Search Results

You are looking at 11 - 20 of 68 items for :

  • Materials and Applied Sciences x
  • Refine by Access: All Content x
Clear All

In this study, the antibacterial and antioxidant activities of dried fruit extract of cranberry (gilaburu, Viburnum opulus) were determined. The total phenolic content was found to be 131.99±2.11 mg gallic acid equivalent (GAE) g-1 in the cranberry fruit extract (CFE). The antioxidant activity of the extract was found to be 315.50±8.2 mg g-1 in dried methanol extract. At 2, 5, 10 and 15% concentrations the extracts were tested for their antibacterial effects by using the agar diffusion method against ten bacteria, some of them pathogenic and some of them spoilage microorganisms. All bacteria were inhibited by 10 and 15% concentrations of the CFE. Methanol (control) had no inhibitory effect on all the tested bacteria. The most sensitive of the bacteria was A. hydrophila, whereas the most resistant bacterium was Y. enterocolitica.

Restricted access

Antioxidant and free radical scavenging activities of the extracts of sumac (Rhus coriaria) fruits and cassia (Cinnamomum cassia) cortex were studied. Plant samples were extracted with methanol:water (80:20) and an aliquot of each extract was fractionated using n-hexane and ethyl acetate. Antioxidant activities of n-hexane, ethyl acetate and water fractions were measured using Fe+2 induced linoleic acid-TBA-peroxidation reaction and the Rancimat methods. Free radical scavenging activities of the fractions were determined on 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Results were compared with those for butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT). The ethyl acetate fraction of plant materials exhibited a marked antiradical activity on DPPH.

Restricted access

Superficial scald is a postharvest physiological disorder of apples characterized by browning of apple skin during prolonged storage. It has been hypothesized that conjugated triene hydroperoxides (CTH) attack cell membranes causing membrane perturbation and the manifestation of the disorder. The purpose of this study was to compare the common synthetic antioxidant diphenylamine (DPA) treatment with postharvest vapour treatments for superficial scald prevention. Apples cv. ‚Granny Smith™ were treated with ethanol, methanol and »apple aroma« vapours. The influence of these treatments on scald susceptibility and sensorial quality of apples was examined. The ethanol treatments were effective in superficial scald prevention but they caused a high incidence of internal browning after two months of storage. The 10 day treatments at 20 °C developed very pronounced internal browning after storage. The aroma treatment was the least effective in apple scald prevention but no internal disorders appeared after storage. Apples treated with methanol at 20 °C retain a great deal of their initial green colour. Vapour treatments demonstrated to be potential methods for scald prevention. Additional research is needed to minimise the internal disorders of treated fruit.

Restricted access

The objective of this study was to examine antibacterial, antifungal and antiviral properties of selected Phlomis species (Lamiaceae) growing in Turkey. The petroleum ether and methanol extracts of the seven species, namely P. armeniaca Willd., P. bourgaei Boiss., P. leucophracta P.H. Davis & Hub.-Mor., P. lunariifolia Sibth. & Sm., P. lycia D. Don, P. pungens Willd. var. pungens , and P. pungens var. hirta Velen. were tested against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus, Bacillus subtilis , and Enterococcus faecalis for their antibacterial activity using ampicillin and oflaxocin as references. Antifungal activity of the same extracts was determined against Candida albicans using microdilution method with ketocanazole as reference. Both DNA virus Herpes simplex type-1 (HSV-1) and RNA virus Parainfluenza (PI-3) were employed for antiviral assessment of the Phlomis extracts using Madin-Darby Bovine Kidney and Vero cell lines in which acyclovir for HSV-1 and oseltamivir for PI-3 were employed as reference drugs. Although both the petroleum ether and methanol extracts seemed to exert similar antibacterial activity, the methanolic extracts were observed to be more active against S. aureus and E. faecalis . On the other hand, methanolic extract of P. pungens var. pungens possessed notable antiviral activity against both type of viruses.

Restricted access

Pigments, such as carotenes, xanthophylls and chlorophylls, were extracted from both vegetables and their industrial products by using a 2:1 (v/v) dichloromethane/methanol solution. To separate and quantify the components in the extraction mixture, a HPLC analysis on reversed phase C30 column and binary gradient, made of methanol/water solution and dichloromethane, was employed. This gradient appears to have some advantages over other reported methods, which utilize reversed phase C30 column, in terms of resolution and analysis time. The linearity range of the detection response, the chromatographic resolution of a standard mixture constituted of lutein, zeaxanthin, trans-ß-apo-8?-carotenal, ß-cryptoxanthin, chlorophyll-b, ?-carotene, chlorophyll-a, ?-carotene, lycopene and the conditions for the complete extraction of those substances from the vegetable matrix were investigated. Both retention time and peak area reproducibility showed an average variation coefficient of about 2% for all the analyzed compounds. As a consequence of the good chromatographic separation of chlorophylls from carotenoids, sample saponification was found unnecessary when analyzing green vegetable products. Finally, to illustrate the applicability of the method, the presence of carotenoid esters in tomato and orange products was examined.

Restricted access

Changes of volatile compounds of noni juice during the traditional process of fermentation/aging was studied by means of HS-SPME and GC-MS. Major acids, octanoic and hexanoic, diminished their concentration; while esters of ethanol, 1-butanol and 1-hexanol, with their flavour fruity notes, increased. The concentration of esters of methanol and 3-methyl-3-buten-1-ol decreased during the fermentation/aging process, whereas major alcohols of noni juice, 1-hexanol and 1-octanol, increased their concentration during the process. During the 60 days of the process the volatile composition of the noni juice had reached stability. These chemical changes justify that fermented juice possesses a flavour less pungent than fresh juice due to an important decrease in the hexanoic and octanoic contents, as well as a greater fruity note due to the increment in ester concentrations.

Restricted access
Acta Alimentaria
Authors: V. Bušić, S. Kovač, D. Gašo-Sokač, and H. Lepeduš

The aim of this study was to examine antioxidant activities of the anthocyanins isolated from different sour cherry ( Prunus cerasus ) cultivars. DPPH radical method and photochemiluminescence detection method were employed. The effect of isolated anthocyanins on peroxidase activity was also investigated. In the DPPH method, methanol extract of isolated anthocyanins was employed and results showed the highest radical-scavenging activity of anthocyanins isolated from one genotype of Cigančica cherry (genotype VN 10–11), Petrovaradinska and Oblačinska cherry cultivar. Integral antioxidative capacity was determined by luminometry (Photochem), calculating the ascorbic acid equivalents. The best reducing power was shown by anthocyanins isolated from Maraska and Petrovaradinska cherry cultivars. Peroxidase activity of fresh plant material was determined and the influence of anthocyanins on peroxidase activity was investigated.

Restricted access
Acta Alimentaria
Authors: J. Bystricka, J. Musilova, J. Tomas, J. Noskovic, E. Dadákova, and P. Kavalcova

Onion bulbs (Allium cepa L.) are good sources of flavonoids. The aim of this study was to analyse the changes in dynamics of quercetin formation in three varieties of onions (white, yellow, and red) during the vegetation period. Quercetin content was determined after acid hydrolysis (1.2 M HCl in 50% aqueous methanol) by high-performance liquid chromatography (HPLC). The content of total phenolics was determined using Folin-Ciocalteu reagent (FCR) according to LACHMAN and co-workers (2003). The content of polyphenols in onion ranged from 2893 to 6052 mg kg–1 and the content of quercetin ranged from 52.44 to 280.72 mg kg–1 in fresh matter. The highest content of polyphenols and quercetin was found in the red variety. According to statistical analysis the dynamic of quercetin formation in all cultivars had statistically moderate (P<0.05) increasing tendency. Increasing content of polyphenols was accompanied with slight increase of quercetin, but the differences remained insignificant (P<0.05).

Restricted access

The antioxidant effects of seafennel (Crithmum maritimum L.) essential oil and rose (Rosa canina) methanol extract at different concentrations were tested in natural olive oil stored at 60 °C, by measuring peroxide values and free oil acidity after regular intervals. All concentrations of both plant extracts showed antioxidant effect compared with control in experiments. The most effective extracts were 0.4% level of rose. The 0.2% concentrations of rose extract and seafennel oil and 0.4% level of seafennel oil followed in a decreasing order, respectively. The 0.2% level of seafennel oil in olive oil had more effect than those of only 0.02% concentrations of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). Acidity values of seafennel oil at the 0.4% concentration were high compared with its 0.2% level. Acidity values of both rose concentrations were found partly similar.

Restricted access

The present research is on the study of lycopene extraction from different raw and processed tomatoes, using traditional extraction methods with several solvents. The influences of the temperature and the light exposure were taken into consideration. The best extraction lycopene levels were obtained when chloroform:methanol mixture was used as solvent, followed by the hexane:acetone mixture and ethanol 95%. The lycopene is better extracted at room temperature compared with refrigeration and freezing temperatures. Lyophilized tomatoes contained the highest amount of lycopene (14.11 mg/100 g), followed by dried tomatoes with 6.01 mg/100 g, tomato juice with 11.38 mg/100 g, and the fresh tomatoes with 4.13 mg/100 g.

Restricted access