attiéké, a fermented cassava product, during traditional small-scale preparation

Attiéké is a fermented cassava product consumed mainly in Cote d'Ivoire. The aim of this study was to characterise the attiéké fermentation by examining products from 15 small-scale production sites at various stages of its preparation. For the preparation of attiéké, fresh cassava is grated to a pulp and inoculated with 10% of a spontaneous traditional inoculum. The inocula contained aerobic mesophiles at mean numbers of 8.2 x 10(7) cfu/g and lactic and acetic acids at mean concentrations of 0.2% and 0.1%, respectively. The mean pH was 5.0. Lactic acid bacteria were the dominant microorganisms in cassava pulp throughout fermentation with the mean numbers being 1.2 x 10(9) cfu/g after 15 h. The identification to the species level of microorganisms from one representative attiéké production of good quality showed that, at the start of fermentation, Leuconostoc mesenteroides subsp. mesenteroides was present in the highest numbers, accounting for 20% of all lactic acid bacteria. As the fermentation proceeded, this species was replaced by homofermentative lactic acid bacteria, Lactobacillus salivarius and Lactobacillus delbrueckii subsp. delbrueckii, present at 20% and 16%, respectively, and obligate heterofermentatives, Lactobacillus fermentum and Lactobacillus confusus at 12% and 10%, respectively, of total lactic acid bacteria in the flora at the end of fermentation. High numbers of acid-sensitive microorganisms, Bacillus circulans, Bacillus lentus, Enterobacter sakazakii, Enterobacter cloacae and Klebsiella pneumoniae subsp. pneumoniae, were transferred to the pulp in the inocula, but acidification to a mean pH of 4.4 with mean lactic and acetic acid concentrations of 0.59% and 0.2%, respectively, prevented their growth and reduced their numbers to less than 10(2) cfu/g at the end of fermentation. The mean numbers of Candida tropicalis, the main yeast present, remained relatively constant at about 10(5) cfu/g throughout attiéké production. The mean numbers of aerobic mesophiles decreased to below 10(2) cfu/g as a result of the steaming process. The finished attiéké had a mean pH of 4.4 and mean lactic and acetic acid concentrations of 0.6% and 0.1%, respectively.     

Characterisation by SPME–GC–MS of the volatile profile of a Spanish soft cheese P.D.O. Torta del Casar during ripening

The volatile profile of the Spanish soft cheese of the Protected Designation of Origin (PDO) Torta del Casar, made from raw ewes’ milk, was studied in four different stages of ripening (1, 30, 60 and 90 days) by the method of SPME–GC–MS. A total of 46 compounds were detected: 13 acids, 9 esters, 4 ketones, 7 alcohols, 3 aldehydes, 7 aromatic compounds and 3 compounds which could not be classified into those groups. Carboxylic acids were the most abundant group isolated; their levels significantly increased during ripening and comprised 61.5% of the total aroma extract at the end of ripening. At day 90, acids of microbial origin were the most abundant, followed by acids derived from amino acids while acids from lipolysis of triglycerides were the least abundant. Esters were the next most important group and their amount also increased significantly during maturation, as did ketones, while alcohols content slightly decreased at the end of the ripening. At day 90, the compounds at highest levels were acetic acid, 3-methylbutanoic acid, butanoic acid propyl ester and 2-butan-one; so these compounds, due to their high levels and their low threshold value could play an important role in the final aromatic profile of this cheese.     

Variation in the content of the main guaianolides and sugars in Cichorium intybus var. “Rosso di Chioggia” selections during cultivation

Cichorium intybus var. “Rosso di Chioggia” is a chicory variety cultivated predominantly in Northeastern Italy and highly appreciated for its bitter taste. The commercial portion of the plant, used as food, comprises the innermost leaves (head) of plants harvested during the first year of growth; the outermost leaves and the roots are considered wastes. Three selections belonging to this variety have been analyzed for guaianolide and sugar contents and compared with the commercial product (head), roots and outermost leaves. The qualitative and quantitative evaluations of both classes of compounds were achieved by densitometric HPTLC. The analytical data showed a high variability during the stages of growth, both among the parts of the plant and among the three selections of chicory considered. With particular reference to the heads, a sensory bitterness evaluation method was set up in order to find a correlation between the analytical data and the bitter taste.     

Relating physicochemical and microbiological safety indicators during processing of linguiça,a Portuguese traditional dry-fermented sausage

Linguiça is a Portuguese traditional fermented sausage whose microbiological quality and safety can be highly variable. In order to elucidate risk factors and the particularities of the manufacturing technology that explain the between-batch variability in total viable counts (TVC), Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in the product; microbiological and physicochemical characterisation of linguiça at five stages of production (i.e., raw pork meat, mixed with ingredients, macerated, smoked and ripened) was carried out. A total of six production batches were surveyed from two factories; one utilised curing salts and polyphosphate in their formulation (Factory II). The delayed fermentation in the nitrite-formulated sausages was partly responsible for the increase (p < 0.01) in Enterobacteriaceae, S. aureus and L. monocytogenes from raw meat (3.21 log CFU/g, 1.30 log CFU/g and 22.2 CFU/g, respectively) to the end of maceration (4.14 log CFU/g, 2.10 log CFU/g and 140 CFU/g, respectively) while the better acidification process in the nitrite-free sausages (Factory I) led to lower counts of S. aureus (2.64 log CFU/g) and L. monocytogenes (10 CFU/g) in the finished products. In Factory II, although L. monocytogenes entered the chain at the point of mixing, it became steadily inactivated during smoking and ripening (< 50 CFU/g), despite the initially-delayed fermentation. Nitrite had a strong effect on reducing Enterobacteriaceae throughout smoking (r = − 0.73) and ripening (r = − 0.59), while it failed to control the growth of S. aureus. The main hurdle preventing the development of S. aureus in linguiça is the pH, and other factors contributing to its control are: longer ripening days (p = 0.019), low S. aureus in raw meat (p = 0.098), properly-washed casings (p = 0.094), and less contamination during mixing (p = 0.199). In the case of L. monocytogenes, at least three hurdles hinder its development in linguiça: low a_w (p = 0.004), low pH (p = 0.040) and nitrite (p = 0.060), and other factors contributing to its control are: longer ripening (p = 0.072) and maceration (p = 0.106) periods, lower a_w at the end of smoking (p = 0.076) and properly-washed casings (p = 0.099). Results have shown that there is a need to standardise the productive process of linguiça, to optimise the initial acidification process, and to reinforce proper programmes of quality control of ingredients and good hygiene practices, so as to minimise the introduction of Enterobacteriaceae and pathogens from external sources.     

Volatile flavour composition of cooked by-product blends of chicken,beef and pork: a quantitative GC–MS investigation

Volatile flavour composition of cooked chicken (CB), beef (BB) and pork (PB) by-product blends was investigated using gas chromatography–mass spectrometry (GC–MS) and the results were compared with those for cooked chicken white muscles (CM), beef shoulder muscles (BM) and pork shoulder muscles (PM), respectively. The total volatile flavour concentration of CB (4828 μg/kg sample) was three times higher than that observed for CM (1604 μg/kg sample). In BB and PB, the total volatile concentration was lower than that observed for their muscle counterparts. Aldehydes, alcohols and nitrogen- and/or sulphur-containing compounds dominated the volatile flavour profiles of CM, BM and PM while a marked dominance of alcohols was evident for CB and BB. The concentration of aldehydes in BB and PB was lower by about 66 and 70%, respectively, than that evident for the corresponding cooked muscles. The difference between the concentration of aldehydes in CM and CB was ∼7%. These differences between the volatile flavour profiles of cooked muscle samples and the corresponding by-product blends may be attributed to the compositional differences in aroma precursors in the samples. This study demonstrated that the volatile flavour compounds in cooked meat by-products are recoverable, but a careful blending of different by-products of a particular species in appropriate proportions may be necessary to generate an aroma similar to that of the respective cooked muscles.     

Development,validation and application of a specific method for the quantitative determination of wine esters by headspace-solid-phase microextraction-gas chromatography–mass spectrometry

A method for specifically quantifying 32 apolar esters in wine is reported that employs head space solid phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC–MS). A dozen esters were studied for the first time in wines, among them methyl trans-geranate, never reported in red wines until now. The target esters were apolar but bore a broad range of functional groups and have concentrations ranging from mg/l to ng/l levels; polar esters being effectively extracted by dichloromethane. Extraction and desorption conditions were optimised to obtain the best compromise for the simultaneous analysis of all 32 studied esters. To provide specificity for the method, deuterated ethyl esters were used as internal standards. These were ethyl-d₅ butyrate, hexanoate, octanoate and cinnamate, synthesised from the appropriate acyl chloride and ethanol-d₆. The esters were quantified in the wines with satisfactory repeatability (1.8% < RSD < 11.2%), reproducibility (1.5% < RSD < 15%), sensitivity (0.4 ng/l < LOQ < 4 μg/l), accuracy and specificity. The validation was carried out with several wine types as matrices (red, dry and sweet white). The optimised method was applied to 19 French wines and the results confirmed some well established oenological principles and opened prospects for further study on wine esters that had not been previously measured.     

Phenolic composition,antiproliferative and antiulcerogenic activities of a polyphenol-rich purified extract from açai (Euterpe oleracea) fruits

The bioactivity and phytochemical composition of a partially purified extract of açai (PPEA), concentrated in phenolic compounds (PC) and without the presence of macronutrients, were investigated. The major PC quantified by UHPLC-DAD-LTQ-Orbitrap MS-MS/MS in the PPEA are anthocyanins. In vitro, PPEA showed a cytostatic effect on the K-562 lymphoid leukaemia at a concentration of 40 μg PC mL⁻¹, with a GI₅₀ equal to 1.08 μg PC mL⁻¹. In vivo, the extract did not promote acute toxicity in mice in any of the doses tested. The extract displayed gastroprotective activity in rats treated orally with 16, 48 and 160 mg PC kg⁻¹, with a significant decrease in the ulcerative lesion index, compared with the negative control. The lack of toxicity and the bioactivity of the PPEA show that this extract is beneficial to health and useful as a commercial food additive containing natural violet colourant, with pharmaceutical and functional potentials.