Antibacterial activity of zinc oxide nanoparticle suspensions on food‐borne pathogens

Nanoparticles (NPs) are increasingly recognised for their utility in biological applications including nanomedicine and food safety. The present study investigated the antibacterial activity of zinc oxide (ZnO) when tested against the Gram‐negative bacteria Escherichia coli as well as the Gram‐positive bacterium Staphylococcus aureus, and the effect was more pronounced with the Gram‐positive than with the Gram‐negative bacteria. ZnO NPs also exhibited a preferential ability to suppress growth of E. coli and S. aureus in milk. This study suggested that the application of ZnO NPs as antibacterial agents in food systems and medicine may be effective at inhibiting certain pathogens.     

Effect of different drying methods on chemical and molecular structure of heteropolysaccharide–protein gum from durian seed

The functional properties and biological aspects of a natural biodegradable biopolymer depend on its chemical and molecular structure. In this study, the effect of different drying processes on the chemical and molecular structure of the natural biodegradable biopolymer from durian seed was investigated. The chemical structure was analyzed by assessing the carbohydrate profile, protein, amino acid composition, moisture, and ash. Molecular weight (M_w), number average molecular weight (M_n), M_w/M_n ratio and mass recovery were assessed by using a size-exclusion chromatography coupled to multi angle laser light-scattering (SEC-MALS). The present study revealed that main monosaccharides in the chemical structure of differently dried durian seed gums were galactose (50.1–64.9%), glucose (29.4–45.7%%), arabinose (0.11–0.89%), and xylose (0.019–0.86%). The protein analysis indicated the presence of a low amount of the protein fraction (3.2–3.9%) in the chemical structure of the biopolymer from durian seed. The most abundant amino acids in the chemical structure of durian seed gum were leucine (31.78–43.02%), lysine (6.23–7.78%), aspartic acid (6.45–8.58%), glycine (6.17–7.27%), glutamic acid (5.43–6.55%), alanine (4.60–6.23%), and valine (4.49–5.52). The current study exhibited that the biodegradable biopolymer from durian seed was a heteropolysaccharideprotein complex with medium M_w ranging from 1.06 × 10⁵ to 1.15 × 10⁵ (g/mol).     

Effect of glycerol and vegetable oil on physicochemical properties of Arabic gum-based beverage emulsion

The effect of two emulsion components namely glycerol (0.5, 1 and 1.5% w/w) and vegetable oil (2, 3 and 4% w/w) on ζ-potential, conductivity, pH, apparent viscosity, fluid behavior, turbidity and cloud stability of orange beverage emulsion was investigated. The negatively charged ζ-potential significantly (p < 0.05) increased with increasing glycerol content. A slight increase in ζ-potential was observed by adding 2% (w/w) vegetable oil to the emulsion formulation, while it was slightly decreased when vegetable oil content was increased up to 4% (w/w). Apparent viscosity, pH and turbidity of orange beverage emulsions significantly (p < 0.05) increased when the concentration of glycerol or vegetable oil was increased. All prepared beverage emulsions behaved as non-Newtonian (i.e., pseudoplastic or shear thinning) fluids. The addition of different concentration levels of both supplementary emulsion components except for 0.5% (w/w) glycerol significantly (p < 0.05) improved the cloud stability of orange beverage emulsions.     

Effect of absorbent in solid‐phase extraction on quantification of phospholipids in palm‐pressed fiber

Palm‐pressed fiber (PPF) is a by‐product of palm oil milling and it has been found to contain a high percentage of phospholipids (PL). The aim of this work was to evaluate the best solid‐phase extraction (SPE) method to purify PL from PPF. The purified PL were analyzed using high‐performance liquid chromatography (HPLC) with an evaporative light‐scattering detector (ELSD). The oil was extracted from PPF using the Folch method and classes of PL were purified using SPE. Different solvent phases and normal‐phase SPE cartridges [silica (Si), aminopropyl‐bonded silica (NH₂) and diol‐bonded silica (2OH)] at the same ratio of oil to sorbent mass were used to study the separation of PL from the extracted oil. The recovery of each standard PL was performed in a model oil system with the same amount of standard PL being added, and the repeatability of the SPE method was investigated. The isolation of PL by SPE diol cartridge and subsequent analysis by HPLC/ELSD have shown to be an accurate and reproducible analytical method for the determination of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and lysophosphatidylcholine in PPF. This method provided a high yield and rapid separation of PL in PPF with less contamination from other lipid groups.     

Analysis of structures transformable to circulant form using U-transformation and Kronecker products

In this paper, eigenvalues and eigenvectors of the specific types of structural matrices are studied, and a simple method is presented for calculating their eigenvalues. First, the required formulation to diagonalize circulant and block circulant matrices is presented by using U-matrix transformation. Then utilizing the method of this paper, matrices with non-circulant forms are converted into their circulant counterpart matrices. In order to demonstrate the efficiency of the method, some examples are provided using numerical methods such as finite differences, finite element and finite stripe methods.     

Equilibrium headspace analysis of volatile flavor compounds extracted from soursop (Annona muricata) using solid-phase microextraction

The influence of headspace solid-phase microextraction (HS-SPME) variables, namely, sample concentration, salt concentration and sample amount, on the equilibrium headspace analysis of the main volatile flavor compounds released from soursop was investigated. A total of 35 volatile compounds, comprising 19 esters, six alcohols, three terpenes, two acids, two aromatics, two ketones and an aldehyde, were identified. The results indicated that all response-surface models were significantly (p < 0.05) fitted for 10 target volatile flavor compounds. The results further indicated that more than 65% of the variation in the equilibrium headspace concentrations of target volatile flavor compounds could be explained by the final reduced models, with high R² values ranging from 0.658 to 0.944. Multiple optimization results showed that extraction using a 76.6% (w/w) sample concentration, 20.2% (w/w) salt and 8.2 g of blended soursop pulp was predicted to provide the highest overall equilibrium headspace concentration for the target soursop volatile flavor compounds.     

Effect of Saturated/Unsaturated Fatty Acid Ratio on Physicochemical Properties of Palm Olein–Olive Oil Blend

Although blending polyunsaturated oil with more saturated or monounsaturated oils has been studied extensively, there is no similar information regarding the partial replacement of palm olein with olive oil (OO). Therefore the main objective of this study was to investigate the effects of OO partial replacement (0, 25, 50, 75, 90 and 100% w/w) on the chemical stability of palm olein oil (POO). The physicochemical properties of oil samples namely iodine value, peroxide value (PV), anisidine value, TOTOX value (total oxidation value, TV), free fatty acid (FFA), cloud point, color and viscosity were considered as response variables. Significant differences among the oil blend properties were determined at the significance level of P < 0.05. Apart from FFA, all the response variables were significantly influenced by type and concentration of oils. The oil blend containing 10% POO and 90% OO showed the highest TV (6.10); whereas the blend containing 90% POO and 10% OO exhibited the least TV (2.41). This study indicated that the chemical stability of oil blend significantly (P < 0.05) increased with increasing the proportion of polyunsaturated/monounsaturated fatty acid.     

Storage stability of jackfruit (Artocarpus heterophyllus) powder packaged in aluminium laminated polyethylene and metallized co-extruded biaxially oriented polypropylene during storage

Total colour difference (ΔE), rates of adsorbed moisture and sensory attributes of drum-dried jackfruit powder packaged in aluminium laminated polyethylene (ALP) and metallized co-extruded biaxially oriented polypropylene (BOPP/MCPP) pouches stored at accelerated storage (38 °C, with 50%, 75% and 90% relative humidity (RH)) were determined over 12 weeks period. The changes in total colour followed zero order reaction kinetics. Packaging materials, storage temperature and RH values significantly (p < 0.05) influenced the rates of adsorbed moisture of jackfruit powder. There was a significant (p < 0.05) decrease in the intensities of the fruity odour, taste and increase in the lumpiness of the jackfruit powder stored at 38 °C with 90% RH. The shelf life of jackfruit powder stored at 38 °C and 90% RH was limited by overall acceptability and the intensity of fruity odour, taste and lumpiness at week 8 of storage. Jackfruit powder stored at 28 °C remained stable and acceptable throughout the storage period for all RH values. The powder packaged in ALP significantly (p < 0.05) reduced total colour change, rates of adsorbed moisture, lumpiness intensity of jackfruit powder and was rated higher in terms of overall acceptability over BOPP/MCPP. Results of this study suggested that ALP packaging with storage conditions of 28 °C and RH less than 75% was better suited for keeping jackfruit powder.     

Solid-phase microextraction for headspace analysis of key volatile compounds in orange beverage emulsion

Headspace solid-phase microextraction (HS-SPME) gas chromatography was used to analyze target flavor compounds in orange beverage emulsion. The effects of SPME fiber (PDMS 100 μm, CAR/PDMS 75 μm, PDMS/DVB 65 μm and DVB/CAR/PDMS 50/30 μm), adsorption temperature (25–45 °C), adsorption time (5–25 min), sample concentration (1–100%), sample amount (5–12.5 g), pH (2.5–9.5), salt type (K₂CO₃, Na₂CO₃, NaCl and Na₂SO₄), salt amounts (0–30%) and stirring mode were studied to develop HS-SPME condition for obtaining the highest extraction efficiency and aroma recovery. For the head space volatile extraction, the optimum conditions were: CAR/PDMS fiber, adsorption at 45 °C for 15 min, 5 g of diluted beverage emulsion (1:100), 15% (w/w) of NaCl with stirring and original pH 4. The main volatile flavor compounds were: limonene, 94.9%; myrcene, 1.2%; ethyl butyrate, 1.1%; γ-terpinene, 0.41%; linalool, 0.36%; 3-carene, 0.16%; decanal, 0.12%; ethyl acetate, 0.1%; 1-octanol, 0.06%; geranial, 0.05%; β-pinene, 0.04%; octanal, 0.03%; α-pinene, 0.03%; and neral, 0.03%. The linearity was very good in the considered concentration ranges (R² ? 0.97). Average recoveries ranged from 88.3% to 121.7% and showed good accuracy for the proposed analytical method. Average relative standard deviation (RSD) for five replicate analyses was found to be less than 14%. The limit of detection (LOD) ranged from 0.06 to 2.27 mg/l for all volatile flavor compounds and confirmed the feasibility of the HS-SPME technique for headspace analysis of orange beverage emulsion. The method was successfully applied for headspace analysis of five commercial orange beverage emulsions.     

Feasibility study of wind energy potential in two provinces of Iran: North and South Khorasan

In this study, the measured wind speed data for year 2007 at 10 m, 30 m and 40 m heights for two provinces of Iran, North and South Khorasan, have been statistically analyzed to determine the potential of wind power generation. This paper presents the wind energy potential at four zones in these provinces, Bojnourd, Esfarayen of North Khorasan province and Nehbandan, and Fadashk of South Khorasan province. The objective is to evaluate the most important characteristic of wind energy in the studied sites. The statistical attitudes permit us to estimate the mean wind speed, the wind speed distribution function, the mean wind power density in the sites at the height of 10 m, 30 m and 40 m. Also, three new types of wind rose diagrams were shown.