The comparison of biosorption of nutritionally significant minerals in single‐ and multi‐mineral systems by the edible microalga Spirulina sp.

BACKGROUND: This paper deals with the biosorption process as a method of enrichment of natural biomass of the edible microalga Spirulina sp. with microelement metal ions, which is of significance in terms of animal nutrition. The influence of the following process parameters was studied for the biosorption of Cr(III): pH and biomass concentration on kinetics and equilibrium of biosorption. The enrichment process were performed in single‐ and multi‐mineral systems for nutritionally significant minerals such as Cu(II), Mn(II), Co(II), Zn(II) and Cr(III) under the conditions that were determined for Cr(III). RESULTS: The best operational parameters for the process were selected as pH 5 and Cs 1 g L^?1. The maximum biosorption capacity 71.2 mg g^?1, 18.4 mg g^?1, 83.9 mg g^?1, 31. 8 mg g^?1 and 26.5 mg g^?1, were reached for Cu(II), Mn(II), Co(II), Zn(II) and Cr(III), respectively. To cover 100% of animal demand on microelements, 4.91 g of the preparation for laying hens and 9 g for swine of enriched microalgae in the single‐metal system should be added to 1 kg of fodder. In the multi‐metal system the competition between microelements was high enough to make it impossible to reach a suitable ratio between bound metal ions. CONCLUSIONS: Two methods of production of mineral feed additives were proposed: a single‐metal system and a multi‐metal system. Performing the biosorption process in the single‐metal system enabled the preparation of additives with the desired composition. Carrying out biosorption in the multi‐metal system is easier, technologically, but the ratio of bound microelements is difficult to predict. Copyright © 2009 Society of Chemical Industry     

Effect of processing and storage of brined white (Nabulsi) cheese on fat and cholesterol oxidation

Brined white (Nabulsi) cheese was studied for cholesterol oxidation and for oxidative and hydrolytic rancidities during cheese processing, during storage in closed transparent and light‐protected glass jars at room temperature for 3, 6 and 9 months and during storage on an open tray exposed to atmospheric air and light for 1, 2 and 3 weeks. The peroxide value (PV), free fatty acid (FFA) content and 7‐ketocholesterol level were determined. The cheese processing steps (curd formation, salting and boiling in brine) had no significant effect on PV, FFAs and 7‐ketocholesterol. However, the storage conditions had a significant effect (p ≤ 0.5) on these parameters. Peroxides were not detected or were very low in the freshly boiled cheese, while the FFA content was 2.9 g kg^?1. The PV and FFA content increased to approximately 5 meq kg^?1 and 11 g kg^?1 respectively after 9 months of storage in transparent or light‐protected jars. The 7‐ketocholesterol level was 1.2 µg g^?1 in the freshly boiled cheese and reached maximum values of 2.3 and 5.2 µg g^?1 after 9 months of storage in light‐protected and transparent jars respectively. Cheese samples displayed on an open tray showed a higher increase in PV, FFAs and 7‐ketocholesterol than samples stored in closed jars, reaching values of 6.1 meq kg^?1, 6.8 g kg^?1 and 8.8 µg g^?1 respectively after 3 weeks of storage. © 2002 Society of Chemical Industry     

Intensity of lipid oxidation and formation of cholesterol oxidation products during frozen storage of raw and cooked chicken

Raw and cooked chicken breasts were stored at ?18 °C for 3 months under aerobic and vacuum conditions, and the intensity of lipid oxidation and the formation of COP (cholesterol oxidation products) were studied. Raw samples showed low COP levels (4.60–7.40 µg g^?1 fat), TBARS (thiobarbituric acid reactive substances) levels (0.01–0.03 mg kg^?1) and peroxide values (not detected) under both aerobic and vacuum conditions. Cooked samples (grilled and roasted) showed TBARS levels of 0.36–0.99 mg kg^?1 in aerobic conditions and 0.21–0.70 mg kg^?1 in vacuum conditions, whilst peroxide levels reached 38–40 and 19–23 meq O₂ kg^?1 in samples stored under aerobic and vacuum conditions respectively. Total COP levels in grilled and roasted samples were 28.91 and 39.34 µg g^?1 fat in aerobic packaging and 4.90 and 20.24 µ g g^?1 fat in vacuum packaging respectively. Significant correlations were found between the lipid oxidation parameters and cholesterol oxidation indices. In general, TBARS were better correlated with total COP than with only 7‐ketocholesterol. Vacuum packaging was particularly efficient in slowing down the oxidation process during frozen storage of cooked samples. Copyright © 2004 Society of Chemical Industry     

Antioxidant activities of different Teucrium montanum L. Extracts

The sequential extraction of Teucrium montanum L. was realised with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, and n‐butanol) and HPLC method was used for identification of phenolic compounds. The total phenolic content of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and range from 0 to 296 mg g^?1. The antioxidant activity of extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using electron spin resonance (ESR) spectroscopy. Moreover, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (1) sunflower oil (37 °C, 3 h) induced by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and (2) liposomes induced by 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH) was studied. n‐Butanol extract, because of the highest content of total phenolic compounds (296 mg g^?1) had the best antioxidant activity (100% at 0.16 mg mL^?1 in Fenton reaction system; 90.57% at 5 mg mL^?1 in system I; 100% at 5 mg mL^?1 in system II).     

Antioxidant activity of phytogenous industrial waste and derived extracts for the production of feed and food additives

Organic wastes as well as their ethanolic, water and heptane extracts and fermented products derived from herbs, fruit and vegetables obtained worldwide from food and pharmaceutical industries were investigated regarding their antioxidant activities using different methods [1.1‐diphenyl‐2‐picrylhydrazyl, Fe^III‐reduction method and photochemiluminescence (PCL)]. The highest antioxidative activities were exhibited by different products of grape seed wastes (350–830 mg rosmarinic acid equivalent g^?1 dried material = rae g^?1 dm) followed by ethanolic extracts of blueberry (475 mg rae g^?1 dm), larch (219 mg rae g^?1 dm), willow (193 mg rae g^?1 dm) and sunflower presscake (154 mg rae g^?1 dm). Ethanolic extracts of the residues showed comparatively higher activity than water extracts. The least antioxidative capacities were found in heptane extracts of serenoa products (0.4; 0.6 mg rae g^?1 dm) and fermented waste of carrots (1.6 mg rae g^?1 dm). Correlating different assay methods, the strongest correlation was found between Fe^III‐reduction and DPPH‐method (correlation coefficient r² = 0.99**) and the weakest between Fe^III‐reduction and PCL method (r² = 0.57**) for raw materials.     

Broad bean and pea by‐products as sources of fibre‐rich ingredients: potential antioxidant activity measured in vitro

BACKGROUND By‐products generated during the processing of plant food can be considered a promising source of dietary fibre as a functional compound. The dietary fibre composition, soluble sugars and antioxidant activity of the extractable polyphenols of pea and broad bean by‐products have been analysed in this study. RESULTS: Total dietary fibre using AOAC methods plus hydrolysis (broad bean pod: 337.3 g kg^?1; pea pod: 472.6 g kg^?1) is higher (P < 0.05) in both by‐products than with the Englyst method (broad bean pod: 309.7 g kg^?1; pea pod: 434.6 g kg^?1). The main monomers are uronic acids, glucose, arabinose and galactose in broad bean pods. However, pea pods are very rich in glucose and xylose. The soluble sugars analysed by high‐performance liquid chromatography in both by‐products have glucose as the most important component, followed by sucrose and fructose. The ferric reducing antioxidant power (broad bean pod: 406.4 µmol Trolox equivalents g^?1; pea pod: 25.9 µmol Trolox equivalents g^?1) and scavenging effect on 2,2‐diphenyl‐1‐picrylhydrazyl radical (EC₅₀ of broad bean pod: 0.4 mg mL^?1; EC₅₀ of pea pod: 16.0 mg mL^?1) were also measured. CONCLUSIONS: Broad bean and pea by‐products are very rich in dietary fibre, particularly insoluble dietary fibre and their extractable polyphenols demonstrate antioxidant activity. Therefore they might be regarded as functional ingredients. Copyright © 2011 Society of Chemical Industry     

Mineral contents of some aromatic plants,their growth soils and infusions

BACKGROUND: In this study, 18 kinds of medicinal plants were collected together with their soils from different regions of Turkey and their macro‐ and micro‐element and heavy metal contents were determined by inductively coupled plasma atomic emission spectrometry (ICP‐AES). In soils, pH, electrical conductivity, carbonate (lime), organic matter, texture, P, K, Ca, Mg, Fe, Cu, Mn, Zn and B were analysed. In plants and extracts, P, K, Ca, Mg, Fe, Cu, Mn, Zn, B, Na, Al, Li, Pb, Ni, Cd, Co and Cr contents were determined. Also, correlations between soil and plant and between plant and extract were established. RESULTS: Element concentrations ranged between 0.11 and 5160 µg g^?1 in soil samples, between 0.14 and 54400 µg g^?1 in plant samples and between 0.039 and 22033 µg g^?1 in extract samples. While sage was rich in Fe (981.3 µg g^?1), basil was abundant in P (9.8 mg g^?1), K (54.4 mg g^?1), Ca (22.6 mg g^?1), Mg (3.1 mg g^?1) and Zn (46.05 µg g^?1) and mint was rich in Li (23.50 µg g^?1). Moreover, while high levels of P (4100.9 µg g^?1), K (22033 µg g^?1) and Mg (529.15 µg g^?1) were found in basil extract, Ca (5979.3 µg g^?1) was present at high concentration in marjoram leaf extract. Also, Fe (4.25 µg g^?1) and Zn (17.51 µg g^?1) were detected at high levels in lime flower and mint extracts respectively. CONCLUSION: It was concluded that aromatic plants are important sources of nutrients and essential elements. Copyright © 2007 Society of Chemical Industry     

Change in α‐tocopherol contents,lipid oxidation and fatty acid profile in eggs enriched with linolenic acid or very long‐chain ω3 polyunsaturated fatty acids after different processing methods

The influences of dietary supplementation with α‐tocopheryl acetate (α‐TA) and of processing (by hard‐boiling and scrambling) of eggs enriched with ω3 fatty acids, either very long‐chain ω3 polyunsaturated fatty acids (VLC ω3 PUFAs) or linolenic acid (LNA), on fatty acid composition, α‐tocopherol content and lipid oxidation (thiobarbituric acid (TBA) values) were studied. Four dietary treatments were formulated from a basal diet containing 40 g kg^?1 linseed oil (LO) or fish oil (FO) combined with either 0 or 100 mg α‐TA kg^?1 of feed. Eggs from LO treatments were enriched with LNA and those from FO treatments were rich in VLC ω3 PUFAs. Neither processing nor dietary supplementation with α‐TA modified greatly the fatty acid profile of eggs. Dietary supplementation with α‐TA increased the α‐tocopherol content of eggs (187.2 versus 407.9 µg g^?1 dry matter). Eggs from FO treatments showed lower α‐tocopherol content than those from LO treatments (273.5 versus 321.6 µg g^?1 dry matter), and processing of eggs enriched with VLC ω3 PUFA reduced the α‐tocopherol content by a significant 16%. Moreover, processing of eggs increased lipid oxidation two‐ to nine‐fold. Oxidation levels of hard‐boiled eggs were 30.4% higher than those of scrambled eggs. TBA values in hard‐boiled and scrambled eggs were significantly reduced when 100 mg α‐TA kg^?1 of feed supplemented the diet only in those eggs enriched with VLC ω3 PUFA (from FO treatments). Copyright © 2003 Society of Chemical Industry     

Chemical analysis and acetylcholinesterase inhibitory effect of anthocyanin-rich red leaf tea (cv. Sunrouge)

BACKGROUND: The purpose of this study was to evaluate the effects of leaf order or crop season on anthocyanins and other chemicals in the anthocyanin‐rich tea cultivar ‘Sunrouge’ (Camellia sinensis x C. taliensis) by using high‐performance liquid chromatography, and to study the effect of ‘Sunrouge’ extract on acetylcholinesterase (AChE) activity in human neuroblastoma SK‐N‐SH cells. RESULTS: The total anthocyanin content was higher in the third (3.09 mg g^?1) than in the second (2.24 mg g^?1) or first crop season (1.79 mg g^?1). The amount of anthocyanins contained in the stem was high (1.61 mg g^?1). In the third crop season, the concentrations of delphinidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside (DCGa), cyanidin‐3‐O‐β‐D ‐(6‐(E)‐p‐coumaroyl)galactopyranoside, delphinidin‐3‐O‐β‐D ‐galactopyranoside, delphinidin‐3‐O‐β‐D ‐(6‐O‐(Z)‐p‐coumaroyl)galactopyranoside, cyanidin‐3‐O‐β‐D ‐galactoside, and delphinidin‐3‐O‐β‐D ‐glucoside were 1.57 mg g^?1, 0.52 mg g^?1, 0.40 mg g^?1, 0.22 mg g^?1, 0.14 mg g^?1, and 0.11 mg g^?1, respectively. DCGa accounted for about 50% of the anthocyanins present. The suppressive effect of ‘Sunrouge’ water extract on AChE activity in human neuroblastoma SK‐N‐SH cells was the strongest among the three tea cultivars (‘Sunrouge’, ‘Yabukita’ and ‘Benifuuki’). CONCLUSION: These results suggested that ‘Sunrouge’ might protect humans from humans from AChE‐related diseases by suppressing AChE activity. To obtain sufficient amounts of anthocyanins, catechins and/or caffeine for a functional food material, ‘Sunrouge’ from the third crop season should be used. Copyright © 2012 Society of Chemical Industry     

A study on chemical estimation of pu‐erh tea quality

Chemical compositions and infusion colour differences of seven pu‐erh tea samples and their correlation to sensory quality were investigated. The results showed that the pu‐erh tea contained 37.1 mg g^?1 caffeine, 15.7 mg g^?1 amino acids, 67.0 mg g^?1 polyphenols and 8.41 mg g^?1 total catechins, on average. Among the 17 tested volatile compounds, n‐valeraldehyde was not detected. The most abundant volatile was β‐ionone and the next was linalool oxide II. Infusion colour analysis showed that the pu‐erh tea had deep hue with ΔE ranging from 66.8 to 79.2. Spearman's linear correlation analysis showed that total quality score (TQS) of the pu‐erh tea was significantly correlated to concentration of amino acids, linalool oxide II and infusion colour indicator ΔE. Five components were extracted from the 34 tested indicators by principal component analysis and were regressed on the TQS to produce six Pearson's linear regression equations for estimating sensory quality of pu‐erh tea, among which two were statistically significant, ie TQS = 57.47 ? 0.18geraniol + 0.33polyphenols ? 1.14n‐caproaldehyde ? 1.38linalool oxide I + 0.21caffeine (p < 0.01) and TQS = 57.42‐0.03Citral + 0.33polyphenols ? 1.14n ? caproaldehyde ? 1.40linalool oxide I + 0.20caffeine (p < 0.01). Copyright © 2004 Society of Chemical Industry     

Variations in antioxidant properties of strawberries grown in Brazilian savannah and harvested in different seasons

BACKGROUND: Strawberries are nutritive fruits and a source of antioxidants. We evaluated antioxidant properties of ‘Camino Real’ strawberries grown in the Brazilian savannah, harvested in different seasons. Analytical and meteorological data were analyzed by partial least squares regression. RESULTS: Fruits from May showed the lowest contents of total phenolics (1789.78 mg kg^?1 fresh weight (FW)), catechin (21.37 mg kg^?1 FW), quercetins (4.89 mg kg^?1 FW) and total ellagic acid (208.68 mg kg^?1 FW) and the lowest antioxidant activity by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) (11.39 mg Butylated hydroxytoluene (BHT) eq. g^?1 FW) and ferric reducing antioxidant power (FRAP) (22.01 mg ferrous sulfate eq. g^?1 FW) assays. Strawberries harvested in July presented the lowest concentrations of total (190.61 mg kg^?1 FW) and individual anthocyanins (73.88 mg kg^?1 FW and 5.96 mg kg^?1 FW for pelargonidin‐3‐glucoside and cyanidin‐3‐glucoside, respectively), but the highest contents of vitamin C (685.47 mg kg^?1 FW), DPPH (18.87 mg BHT eq. g^?1 FW) and FRAP (39.30 mg ferrous sulfate eq. g^?1 FW). The highest contents of free ellagic acid (26.11 mg kg^?1 FW), pelargonidin‐3‐glucoside (291.82 mg kg^?1 FW) and cyanidin‐3‐glucoside (11.84 mg kg^?1 FW) were found in strawberries from September. Rain in the previous 30 days to harvest influenced negatively many phenolics and antioxidant activity of strawberries harvested in May. In July, longer photoperiod and lower temperature at 30 days previous to harvest probably led to higher antioxidant activity and vitamin C. Increased photoperiod and temperature at the final stage of maturation seem to raise pigments and free ellagic acid in strawberries. CONCLUSION: It was possible to observe significant relationships among meteorological and antioxidant variables for strawberries grown in the Brazilian savannah. Copyright © 2011 Society of Chemical Industry     

Optimum aqueous extraction conditions for preparation of a phenolic‐enriched Davidson's plum (Davidsonia pruriens F. Muell) extract

This study aimed to optimise aqueous extraction conditions for total phenolic compounds (TPC) from Davidson's plum (Davidsonia pruriens F. Muell) and to assess the physicochemical and antioxidant properties of the phenolic‐enriched extract. The results showed that temperature, time and ratio significantly affected the extraction of TPC. Optimization of extraction conditions was performed using response surface methodology (RSM) utilising a Box–Behnken design. Optimal extraction conditions were determined to be temperature: 90 °C, extraction time: 30 min and solvent to mass ratio: 20:1 mL g^?1. The extracted solid obtained under these conditions had low‐moisture content, high water solubility and contained 45 mg GAE g^?1 of TPC, 22 mg RUE g^?1 of flavonoids, 3.2 mg CAE g^?1 of proanthocyanidins, 2 mg CGE g^?1 of anthocyanidins and 56 mg ACE g^?1 vitamin C. The extract possessed potent antioxidant capacity, but was comparatively lower than those of vitamin E and BHT. Thus, Davidson's plum should be further investigated for its potential health promoting benefits and utilisation in the nutraceutical and food industries.     

Characteristics of fibre‐rich powder and antioxidant activity of pitaya (Hylocereus undatus) peels

The contents of total dietary fibre (TDF), soluble dietary fibre (SDF), insoluble dietary fibre (IDF) and functional properties of fibre‐rich powders (FRP) from pitaya peels with different particle size (FRP80, FRP140 and FRP250) were determined. Results showed that FRP140 had higher TDF (79.37%) and SDF (33.07%) with a balanced ratio of SDF/IDF (1:1.32) and higher water‐holding capacity (54.20 g g^?1), swelling capacity (50.63 mL g^?1), oil‐holding capacity (2.65 g g^?1) and glucose dialysis retardation index (62.83% at 60 min), compared with FRP80 and FRP250. Therefore, physiochemical properties of FRP140 were further investigated. SDF of FRP140 mainly contained rhamnose (4.95%) and galactose (1.98%), with 9.45% galacturonic acid, while IDF dominantly contained xylose (4.76%) and galactose (3.42%), with 18.54% klason lignin. Total phenolic content was 7.75 mg g^?1 and mainly composed of salicylic acid (0.98 mg g^?1) and protocatechuic acid (0.45 mg g^?1). Furthermore, FRP140 showed significant reducing power, DPPH‐scavenging activity and nitrite‐scavenging ability.     

Glutaminase‐induced deamidation and hydrolysis of casein and metal‐chelating or ACE‐inhibitory activity of the hydrolysates in vitro

Glutaminase (EC 3.5.1.2) was applied in this work to induce deamidation and hydrolysis of casein. Some reaction conditions based on casein deamidation were studied. Three casein hydrolysates with degree of deamidation of 2.8%, 5.8% and 8.5%, or degree of hydrolysis of 2.5%, 3.4% and 4.9%, respectively, were prepared at casein concentration 5% (w/v), glutaminase addition level 400 U kg^?1 casein, reaction temperature 37 °C and reaction times 6, 12 and 24 h, respectively. Evaluation results showed that when iron (II) was added at 60 μm , iron (II)‐chelating powers of three hydrolysates were 41.1, 45.4 and 55.3%, while that of original casein and EDTA were 36.1 and 13.6%. Calcium (II)‐chelating power of three hydrolysates was 1.23, 1.41 and 1.49 mmol g^?1 casein, whereas that of original casein was 1.05 mmol g^?1 casein. Three hydrolysates also had ACE‐inhibitory activity in vitro, with IC₅₀ values from 0.75 to 2.34 mg mL^?1.     

Antioxidant activity and phenolic content of lentils (Lens culinaris), chickpeas (Cicer arietinum L.), peas (Pisum sativum L.) and soybeans (Glycine max), and their quantitative changes during processing

Total phenolic content (PC) was ～12 mg g^?1 in lentils, 2.2 mg g^?1 in chickpeas, 2.3 mg g^?1 in soybeans, 2.5 mg g^?1 in yellow peas and 1.2 mg g^?1 in green peas. Total antioxidant activity (AA) determined by ABTS (2,2′‐azinobis‐3‐ethyl‐benzthiazoline‐6‐sulfonic acid) assay was highest in lentils at around 14 μmol Trolox equivalent antioxidant capacity (TEAC) g^?1 and lowest in green peas at 1.9 μmol TEAC g^?1. Bound phytochemicals contributed to 82–85% total AA in lentils. Free phytochemicals contributed more to total AA in chickpeas, yellow peas, green peas and soybeans than bound phytochemicals. AA and PC was reduced by ～80% in lentils and <30% in yellow peas by decortication, by 16–41% in lentils, chickpeas and peas by cooking, and by 22–42% in lentils by soaking. Total AA was significantly correlated with total PC. Soybeans had the greatest ability to scavenge free radicals, inhibit lipid peroxidation and chelate metals among the legumes tested. Different legumes exhibited different AA mechanisms.     

Composition and bioavailability of oxalates in baked taro (Colocasia esculenta var. Schott) leaves eaten with cows milk and cows milk and coconut milk

Taro leaves are an important food in the Pacific Islands but the overall oxalate composition and its nutritional effect has not been investigated. The oxalate contents of taro leaves were determined using chemical and in vitro extraction methods. Maori‐type taro leaves contained 524.2 ± 21.3 mg total oxalates 100 g^?1 fresh weight (FW) and 241.1 ± 20.9 mg soluble oxalates 100 g^?1 FW while the Japanese‐type leaves contained 525.6 ± 19.9 mg total oxalates 100 g^?1 FW and 330.4 ± 28.3 mg soluble oxalates 100 g^?1 FW. Maori‐type taro leaves contained 416.4 ± 1.5 mg gastric soluble oxalates 100 g^?1 FW and 212.4 ± 34.8 mg intestinal soluble oxalates 100 g^?1 FW while the Japanese‐type leaves contained 433.3 ± 9.7 mg gastric soluble oxalates 100 g^?1 FW and 224.2 ± 38.7 mg intestinal soluble oxalates 100 g^?1 FW). Human feeding experiments were conducted to determine the availability of the oxalates in the baked leaves following additions of cows milk and coconut milk. The consumption of a test meal of baked taro leaves resulted in a significant increase (P < 0.001) in the output of urinary oxalate in the following 6 h when compared to the output of oxalate during a reference collection. When the leaves were baked with cows milk or cows milk and coconut milk combined and consumed there was a small non‐significant reduction in urinary oxalate output which suggests that less soluble oxalate was absorbed from these mixtures.     

Determination of heavy metal ions in vegetable samples using a magnetic metal–organic framework nanocomposite sorbent

This paper describes the synthesis and application of a novel magnetic metal–organic framework (MOF) [(Fe₃O₄-benzoyl isothiocyanate)/Cu₃(benzene-1,3,5-tricarboxylate)₂] to pre-concentrate trace amounts of Cd(II), Pb(II), Zn(II) and Cr(III) ions and their determination by flame atomic absorption spectrometry. A Box–Behnken design was used to find the parameters affecting the pre-concentration procedure through response surface methodology. Three factors including uptake time, amount of the magnetic sorbent and pH of the sample were selected as affecting factors in the sorption step, and four factors including type, volume and concentration of the eluent as well as the elution time were selected in the elution step for the optimisation study. The opted values were 30 mg, 10.1 min, 5.9, EDTA, 4.0 ml, 0.57 mol l^–1 EDTA solution and 13.0 min for the amount of the magnetic sorbent, uptake time, pH of the sample, type, volume, concentration of the eluent, and elution time, respectively. The limits of detection (LODs) were 0.12, 0.7, 0.16, and 0.4 ng ml^?1 for Cd(II), Pb(II), Zn(II) and Cr(III) ions, respectively. The relative standard deviations (RSDs) of the method were less than 7.2% for five separate batch experiments for the determination of 30 μg l^?1 of Cd(II), Pb(II), Zn(II) and Cr(III) ions. The sorption capacity of the [(Fe₃O₄-benzoyl isothiocyanate)/MOF] was 175 mg g^?1 for Cd(II), 168 mg g^?1 for Pb(II), 210 mg g^?1 for Zn(II) and 196 mg g^?1 for Cr(III). It was found that the magnetic MOF nanocomposite demonstrated a higher capacity compared with Fe₃O₄-benzoyl isothiocyanate. Finally, the magnetic MOF nanocomposite was successfully applied to the rapid extraction of trace amounts of the heavy metal ions from vegetable samples.     

Effects of drying process on biochemical and microbiological quality of silverside (fish) Atherina lagunae

Changes in biochemical and microbiological quality of silverside during two drying process were investigated. Total fatty acid and amino acid contents in silverside were 5.42 and 10.9 g 100 g^?1 fresh sample, respectively, in which, palmitic acid and glutamic acid were the most abundant. N‐3 and n‐6 polyunsaturated fatty acids (PUFA) levels were 0.59 and 0.62 g 100 g^?1 fresh silverside respectively. After hot air and solar drying treatments, Peroxide value and thiobarbituric acid reactive substances of the total lipids increased significantly (P < 0.05) to reach 2.58 and 3.41 meq active O₂ kg^?1 oil and 0.87 and 1.27 mg MA kg^?1 oil, respectively. Fatty acid profile of non‐polar lipid remains unchanged during experimental drying process. However, PUFA (% of total fatty acids) of polar lipid decreased significantly (P < 0.05) during both drying process with lower levels in solar drying process. Drying conditions had a significant effect on the microbiological quality. Therefore, mesophiles and total coliforms increased within drying treatment with higher counts in solar drying process.     

Application of ultrafiltration in the study of phenolic isolates and melanoidins from pale and black brewers' spent grain

Two types of brewers' spent grain (BSG), pale and black, were studied employing ultrafiltration (UF cut‐off, 10 kDa) to obtain high‐molecular‐weight (HMW) and low‐molecular‐weight (LMW) phenolic fractions from one pale (P2) and one black (B2) BSG extracts. Of the four UF fractions obtained, the HMW B2 fraction had highest level of polyphenols (5.73 ± 0.25 mg GAE g^?1 BSG dw) and protein (18.82 ± 0.41 mg protein g^?1 BSG dw). Metal‐chelating ability and antioxidative properties were also identified. Antioxidant activity evaluated using the DPPH and FRAP assays, indicated that activity in B2 extracts was associated mainly with the HMW fraction (3.10 ± 0.10 and 2.49 ± 0.09 TE g^?1 BSG dw, respectively), whereas in P2 samples, antioxidant activity was highest in LMW fractions (0.58 ± 0.01 and 0.92 ± 0.03 TE g^?1 BSG dw, respectively). The high antioxidant activity and metal‐chelating ability observed for black BSG extracts may be attributed to the presence of coloured melanoidinic structures.     

Determination of selenium concentration in rice and the effect of foliar application of Se‐enriched fertiliser or sodium selenite on the selenium content of rice

Atomic fluorescence spectrophotometry was used to determine the selenium (Se) concentration in 30 rice products of different species from Southern China. The Se level ranged from 0.015 to 0.046 µg g^?1. Considering the average daily individual consumption of rice products in Southern China, the average dietary intake of Se supplied by this source is only 6–18 µg day^?1 for an adult. This low Se intake from rice products is mainly responsible for the low total Se intake of inhabitants in Southern China. Foliar spraying of Se‐enriched fertiliser or sodium selenite with 14–18 g Se ha^?1 in the heading stage of rice growth increased the Se content to 0.178–0.421 µg g^?1 in rice products. The concentration and amount of Se‐enriched fertiliser can be varied to achieve an optimum concentration of Se in rice products. The authors suggest that these Se‐enriched rice products can contribute an increase in Se intake of 50–100 µg day^?1 on average if their Se concentration is controlled in the region of 0.15–0.50 µg g^?1. © 2002 Society of Chemical Industry