Camel milk protein hydrolysates with improved technofunctional properties and enhanced antioxidant potential in in vitro and in food model systems

Camel milk protein hydrolysates (CMPH) were generated using proteolytic enzymes, such as alcalase, bromelain, and papain, to explore the effect on the technofunctional properties and antioxidant potential under in vitro and in real food model systems. Characterization of the CMPH via degree of hydrolysis, sodium dodecyl sulfate-PAGE, and HPLC revealed that different proteins in camel milk underwent degradation at different degrees after enzymatic hydrolysis using 3 different enzymes for 2, 4, and 6 h, with papain displaying the highest degradation. Technofunctional properties, such as emulsifying activity index, surface hydrophobicity, and protein solubility, were higher in CMPH than unhydrolyzed camel milk proteins. However, the water and fat absorption capacity were lower in CMPH compared with unhydrolyzed camel milk proteins. Antioxidant properties as assessed by 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activities and metal-chelating activity were enhanced after hydrolysis, in contrast to ferric-reducing antioxidant power which showed a decrease after hydrolysis. The CMPH were also tested in real food model systems for their potential to inhibit lipid peroxidation in fish mince and grape seed oil-in-water emulsion, and we found that papain-produced hydrolysate displayed higher inhibition than alcalase- and bromelain-produced hydrolysates. Therefore, the CMPH demonstrated effective antioxidant potential in vitro as well as in real food systems and showed enhanced functional properties, which guarantees their potential applications in functional foods. The present study is one of few reports available on CMPH being explored in vitro as well as in real food model systems.     

Rosemary (<Emphasis Type="Italic">Rosmarinus officinalis</Emphasis>) oil: composition and functionality of the cold-pressed extract

The aim of this work was to investigate cold-pressed rosemary oil (RO) for its lipid classes, subclasses, fatty acid composition, tocochromanols and total phenolics amount. Antiradical activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH^?) and galvinoxyl radicals, antioxidant activity, as measured by the Rancimat test, as well as antimicrobial activity against food-borne bacteria, and dermatophytic fungi of RO were evaluated. In RO, the amount of neutral lipids was highest (ca. 86%), followed by phospholipids (0.92%) and glycolipids (0.88%). The percentages of monounsaturated, polyunsaturated, and saturated fatty acids were 41.7, 42.3, and 15.8%, respectively. Linoleic acid (41.7%) and oleic acid (41.2%) were the major fatty acids while linolenic acid accounted for 1.3% of total fatty acids. The following tocochromanols were detected: α-, β-, γ- and δ-tocopherols, which accounted for 291, 22, 1145, and 41 mg/100 g oil, respectively, as well as α-, β-, γ- and δ-tocotrienols, which accounted for 18, 12, 29, and 158 mg/100 g oil, respectively. RO also contained high levels of phenolic compounds (7.2 mg GAE/g). After 60 min of reaction with free radicals, 67% of DPPH^? and 55% of galvinoxyl radicals were quenched by RO. Rancimat test showed that blending RO with sunflower oil increased the induction period (IP) for blends. The IP of the RO: sunflower oil blend (1:9, v/v) was 390 min, and RO: sunflower oil blend (2:8, v/v) was longer (540 min). RO exhibited high antimicrobial potential against food-borne pathogenic bacteria (E. coli, S. enteritidis, and L. monocytogenes) and high antifungal potential against dermatophyte fungi (T. mentagrophytes, and T. rubrum). RO had unique high level of γ-tocopherol, which is a scavenger of reactive nitrogen species making it a promising material in the food, cosmetic and pharmaceutical applications.     

Studying the Effect of Household-Type Treatment and Processing on the Residues of Ethion and Profenofos Pesticides and on the Contents of Capsaicinoids in Green Chili Pepper Using GC-MS/MS and HPLC

The first aim of this study was to create, test, and apply a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, based on acetonitrile extraction, for simultaneous determination of pesticide residues in green chili pepper (fresh and dried forms). There is a group of 86 repeatedly detected pesticides in the agricultural food commodity in Al-Qassim region, Saudi Arabia. The suggested method is utilizing GC-MS/MS for simultaneous determination of those 86 pesticides. The limit of quantitation (LOQ) for each pesticide was set as the lowest fortification level that achieved acceptable recoveries in the range 70–120% with precision (RSD ≤ 20%). The results indicated that two organophosphorus pesticides, ethion and profenofos, in the analyzed chili pepper samples have significantly exceeded the European maximum residual limit (MRL) for pesticides. The second purpose of the study was to evaluate the effect of some different household-type treatment and processing procedures on the detected pesticide residues and on capsaicinoids (particularly, capsaicin and dihydrocapsaicin) which are responsible for the pungency of chili pepper, using GC-MS/MS and HPLC. Some recommendations were concluded for the best practices.     

Thermal diffusion and diffusion thermo effects of Eyring‐Powell nanofluid flow with gyrotactic microorganisms through the boundary layer

In this article, the effects of thermal diffusion and diffusion thermo on the motion of a non‐Newtonian Eyring Powell nanofluid with gyrotactic microorganisms in the boundary layer are investigated. The system is stressed with a uniform external magnetic field. The problem is modulated mathematically by a system of a nonlinear partial differential equation, which governs the equations of motion, temperature, the concentration of solute, nanoparticles, and microorganisms. This system is converted to nonlinear ordinary differential equations by using suitable similarity transformations with the appropriate boundary conditions. These equations are solved numerically by using the Rung‐Kutta‐Merson method with a shooting technique. The velocity, temperature, concentration of solute, nanoparticles, and microorganisms are obtained as functions of the physical parameters of the problem. The effects of these parameters on these solutions are discussed numerically and illustrated graphically through figures. It is found that the velocity decreases with the increase in the non‐Newtonian parameter and the magnetic field, whereas, the velocity increases with a rise in thermophoresis and Brownian motion. Also, the temperature increases with an increase in the non‐Newtonian parameter, magnetic field, thermophoresis, and Brownian motion. These parameters play an important role and help in understanding the mechanics of complicated physiological flows.     

Inorganic thermoelectric materials: A review

Thermoelectric generator, which converts heat into electrical energy, has great potential to power portable devices. Nevertheless, the efficiency of a thermoelectric generator suffers due to inefficient thermoelectric material performance. In the last two decades, the performance of inorganic thermoelectric materials has been significantly advanced through rigorous efforts and novel techniques. In this review, major issues and recent advancements that are associated with the efficiency of inorganic thermoelectric materials are encapsulated. In addition, miscellaneous optimization strategies, such as band engineering, energy filtering, modulation doping, and low dimensional materials to improve the performance of inorganic thermoelectric materials are reported. The methodological reviews and analyses showed that all these techniques have significantly enhanced the Seebeck coefficient, electrical conductivity, and reduced the thermal conductivity, consequently, improved ZT value to 2.42, 2.6, and 1.85 for near-room, medium, and high temperature inorganic thermoelectric material, respectively. Moreover, this review also focuses on the performance of silicon nanowires and their common fabrication techniques, which have the potential for thermoelectric power generation. Finally, the key outcomes along with future directions from this review are discussed at the end of this article.     

Investigations on tyrosinase activity in melanin-free ink from Sepia officinalis: potential for food proteins cross-linking

Protein modification via enzymatic cross-linking is an attractive way for altering food structure so as to create products with increased quality and nutritional value. In this study, enzymatic cross-linking of β-casein was performed by tyrosinase activity, from melanin-free ink from Sepia officinalis, which was monitored by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) techniques. The melanin-free ink contains a strong tyrosinase activity with pH 7 and 58?°C as optima of pH and temperature, respectively. Such activity is stimulated by ferrous ions and strongly inhibited by Mn²⁺, EDTA, H₂O₂, arbutin, and p-coumaric acid. We also show that 2 Mercapto-ethanol (14?mM) quickly and completely inactivated sepia tyrosinase. The melanin-free ink exhibits a major protein on SDS–PAGE with an N-terminal sequence matching perfectly with an internal sequence of the sepia peroxidase. The zymogram confirmed the inactive state of this truncated protein and the presence of an active tyrosinase enzyme. Interestingly, this activity was able to cross-link the β-casein protein. The tyrosinase implication in reticulation was demonstrated by the addition of its inhibitors, with 2-mercaptoethanol being the most effective, followed by arbutin, p-coumaric acid, and hydrogen peroxide.     

Inhibition of enterotoxicogenic strains Bacillus cereus GT1 and Staphylococcus aureus S1 isolated from double white cream cheese

In this study three different food preservatives (sodium nitrate, sodium benzoate and sodium sorbate) were used to evaluate their effect on two enterotoxicogenic strains (Bacillus cereus GT1 and Staphylococcus aureus S1). A significant decrease in the viability and production of virulence factors was observed. Yet, obvious tolerance to increasing concentrations (from 1 to 6?g/l) of the three preservatives was recorded reflecting possible resistance mechanisms within the tested strains. The two strains were subjected to increasing doses of gamma radiation (1, 2, 3, 4, 5, 6, 7, 8, 9 and 10?kGy). Obvious correlation was observed between the initial counts of bacterial spores contaminating the products and the required dose for their complete elimination. Whereas the eliminating dose of B. cereus GT1 strain was 10?kGy only 4?kGy was sufficient to suppress the growth and virulence of S. aureus S1, reflecting its sensitivity to low doses of gamma irradiation. Also, inhibition of the two strains by probiotic strain Bacillus pumilus G4 was studied both in situ (in cheese) and in vitro (in culture media). The viable cell population of B. cereus GT1 increased from 10⁶ to 2.9?×?10⁸?CFU/g within 60?h in controls but decreased from 2.1?×?10⁶ to 2.3?×?10³?CFU/g after treatment with the probiotic strain. No viable count was observed after 60?h of incubation. Whereas, the viable cell population of S. aureus S1 increased from 10⁶ to 2.5?×?10⁸?CFU/g within 60?h in controls but decreased from 1.5?×?10⁶ to 4.3?×?10²?CFU/g after treatment with the probiotic strain. No viable count was observed after 54?h of incubation.     

Enhancement of Red Pigment Production by Monascus purpureus FTC 5391 through Retrofitting of Helical Ribbon Impeller in Stirred-Tank Fermenter

The possibility of using a novel proximity type half-pitched, double-flight helical ribbon impeller (HRI) for the improvement of red pigment production by Monascus purpureus FTC5391 was investigated in a 2-L stirred-tank fermenter (STF). For comparison, the fermentations were also carried out in STF equipped with the industrial standard six-bladed Rushton turbines (RT). The selection of aeration and agitation strategies in STF were based on possible attainable oxygen transfer at the start of fermentation using derived empirical power law model to predict the initial volumetric oxygen transfer coefficient (k _L a). The final pigment concentration, yield, and productivity obtained in optimized fermentation employing a single HRI agitated at 250 rpm and air flow rate of 2.25 L/min (1.5 vvm) was 24.36 UA₅₀₀, 0.47 UA₅₀₀/g glucose, and 0.20 UA₅₀₀/h, respectively. These values were about 76%, 78%, and 96% higher than those obtained in STF fitted with RT, respectively. In terms of impeller power consumption, the HRI system was favorable for batch cultivation of M. purpureus as pigment yield per energy invested was 2.5 times higher than the RT.