The interaction of metal ions with Maillard reaction products in a lactose–glycine model system

The influence of Cu²⁺, Fe²⁺ and Zn²⁺-ions on Maillard model reactions was studied by heat treatment of lactose/glycine model solutions. The presence of metals affected the intensity of browning. Fe²⁺-ions stimulated the accumulation of colored compounds at all concentrations (20–100 mg/L) tested, Cu²⁺ and Zn²⁺ only at the lowest concentrations applied (1 and 5 mg/L, respectively) but to a higher extent. Cu²⁺ and Zn²⁺-ions at the highest concentrations applied (5 and 25 mg/L, respectively) suppressed browning of the model mixtures. The relative amounts of metal ions incorporated into the high molecular weight melanoidin fraction increased initially with the reaction time, but near the end of the reaction time studied (5 h, reflux conditions) Cu²⁺ and Fe²⁺-ions were released again from the melanoidins. The amounts of metal ions incorporated into the lactose–glycine melanoidins and their influence on Maillard browning of the different fractions depended on the time of interaction and the nature and concentration of the incorporated metals.     

Characterization of amylase and protease produced by Aspergillus awamori in a single bioreactor

The aim of this study was to characterize the glucoamylase and acid protease produced in a single bioreactor by Aspergillus awamori: nakazawa MTCC 6652. Both the enzymes were found stable in wide range of pH (3–9) and temperature (25–70 °C). Optimum activities of amylase and protease were obtained at pH 4 and 5, respectively, whereas 70 and 55 °C had been found as most suitable temperature for highest activities of amylase and protease, respectively. Half life of glucoamylase was 210, 120, 60 and 35 min at 50, 60, 70 and 80 °C, respectively, which was 150, 120, 65 and 15 min at 40, 50, 60 and 70 °C, respectively, for acid protease. K_m and V_max of glucoamylase and protease were 9.8 mg/ml, 56.2 mg/ml/min and 1.08 mg/ml, 8.8 mg/ml/min, respectively. In low amount (1 mM) almost all metal ions except Mn, such as Ca²⁺, Co²⁺, Cu²⁺, Fe³⁺, Mg²⁺, Zn²⁺ and Hg²⁺ enhanced glucoamylase activity whereas protease activity was inhibited by all the ions except Zn²⁺. At low concentration, i.e., (0.03% w/v) Triton X-100 and SLS increased the activity of glucoamylase, while in higher concentration it inhibited activities of both the enzymes. β-mercaptoethanol at 0.25% (v/v) enhanced the amylase and protease activity by 1.6 and 3.0 fold, respectively, whereas the presence of 0.5% (v/v) β-mercaptoethanol inhibited the activities of both the enzymes drastically. At 0.5 M concentration of urea, glucoamylase activity increased but drastic inhibition took place at 5 M urea. In case of protease, 0.5 M of urea enhanced its activity and 1 M urea inhibited it completely. Thus, glucoamylase and protease produced by A. awamori nakazawa confirm their suitability for diverse applications in industries.     

Determination of major metal cations in milk by capillary zone electrophoresis

A reliable and rapid capillary zone electrophoresis method for the determination of the major of cations in milk samples was developed. Sample preparation consisted of dilution, acidification to pH 4.0 with 1 mol L⁻¹ acetic acid and filtration. The complete separation of K⁺, Ca²⁺, Na⁺ and Mg²⁺ could be achieved in 4 min with a simple electrolyte composed of 10 mmol L⁻¹ imidazole and 1 mol L⁻¹ acetic acid (pH 3.6). The running voltage was 25 kV at 25 °C. Indirect UV detection was achieved at 185 nm. Detection limits ranged from 0.06 to 0.57 mg L⁻¹ and quantification limits ranged from 0.16 to 0.62 mg L⁻¹. Precision data showed relative standard deviations (RSD%) lower than 4.1% for relative migration time and 2.4% for milk concentrations, respectively. Recoveries of cations in samples analysed ranged from 97.7% to 101.1%. Thirty samples of milk were analysed, obtaining mean values of 1.46, 1.19, 0.505 and 0.126 g L⁻¹ for K⁺, Ca²⁺, Na⁺ and Mg²⁺, respectively.     

Application of bacteriophages during depuration reduces the load of Salmonella Typhimurium in cockles

As bivalve molluscs are filter feeder, often consumed raw or lightly cooked and are frequently cultivated in contaminated waters, they are implicated in food-borne disease transmission to human. The present study investigated the potential application of bacteriophage (or phage) phSE-2, phage phSE-5 and phage cocktail phSE-2/phSE-5 to decrease the concentration of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) during the depuration of natural and artificially contaminated cockles (Cerastoderma edule). Cockles were artificially infected with 10⁵ and 10⁶ colony-forming units (CFU)/mL of S. Typhimurium in static seawater and infected group were treated with phages at four different MOI values: 0.1, 1, 10 and 100. Depuration in static seawater at multiplicity of infection (MOI) of 0.1 with single phage suspensions of phSE-2 and phSE-5 provided the best results, as it decreased by ~ 1.3 and 1.7 log CFU/g, respectively, the concentration of Salmonella spp. after a 4 h treatment. At a MOI of 0.1, the rate of inactivation with single phage suspensions was higher when compared with the results obtained using the phage cocktail. However, in naturally contaminated cockles treated in static seawater with single phage suspensions and phage cocktail phSE-2/phSE-5, similar decreases in cultivable bacteria concentration (~ 0.7–0.9 log CFU/g) were achieved after 6 h of treatment. When artificially contaminated cockles were depurated with phage phSE-5 in a recirculated seawater system (mimicking industrial depuration conditions), a 0.9 and 2.0 log CFU/g reduction of Salmonella spp. was reached after 4 and 6 h treatment. Once the depuration process was performed without phage, a 6 h treatment was needed to obtain a 1.1 log CFU/g reduction of Salmonella spp. Results indicated that combining phage biocontrol with depuration procedures enhance bivalve microbial safety for human consumption by improving decontamination efficiency, proving that this technology can be transposed to the bivalves industry. Moreover, this approach also displays the advantage of reducing the time required for depuration and consequently its associated costs.     

Antibacterial activities and membrane permeability actions of glycinin basic peptide against Escherichia coli

The objective of this study was to determine the antibacterial characteristics of glycinin basic peptide (GBP) and its effects on the cell membrane of Escherichia coli (E. coli). The antibacterial activities of GBP increased with increasing GBP concentrations and treatment times. Atomic force microscope analysis showed that GBP damaged the morphology of E. coli cells. GBP significantly (p < 0.05) increased the permeability of the outer membrane of E. coli cells treated with 80 μg/ml GBP, thereby enhancing the sensitivity of E. coli cells to erythromycin and rifampicin. Moreover, O-nitrophenyl-β-D-galactopyranoside (ONPG) entered into bacterial cells and immediately reacted with β-galactosidase in the cells due to the destruction of the inner membrane of E. coli. The damage to the bacterial membrane caused by GBP resulted in Ca^2 +, K⁺, and Mg^2 + leakage from the cells. SDS–PAGE of the membrane proteins further demonstrated that GBP significantly destroyed the cell membrane and promoted the extraction of membrane proteins in the presence of Triton X-114.Industrial relevanceIn recent years, chemical synthetic preservatives have aroused wide public concern because of various negative effects on human health. Novel natural food preservatives have received increasing interest from the food industry and researchers. The results of this study indicate that the antibacterial actions of GBP against E. coli occurred via interacting with destroying the bacterial membrane structure. Therefore, GBP may be a potential natural food preservative used in the food industry.     

Macro- and microelement contents in fruiting bodies of wild mushrooms from the Notecka forest in west-central Poland

Fruiting bodies of wild mushrooms and forest soil samples were collected and analyzed for macro- (N, P, K, S, Ca, Mg) and microelement (Al, Zn, Fe, Mn, Cd, Pb) contents in pine stands of the Notecka Forest in west-central Poland. Elements were determined by atomic absorption spectrometry in 160 samples of 8 fungal species and 15 underlying soil samples. Macro- and microelement contents in soil were low and characteristic of the poor and acidic sandy soils of the Polish lowlands not influenced by industrial pollution. In fruiting bodies, the highest mean concentration of macroelements (dry mass basis) was found for N (40.0 g kg⁻¹), followed by K (33.0 g kg⁻¹), P (5.4 g kg⁻¹), S (2.2 g kg⁻¹), Ca (1.0 g kg⁻¹) and Mg (0.7 g kg⁻¹). All macroelements (except for Ca) were concentrated in considerably higher levels in the fruiting bodies than in the forest soil. Nitrogen, P, K, S and Mg were preferably translocated into the cap rather than the stipes. Calcium, however, was often found in higher concentration in stipes than in caps. The mean microelement concentrations, across all tested fungi, were in the following order: Al > Zn > Fe > Mn > Pb > Cd. Microelements showed different distributions, depending on the part of the fruiting body. Some were more concentrated in the caps and some in stipes and distributions varied among species. Xerocomus badius is the most often harvested edible mushroom in the Notecka Forest. Pb and Cd distributions in fruiting bodies of this mushroom were evaluated in order to assess health risks to consumers. The estimated dietary exposures to Pb and Cd for consumers of this mushroom were in excess of guidelines on safe exposures.     

High hydrostatic pressure effects on mold flora,citrinin mycotoxin,hydroxytyrosol, oleuropein phenolics and antioxidant activity of black table olives

High hydrostatic pressure (HHP) as a non-thermal technology is an effective tool for microbiologically safe and shelf-stable fruits. Mycotoxin citrinin (CIT) is a toxic secondary metabolite, especially produced from filamentous fungus Penicillium citrinum and is also produced by other species of Penicillium, Aspergillus, and Monascus that are able to develop on olive after harvest, during brine and storage of olives. Nutritional benefits of olive fruit are mainly related to phenolics such as hydroxytyrosol, oleuropein and antioxidative effects. With HHP application of olives, total mold was reduced to 90% at 25 °C whereas it was 100% at 4 °C based on Rose-Bengal Chloramphenicol Agar (RBCA). Total Aerobic-Mesofilic Bacteria load was reduced to 35–76% at 35 ± 2 °C based on the Plate Count Agar (PCA). Citrinin load was reduced to 64–100% at 35 ± 2 °C. 2.5; 10; 25; and 100 ppb of spiked citrinin in sample were degraded as %56; %37; %9; and %1.3, respectively. 2.5 ppb and less citrinin contamination in table olive were degraded more (56%). Total phenolics were increased to 2.1–2.5-fold after HHP (as mgGA/100 g). Hydroxytyrosol in olives increased on average 0.8–2.0-fold whereas oleuropein decreased on average 1–1.2-fold after HHP (as mg/kg dwt). Antioxidant activity values varied from 17.238 to 29.344 mmol Fe²⁺/100 g for control samples whereas 18.579–32.998 mmol Fe²⁺/100 g for HHP-treated samples. HHP could be used in the olive industry as non-thermal preservation.     

Effect of preheating temperature and calcium ions on the properties of cold-set soybean protein gel

To elucidate the effect of preheating temperature and calcium ions on the properties of cold-set soybean protein gel, Ca²⁺ induced gelation of soybean protein were investigated by rheological approaches, electrophoresis analysis, confocal scanning laser microscopy (CSLM) and surface hydrophobicity (S₀). The results showed that, both CaCl₂ concentration (20–40 mM) and preheating temperature (80–120 °C) took significant influence on the dynamic viscoelasticity of the gel samples. The bands distribution of samples preheated at 120 °C were different from the bands distribution of samples preheated below 100 °C in denature and native electrophoresis. The CSLM analysis showed that the gel became coarser as the Ca²⁺ increased. On the other hand, two different kinds of gel were shown under the same Ca²⁺ concentration: a bead-like structure (below 100 °C) and a filamentous structure (above 100 °C). According to fractal theory, weak-linked gel (α was >0.8) was formed when preheating below 100 °C, while a transition gel (α = 0.52–0.62) was obtained when preheating over 100 °C. All these results suggested that the preheating temperature influence the type of cold-set gel.     

High-pressure calorimetric evaluation of ice crystal ratio formed by rapid depressurization during pressure-shift freezing of water and pork muscle

The amount of ice nuclei formed during the pressure release is important for the final formation and development of ice crystals in pressure shift freezing (PSF) frozen products. In this study, a high-pressure (HP) calorimeter was used to evaluate the ratio of ice crystals instantaneously formed by rapid depressurization during PSF of pure water and pork muscle tissue. Experiments were carried out initial pressure levels of 62, 115, 157 and 199 MPa, with corresponding phase change temperatures of −5, −10, −15 and −20 °C, respectively (slightly higher than phase change point of water–ice I). The ice crystal ratio was determined based on calorimetric peak measured and heat balance. The evaluated regression relationship between observed ice crystal ratio (R_ice in %) and pressure (P, MPa) was R_ice–water = 0.115P + 0.00013P² (R² = 0.96, n = 9) for pure water, and R_ice–pork = 0.080P + 0.00012P² (R² = 0.95, n = 11) for pork muscle. Compared to other methods, the calorimetric evaluation does not require any of the pressure-related properties of the test sample. HP calorimetry can thus be used to evaluate ice crystal ratio for PSF of foods even though their pressure related properties may be unknown.     

Antibiotic resistance and susceptibility to some food preservative measures of spoilage and pathogenic micro-organisms from spices

Antibiogram of 84 strains of Bacillus cereus, 26 strains of Clostridium perfringens, four strains of Staphylococcus aureus, 51 strains of Enterobacteriaceae, two strains of each of Salmonella and Shigella; isolated from spices, were studied against 20 different antibiotics that are commonly used against foodborne diseases, mainly gastroenteritis. All the tested strains of B. cereus, Cl. perfringens, Staph. aureus, Escherichia coli, Salmonella and Shigella were found resistant to at least 3, 4, 7, 6, 10 and 9 antibiotics, respectively. In brain–heart infusion broth supplemented with glucose, the D_100°C-values for B. cereus were 3.5–5.9 min, and the z-values were 17–18°C. The D_100°C-values for Cl. perfringens in fluid thioglycolate medium were higher (10.0–19.8 min) than those of B. cereus. The minimum inhibitory concentrations (MICs) of sodium chloride were 45–80 mg ml⁻¹. While the MIC of benzoic acid for Cl. perfringens, tested on perfringens agar (pH 7.3) plates by incubating anaerobially at 35°C for 24 h, was 1.9–2.2 mg ml⁻¹, for others, tested on nutrient agar (pH 6.8) plates by incubating at 35°C for 18 h in static aerobic condition, it was much less. Similarly, the MIC of sorbic acid for all the tested isolates, excepting Cl. perfringens, was 0.6–1.1 mg ml⁻¹. Of the eight isolates of Cl. perfringens, only three were inhibited at 2.0 mg sorbic acid ml⁻¹, while others were resistant. Sixty percent and 75% of the respective strains of B. cereus and Cl. perfringens were resistant to 5000 IU Nisaplin ml⁻¹, whereas the MIC values of Staph. aureus were between 3000 and 5000 IU ml⁻¹. While studying combined effect of selected hurdles on the growth of enterotoxigenic Cl. perfringens 16-C2, the judicious combination considered was low acid (pH 6.0), 30 mg sodium chloride ml⁻¹ and 1.25 mg benzoic acid ml⁻¹.     

Antimicrobial activity of pediocin-producing Lactococcus lactis on Listeria monocytogenes,Staphylococcus aureus and Escherichia coli O157:H7 in cheese

The antimicrobial activity of two pediocin-producing transformants obtained from wild strains of Lactococcus lactis on the survival of Listeria monocytogenes, Staphylococcus aureus and Escherichia coli O157:H7 during cheese ripening was investigated. Cheeses were manufactured from milk inoculated with the three pathogens, each at approximately 6 log cfu mL⁻¹. Pediococcus acidilactici 347 (Ped⁺), Lc. lactis ESI 153, Lc. lactis ESI 515 (Nis⁺) and their respective pediocin-producing transformants Lc. lactis CL1 (Ped⁺) and Lc. lactis CL2 (Nis⁺, Ped⁺) were added at 1% as adjuncts to the starter culture. After 30 d, L. monocytogenes, S. aureus and E. coli O157:H7 counts were 5.30, 5.16 and 4.14 log cfu g⁻¹ in control cheese made without adjunct culture. On day 30, pediocin-producing derivatives Lc. lactis CL1 and Lc. lactis CL2 lowered L. monocytogenes counts by 2.97 and 1.64 log units, S. aureus by 0.98 and 0.40 log units, and E. coli O157:H7 by 0.84 and 1.69 log units with respect to control cheese. All cheeses made with nisin-producing LAB exhibited bacteriocin activity throughout ripening. Pediocin activity was only detected throughout the whole ripening period in cheese with Lc. lactis CL1. Because of the antimicrobial activity of pediocin PA-1, its production in situ by strains of LAB growing efficiently in milk would extend the application of this bacteriocin in cheese manufacture.     

Growth-inhibition of hiochi bacteria in namazake (raw sake) by bacteriocins from lactic acid bacteria

The bacteriocins produced by Lactococcus lactis subsp. lactis C101910 (C101910) and NBRC 12007 (NBRC 12007) were used to prevent the growth of sake spoiling hiochi bacteria (Lactobacillus hilgardii, Lactobacillus fructivorans, and Lactobacillus paracasei) in namazake, which is raw (unpasteurized) sake. The bacteriocin concentrations required for decreasing the viable cell concentrations of L. hilgardii and L. fructivorans below the detection limit (1.0 × 10² cells/ml) in 24 h from the initial concentration of 4.0–9.5 × 10⁵ cells/ml in the namazake at pH 4.5 and at 4°C, were 18–35 U/ml and 5.6 U/ml for the bacteriocin from C101910 and NBRC 12007, respectively. To decrease the viable cell concentration of L. paracasei from the initial concentration of 7.5 × 10⁵ cells/ml to below the detection limit (1.0 × 10² cells/ml) in 24 h, 350 U/ml bacteriocin from C101910 and 140 U/ml bacteriocin from NBRC 12007 were required. In experiments using McIlvaine buffer (pH 4.5) with 15% ethanol instead of namazake as the medium, the viable cell concentrations of L. hilgardii and L. paracasei decreased to less than 1.0 × 10² cells/ml, whereas those of L. fructivorans decreased to less than 1.0 × 10³ cells/ml, when bacteriocins were added at the concentrations that had proven effective in namazake. The membrane depolarization assay using a fluorescent probe showed that the presence of ethanol stimulated the collapse of the membrane potential induced by bacteriocins. The ethanol induced collapse of the membrane potential suggests that the application of bacteriocins at the storage stage of namazake is more beneficial than when used in other stages of the sake brewing process.     

Dual-enzymatic synthesis of lactulose in organic-aqueous two-phase media

Lactulose has been successfully synthesized by dual-enzymatic method in organic-aqueous two-phase media using lactose and fructose as the raw materials. Cyclohexane–buffer system C₆H₁₂:buffer = 95:5 (v/v) was employed as the organic-aqueous media for the reaction. The dual-enzymatic system was consisted of immobilized lactase (IL) and immobilized glucose isomerase (IGI). Immobilized lactase was prepared by cross-linking the free lactase into Fe₃O₄-chitosan magnetic microspheres. The main enzymatic reaction parameters were investigated, including reaction temperature (T), pH value and reaction time (t). Under the optimum reaction conditions, i.e., lactose 0.8 g mL^?1, fructose 0.1 g mL^?1, IL 0.1 g mL^?1, IGI 0.05 g mL^?1, T = 30 °C, pH = 8.0 and t = 2 h, the obtained highest lactulose yield was approximately 151 g L^?1 and the corresponding productivity was 75.5 g L^?1 h^?1. Experimental results indicated that the organic-aqueous media can significantly promoted the transglycosidation activity of lactase and therefore improve the lactulose yield. The possible reaction mechanism of the synthesis of lactulose using IL and IGI in two-phase system was also proposed.     

Biochemical characterisation of an aminopeptidase with highest preference for lysine from Japanese flounder skeletal muscle

An aminopeptidase was purified from Japanese flounder skeletal muscle to homogeneity by ammonium sulphate fractionation and three chromatographies. The enzyme was approximately 100 kDa with isoelectric point of 5.7 as estimated by two-dimensional polyacrylamide gel electrophoresis. Its optimum temperature and pH were 45 °C and 7.5, respectively. According to peptide mass fingerprinting study, the enzyme revealed high identity to a puromycin-sensitive aminopeptidase. It had a broad specificity toward aminopeptidase substrates and preferred to hydrolyse Lys-MCA with k_cat/K_m of 8.1 × 10⁶ M^?1 s^?1, and the activation energy (E_a) of 72.5 kJ M^?1. Metal-chelating agents effectively inhibited the enzyme activity, and Zn²⁺, Mn²⁺ and Co²⁺ significantly restored the apoenzymatic activity dialysed by EDTA, whilst inhibitors to other proteinases did not show much effect. Furthermore, bestatin strongly inhibited its activity. These results indicate that the purified enzyme is a metalloaminopeptidase which would possibly contribute to free amino acids increase in fish muscle.     

Immunoglobulins,growth factors and growth hormone in bovine colostrum and the effects of processing

In colostrum collected 0–80 h postpartum the contents of immunoglobulins (Igs), transforming growth factor beta-2 (TGF-β2), insulin-like growth factor-1 (IGF-1) and growth hormone (GH) were analysed. Colostrum initially contained 90 mg mL⁻¹ IgG1, 2.8 mg mL⁻¹ IgG2, 1.6 mg mL⁻¹ IgA, 4.5 mg mL⁻¹ IgM, and these concentrations declined by 92%, 87%, 93% and 84%, respectively, in the samples collected later. Of the growth factors, colostrum initially contained 289–310 ng mL⁻¹ TGF-β2 and the concentration diminished to 66 ng mL⁻¹. The content of IGF-1 and GH postpartum decreased from 870 to 150 ng mL⁻¹, and from 0.17 to <0.03 ng mL⁻¹, respectively. Heat treatment and freeze-drying of colostral whey decreased the content of Igs to 75%, while the contents of IGF-1 and TGF-β2 were unaffected. A similar processing, including filtration steps reduced also the IGF-1 and TGF-β2 by 25%. IgM seems to be the most sensitive of the Igs to processing.     

Compositional and thermal characteristics of palm olein-based diacylglycerol in blends with palm super olein

Palm olein-based diacylglycerol (POL-DAG) was blended with palm super olein (POoo) in various concentrations (10–90%), with increments of 10% (wt/wt) POL-DAG. The physical and chemical characteristics, i.e., iodine value, acylglycerol content, fatty acid composition, melting and crystallization profiles and solid fat content, for POL-DAG, POoo and their binary blends were evaluated. The mid-infrared FTIR was used to determine the absorption bands of the different concentrations of the oil blends. Only slight differences of FAC and IV were observed. POL-DAG:POoo blends showed significant changes (p < 0.05) in DAG content and decreases in TAG content with increasing POL-DAG content. The DSC thermograms showed that the addition of different concentrations of POL-DAG changed the melting and crystallization behavior of the oil blends (POL-DAG:POoo). The crystallization onset point increased (p < 0.05) with an increasing POL-DAG concentration (10–90%). POL-DAG has the same absorption bands as POoo, with the exception of several minor peaks that appeared at (I) 2954 cm^− 1, (II) 1267 cm^− 1, (III) 1199 cm^− 1, (IV) 1222 cm^− 1 and (V) 966 cm^− 1. This study will provide essential information for the palm oil industry to identify the most suitable POL-DAG blends with desirable physicochemical properties for food application purposes.     

Ionic liquid-based ultrasound-assisted surfactant-emulsified microextraction for simultaneous determination of three important flavoring compounds in plant extracts and urine samples

For the first time, a novel, efficient and environmentally friendly method termed ionic liquid-based ultrasound-assisted surfactant-emulsified microextraction (IL-UA-SE-ME) was developed and compared with normal-, reversed-, surfactant assisted-dispersive liquid–liquid microextraction and ultrasound-assisted surfactant-based emulsification microextraction methods for the analysis of three bioactive and flavoring compounds (para-anisaldehyde, trans-anethole and its isomer estragole) in some fresh plants (fennel and basil), their extracts and urine samples. The results showed that IL-UA-SE-ME is a much more effective method and under the optimum conditions (including extraction solvent: 90 μL of [C₆MIM][PF₆]; disperser: 5 mg of N-dodecylbenzenesulfonic acid sodium salt; sample pH: 3; sonication time: 5 min; and centrifuging time: 5 min), limits of detection, limits of quantification, linear ranges, recoveries, and enrichment factors were in the range of 16–22 ng mL^− 1, 49–67 ng mL^− 1, 0.04–90 μg mL^− 1, 94.3%–101.1%, and 118–127, respectively.     

Adsorption kinetics,thermodynamics and isotherm of Hg(II) from aqueous solutions using buckwheat hulls from Jiaodong of China

The adsorption kinetics and adsorption isotherms of buckwheat hulls in the region of Jiaodong, China (BHJC) for Hg(II) were investigated. Results revealed that the adsorption kinetics of BHJC for Hg(II) were well described by a pseudo second-order reaction model, and the adsorption thermodynamic parameters ΔG, ΔH and ΔS were –5.83 kJ mol^?1(35 °C), 73.1, and 256 J K^?1 mol^?1, respectively. Moreover, Langmuir, Freundlich and Redlich–Peterson isotherm models were applied to analyse the experimental data and to predict the relevant isotherm parameters. The best interpretation for the experimental data was given by the Langmuir isotherm equation, and the maximum adsorption capacity for Hg(II) is 243.90 mg/g at 35 °C. Furthermore, investigation of the adsorption selectivity showed that BHJC displayed strong affinity for mercury in the aqueous solutions and exhibited 100% selectivity for mercury in the presence of Zn(II) and Cd(II).     

Effect of ozone on microbial,chemical and sensory attributes of shucked mussels

The effect of ozonation in aqueous solution (O₃ concentration=1 mg/l, time of ozonation: 60 and 90 min) on the shelf-life of shucked, vacuum-packaged mussels, stored under refrigeration was studied by monitoring the microbiological, chemical and sensory changes occurring in mussel samples, for a period of 12 days. Non-ozonated vacuum-packaged mussels served as the control sample. Ozonation affected populations of bacteria namely, aerobic plate count (APC) (0.7–2.1 log cycle reduction), Pseudomonas spp. (0.5–1.1 log cycle reduction) and H₂S-producing bacteria (1.1–2.5 log cycle reduction), Brochothrix thermosphacta (0.3–1.4 log cycle reduction), lactic acid bacteria (0.3–0.8 log cycle reduction) and Enterobacteriaceae (0.5–1.5 log cycle reduction). The effect of ozonation was more pronounced at the longer time of ozonation. Of the chemical indicators of spoilage monitored, trimethylamine values of all mussel samples remained relatively low throughout the entire storage period, attaining values of 7.5, 6.0 and 6.4 mg N/100 g for the control and ozonated for 60 and 90 min samples, respectively, on day 12 of storage. Total volatile basic nitrogen (TVB-N) values similarly remained relatively low (⩽20 mg N/100 g) until day 6 of storage, and increased to 31.9, 24.2 and 26.9 mg N/100 g mussel meat for the control and ozonated for 60 and 90 min samples, respectively, on day 12 of storage. Initial TBA values were surprisingly high (30–35 mg MA/kg) and decreased to 23.0, 21.7 and 13.3 mg MA/kg mussel meat on day 12 of storage for the control and the ozonated for 60 and 90 min samples, respectively. Sensory evaluation (odor, taste and texture) of cooked mussels showed a good correlation with bacterial populations. On the basis of sensory analyses, a shelf-life of 12 days was obtained for vacuum-packaged mussels ozonated for 90 min as compared to a shelf-life of 9 days for the control sample.     

Degradation of various fruit juice anthocyanins by hydrogen peroxide

Degradation kinetics of anthocyanins was studied in sour cherry nectar, pomegranate and strawberry juices at high hydrogen peroxide (H₂O₂) concentrations (9.31–27.92 mmol l⁻¹) at 10–30 °C and in only sour cherry nectar at low H₂O₂ concentrations (0.23–2.33 mmol l⁻¹) at 20 °C. Degradation of anthocyanins followed the first-order reaction kinetics. Sour cherry anthocyanins were the most resistant to H₂O₂, followed by pomegranate and strawberry anthocyanins. Degradation of anthocyanins was also studied in sour cherry nectar and pomegranate juice in the presence of ascorbic acid at 60 and 80 mg l⁻¹ concentrations at 20 °C. At 80 mg level, ascorbic acid significantly accelerated the degradation of anthocyanins in sour cherry nectar at 4.65, 6.98 and 9.31 mmol l⁻¹ H₂O₂ concentrations. In contrast, ascorbic acid at both 60 and 80 mg levels protected the anthocyanins from degradation by H₂O₂ in pomegranate juice.