Food Biotechnology
Zhila Ghasemi; Mohammad Alizadeh khaled abad; Hadi Almasi; Mehdi Nikoo
Abstract
Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization ...
Read More
Nowadays, probiotics have been seriously considered for their potential application in healthy food formulations. The most highlighted concern about probiotics is that the number of probiotic bacteria at the time of consumption may be lower than the required value (107 CFU/g). A new approach is the immobilization of probiotic cells in the matrix of edible films. So in this study, edible carboxymethyl cellulose (CMC) probiotic films containing Lactobacillus casei, and the silver carp muscle protein hydrolysates (SCMH) prepared by using limited Alcalase hydrolysis, were analyzed and the viability of bacterial cells was determined at 25, 4, and -18°C for 30 days. An alkaline solubilization/acid precipitation method was used to isolate silver carp white muscle proteins. Protein isolate (3%, W/V) was hydrolyzed with 5% E/S ratio (w/w) Alcalase at 50°C and pH 8.0 for 3 min. Briefly, films were prepared by dissolving SCMH and CMC powder (1.5%, w/v) in a ratio of 1:2 in distilled water and L. casei was added to a final concentration of 108 CFU/mL. Probiotics were counted at intervals of 1, 10, 20, and 30 day. The physical, mechanical [Ultimate tensile strength (UTS) and elongation at break (EB)], thermal and structural properties were determined. XRD patterns of the film samples collected by X-ray diffractometer (XRD) and Fourier transform infrared (FT-IR) spectroscopy of the film samples were recorded. The results indicated that the addition of SCMH significantly (p˂0.05) improved the L. casei viability at all three temperatures. Thickness, moisture absorption, and water vapor permeability (WVP) of the films were not influenced by addition of the probiotic. However, the addition of SCMH negatively affected the film’s mechanical properties. The FT-IR analysis confirmed the formation of hydrogen bonds between L. casei and the CMC matrix, the XRD and differential scanning calorimetry (DSC) analyses confirmed the plasticizing effect of SCMH on the films. Thus, CMC films containing L. casei showed the highest UTS (3.7 MPa) and EB (29.9%). Generally, the results indicated that the SCMH incorporated CMC-based film can be a good carrier for probiotics as bioactive food packaging system with promising potential for shelf life extension of perishable foods.
Nasrin Faraji; Mohammad Alizadeh khaled abad; Hadi Almasi; Sajad Pirsa; Soheila Faraji
Abstract
Introduction: Fish oil is an omega3 source, because it consists of a long chain polyunsaturated fatty acids (PUFAs), namely Eicosapentaenoic acid (EPA, 20:5 n-3) and Docosahexaenoic acid (DHA, 22:6 n-3) that are essential to all humans and provide multiple health benefits associated with brain development, ...
Read More
Introduction: Fish oil is an omega3 source, because it consists of a long chain polyunsaturated fatty acids (PUFAs), namely Eicosapentaenoic acid (EPA, 20:5 n-3) and Docosahexaenoic acid (DHA, 22:6 n-3) that are essential to all humans and provide multiple health benefits associated with brain development, cardiovascular disease, circulatory disorders, immune dysfunction and inflammatory disorders. The human body cannot make omega3 fatty acids on its own, so they must obtained from daily diet or supplements. Low uptake of this nutrient can cause serious problems. Lipid oxidation of fish oil and other PUFA-rich foods is a serious problem that leads to loss of shelf-life, consumer acceptability, nutritional value and functionality. On the other hands, omega3 cannot be incorporated into many functional foods, due to their poor water-solubility, chemical instability and low bioavailability, so some ways should be used to protect PUFAs such as microencapsulation and Nanoemulsion. The performance of low-energy methods has become very popular due to the lack of expensive equipments and ease of production. In this research, nanoemulsion of omega-3 fatty acids was prepared by spontaneous emulsification method using Iranian mentha longifolia essential oils. Material and methods: Fish oil was purchased from zahravi company comprised of 101 mg of EPA/g of oil, 148 mg of DHA/g oil, and 312 mg of total omega-3 PUFA/g of oil. Nonionic surfactants Tween 80 and Tween20 (Sigma Aldrich, St. Louis, MO, USA) and Sodium caseinate (MP Biomedical LLC. (Solon, OH) were purchased from chemical suppliers. Distilled and deionized water obtained from a water purification system (Milli-Q, Millipore, Darmstadt, Germany) was used to prepare all emulsions. All other chemicals used in this study were either Sigma-Aldrich (St. Louis, MO) or Fisher Scientific (Pittsburgh, PA). Iranian Shallot oil (penny royal oil) was purchased from magnolia company (Iran). The supplier reported the chemical composition as determined by gas chromatography-mass spectroscopy instrument (GCMS-QP2010 SE, GAS, Shimadzu, Japan). Factor A contains the omega 3 percent (25 to 75 percent), factor B contains surfactant-to-oil ratio (SOR %), (10-300 percent), Factor c contains surfactant type (Tween20, Tween80, T80:T20 and caseinate sodium) and factor d contains storage time (1-60 days) to achieve optimal production formula were selected. Physicochemical characteristics of Nanoemulsion including pH, peroxide value, turbidity, creaming index, D43, span, antioxidant, brix, refractive index and TBA were studied and Optimization of formula was performed by Response Surface Method (D-optimal design) The results were analyzed using design expert software (ver11). Results and discussion: Preparation of Nanoemulsion based on Iranian mentha longifolia oil loaded with omega 3 fatty acids by a low energy emulsification technique to protect it was evaluated in this study. The initial size of the droplets depended on surfactant type, surfactant concentration, storage time and omega3 concentration. Emulsions made of the highest surfactant concentration produced the smallest droplet sizes and were physically stable. It was found that the most important parameter effecting final emulsion responses was surfactant concentration. Our results showed that oxidative stability could be improved by the increasing surfactant concentration, also Iranian mentha longifolia antioxidant compounds were effective in reducing peroxide index and delaying oxidation. In all surfactants, by increase omega3 content, antioxidant activity was decreased. Results showed that all four examined variables affected the provided emulsion characteristics and the following conditions were obtained as optimum; storage time of 40 days, SOR %: 100, T80:T20 and omega 3 (29.31%). These nanoemulsions and essential oils can be applied to prevent undesirable off flavor fish oil and can be applied to fortify food or beverage systems with omega3 fatty acids.
Eisa Jahed; Hadi Almasi; Mohammad Alizadeh khaled abad
Abstract
Introduction: Due to increasing attention to the environment, as well as consumer demand for healthy, nutritive food products and extended shelf life, in the recent years, the food and packaging industries have paid increasing attention to biodegradable edible packaging prepared from biopolymers such ...
Read More
Introduction: Due to increasing attention to the environment, as well as consumer demand for healthy, nutritive food products and extended shelf life, in the recent years, the food and packaging industries have paid increasing attention to biodegradable edible packaging prepared from biopolymers such as proteins, polysaccharides, and lipids or their combinations. These biodegradable films may act as carrier of wide variety of additives, such as antimicrobial, antioxidant agents, flavors, colorants and spices which improve the functionality of the packaging materials by addition of novel or extra functions. In the present study, an antioxidant/antimicrobial active packaging based on chitosan biopolymer was designed. For this purpose, lignocellulose nanofibers (LCNF) and cellulose nanofibers (CNF) at concentration of 4% were used as reinforcement of biopolymer properties, as well as to control the release of Origanum vulgare subsp. gracile and Carum copticum essential oils (as antioxidant/antimicrobial agent) from the packaging material into the foodstuff.
Materials and methods: The O. vulgare ssp. gracile leaves and C. copticum seeds were obtained from wild plants in mountains of Urmia (Iran). LCNF (average diameter about 55 nm, average length about 2–5 μm, 99% purity) produced from unbleached hardwood pulp through mechanical and acid treatments and CNF (average diameter about 28 nm, average length about 2–3 μm, 99% purity) prepared from softwoods through mechanical disintegration were kindly provided by Nano Novin Polymer Co. (Saari, Iran). Chitosan (medium molecular weight, from shrimp shell with a deacetylation degree of 75–85%), purchased from Sigma-Aldrich (St. Louis, MO, USA). Chitosan based bionanocomposite films incorporated with organic nanofillers and essential oils were developed by solvent casting method. The synthesized films were characterized by XRD and DSC analyses. To determine the prepared films would have potential to be used as an active packaging, water vapor permeability, water solubility, color, transparency, mechanical properties, antimicrobial and antioxidant activity of the films were also evaluated. In order to determine the efficiency of activated nanocomposites, the effect of these films was evaluated on the oxidative stability of rapeseed oil without antioxidants and compared with the effect of TBHQ synthetic antioxidant.
Results & Discussion: The results showed that the addition of essential oils did not have a significant effect on the crystallinity and thermal properties of the films, while organic reinforcement increased the crystalline properties and thermal resistance of nanocomposite films. By applying the essential oils and CNF and LCNF in the structure of the films, the apparent transparency and consequently the amount of light passage from them decreased compared to the control sample. With addition of essential oils separately and in combination, as well as CNF and LCNF in the structure of films, solubility and film permeability decreased compared to pure chitosan film. By adding of two essential oils with a ratio of 50:50, tensile strength (UTS) and strain to break (STB) of films were increased, while organic nanofibers led to an increase in UTS and a significant reduction in STB of nanocomposites. It was also found that active films containing different ratios of essential oil had remarkable antioxidant activity and high antimicrobial activity against E.coli and B.cereus bacteria, which by adding CNF and LCNF these features were reduced due to the role of controlling the release of essential oil compounds by nanofibers. With the numerical optimization of the software, the optimal amount for the essential oils of C. copticum and O. vulgare oils were 2.29 and 2.71% (5% mix) respectively, in combination with the LCNF nanofibers. The results of oxidative stability of Canola oil showed that nanocomposites containing 5% essential oil were considerably able to keep the oil freshness during storage at ambient temperature and delay the oxidation of the oil.
Nazila Dardmeh; Asghar Khosrowshahi; Hadi Almasi; Mohsen Zandi
Abstract
Introduction: Nanocomposites are prepared by introduction of dispersed nanoscale particles into the polymer matrix based on four methods: template synthesis (sol-gel preparation); intercalation of polymer; and in situ intercalative polymerization and last one is melt blending, the most favorable and ...
Read More
Introduction: Nanocomposites are prepared by introduction of dispersed nanoscale particles into the polymer matrix based on four methods: template synthesis (sol-gel preparation); intercalation of polymer; and in situ intercalative polymerization and last one is melt blending, the most favorable and practical method due to its simplest, economical and environmentally friendly technic. This method involves annealing, statically or under shear, a mixture of the polymer and organically modified clay at the softening point of the polymer based on usual compounding devices, such as, extruders or mixers (Papaspyridesb 2008). PET is a semicrystalline thermoplastic polyester which has been extensively used in all sizes as a packaging material in direct contact with food, beverages and as an alternative packaging to polyvinyl chloride for edible oils (Kirwan et al. 2011). As polymeric nanocomposites are mainly used as structural materials, the layered silicate clay are preferred. The crystal lattice of 2:1 layered silicates, consists of two-dimensional layers where a central octahedral sheet of alumina is fused to two external silica tetrahedral by the tip. Montmorillonite (MMT) belongs to type 2:1 layered smectite clay which in the basic structure, the trivalent Al-cation in the octahedral layer is partially substituted by the divalent Mg-cation (Pavlidoua and Papaspyridesb 2008). As evident, MMT is greatly hydrophilic in the interlayer and incompatible with organic polymer such as PET, thus to increase compatibility of clay with polymer, inorganic inter-layer cations (Na+, K+ or Ca2+) exchanged by the cationic surfactants (e.g., quaternary ammonium salt). Modified MMT or organoclay interacts better with polymer due to its increased gallery space (Utracki et al. 2007; Parvinzadeh et al.2010). Three different types polymer/clay nanocomposites can be obtained depending on the preparation method and the nature of the components used, including polymer matrix, layered silicate and organic cation. Tactoid nanocomposites formed when stacks of modified layered silicates are retained after introduction into the polymer. Subsequently, interaction between the nanolayers and polymer is not only unsuccessful but reduces mechanical properties of composite as well. Our main objective of this research was to study the effect of the nanoclay addition on mechanical, colorimetric and transparency properties of poly (ethylene terephthalate) (PET) nanocmposite films. Materials and methods: Bottle-grade poly (ethylene terephthalate) granules with intrinsic viscosity of (IV) = 0.82 dl g-1 were provided by the Iranian Tondgooyan Petrochemical company. The organically modified montmorillonite, Cloisite 15A, was supplied by Southern Clay Products Inc. Standard of TPA was supplied from Fluka Chemical, trademarked Sigma-Aldrich Corp., Switzerland. High-pressure liquid chromatography (HPLC) grade water, aceto-nitrile, acetic acid and methanol (HPLC grade) were purchased from Merck (Darmstadt, Germany). TPA was dissolved into methanol with a slight increase in temperature. Working standard solutions were prepared on the day of use at concentrations of 0.4, 40, 100 and 1,000 ppb and calibration graphs were plotted using these concentrations of standard solutions. The PET granules and nanoclay particles were dried in an oven for 24 h at 110 and 80C before extrusion, respectively. Melt blending technique was used for preparing nanocomposite films in a co-rotating twin screw extruder ZSK 25 .The temperature profile (throat to die) was as follows: 250, 270, 275, 270, 270 and 265C with a screw speed of 250 rpm. PET granules were dry mixed with 1, 3, and 5% wt of Cloisite 15A. The total weight of material per batch was 300 g. The resulting nano-composite strand was cooled in a water bath, granulated and dried overnight in oven at 110C. A laboratory press with a temperature plates of 280C under a pressure of 5 MPa for 10 min was applied to compress specimens. Then cooled them in water and ice bath to achieve transparent films. The influence of different amount of nanoclay addition on resultant nanocmposites was studied by Fourier transform infrared spectroscopy (FT-IR) and mechanical test. Also, influence of nanoclay presence on water vapor permeability (WVP), color and transparency of the nanocomposites were investigated. Results & Discussion: The results showed that nanoclay addition improved the mechanical properties (Young’s modulus, elongation at break and tensile strength) and WVP up to 3% (wt). However, nanoclay addition reduced the transparency of resultant nanocomposites films but it prevented wave transmission at three UV region which leads to better protective effect of film as a food packaging materials. It seems that introduction of Cloisite 15A into the PET matrix reinforced the mechanical properties of resultant nanocomposites. The Young’s modulus of the nanocompo-sites significantly increased compared with the neat PET, indicating that PET/Cloisite 15A nanocomposites were stiffer than PET. The maximum Young’s modulus was observed for PET/C15A containing 3% wt with an increment about 8 MPa. This increase in modulus may be attributed to uniform dispersion and alignment of nanoclay along with compatibil-ity with PET matrix as confirmed by XRD, DSC and SEM. The Young’s modulus enhancement is consistent with that of other research (KIMet al. 2007; Scaffaroet al. 2011; Ghanbari et al. 2013a,b]. Tensile strength like elongation at break shows same trend, increases on increasing nanoclay content except for nanocomposite containing 5% which indicates brittle behavior compared to PET. This can be explained consider-ing that higher aspect ratio of nanoclay tends to aggregate and forms tactoids (as shown in SEM and XRD) and conse-quently indicates poor mechanical properties.
Mohsen Zandi; Nazila Dardmeh; Sajad Pirsa; Hadi Almasi
Abstract
Ohmic heating has an advantage over conventional indirect heating methods because heater (electrode) surfaces temperatures are comparatively lower as heat is generated within bulk fluid. Conventional ohmic heating under typical low frequency alternating current (50 or 60 Hz) could cause hydrogen and ...
Read More
Ohmic heating has an advantage over conventional indirect heating methods because heater (electrode) surfaces temperatures are comparatively lower as heat is generated within bulk fluid. Conventional ohmic heating under typical low frequency alternating current (50 or 60 Hz) could cause hydrogen and oxygen evolution due to electrolysis of water. This process could develop the electrodes decay or corrosion. Any decay or corrosion of electrodes shorten the life time and contaminate the food.in this study Concentrations of Fe, Cr, Ni, Mn, and Mo from the stainless steel electrode migrated into ohmically and conventionally treated soup were measured. migration of the major key metal ions from stainless steel measured by Atomic Absorbtion shows that Overall ohmic treatment yielded reduced migration residues of all metal ions, compared to the conventional retorting with similar electrodes. Concentrations of all metal ions migrated into food samples after ohmic treatment were far lower than dietary exposure levels so that this technique can ensure the safety and quality of food supplies.
Hadi Almasi; Babak Ghanbarzadeh; Jalal Dehghan nia; Ali Akbar Entezami; Asghar Khosrowshahi Asl
Abstract
Fatty acid modified cellulose nanofibers (MCNFs) and TBHQ antioxidant were added to poly(lactic acid) (PLA) film. The combined effects of the MCNFs and TBHQ on the morphological, thermal, mechanical and barrier properties of PLA film were analyzed. The morphology of fracture surfaces evaluated by field ...
Read More
Fatty acid modified cellulose nanofibers (MCNFs) and TBHQ antioxidant were added to poly(lactic acid) (PLA) film. The combined effects of the MCNFs and TBHQ on the morphological, thermal, mechanical and barrier properties of PLA film were analyzed. The morphology of fracture surfaces evaluated by field emission scanning electron microscopy (FE-SEM). XRD results showed that the crystallinity of the PLA film with added MCNFs was substantially higher than that of pure PLA and antioxidant active PLA films. Glass transition and melting temperatures changed with the addition of these two components. The addition of 3wt% of TBHQ to PLA films leads to a significant reduction (p
