Development of cellulose acetate based antimicrobial food packaging materials for controlled release of lysozyme

Antimicrobial packaging materials were obtained by incorporation of lysozyme into cellulose acetate (CA) films. In order to achieve controlled release of lysozyme, the structure of the films was changed from highly asymmetric and porous to dense by modulating the composition of the initial casting solution. The highest release rate, soluble lysozyme activity and antimicrobial activity were obtained with the film prepared from 5% CA solution including 1.5% lysozyme. Increasing CA content in the casting solution decreased the porosity of the films, hence, reduced the release rate, maximum released lysozyme activities and the antimicrobial activities of the films. In contrast, immobilized lysozyme activities and the tensile strength of the films increased. The incorporation of lysozyme did not cause significant reductions in tensile strength and elongation at break values except in films prepared with 15% CA. This study showed the good potential of asymmetric CA films to achieve controlled release in antimicrobial packaging.     

A comparative study of caffeic acid and a novel caffeic acid conjugate SMND-309 on antioxidant properties in vitro

Caffeic acid (3,4-dihydroxycinnamic acid, CA) has been identified as an important source of natural antioxidants in various agricultural products. SMND-309, which is a degradation product of salvianolic acid B, is a novel conjugate of CA, but little information has been known about its antioxidant activities. In present study, we compared in vitro antioxidant activities of CA and SMND-309 using different assays such as DPPH radical scavenging assay, hydroxyl radical scavenging assay, superoxide radical scavenging assay, total antioxidant activity, reducing power, and lipid peroxidation assay. Butylated hydroxytoluene (BHT) and Vitamin C (Vc) were used as the standard antioxidants. At the concentration of 20 μg/ml, SMND-309 and CA exhibited 93.4% and 92.1% scavenging on DPPH radical, while BHT and Vc indicated an scavenging of 37.9% and 93.0% at the same concentration, respectively. Furthermore, SMND-309 is more effective on total antioxidant activity and hydroxyl radical scavenging than CA.     

不同抗氧化剂体外抗氧化活性及其对肉品氧化稳定性的影响

为明确GB 2760-2014《食品安全国家标准食品添加剂使用标准》中允许添加至热加工肉制品使用的不同抗氧化剂的体外抗氧化活性与其抑制肉制品蛋白质氧化和脂肪氧化能力之间的关系,分别测定8种抗氧化剂的体外抗氧化活性(1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由...     

Antioxidant migration resistance of SiOx layer in SiOx/PLA coated film

As novel materials for food contact packaging, inorganic silicon oxide (SiO_x) films are high barrier property materials that have been developed rapidly and have attracted the attention of many manufacturers. For the safe use of SiO_x films for food packaging it is vital to study the interaction between SiO_x layers and food contaminants, as well as the function of a SiO_x barrier layer in antioxidant migration resistance. In this study, we deposited a SiO_x layer on polylactic acid (PLA)-based films to prepare SiO_x/PLA coated films by plasma-enhanced chemical vapour deposition. Additionally, we compared PLA-based films and SiO_x/PLA coated films in terms of the migration of different antioxidants (e.g. t-butylhydroquinone [TBHQ], butylated hydroxyanisole [BHA], and butylated hydroxytoluene [BHT]) via specific migration experiments and then investigated the effects of a SiO_x layer on antioxidant migration under different conditions. The results indicate that antioxidant migration from SiO_x/PLA coated films is similar to that for PLA-based films: with increase of temperature, decrease of food simulant polarity, and increase of single-sided contact time, the antioxidant migration rate and amount in SiO_x/PLA coated films increase. The SiO_x barrier layer significantly reduced the amount of migration of antioxidants with small and similar molecular weights and similar physical and chemical properties, while the degree of migration blocking was not significantly different among the studied antioxidants. However, the migration was affected by temperature and food simulant. Depending on the food simulants considered, the migration amount in SiO_x/PLA coated films was reduced compared with that in PLA-based films by 42–46%, 44–47%, and 44–46% for TBHQ, BHA, and BHT, respectively.     

In vitro procedure to predict apparent antioxidant release from wholegrain foods measured using three different analytical methods

Several methods have been applied to the measurement of antioxidants in biological samples. Extraction methods have previously relied on chemical methods which are non‐physiological. This paper reports the use of an in vitro method with enzymatic and fermentation steps, designed to mimic digestion through the gastrointestinal tract, on release of antioxidants from a range of wholegrain foods. A total of 41 samples, (31 raw foods, 10 of which were also analysed after cooking) were analysed using the ferric reducing antioxidant capacity and Trolox equivalent antioxidant capacity methods. Six samples were also measured using the oxygen radical absorption capacity method. The three antioxidant assay methods gave different apparent antioxidant activity trends, and the range of values was dependent on the type of food. The effects of cooking were mainly observed in the early stages of the incubation procedure, suggesting that cooking may destroy soluble antioxidants but not those bound within the food matrix. For all samples, apparent antioxidant release increased during the incubation period, suggesting that antioxidants bound within the food matrix may be released and exert their effects in different regions of the gastrointestinal tract. Copyright © 2005 Society of Chemical Industry     

三种抗坏血酸脂肪酸酯对共轭亚油酸的抗氧化性研究

本实验以葵花籽油为原料制备共轭亚油酸,以L-抗坏血酸、D-异抗坏血酸、棕榈酸和月桂酸为原料合成L-抗坏血酸棕榈酸酯、L-抗坏血酸月桂酸酯和D-异抗坏血酸棕榈酸酯,并研究上述酯对于共轭亚油酸的抗氧化效果。结果表明,添加0.02%、0.04%和0.08%的上述酯对于CLA具有明显且相似的的抗氧化作用,它们可以作为商品CLA的良好、安全的抗氧化剂。     

THE INFLUENCE of HEAT TREATMENT ON the ACTIVITY of LIPO-AND HYDROPHILIC COMPONENTS of OAT GRAIN

Lipids in oat grains are protected against oxidation by various chemical compounds with antioxidant properties. Biologically active compounds such as tocopherols, L-ascorbic acid, thiol, phenolic amino acids and phenol comnpounds feature such properties. Phenolic compounds inhibit lipase activity, protect lipids against oxidation and, as a consequence, protect plant cells against the destructive activity of free radicals. the disadvantage of natural antioxidants is their low resistance to high temperatures since heating over 80C destroys their antioxidant properties. Operation such as drying, blanching, roasting or extrusion destroy the protective system of plant lipids.
The paper is an attempt to explain to what degree extrusion conditions influence activity of natural antioxidants. Oat flour possessing the largest amnount of lipids and biologicaly active compounds compared to other cereal flour was used in the model system. It has been found that oat phenolic compounds are a mixture of free phenolic acids, esters and phenolic acid glycosides as well as flavonols and polyphenols. It has been established that alcoholic extracts produced from oat groat and flour had strong antioxidant properties, whereas the extracts from extruded substances did not reveal such properties. During extrusion, about 50% degradation of phenolic compounds was observed. Phenolic compounds were the main group of organic compounds enabling enzyme activity and playing an antioxidant role.     

不同品种猕猴桃果实的品质及抗氧化活性

测定10 种猕猴桃VC、可溶性固形物、可滴定酸、总酚、蛋白质和氨基酸含量,并据此进行聚类分析,通过比较其清除DPPH自由基的能力,探究抗氧化活性与VC、总酚含量的相关性。结果表明：猕猴桃成熟果实含可溶性固形物含量12.27%～20.37%、可滴定酸含量0.85%～1.77%、VC含量54.86～159.08 mg/100 g、蛋白质含量0.86%～1.85%、总氨基酸含量10.74～17.94 mg/g、总酚含量63.71～152.46 mg/100 g、对DPPH自由基的清除率为13.75%～68.34%。6 种营养成分在不同猕猴桃品种之间具有一定差异性,其中翠香、红阳、金桃和华优的可溶性固形物、VC和总酚含量均较高,而黄金果和海沃德的VC、总酚含量较低,其他品种的营养成分指标基本处于中等水平,华优的VC含量（159.08 mg/100 g）、总酚含量（152.46 mg/100 g）及DPPH自由基清除率（68.34%）最高,是营养价值最高的品种之一。猕猴桃的抗氧化能力与其中的VC和总酚含量之间呈现较高相关性,表明猕猴桃的抗氧化作用与其中所含的VC和酚类物质关系密切。     

Development of Antioxidant Packaging Material by Applying Corn‐Zein to LLDPE Film in Combination with Phenolic Compounds

Abstract: Functional active packaging materials were successfully developed by incorporating antioxidant agents into corn‐zein‐laminated linear low‐density polyethylene (LLDPE) film. The minimum effective concentrations of the active compounds (for example, thymol, carvacrol, eugenol) were determined and these compounds were then laminated into LLDPE films to develop corn‐zein‐laminated films with antioxidant agents. The release rate of antioxidant agents in gas and liquid media were determined along with the mechanical and water barrier properties of the films containing these compounds. Tensile strength and percentage elongation at break were reduced in the corn‐zein‐laminated LLDPE films when compared to typical LLDPE film. Furthermore, the ability of the corn‐zein‐laminated films to repel moisture decreased by approximately 12.2%, but was improved by incorporating hydrophobic antioxidant compounds in the corn‐zein layer. Examination of release kinetics in the gas and liquid phases verified that antioxidants were effectively released from the films and inhibited oxidation during testing. Finally, the films were used for fresh ground beef packaging, and effectively inhibited lipid oxidation and had a positive effect on the color stability of beef patties during storage. These results indicate that the developed antioxidant films are a novel active packaging material that can be effectively implemented by the food industry to improve the quality and safety of foods. Practical Application: Zein protein, a by‐product of corn processing industry, was laminated into plastic films in combination with natural phenolic compounds to develop antioxidant packaging films. The films demonstrated their efficient release patterns of antioxidant compounds, which are suitable for packaging applications and food protection.     

Antioxidant activity of yoghurt peptides: Part 1-in vitro assays and evaluation in ω-3 enriched milk

The aim of the present study was to investigate important factors contributing to the high oxidative stability of fish-oil-enriched yoghurt, with particular emphasis on the possible antioxidative effects of peptides released during yoghurt fermentation. Yoghurt samples were stripped from sugars and lactic acid and subsequently fractionated by ultrafiltration using membranes with cut off sizes of 30 kDa, 10 kDa and 3 kDa. The fractions were tested for antioxidant activity by investigating the inhibition of oxidation in liposome model system, 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity, iron-chelating activity, and reducing power. The lower molecular weight fractions were found to be more effective antioxidants than higher molecular weight fractions. The lower molecular fractions were further tested as antioxidants in fish-oil-enriched milk. On the basis of peroxide value, volatiles, tocopherol and sensory characteristics, the lower molecular weight fractions 3–10 kDa and <3 kDa showed protection against oxidation of fish oil to the same extent as caseinophosphopeptides. The oxygen content of the yoghurt was also found to be lower than that of milk. Thus our findings suggests that the higher oxidative stability of yoghurt might be due to antioxidant peptides released during the fermentation of milk by lactic acid bacteria and/or by the lower oxygen content of yoghurt, which subsequently reduces the oxidative stress of fish oil incorporated in the yoghurt. The results show that antioxidant peptides may be used as an ingredient in foods enriched with fish oils to increase their oxidative stability.     

Release of active compounds from agar and agar–gelatin films with green tea extract

Active biodegradable films based on agar and agar–fish gelatin were developed by the incorporation of green tea aqueous extract to the film forming solution. The effect of the partial replacement of agar by fish skin gelatin as well as the addition of the green tea extract on the physical properties of the resultant films was evaluated. Special attention was given to the release of antioxidant and antimicrobial compounds from the agar film matrices with and without gelatin. Agar–gelatin films were less resistant and more deformable than agar films. The inclusion of green tea extract decreased tensile strength and elongation at break in both agar and agar–gelatin films. Water vapour permeability and water resistance was not affected either by the replacement of agar by gelatin or the addition of green tea extract, but the water solubility noticeably increased in the films containing green tea extract. The presence of gelatin in the agar–green tea matrix film hindered the release of total phenolic compounds, catechins and flavonols in water. As a consequence, the antioxidant power released by the films was lower in the case of films containing gelatin. However, the antimicrobial activity of the films was not affected by the presence of gelatin.     

Physical properties of whey protein coating solutions and films containing antioxidants

ABSTRACT:  Antioxidants (ascorbyl palmitate and α-tocopherol) were incorporated into 10% (w/w) whey protein isolate (WPI) coating solution containing 6.67% (w/w) glycerol (WPI:glycerol = 6:4). Before incorporation, the antioxidants were mixed using either powder blending (Process 1) or ethanol solvent-mixing (Process 2). After the antioxidant mixtures were incorporated into heat-denatured WPI solution, viscosity and turbidity of the WPI solutions were determined. The WPI solutions were dried on a flat surface to produce WPI films. The WPI films were examined to determine transparency and oxygen-barrier properties (permeability, diffusivity, and solubility). WPI solution containing antioxidants produced by Process 1 and Process 2 did not show any difference in viscosity and turbidity, but viscosity was greater for the WPI solution with rather than without antioxidants. WPI films produced by Process 2 were more transparent than the films produced by Process 1. Oxygen permeability of Process 1 film was lower than Process 2 film. However, both the diffusivity and solubility of oxygen were statistically the same in Process 1 and Process 2 films. Both control WPI films and antioxidant-containing WPI films had very low oxygen solubility, comparable to polyethylene terephthalate films. Permeability of antioxidant-incorporated films was not enhanced compared to control WPI films.     

Migration analysis,antioxidant, and mechanical characterization of polypropylene-based active food packaging films loaded with BHA,BHT, and TBHQ

Polypropylene (PP) based active composite films were prepared by adding butylated hydroxy anisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylated hydroquinone (TBHQ) antioxidants using the extrusion molding process. All concentrations of BHT, 2% to 3% BHA, and 3% TBHQ significantly increased the tensile strength (TS) of the composite films compared with control films. Increasing antioxidant concentration decreased TS values for BHT films, whereas an opposite trend was observed for BHA and TBHQ films. BHA at < 2%, BHT at > 2%, and TBHQ at all added concentrations significantly reduced elongation at break (E_b) of the composite films compared to control films. Water vapor permeability (WVP) of 1% BHT film was not significantly different from control. However, other antioxidants especially at increased concentrations significantly increased WVP values. TBHQ films with 300% to 662% increase had the highest WVP and BHT films with 5% to 81% increase had the lowest WVP among composite films. All three antioxidants had a negative effect on the transparency of the films; however the effect of BHA at higher concentrations was greater. The antioxidants did not change the color attributes of the films. Films containing all antioxidants showed 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity, which increased with increase in their concentration, especially for those containing 3 wt.% BHT and TBHQ. Overall, incorporating BHA and BHT into a PP matrix improved mechanical, barrier, antioxidant properties, and film appearance and consequently were proposed for the development of antioxidant active PP films. TBHQ film is not recommended for food packaging because of its weak mechanical properties (lower E_b and TS values, higher WVP, and greater migration).     

Antioxidants Release from Solvent-Cast PLA Film: Investigation of PLA Antioxidant-Active Packaging

The release study of natural antioxidants, i.e., ascorbyl palmitate and α-tocopherol, and synthetic phenolic antioxidants including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate, and tert-butylhydroquinone (TBHQ) from polylactic acid (PLA) film into food simulants were accomplished. PLA antioxidant films were placed in contact with 95, 50, and 10 % ethanol at 40 and 20 °C. Released antioxidants were regularly measured by high-performance liquid chromatography system for 60 days. Ascorbyl palmitate was completely degraded during film preparation and is not a suitable antioxidant for PLA antioxidant-active packaging. The diffusion coefficient (D) and partition coefficient (K) of antioxidants were calculated based on obtained data. Diffusion of the antioxidants from PLA to the simulants showed a Fick’s behavior with the diffusion coefficient (D) value between 10^?9 and 10^?11 cm² s^?1 with 0–100 % of release. Faster and higher release of antioxidants occurred at 40 °C according to Arrhenius law. At 40 °C, TBHQ in 95 % ethanol decomposed to 2-tert-butyl-1,4-benzoquinone and other quinone derivatives, and α-tocopherol in 50 % ethanol decomposed to some unknown neoformed compounds. Antioxidants molecular weight, Log P, simulant polarity, and temperature were the most influencing factors on antioxidants release rate from PLA films in contact with food simulants. The D and K coefficients of studied antioxidants from PLA in three food simulants and two temperatures can be used to create PLA antioxidant-active packaging to continually control the oxidation reactions in diverse foodstuffs to ensure higher food qualities. The PLA antioxidant-active packaging approach also permits to reduce the amounts of directly added antioxidants in foods to provide safer foods.     

Trout‐Skin Gelatin‐Based Edible Films Containing Phenolic Antioxidants: Effect on Physical Properties and Oxidative Stability of Cod‐Liver Oil Model Food

Abstract: Trout‐skin (Oncorhynchus mykiss) gelatin‐based films containing antioxidants (epigallocatechin gallate (EGCG), 50 and 250 ppm w/w) and green tea powder (1% and 20% w/w of gelatin) were tested for tensile strength, elastic modulus, and elongation, and oxygen and water vapor transmission rates, in vitro antioxidant activity using the DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) assay and effect on stabilizing cod‐liver oil held under mild thermal abuse conditions. Cod‐liver oil overlaid with films was stored at 40 °C for 20 d and analyzed for peroxide value (PV) and thiobarbituric acid reactive substances (TBARS). Antioxidant activity was retained in films containing green tea powder, but was reduced (P < 0.05) in EGCG films (20 d, 23 °C). Water vapor transmission rate of the films incorporated with antioxidants did not change significantly (P > 0.05), but the oxygen transmission rate for films with 50 ppm EGCG and 20% green tea powder was significant (P < 0.05). Other physical properties varied with antioxidant incorporation. The TBARS and PV of control oil increased from 0.05 ± 0.01 to 4.71 ± 0.30 g MDA/kg oil and from 3.6 ± 0.2 to 178.3 ± 24.5 millieq peroxides/kg oil, respectively, after 20 d. For cod‐liver oil covered with control or antioxidant‐containing films, TBARS remained below 0.37 g MDA/kg oil and PV below 7 millieq peroxides/kg oil. Incorporation of antioxidants to the films did not reduce oil oxidation (P > 0.05) at the levels tested and this was confirmed by activation energy calculations. The rate of oil oxidation was more dependent upon the inherent oxygen barrier property of the films than the presence of antioxidants. Practical Application: This research has the potential to enhance the utilization of fish skins, a valuable food processing by‐product, as edible films with natural antioxidants to extend the shelf life of foods. The film physical properties and barrier to oxygen and water are investigated.     

Antioxidant/prooxidant properties of model phenolic compounds: Part I. Studies on equimolar mixtures by chemiluminescence and cyclic voltammetry

The electrochemical behaviour and the antioxidant effectiveness of ascorbic acid (AA), caffeic acid (CA), quercetin (Q), catechin (Cat), hesperetin (H) and their equimolar binary mixtures were evaluated by means of cyclic voltammetry and luminol Co(II)–EDTA chemiluminescence, respectively, with a view to the prediction of a potential prooxidant or synergistic behaviour of mixtures of antioxidants. An important synergistic oxidation between Q and Cat was observed. The mixture CA/AA manifested the most prooxidant tendency among all the tested compounds and their mixtures. AA increased the antioxidant activity of Q and decreased that of Cat. Q and Cat regenerated CA, the prooxidant effect of the mixtures increasing with less e-delocalisation. Cat and CA have an antagonistic effect. H has the closest oxidation potential to CA and a slight increase of its antioxidant activity was registered when mixed with CA, which was not the case when it was combined with the other compounds or measured alone.     

Oxidative stability of fish oil supplemented with carnosic acid compared with synthetic antioxidants during long-term storage

The effects of carnosic acid (CA) of different concentrations (0.1, 0.2, and 0.3 mg/g) and synthetic antioxidants on oxidative stability in fish oil stored for 66 days at different temperatures (30 and 4 °C) were compared. The investigation focused on the increase in peroxide and conjugated diene values, as well as free fatty acid and thiobarbituric acid-reactive substances. The changes in trans fatty acid and aldehyde compound contents were investigated by Fourier transform infrared spectroscopy, while the changes in polyunsaturated fatty acid content were monitored by gas chromatography–mass spectrometry. The results show that the three CA concentrations were more effective in restraining fish oil oxidation, in which a dose–response relationship was observed. The antioxidant activity of CA was stronger than that of vitamin E, but still weaker than that of tertiary-butyl hydroquinone. Fish oil supplemented with 0.2 mg/g CA exhibited favourable antioxidant effects and is preferable for effectively avoiding oxidation.     

Microencapsulation of a Natural Antioxidant from Coffee—Chlorogenic Acid (3-Caffeoylquinic Acid)

Chlorogenic acids, the main polyphenolic group present in coffee, which include the caffeoylquinic acids, are recognized as antioxidants with growing interest in pharmacological, cosmetic, and food applications. However, they can be easily oxidized and they are also very unstable when exposed to high temperatures. Therefore, they can suffer transesterification reactions during storage or food processing, limiting their applications. Nevertheless, this situation can be overcome or minimized by microencapsulation. The purpose of the present study was to prepare by a spray-drying process sodium alginate and modified chitosan microparticles with chlorogenic acid (3-CQA), characterize them (morphological analysis), and evaluate the release profile of 3-CQA from the microparticles in in vitro studies. Furthermore, their antioxidant activity and moisture content were determined. The results address the success of chlorogenic acid microencapsulation, resulting in stable microparticles with controlled release properties and good antioxidant activity, suggesting increasing applications in food and pharmaceutical industry.     

玉米皮阿拉伯糖阿魏酸酯体外抗氧化活性的研究

本文采用稀盐酸水解玉米麸皮得到低聚糖阿魏酸酯（FOs）,经D301大孔树脂的除杂和聚酰胺柱层析的分离获得FOs中的F-Ara组分,在分析结构后,对该组分进行了体外清除DPPH和超氧阴离子自由基的能力测定和还原力测定。结果表明,与标准物阿魏酸（FA）、BHA和维生素C相比,F-Ara均表现出良好的体外清除自由基活性,其活性随浓度的增加而增大;在试验浓度为0.6 mmol/L时,与标准物阿魏酸和维生素C相比,F-Ara显示出最高的还原值,说明F-Ara具有较强的还原力。以上结果揭示F-Ara可成为一种能应用到食品、药品和化妆品的天然高效的抗氧化剂。     

Comparative effect of carnosic acid, BHT and α-tocopherol on the stability of squalene under heating and UV irradiation

Squalene is prone to auto-oxidation because it has a high content of unsaturated bonds. The effects of carnosic acid (CA) and two common antioxidants (butylated hydroxytoluene and α-tocopherol) on oxidative stability in squalene at different accelerated conditions (heating and UV irradiation) were compared. The investigation focused on the increase in peroxide and thiobarbituric acid-reactive substances. The changes in functional group contents were investigated by Fourier transform infrared spectroscopy, while the changes in squalene content and impurities situation were monitored by gas chromatography–mass spectrometry. The results show that CA was more effective in restraining squalene oxidation under heating, UV-A and UV-B irradiation. The antioxidant activity of CA was stronger than that of α-tocopherol and butylated hydroxytoluene. Squalene supplemented with 0.2 mg/g CA exhibited favorable antioxidant effects and is preferable for effectively avoiding oxidation.