Banana starch modified by heat moisture treatment and annealing: Study on digestion kinetics and enzyme affinity.

Starch modification by annealing (ANN) and heat-moisture treatment (HMT) results in a lower crystallinity compared to native but the change of B crystalline type to A type is only observed in HMT starch. All starches possess two different digestion rate constants i.e. k1 (at rapid phase) and k2 (at slow phase) which may be linked to the preserved intact starch granule following thermal treatment. HMT starch contains higher content of slowly digestible starch (C2∞) compared to the C2∞ of the other starches. The lower enzyme binding to HMT starch (Kd value increases from 0.12 mg/mL in native starch to 0.83 mg/mL) may be linked to the increase in the degree of ordered structure of the granule surface (observed from the absorption band ratio of 1000 cm-1/1022 cm-1). The lower affinity may lead to a lower k1 value. This holds true for ANN and native starch which displays similar k1, Kd value and degree of ordered to disordered structure. Lower k2 in HMT starch compared to the corresponding k2 in the other starches may be linked to the slower enzyme diffusion into the core of starch granule due to the tightly packed structure of A crystalline type in HMT starch.

Effects of alkaline pH and gallic acid enrichment on the physicochemical properties of sesame protein and common vetch starch-based composite films.

In this study, sesame (Sesamum indicum L.) meal protein and common vetch (Vicia sativa L.) starch were extracted and used to obtain biodegradable composite films at different pH values (7, 9, and 11). Films were plasticized with glycerol (2.5 %) and enriched with gallic acid (0.25 %). Increasing pH promoted mechanical properties of the films with the developed barrier and thermal characteristics. Gallic acid addition at pH 7 resulted in lower tensile strength and higher elongation by reducing intermolecular forces, and a shift of diffraction peaks through lower angles due to crystal lattice expansion, as compared to neutral films without gallic acid. On the other hand, gallic acid-enriched films at neutral pH exhibited superior antioxidant properties. The mild alkalinity with gallic acid provided the lowest water vapor permeability, high thermal stability, improved mechanical properties and light barrier property due to deprotonation and subsequent interactions with biopolymers. The FTIR spectrum confirmed intense interactions, such as crosslinking and covalent bonding, promoted by mild alkalinity. Therefore, sesame protein and common vetch starch-based composite film with gallic acid incorporation at pH 9 can be recommended to be used in biodegradable active food packaging applications.

Effects of deacetylation degree of chitosan on the structure of aerogels.

Chitosan aerogels, obtained by (supercritical) CO2 drying of hydrogels, are novel adsorbents because of their large surface area and high porosity. Intrinsic properties of chitosan such as molecular weight (MW) and degree of deacetylation (DDA) had large impacts on the characteristics of chitosan aerogels. Although there are a few studies about the effects of solely DDA or MW on aerogel structure, none of them has focused on the mutual effects. The study aims to investigate the combined effects of MW and DDA of chitosan on aerogel properties. Hydrogels were produced in beads form by physical gelation of the chitosan solutions (2 % w/v in acetic acid of 1 %, v/v) in an alkaline environment (NaOH, 4 N). Supercritical CO2 dried aerogels were examined with respect to the bulk density, diameter as well as pore characteristics, and surface area by Barrett-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) methods, respectively. Morphologies of aerogels were also examined by Scanning Electron Microscopy (SEM) images and structural changes of aerogels were observed by Fourier Transform Infrared (FTIR) Spectroscopy. Additional to BET-BJH analysis, proton relaxation dispersion was measured by Fast Field Cycling NMR (FFC-NMR) to determine the pore volume of the aerogels. Compact structures were obtained for higher MW chitosan and lower MW chitosans with higher DDA increasing the aerogel diameters. All types of aerogels obtained by different chitosan characteristics (MW and DDA) showed a porous structure and the highest DDA with the lowest MW caused the minimum bulk density with the highest water absorption rate. Although different N2 adsorption-desorption profiles were obtained in terms of pore volumes; all aerogels had Type IV isotherms with Type H1 hysteresis curve. FFC-NMR experiments showed that the coherence length values were associated with the pore volumes and FFC-NMR experiments were found to be meaningful as supportive experiments for the characterization of aerogels.

The Effects of Citric Acid Crosslinking on Fabrication and Characterization of Gelatin/Curcumin-Based Electrospun Antioxidant Nanofibers.

Nanofibers, produced through the novel method of electrospinning, have a high ratio of surface area to volume, which allows them to have different optical, electrical, thermal, and mechanical properties than macroscale materials. In this study, it was aimed to produce nanofibers with gelatin and curcumin. The effects of gelatin concentration and crosslinking with citric acid on the characteristics of electrospun nanofibers were studied. Gelatin film containing neither citric acid nor curcumin was used as control. Solutions were evaluated by solution conductivity, color analysis, and rheological properties. Obtained nanofibers were characterized by morphological analysis (SEM), antioxidant activity (AA), thermal properties (TGA, XRD, DSC), water vapor permeability (WVP), and Fourier transform infrared (FTIR) analysis. It was found that the functional groups of gelatin were not changed significantly but some degree of crosslinking was seen, as indicated by the changes in AA, crystallinity, etc. Improvement in antioxidant activities was seen, which was the highest for gelatin and curcumin films (32%). The highest melting temperature (78 °C) and WVP (2.365 × 10-10 gm-1 s-1 Pa-1) was seen for gelatin and curcumin films crosslinked with 0.5% citric acid. Gelatin with curcumin films crosslinked with 1% citric acid showed the lowest crystallinity (1.56%). It was concluded that even though citric acid might not prove to be a stable crosslinking agent for the protein (gelatin), it contributed to the antioxidant nature of the films, along with curcumin. These films are promising candidates to be applied on cut fruits, to reduce water loss and oxidation and hence extend their shelf lives.

Development of curcumin incorporated composite films based on chitin and glucan complexes extracted from Agaricus bisporus for active packaging of chicken breast meat.

Composite films were prepared by combining different concentrations of curcumin with chitin and glucan complexes (CGCs) extracted from Agaricus bisporus via a solution casting method. The developed curcumin doped CGC (CGC/Cu) films were characterized in terms of surface, optical, structural, barrier, mechanical, antioxidant, and antimicrobial properties. The biodegradability of CGC/Cu films was determined in soil for 14 days. The incorporation of curcumin significantly affected the surface morphology and improved light barrier properties, radical scavenging activity, and total phenolic content of the films. The CGC/Cu films containing different concentrations of curcumin showed antibacterial activity against Escherichia coli, while antibacterial activity against Staphylococcus aureus was not observed with the developed films. Afterward, the microbial properties of the fresh chicken breast were examined during refrigerated storage for 10 days. The shelf-life of chicken samples wrapped in the developed film was extended at least 40 % compared to the control sample. In conclusion, curcumin incorporated CGC based films can serve as a promising biodegradable active packaging material to improve the shelf-life of meat products.

Encapsulation of Caffeic Acid in Carob Bean Flour and Whey Protein-Based Nanofibers via Electrospinning.

The purpose of this study was to introduce caffeic acid (CA) into electrospun nanofibers made of carob flour, whey protein concentrate (WPC), and polyethylene oxide (PEO). The effects of WPC concentration (1% and 3%) and CA additions (1% and 10%) on the characteristics of solutions and nanofibers were investigated. The viscosity and electrical conductivity of the solutions were examined to determine characteristics of solutions. Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), water vapor permeability (WVP), and Fourier transform infrared (FTIR) analysis were used to characterize the nanofibers. According to the SEM results, the inclusion of CA into nanofibers resulted in thinner nanofibers. All nanofibers exhibited uniform morphology. CA was efficiently loaded into nanofibers. When CA concentrations were 1% and 10%, loading efficiencies were 76.4% and 94%, respectively. Nanofibers containing 10% CA demonstrated 92.95% antioxidant activity. The results indicate that encapsulating CA into carob flour-WPC-based nanofibers via electrospinning is a suitable method for active packaging applications.

Correlation between physical and sensorial properties of gummy confections with different formulations during storage.

Gummy confections are popular products formulated with sucrose, glucose syrups, gelling agents, acids, flavourings and colouring agents. They have various commercial types in terms of formulation, texture, taste and colour, however, there is inadequate investigation on storage behavior of these products. The aim of this study is to investigate the effects of glucose syrup:sucrose ratio (1.1 and 1.5), starch (0% and 1.5%) and gelatine concentration (3% and 6%) on texture profile, colour and sensory properties of gummy confections during storage. It was also aimed to correlate sensorial changes with physical properties measured by instrumental techniques during storage at 10 °C, 20 °C and 30 °C. The highest increase in hardness was observed for formulation with 1.1 glucose syrup:sucrose ratio, no starch and 6% gelatine. Storage temperature had no significant effect on cohesiveness. It was seen that rate of colour change increased with storage time and temperature. Formulation with glucose syrup:sucrose ratio of 1.5, no starch and 6% gelatine had the highest sensory scores. This formulation was found to be the most stable formulation in terms of hardness and gumminess, meaning that it would need a stable mastication during storage. Sensorial changes of gummy confections were found to be correlated with instrumental results of texture and colour.

Monitoring freshness of chicken breast by using natural halochromic curcumin loaded chitosan/PEO nanofibers as an intelligent package.

Intelligent packaging is important to get information about real time quality of foods. The objective of this study was to develop an electrospun nanofiber halochromic pH sensor film using curcumin, chitosan (CS) and polyethylene oxide (PEO) to monitor chicken freshness. Conductivity and rheological behavior of CS/PEO/curcumin solutions were measured to understand the effect of solution properties on the morphology of the fibers. The morphological characteristics of nanofiber films were investigated by Field Emission Scanning Electron Microscopy (FESEM). Average diameter of the fibers was found to be between 283 ± 27 nm and 338 ± 35 nm. It was concluded that increasing CS amount in nanofibers decreased the diameter of the fibers. Thermal analysis and water vapor permeability features of the pH sensor were also examined. Color changes of curcumin loaded CS/PEO nanofiber film was evaluated on chicken breast package at 4 °C. The color of nanofiber film changed from bright yellow to reddish color which provided an opportunity to detect color changes by even the naked eyes of the untrained consumer. As a quality indicator, surface pH changes of the chicken breast and TVB-N (total volatile basic nitrogen) were measured. At the end of the day 5, pH value of 6.53 ±0.08 and TVB-N concentration of 23.45 ±3.35 mg/100 g indicated that food was at the edge of the acceptance level. As a result, curcumin loaded nanofiber satisfied the expectation and gave an opportunity to visualize real time monitoring of chicken spoilage.

Fabrication of gallic acid loaded Hydroxypropyl methylcellulose nanofibers by electrospinning technique as active packaging material.

The objective of this study was to encapsulate gallic acid in Hydroxypropyl methylcellulose (HPMC)/ polyethylene oxide (PEO) blend nanofiber by using electrospinning and examine the usage of nanofibers as active packaging materials. Gallic acid loaded nanofibers showed homogenous morphology. Gallic acid was loaded into nanofibers efficiently and nanofibers showed strong antioxidant activity. As the gallic acid amount increased, the TGA curves had shifted one stage to two stage degradation and degradation temperature (Td) of gallic acid decreased from 275 °C to 250 °C due to the crystalline structure change. Interaction between gallic acid and HPMC/PEO nanofiber demonstrated that gallic acid successfully embedded into the nanofibers. Gallic acid loaded nanofibers decreased the oxidation of walnut during storage. Overall, electrospinning technique was proved to be an efficient method to encapsulate bioactive compounds and gallic acid loaded nanofibers showed promissory results that can be suggested as great potential to active packaging material.

Effects of addition of different fibers on rheological characteristics of cake batter and quality of cakes.

The aim of this study was to investigate the effects of addition of dietary fibers on rheological properties of batter and cake quality. Wheat flour was replaced by 5 and 10% (wt%) oat, pea, apple and lemon fibers. All cake batters showed shear thinning behavior. Incorporation of fibers increased consistency index (k), storage modulus (G') and loss modulus (G″). As quality parameters, specific volume, hardness, weight loss, color and microstructure of cakes were investigated. Cakes containing oat and pea fibers (5%) had similar specific volume and texture with control cakes which contained no fiber. As fiber concentration increased, specific volume decreased but hardness increased. No significant difference was found between weight loss of control cake and cakes with oat, pea and apple fibers. Lemon fiber enriched cakes had the lowest specific volume, weight loss and color difference. When microstructural images were examined, it was seen that control cake had more porous structure than fiber enriched cakes. In addition, lemon and apple fiber containing cakes had less porous crumb structure as compared to oat and pea containing ones. Oat and pea fiber (5%) enriched cakes had similar physical properties (volume, texture and color) with control cakes.

A novel electrospun hydroxypropyl methylcellulose/polyethylene oxide blend nanofibers: Morphology and physicochemical properties.

The objective of this study was to fabricate and characterize Hydroxypropyl methylcellulose (HPMC) -based homogenous nanofibers by using electrospinning method. As the concentrations of the solutions increased, viscosity and electrical conductivity of the solutions increased. The morphology of the fibers changed from the beaded structure to the uniform fiber structure by increasing the concentrations of the solutions. Water vapor permeability (WVP) of electrospun HPMC nanofibers decreased with increasing polymer concentration. The shift in wavelengths, the change in intensity of FTIR peaks and melting point depression were the evidence of miscibility of HPMC/PEO blends. Nanofibers showing both melting temperature (Tm) and glass transition temperature (Tg) had semicrystalline structure. By combining PEO with HPMC, the thermal stability of nanofibers was increased. Hence, this study suggests homogenous biopolymer-based nanofibers with low WVP and high thermal stability which can have potential applications in food packaging field.

Influence of solution properties and pH on the fabrication of electrospun lentil flour/HPMC blend nanofibers.

Electrospinning is a method used in fiber production in which an electric force is applied to create jets of charged polymer solutions. The objective of this study was to obtain homogeneous nanofibers from lentil flour and hydroxypropyl methylcellulose (HPMC) blend by using electrospinning method. Distilled water was used as solvent. The effects of pH (7, 10 and 12), lentil flour concentration (1% and 2% (w/v)) and HPMC concentration (0.25%, 0.5% and 1% (w/v)) on solution properties and fiber morphology were investigated. When the pH was increased, the viscosity of the solutions containing 1% and 2% lentil flour decreased. Increasing the pH values caused an increase in the electrical conductivity. At pH value of 7, homogeneous nanofibers could not be obtained whereas fibers were perfectly homogeneous at alkaline pH values. Nanofiber diameter decreased with increase in pH when 2% lentil flour was used. On the other hand, diameter of fibers did not show any significant change with pH for 1% lentil flour. When the lentil flour concentration was increased, viscosity and fiber diameter increased at pH10. When HPMC concentration was increased, both viscosity and fiber diameter increased but electrical conductivity did not show any significant change. Average fiber diameters ranged between 198±4 and 254±5nm for solutions prepared with different lentil flour and HPMC concentrations at different pH values.

Effect of different flours on quality of legume cakes to be baked in microwave-infrared combination oven and conventional oven.

The objective of this study was to compare the quality of legume cakes baked in microwave-infrared combination (MW-IR) oven with conventional oven. Legume cake formulations were developed by replacing 10 % wheat flour by lentil, chickpea and pea flour. As a control, wheat flour containing cakes were used. Weight loss, specific volume, texture, color, gelatinization degree, macro and micro-structure of cakes were investigated. MW-IR baked cakes had higher specific volume, weight loss and crust color change and lower hardness values than conventionally baked cakes. Larger pores were observed in MW-IR baked cakes according to scanning electron microscope (SEM) images. Pea flour giving the hardest structure, lowest specific volume and gelatinization degree was determined to be the least acceptable legume flour. On the other hand, lentil and chickpea flour containing cakes had the softest structure and highest specific volume showing that lentil and chickpea flour can be used to produce functional cakes.

Rheology, particle-size distribution, and stability of low-fat mayonnaise produced via double emulsions.

In this study, the effects of the double emulsification method on the rheological properties, particle size, and stability of low-fat mayonnaise were studied. Different water-phase-to-oil ratios (2:8 and 4:6) of primary emulsions and different stabilizer types (sodium caseinate, xanthan gum, and lecithin-whey protein concentrate) were used to produce double-emulsified mayonnaise. As a control sample, mayonnaise was prepared conventionally. Sodium caseinate was found to be the most efficient stabilizer. In the presence of sodium caseinate, the stability and apparent viscosity of double-emulsified mayonnaise increased but their particle sizes decreased. It was found that flow behavior of double-emulsified and conventionally prepared mayonnaise could be described by the power law model. The double-emulsified mayonnaise samples were not different from the control samples in terms of stability and particle size. In addition, using the double emulsion method, it was possible to reduce the oil content of mayonnaise to 36.6%.

Microencapsulation of wheat germ oil.

Wheat germ oil (WGO) is beneficial for health since it is a rich source of omega-3, omega-6 and tocopherol. However, as it contains polyunsaturated fatty acids, it is prone to oxidation. The aim of this study was to encapsulate wheat germ oil and determine the effects of core to coating ratio, coating materials ratio and ultrasonication time on particle size distribution of emulsions and encapsulation efficiency (EE) and surface morphology of capsules. Maltodextrin (MD) and whey protein concentrate (WPC) at different ratios (3:1, 2:2, 1:3) were used as coating materials. Total solid content of samples was 40 % (w/w). Five core to coating ratios (1:8, 1:4, 1:2, 3:4, 1:1) were tried. Ultrasound was used at 320 W and 20 kHz for 2, 5, 10 min to obtain emulsions. Then, emulsions were freeze dried to obtain microcapsules. It was observed that, increasing WPC ratio in the coating resulted in higher encapsulation efficiency and smaller particle size. Microcapsules prepared with MD:WPC ratio of 1:3 were found to have higher EE (74.35-89.62 %). Increase in oil load led to decrease in EE. Thus 1:8 core to coating ratio gave better results. Increasing ultrasonication time also had a positive effect on encapsulation efficiency.

Comparison of microwave and ultrasound-assisted extraction techniques for leaching of phenolic compounds from nettle.

In this study, extraction of phenolic compounds from nettle by microwave and ultrasound was studied. In both microwave and ultrasound-assisted extractions, effects of extraction time (5-20 min for microwave; 5-30 min for ultrasound) and solid to solvent ratio (1:10, 1:20, and 1:30 g/mL) on total phenolic content (TPC) were investigated. Effects of different powers (50 % and 80 %) were also studied for ultrasound-assisted extraction. In microwave-assisted extraction, the optimum TPC of the extracts (24.64 ± 2.36 mg GAE/g dry material) was obtained in 10 min and at 1:30 solid to solvent ratio. For ultrasound-assisted extraction, the condition that gave the highest TPC (23.86 ± 1.92 mg GAE/g dry material) was 30 min, 1:30 solid to solvent ratio, and 80 % power. Extracts obtained at the optimum conditions of microwave and ultrasound were compared in terms of TPC, antioxidant activity (AA) and concentration of phenolic acids with conventional extraction and maceration, respectively. Microwave reduced extraction time by 67 %. AA of extracts varied between 2.95 ± 0.01 and 4.48 ± 0.03 mg DPPH/g dry material among four methods. Major phenolic compounds were determined as naringenin and chlorogenic acid in nettle.

Microwave-assisted hydrodistillation of essential oil from rosemary.

Effects of microwave assisted hydrodistillation (MAHD) and conventional hydrodistillation (HD) methods on yield, composition, specific gravity, refractive index, and antioxidant and antimicrobial activities of essential oil of Rosmarinus officinalis L were studied. The main aroma compounds of rosemary essential oil were found as 1,8-cineole and camphor. Trolox equivalent antioxidant capacity (TEAC) values for essential oils extracted by MAHD and HD were 1.52 mM/ml oil and 1.95 mM/ml oil, respectively. DPPH radical scavenging activity of the oils obtained by MAHD and HD were found as 60.55% and 51.04% respectively. Inhibitory effects of essential oils obtained by two methods on linoleic acid peroxidation were almost the same. Essential oils obtained by two methods inhibited growth of Esherichia coli O157:H7, Salmonella typhimurium NRRLE 4463 and Listeria monocytogenes Scott A with the same degree. However, inhibitory activity of essential oil obtained by MAHD on Staphylococcus aureus 6538P was stronger than that of obtained by HD (p < 0.05).

The effect of different formulations on physical properties of cakes baked with microwave and near infrared-microwave combinations.

The aim of this study was to determine the effect of different formulations on color and textural characteristics of different cakes during baking in microwave and near infrared-microwave combination ovens. For comparison, cakes were also baked in conventional ovens. Color and hardness for both types of baking schemes were found to be dependent on formulation. Cakes containing Simplesse, a fat replacer consisting mostly of whey protein, baked in microwave and near infrared-microwave combination ovens were found to be the firmest cakes.

Investigation of dielectric properties of different cake formulations during microwave and infrared-microwave combination baking.

Dielectric properties can be used to understand the behavior of food materials during microwave processing. Dielectric properties influence the level of interaction between food and high frequency electromagnetic energy. Dielectric properties are, therefore, important in the design of foods intended for microwave preparation. In this study, it was aimed to determine the variation of dielectric properties of different cake formulations during baking in microwave and infrared-microwave combination oven. In addition, the effects of formulation and temperature on dielectric properties of cake batter were examined. Dielectric constant and loss factor of cake samples were shown to be dependent on formulation, baking time, and temperature. The increase in baking time and temperature decreased dielectric constant and loss factor of all formulations. Fat content was shown to increase dielectric constant and loss factor of cakes.

Usage of enzymes in a novel baking process.

In this study, the effects of different enzymes (alpha-amylase, xylanase, lipase, protease) on quality of breads baked in different ovens (microwave, halogen lamp-microwave combination and conventional oven) were investigated. It was also aimed to reduce the quality problems of breads baked in microwave ovens with the usage of enzymes. As a control, bread dough containing no enzyme was used. Specific volume, firmness and color of the breads were measured as quality parameters. All of the enzymes were found to be effective in reducing the initial firmness and increasing the specific volume of breads baked in microwave and halogen lamp-microwave combination ovens. However, in conventional baking, the effects of enzymes on crumb firmness were seen mostly during storage. The color of protease enzyme added breads were found to be significantly different from that of the no enzyme and the other enzyme added breads in the case of all type of ovens.