Nutritional and phytogeriatological studies of three varieties of Gnetum africanum (‘afang’)

Three varieties of Gnetum africanum viz. the Asutan, Oron and Ikom, commonly consumed in the Southern parts of Nigeria, were assayed for their proximate nutritional composition and fibre characteristics as they related to age of the leaves. Nutritionally, the Asutan variety was significantly (p<0.05) superior to the other two. It had the highest levels of ash, protein, lipid and highest caloric value. It also had the lowest contents of antinutrients such as tannins, oxalates, glucosinolates and hydrocyanic acid, which were all below documented toxic levels. Bioassay using albino rats confirmed the high nutritional value of the Asutan variety. Phytogeriatological assay showed that, in the Asutan variety, protein content, crude fibre, fibre length and fibre width increased with age of the plant, peaking at 6–12 months. There was positive correlation between crude fibre, fibre length and age (p<0.05) whereas crude protein, in vitro digestibility and fibre width were negatively correlated with age. The findings are discussed with special reference to the possible contribution of G. africanum to the nutrient requirements of man in health and disease. A suggestion is also made for the selective cultivation of the Asutan variety over the other two.     

Selection and molecular characterization of wine yeasts isolated from the ‘El Penedès’ area (Spain)

A study of the microbiota present during the wine fermentation of five grape varieties from the ‘El Penedès’ area (Spain) was carried out to select autochthonous yeast strains for industrial wine production. In this study we identified members of the genera Candida, Dekkera, Hanseniaspora, Kluyveromyces, Torulaspora, Zygosaccharomyces and Saccharomyces in wine fermentation microbiota. Strains of Saccharomyces cerevisiae, as responsible agents of the alcoholic fermentation, were considered for a selection protocol. In this work we applied different enological criteria for selection, but previously we have characterized and differentiated Saccharomyces isolates by molecular methods to reduce the number of strains to analyse. Three strains were selected to conduct fermentations according to their characteristics. Finally, using mitochondrial DNA restriction analysis we demonstrated that the autochthonous selected strains are important contributors to the wine fermentation.     

Comparison of the migration of melamine from melamine–formaldehyde plastics (‘melaware’) into various food simulants and foods themselves

A variety of melaware articles were tested for the migration of melamine into the food simulant 3% w/v acetic acid as a benchmark, and into other food simulants, beverages and foods for comparison. The results indicate that the acidity of the food simulant plays a role in promoting migration, but not by as much as might have been anticipated, since 3% acetic acid gave migration values about double those obtained using water under the same time and temperature test conditions. In contrast, migration into the fatty food simulant olive oil was not detectable and at least 20-fold lower than with the aqueous food simulants. This was expected given the solubility properties of melamine and the characteristics of the melaware plastic. Migration levels into hot acidic beverages (apple juice, tomato juice, red-fruit tea and black coffee) were rather similar to the acetic acid simulant when the same time and temperature test conditions are used, e.g. 2?h at 70°C. However, migration levels into foods that were placed hot into melaware articles and then allowed to cool on standing were much lower (6–14 times lower) than if pre-heated food was placed into the articles and then maintained (artificially) at that high temperature in the same way that a controlled time–temperature test using simulants would be conducted. This very strong influence of time and especially temperature was manifest in the effects seen of microwave heating of food or beverage in the melaware articles. Here, despite the short duration of hot contact, migration levels were similar to simulants used for longer periods, e.g. 70°C for 2?h. This is rationalized in terms of the peak temperature achieved on microwave heating, which may exceed 70°C, counterbalancing the shorter time period held hot. There was also evidence that when using melaware utensils in boiling liquids, as for stovetop use of spatulas, the boiling action of circulating food/simulant can have an additional effect in promoting surface erosion, increasing the plastic decomposition and so elevating the melamine release.     

Effect of soy protein supplementation on the nutritive value of ‘gari’ (farina) from Manihot esculenta

The supplementary role of soy protein on cassava (Manihot esculenta) “gari” or farina was studied in 35 day-old albino rats of the Wistar strain (n=6 per group) for 10 days. Gari was supplemented with soy beans at 10 and 15% soy protein levels to produce “soy gari” and the performances of rats fed the test diets compared with those on a 10% casein diet. Protein efficiency ratio (PER), Net protein utilization (NPU), true digestibility (TD) and biological values (BV) were the parameters used to assess the nutritional performance of the diets based on weight gains and nitrogen balance. The PER for 10% casein, 10 and 15% soy protein-supplemented gari groups were 2.31, 1.85 and 1.94 respectively, while the corresponding values for NPU were 71.9, 65.8 and 64.1, respectively. The TD values for the 10% casein, 10 and 15% soy protein-fed rats were 97.2, 91.9 and 90.0, respectively, while the corresponding values for BV were 73.9, 70.9 and 71.5. The PER, NPU, TD and BV for 10% casein diet were significantly superior (P<0.05) to those of the soy gari diets which gave NPU, TD and BV values 89–97% of those of the casein diet. There were no significant differences (P>0.05) in these parameters between the 10 and 15% soy protein supplementation. Soy gari is safe to the consumer, because the procedures involved in processing soy beans and cassava ensure the elimination of toxic anti-nutritional factors known to impact negatively on nutrient availability, metabolic processes and growth. It is suggested that the consumption of soy gari at 10% soy protein supplementation be promoted in gari-eating areas, to ameliorate the endemic problems of protein deficiency disorders.     

Toxicokinetics and carry-over model of α-hexabromocyclododecane (HBCD) from feed to consumption-sized Atlantic salmon (Salmo salar)

A two-compartmental model for the kinetics of carry-over of the brominated flame retardant α-hexabromocyclododecane (HBCD) from feed to the fillet of farmed harvest-sized Atlantic salmon (Salmo salar L.) was developed. The model is based on a fat compartment for storage of the lipophilic α-HBCD and a central compartment comprising all other tissues. Specific for this model is that the salmon has a continuous growth and that fillet contaminant levels are explained by both the fat and the central compartments. The uptake and elimination kinetics are obtained from experimental data where consumer sized (start weight approximately 1 kg) Atlantic salmon was fed α-HBCD spiked feed (280 ± 11 μg kg(-1)) for 2 months followed by a depuration period of 3 months. The model was used to simulate the HBCD feed-to-fillet transfer in Atlantic salmon under realistic farming conditions such as the seasonal fluctuations in feed intake, growth and fillet fat deposition. The model predictions gave fillet concentrations of 0.2-1.8 μg kg(-1) depending on the level of fish oil inclusion in the salmon diets when using fish oil with high POP background levels. Model simulations show that currently farmed Atlantic salmon can contribute to a maximum of 6% of the estimated provisional food reference dose for HBCD.     

Toxicokinetics and carry-over model of α-hexabromocyclododecane (HBCD) from feed to consumption-sized Atlantic salmon (Salmo salar)

A two-compartmental model for the kinetics of carry-over of the brominated flame retardant α-hexabromocyclododecane (HBCD) from feed to the fillet of farmed harvest-sized Atlantic salmon (Salmo salar L.) was developed. The model is based on a fat compartment for storage of the lipophilic α-HBCD and a central compartment comprising all other tissues. Specific for this model is that the salmon has a continuous growth and that fillet contaminant levels are explained by both the fat and the central compartments. The uptake and elimination kinetics are obtained from experimental data where consumer sized (start weight approximately 1?kg) Atlantic salmon was fed α-HBCD spiked feed (280?±?11?µg?kg^?1) for 2 months followed by a depuration period of 3 months. The model was used to simulate the HBCD feed-to-fillet transfer in Atlantic salmon under realistic farming conditions such as the seasonal fluctuations in feed intake, growth and fillet fat deposition. The model predictions gave fillet concentrations of 0.2–1.8?µg?kg^?1 depending on the level of fish oil inclusion in the salmon diets when using fish oil with high POP background levels. Model simulations show that currently farmed Atlantic salmon can contribute to a maximum of 6% of the estimated provisional food reference dose for HBCD.     

Use of β-hydroxyacyl-CoA-dehydrogenase (HADH) activity to differentiate frozen from unfrozen fish and shellfish

 Further work on an enzymic method to differentiate frozen from unfrozen fish and shellfish is reported. The method is based on the release of the β-hydroxyacyl-CoA-dehydrogenase (HADH) from mitochondria during freezing. Enzymic activity was evaluated in fresh and frozen thawed samples from sole (Solea solea), sea bream (Pagellus centrodontus), hake (Merluccius merluccius), gilt headed bream (Sparus aurata), sea bass (Dicentrarchus labrax), salmon (Salmo salar), prawn (Penaeus japonicus) and Norwegian lobster (Nephrops norvegicus). Changes in the HADH activity of fresh and frozen thawed samples were compared after freezing at –196  °C for 15 min. Two values were obtained: U (by dividing: HADH activity of samples frozen at –196  °C, then thawed/HADH activity of unfrozen samples) and F (by dividing: HADH activity of samples frozen at –18  °C, thawed, then frozen at –196  °C /HADH activity of samples frozen at –18  °C, then thawed). Statistical analysis showed significant differences (P≤0.05) between both quotients for gilt headed bream, salmon, sea bream, sole and prawn, and an arbitrary limit was set at 2 to differentiate frozen thawed from unfrozen samples. The application of this limit made it possible to discriminate the unfrozen from the frozen thawed state of around 90% of the total samples analysed. Best results were obtained for prawn (100% of samples differentiated). In the present paper, a laboratory routine is proposed based on the comparison of the HADH activity of a sample analysed straight away and that of a sample frozen at –196  °C and then thawed. The reported method is simple and fast. The entire laboratory procedure can be performed in 45 min. Received: 20 July 1998 / Revised version: 2 November 1998     

Design of Active Modified Atmosphere and Humidity Packaging (MAHP) for ‘Wonderful’ Pomegranate Arils

Modified atmosphere packaging (MAP) systems have been shown as beneficial to prolong postharvest life of pomegranate arils. Current application of such system is limited due to a lack of appropriate packaging films which are able to control in-package moisture condensation. Therefore, the aim of this study was to design a MAP system to balance the optimum gas composition with packaging film permeability as well as optimum in-package relative humidity (RH). The following packaging materials design were used: (i) 100% cellulose-based film NatureFlex (NF), (ii) bi-axial-oriented polypropylene (BOPP)-based film PropaFilm (PF), (iii) NF-PF (66:33%) film, and (iv) PF-NF (33:66%) film. The effects of package design on quality attributes of pomegranate arils stored at 10 °C (91?±?2% RH) for 9 days were investigated. Package design had significant (p?≤?0.05) impact in changing the in-package RH and gas composition. The 100% cellulose-based (NF) package created the lowest RH (60–66%) with highest reduction in O₂ concentration, highest total soluble solids (TSS), hardness, colour change, and high bacterial count. However, the 100% BOPP-based (PF) film resulted in highest in-package water vapour condensation and mould growth at the end of storage. The optimized packages using PF-NF and NF-PF films, respectively, maintained quality of pomegranate arils and minimized water vapour condensation. The results indicated that PF packaging film fitted with NF film window was the best to maintain the quality of pomegranate arils.     

Cyanidin-3-O-(2″-xylosyl)-glucoside, an anthocyanin from Siberian ginseng (Acanthopanax senticosus) fruits, inhibits UVB-induced COX-2 expression and AP-1 transactivation

Cyanidin-3-O-(2″-xylosyl)-glucoside (C-3-O-(2″-xylosyl)-G) was analyzed as an active constituent from the fruit of Siberian ginseng (Acanthopanax senticosus) using a HPLC diode array detection-electrospray ionization/mass spectrometry analysis system and the effect of C-3-O-(2″-xylosyl)-G on UVB-induced inflammatory signaling in JB6 P+ cells was investigated. C-3-O-(2″-xylosyl)-G inhibited UVB-induced cyclooxygenase (COX)-2 expression and promoter binding activity in JB6 P+ cells and JB6 P+ cells stably transfected with the COX-2 luciferase reporter plasmid. It inhibited both the UVB-induced activator protein-1 (AP-1) and nuclear factor (NF)-κB transactivation in JB6 P+ cells stably transfected with the AP-1 and NF-κB luciferase reporter plasmids. Additionally, C-3-O-(2″-xylosyl)-G significantly suppressed UVB-induced upregulated phosphorylation of c-Jun N terminal kinase, MEK/extracellular signaling kinase, and mitogen activated protein kinase kinase (MAPKK) 3/6 in JB6 P+ cells. These results indicate that C-3-O-(2″-xylosyl)-G may be a promising chemopreventive material that acts by suppressing COX-2 expression and AP-1 and NF-κB transactivation and JNK, MAPKK3/6, and MEK/ERK1/2 phosphorylation.     

Binding of ²³⁹Pu and ⁹⁰Sr to organic colloids in soil solutions: evidence from a field experiment

Colloidal transport has been shown to enhance the migration of plutonium in groundwater downstream from contaminated sites, but little is known about the adsorption of ??Sr and plutonium onto colloids in the soil solution of natural soils. We sampled soil solutions using suction cups, and separated colloids using ultrafiltration to determine the distribution of 23?Pu and ??Sr between the truly dissolved fraction and the colloidal fraction of the solutions of three Alpine soils contaminated only by global fallout from the nuclear weapon tests. Plutonium was essentially found in the colloidal fraction (>80%) and probably associated with organic matter. A significant amount of colloidal ??Sr was detected in organic-rich soil solutions. Our results suggest that binding to organic colloids in the soil solutions plays a key role with respect to the mobility of plutonium in natural alpine soils and, to a lesser extent, to the mobility of ??Sr.     

Improving storability,physiological disorders,and antioxidant properties of ‘Bartlett’ and ‘d’Anjou’ pears (Pyrus communis L.) by pre-harvest 1-methylcyclopropene spraying

Ethylene continues to be a major factor influencing quality of European pears during storage. Although research has been done on the effect of pre-harvest 1-methylcyclopropene (1-MCP) on physiological characteristics in pears, a full understanding of cultivar response and antioxidant metabolism remains elusive. Spraying 1-MCP on ‘Bartlett’ and ‘d’Anjou’ pears was studied with respect to physiology, storage and eating quality, disorders, and antioxidant properties at two harvest date (H1 and H2) during storage and ripening. Treatment with 1-MCP extended the harvest window of ‘Bartlett’ and ‘d’Anjou’ pears 3 and 4 days, respectively, without reducing storage or eating quality. Treatment with 1-MCP reduced ethylene production (EPR) and respiration rates (RR), maintained fruit firmness and green colour during storage and retarded development of desirable melting texture in both cultivars. Additionally, 1-MCP lowered the incidence of disorders by alleviating membrane lipid peroxidation, retaining high total flavonoids (TF) and antioxidant capacity, and enhancing superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity in both cultivars. Overall, pre-harvest 1-MCP applications could extend storage time of ‘Bartlett’ and ‘d’Anjou’ pears to 5 and 6 months, respectively, at −1.1 ± 0.5 °C, by reducing ethylene synthesis and enhancing antioxidant metabolism.     

Comparison of the solution properties of (1→3),(1→4)-β-d-glucans extracted from oats and barley

The solution properties of β-glucan isolated from whole grains of oats and barley were studied by viscosity and oscillatory measurements both in water and in aqueous cuoxam, an ammoniacal Cu(OH)₂/CuCl-solution. The viscosity measurements of water solutions show stronger shear thinning for oat than for barley β-glucans. The crossover points of the moduli G′ and G″ in cuoxam solutions were different for the two β-glucans, i.e. 10 Hz for oat β-glucan and 1.5 Hz for barley β-glucan. The molecular weights of the β-glucans were similar. Therefore, the difference in solution properties seems to be related to the difference in structure. This difference is revealed by the ratio DP3:DP4 of the main building blocks of β-glucans, which was higher for barley than for oat β-glucan.     

Changes in cuticle compositions and crystal structure of ‘Bingtang’ sweet orange fruits (Citrus sinensis) during storage

Changes in composition and structure of orange cuticle during storage at 4°C or 25°C for 40 days were investigated. The total epicuticular wax content of fruits increased during storage at 4°C for 30 days and then decreased as storage time prolonged to 40 days, while it increased continuously at 25°C for 40 days. The total intracuticular wax content of fruits increased to 9.70 μg cm^?2 stored at 4°C for 10 days and then decreased to 6.74 μg cm^?2 for 40 days. The total intracuticular wax content of fruits was decreased to 5.17 μg cm^?2 stored at 25°C for 10 days and then increased to 10.06 μg cm^?2 for 30 days. Fatty acids were the most abundant component of the epicuticular wax and terpenoids were restricted to the intracuticular wax. Terpenoids were restricted to the intracuticular wax, and their amounts in the fruit stored at 4°C increased continuously during the first 20 days of storage at 4°C and then decreased as storage time increased up to 40 days. Although significant changes were found in the contents of the cutin monomer, their proportions did not change significantly during storage at 4°C or 25°C. Size of wax platelets crystals wax increased during storage of fruits at 4°C up to 30 days; however, the crystals were degraded and decreased as storage prolonged to 40 days. Furthermore, the shape of the fruit cuticle surface wax crystals changed from flattened platelets to small granulelike after storage at 25°C for 20–40 days. The obtained results provide detailed information about the changes in orange cuticle occur during storage at varying temperatures, which may help in preserving the quality of citrus fruits during storage.     

Rapid purification and characterization of γ-glutamyl-transpeptidase from shiitake mushroom (Lentinus edodes)

γ-Glutamyl-transpeptidase (GGT) is one of the important enzymes in the pathway of odor formation in shiitake mushroom (Lentinus edodes). Rapid purification and characterization of GGT from shiitake mushroom were studied in this work. The GGT was purified 179-fold after 3 primary steps: precipitation by ammonium sulfate, isolation by Phenyl Sepharose 6 FF, and desalting by Sephadex G-25. The enzyme, consisting of a small and a large subunit with Mr 28 KDa and 60 KDa, respectively, is composed of 17 kinds of amino acids with the ratio of basic and acidic residues 1 : 1.84, and its secondary structure was also determined by Fourier transform infrared spectroscopy. The properties of GGT were studied with γ-glutamyl-p-nitroanilide as the substrate. The results showed Km value of 2.601 μM, optimal temperature of 40 °C, and isoelectric point of 6.4. In addition, the activity of GGT was promoted by Na(+), K(+), and Ca(2+) and inhibited by Cu(2+), Ag(+), Zn(2+), and Fe(3+). PRACTICAL APPLICATION: In this work, the γ-glutamyl-transpeptidase (GGT) from shiitake mushroom was purified with a simple scheme. Through the characterization of GGT, the relationship between endogenous formaldehyde and odor formation is to be clarified and assist in finding means of formaldehyde control in shiitake mushroom.