Effects of various plasticizers and nanoclays on the mechanical properties of red algae film

To manufacture red algae (RA) film, we used various plasticizers such as glycerol, sorbitol, sucrose, fructose, and polypropylene glycol (PPG), and then determined the mechanical properties of the RA films. The tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) of the films containing various plasticizers ranged between 0.43 to 9.10 MPa, 10.93% to 47.17%, and 1.28 to 1.42 ng m/m2sPa, respectively. RA films containing fructose as a plasticizer had the best mechanical properties of all the films evaluated. Incorporation of nanoclay (Cloisite Na+ and 30B) improved the mechanical properties of the films. RA film with 3% Cloisite Na+ had a TS of 10.89, while RA film with 30B had a TS of 10.85 MPa; these films also had better E and WVP values than the other RA films evaluated. These results suggest that RA/nanoclay composite films are suitable for use as food packaging materials. PRACTICAL APPLICATION: Edible RE/nanoclay composite films prepared in the present investigation can be applied in food packaging.     

Preparation and mechanical properties of edible rapeseed protein films

Edible films were manufactured from rapeseed oil extraction residues. To prepare rapeseed protein (RP) films, various concentrations of plasticizers and emulsifiers were incorporated into the preparation of a film-forming solution. The optimal conditions for the preparation of the RP film were 2% sorbitol/0.5% sucrose as plasticizer and 1.5% polysorbate 20 as an emulsifier. In addition, RP blend films were prepared. Gelidium corneum or gelatin was added to improve the physical properties of the RP film, and the highest tensile strength value of the films was 53.45 MPa for the 3% RP/4% gelatin film. Our results suggest that the RP-gelatin blend film is suitable for applications in food packaging. PRACTICAL APPLICATION: Edible RP films prepared in the present investigation can be applied in food packaging.     

Physical properties of a composite film containing sunflower seed meal protein and its application in packaging smoked duck meat

Sunflower seed meal protein (SP) films were prepared using various plasticizers, cross-linking agents, Cloisite Na⁺ or red algae, and their physical properties, such as tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) were determined. The TS, E, and WVP of the SP film containing sucrose and fructose (2:1) as a plasticizer and cinnamaldehyde as a cross-linking agent were 3.05 MPa, 34.42%, and 2.25 × 10⁻⁹ g m/m² s Pa, respectively. The incorporation of Cloisite Na⁺ improved the physical properties of the SP film. The TS of the SP/Cloisite Na⁺ composite film containing 3% Cloisite Na⁺ increased by 2.19 MPa, and the WVP of the composite film decreased by 0.52 × 10⁻⁹ g m/m² s Pa compared to the SP film. The incorporation of red algae also improved the TS of the SP film. The TS of the SP composite film containing 1.2% red algae increased by 3.82 MPa compared to the SP film. In addition, an SP/red algae composite film containing grapefruit seed extract (GSE) was prepared and used in food packaging. After 12 days of storage, the population of Listeria monocytogenes inoculated on smoked duck meats packed with the SP/red algae composite film containing 1.2% GSE decreased by 1.31 log CFU/g compared to the control packaging. Therefore, these results suggest that SP composite films can be prepared by the addition of red algae to the SP film–forming solution and that the SP/red algae composite film containing GSE can be used as an antimicrobial food packaging material.     

添加单宁对明胶可食膜性质的影响

如何提高明胶膜的机械性能和阻隔性能,一直以来是可食膜研究领域的重要内容。本文以不同剂量(0 mg/g、10 mg/g、20 mg/g、30 mg/g和40 mg/g)单宁添加于明胶液并以浇注法成膜,然后对膜的理化性质进行分析。研究结果发现单宁有效提高了明胶膜的拉伸强度,但降低了其断裂伸长率;当单宁添加量为30 mg/g(明胶干基)时,其拉伸强度最大(22.10 MPa),断裂延伸率最小(40.12%)。与对照膜相比,单宁的添加降低了复合膜水溶性,水蒸气透过率和氧气透过率。在单宁含量添加范围内,水蒸气透过性最低为1.49×10-11 g/(Pa·s·m);水溶性最低为27.76%,氧气透过率最低为21.63 meg/kg。同时,DSC分析表明单宁提高了明胶膜的热稳定性。FT-IR图谱表明单宁与明胶之间发生了以氢键和疏水键为主的物理交联作用。所以,单宁-明胶复合膜在食品包装方面具有潜在的开发价值。     

Effects of plasticizers and nano-clay content on the physical properties of chicken feather protein composite films

To prepare chicken feather protein (CFP)/nano-clay composite films and to evaluate the effects of various plasticizers and nano-clay concentrations on the mechanical properties of the films, CFP composite films with various concentrations of Cloisite Na⁺ were prepared, and their physical properties such as tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) were investigated. Optimal CFP films were formed with 5 g of CFP, 0.5 g of glycerol, and 1.5 g of sorbitol in 100 mL of film-forming solution; the TS, E, and WVP of the film were 4.74 MPa, 10.08%, and 3.11 × 10⁻⁹ g m/m² s Pa, respectively. After the nano-clay was incorporated into the CFP film-forming solution, scanning electron microscopy and X-ray diffraction studies were conducted to examine the structural characteristics of the CFP/nano-clay composite films. The incorporation of nano-clay improved the physical properties of the CFP films. The TS of the CFP/nano-clay composite film containing 7% Cloisite Na⁺ increased by 1.21 MPa, and the WVP of the composite film decreased by 1.15 × 10⁻⁹ g m/m² s Pa compared to the CFP film. Therefore, these results suggest that CFP composite films can be prepared with improved mechanical property by the addition of nano-clay and used as a food packaging material in the food industry.     

Physical properties and antimicrobial activities of a persimmon peel/red algae composite film containing grapefruit seed extract

As a by-product of dried persimmon production, persimmon peel (PP) can be utilized as an edible film base material. In this study, PP/red algae (RA) composite films were prepared, and their physical properties were determined. Among the PP composite films, the 4% PP/1% RA composite film had the best physical properties (7.31 MPa, 8.16%, and 4.99 ng m/m²s Pa for tensile strength, elongation at break, and water vapor permeability, respectively). The optical property of the PP composite film was desirable because the color of the film had an intrinsic persimmon color. In addition, the 4% PP/1% RA composite film containing 1% grapefruit seed extract was prepared as an antimicrobial film. These results suggest that this PP composite film can be applied to food packaging.     

海藻酸钠对鱼皮明胶膜理化特性的影响

采用罗非鱼皮明胶与海藻酸钠混合制备可食性复合膜,研究海藻酸钠含量对复合膜理化性质的影响。结果显示：单一罗非鱼皮明胶具有良好的成膜能力,但是机械性能差,将海藻酸钠添加到明胶膜中得到的复合膜抗拉强度和断裂伸长率有明显改善,海藻酸钠添加量在40%时,抗拉强度达最大值6.6?MPa,相对于纯明胶膜（5.5?MPa）和纯海藻酸钠膜（4.6?MPa）分别增加20%和43%,断裂伸长率也在此时达到最大值120%,比纯明胶膜（64%）和纯海藻酸钠膜（88%）分别增加87.5%和26.7%。海藻酸钠水溶性和吸湿率分别高达100%和48.7%,经共混后复合膜的水溶性降低至55%以下,吸湿率介于25%～40%之间,有较大的改善。流变学特性和X射线衍射分析结果表明：明胶和海藻酸钠具有良好的相容性,二者共混可制得性质稳定的复合膜,海藻酸钠与明胶的复合膜液为非牛顿流体,黏度和增稠能力较单一明胶膜有所增加。     

鲢鱼皮明胶-海藻酸钠复合膜的制备与性能

鲢鱼皮明胶膜因具有安全性高和来源丰富等优点受到广泛关注。然而鲢鱼皮明胶膜的力学性能和阻隔性能 较差,若作为食品包装膜将会受到限制。为了改善鲢鱼皮明胶膜的性能,将海藻酸钠与鲢鱼皮明胶共混制成复合 膜。结果发现,制成的复合膜外观透亮,有阻隔紫外线和油脂的性质;当添加体积分数为20%的海藻酸钠时,复合 膜的水溶性和水蒸气透过率达到最小,抗拉强度达到最大。说明复合膜的阻隔性能和力学性能都优于鲢鱼皮明胶 膜。对膜的傅里叶变换红外光谱图和X射线衍射图进行分析,表明鲢鱼皮明胶和海藻酸钠存在较强的相互作用,这 可能是复合膜性能发生变化的主要原因。     

Using Liquid Smoke to Improve Mechanical and Water Resistance Properties of Gelatin Films

Improvement of mechanical and water barrier properties is critical for gelatin films when applied to edible food packaging. A liquid smoke (LS) obtained from hawthorn nucleus was used to improve the performance of gelatin film based on its abundant compounds. Through SPME‐GC‐MS analysis, 86 volatile and semi‐volatile chemical compounds was detected in LS, in which the total carbonyl compounds were 27.60%, with the main aldehyde as 2‐furaldehyde (9.83%). For gelatin films, an observable influence of LS on film transparency was observed in gelatin films, but not for its thickness and microstructure. Desirably, adding LS into gelatin solution increased the tensile strength of the films, with a better value of 16.38 MPa as 3 wt% LS added, compared with the control (10.30 MPa). Accordingly, film elongation decreased with a LS dependent manner. Furthermore, the water resistance properties of gelatin film were improved by the LS addition, which was supported by the results of water contact angle, water vapor permeability. Moreover, the addition of LS also led to a higher insolubility for gelatin films. Also, thermal stability of the LS treated gelatin films was slightly enhanced with the DSC analysis. According to the FTIR spectra and crosslinking degree detection results, all the above enhancing of gelatin film should be attributed to the crosslinking between carbonyl groups in LS and amide functionalities in gelatin based on nucleophilic reaction.     

Controlled release of thymol from zein based film

Active packaging materials, able to release antimicrobial compounds into foodstuffs, can be used in order to inhibit or slow down bacterial growth during storage. Zein-based mono and multilayer films were loaded with spelt bran and thymol (35% w/w) to obtain edible composite polymeric materials. Various composite systems were developed to control the release of thymol. In particular, the thickness of the layers and the biodegradable fibres amount were varied. Results highlight that thymol release rate decreased with the increase of the film thickness for both mono and multilayer films, without spelt bran addition. Conversely, a significant increase of thymol release rate with the increase of the bran concentration is recorded for both mono and multilayer films.Industrial relevanceIn recent years, food safety is an important area of concern to the food industry. This fact requires packaging to be an integral part of the preservation concept. Consequently additional antimicrobial activity from the packaging material can aid in shelf life extension. The present work is focused on the development of controlled release systems based on zein incorporated with an active compound, thymol and natural fibres. Release rate of thymol from the developed mono and multilayer films, as affected by layers thickness and fibres amount, was evaluated.     

Preparation of a barley bran protein–gelatin composite film containing grapefruit seed extract and its application in salmon packaging

The physical properties of a composite film prepared from barley bran protein and gelatin (BBG) were investigated. Tensile strength (TS) and elongation at break (E) values of the BBG film decreased as barley bran protein content increased. TS increased with increasing gelatin content, but E values decreased. The optimal conditions for the preparation of the BBG film were 3 g barley bran protein, 3 g gelatin, and 1 g sorbitol in 100 mL film-forming solution. In order to inhibit the growth of pathogenic bacteria, a BBG film containing grapefruit seed extract (GSE) was prepared. After 15 days of storage, populations of Escherichia coli O157:H7 and Listeria monocytogenes inoculated on salmon packaged with the BBG film containing GSE decreased by 0.53 and 0.50 log CFU/g, respectively, compared to the control. Also, packing salmon with the BBG film containing GSE decreased the peroxide value and thiobarbituric acid value by 23.0% and 23.4%, respectively.     

壳聚糖明胶可食用复合膜的制备与抗菌性能研究

以壳聚糖和明胶为复合膜骨架材料,通过加入0.3%(体积比)甘油增塑剂,制备具有显著抗菌性能的可食用复合膜。以较高的抗拉强度、较大的断裂伸长率、较低的水蒸气透过系数为主要性能指标,对成膜骨架材料壳聚糖和明胶的配比进行优化。研究结果表明,当壳聚糖浓度为1.5%、明胶浓度为1.25%时,以6∶4的体积比混合,制备获得机械性能良好(抗拉强度为13.24 MPa,断裂伸长率为112.45%),水蒸气透过系数较低(0.4032 mg·mm·kPa-1·h-1·m-2)的最优化复合膜。通过红外光谱、X射线衍射、扫描电镜等手段对复合膜进行表征。结果表明,与壳聚糖膜和明胶膜相比,复合膜的内部分子之间有较强的氢键和分子间作用力,膜内部致密且水蒸气不易通过,同时复合膜液对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌均具有显著的抑制效果。     

An approach for the enhancement of the mechanical properties and film coating efficiency of shellac by the formation of composite films based on shellac and gelatin

The purpose of this study was to enhance the mechanical properties and film coating efficiency of shellac by the formation of composite films with different concentrations of gelatin. The composite films were prepared by the casting method and their mechanical and physicochemical properties were investigated. The results demonstrated that the puncture strength and percentage elongation of the composite film increased from 3.61 to 15.58 MPa and from 3.80% to 32.47% as the gelatin concentration increased to 50% w/w, respectively, indicating the enhancement of the strength and flexibility of the shellac film. The efficiency of the composite film over two model substrates, i.e., hydrophilic and hydrophobic substrates, respectively, was also studied. The work of adhesion and spreading coefficient of the composite film increased from 66.42 to 83.53 mN/m and from −8.14 to −3.07 mN/m for the hydrophilic substrate, indicating the improvement of the coating efficiency whereas the hydrophobic substrate showed the opposite trend with the increase in gelatin concentration. Therefore, the formation of the composite film not only improved the mechanical properties of shellac but also enhanced the efficiency of film coating by the modification of different concentrations of hydrocolloid polymer to suit with the type of coating substrate. Hence the knowledge of composite film could make beneficial contributions to the various applications in film coating for the food and pharmaceutical industries.     

兔皮明胶/迷迭香酸复合膜在猪肉冷藏保鲜中的应用效果

制备含有不同质量浓度（0、0.3、0.5、0.8 g/L）迷迭香酸（rosmarinic acid,RosA）的兔皮明胶膜,采用明胶膜单独包装和以明胶膜作为内包、聚乙烯（polyethylene,PE）膜为外包两种方式对新鲜猪肉进行包装。结果表明：使用RosA明胶膜包装可有效抑制猪肉在冷藏过程中挥发性盐基氮含量、菌落总数和pH值的上升,并对脂肪氧化有一定抑制作用,且保鲜效果与实验选择范围内RosA的质量浓度呈正相关。0.8 g/L RosA明胶膜包装组与单纯PE包装组可分别使猪肉的货架期由4 d（对照组）延长至8 d和6 d,PE/0.8 g/L RosA明胶膜包装组则可将货架期延长至10 d。此外,通过测定色差、硬度等指标以及直观观察猪肉颜色,发现贮藏过程中PE/RosA明胶膜包装组较单独RosA明胶膜包装组可以更好地保持猪肉质构品质和色泽。因此,PE/RosA明胶膜可以作为一种有效的活性包装方式,用于肉类的冷藏保鲜。     

Genipin交联明胶/溶菌酶缓释抗菌膜材料的微结构与性能研究

针对亲水明胶膜材料对抗菌剂缓释能力较差的问题,采用生物交联剂(genipin)调节膜材料微结构,制备出新型控释明胶/溶菌酶复合膜材料。系统研究了复合膜材料的力学性能、水汽阻隔性能、膨胀性和热性质等物理性能,并用AFM研究了膜材料的表面微结构,探讨了其结构-性能之间的关系。结果表明:genipin交联显著改善复合膜材料的力学性能,TS值从9.72 MPa逐渐增加至18.80 MPa;复合膜材料的膨胀度(swelling)随genipin浓度增加急剧下降,从1316%降至~200%;genipin交联提升复合膜材料的热稳定性。复合膜材的表面粗糙度依赖于genipin浓度,在低浓度段(0~1.0%),膜材料呈现平整表面微结构;高浓度(2.0%)时,膜表面出现不规则的突起,变得粗糙。适度的genipin交联有助于形成有序的三维网络结构,改善复合膜材料的物理性能;高浓度的genipin过度交联明胶基质,形成团聚状聚集物,及弱化明胶分子间相互作用,进而弱化膜材料的水汽阻隔能力。     

Three phase partitioning for simultaneous extraction of oil,protein and polysaccharide from rice bran

Three phase partitioning (TPP) technique was used to extract oil, protein and polysaccharides simultaneously from rice bran. The fatty acid composition of rice bran oil (RBO) and structure of rice bran protein (RBP) and rice bran polysaccharides (RBPS) were analyzed. Under the optimal conditions of (NH₄)₂SO₄ concentration 28% (w/v), slurry to t-butanol ratio 1:1.1 (v/v), pH 5.10, extraction temperature 40 °C and extraction time 1 h, the highest extraction yields of RBO, RBP and RBPS were 17.28%, 6.81% and 2.09%, respectively. The fatty acid composition of RBO was analyzed by GC, the structure of RBP was analyzed by FTIR and SDS-PAGE, and the structure of RBPS was analyzed by FTIR. The results were similar to those obtained by other methods. Therefore, TPP can be used as an effective technology for simultaneous extraction of oil, protein and polysaccharide from rice bran.     

蛋清蛋白/苹果多酚提高多糖基可食性包装薄膜性能及在腰果贮藏保鲜中的应用

海藻酸钠（sodium alginate,SA）、κ-卡拉胶（κ-carrageenan,κ-C）具有天然无毒、成膜性好的特点,常被用于制备可食用多糖基包装膜。但多糖薄膜具有亲水性强、机械性能差、抗氧化活性低等缺陷。本实验以SA、κ-C为复合多糖成膜基质,以乳酸钙为交联剂,并添加蛋清蛋白粉（egg white powder,EWP）增强多糖薄膜综合包装性能,添加苹果多酚（apple polyphenol,AP）作为抗氧化剂赋予薄膜抗氧化功能。通过傅里叶变换红外光谱、X射线衍射、扫描电子显微镜、紫外吸收光谱等方法分析各组分基团间相互作用,并对腰果仁进行包装贮藏保鲜实验。结果表明：本研究制备的多糖基可食用包装薄膜具有较好的综合包装性能和突出的抗氧化性能。与SA/κ-C薄膜相比,Ca2＋的交联使可食性薄膜的机械性能、阻隔性能显著提升。在最优添加量下,添加EWP使薄膜断裂延伸率由7.99%提高至20.81%,水蒸气渗透率降低了28.84%,氧气渗透率降低了27.07%;加入AP后,可食性薄膜抗张强度由18.58 MPa提升到30.23 MPa,水蒸气渗透率降低了42.35%,氧气渗透率降低了34.13%,同时薄膜阻光性能显著提升。此外,AP/EWP/SA/κ-C可食性薄膜包装降低了腰果仁贮藏期间的水分活度、水分质量分数、过氧化值和酸价,能有效抑制腰果仁的氧化酸败。结论：研究可为多糖/蛋白质基可食性复合包装薄膜的制备及应用提供参考。     

改性纳米TiO2-大豆分离蛋白抑菌保鲜膜的制备及其性能

选取表面改性的纳米TiO2制备大豆分离蛋白（soy protein isolate,SPI）膜,以复合膜的抗拉强度、断裂伸长率、水蒸气透过率、透光性、透氧性、透二氧化碳性为评价指标,通过单因素试验和正交试验优化制膜最佳工艺。结果表明,复合膜的最佳成膜工艺条件为SPI添加量4.5?g/100?mL、改性TiO2添加量2.0?g/100?mL、甘油添加量1.5?g/100?mL,其接触角为115.3°。傅里叶变换红外光谱仪实验结果表明,改性纳米TiO2-SPI复合膜与纳米TiO2-SPI复合膜、普通SPI膜在4 000～600 cm－1波数范围内呈现出相似的红外光谱,且由扫描电子显微镜以及原子力显微镜扫描结果可以看出,与纳米TiO2-SPI复合膜及普通SPI膜相比,改性纳米TiO2-SPI复合膜表面更为致密平整,表面性能表现更佳,改性纳米TiO2-SPI复合膜的结构性质要优于纳米TiO2-SPI复合膜及普通SPI膜。当改性TiO2添加量为2?g/100?mL、365?nm波长紫外灯照射6?h时,复合膜对大肠杆菌和李斯特菌的抑菌性能最强,抑菌率达到91.14%和92.81%。改性纳米TiO2-SPI复合膜具有一定的机械性能和良好的抑菌性能,在食品包装应用方面具有巨大潜力。     

Effects of essential oil on the water binding capacity,physico-mechanical properties,antioxidant and antibacterial activity of gelatin films

Gelatin films were prepared from gelatin solutions (10% w/v) containing Zataria multiflora essential oil (ZMO, 2, 4, 6 and 8% w/w of gelatin). Scanning electron microscopy observations indicate that ZMO droplets were well dispersed in the film matrix. Water solubility, water swelling, water uptake, water vapor permeability, tensile strength, elongation at break and Young's modulus for gelatin films were 27 ± 0.8%, 391 ± 11%, 135 ± 5%, 0.22 ± 0.014 g mm/m² kPa h, 4.4 ± 0.4 MPa, 125 ± 7% and 8.8 ± 0.4 MPa, respectively. Incorporation of ZMO into gelatin films caused a significant decrease in swelling and water uptake and increase in solubility and water vapor permeability, a significant decrease in tensile strength, increase in elongation at break, decrease in Young's modulus of the films, dose-dependently. Gelatin/ZMO showed UV–visible light absorbance/transmission ranging from 280 to 480 nm with maximum absorbance at 420 nm. Gelatin films exhibited very low antioxidant activity while, gelatin/ZMO films exhibited excellent antioxidant properties. The gelatin/ZMO films also exhibited excellent antibacterial properties against both Gram-positive and Gram-negative bacteria. Our results suggested that the gelatin/ZMO films could be used as an active film due to its excellent antioxidant and antimicrobial properties for food packaging applications.     

Characterization of gelatin films prepared from under-utilized blue shark (Prionace glauca) skin

Gelatin film from blue shark (Prionace glauca) skin was investigated in order to utilize what is one of the most serious marine wastes in Japan. Film properties from shark skin such as tensile strength (TS), elongation at break (EAB) were evaluated. The TS of gelatin film from shark skin was affected by the protein concentration (1, 2 and 3%) of the film-forming solution (FFS). TS of the film from a 2% protein FFS was the highest. EAB and water vapor permeability (WVP) increased with increasing FFS protein concentration. WVP of shark skin gelatin was evidently low as compared to gelatin films from other fish. An increase in the FFS protein concentration decreased transparency at almost all wavelengths. Furthermore, opacity at 280 nm was characteristically high as compared to films from bony fish skin. The addition of glycerol improved flexibility and enhanced the UV barrier property at 280 nm. However, transparency at the visible range and WVP increased with increasing glycerol content.From the above, it was suggested that shark skin gelatin film technology can be applied to pharmaceutical products or rich-fat food due to its excellent water and UV barrier properties.