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The aim of this study was to compare efficiency of RP-HPLC (Reversed-Phase High-Performance Liquid Chromatography) and LOC (Lab-on-Chip) methods for wheat gluten protein quantification regarding clustering of wheat cultivars according to the genetic similarity (HMW-GS combinations), as well as to explore relations of these two methods to wheat quality parameters. For that purpose, wheat quality parameters (protein content, falling number, wet gluten content, gluten index, Farinograph, Extensograph, and Amylograph), as well as amounts of gliadin and glutenin fractions by RP-HPLC and LOC methods were determined in two different sets of wheat cultivars (Croatian and Serbian). The percentages of gluten proteins and the values of quality parameters were used to characterize the samples by principal component analysis (PCA). Gluten protein quantification performed by method based on the protein fraction separation by molecular weights (LOC) was better for grouping of genetically similar wheat cultivars than quantification of proteins separated by their different solubility in specified solvent gradient (RP-HPLC). LOC method showed higher potential in wheat quality prediction.

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Modifiedß-casein forms were prepared with acid/alkaline phosphatase. The choice between acid and alkaline phosphatases was critical for the physico-chemical properties ofß-casein. Removal of phosphoryl groups fromß-casein via alkaline phosphatase increased the retention time measured using RP-HPLC and did not change the second-derivative UV spectra. Moreover, the pI value shifted to neutral pH and the solubility decreased, especially at the alkaline pH range.ß-Casein modified enzymatically via alkaline phosphatase formed a foam with volume and stability similar to that formed with intact one. In turn, a dramatic decrease in foam stability was found forß-casein modified via acid phosphatase. Chromatographic, spectral and electrophoretic results suggest proteolytic acivity of acid phosphatase preparation.

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Acta Alimentaria
Authors: D. Giuffrida, M. Ziino, A. Verzera, C. Condurso, and V. Romeo

The biogenic amine content of “Provola dei Nebrodi”, a typical “pasta filata” Sicilian cheese, was studied at different ripening stages. Reversed-phase high performance liquid chromatography (RP-HPLC) with fluorimetric detection was employed for the identification and quantification of eight different amines: ethanolamine, histamine, serotonine, tyramine, tryptamine, 2-phenylethylamine, putrescine and cadaverine. Histamine was the most representative amine in all the analysed cheese samples, followed by serotonin and tyramine. The total amount of biogenic amines was lower than 0.1 ppm in fresh samples, whereas it reached 33.57 ppm in samples with the longest ripening time. The biogenic amine contents were correlated with the proteolytic maturation coefficient, defined as the water-soluble nitrogen/total nitrogen (WSN/TN %) percent ratio. The results showed amine contents lower than the toxic level even for samples with the longest ripening time.

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Organic acids, total phenolic compounds, and antioxidant activity were determined in two different juices of gilaburu fruits ( Viburnum opulus L., belonging to the Caprifoliaceae family). Organic acids, analysed by RP-HPLC-UV visible detection, were individually detected and quantified. The predominant organic acid of samples was L-malic acid. The mean concentration of total phenolic compounds of fresh gilaburu juice (FGJ) and pasteurised gilaburu juice (PGJ) was 351.26 and 330.40 mg gallic acid equivalents (GAE)/100 ml, respectively. Average EC 50 values (in the DPPH• test) were 25.06 μl mg −1 DPPH• for FGJ, and 30.87 μl mg −1 DPPH• for PGJ. Total phenolic compounds of both juices were higher than those of some commonly consumed juices and nectars.

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's quantitation by RP-HPLC .” American-Eurasian J Sci Res , vol. 8 , pp. 63 – 67 , 2013 . [11] I. O. Igwe and A. A. Ejim , “ Studies on mechanical and end-use properties of natural rubber filled with snail shell powder ,” Mater. Sci. Appl. , vol. 2

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Gluten proteins composed of gliadins and glutenins are important contributors to the wheat quality properties. Twenty-eight winter wheat cultivars differing in bread processing quality were collected at the experimental fields of the Agricultural Institute Osijek, Croatia, in growing season 2006/2007.The HMW-GS composition and gliadin contents were determined by SDS-PAGE and RP-HPLC, respectively, with the aim to determine their relationship with wheat quality properties. Based on gliadins and HMW-GS data for 28 wheat cultivars PLS models were developed for the prediction of 15 baking quality parameters.NIPALS algorithm was applied for the evaluation of the latent variables and regression coefficient parameters. The obtained 4-th order models have average coefficients of determination R2=0.80.Determined variable importance in projections (VIP) coefficients revealed that HMW-GS data have the dominant influence on the baking quality parameters. For extensographic and farinographic properties the Glu-D1 locus has the main VIP coefficient while Glu-B1 locus is the most important for the indirect quality parameters. The derived PLS models and VIP coefficients could be used in molecular based wheat selection and breeding program.

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The procedure involving water and water-methanol extraction, RP-HPLC-C18 column chromatography with PDA detection was developed for determination of cinnamic acid and benzoic acid derivatives in grapevine’s dietary supplements (LV, RW, VIN, VIC, and DK) available on the Polish market. Phenolic acids were analysed before and after acidic and basic hydrolysis and identified against standards. Totalamount of studied phenolic acids determined by HPLC-PDA was compared with total polyphenols content (TPC) by Folin-Ciocalteu method. The average content of studied phenolic acids (70.54±0.21; 122.95±0.49; 87.67±0.10; 132.21±0.24; 266.78 ±0.39, and 18.16±0.09 mg/100 g d.m. (dry mass) for LV, RW, VIN, VIC, DK, and WW, respectively) were higher than the TPC (1489.91±0.39, 1648.19±0.14, 1574.38±0.33, 1643.64±0.12, 1984.75±0.97, and 715.55±0.36 mg/100 g d.m. for LV, RW, VIN, VIC, DK, and WW, respectively). The new developed method was validated for specifi city, repeatability, and accuracy and can be suitable for routine quality and quantity analysis of dietary supplements containing grape vine (Vitis vinifera).

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This study assessed the rheological behaviour, physical stability, and the phenolic compounds of Eugenia pyriformis Cambess. (uvaia) and Eugenia uniflora L. (pitanga) fruits. The effect of temperature on the rheological behaviour of the fruit was evaluated (10–60 °C) by means of non-oscillatory rheological analysis in a rheometer. The whole samples (purée) exhibited shear-thinning behaviour (n<1), whereas the centrifuged samples exhibited Newtonian behaviour (n=1). The Arrhenius equation accurately described the effect of temperature on the apparent viscosity of the fruit. The stability study was performed by means of sedimentation and turbidity testing. The stabilisation of purées occurred on the second (Eugenia pyriformis Cambess.) and on the third (Eugenia uniflora L.) day of storage. The results demonstrated that turbidity increased with an increase in homogenization velocity. The phenolic compounds of the fruit were identified and quantified by reverse-phase high-performance liquid chromatography (RP-HPLC). The samples presented significant differences in the concentration of phenolic compounds. Among the phenolic acids identified, gallic acid was the one with higher concentration in both fruit assayed. Comparing the fruits, it was observed that Eugenia pyriformis presented higher content of flavonoids (5-fold) and Eugenia uniflora presented higher content of phenolic acids (8.5-fold), especially gallic acid. Myricetin and quercetin were the main flavonoids determined in Eugenia pyriformis.

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The content of potentially antioxidant, anticarcinogenic and antiallergic flavonoid aglycons, quercetin, kaempferol, myricetin, apigenin and luteolin of 45 fruits were determined by RP-HPLC with UV detection. Fresh and dried fruits were purchased in the local markets in Budapest at a period of their most frequent consumption. Total flavonoid content of fruits varied between 0–1000 mg kg –1, the average concentration was about 30 mg kg –1 fresh weight. Quercetin could be detected in most fruits, namely in apples, pear, plums, sweet and sour cherry and berries between 10–53 mg kg –1. Luteolin at a concentration of 20 mg kg –1 was found in melons, apples, kiwi and lemon. Myricetin was in detectable amount in redcurrant, and at very high concentration in some berry fruits (mulberry 453 mg kg –1, raspberry 540 mg kg –1, blackberry 636 mg kg –1, strawberry 994 mg kg –1), and in walnut (4565 mg kg –1). Kaempferol and apigenin were not found in the fruits investigated. None of the five flavonoids was found in some variety of grapes, in peach, pear, banana, orange, grapefruit and tangerine, in nuts such as almond, pistachio, nuts, and in dried fruits such as raisin, date, fig and prunes. These data provide a basis for the evaluation of the average daily intake of Hungarian population and for an epidemiological evaluation of health-promoting effects of flavonoids. __

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The content of the potentially health-defensive and disease-preventive flavonoids quercetin, kaempferol, myricetin, apigenin and luteolin of 31 vegetables were determined by RP- HPLC with UV detection. Vegetables were purchased at the local markets in Budapest at a period of their most frequent consumption. Quercetin levels in the edible parts of most vegetables were generally below 10 mg kg &1, except for onions (67&121.5 mg kg &1), lettuce (13.5&35.0 mg kg &1), dill (74.5 mg kg &1), broccoli (15.5 mg kg &1) and spinach (272.2 mg kg &1). Kaempferol was below 30 mg kg &1 except for parsnip (66.4 mg kg &1) and leek (45.8 mg kg &1). Myricetin could only be detected in lettuce, Swedish turnip, parsley and celery leaves, and dill. Detectable amount of luteolin was in radishes, some representatives of Brassica, sweet peppers, celery leaves and spinach while apigenin was only in Swedish turnip, celery root and celery leaves. These data provide a basis for the evaluation of the average daily intake of Hungarian population and for an epidemiological evaluation of health-promoting effects of flavonoids.

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