Evaluation of Protease-producing Ability of Fish Gut Isolate Bacillus cereus for Aqua Feed

Extracellular protease production by Bacillus cereus isolated from the intestine of fish Mugil cephalus has been investigated in shake-flask experiment using different preparations of tuna-processing waste such as raw fish meat, defatted fish meat, alkali hydrolysate, and acid hydrolysate as nitrogen source. Among the tuna preparations tested, defatted fish meat supported the maximum protease production (134.57 ± 0.47 U ml⁻¹), and 3% concentration of the same was found to be optimum for maximizing the protease production (178.50 ± 0.28 U ml⁻¹). Effect of carbon sources on protease production in the optimized concentration of defatted tuna fish meat revealed that galactose aided the higher protease production (259.83 ± 0.04 U ml^–1) than the other tested carbon sources and a concentration of 1.5% galactose registered as optimum to enhance the protease production (289.40 ± 0.16 U ml⁻¹). The halotolerancy of B. cereus for protease production indicated that 3% of sodium chloride was optimum to yield maximum protease (301.63 ± 0.20 U ml⁻¹). Among the surfactants tested, protease production was high in Triton X 100-added medium (298.63 ± 0.12 U ml⁻¹) when compared to other surfactants, and its optimum concentration recorded was 0.8% (320.57 ± 0.17 U ml⁻¹) for more protease production. Partial characterization of crude enzyme revealed that pH 7.0 (278.90 ± 0.08 U ml⁻¹) and 60°C temperature (332.37 ± 0.18 U ml⁻¹) were optimum for better protease activity by B. cereus.     

Stability and Degradation Kinetics of Bioactive Compounds and Colour in Strawberry Jam during Storage

The effect of storage time and temperature on degradation of bioactive compounds such as ascorbic acid, anthocyanins, total phenols, colour and total antioxidant capacity of strawberry jam were investigated. The results indicated that lightness (L) value decreased significantly (p < 0.05) over 28 days of storage at 4 and 15 °C, with lower values measured at higher temperatures. Anthocyanins, ascorbic acid and colour degradation followed first-order kinetics where the rate constant increased with an increase in the temperature. The reaction rate constant (k) increased from 0.95 × 10⁻² day⁻¹ to 1.71 × 10⁻² day⁻¹ at 4 and 15 °C for anthocyanins. Similarly, k increased from 2.08 × 10⁻² day⁻¹ to 4.54 × 10⁻² day⁻¹ at 4 and 15 °C for ascorbic acid. In general, total antioxidant activity for strawberry jam samples stored for 28 days at 4 and 15 °C exhibited lower values as compared to control (day 0). The results showed greater stability of nutritional parameters at 4 °C compared to 15 °C.     

Determination of Rosmarinic Acid by High-Performance Liquid Chromatography and Its Application to Certain Salvia Species and Rosemary

This study describes a method development for the determination of rosmarinic acid (RA) by using a gradient high-performance liquid chromatography (HPLC) and its application to certain plant materials. The analysis was performed by utilizing a two solvents system [A: methanol/water/formic acid (10:88:2; v:v:v); B: methanol/water/formic acid (90:8:2; v:v:v)] on a reverse-phase column. The flow rate and injection volume were 1 ml min⁻¹ and 10 μl, respectively. Signals were detected at 280 nm. In addition, an internal standard (IS) technique was applied for the analysis of RA to increase precision, and propylparaben was employed for this purpose. The repeatability results as RSD% were 1.66, 1.17 and 1.26 for intra-day and 1.38 was for inter-day with the employment of (3.67 × 10⁻⁵ M) RA. A limit of linearity (LOL) was observed in a wide (1.13 × 10⁻⁵–5.65 × 10⁻⁴ M) concentration range. Linearity parameters were also examined in the range of 5.95 × 10⁻⁶–7.14 × 10⁻⁵ M RA, and very good correlation was observed. The limit of detection (LOD) and limit of quantification (LOQ) (for inter-day) were 1.60 × 10⁻⁶ M (signal/noise [S/N] = 3.3) and 4.80 × 10⁻⁶ M (S/N = 10), respectively. The method was applied to the extracts of certain Lamiaceae plants (Salvia candidissima Vahl. subsp. candidissima, S. sclarea L., S. verticillata L. subsp. verticillata and R. officinalis L.), and reasonable results were obtained.     

Application of Catalytic Hydrogen Evolution in the Presence of Neonicotinoid Insecticide Clothianidin

Clothianidin, a new generation of pesticide, was determined in spiked tap water, apple juice, and soil by square-wave adsorptive stripping voltammetry. The method of determination is based on the hydrogen evolution reaction catalyzed by clothianidin at the hanging mercury drop electrode. The optimal signal was detected at −1.4 V versus Ag/AgCl in citrate buffer at pH 2.2. Various parameters such as pH, buffer concentration, frequency, amplitude, step potential, accumulation time, and potential were investigated to enhance the sensitivity of the determination. The optimal results were recorded at an accumulation potential of −0.35 V, accumulation time of 7 s, amplitude of 100 mV, frequency of 200 Hz, and step potential of 7 mV. The mechanism of catalytic hydrogen evolution was considered under experimental and theoretical conditions. This electroanalytical procedure enabled to determine clothianidin in the concentration range 9 × 10⁻⁹–4 × 10⁻⁶ mol L⁻¹ in supporting electrolyte and tap water, 1 × 10⁻⁷–4 × 10⁻⁶ mol L⁻¹ in diluted apple juice, and 2 × 10⁻⁷–1 × 10⁻⁶ mol L⁻¹ in soil. The detection and quantification limits in supporting electrolyte and diluted apple juice were found to be 2.6 × 10⁻⁹, 8.6 × 10⁻⁹ and 3 × 10⁻⁸, and 1 × 10⁻⁷ mol L⁻¹, respectively. A standard addition method was successfully used to determine clothianidin in spiked tap water, spiked apple juice, and spiked soil.     

Influence of Ultrasound on Freezing Rate of Immersion-frozen Apples

The use of power ultrasound within the food industry is an innovative subject. Application of sound to monitor a process or product is common, e.g. in quality assurance. However, the use of ultrasound to directly improve processes and products is less popular in food manufacturing. In the present work, ultrasound-assisted immersion freezing was investigated on apple samples. Because the apple parenchyma is mechanically anisotropic, the influence of applying ultrasound on radial or tangential orientated samples was also examined. Apple cylinders were immersed in an ultrasonic bath system, which operates at 40 kHz frequency. Experiments were carried out at a power level of 131.3 W (0.23 W/cm²), and ultrasound was applied intermittently for different times from temperatures below and close to the initial freezing point. Results showed that ultrasound application at 0°C or −1°C for 120 s in total, with 30 s intervals, significantly improved the freezing rate represented by the characteristic freezing time up to 8% (P < 0.05), compared to immersion freezing without ultrasound. Results of the effect of ultrasound waves applied on radial or tangential cut samples sonicated for 120 s from −1°C and/or 0°C indicated that at the power level considered there were no significant differences among the ultrasonic radial or tangential irradiated samples of these treatments, though the freezing rates were enhanced and different (P < 0.05) from the control treatment. Some evidence of the influence of ultrasound to induce primary nucleation was also observed.     

Shelf Life of Pretreated Dried Tomato

Determining the shelf life has become a factor of major importance in the development of foods designed to meet consumer demands in terms of quality and safety. The goal of the present study was to investigate the shelf life of vacuum-packed dried tomatoes, stored at both room and refrigeration temperature (4 °C) for a period of 180 days. The following determinations were performed during the storage period studied: microbiological analysis, instrumental color, lycopene, and ascorbic acid. Sorption isotherms were determined at both temperatures (room temperature and 4 °C). The microbiological quality of vacuum-packed dried tomatoes remained unchanged during 180 days for the refrigerated samples and 90 days for the samples stored at room temperature. The rate constant (k) of lycopene degradation of the refrigerated samples and the samples stored at room temperature was 3.209 × 10⁻⁵ and 12.994 × 10⁻⁵/day, respectively. The rate constant (k) of ascorbic acid degradation was 3.339 × 10⁻⁴/day for cold storage and 76.655 × 10⁻⁴/day for storage at room temperature. The tomatoes stored at room temperature were subjected to analysis over 90 days of storage, period after which both the appearance and sensory characteristics of the product fell below the levels of consumer acceptability. As for the tomatoes stored at refrigeration temperature, the original sensory characteristics were maintained throughout the entire storage period of 180 days.     

Kinetics of Mass Transfer in Microwave Precooked and Deep-Fat Fried Ostrich Meat Plates

The aim of this study was to evaluate the effect of microwave precooking on mass transfer during deep-fat frying of ostrich meat plates. The influence of microwave power level, frying temperature, and time on mass transfer was determined. Among all treatments, the plates being precooked at 5.23 W/g of microwave power and then deep-fat fried at 135 °C had the minimum fat content. The effective moisture diffusivity ranged between 1.47 × 10⁻⁸ and 4.17 × 10⁻⁸ m²/s. Fat transfer rate constant was in the range of 0.024 and 19.708 s⁻¹. The activation energy obtained from Arrhenius plot for the effective moisture diffusivity ranged between 38.84 and 51.07 kJ/mol.     

Quenching of excited states of red-pigment zinc protoporphyrin IX by hemin and natural reductors in dry-cured hams

Zinc protoporphyrin IX (ZnPP), the major red pigment in hams dry-cured without nitrates/nitrites, is an efficient photosensitizer, which upon absorption of visible light forms short-lived excited singlet state (¹ZnPP*) and by intersystem crossing yields the very reactive triplet-excited state (³ZnPP*). Using nano-second laser flash photolysis and transient absorption spectroscopy NADH, ascorbic acid, hemin and dehydroascorbic acid were each found to be efficient quenchers of ³ZnPP*. The deactivation followed, in homogeneous dimethyl sulfoxide (DMSO) or DMSO:water (1:1) solutions, second-order kinetics. The rate constant for ascorbic acid and NADH for reductive quenching of ³ZnPP* was at 25 °C found to be 7.5 ± 0.1 × 10⁴ L mol⁻¹ s⁻¹ and 6.3 ± 0.1 × 10⁵ L mol⁻¹ s⁻¹, respectively. The polyphenols catechin and quercetin had no effect on ³ZnPP*. The quenching rate constant for oxidative deactivation of ³ZnPP* by dehydroascorbic acid and hemin was at 25 °C: 1.6 ± 0.1 × 10⁵ L mol⁻¹ s⁻¹ and 1.47 ± 0.1 × 10⁹ L mol⁻¹ s⁻¹, respectively. Oxidized glutathione did not act as an oxidative quencher for ³ZnPP*. After photoexcitation of ZnPP to ¹ZnPP*, fluorescence was only found to be quenched by the presence of hemin in a diffusion-controlled reaction. The efficient deactivation of ³ZnPP* and ¹ZnPP* by the metalloporphyrin (hemin) naturally present in meat may accordingly inherently protect meat proteins and lipids against ZnPP photosensitized oxidation.     

Effects of Lactic and Acetic Acid on Survival of Salmonella enteritidis During Refrigerated and Frozen Storage of Chicken Meats

Chicken leg and breast meat samples inoculated with Salmonella enteritidis [4–5 log most probable number (MPN)/cm²] were dipped into lactic acid (LA; 1% and 3%) and acetic acid (AA; 1% and 2%) solutions for 10 min. After packaging, samples were stored at 4 °C (10 days) or −18 °C (6 months). Immediately after dipping into 1% LA, 3% LA, 1% AA, and 2% AA solutions, S. enteritidis counts on leg meat samples were reduced by 0.75, 1.21, 0.85, and 0.95 log MPN/cm², while the reductions were 0.97, 1.72, 0.92, and 1.58 log MPN/cm² on breast meat samples, respectively. The differences between the water-washed control and the acid-treated groups for Salmonella counts were statistically significant (P < 0.05). Salmonella counts on leg meat samples treated with 1% LA, 1% AA, and 2% AA were reduced by 0.54–1.52 log MPN/cm² (P < 0.05) during storage at 4 °C. However, for the breast meat samples, only Salmonella counts of water-washed controls were significantly reduced during refrigerated storage (P < 0.05). S. enteritidis counts on organic acid-treated samples were reduced by 0.13–0.55 log MPN/cm² during storage at −18 °C for 6 months, while the reduction on the water-washed controls was 0.64 log MPN/cm². It can be concluded that lactic or acetic acid treatment could be useful especially for reducing the initial Salmonella contamination. On the other hand, this pathogen could survive on poultry meats during refrigerated and frozen storage even following lactic or acetic acid decontamination.     

Effect of Low Temperature Sonication on Orange Juice Quality Parameters using Response Surface Methodology

Freshly squeezed orange juice samples were sonicated at a constant frequency of 20 kHz for a range of processing temperatures (10–30 °C), amplitude levels (40–100%) and time (2–10 min) with pulse durations of 5 s on and 5 s off. Hunter colour values (L*, a* and b*), pH, ^oBrix, titratable acidity, cloud, non-enzymatic browning and ascorbic acid content were measured. Response surface methodology (RSM) based upon a three-factor, three-level Box–Behnken experimental design was used to determine the effect of independent variables. Under process conditions used in this study, no significant difference (p < 0.05) in pH, ^oBrix or titratable acidity was observed. Model predictions developed for Hunter colour values, cloud value, non-enzymatic browning and ascorbic acid content were closely correlated (R ² > 0.92) to experimental data. Box–Behnken design and RSM was demonstrated to be an effective technique to model the effect of sonication on juice quality while minimising the number of experiments required.     

Spectrophotometric Determination of Trace Nitrite with Brilliant Cresyl Blue Using β-Cyclodextrin as a Sensitizer

A simple and sensitive spectrophotometric method for determination of nitrite has been described. The method is based on the oxidation of brilliant cresyl blue (BCB) by nitrite in acidic medium, which results in the decrease in absorbance at 636 nm. The decrease in absorbance is directly proportional to nitrite concentration obeying Beer’s law. The sensitivity is largely enhanced in the presence of β-cyclodextrin (β-CD) because of inclusion complexation. It was calculated that β-CD and BCB could form 1:1 inclusion complexation with a formation constant of 546.6 L/mol. Linear calibration graphs were obtained for 0.02 × 10⁻³–0.8 × 10⁻³ g/L sodium nitrite at 636 nm. The detection limit for the analytical procedure was 4.0 × 10⁻⁶ g/L sodium nitrite. The relative standard deviation for determination of 0.1 × 10⁻³ g/L and 0.5 × 10⁻³ g/L sodium nitrite were 0.69% and 0.38%, for ten determinations, respectively. Twenty-two coexistent ions or species were examined, and no serious interference for most of ions was observed. The method has been applied to determine nitrite in water and vegetable samples with satisfactory results.     

Characterization of Main Anthocyanins Extracted from Pericarp Blue Corn by MALDI-ToF MS

The anthocyanic composition of pigmented Mexican corn (Zea mays) has been investigated. Two extracts (hydrolyzed and non-hydrolyzed) were analyzed by HPLC at different temperatures. The separation profile obtained in chromatography was different for minor components but the main fraction was the same in both cases. The last anthocyanin fraction was collected and analyzed by MALDI-ToF MS. The compounds identified in the fraction were cyanidin-3-glucoside and pelargonidin-3-glucoside with an approximate content of 1 × 10⁻⁶ and 1 × 10⁻⁷ M for the hydrolyzed and non-hydrolyzed, respectively.     

Thin Layer Drying of African Breadfruit (Treculia africana) Seeds: Modeling and Rehydration Capacity

African breadfruit (ABF) seeds are underutilized plant resources, which have been reported to have high potential for novel food and industrial uses. The kinetics of moisture removal during air drying of the whole (WS) and dehulled (DS) seeds was studied at temperatures of 40–70 °C. Five empirical models were tested for predicting the experimental data. Drying of ABF seeds followed an exponential decay pattern, while drying predominantly took place during the falling rate periods. All the drying models predicted the experimental data above 90% accuracy while the Henderson–Pabis model gave the best fit (0.95 < r ² < 0.99) at most of the experimental conditions. Effective moisture diffusivity, D _eff, ranged from 3.65 to 7.15 × 10⁻⁹ m²/s and 3.95 to 6.10 × 10⁻⁹ m²/s for WS and DS, respectively. D _eff showed significant dependence on the moisture content (p < 0.01). Rehydration capacity of DS was not significantly affected by drying temperature while that of WS increased with drying temperature.     

Study of the diffusion coefficients of diphenylbutadiene and triclosan into and within meat

The migration of two chemicals, diphenylbutadiene and triclosan, was the target of this paper. Pork meat with different fat contents was prepared to study the influence of this parameter in the migration levels and to study the rate of diffusion of these migrants into the whole plastic/foodstuffs system and within the foodstuff. The whole system plastic/foodstuff diffusion coefficient (effective D) was calculated according to an equation based on the Fick’s Second Law, and D within the foodstuff (D _F) was calculated according to the Moisan equation. At 5 °C, D _F was 1.6 × 10⁻⁷ and 1.7 × 10⁻⁷ cm²/s for DPBD and triclosan, respectively. At 25 °C, D _F was 3.7 × 10⁻⁷ and 3.9 × 10⁻⁷ cm²/s for DPBD and triclosan, respectively. As expected, D within the pork meat is faster than the whole system D, which means that the interface plastic/foodstuff may be the limiting step for the mass transport of chemicals from the packaging to the foodstuff.     

Determination of Histamine in Some Foods by Isotachophoretic Method with Simple Sample Preparation

A one-dimensional capillary isotachophoretic method in cationic system of the separation has been applied for histamine determination in food samples. The proposed electrolyte system consisted of 0.01 M potassium hydroxide with l-valine to pH = 9.9 as the leading electrolyte and 0.02 M 2-amino-2-hydroxymethyl-propane-1,3-diol adjusted to pH = 8.3 with 0.1 M hydrochloric acid as terminating electrolyte. Proposed method was characterized by linearity range 5–50 mg L⁻¹ and R ² = 0.9982, accuracy (recoveries ranged from 95% to 102%), detection (2.10 mg L⁻¹), and quantification (7.01 mg L⁻¹) limits. The sample preparation for proposed electrophoretic method included only simple extraction with trichloroacetic acid with filtration and derivatisation stage are avoided. The histamine concentration was determined in meat (turkey, chicken, beef and pork) and meat products (ripened sausage and dry-cured ham), fish (smoked salmon and mackerel), and different kind of mildew and mold ripened cheeses samples. The histamine content ranged from not detected level for fresh meat to 29.63 mg 100 g⁻¹ for cheese samples. The reversed phase HPLC was applied as reference method and the F-Snedecor test and the t test were employed to compare the precision and accuracy of the both methods. Positive correlations were found between the two analytical methods for histamine determination in food products. The obtained results indicate that the proposed electrophoretic method is simple, precise, accurate, and convenient.     

Enzymatic Catalytic Spectrophotometric Determination of Thiamine in Food

A highly sensitive and simple spectrophotometric method for the determination of thiamine based on inhibitory effect of thiamine on the hemoglobin-catalyzed reaction of H₂O₂ with acid chrome blue K was developed. The concentration of thiamine is linear with the percentage inhibition of system under the optimal experimental conditions. The calibration curve is linear in the range 3 × 10⁻⁷ to 3.00 × 10⁻⁵ M with the detection limit of 1.2 × 10⁻⁸ M. This method can be used for the determination of thiamine in food with satisfactory results.     

Electrochemical Determination of Phenothrin in Agricultural Formulations, Vegetables, and Storage Bags of Wheat and Rice by Differential Pulse Adsorptive Stripping Voltammetry (DP-AdSV)

An electroanalytical method has been developed for the determination of the pesticide phenothrin by differential pulse adsorptive stripping voltammetry on a hanging mercury drop electrode in universal buffer as supporting electrolyte. The best adsorption conditions were found to be pH 6.0, an accumulation potential of −0.6 V, and an accumulation time of 75 s. Effects of stirring rate, scan rate, pulse amplitude, and purge time were examined for the optimization of instrumental conditions. Calibration curve is linear in the range 2 × 10⁻⁹ to 2 × 10⁻⁷ mol l⁻¹ with a detection limit of 1.9 × 10⁻¹⁰ mol l⁻¹. The correlation coefficient and relative standard deviation were 0.995% and 1.1%. The method is applied to the determination of the phenothrin in agricultural formulations, vegetables, and storage bags of wheat and rice under Food Corporation of India’s storage system.     

Extraction of Bioactive Compounds from Milled Grape Canes (Vitis vinifera) Using a Pressurized Low-Polarity Water Extractor

Trans-resveratrol and trans-ε-viniferin were extracted from milled grape canes using pressurized low-polarity water. The effects of temperature were significant for both compounds (p ≤ 0.05): extraction at 160 °C resulted in a 40% loss of trans-resveratrol compared to 95 °C while reduction of trans-ε-viniferin at both temperatures remained at 30%. Increasing ethanol concentration from 0% to 25% increased the extraction of total phenolics and trans-ε-viniferin by 44% and 489%, respectively. Solvent flow rate also influenced trans-ε-viniferin extraction. Antioxidant activity showed a strong correlation with total phenolic content of the extracts, and the two target phenolic compounds. Except for the modifier concentration, the extraction parameters studied were not statistically significant with respect to the antioxidant activity of extracts (p > 0.05). Effective diffusivities of trans-resveratrol multiplied from 3.3 × 10⁻¹¹ to 10.4 × 10⁻¹¹ m²/s by three times with increasing temperature. The modified Gompertz equation satisfactorily explained the extraction of the stilbenes investigated.     

A Sensitive, Selective New Analytical Reagent, 2, 6-Diacetylpyridine bis-4-phenyl-3-thiosemicarbazone for Extractive Spectrophotometric Determination of Mo(VI) in Food Samples

Synthesized a new reagent 2, 6-Diacetylpyridine bis-4-phenyl-3-thiosemicarbazone (2, 6-DAPBPTSC) characterized and is proposed as a sensitive and selective analytical reagent for the extractive spectrophotometric determination of molybdenum(VI) at pH 3.5 to form a yellowish orange colored 1:1 chelate complex. The absorbance was measured at a maximum wavelength, 500 nm. This method obeys Beer’s law in the concentration range 0.90–9.00 μg mL⁻¹ and the correlation coefficient of Mo(VI)–2,6-DAPBPTSC complex is 0.954, which indicates an adequate linearity between the two variables with good molar absorptivity and Sandell’s sensitivity, 1.212 × 10⁴ L mol⁻¹cm⁻¹, 0.0079 μg cm⁻², respectively. The precision and accuracy of the method is checked with calculation of relative standard deviation (n = 5), 0.894% and the detection limit value is 0.0056 μg mL⁻¹. The instability constant of the method has been calculated by Asmus’ method as 6.476 × 10^–5, at room temperature. The interfering effect of various cations and anions has also been studied. The method was successfully applied for the determination of Mo(VI) in food and water samples. The validity of the present method was evaluated in terms of Student ‘t’ test and Variance ‘f’ test, which indicates the significance of the present method an inter comparison of the experimental values, using atomic absorption spectrometer.