Bioactive edible films for food applications: mechanisms of antimicrobial and antioxidant activity

Abstract

In order to improve the quality of food and to extend their shelf life, a new generation of active edible films is being especially intended after the incorporation of organic acids, enzymes, antimicrobial proteins, phenolic compounds, or other functional ingredients such as probiotics, flavors, vitamins and nutraceuticals. These active compounds have different mechanisms of action related to their structure, their concentration, the nature of micro-organism targeted, the process of encapsulation or incorporation in the biopolymer film-networks. The application of the active films by direct contact or indirect contact via the head space also affects the bioactivity of these compounds. This article critically reviews the published work on active edible-films and their applications for food preservation. The classes of active compounds and their action mechanisms are firstly discussed. Then, an extended overview on their effect on model food (simulants) or on real food during storage was also addressed. Edible films offer two main advantages over the direct incorporation of the antimicrobial or antioxidant agents into the bulk food: 1) to control the diffusion of active compounds at the surface of the food and 2) to reduce the amount of preservatives added in the food.     

Food technology of the antioxidant nutrients

The evidence that the antioxidant nutrients (vitamin C, vitamin E, and beta‐carotene) may play a much more important role in our health and well being is growing rapidly. The knowledge gained by the nutritionists and biochemists will ultimately require a technical transformation to achieve successful application in foods. The physical and chemical properties of these compounds require specialized forms and techniques that must be matched to the particular food and its method of production. These properties make the application of these nutrients in foods a challenge for the food scientist. This presentation covers the practical aspects of adding these nutrients to various foods and describes some examples of how these nutrients can be applied.     

Comfort Foods: An Exploratory Journey Into The Social and Emotional Significance of Food

This paper uses symbolic interactionist and structuralist perspectives to examine the social construction of some food objects as “comfort foods,” highlighting how cultural studies of food should take into account its social and physiological dimensions. This study's empirical findings are based upon the food items brought to class by 264 undergraduate students at a southeastern university in the United States. Comfort foods are classified into four categories: nostalgic foods, indulgence foods, convenience foods, and physical comfort foods. We describe how particular food objects come to be associated with the relief of distress and show how food objects are manipulated to modify or change emotional states or feelings. The practical implications of this work extend to understanding the role that mood plays in food selection and considering the use of comfort foods under certain circumstances, such as when individuals are experiencing illness.     

Uric acid photo-oxidation assay: in vitro comparison of sunscreening agents

We present a new method to evaluate the photo-oxidative activity of sunscreening agents based on the photodynamic oxidation of uric acid. Uric acid was selected as the oxidant probe for its high reactivity to singlet oxygen and oxygen radicals, high sensitivity of detection using electrochemical (EC) techniques, low light absorptivity and high photochemical stability in the UVA/B region of interest, and stability to autoxidation. The method is demonstrated by the photodynamic oxidation of uric acid on co-irradiation with Rose Bengal, a highly efficient photosensitizing dye for the production of singlet oxygen (1O2). Using this assay we found that the relative photodynamic oxidation rates of UVB-absorbing sunscreens in 80% methanol on irradiation with >290 nm light decreased in the order 2-ethylhexyl 4-dimethylaminobenzoate (DMABA-2EH) > 2-ethylhexyl 4-methoxycinnamate (MCA-2EH) and the experimental sunscreens, 1-(1,1-dimethylethyl)-3-octanoyl-4,4-dimethyl- 1,4,5,6,-tetrahydropyridine (ICI-319) and 1-(2-methylpropyl)-3-propionyl-4,4-dimethyl-1,4,5,6-tetrahydropyridine (ICI-855). The relative photodynamic oxidation rates of UVA-absorbing sunscreens decreased in the order 4-tert-butyl-4'-methoxydibenzoylmethane (BMDBM) and 4-(2-propyl)benzophenone (PB) > 2-hydroxy-4'-methoxy-benzophenone (HMB) and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB). We have confirmed the photodynamic activity of DMABA-2EH for the production of singlet oxygen (1O2) using electron paramagnetic resonance (EPR) spectroscopy and the reagent 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP). We failed to detect the photodynamic production of the oxyradicals, superoxide (O2.-) and hydroxyl radical (HO.) using N-tert-butyl-a-phenylnitrone (PBN) and 5,5-dimethyl-1-pyrrolidine-1-oxide (DMPO) as a result of photochemical interference caused by these spin-trapping reagents. The uric acid photo-oxidation assay was also used to compare the photodynamic reactivity of light-reflective, microfine oxides TiO2, ZnO and ZrO2 suspended in aqueous 80% methanol. All of the microfine oxides (uncoated) showed greater photodynamic reactivity in equimolar dispersion than did any of the organic UVA- and UVB-absorbing sunscreens in homogeneous solution. In this assay the photodynamic oxidation rates for the microfine oxides decreased in the order ZnO > TiO2 (anatase) > ZrO2 > TiO2 (rutile).     

Natural antimicrobial/antioxidant agents in meat and poultry products as well as fruits and vegetables: A review

Synthetic preservatives are widely used by the food industry to control the growth of spoilage and pathogenic microorganisms and to inhibit the process of lipid oxidation extending the shelf-life, quality and safety of food products. However, consumer's preference for natural food additives and concern regarding the safety of synthetic preservatives prompted the food industry to look for natural alternatives. Natural antimicrobials, including plant extracts and their essential oils, enzymes, peptides, bacteriocins, bacteriophages, and fermented ingredients have all been shown to have the potential for use as alternatives to chemical antimicrobials. Some spices, herbs and other plant extracts were also reported to be strong antioxidants. The antimicrobial/antioxidant activities of some plant extracts and/or their essential oils are mainly due to the presence of some major bioactive compounds, including phenolic acids, terpenes, aldehydes, and flavonoids. The proposed mechanisms of action of these natural preservatives are reported. An overview of the research done on the direct incorporation of natural preservatives agents into meat and poultry products as well as fruit and vegetables to extend their shelf-life is presented. The development of edible packaging materials containing natural preservatives is growing and their applications in selected food products are also presented in this review.     

生物发酵法制丁二酸生产工艺的研究与应用

丁二酸是一种重要的化工原料,广泛用于食品、医药和化工等行业,市场前景广阔。微生物发酵法生产丁二酸具有高效、环保、可持续利用的特点,是一种新型的绿色化工生产工艺。本文介绍了微生物发酵法制备丁二酸的生产工艺并对其应用前景进行了展望。     

埃塞俄比亚发酵食品中乳酸菌的分离鉴定

采用传统纯培养方法对采集自非洲埃塞俄比亚地区的蜂蜜酒,咖啡,面引子等4份发酵食品中的乳酸菌进行分离纯化,运用16S rDNA序列分析和系统发育进化关系研究方法进行种属鉴定。结果表明,经16S rRNA基因序列分析,共分离到55株乳酸菌,分属于3个属,11个种或亚种,包括乳杆菌属(Lactobacillus)51株,肠球菌属(Enterococcus)3株,链球菌属(Streptococcus)1株,其中Lactobacillus paracasei为埃塞俄比亚地区蜂蜜酒中的优势菌株,占该样品总分离株的75%,Lactobacillus pontis为该地区面引子中的优势菌种,占该样品总分离株的41%。     

高效液相色谱-质谱联用测定婴幼儿配方食品中叶酸的含量

建立了婴幼儿配方食品中叶酸含量的高效液相色谱-质谱联用测定方法。采用C18色谱柱(4.6mm×250mm,5μm)进行分离,以5 mmol/L乙酸铵(含0.1%甲酸)溶液-甲醇为流动相梯度洗脱,柱温25℃,流速1.0 mL/min,进样量20μL,柱后分流比为1∶3,质谱采用多离子反应监测(MRM)方式进行检测,正离子模式,定量离子为m/z442.0→295.2。叶酸在0.001~2.500μg/mL的范围内线性关系良好(r=0.9989),该方法相对标准偏差(RSD)为2.6%~6.0%,回收率为83.9%~104.0%,检出限(S/N=3)和定量限(S/N=10)分别为1.0 ng/mL、3.3 ng/mL。该方法操作简便、灵敏度高、重复性好,可用于婴幼儿配方食品中叶酸的测定。     

食品反式脂肪酸检测方法研究进展

反式脂肪酸是一种具有反式构型不饱和脂肪酸,来源较为广泛;最近流行病学调查研究表明,反式脂肪酸对人体健康有很大危害,因此,世界粮农组织和世界卫生组织提出食品中反式脂肪酸含量应低于4%,欧洲各国也限定食品中反式脂肪酸含量。该文介绍近年国外反式脂肪酸检测方法研究进展,为我国反式脂肪酸检测提供参考。     

Enhanced antioxidant capacity and antimicrobial activity of tannic acid by thermal processing

Thermally processed tannic acid (PTA) showed stronger antioxidant capacity and antimicrobial activity by Rancimat^® and disc diffusion tests than fresh tannic acid (FTA).     

The effect of storage on the antioxidant activity of reconstituted orange juice which had been pasteurized by high pressure or heat

The effect of storage on the antioxidant activity of pasteurized reconstituted orange juice was studied. Either heat or high pressure was used for pasteurization and total antioxidant activity and ascorbic acid loss were measured during storage at different temperatures (0, 5, 10, 15 °C). The total antioxidant activity of orange juice, calculated as the sum of the activities of different antioxidant compounds, decreased during storage. This was mainly because of loss of ascorbic acid. However, rates of degradation of ascorbic acid were lower for orange juice treated with high pressure and this led to a better retention of its antioxidant activity when compared with juice pasteurized in a conventional way.     

反式脂肪酸危害与控制

通过对食品中反式脂肪酸含量强制标示,向广大消费者指出反式脂肪酸对人体健康危害;同时对油脂加工业而言,这也意味着一场旨在减少食品中反式脂肪酸变革开始。     

p‐Coumaric acid in cereals: presence,antioxidant and antimicrobial effects

Coumaric acid is a hydroxy derivative of cinnamic acid and naturally occurs in three isomers (ortho‐, meta‐ and para‐); p‐coumaric acid is one of the most commonly occurring isomer in nature. p‐coumaric acid, classified as a phytochemical and nutraceutical, is found in various edible plants, such as carrots, tomatoes and cereals. p‐coumaric acid (4‐hydroxy‐cinnamic acid) occurs widely in the cell walls of graminaceous plants. It decreases low‐density lipoprotein (LDL) peroxidation, shows antioxidant and antimicrobial activities and plays an important role in human health. It is found in the endosperm of kernels at a limited level; however, the amount of p‐coumaric acid increases significantly in peripheral tissues. In terms of cereal types, it appears that pericarp fractions in barley, wheat, oat and corn are the fractions richest in p‐coumaric acid. It is both a good antioxidant and a good antimicrobial; therefore, it is natural alternative instead of synthetic additives, nowadays.     

Reproductive performance of dairy cows is influenced by prepartum feed restriction and dietary fatty acid source

The objective of this study was to determine the effects of feed restriction and source of dietary fatty acids during the close-up dry period on postcalving reproductive performance of dairy cattle. Thirty-four days before expected calving, pregnant Holstein cows (n = 72; parity 1 to 5) were randomly assigned to 1 of 6 treatments. Treatments were ad libitum (AL) or 24% feed restriction (FR) in combination with 1 of 3 oilseed supplements at 8% of diet dry matter: canola, linola, or flax to enrich the rations with oleic, linoleic, or linolenic fatty acids, respectively. After calving, cows were fed a common lactation diet that contained no oilseeds. Measurements of uterus, corpus luteum, and follicles were obtained by ultrasonography twice weekly from 7 ± 1 d after calving until the first ovulation. Cows (n = 66) were subjected to timed artificial insemination (TAI), and pregnancy was determined 32 d later. Feed-restricted cows had lower dry matter intake and lost more body weight prepartum. Energy balance (Mcal/d) was negative in FR cows prepartum but they had a less severe negative energy balance postpartum. The dietary source of fatty acid did not affect energy balance. Cows fed AL had a higher incidence of uterine infections (10/37 vs. 2/35) but tended to have fewer ovarian cysts (2/37 vs. 7/35) than FR cows. Mean (±SE) interval from calving to uterine involution did not differ among dietary treatments (26.8 ± 1.8 d). Interval from calving to first ovulation was longer in cows fed canola than in those fed either linola or flax (34.7 ± 3.1 vs. 23.7 ± 3.2 and 21.0 ± 3.1 d, respectively). A greater percentage of cows fed AL conceived to the first TAI (47.1 vs. 18.8) and tended to have fewer mean days open (157 ± 10.8 vs. 191 ± 10.1) than cows fed FR. In summary, FR cows had a lower incidence of uterine infections, but they were less fertile as reflected by a lower percent pregnancy to first TAI and increased days open. Cows fed diets enriched in linoleic or linolenic fatty acids had a lesser incidence of ovarian cysts and ovulated sooner with no effect on energy balance or fertility.     

Determination of phytic acid in feeds and faeces of pigs and poultry by capillary isotachophoresis

A method for phytic acid determination in the feeds and faeces of pigs and poultry has been developed on the basis of capillary isotachophoresis. Phytic acid was extracted by 0.95 M HCl and separated from interfering compounds by iron precipitation. Complete formation of ferric phytate required 7 mol FeCl₃ mol⁻¹ phytic acid. Residual Fe³⁺ was estimated colorimetrically by the tiron reagent, and ferric phytate was dissolved in 1.5 M NaOH at 9 mol NaOH mol⁻¹ Fe precipitated. Analyses were carried out using an electrolyte system with Cl⁻ as the leading anion, bis‐tris‐propane, and 2‐morpholinoethanesulphonic acid as the terminating anion. The recovery of phytic acid (added to hen faeces) using this procedure was 962 ± 24 g kg⁻¹. The limit of determination of phytic acid was 0.3 µmol ml⁻¹ extract. The amount of phytic acid in feeds ranged from 8.3 to 10.8 g kg⁻¹ on a dry matter basis. Phytic acid P represented 112 g kg⁻¹ total P in faeces of young pigs (40–60 kg) fed a feed with supplemental phytase (490 U kg⁻¹), 153 g kg⁻¹ total P in faeces of finishing pigs and 185 g kg⁻¹ total P in faeces of non‐lactating sows. Excreta of laying hens contained 23.7 g phytic acid kg⁻¹ dry matter (362 g kg⁻¹ total P). The isotachophoretic method is sufficiently simple and reproducible to be used for routine analyses of feeds and faeces. © 2000 Society of Chemical Industry     

Peanut antioxidants: Part 2. Quantitation of free and matrix-bound phytochemicals in five selected genotypes with diverse antioxidant capacity by high performance liquid chromatography (HPLC)

Five peanut (Arachis hypogaea L.) genotypes with diverse antioxidant capacity were quantitatively profiled for p-coumaric acid, salicylic acid, resveratrol, and daidzein. The co-eluting compounds, caffeic/vanillic acid and ferulic/sinapic acid, were quantified on caffeic acid equivalent and ferulic acid equivalent bases, respectively. The HPLC analysis established significant genotypic differences (P < 0.05) in free and total phytochemical composition and also demonstrated the importance of the bound (e.g., conjugated and matrix-embedded) fraction. Specifically, the study suggested that 77–93% of the p-coumaric acid, 44–53% of the ferulic/sinapic acid, 71–89% of the salicylic acid, 59–68% of the resveratrol, and 89–97% of the daidzein in raw peanut kernels were present in bound forms. D147-p8-6F and Sutherland were sister-lines (derived from the same F2 plant) that had high foliar disease tolerance, high antioxidant capacity, and similar phytochemical profiles, which was consistent with associations between phytoalexin production and genetically determined disease resistance made by previous researchers. Principal components analysis linked high antioxidant capacity with a combination of phytochemicals that were not directly correlated in bivariate analysis (e.g., resveratrol was negatively correlated with caffeic/vanillic and p-coumaric acid) and that were not delineated by genotype.     

The antioxidant capacity of polysaccharide from Laminaria japonica by citric acid extraction

An optimal citric acid extraction condition (pH 2.0; extraction temperature: 120 °C; extraction time: 3 h) was developed to obtain polysaccharide from Laminaria japonica. The yield of polysaccharide was 13.31 ± 0.08%, with IC₅₀ value of DPPH radical scavenging activity of 0.98 ± 0.01 mg mL^?1. The viscosity of polysaccharide extracted by citric acid (LJPA) was eight times lower than that of polysaccharide extracted by hot water (LJPW), which may be attributed to the low average molecular weight of LJPA (17.12 kDa). Gas chromatography analysis indicated that LJPA was composed of rhamnose, fucose, xylose, manose, glucose and galactose with relative molar percentages of 4.51%, 20.27%, 12.43%, 12.81%, 10.29% and 39.69% respectively. Furthermore, LJPA exhibited significantly higher antioxidant capacities including oxygen radical absorbance capacity (ORAC), ABTS radical scavenging activity and reducing power than LJPW. Citric acid extraction showed a positive influence on the polysaccharide degradation and antioxidant capacities of L. japonica.     

发酵食品有害氨(胺)类代谢物:形成机制和消除策略

影响我国传统发酵食品安全最为重要的因素是各种含氮化合物代谢生成的有害胺(氨)类物质,如氨基甲酸乙酯、亚硝胺类和生物胺类等.以往基于生物化学和分子生物学的研究,已经阐明了与这些有害胺(氨)类物质相关的代谢途径及调控途径.在此基础上,研究人员通过一系列的代谢工程操作试图消除这些有害胺(氨)类物质的积累,但实际效果有限.近年来的研究表明,有害胺(氨)类物质的积累,与食品发酵过程中微生物对氨基酸等有机氮源的选择性吸收密切相关.由于部分氨基酸的滞后吸收,导致最终氨基酸无法有效利用,甚至被代谢为有害胺(氨)类物质.微生物对氮源的利用受到氮代谢物阻遏(Nitrogen Catabolite Repression,NCR)效应的严谨调控.对于NCR效应这一全局调控机制的解析,将对理解微生物积累有害胺(氨)类物质的机理,并进行有效消除,奠定良好的基础.本文综述了发酵食品有害胺(氨)类物质积累和NCR效应的研究进展,在此基础上提出利用对NCR效应的理性调控消除有害胺(氨)类物质积累的系统策略.