Bor-Sen Chiou

Encapsulation of Plant Oils in Porous Starch Microspheres

Natural plant products such as essential oils have gained interest for use in pest control in place of synthetic pesticides because of their low environmental impact. Essential oils can be effective in controlling parasitic mites that infest honeybee colonies, but effective encapsulants are needed to provide a sustained and targeted delivery that minimizes the amount of active ingredient used. The present study reports the encapsulation of essential oils in porous microspheres that are within the size range of pollen grains and can be easily dispersed. The microspheres were made by pumping an 8% aqueous high-amylose starch gelatinous melt through an atomizing nozzle. The atomized starch droplets were air-classified into two fractions and collected in ethanol. The size range for each fraction was measured using a particle size analyzer. The mean particle size for the largest fraction was approximately 100 microm with a range from 5 microm to over 300 microm. Part of the reason for the large particle size was attributed to the merging of smaller particles that impinged upon each other before they solidified. The smaller fraction of spheres had a mean particle size of approximately 5 microm. The starch-based porous microspheres were loaded with 16.7% (w/w) essential oils including thymol (5-methyl-2-isopropylphenol), clove, origanum, and camphor white oil. The essential oils appeared to be largely sequestered within the pore structure, since the spheres remained a free-flowing powder and exhibited little if any agglomeration in spite of the high loading rate. Furthermore, SEM micrographs verified that the pore structure was stable, as evidenced by the persistence of pores in spheres that had first been loaded with essential oils and then had the oil removed by solvent extraction. Thermal gravimetric analyses were consistent with a loading rate at predicted levels.

Radical Graft Polymerization of an Allyl Monomer onto Hydrophilic Polymers and Their Antibacterial Nanofibrous Membranes

Hydrophilic poly (vinyl alcohol-co-ethylene) (PVA-co-PE) copolymers with 27 mol %, 32 mol % and 44 mol % ethylene were functionalized by melt radical graft copolymerization with 2,4-diamino-6-diallylamino-1,3,5-triazine (NDAM) using reactive extrusion. This functionalization imparts antibacterial properties. The covalent attachments of the NDAM as side chains onto the PVA-co-PE polymer backbones were confirmed. The effects of initiator concentrations and ethylene contents in PVA-co-PE polymers on grafting of NDAM were studied. The chain scissions of PVA-co-PE polymers during reactive extrusion were investigated by monitoring changes in the melt torque and FTIR spectra. The NDAM grafted PVA-co-PE polymers were successfully fabricated into hydrophilic nanofibers and nanofibrous membranes with sufficient surface exposure of the grafted NDAM. The hydrophilicity of the PVA-co-PE polymers and the large specific surface area offered by the nanofiber membranes significantly facilitated the chlorine activation process, enhanced the active chlorine contents of the grafted PVA-co-PE nanofiber membranes, and therefore led to their superior antibacterial properties.

Biobased adhesives, gums, emulsions, and binders: current trends and future prospects

Biopolymers derived from renewable resources are an emerging class of advanced materials that offer many useful properties for a wide range of food and nonfood applications. Current state of the art in research and development of renewable polymers as adhesives, gums, binders, and emulsions is the subject of this review. Much of the focus will be on major biopolymers such as starch, proteins, lignin, oils, and their derivatives found in both natural and modified forms, but other biopolymers of promising commercial interest will also be included where warranted. Polymers produced in nature are remarkably diverse in their chemistry, thermomechanical properties, rheology, plasticity, and chemical reactivity. In particular, their capacity to undergo a wide array of chemical modifications yields materials with tailored properties suitable for use as adhesives, gums, coatings, emulsions, and binders. Many such materials are now widely used in commercial products like building materials, lubricants, sealants, coatings, bonding aids, pharmaceuticals, paper, glues, flocculants, processed and frozen foods, as well as tissue engineering and bone repair products. This review provides a general overview of biobased polymers highlighting their source, availability, properties, and usage in industrial products along with the future prospects, challenges, and opportunities they offer.

Torrefaction of pomaces and nut shells.

Apple, grape, olive, and tomato pomaces as well as almond and walnut shells were torrefied at different temperatures and times in a muffle furnace. The fiber content and thermal stability of the raw byproducts were examined and the moisture and ash contents, elemental composition, and gross calorific values of the raw and torrefied samples were characterized. Response surface methodology and a central composite design were used to examine the effects of temperature and time on mass and energy yields of the torrefied byproducts. Raw apple pomace had the highest hemicellulose content, whereas raw grape pomace had the highest lignin content. Raw tomato pomace had the highest gross calorific value because of its high carbon content. Temperature had a larger effect on mass and energy yields than time. Grape pomace generally had the highest mass and energy yields. Also, energy yields of the byproducts could be predicted from mass loss values.

Physical and Antibacterial Properties of Açaí Edible Films Formulated with Thyme Essential Oil and Apple Skin Polyphenols

UNLABELLED Thyme essential oil (TEO) and apple skin polyphenols (ASP) are natural compounds considered as generally recognized as safe by FDA, with biological effects against bacteria and fungi. This work aimed to evaluate physical and antimicrobial properties of açaí edible films formulated with TEO and ASP at 3% and 6% (w/w) individually or combined at 3% (w/w) each. Physical properties studied include mechanical resistance, water vapor permeability (WVP), color, and thermal resistance. Antimicrobial activity against Listeria monocytogenes was determined using the overlay diffusion test. Addition of ASP resulted in improved mechanical properties. TEO at 6% (w/w) resulted in increased elongation. ASP films had significant higher WVP than control film. ASP films were lighter and had more red color than other films. Incorporation of ASP resulted in improved film thermal stability, whereas TEO caused rapid thermal decomposition. Presence of clusters was observed on the surface of films. Addition of ASP resulted in a smoother surface, whereas addition of TEO led to the formation of crater-like pits on the film surface. Açaí edible film incorporated with 6% (w/w) TEO presented the highest antimicrobial activity. However, both antimicrobials are necessary in the açaí films in order to obtain edible films with suitable physical-mechanical properties. The results of the present study showed that TEO and ASP can be used to prepare açaí edible films with adequate physical-mechanical properties and antimicrobial activity for food applications by direct contact. PRACTICAL APPLICATION Developed açaí edible films presented antimicrobial activity against L. monocytogenes and good physical-mechanical properties, showing the potential use of açaí edible films in food preservation.

Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers.

Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were examined for the electrospun samples. The electrospun PVA samples generally had thinner and more uniform fibers than the electrospun PLA samples. For the PVA samples, an increase in total solids content and PVA to gelatin ratio generally resulted in higher average fiber diameter values and wider diameter distributions. Pollock gelatin in both types of electrospun samples remained amorphous. The PVA in electrospun samples had comparable melting temperatures to that of neat PVA, whereas the PLA in electrospun samples had slightly lower melting temperatures than that of neat PLA. Also, the PLA in electrospun samples had crystallization temperatures approximately 30 °C lower than that in neat PLA. This was due to better alignment of PLA chains during electrospinning, which resulted in the chains being more readily crystallized at lower temperatures. In addition, the electrospun PVA samples completely dissolved in water at room temperature after soaking for one day, whereas the electrospun PLA samples remained intact even after soaking for three days.

Vitamin D-fortified chitosan films from mushroom waste

Brown mushroom (Agaricus bisporus) stalk bases from mushroom waste were treated with UV-B light to rapidly increase vitamin D2 content. Chitin was also recovered from this waste and converted into chitosan by N-deacetylation. FTIR spectra showed that the mushroom chitosan were similar to chitosan from animal sources. Chitosan films were prepared using high molecular weight (HW), low molecular weight (LW) and fungal chitosan. UV-B treated mushroom particles were also incorporated into fungal chitosan films. The fungal chitosan films showed similar density, porosity and water vapor barrier properties to the LW and HW chitosan films. However, fungal chitosan films were more hydrophobic and less flexible than the LW and HW chitosan films. Addition of mushroom particles did not significantly affect mechanical or water barrier properties of the fungal chitosan films.

Solution Blow Spinning of Food-Grade Gelatin Nanofibers

The primary advantage of nanofibers over larger diameter fibers is the larger surface area to volume ratio. This study evaluated solution blow spinning (SBS) processing conditions for obtaining food-grade gelatin nanofibers from mammalian and fishery byproducts, such as pork skin gelatins (PGs) and high molecular weight fish skin gelatin (HMWFG). HMWFG had a highest intact collagen structure compared to PGs. PGs with different Bloom values, solution viscosities, and surface tensions were compared with HMWFG for their ability to produce nanofibers through SBS. Only HMWFG fibers were obtained irrespective of processing conditions, which looked like fluffy cotton candy. HMWFG nanofibers had round morphologies with a narrower diameter distribution and lower average fiber diameter (AFD) under medium gelatin concentrations, medium air pressures, and medium feed rates. The highest glass transition temperature (Tg ) values were obtained at medium concentrations, medium air pressure, and either high or low feed rate. The thinnest HMWFG nanofibers with an AFD of 80.1 nm and the highest Tg value of 59.0 °C could be formed by combining a concentration of 17.6% (w/v), an air pressure of 0.379 MPa, and a feed rate of 0.06 mL/min from the response surface analysis. HMWFG Brunauer, Emmett, and Teller surface area increased from 221 to 237 m2 /g, indicating their potential applicability for active compound carrier.

Preparation of Zein Fibers Using Solution Blow Spinning Method

Zein fibers were successfully fabricated via solution blow spinning (SBS) using acetic acid as solvent. Surface tension, viscosity and modulus of zein solutions were respectively determined by force tensiometer and rheometer. Increases of these properties were observed with an increase of concentration from 20% to 35% (w/w). The fabrication conditions of zein fibers were initially investigated as a function of zein concentration (25% to 35% w/w), feed rate (0.04 to 0.1 mL/min) and air pressure (0.28 to 0.62 MPa). The average fiber diameter (AFD) ranged from 174 to 9595 nm based on scanning electron microscopy (SEM). A Box-Behnken experimental design (BBD) was further performed to identify and quantify the significance of above parameters. The statistical analysis showed that the linear coefficient of concentration, the quadratic term of concentration as well as the interaction between concentration and air pressure were demonstrated statistically significant. Optimal conditions, with an AFD of 138 nm, could be obtained in the SBS of zein fibers by combining a concentration of 23% (w/w), a feed rate of 0.04 mL/min and an air pressure of 0.38 MPa. The moisture sorption capacity of fibers increased slightly as AFD decreased from ∼550 to ∼200 nm, with an increase of BET surface area from 116.5 to 140.0 m2 /g.

Activated carbons prepared by physical activation from different pretreatments of amazon piassava fibers

ABSTRACT This study aimed to evaluate the effect of different pretreatments of Amazon piassava (Leopoldinia piassaba) fibers on microstructure, thermal, and physical properties of the ensuing activated carbons (ACs). ACs were prepared from untreated and pretreated piassava fibers by physical activation using CO2 at 800°C. Pretreatments include: mercerization, corona discharge, and removal of extractives. Scanning electron micrographs showed the formation of nanoscale pores after the activation process of the charcoal. ACs from pretreated piassava fibers presented lower crystallinity and higher thermal stability than the untreated sample. ACs from Amazon piassava fibers are potential adsorbent materials for a myriad of applications.