An approach towards rapid optical measurements of antioxidant activity in blueberry cultivars

Blueberries are well known for their high antioxidant levels. Compared to bilberries (V. myrtillus) with higher antioxidant activity and more intensive blue colour throughout the whole berry, highbush blueberries have the blue pigments concentrated in the skin. Highbush blueberry skin is found to contain a very high content of phenolic compounds. To measure the total antioxidant activity in blueberries, several methods, mostly destructive, including the FRAP assay, have been used. This work is an initial approach towards a simple and rapid method, combining optical and antioxidant activity measurements. Highbush blueberry (V. corymbosum) cultivars ‘Bluecrop’, ‘Hardyblue’, ‘Patriot’, and lowbush cultivars ‘Putte’ (a hybrid originated from V. angustifolium) and ‘Aron’ (V. corymbosum x V. uliginosum) were grown at the Norwegian University of Life Sciences (59º 40’N). Berries were harvested at commercial blue-ripe stage of maturity. Fresh berries were cut horizontally and placed on a scanner in order to examine berry size and skin thickness. Berries were weighed, and analysed for antioxidant activity using the FRAP (Ferric Reducing Ability of Plasma) assay. The FRAP assay is a non-specific method based on absorption changes following a reduction of a ferric- to a ferrous-complex in the presence of antioxidants.Own previous results have shown that antioxidant activity and berry weight varied between cultivars (REMBERG et al., 2003). Small berries had higher antioxidant activity compared to larger berries. In this follow-up project, skin thickness and berry diameter were measured by using an image- processing program. Berry and skin cross-section areas were correlated with the antioxidant activity

Exploring Chromophore-Binding Pocket: High-Resolution Solid-State 1H–13C Interfacial Correlation NMR Spectra with Windowed PMLG Scheme

High-resolution two-dimensional (2D) 1H–13C heteronuclear correlation spectra are recorded for selective observation of interfacial 3–5.5 Å contacts of the uniformly 13C-labeled phycocyanobilin (PCB) chromophore with its unlabeled binding pocket. The experiment is based on a medium- and long-distance heteronuclear correlation (MELODI–HETCOR) method. For improving 1H spectral resolution, a windowed phase-modulated Lee–Goldburg (wPMLG) decoupling scheme is applied during the t1 evolution period. Our approach allows for identification of chromophore–protein interactions, in particular for elucidation of the hydrogen-bonding networks and charge distributions within the chromophore-binding pocket. The resulting pulse sequence is tested on the cyanobacterial (Cph1) phytochrome sensory module (residues 1–514, Cph1Δ2) containing uniformly 13C- and 15N-labeled PCB chromophore (u-[13C,15N]-PCB-Cph1Δ2) at 17.6 T

Physio-chemical, mineral composition and antioxidant properties of roselle (hibiscus sabdariffa l.) Extract blended with tropical fruit juice

African journal of food, agriculture, nutrition and development, 2014; 14 (3): 8963-8978.Different varieties of fruit juices and beverages are available globally and there has been an increased consumption of fruit juices and beverages due to consumer awareness of nutritional and health benefits. Juice extracts are produced from various parts of plants including leaves, fruits and flowers. Hibiscus sabdiriffa (Roselle) is one such plant whose flowers are used to prepare juices. The roselle extract has a unique red colour, good flavour, low sugar and high acidic content. The acidity makes the juice sour hence the need for addition of sweetening products. A study was conducted on the formulation of roselle extract-tropical fruit blends aimed at establishing its physiochemical, mineral and antioxidant composition. Dried roselle calyces at a ratio of 1:10 (dried roselle calyces: water) were extracted at 50oC for 30 minutes. The roselle extracts were blended at various proportions of fruit (mango, papaya and guava) juices. Physiochemical, mineral composition and antioxidant properties were evaluated in all the roselle fruit juice blends The results for all rosellefruit blends (80% roselle to 20% roselle) showed that pH ranged between (2.35-3.32), total soluble solids (5.6-10.6o Brix), titratable acidity (1.28-1.92 %), reducing sugars (2.95-5.55) mg/100g,. Calcium (555.3-23.4 mg/100g DM), Magnesium (213.8-11.5 mg/100g DM), Phosphorus (39.8-9.0 mg/100g DM), Sodium (2.3-5.47 mg/100g DM), Zinc (5.85-0.69 mg/100g DM), Iron (29.5-1.36 mg/100g DM), monomeric anthocyanin (493.5-118.2 mg cyanidin-3-glucoside/100g), vitamin C (40.0-86.5 mg/100g), total phenol (54.6-10.8 mg gallic acid/ 100 g) and antioxidant activity (1.80-1.37 mmol/L). Blending of tropical fruit juices with roselle extract have improved mineral composition and antioxidant properties of fruit juices as roselle is a good source of calcium, magnesium and iron. Antioxidants acts as free radical scavengers inhibit lipid peroxidation and other free radical mediated process, therefore, consumption of roselle-fruit juices with high anthocyanin will protect human body from several diseases attributed to the reactions of free radicals

Influence of storage temperature and time on the physicochemical and bioactive properties of roselle-fruit juice blends in plastic bottle

Food Science & Nutrition 2014; 2(2): 181– 191Roselle-fruit juice blends were made from roselle extract and mango, papaya, and guava juices at the ratio of 80:20, 60:40, 40:60, and 20:80, % roselle: fruit juice, respectively. The blends were pasteurized at 82.5°C for 20 min and stored in 100 mL plastic bottles at 28 and 4°C for 6 months. The effects of storage time and temperature on physicochemical and bioactive properties were evaluated. Total soluble solids, pH, and reducing sugars increased significantly (P < 0.05) in some blends while titratable acidity decrease with increasing storage time. Vitamin C, total monomeric anthocyanins (TMA), total phenols (TPC), and antioxidant activity (ferric reducing ability of plasma, FRAP) in all roselle-fruit blends (40% roselle) decreased significantly (P < 0.05) at 28 and 4°C as storage progressed. Vitamin C in all roselle-fruit blends (40% roselle) decreased from 58–55% to 43–42% when stored at 28 and 4°C, respectively. TMA losses were 86–65% at 28°C and 75–53% at 4°C while TPC losses were 66–58% at 28°C and 51–22% at 4°C. Loss of antioxidant capacity (FRAP) was 18–46% at 28°C and 17–35% at 4°C. A principal component analysis (PCA) differentiated roselle- juice fruit blends into two clusters with two principle components PC1 and PC2, which explained 97 and 3% (blends stored at ambient temperature) and 96 and 4% (blends stored at refrigerated temperature) of the variation, respectively. PC1 differentiated roselle-guava juice blends which were characterized by vitamin C, TPC, FRAP, and pH, while PC2 from another cluster of roselle-mango and roselle-papaya juice blends and was characterized by TSS, RS, and color parameters (L* a* b*). However, TMA was the main variable with the highest effect on all roselle-fruit juice blends regardless of the storage time and temperature

Physio-chemical, mineral composition and antioxidant properties of roselle (hibiscus sabdariffa l.) Extract blended with tropical fruit juice

African journal of food, agriculture, nutrition and development, 2014; 14 (3): 8963-8978.Different varieties of fruit juices and beverages are available globally and there has been an increased consumption of fruit juices and beverages due to consumer awareness of nutritional and health benefits. Juice extracts are produced from various parts of plants including leaves, fruits and flowers. Hibiscus sabdiriffa (Roselle) is one such plant whose flowers are used to prepare juices. The roselle extract has a unique red colour, good flavour, low sugar and high acidic content. The acidity makes the juice sour hence the need for addition of sweetening products. A study was conducted on the formulation of roselle extract-tropical fruit blends aimed at establishing its physiochemical, mineral and antioxidant composition. Dried roselle calyces at a ratio of 1:10 (dried roselle calyces: water) were extracted at 50oC for 30 minutes. The roselle extracts were blended at various proportions of fruit (mango, papaya and guava) juices. Physiochemical, mineral composition and antioxidant properties were evaluated in all the roselle fruit juice blends The results for all rosellefruit blends (80% roselle to 20% roselle) showed that pH ranged between (2.35-3.32), total soluble solids (5.6-10.6o Brix), titratable acidity (1.28-1.92 %), reducing sugars (2.95-5.55) mg/100g,. Calcium (555.3-23.4 mg/100g DM), Magnesium (213.8-11.5 mg/100g DM), Phosphorus (39.8-9.0 mg/100g DM), Sodium (2.3-5.47 mg/100g DM), Zinc (5.85-0.69 mg/100g DM), Iron (29.5-1.36 mg/100g DM), monomeric anthocyanin (493.5-118.2 mg cyanidin-3-glucoside/100g), vitamin C (40.0-86.5 mg/100g), total phenol (54.6-10.8 mg gallic acid/ 100 g) and antioxidant activity (1.80-1.37 mmol/L). Blending of tropical fruit juices with roselle extract have improved mineral composition and antioxidant properties of fruit juices as roselle is a good source of calcium, magnesium and iron. Antioxidants acts as free radical scavengers inhibit lipid peroxidation and other free radical mediated process, therefore, consumption of roselle-fruit juices with high anthocyanin will protect human body from several diseases attributed to the reactions of free radicals

Influence of storage temperature and time on the physicochemical and bioactive properties of roselle-fruit juice blends in plastic bottle

Food Science & Nutrition 2014; 2(2): 181– 191Roselle-fruit juice blends were made from roselle extract and mango, papaya, and guava juices at the ratio of 80:20, 60:40, 40:60, and 20:80, % roselle: fruit juice, respectively. The blends were pasteurized at 82.5°C for 20 min and stored in 100 mL plastic bottles at 28 and 4°C for 6 months. The effects of storage time and temperature on physicochemical and bioactive properties were evaluated. Total soluble solids, pH, and reducing sugars increased significantly (P < 0.05) in some blends while titratable acidity decrease with increasing storage time. Vitamin C, total monomeric anthocyanins (TMA), total phenols (TPC), and antioxidant activity (ferric reducing ability of plasma, FRAP) in all roselle-fruit blends (40% roselle) decreased significantly (P < 0.05) at 28 and 4°C as storage progressed. Vitamin C in all roselle-fruit blends (40% roselle) decreased from 58–55% to 43–42% when stored at 28 and 4°C, respectively. TMA losses were 86–65% at 28°C and 75–53% at 4°C while TPC losses were 66–58% at 28°C and 51–22% at 4°C. Loss of antioxidant capacity (FRAP) was 18–46% at 28°C and 17–35% at 4°C. A principal component analysis (PCA) differentiated roselle- juice fruit blends into two clusters with two principle components PC1 and PC2, which explained 97 and 3% (blends stored at ambient temperature) and 96 and 4% (blends stored at refrigerated temperature) of the variation, respectively. PC1 differentiated roselle-guava juice blends which were characterized by vitamin C, TPC, FRAP, and pH, while PC2 from another cluster of roselle-mango and roselle-papaya juice blends and was characterized by TSS, RS, and color parameters (L* a* b*). However, TMA was the main variable with the highest effect on all roselle-fruit juice blends regardless of the storage time and temperature

PHYSIO-CHEMICAL, MINERAL COMPOSITION AND ANTIOXIDANT PROPERTIES OF ROSELLE (HIBISCUS SABDARIFFA L.) EXTRACT BLENDED WITH TROPICAL FRUIT JUICES

ABSTRACT Different varieties of fruit juices and beverages are available globally and there has been an increased consumption of fruit juices and beverages due to consumer awareness of nutritional and health benefits. Juice extracts are produced from various parts of plants including leaves, fruits and flowers. Hibiscus sabdiriffa (Roselle) is one such plant whose flowers are used to prepare juices. The roselle extract has a unique red colour, good flavour, low sugar and high acidic content. The acidity makes the juice sour hence the need for addition of sweetening products. A study was conducted on the formulation of roselle extract-tropical fruit blends aimed at establishing its physiochemical, mineral and antioxidant composition. Dried roselle calyces at a ratio of 1:10 (dried roselle calyces: water) were extracted at 50 o C for 30 minutes. The roselle extracts were blended at various proportions of fruit (mango, papaya and guava) juices. Physiochemical, mineral composition and antioxidant properties were evaluated in all the roselle fruit juice blends The results for all rosellefruit blends (80% roselle to 20% roselle) showed that pH ranged between (2.35-3.32), total soluble solids (5.6-10.6 o Brix), titratable acidity (1.28-1.92 %), reducing sugars (2.95-5.55) mg/100g,. Calcium (555.3-23.4 mg/100g DM), Magnesium (213.8-11.5 mg/100g DM), Phosphorus (39.8-9.0 mg/100g DM), Sodium (2.3-5.47 mg/100g DM), Zinc (5.85-0.69 mg/100g DM), Iron (29.5-1.36 mg/100g DM), monomeric anthocyanin (493.5-118.2 mg cyanidin-3-glucoside/100g), vitamin C (40.0-86.5 mg/100g), total phenol (54.6-10.8 mg gallic acid/ 100 g) and antioxidant activity (1.80-1.37 mmol/L). Blending of tropical fruit juices with roselle extract have improved mineral composition and antioxidant properties of fruit juices as roselle is a good source of calcium, magnesium and iron. Antioxidants acts as free radical scavengers inhibit lipid peroxidation and other free radical mediated process, therefore, consumption of roselle-fruit juices with high anthocyanin will protect human body from several diseases attributed to the reactions of free radicals

Eur. J. Biochem.

Two ORFs, cphA and cphB , encoding proteins CphA and CphB with strong similarities to plant phytochromes and to the cyanobacterial phytochrome Cph1 of Synechocystis sp. PCC 6803 have been identified in the filamentous cyanobacterium Calothrix sp. PCC7601. While CphA carries a cysteine within a highly conserved amino-acid sequence motif, to which the chromophore phytochromobilin is covalently bound in plant phytochromes, in CphB this position is changed into a leucine. Both ORFs are followed by rcpA and rcpB genes encoding response regulator proteins similar to those known from the bacterial two-component signal transduction. In Calothrix , all four genes are expressed under white light irradiation conditions, albeit in low amounts. For heterologous expression and convenient purification, the cloned genes were furnished with His-tag encoding sequences at their 3' end and expressed in Escherichia coli . The two recombinant apoproteins CphA and CphB bound the chromophore phycocyanobilin (PCB) in a covalent and a noncovalent manner, respectively, and underwent photochromic absorption changes reminiscent of the P-r and P-fr forms (red and far-red absorbing forms, respectively) of the plant phytochromes and Cph1. A red shift in the absorption maxima of the CphB/PCB complex (lambda(max) = 685 and 735 nm for P-r and P-fr , respectively) is indicative for a noncovalent incorporation of the chromophore (lambda(max) of P- r , P-fr of CphA: 663, 700 nm). A CphB mutant generated at the chromophore-binding position (Leu246-->Cys) bound the chromophore covalently and showed absorption spectra very similar to its paralog CphA, indicating the noncovalent binding to be the only cause for the unexpected absorption properties of CphB. The kinetics of the light-induced P-fr formation of the CphA-PCB chromoprotein, though similar to that of its ortholog from Synechocystis , showed differences in the kinetics of the P-fr formation. The kinetics were not influenced by ATP (probing for autophosphorylation) or by the response regulator. In contrast, the light-induced kinetics of the CphB-PCB complex was markedly different, clearly due to the noncovalently bound chromophore