Active Fish Gelatin/Chitosan Blend Film Incorporated with Guava Leaf Powder Carbon Dots: Properties, Release and Antioxidant Activity.

Active packaging is an innovative approach to prolonge the shelf-life of food products while ensuring their quality and safety. Carbon dots (CDs) from biomass as active fillers for biopolymer films have been introduced to improve their bioactivities as well as properties. Gelatin/chitosan (G/C) blend films containing active guava leaf powder carbon dots (GL-CDs) at various levels (0-3%, w/w) were prepared by the solvent casting method and characterized. Thickness of the control increased from 0.033 to 0.041 mm when 3% GL-CDs were added (G/C-CD-3%). Young's modulus of the resulting films increased (485.67-759.00 MPa), whereas the tensile strength (26.92-17.77 MPa) and elongation at break decreased (14.89-5.48%) as the GL-CDs' level upsurged (p < 0.05). Water vapor barrier property and water contact angle of the film were enhanced when incorporated with GL-CDs (p < 0.05). GL-CDs had a negligible impact on film microstructure, while GL-CDs interacted with gelatin or chitosan, as determined by FTIR. The release of GL-CDs from blend films was more pronounced in water than in alcoholic solutions (10-95% ethanol). The addition of GL-CDs improved the UV light barrier properties and antioxidant activities of the resultant films in a dose-dependent manner. Thus, GL-CD-added gelatin/chitosan blend films with antioxidant activities could be employed as potential active packaging for the food industry.

Storage stability of Asian seabass oil-in-water Pickering emulsion packed in pouches made from electrospun and solvent casted bilayer films from poly lactic acid/chitosan-gelatin blend containing epigallocatechin gallate.

Bilayer pouches were fabricated with chitosan (CS)-fish gelatin (FG) mixture containing epigallocatechin gallate (EGCG) deposited over the poly lactic acid (PLA) film through solvent casting and electrospinning techniques. Pickering emulsions (PE) of Asian seabass depot fat oil stabilized by zein colloidal particles were packed in bilayer pouches and stored at 28 ± 2 °C. The PE packed in pouch containing EGCG had higher emulsion and oxidative stability after 30 days of storage as witnessed by the smaller droplet size and lower values of thiobarbituric acid reactive substances, peroxide, conjugated diene and volatile compounds in comparison with control (PE packed in monolayer PLA pouch) (P < 0.05). EGCG incorporated pouch retained more linoleic acid (C18:2 n-6) and linolenic acid (C18:3 n-9) in emulsion than PLA pouch. Therefore, pouch from bilayer PLA/CS-FG films comprising EGCG could serve as active packaging and extended the shelf life of Pickering emulsion.

Packaging films based on biopolymers from seafood processing wastes: Preparation, properties, and their applications for shelf-life extension of seafoods-A comprehensive review.

Biopolymers derived from seafood processing byproducts are used to prepare active and biodegradable films as the packaging of food products. These films possess bioactivities to enhance the shelf life of packed foods by proactively releasing antimicrobial/antioxidative agents into the foods and providing sufficient barrier properties. Seafood processing byproducts are an eminent source of valuable compounds, including biopolymers and bioactive compounds. These biopolymers, including collagen, gelatin, chitosan, and muscle proteins, could be used to prepare robust and sustainable food packaging with some antimicrobial agents or antioxidants, for example, plant extracts rich in polyphenols or essential oils. These active packaging are not only biodegradable but also prevent the deterioration of packed foods caused by spoilage microorganisms as well as chemical deterioration. Seafood discards have a promising benefit for the development of environmentally friendly food packaging systems via the appropriate preparation methods or techniques. Therefore, the green packaging from seafood leftover can be better exploited and replace the synthetic counterpart.

Evaluating Kinetics of Convection Drying and Microstructure Characteristics of Asian Seabass Fish Skin without and with Ultrasound Pretreatment.

Convection drying in combination with ultrasound pretreatment has emerged as a promising technology for seafood manufacturing. The primary objective of this research was to model the mass transfer process of Asian seabass (Lates calcarifer) fish skin without and with ultrasound pretreatment during convection drying at different temperatures (45, 55, and 65 °C). Additionally, the study aimed to examine the impact of ultrasound pretreatment and temperatures on the drying characteristics and specific energy consumption for drying of Asian seabass fish skin. Seven semi-theoretical models, namely Lewis, Page, modified Page, Vega-Lemus, Verma, Henderson and Pabis, and two-term models, were employed to characterize the moisture transfer process. The results of the study indicated a decrease in the moisture content as the drying time increased at different drying temperatures. Higher drying temperatures were associated with an increased drying rate. Among the mathematical models tested, the modified Page model provided a satisfactory description of the thin-layer drying characteristics of fish skin. Fick's law of diffusion was utilized to determine the effective moisture diffusivities. Comparing the drying of fish skin without (SS) and with ultrasound pretreatment (US-SS), the drying of the latter generally showed higher Deff values. The temperature dependence of the effective diffusivity coefficient was well described by the Arrhenius-type model. An increase in the drying temperature resulted in an increment of the effective moisture diffusivity. In general, the skin pretreated using ultrasound had a reduced drying time, by up to 28%. Additionally, this approach contributed to an approximate 22% reduction in the specific energy consumption, concurrently enhancing the energy efficiency. The microstructure analysis showed that fresh and dried US-SS samples had a more open structure and higher porosity, in comparison to the corresponding SS samples. These findings contribute to the knowledge on the application of ultrasound as the pretreatment of fish skin before drying and provide valuable insights for the development of potential drying techniques in the seafood industry.

Covalently phenolated-ß-lactoglobulin-pullulan as a green halochromic biosensor efficiency monitored Barramundi fish's spoilage.

The effect of the covalent binding between anthocyanins extracted from purple potato peels and beta-lactoglobulin (ß-Lg) on its ability to fabricate a green/smart halochromic biosensor combined with pullulan (Pul) was studied. The physical, mechanical, colorimetry, optical, morphological, stability, functionality, biodegradability, and applicability of ß-Lg/Pul/Anthocyanin biosensors to monitor the Barramundi fish's freshness during storage were entirely evaluated. The docking and multispectral results proved that ß-Lg could be successfully phenolated with anthocyanins and subsequently interacted with Pul via H-bonding and other forces which mainly subsequently form the smart biosensors. Phenolation with anthocyanins significantly heightened the mechanical, moisture resistance, and thermal steadiness of ß-Lg/Pul biosensors. Anthocyanins also nearly duplicated the bacteriostatic and antioxidant activities of ß-Lg/Pul biosensors. The biosensors changed the color associated with the loss in freshness of the Barramundi fish, mostly due to the ammonia production and pH-alteration throughout fish deterioration. Most importantly, ß-Lg/Pul/Anthocyanin biosensors are biodegradable and decomposed within ∼30 d of simulated environmental circumstances. Overall, ß-Lg/Pul/Anthocyanin smart biosensors could minimize the usage of plastic packaging materials and employ to monitor the freshness of stored fish and fish-stuffs.

Polylactic Acid Film Coated with Electrospun Gelatin/Chitosan Nanofibers Containing Betel Leaf Ethanolic Extract: Properties, Bioactivities, and Use for Shelf-Life Extension of Tilapia Slices.

Gelatin/chitosan solutions incorporated with betel leaf ethanolic extract (BLEE) at varying concentrations were electrospun on polylactic acid (PLA) films. Nanofibers with different morphologies, as indicated by scanning electron microscopy (SEM), were formed after solutions of gelatin/chitosan with and without BLEE were electrospun on PLA films at a constant voltage (25 kV) and a feed rate of 0.4 mL/h. Beaded gelatin/chitosan nanofibers (GC/NF) were found, particularly when high concentrations of BLEE were encapsulated. PLA films coated with GC/NF, and with BLEE added, showed antioxidant and antibacterial activities, which were augmented by increasing BLEE concentrations. Lower water vapor permeability and enhanced mechanical properties were achieved for GC/NF-coated PLA film (p < 0.05). Microbial growth and lipid oxidation of Nile tilapia slices packaged in PLA film coated with GC/NF containing 2% BLEE were more retarded than those packaged in low-density polyethylene (LDPE) bags over refrigerated storage of 12 days. Based on microbial limits, the shelf-life was escalated to 9 days, while the control had a shelf-life of 3 days. Therefore, such a novel film/bag could be a promising active packaging for foods.

Characteristics and seal ability of blend films based on chicken protein isolate and fish skin gelatin.

Blend films from chicken protein isolate (CPI) and fish skin gelatin (FSG) at various CPI/FSG ratios (100:0, 80:20, 70:30, 60:40, 0:100), prepared at pH 3 or 11 were characterized. At the same pH, tensile strength (TS) of CPI/FSG films was higher than CPI and FSG films, and CPI/FSG film (60:40) had highest TS. Moreover, elongation at break (EAB) of blend films increased as FSG content augmented. EAB of CPI film and CPI/FSG (80:20) film was similar for both pHs. CPI films generally possessed higher water vapor permeability (WVP), light barrier property and b*-value than FSG counterpart. CPI films prepared at both pHs were not sealable. Nevertheless, addition of FSG improved sealing ability of blend films. At the same CPI/FSG ratio, seal strength and seal efficiency were lower for films prepared at pH 11. Moreover, higher TS and b*-value were gained, compared to those of films prepared at pH 3. Less cracks on surface and cross-section appeared for CPI/FSG films as revealed by scanning electron microscopy images, compared to CPI and FSG films. Therefore, incorporation of FSG up to 40% into blend film was able to improve mechanical properties, WVP, and sealing ability of blend films.

Liposomes loaded with betel leaf (Piper betle L.) ethanolic extract prepared by thin film hydration and ethanol injection methods: Characteristics and antioxidant activities.

Betel leaf ethanolic extract (BLEE), which was dechlorophyllized by sedimentation process was loaded in liposomes at 1 and 2% (w/v) concentrations using two different methods, namely thin film hydration (TF) and ethanol injection (EI) methods. Liposomes loaded with 1% BLEE and prepared by TF method (BLEE/L-T1) had the smallest particle size and paler color than BLEE/L-E1, BLEE/L-E2, and BLEE/L-T2 (p < .05). BLEE/L-T1 also showed strong stability as judged by its lowest zeta potential and polydispersity index. The highest encapsulation efficiency (EE) and lowest releasing efficiency (RE) were also found with BLEE/L-T1. No significant difference (p > .05) in the antioxidant activities was detected between the BLEE-loaded liposomes and BLEE solutions, indicating that encapsulation had no adverse effect on BLEE antioxidant potency. BLEE/L-T1 showed higher antioxidant stability than unencapsulated BLEE at the equivalent amount based on EE (BLEE/U-T1) during in vitro gastrointestinal tract digestion system. Therefore, BLEE/L-T1 could be an efficient delivery system for improving stability of antioxidant activities of BLEE. PRACTICAL APPLICATIONS: Despite the many benefits of betel leaf ethanolic extract, it still has some distinctive odor and slightly greenish color as well as instability induced by environment factors, which can limit applications in foods. Encapsulation of the betel extract in liposomes can be a good approach to mask its undesirable color and odor and to augment its antioxidant stability. Liposomal technology can be used to load betel leaf extract. However, different methods have been implemented to prepare liposomes that exhibit varying encapsulation efficacy as well as bioactivities. Thin film hydration method was shown to yield the liposome with better physical characteristics, higher encapsulation efficiency, slower release, and higher antioxidant stability than the ethanol injection method. Therefore, the thin film hydration method could be adopted to prepare stable liposomes loaded with betel leaf extract that possess antioxidant activity suitable for food applications.

Effect of Psyllium (Plantago ovata Forks) Husk on Characteristics, Rheological and Textural Properties of Threadfin Bream Surimi Gel.

Effects of psyllium (Plantago ovata) husk powder (PHP) at various concentrations (0, 1, 2, 3 and 4%, w/w) on gelling properties of surimi from threadfin bream (Nemipterus sp.) were investigated. The addition of 1% PHP resulted in the highest increase (50%) in the breaking force (BF) of surimi gel (S), compared to that of the control gel (CON; without PHP). Lower BF was obtained for gel incorporated with PHP at the higher levels (2-4%) (p < 0.05). On the other hand, deformation (DF) was decreased with the addition of PHP at all levels compared to the CON gel. The whiteness and expressible moisture content of gels were decreased with augmenting levels of PHP (p < 0.05). Protein patterns revealed that PHP at all concentrations did not affect the polymerization of the myosin heavy chain. A loss in the elasticity of the gel was attained with the addition of PHP as indicated by decreased storage modulus (G'). A finer and more compact network was detected in gels containing 1 and 2% PHP than that found in the CON. FTIR spectra suggested that the addition of PHP influenced the secondary structure as well as functional groups of myofibrillar proteins. Based on the sensory evaluation, the surimi containing PHP at 1-3% showed a similar overall likeness score to the CON. Therefore, PHP at the optimum level could improve the gelling properties of the threadfin bream surimi with high acceptability.

Physical and chemical characteristics of Asian sea bass bio-calcium powders as affected by ultrasonication treatment and drying method.

The effects of ultrasonication and drying method on particle size and other product characteristics of bio-calcium powder from Asian sea bass (Lates calcarifer) backbone were investigated. Ultrasonication was performed at different amplitudes (60%, 70%, and 80%) for varying periods (15 and 30 min). Ultrasonication at higher amplitudes for a longer time reduced the powder particle size more effectively (p < .05), but had no impact on zeta potential (p > .05). The bio-calcium powder ultrasonicated at 70% amplitude for 15 min had the smallest particle size (3.38 µm) when compared to the control (28.85 µm). When the ultrasonicated bio-calcium was subjected to drying, freeze-drying produced powders with higher calcium solubility but lower whiteness than hot air (tray) drying. The results suggest that the ultrasonication is a potential suitable method to reduce the size of bio-calcium powders, while the drying method slightly affected the product characteristics. The bio-calcium powder could serve as a suitable functional ingredient for food fortification aimed at improving the calcium bioavailability. Particle size of bio-calcium powder from fishbone could affect the mouth feel and calcium solubility when used for food product fortification. This work showed that ultrasonication could be used to obtain up to 10-fold reduction in the particle size of fishbone bio-calcium powders, which promotes increased calcium solubility when subjected to simulated gastrointestinal tract digestion. Few differences in characteristics of the bio-calcium powder were observed for freeze-dried and hot air-dried samples. Thus, an economical, safe, and fast process can be implemented for the production of small particle size bio-calcium powder from fishbone.

Effect of proteases and alcohols used for debittering on characteristics and antioxidative activity of protein hydrolysate from salmon frames.

Protein hydrolysates were obtained from salmon frame using Alcalase or Flavourzyme at 3% (w/w protein) for 180 min. Protein hydrolysates prepared using Alcalase (HA) and Flavourzyme (HF) had DH and yield of 25.1-26.9% and 28.5-32.3 g/100 g sample, respectively. HF showed lower bitterness score (5.78) than that of HA (8.68) (P < 0.05). When HA and HF were further subjected to debittering with 2-butanol or isopropanol, the recovery of 77.88-81.60% was obtained (P < 0.05). HF and HA debittered with 2-butanol possessed less bitterness score, 3.60 and 3.77, respectively (P < 0.05). Surface hydrophobicity of 81.4 and 124.8 was attained when HF and HA were debittered with 2-butanol (P < 0.05). Selected debittered hydrolysates, produced using Flavourzyme, followed by fractionation using 2-butanol (HF-B) contained glutamic acid/glutamine (15.14 g/100 g), aspartic acid/asparagine (10.07 g/100 g) and glycine (9.30 g/100 g) as the predominant amino acids. HF-B had the decreased ABTS radical scavenging activity and metal chelating activity. A280 of peptides separated by gel filtration was lowered to some extent and coincided with the lower bitterness score and surface hydrophobicity. Thus, debittered protein hydrolysate from salmon frame could serve as a nutritive ingredient at high levels in health promoting foods.

Chemical, physical, rheological and sensory properties of biscuit fortified with protein hydrolysate from cephalothorax of Pacific white shrimp.

Chemical, physical, rheological and sensory properties of biscuits fortified with shrimp protein hydrolysate powder (SHP) at various levels (0-7.5%, flour substitution) were investigated. The addition of 7.5% SHP slightly decreased diameter of biscuit and thickness was decreased as SHP at levels of 2.5-7.5% was incorporated. Hardness and fracturability of biscuit decreased as the levels of SHP was higher than 1.25 and 2.5%, respectively. Surface of biscuit became more reddish and yellowish as SHP was added. The addition of 5% SHP increased likeness score of resulting biscuit. Fortification of SHP affected the viscoelastic properties of dough. Deformation resistance and strength of dough decreased with increasing levels of SHP. Additional volatile compounds including aldehyde, ketone, alkane and ether, were detected when 5% SHP was incorporated, thus more likely contributing to odor and flavor of resulting biscuit. The addition of 5% SHP into biscuit resulted in the increased protein content with reduction of carbohydrate. Therefore, the biscuit could be fortified with 5% SHP and had higher nutritional value and increased sensory properties.

Ultrasound-Assisted Extraction of Chitosan from Squid Pen: Molecular Characterization and Fat Binding Capacity.

Chitosan from squid (Loligo formosana) pens were prepared and characterized. First, ultrasonication condition was optimized for deproteinization of squid pens using central composite design (CCD) of response surface methodology (RSM). Squid pens were ultrasonicated at amplitude 69% for 41.46 min at the solid/solvent ratio of 1:18 yielded 34% (w/w) chitin with the lowest remaining protein. Therefore, ultrasonication effectively reduced the extraction time for chitin production from squid pens as compared to traditional method (5 hr). When the resultant chitin was subjected to deacetylation at different temperatures and times, yield and degree of deacetylation (DDA) of chitosan were in the range of 50% to 65% (w/w) and 78% to 90%. Intrinsic viscosity and molecular weight (MW) of chitosan were in the range of 3.2 to 6.52 dL/g and 1.2 × 105 to 3.2 × 105 Da, respectively. All the chitosans with different DDA were able to bind oil droplets under the mimicked pH condition of gastrointestinal tract. Chitosan produced by deacetylation at 130 °C for 2 hr (CH130-2) showed the optimum yield (54%) and had medium MW (1.5 × 105 Da). DDA of CH130-2 determined using 1 H-NMR was 89%, which was similar to that (87%) obtained from FTIR. XRD results showed destruction of chitin structure and decreased crystallinity index from 55% to 27% after deacetylation. CH130-2 stabilized the emulsion under the simulated gastrointestinal conditions. Therefore, it could be used as dietary fiber to control the adsorption of fat/oil in the human digestive tract. PRACTICAL APPLICATION: Chitin and chitosan are marketable products manufactured from crustacean shells. However, extraction of chitin is time consuming. Ultrasonication has been used for extraction of various biomolecules from different sources. It effectively lowers the processing time and enhances extraction yield. Therefore, application of ultrasonication with optimized condition using RSM could reduce extraction time and enhance yield of chitin from squid pen. Chitin from squid pen could be further converted to chitosan with high DDA. Chitosan was able to act as a dietary fiber and reduce fat absorption in gastrointestinal tract. Thus, this information is of benefit for squid processing industry to exploit squid pen, a processing byproduct.

Characteristics and gelling properties of gelatin from goat skin as affected by drying methods.

Characteristics and gel properties of spray-dried goat skin gelatin (SDGG) and freeze-dried counterpart (FDGG) were determined, in comparison with commercial bovine gelatin (BG). SDGG gel had the similar gel strength to FDGG gel and their gel strengths were higher than that of BG gel. SDGG gel showed slightly higher a* and b* values as well as the higher solution turbidity than those of FDGG. Both SDGG and FDGG solutions could set at room temperature (25-28 °C) within 18.52-19.30 min and showed the gelling and melting temperatures of 25.14-25.23 and 34.09-34.18 °C, respectively. Gels from SDGG and FDGG had the denser structure with smaller voids than that from BG. Therefore, drying methods affected the characteristics and gel properties of gelatin from goat skin to some degree.

Influence of palm oil and glycerol on properties of fish skin gelatin-based films.

Properties of fish skin gelatin film incorporated with palm oil at 50 and 75 % (w/w) as affected by glycerol at 0-30 % (w/w) were investigated. Increases in water vapour permeability and elongation at break along with decrease in tensile strength were noticed when levels of glycerol were increased (p < 0.05). Decrease in L*- and a*-values with coincidental increase in b*- and ΔE*-values were observed in emulsified films when amount of palm oil incorporated increased (p < 0.05). Light transmittance of all films increased as glycerol levels were increased (p < 0.05). FTIR results suggested that the protein-protein interaction in film matrix decreased when palm oil was incorporated. Films added with palm oil had lower glass transition and degradation temperatures than control films. The addition of 75 % palm oil and 10 % glycerol improved water vapour barrier property of fish skin gelatin films without drastic alteration of mechanical properties.

Characteristics and Gel Properties of Gelatin from Goat Skin as Influenced by Alkaline-pretreatment Conditions.

Characteristics and properties of gelatin from goat skin pretreated with NaOH solutions (0.50 and 0.75 M) for various times (1 to 4 days) were investigated. All gelatins contained α-chains as the predominant component, followed by ß-chain. Gelling and melting temperatures of those gelatins were 23.02°C to 24.16°C and 33.07°C to 34.51°C, respectively. Gel strength of gelatins increased as NaOH concentration and pretreatment time increased (p<0.05). Pretreatment for a longer time yielded gelatin with a decrease in L*-value but an increase in b*-value. Pretreatment of goat skin using 0.75 M NaOH for 2 days rendered the highest yield (15.95%, wet weight basis) as well as high gel strength (222.42 g), which was higher than bovine gelatin (199.15 g). Gelatin obtained had the imino acid content of 226 residues/1,000 residues and the gelatin gel had a fine and ordered structure. Therefore, goat skin gelatin could be used as a potential replacer of commercial gelatin.

Emulsion stability and properties of fish gelatin-based films as affected by palm oil and surfactants.

BACKGROUND: Gelatin films exhibit the poor water vapour barrier properties. The use of palm oil, which is abundant and available in Thailand, can be a means to lower water vapour migration. To disperse oil in film-forming dispersion (FFD), a surfactant along with appropriate homogenization is required. The study aimed to investigate the influence of palm oil level and surfactants in the absence or presence of glycerol on characteristics of FFD and resulting gelatin films. RESULTS: Similar oil droplet sizes, both d32 and d43 values, of FFD containing soy lecithin were observed, regardless of palm oil level used (P > 0.05). FFD with Tween-20 had larger droplet size as the levels of oil increased (P < 0.05). After 12 h storage, slight increases in d32 and d43 were noticeable in all FFD samples. When the films were determined, lower water vapour permeability (WVP) and tensile strength (TS) but higher elongation at break (EAB) were obtained as palm oil level increased (P < 0.05), regardless of glycerol and surfactant used. Films without glycerol had lower WVP and EAB with higher TS than those containing 300 g kg(-1) glycerol (P < 0.05). No differences in WVP and mechanical properties were found between films containing both surfactants (P > 0.05). CONCLUSION: FFD containing 500 or 750 g kg(-1) palm oil using soy lecithin as a surfactant in the presence of 300 g kg(-1) glycerol had the enhanced homogeneity and stability of oil droplets. The resulting gelatin film had the improved water vapour barrier properties. © 2015 Society of Chemical Industry.

Characteristics and gel properties of gelatin from goat skin as affected by pretreatments using sodium sulfate and hydrogen peroxide.

BACKGROUND: Goat skin can be used as an alternative raw material for gelatin production, in which pretreatment conditions can determine the characteristics or properties of the resulting gelatin. The present study aimed to investigate the effect of pretreatment using sodium sulfate (Na2SO4) and hydrogen peroxide (H2O2) on properties of goat skin gelatin. RESULTS: Pretreatment of skin using Na2SO4 (0-1 mol L(-1)) increased the yield of gelatin in a concentration-dependent manner. When skins with prior Na2SO4 treatment were bleached using H2O2 (0-2 mol L(-1)), the resulting gelatin showed higher yield and gel strength than those without prior Na2SO4 treatment. All gelatins had α-chain as a major component, followed by ß-chain. The degradation induced by H2O2 was lower in gelatin with prior Na2SO4 treatment. L* values increased with increasing H2O2 concentrations (P < 0.05) due to the bleaching effect of H2O2. With Na2SO4 and H2O2 pretreatments, gelatin gel had a finer and more ordered microstructure. Gelatin had an imino acid content of 217 residues/1000 residues with gelling and melting temperature of 22.49 and 32.28 °C, respectively. CONCLUSION: The optimal pretreatment conditions for gelatin extraction from goat skin included soaking the skin in 0.75 mol L(-1) NaOH, followed by treatment using 0.75 mol L(-1) Na2SO4 and subsequent bleaching with 2 mol L(-1) H2O2. This resulted in gelatin with superior quality to the untreated counterpart.

Properties and characteristics of nanocomposite films from tilapia skin gelatin incorporated with ethanolic extract from coconut husk.

Impacts of ethanolic extract from coconut husk (EECH) at 0-0.4 % (w/w, on protein basis) on properties of films from tilapia skin gelatin and gelatin/Cloisite Na(+) nanocomposite films were investigated. Young's Modulus, tensile strength and elongation at break of both films decreased with addition of EECH (P < 0.05). The lowest water vapour permeability (WVP) was obtained for gelatin film containing 0.05 % EECH (w/w) (P < 0.05). Nevertheless, the nanocomposite film showed the lowest WVP when incorporated with 0.4 % EECH (w/w) (P < 0.05). Generally, L*- value (lightness) decreased and a*- value (redness) of films increased (P < 0.05) with increasing levels of EECH, regardless of nanoclay incorporation. Transparency of both films generally decreased as the level of EECH increased (P < 0.05). Intercalated or exfoliated structure of nanocomposite films was revealed by wide angle X-ray diffraction (WAXD) analysis. Based on scanning electron microscopic (SEM) analysis, the rougher surface was found when EECH was added. EECH had varying impact on thermal stability of films as revealed by thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. Thus, the incorporation of EECH determined the properties of both gelatin film and nanocomposite film in which the improved water vapour barrier property could be obtained.

Effects of pHs on properties of bio-nanocomposite based on tilapia skin gelatin and Cloisite Na+.

Effects of various pHs (4-8) of film forming suspensions (FFS) on the properties of nanocomposite film based on tilapia skin gelatin and hydrophilic nanoclay (Cloisite Na(+)) were investigated. Intercalated/exfoliated structure of nanocomposite films was revealed by WAXD analysis. Young's Modulus (YM) and tensile strength (TS) of nanocomposite films increased up to pH 6 (P<0.05). Nevertheless, the further increases in pH levels resulted in the decreases in both YM and TS (P<0.05). The highest water vapour barrier property of the film was observed when the pH of FFS was 6 (P<0.05). Lightness (L*) and yellowness (b*) of nanocomposite films generally increased with increasing pH levels. Transparency of nanocomposite films was affected to some extent by pHs. Homogeneity and smoothness of film surface were obtained for nanocomposite films with pH 6 as confirmed by SEM micrographs. Thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses indicated that thermal stability of nanocomposite films varied with different pH levels. In general, mechanical and water vapour barrier properties of nanocomposite films were improved when FFS having pH 6 was used. Thus, the pH of FFS directly affected the properties of nanocomposite gelatin films incorporated with hydrophilic nanoclay.