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European Food Research and Technology

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ISSN (Print) 1438-2377 - ISSN (Online) 1438-2385
Published by Springer-Verlag

[2216 journals]

Efficient induction of inulin fructotransferase by inulin and by difructose anhydride III in Arthrobacter aurescens SK 8.001
- Abstract: Inulin fructotransferase (IFTase; EC 4.2.2.18) has received great attention mainly due to its application in producing difructose anhydride III (DFA III), which is a novel functional sweetener. The object of this study was to investigate the induction of IFTase in Arthrobacter aurescens SK 8.001 with various carbon sources, especially inulin and DFA III. IFTase production could be significantly promoted by the supplement of inulin (5–50 g/L) and DFA III (5–20 g/L). Inulin at high initial concentrations gave no indication of catabolite repression, whereas 30 and 40 g/L DFA III intensely inhibited cell growth and IFTase activity. No fructose was detected in broth throughout the cultivation with inulin, and inulin was converted into DFA III and minor fructooligosaccharides. And when DFA III was the carbon source, DFA III was the only sugar detected in the broth. In conclusion, both DFA III and inulin are effective for IFTase induction, and inulin with higher IFTase activity proved to be a more potent inducer.
  PubDate: 2013-06-01
Enhancements of isoflavone aglycones, total phenolic content, and antioxidant activity of black soybean by solid-state fermentation with Rhizopus spp.
- Abstract: In the present study, a solid-state fermentation process of black soybean was developed. Three filamentous fungi including Rhizopus oligosporus (BCRC 31996), R. oligosporus (NTU-5), and Rhizopus oryzae (BCRC 30894) were cultivated with steam-cooked intact and dehulled black soybeans. It was found that fermentation enhanced the total phenolic and isoflavone aglycone content as well as antioxidant activity of the black soybean methanol [80 % (v/v)] extracts. Among the three candidates, R. oligosporus BCRC 31996 was chosen as the working strain, and dehulled Tainan NO.3 black soybeans were used as the substrate based on the relatively high total phenolic content, isoflavone aglycone accumulation, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect of the fermented extracts. In a 6-day fermentation, extracts of the fermented dehulled black soybeans yielded higher total phenolic content (2,876.2 μg/g) which was 1.16 times of the result from the intact soybean extracts. The DPPH scavenging effect of the fermented dehulled black soybean extract reached its maximum on the third day. The activity of β-glucosidase of dehulled black soybean samples increased with time and resulted in accumulation of isoflavone aglycones. The product of solid-state black soybean fermentation serves as a functional ingredient in the products of nutritional supplements and health foods.
  PubDate: 2013-06-01
Application of enzyme in aqueous extraction of sesame oil
- Abstract: The oil recovery of the traditional process of extracting sesame oil by aqueous method could be improved by adding enzyme. Sesame oil was extracted under aqueous extraction conditions using three kinds of enzymes, which were papain, trypsin and cellulase. The optimal conditions were pH 7.0, 50 °C and extraction time 3 h with constant shaking at 80 rpm. The enzyme dosage and the enzyme proportion were researched by orthogonal experiment. The result indicated that the enzymes significantly improved the oil recovery. When the enzyme hydrolysis was performed with complex enzyme of papain 6,000 U, trypsin 400 U and cellulase 250 U/g oilseed, higher oil recovery (87.58 %) was achieved than the traditional aqueous extraction processing, and the oil was extremely fragrant. Moreover, the clear oil could fall directly from the centrifuge tube which greatly reduced the difficulty of separating oil.
  PubDate: 2013-06-01
Electrochemical detection of pyrosine with electrochemically reduced graphene oxide modified glassy carbon electrode
- Abstract: Pyrosine detection and quantification was reported by voltammetry with the electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The differential pulse voltammograms of pyrosine on the modified GCE showed that pyrosine can be sensitively detected, which may be attributed to the large surface area of ERGO and the improved electron transfer ability of ERGO compared to graphene oxide. The effect of supporting electrolyte and its concentration on the detection of pyrosine was also investigated in this paper. The ERGO modified GCE showed a linear concentration range between 1.6 and 374 μmol L−1 of pyrosine with a correlation coefficient of 0.9972, and the detection limit was as low as 1.2 × 10−8 mol L−1 (signal-to-noise ratio of 3).
  PubDate: 2013-06-01
Beneficial effects of Trichoderma genus microbes on qualitative parameters of Brassica rapa L. subsp. sylvestris L. Janch. var. esculenta Hort.
- Abstract: The consumption of vegetables and fruits has always been seen as health promoting. One group of vegetables that were already used for medicinal purposes in ancient times and are now seen as possibly cancer protective are vegetables of the Brassica genus. The protective effect of brassicas against cancer may be due to their relatively high content of glucosinolates. Certain hydrolysis products of glucosinolates have shown anticarcinogenic properties. However, not properly cooking procedures and storage could drastically reduce the content of glucosinolates in Brassicaceae plants. This study aims to assess whether the use of agronomic techniques can increase the content of glucosinolates in Brassica plants, in order to offset these losses. For this purpose were used strains of beneficial microorganisms of Trichoderma harzianum TM10, T. atroviride P1, already known biocontrol agents, and their metabolites harzianum acid and 6-pentyl-α-pyrone on plants of Brassica rapa subsp. sylvestris var. esculenta ecotype “Sessantino” (called with the trivial name “friarielli” in the south of Italy where this variety is very popular and consumed). Moreover, the antioxidant activity and ascorbic acid content were determined on plant extracts, followed by liquid chromatography–mass spectrometry analysis of glucosinolates. In order to obtain the extraction of constituents from plant material, microwave-assisted extraction was used. Results obtained showed that the use of Trichoderma and its metabolites determined an increase in glucosinolates in plants of B. rapa. Accordingly, the proposed method could be used on other plants of food interest to increase their nutritional properties.
  PubDate: 2013-06-01
Analysis of phytosteryl and phytostanyl fatty acid esters in enriched dairy foods: a combination of acid digestion, lipid extraction, and on-line LC-GC
- Abstract: Qualitative and quantitative methods for the analysis of intact phytosteryl/phytostanyl esters in enriched dairy products with substantial amounts of protein and fat were established. Lipids were extracted after acid digestion in order to achieve a complete extraction of the esters. The extracted lipids were separated via liquid chromatography on a normal phase, and the fraction containing the phytosteryl/phytostanyl esters was subsequently transferred on-line and analyzed by means of capillary gas chromatography. The applicability of the method was demonstrated for the analysis of intact phytosteryl/phytostanyl fatty acid esters in enriched yogurt, cheese-based spread, and milk. The approach enables the determination of individual phytosteryl/phytostanyl esters as well as of their total contents and provides detailed information on the distributions of esterified phytosterols/phytostanols and fatty acids. The employed approach complements the existing GC-based methods for the analysis of phytosteryl/phytostanyl esters in low-fat and fat-based products and thus creates a base for authenticity assessments of these types of novel foods.
  PubDate: 2013-06-01
A comparative study of oat (Avena sativa) cultivars as brewing adjuncts
- Abstract: Brewing with high levels of unmalted oats (Avena sativa) has proven to be successful despite their high contents of β-glucan, protein, and fat. However, little is known about the effect of different oat cultivars on the quality and processability of mashes and worts. Therefore, the aim of this study was to compare the mashing performance of eight oat cultivars, selected because of their low contents of β-glucan, protein, fat, and/or high starch content, when substituting 20 or 40 % barley malt. For this purpose, seven husked (A. sativa L. ‘Lutz’, ‘Buggy’, ‘Galaxy’, ‘Scorpion’, ‘Typhon’, ‘Ivory’, ‘Curly’) and one naked oat cultivar (A. sativa var. nuda ‘NORD 07/711’) were fully characterized using standard methods, Lab-on-a-Chip capillary electrophoresis, and scanning electron microscopy. The rheological behavior of mashes containing up to 40 % of each oat cultivar was measured during mashing by applying a Physica MCR rheometer. In addition, the quality of worts obtained from laboratory-scale mashing trials was analyzed particularly with regard to their cytolytic, proteolytic, and amylolytic properties. The substitution of up to 40 % barley malt with husked or naked oats resulted in significantly higher pH values, β-glucan contents, and viscosities as well as significantly lower soluble nitrogen and polyphenol contents, color values, filtration rates, and apparent attenuation limits. Naked oats contained significantly less β-glucan as well as more protein and starch than the seven husked oat cultivars. The replacement of barley malt with naked oats resulted in a constant extract yield, whereas the use of husked oats caused significant extract losses.
  PubDate: 2013-06-01
Biliverdin: the blue-green pigment in the bones of the garfish (Belone belone) and eelpout (Zoarces viviparus)
- Abstract: Little is known about the bluish-green color of the skeleton and bones of the garfish (Belone belone) and eelpout (Zoarces viviparus). Most of the few, contradictory reasons given favor either the iron(II) phosphate, vivianite, or the heme degradation product, biliverdin, but all lack documented spectroscopic confirmation. Our aim was to identify and quantify this blue-green substance and to investigate more precisely its location within the colored parts of these fish species. First, we found that vivianite was not indicated by the iron and phosphate levels in fish samples, whereas biliverdin was confirmed in the blue-green matrices both by UV–Vis (maxima at 376 and 666 nm) and FTIR spectroscopy, and by HPLC–MS/MS (molecular ion m/z [M + H]+ = 611) after sample preparation involving solvent extraction, methylation (yielding biliverdin dimethyl ester), and solid-phase extraction. The overall average garfish biliverdin recovery rate by HPLC–UV was 72.3 %; the average biliverdin content of the vertebral column (including the periosteum) was 23.49 μg/g; periosteum, 61.70 μg/g; and spinal process (Processus spinosus), 24.3 μg/g. Analysis of amino acid distribution in colored and non-colored fish matrices conformed high proportions of hydroxyproline in the former (periosteum 7 %, spinal processes 7.6 %), suggesting that biliverdin has a specific affinity for the structural protein collagen, and not for the bone itself. Finally, all methods confirmed the presence of biliverdin in collagen-rich tissues (periosteum and spinal processes) of garfish and eelpout, and we established a new method for the detection of biliverdin at low concentrations in structural proteins.
  PubDate: 2013-06-01
Differentiation of fish species by PCR-based DNA analysis of nuclear genes
- Abstract: Food control laboratories are confronted with new challenges in respect to fishery product authentication; examples are identification of hybrids (e.g. in case of catfish, tilapia, sturgeon, snapper) and assignment of fish to certified stocks. Against this background, differentiation of fish species and populations by polymerase chain reaction (PCR)–based DNA analysis of nuclear genes has become of considerable importance as a tool for the completion of mitochondrial gene analysis. Four applications of nuclear gene analysis are presented: (1) fish species identification using the intronless rhodopsin RH1 gene; (2) detection of “fish” as an allergenic foodstuff by means of universal primers amplifying a segment of a parvalbumin gene; (3) differentiation of cod (Gadus morhua) from various fishing grounds by exon-primed intron-crossing PCR of a parvalbumin gene intron; (4) detection of hybridization between North Atlantic redfish species (genus: Sebastes) by restriction fragment length polymorphism analysis of amplicons obtained from the second intron of the 7S ribosomal protein gene.
  PubDate: 2013-06-01
Multiplex real-time PCR for the detection and quantification of DNA from duck, goose, chicken, turkey and pork
- Abstract: Meat products made from liver of poultry like duck and goose are popular and often sold as specialities for high prices. As the prices for the basic raw material are high, fraud may be attractive for producers. To prevent consumers from fraud, official control authorities survey such products. In this work, a quantitative multiplex PCR was developed determining the proportion of DNA and meat fractions of turkey, chicken, duck, goose and pork. The precision and accuracy of the PCR system was investigated. To examine the possibility of determining the meat fractions according to the recipe, reference material was produced and different liver–meat products from the market were analysed. For major components, the measurement uncertainty revealed to be at 39 %. For minor components, it was estimated to be 124 %. The results showed that this pentaplex real-time-PCR system is suitable to control the meat properties of such products although measurement uncertainty may be high.
  PubDate: 2013-06-01
Key aroma volatile compounds of gulupa (Passiflora edulis Sims fo edulis) fruit
- Abstract: By application of the aroma extract dilution analysis of gulupa (Passiflora edulis Sims fo edulis), fruit pulp extract obtained by solvent-assisted flavour extraction, and also comparison of chromatographic, spectroscopic (mass spectrum), and odour properties with standards, β-ionone, γ-nonalactone, ethyl butanoate, and ethyl cinnamate were identified as volatiles exhibiting the highest flavour dilution (FD) factor. Among the nineteen odour-active compounds of gulupa, only those showing the highest FD factors were quantified by stable isotope dilution assay. After calculation of odour activity values (OAVs; ratio of concentration to odour threshold in water), ethyl butanoate, ethyl hexanoate, and β-ionone were identified as key aroma compounds in gulupa, responsible for the fruity and floral odour notes.
  PubDate: 2013-06-01
Effect of temperature and starch concentration on the creep/recovery behaviour of the grape molasses: modelling with ANN, ANFIS and response surface methodology
- Abstract: In this study, the effect of starch concentration (5, 7.5 and 10 %) and temperature (60, 70 and 80 °C) on the creep and recovery behaviour of grape molasses was investigated. Adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) models were established for the prediction of the compliance values (J(t)) based on temperature, starch concentration and time of the creep or recovery phases. The root mean square error, mean absolute error and R 2 values were used for the comparison of the models which showed that the ANFIS model performed better than the ANN model for the desired purpose. The Burger model fitted the J(t) versus time data with R 2 values ranging from 0.987 to 0.999. Response surface methodology (RSM) was performed to investigate the dependency of the creep (G 0 , G 1 , n 0 and n 1 ) and recovery (J KV , B, C, J max , J ∞ and % recovery) parameters to temperature and starch concentration. As a result of this study, it was observed that deformation of the grape molasses samples increased with decrease in starch concentration and increase in temperature. The gel strength (S) values of the samples were also calculated and modelled by RSM. As increase in starch concentration caused an increase in S value, there was an inverse proportion between the temperature and S value.
  PubDate: 2013-06-01
Stability of hydroxycinnamic acids and caffeine from green coffee extracts after heating in food model systems
- Abstract: This study was designed to characterize the stability of hydroxycinnamic acids and caffeine obtained from green coffee beans in the form of lyophilized extract (GCE) during heating after supplementation to model systems with saccharose, potato starch, egg white protein, and sunflower oil. Also the addition of iron ions was used. Systems were prepared as a mixture of GCE with a single substance or in a more complex matrix. Heating was carried out at 180 °C for 0.5 and 1 h. Because of the saccharose content, some systems were heated only at 110 °C. The losses of hydroxycinnamic acids in heated systems ranged from 18 to 84 %, and the caffeine from 1.5 to 10 %. The presence of sunflower oil in the systems had the greatest influence on hydroxycinnamic acids degradation. However, in case of the system of each of the examined substances with the coffee preparation, an increased degradation of hydroxycinnamic acids resulting from the introduction of ferrous ions into the systems was observed. Earlier results concerning antioxidant activity of systems containing GCE allow to conclude that the degradation of hydroxycinnamic acids was weakly related to the decrease in antioxidant activity.
  PubDate: 2013-06-01
Establishment and preliminary application of oligonucleotide microarray assay for detection of food-borne toxigenic microorganisms
- Abstract: Rapid, high-throughput and accurate detection and identification of food-borne toxigenic microorganisms is crucial for food safety nowadays. An oligonucleotide microarray was designed and established and was applied to detect common food-borne toxigenic microorganisms in this study. PCR amplification of marker genes and 16S rRNA gene of 14 toxigenic bacteria and fungi using specific primers and oligo probes residing in these genes were employed and designed to fabricate the microarray. Optimization of hybridization conditions was implemented. The optimal conditions for hybridization were 51 °C for 30 min. Furthermore, the ratio of biotin labeled to unlabeled primer for PCR amplification was also optimized to enhance specific hybridization of the microarray. Specificity, sensitivity (710 CFU/mL), and reproductivity assessment confirmed the practicability of the microarray. Finally, this microarray was successfully applied to detect 6 common toxigenic microorganisms from 328 food samples. The established microarray may provide potential for rapid detection and identification of toxigenic microorganisms from foods.
  PubDate: 2013-06-01
Application of a new sampling device for determination of volatile compounds released during heating olive and sunflower oil: sensory evaluation of those identified compounds
- Abstract: This work has applied a system for characterizing volatile compounds generated during the heating of oils, based on solid-phase extraction–gas chromatography–mass spectrometry. The system has been applied to sunflower and extra virgin olive oil at kitchen conditions, heating from room temperature to 80° above their smoking point. The work identified twenty-three compounds, mainly saturated and unsaturated aldehydes, and alkanes; carboxylic acids were present in lower concentrations. During heating, the stability of each oil was found to be different. The alkanals were produced in greater quantities in the sunflower oil. Alkanes were found in higher concentration in the olive oil and showed no significant variation in either of the oils as the temperature changed. And a relationship between the quantity of aldehydes released at the highest temperature and the percentage of fatty acids from which those aldehydes originated in each oil was found. The importance of the unsaturated aldehydes in the deep-fried odor was also exposed in this study.
  PubDate: 2013-06-01
Dark chocolate’s compositional effects revealed by oscillatory rheology
- Abstract: In this study, two types of oscillatory shear rheology are applied on dark chocolate with varying volume fraction, particle size distribution, and soy lecithin concentration. The first, a conventional strain sweep, allows for the separation of the elastic and viscous properties during the yielding. The second, a constant strain rate sweep, where the strain rate amplitude is fixed as the frequency is varied, is analyzed to obtain Lissajous curves, dissipated energy, and higher order nonlinear contributions. It is shown that chocolate exhibits complex nonlinear behavior, namely shear thinning, shear thickening, and strain stiffening. The effects on this behavior related to volume fraction, particle size distribution, and lecithin concentration are investigated, and comparison with simple monodisperse hard-sphere suspensions is made.
  PubDate: 2013-06-01
Colorimetry and photoacoustic spectroscopy as a suitable tool for determination of fat-free cocoa solids in dark chocolates
- Abstract: Laser photoacoustic spectroscopy (PAS) and colorimetry have been used to rapidly and accurately determine the content of fat-free cocoa solids in dark chocolates. Both techniques are inexpensive and require only a one-time calibration step versus a method capable of absolute concentration measurement (for example HPLC). Once the response of PAS and/or colorimetry has been obtained, the content of fat-free cocoa solids in dark chocolates can be determined directly (i.e. without any sample preparation including the process of extraction) from the calibration curves and the experimentally measured microphone signal (in PAS studies) and colorimetric indices L* and ΔE* (in colorimetric investigations). Both colorimetric indices and PA signals correlate positively with the content of fat-free cocoa solids. The correlation is highly linear over a wide concentration range (25–50 %).
  PubDate: 2013-06-01
Increased esters and decreased higher alcohols production by engineered brewer’s yeast strains
- Abstract: Esters and higher alcohols produced by yeast during the fermentation of wort have the greatest impact on the smell and taste of beer. Alcohol acetyltransferase, which is mainly encoded by the ATF1 gene, is one of the most important enzymes for acetate ester synthesis. Cytosolic branched-chain amino acid aminotransferase, on the other hand, which is encoded by the BAT2 gene, plays an important role in the production of branched-chain alcohols. The objective of this study is to construct engineered brewer’s yeast strains that produce more acetate esters and less higher alcohols. Industrial brewer’s yeast strain S5 was used as the parental strain to construct ATF1 overexpression and BAT2 deletion mutants. The engineered strains S5-2 and S5-4, which feature partial BAT2 allelic genes replaced by the constructed ATF1 overexpression cassette, were obtained. The ester production of the engineered strains was observed to increase significantly compared with that of the parental cells. The concentrations of ethyl acetate produced by the engineered strains S5-2 and S5-4 increased to 78.88 and 117.40 mg L−1, respectively, or about 7.7-fold and 11.5-fold higher than that produced by parental S5 cells. The isoamyl acetate produced by S5-2 and S5-4 also increased to 5.14 and 9.25 mg L−1, respectively; by contrast, no isoamyl acetate was detected in the fermentation sample of the parental strain S5. Moreover, S5-2 and S5-4, respectively, produced about 65 and 51 % of higher alcohols produced by the parental strain. The increase in acetate ester content and decrease in higher alcohol concentration shown by the engineered brewer’s yeast strains at the end of fermentation process indicate that the new strains are useful in future developments in the wheat beer industry.
  PubDate: 2013-06-01
The importance of solvent type in estimating antioxidant properties of phenolic compounds by ABTS assay
- Abstract: ABTS assay belongs to the most popular methods employed for estimating antioxidant activity. However, researchers seldom pay attention to specific factors influencing the determination of antioxidant activity of the examined compounds and mixtures. The paper shows that the type of alcohol used significantly influences the estimation of antioxidant activity of phenolic compounds in ABTS assay, namely that their antioxidant activity increase with the lengthening of the aliphatic chain in alcohol. It results rather from the changes in ABTS •+ solvatation energy by the employed alcohols than from dissociation variations of phenolic compounds. The obtained results point to the difficulties in the correct estimation of the real antioxidant properties of plant and food extracts by ABTS assay. The presented results have also an ecological implication as they refer to the difference in estimation of antioxidant properties of compounds resulting from the replacement of toxic methanol by GRAS (Generally-Recognized-As Safe) solvents, ethanol and propanol.
  PubDate: 2013-06-01
Impact of environmental water activity on E. faecium thermoresistance and possibility of regeneration of heat-damaged cells in pasteurised canned meat
- Abstract: Production of high-quality tinned meat requires optimisation of sterilisation and pasteurisation processes. Changes in conditions during heating (a w , pH) affect thermoresistance of microorganisms and the possibility of their regeneration following the heating process. Inactivation models of microorganisms used in practice do not take into account these factors. The aim of this study was to determine the influence of the decreasing water activity of the medium during heating and recovery on the thermoresistance of Enterococcus faecium and determine z aw (the distance of a w from a wopt = 1 which leads to a tenfold reduction in D value) and z′ aw (the distance of a w from a′ w of the recovery medium which leads to a tenfold reduction in D value) parameters. The performed experiments revealed that Enterococcus faecium PCM 1859 thermoresistance increased during heating in the environment characterised by reduced a w . Statistically significant differences occurred when aw was reduced to the value of <0.97. The impact of a w on the Enterococcus faecium PCM 1859 thermoresistance was characterised by the following coefficients: z aw = 0.14−0.28, z′ aw = 0.18−0.44.
  PubDate: 2013-06-01