Chemical composition and antioxidant activity of two strawberry cultivars

The macro- and micro-chemical composition, as well as antioxidant activity of two strawberry cultivars, Marmolada and Clery, were studied. Results showed a noticeable difference in the sugar, protein and pectin contents. Clery had 6.92% and Marmolada 4.93% of total sugar. Also, protein and pectin contents were higher in the Clery cultivar. No significant difference was observed in acidity, as well as in ash and cellulose content. Marmolada had a higher content of total phenolics and flavonoids (228.04 mg GAE /100 g FW and 136.01 mg RE/100 g FW, respectively ). The anthocyanins content in Marmolada (32.0 mg CGE/100 g FW) was slightly lower than in Clery (36.0 mg CGE/100 g FW). The antioxidant activity was evaluated spectrophotometrically, using 2,2-diphenyl- 1-picrylhydrazyl (DPPH) radical scavenging activity assay. The DPPH free radical scavenging activity, expressed as EC50 value, of Marmolada (0.77 mg/ml )was higher than of Clery (0.83 mg/ml). There was a significant positive correlation (R2>0.90) between the concentration of phenolics/flavonoids/anthocyanins and DPPH radical scavenging activity of both strawberry cultivars. These results also showed that the antioxidant value of 100 g FW Marmolada and Clery is equivalent to 237.91 mg and 219.01 mg of vitamin C, respectively

Chemical composition and antioxidant activity of berry fruits

The main chemical composition, contents of total phenolic (TPh), total flavonoid (TF), and total monomeric anthocyianin (TMA), as well as the antioxidant activity of two raspberry cultivars (Meeker and Willamette), two blackberry cultivars (Čačanska bestrna and Thornfree) and wild bilberry were studied. The raspberry cultivars had the highest total solids among fruits investigated. Bilberry fruits had the highest sugar-to-acid ratio. Blackberry fruits were richer in crude fibers (cellulose) in comparison to raspberry and bilberry fruits. The content of pectic substances was highest in the bilberry. Also, bilberry had a highest content of TPh (808.12 mg GAE/100 g FW), TF (716.31 mg RE/100 g FW) and TMA (447.83 mg CGE/100 g FW). The antioxidant activity was evaluated spectrophotometrically, using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay. The DPPH free radical scavenging activity, expressed as the EC50 value (in mg of fresh weight of berry fruit per ml of the reaction mixture), of bilberry (0.3157 ± 0.0145 mg/ml) was the highest. These results also showed that the antioxidant value of 100 g FW bilberry, raspberry - Willamette, raspberry - Meeker, blackberry - Čačanska bestrna and blackberry - Thornfree is equivalent to 576.50 mg, 282.74 mg, 191.58 mg, 222.28 mg and 272.01 mg of vitamin C, respectively. There was a significant positive correlation between the antioxidant activities and content of total phenolics (RTPh 2=0.9627), flavonoids (RTF 2=0.9598) and anthocyanins (RTMA 2=0.9496) in berry fruits. [Projekat Ministarstva nauke Republike Srbije, br. TR 31044

Mineral and volatile composition of agua-mel from Portugal

Agua-mel (honey-water) is a typical honey-based product produced by the Portuguese beekeepers, particularly in southern Portugal. Agua-mel was characterized by mineral content and volatiles contents. Mineral content evaluation was performed based on a random sampling of 14 samples from a total of 16 samples provided by local producers. Mineral content showed that potassium predominated in agua-mel samples (1270-4105 mg/kg). The concentration of aluminium in one sample was tenfold higher (5.8 mg/kg) than in the remaining samples (0.3-0.6 mg/kg). Agua-mel volatiles were isolated by hydrodistillation and analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) from a subset of eight samples. Cluster analysis showed two poorly correlated clusters (S (corr) < 0.3). Cluster I only sample was dominated by trans-beta-ocimene (19 %), gamma-terpinene (15 %) and 2-furfural (9 %). Cluster II that included the remaining seven samples showed two moderately correlated subclusters (S (corr) < 0.5). The six samples with high correlation from subcluster IIa were dominated by 2-furfural (18-41 %) and benzene acetaldehyde (12-39 %). n-Nonadecane (14 %), n-heneicosane and 2-furfural (both 13 %) were the main components of subcluster IIb sample. Although the presence of some volatile compounds can help in the correlation between agua-mel and honey botanical source, the final product varies largely according to the preparation process even for the same producer, in different years. Agua-mel detailed characterization may assist in bringing added value to this typical Portuguese honey-based product

Antioxidant activity of white grape seed extracts on DPPH radicals

Composition and antioxidant activity of grape seed extract (GSE) obtained from red grape varietes are very well documented, in contrast to the white varietes. This paper presents the results of polyphenols content of ethyl acetate extract of grape seeds, obtained from two white grape varieties, Italian Riesling and Župljanka, and their antioxidant activity on the stable DPPH radical. The influence of the addition of GSE to raspberry juice on the DPPH radical was also examined. Content of total polyphenols in GSEs ranged between 81.6 and 82.8% (w/w), and the contetn of flavan-3-ols between 66.2 and 91.0% (w/w). HPLC results showed that the most abundant components in the extract were (+)-catechin and (-)-epicatechin for both grape varieties. All tested GSEs exhibited good antioxidant activity. IC50 values for the GSEs of Italian Riesling and Župljanka were 0.79 and 0.95 mg sample/mg DPPH radical, respectivelly. Since the GSE of Italian Riesling possesed stronger antioxidant activity, it was used for further experiments. The IC50 value for raspberry juice was 4.18 mg raspberry juice/mg DPPH. The raspberry juice with addition of 0.60 μg/mL of GSE showed antioxidant activity of 39.2%. The same juice with the threefold concentration of vitamin C (1.81 μg/ml) exhibited similar antioxidant activity (33.9%). Antioxidant activity of the same amount of juice without added antioxidants was lower (15.7%). The results showed that the GSE of white varietes could be considered as a good functional food ingredient

Bioactive compounds and antioxidant properties of dried apricot

Dried apricot was extracted using two different solvents: 80% ethanol and hexane. The contents of total phenolics, flavonoids and anthocyanins were determined in ethanol apricot extract (EAE), while the carotenoid content was determined in hexane apricot extracts (HAE) by spectrophotometric method. The detected amounts of bioactive compounds in dried apricot were: phenolics 498.13 ± 12.04 mg GAE/100g DA, flavonoids 218.45 ± 14.14 mg R/100g DA and anthocyanins 3.08 ± 0.40 mg CGE/100g DA. In dried apricot the β-carotene was present in the amount of 0.56 ± 0.03 mg/100g DA. Some individual phenolic compounds in EAE were determined by HPLC analysis and the most dominant compound was gallic acid (35.02 ± 1.65 mg/100g DA). Free radical scavenging activities of EAE and HAE were tested spectrophotometrically using stable DPPH radicals and reducing power method. The EC50 value for EAE was 2.05 ± 0.06 mg/ml and for HAE was 6.28 ± 0.01 mg/ml. The RP0.5 values determined by reducing power method were 6.11 ± 0.01 mg/ml for EAE and 62.04 ± 0.03 mg/ml for HAE. The results indicate that dried apricot can be a valuable source of natural antioxidants and can be used as a functional food ingredient in the food industry

Polyfloral, linden and acacia honeys with dried cherries after three months of storage - antioxidant and sensory evaluation

Samples of three types of honey: polyfloral (PH), linden (LH) and acacia (AH,) without and with addition of dried cherries (40%) were analyzed before and after three months of storage. The total phenol (TPh), flavonoid (TFd) and anthocyanin (TAn) contents, antioxidant activities and sensory properties of honeys with and without the addition of dry cherries were evaluated. TPh and TFd increased with addition of dried cherries to the honey, while enriched honeys showed high TAn. The LH sample with dried cherries showed the highest anthocyanins content (41.41mgCGE/100g). The antioxidant activity increased with addition of dried cherries in honey in the DPPH• test and reducing power. The PH and enriched PH exibited the best antiradical activity compared to LH and AH. The EC50 DPPH values were: 23.81 for PH and 24.19 mg/mL for PH, while the EC50 DPPH were: 1.16 mg/mL for PH40 and 1.18 mg/mL for PH40s. RP0.5 values were: 57.00 mg/mL for PH40 and 56.00 mg/ml for PH40s, while RP0.5 were: 15.05 mg/mL for PH40 and 15.18 mg/mL for PH40s. The statistical analysis showed that TPh, TFd and TAn, and antioxidant activity of honeys and enriched honeys showed significant correlation. Sensory analysis of honey with dried cherries, before and after storage, indicated very good sensory characteristics

Extraction and encapuslation of bioactive compounds from carrots

Carrot is an important root vegetable rich in bioactive compounds like carotenoids and polyphenols with appreciable levels of several other functional components having significant health-promoting properties. Utilization of carotenoids is limited due to their instability. Encapsulation is one of the alternatives used to improve carotenoid stability. The objectives of this study were to optimize the extraction and encapsulation of carotenoids from carrot. Freeze-dried carrots were extracted by conventional solvent extraction (CSE) using four solvents, i.e. ethanol, acetone, ethyl acetate, and hexane. Although CSE using hexane and ethyl acetate resulted in highest carotenoid contents (18.27 and 15.73 mg β-carotene/100 g), acetone and ethanol at a solid to solvent ratio 1:10 w/v with slightly lower carotenoid contents (14.52 and 11.45 mg β-carotene/100 g) were chosen for further studies due to their higher food compatibility and higher polyphenol content (88.86 and 66.21 mg GAE/100 g) than with lower solid to solvent ratio (1:5 w/v). Ethanol and acetone carrot extracts were encapsulated using different carriers by a freeze-drying method in order to obtain the optimum encapsulate with the highest carotenoid encapsulation efficiency (EE). Encapsulation using the maltodextrin, whey and soy protein as a wall material yielded an EE of carotenoids ranging from 41.95% to 100%. The encapsulated β-carotene content was evaluated during two months of storage at ambient temperature under light and dark conditions. Generally, the retention of carotenoids was significantly higher in dark conditions, where maximum retention (65.94-87.32%) occurred in the samples encapsulated in maltodextrin and soy protein. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31044

Optimization of the bioactive compounds content in raspberry during freeze-drying using response surface method

The production of high-quality freeze-dried raspberry was studied by response surface method. Two independent variables, temperature (X1) and time (X2) were determined as the most important factors affecting the final product quality estimated by the responses: total phenol (Y1), total anthocyanin (Y2), vitamin C (Y3) and total bioactive compounds (Y4) content. A two-factor central composite design was used for freeze-drying experiments. The second order polynomial models obtained were found to be significant (p<0.05) for all responses. The statistical analysis of experimental data indicated that only quadratic time variable (X22) had significant (p<0.05) effect on all responses. The optimal conditions for all responses combined were found to be: -31 ºC and 35 h. The experimental values of all responses obtained under optimal conditions were in good agreement with predicted values which enables the use of the proposed mathematical models for optimization of investigated process. [Projekat Ministarstav nauke Republike Srbije, br. TR31044

Antioxidant activity of three different Serbian floral honeys

In this study, three Serbian honey samples (Acacia, Linden and "Homoljski med") were analyzed to determine their total phenolic, flavonoid and antioxidant content, as well as their in vitro antioxidant activity. The antioxidant activity of honeys was examined by different tests, including the reducing power and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. In addition, correlations between the antioxidant activity and total phenolic, as well as flavonoid content were also sought. The highest content of total phenolics (27.44 mg/100 g), flavonoids (9.78 mg/100 g), reducing power and DPPH free radical scavenging activity were obtained in the case of Linden honey. The EC50 values of the Linden honey, determined based on the reducing power and DPPH radical scavenging activity, were 24.17 mg/ml and 51.34 mg/ml, respectively. Also, the antioxidant content was highest for Linden honey, and it valued 5.45 mg QEAC/100 g (expressed as mg of quercetin equivalent antioxidant content - QEAC per 100 g of honey) and 7.82 mg AEAC/100 g (expressed as mg of ascorbic acid equivalent antioxidant content - AEAC per 100 g of honey). Also, a linear correlation was observed between the antioxidant activity and total phenolics, as well as total flavonoids