Active packaging films and edible coatings based on polyphenol-rich propolis extract: A review

The development of active packaging films and edible coatings based on biopolymers and natural bioactive substances has received increasing attention in recent years. Propolis, also called bee glue, is a natural resin substance collected by worker-bees from the mucilage, gum, and resin of several plants. In food industry, propolis is commonly extracted in solvents to afford polyphenol-rich extract with potent antimicrobial and antioxidant activities. The prepared propolis extract can be mixed with biopolymers, plasticizers, emulsifiers, and reinforcing agents to develop active packaging films and edible coatings. The functionality of active packaging films and edible coatings is closely related to the type, harvesting method, geographic origin, extraction method and extraction conditions of propolis, the content and composition of polyphenolic compounds in the extract, and the presence of other bioactive substances. Active packaging films and edible coatings based on propolis extract can impact the physical, biochemical, and sensory properties of food (e.g., fruits, vegetables, meat, and fish) during storage. This review focuses on the recent advances of active packaging films and edible coatings based on polyphenol-rich propolis extract. The impact of polyphenol-rich propolis extract on the structural characterization, functionality, and potential food applications of the films and edible coatings is summarized.     

生育酚抑制油脂氧化机制研究进展

生育酚是天然脂溶性抗氧化剂维生素E的重要组成部分,广泛存在于各种食用油中。但在加热条件下,油脂中生育酚在参与延缓油脂氧化反应过程中自身会发生损耗、转化和迁移,其转化产物是否还具备抗氧化活性成为研究热点。针对中餐食用油以高温煎炸为主的使用习惯,研究生育酚在高温煎炸条件下的转化及抗氧化活性维持十分重要。结合油脂氧化机理,主要总结了油脂中生育酚的抗氧化机制,重点对加热条件下生育酚抑制油脂氧化机制相关研究进展进行综合分析,旨在为合理及正确使用脂溶性抗氧化剂维生素E、发挥其营养保健功效、维持油脂品质提供一定参考。     

外源镧对不同品种黄瓜镉积累及镉化学形态的影响

采用盆栽实验研究了土壤重金属Cd（20 mg/kg）污染下,外源镧（0、10、20 mg/L LaCl3）对‘燕白’和‘津优1号’2 个品种黄瓜（Cucumis satiuus L.）生长、丙二醛含量、抗氧化酶活性及果实中的总Cd含量和形态的影响。结果表明：La提高了2 个品种叶和根的抗氧化酶（过氧化氢酶、超氧化物歧化酶和过氧化物酶）的活性,增加了2 个品种的叶、茎、根、果实干质量及植株总干质量。La对‘津优1号’植株干物质量的影响大于‘燕白’。外源La使黄瓜叶和根抗氧化酶活性升高可能是植株对Cd的抗性增强、干质量增加的生理机制之一。La减少了2 个品种果实中总Cd含量和不同形态Cd含量,但随着La质量浓度的增加,2 个品种果实总Cd含量和残渣态Cd（FR）含量表现为先降后升的趋势。外源La使黄瓜叶、茎、根和果实中的Cd含量分别降低了6.0%～10.2%、8.9%～23.5%、4.0%～29.2%和32.0%～49.8%。喷La后,单株果实的Cd含量和Cd积累量、植株Cd全量均以‘津优1号’＞‘燕白’。     

常压低温等离子体对黄瓜表面大肠杆菌杀菌效果及品质的影响

采用常压低温等离子体(Atmospheric Pressure Low-Temperature Plasma,APLTP)对鲜切黄瓜表面进行杀菌处理,研究APLTP对鲜切黄瓜表面大肠杆菌的杀菌效果。在单因素的实验基础上,利用响应面分析方法建立大肠杆菌杀菌率的二次项数学模型,利用模型对处理电压、处理时间和处理极距及其相互作用进行分析,并在最佳工艺条件下处理鲜切黄瓜,研究其品质的变化。结果表明:APLTP能有效杀死鲜切黄瓜表面的大肠杆菌,各因子对杀菌率的影响大小依次是处理电压处理极距处理时间,最佳工艺条件为处理电压170 V,处理时间5 min,处理极距2.5 cm,此时杀菌率高达99.65%,与预测值99.60%接近,提高了鲜切黄瓜食用安全性。APLTP处理前后黄瓜的水分含量、可溶性固形物、pH值、色泽、相对电导率、丙二醛及Vc含量变化均不显著(P0.05),较好的保持了黄瓜的水分、糖度、酸度和颜色,同时维持了细胞膜的通透性及抗氧化能力。     

Proximate composition and nutritional profile of by‐products from green urchin and Atlantic sea cucumber processing plants

Proximate composition, amino acid and fatty acid profiles, and mineral and vitamin contents of by‐products from Atlantic sea cucumber (Cucumaria frondosa) and green urchin (Strongylocentrotus droebachiensis) processing plants were investigated. Results showed that sea cucumber viscera, urchin digestive tract (UDT) and non‐commercial grade gonads contained 4.5–14.4% total proteins and 1.9–4.6% lipids (wet weight basis). They were rich in essential amino acids with values of about 36% of total amino acids. Samples were also rich in polyunsaturated fatty acids (44% of total fatty acids) and showed high content in EPA (～17% of total fatty acids), but low DHA level (0.2%) was observed. In terms of vitamins content, UDT showed highest retinol and alpha‐tocopherol contents when compared to other marine samples. Results showed that by‐products from echinoderm processing plants contain various nutritious components with levels generally comparable even better than their edible counterparts, and efforts should be invested to valorise these biological wastes in a world context of rarefaction of nutritional marine resources.     

Suppression of internal browning and maintenance of antioxidants in beeswax plus salicylic acid coated pear fruit during different storage conditions

Postharvest application of edible waxes blended with antioxidants is an effective strategy to regulate postharvest quality and antioxidant losses in fruits. Effect of beeswax coatings (BW 1.0% and 2.0%) alone or enriched with salicylic acid (SA) on antioxidant properties of pear fruit was studied during 67 days of cold storage and 20 days of supermarket storage conditions respectively. Results showed that under both the storage conditions fruits coated with BW + SA maintained higher total phenolic content (TPC), antioxidant activity and ascorbic acid content (AsA) as compared to the control. Furthermore, combined coatings significantly reduced polyphenol oxidase (PPO) activities and inhibited internal browning (IB) in pears throughout cold and supermarket storage. Overall, the BW 2.0% + SA 2.0 mM exhibited the most competitive effect in terms of preserving the antioxidant properties and preventing internal browning in pears during storage.     

Cultivars, culture conditions, and harvest time influence phenolic and ascorbic acid contents and antioxidant capacity of strawberry (Fragaria x ananassa)

Strawberries are a good source of micronutrients, especially antioxidant phenolics. More information is needed to better exploit the health-promoting effect of such fruits. Several studies focused on the effects of genotype, cultural practices, and seasonal variation on the antioxidant potential of strawberries, but often yielding contradictory results and/or focusing on only 1 source of variability. In the present study, we showed that total phenolic compounds, ascorbic acid, and antioxidant capacity strongly differed between genotypes of strawberry. The precise results revealed the importance of genetic background for the antioxidant capacity and for the content of total phenolics (with up to 3.3-fold variations). Other parameters may also influence the antioxidant capacity in strawberry such as harvest time, culture conditions, and environmental factors. Moreover, in this study, the harvesting time (at the same ripening stage) appeared to be very important, more important than genotype. Variations of the antioxidant capacity of up to 4.1-folds were observed following the harvesting time of "Elsanta" cultivar. PRACTICAL APPLICATION: This article compares the antioxidant capacity and the content in ascorbic acid and phenolic compounds of strawberries of different varieties and of fruits harvested from April to December at the same ripening stage. The importance of strawberry antioxidant capacity resides in its benefits for human health.     

Antioxidant capacity, phenolic content and vitamin C in pulp, peel and seed from 24 exotic fruits from Colombia

Twenty-four exotic Colombian fruits were evaluated for antioxidant activity and total soluble phenolics (TP) (edible part, seed and peel) and ascorbic acid content (edible part). The antioxidant activities were evaluated by ABTS (free radical-scavenging capacity) and FRAP (ferric reducing antioxidant power) methods. The ABTS, FRAP, TP and ascorbic acid values in the edible part were 3.25 to 175 ??M Trolox equiv/g fresh weight (FW), 6.29 to 144 ??M Trolox equiv/g FW, 15.7 to 1018 mg gallic acid equiv/100 g FW, and 0.53 to 257 mg ascorbic acid/100 g FW respectively. There were positive correlations between antioxidant activity (assessed by both ABTS and FRAP) and TP and ascorbic acid with the FRAP and ABTS methods. The edible part of banana passion fruits (P. tarminiana and P. mollisima) exhibited the highest values of antioxidant activity and total phenolics, while the highest level of ascorbic acid was recorded in the edible part of guava apple and cashew. The seeds with the highest values of antioxidant activity and total phenols were cashew, algarrobo, arazá and coastal sapote, while the peel of coastal sapote and algarrobo had the highest values of antioxidant activity and total phenolics. To the best of our knowledge, this paper reports the first evaluation of pulp, seed and skin of Colombian tropical fruits with a view to their knowledge utilization for the development of novel functional food products.     

温室黄瓜中4 种常用农药的残留分析

以华南型黄瓜和华北型黄瓜为研究对象,研究在不同施药条件下,施药后不同间隔期果实内百菌清、多菌灵、代森锰锌、吡虫啉的残留量。结果表明：黄瓜果实中农残量随施药与采收间隔期的延长呈下降趋势;华南型黄瓜的农残量显著低于华北型黄瓜;生产中农民使用喷雾方法防治黄瓜叶部病害,黄瓜果实中的农药残留量一般情况下不会超过国家最大限量标准。     

品种和成熟度对油橄榄鲜果功效成分及抗氧化能力的影响

油橄榄鲜果被广泛用作加工药材或作为蔬菜食用,不同品种及成熟度对其药用和食用价值具有重要影响。 本实验研究了10 个具有代表性的油橄榄品种（白橄榄、豆果、鄂植、佛奥、卡林、科拉蒂、克罗莱卡、皮瓜尔、 云台和配多灵）及3 个成熟度（早、中、晚）对其功效成分（总酚、总类黄酮、总黄烷-3-醇、橄榄苦苷和羟基酪 醇）和抗氧化能力（铁离子还原能力、清除1,1-二苯基-2-苦基苯肼自由基、羟自由基和超氧阴离子自由基能力）的 影响,并通过相关性和主成分分析研究了油橄榄鲜果不同品种及成熟度与所分析指标之间的关联性。研究发现：不 同油橄榄品种及成熟度对其功效成分影响程度不同,并且品种对所分析指标的影响大于成熟度;随着成熟度的增 加,油橄榄鲜果提取物的抗氧化能力（除清除超氧阴离子自由基能力）呈现增强趋势。通过对不同品种及成熟度的 油橄榄鲜果功效成分和抗氧化能力进行分析,为油橄榄品种的选育、采收、加工和应用提供理论依据。     

两种药食同源植物总生物碱的提取及其抗氧化作用

通过考察两种药食同源植物总生物碱提取率及抗氧化作用,为两种植物作为天然抗氧化剂的应用提供一定理论依据。采用超声波破碎法提取两种植物(马齿苋、蒲公英)的总生物碱,考察乙醇浓度、料液比、提取溶剂pH值、超声时间、超声功率和超声温度对两种植物总生物碱提取率的影响,确定两种植物总生物碱适宜提取条件。在两种植物适宜的总生物碱提取条件下,考察两种植物总生物碱提取率及抗氧化作用。试验结果表明,两种植物总生物碱提取率相差不大,马齿苋总生物碱提取率为20.48%,蒲公英总生物碱提取率为20.19%;通过考察不同质量浓度两种植物总生物碱提取物的总抗氧化能力,对ABTS+·、DPPH·、超氧阴离子、羟基自由基的清除能力和总还原能力,发现这两种植物总生物碱提取物都具有良好的抗氧化活性,可作为潜在的天然抗氧化剂在食品中应用。     

‘金丝小枣’在生长与成熟过程中活性成分及抗氧化活性变化规律研究

本文以6个不同生长与成熟期（S1^S6）的‘金丝小枣’为研究对象,通过高效液相色谱测定分析了枣果中的维生素C、酚类物质、环核苷酸、三萜酸、α-生育酚和β-胡萝卜素,同时采用分光光度计法测定了其在不同生长与成熟期的总酚、总黄酮含量以及枣果抗氧化活性。研究结果表明:随着枣果的生长成熟:其总酚、总黄酮、α-生育酚和β-胡萝卜素以及FRAP值、清除DPPH·以及ABTS+·自由基能力均呈现下降趋势;儿茶素和表儿茶素是枣果在生长与成熟过程中主要酚类物质。三萜酸含量在枣果的S3^S4期时最高,而c AMP和c GMP则随着枣果的生长成熟逐渐积累。      

Seasonal variations in polyphenols and lipoic acid in fruits of tomato irrigated with sea water

BACKGROUND: Polyphenols and lipoic acid, due to their functions of antioxidant and free radical scavengers, are universally recognized as beneficial for preventing widespread human diseases, including cancer, and cardiovascular and cerebrovascular pathologies. In addition, they contribute to the determination of food taste and colour. These compounds were determined in tomato fruits (Solanum lycopersicum L., cv. Daniela) picked at red‐ripe stage during spring and autumn from tomato plants grown in rockwool slabs in a greenhouse in nutrient solutions with either groundwater or dilute sea water. RESULTS: Compared with groundwater, total phenolic acids, flavonoids and dihydrolipoic acid in tomato plants irrigated with sea water showed a decrease during spring and an increase during autumn. The interaction between sea water and season played a significant role in polyphenol and lipoic acid production. CONCLUSION: The consumption of polyphenols and lipoic acid is related to oxidative processes, which could be induced by natural physiological processes or more by environmental changes such as salinity or high irradiance. The lower presence of these antioxidants, observed in spring, may be a consequence of the more noxious levels of oxidative stress induced by the high salinity treatment when applied under a higher irradiance, typical conditions of spring in comparison to autumn. Copyright © 2009 Society of Chemical Industry     

Release property and antioxidant effectiveness of tocopherol-incorporated LDPE/PP blend films

Low-density polyethylene (LDPE)/polypropylene (PP) blend films in various blending ratios containing 3000?mg kg?1 of tocopherol were manufactured by an extrusion process. Tocopherol release properties were characterised and correlated with antioxidant effectiveness in retarding the oxidation of linoleic acid contacting the films at 40°C. The conditions without tocopherol (control) and with instant tocopherol addition corresponding to the amount included in the films were also prepared and compared with the film-contacting solutions. The effect of tocopherol inclusion and the blending ratio on their physical properties was also examined. A wide range of tocopherol diffusivity in 6.6?×?10?1?-4.6?×?10?1?m2?s?1 were obtained by blend films. As PP content increases, the diffusivity decreased sharply at the beginning and levelled off later. The slower release of tocopherol in LDPE/PP blend films corresponding to lower tocopherol diffusivity retained the higher tocopherol concentration in the linoleic acid system providing better antioxidant effectiveness of the extended induction period in oxidation. The tocopherol inclusion reduced tensile strength and transparency significantly in an affordable range with higher tensile strength given by a higher PP ratio. LDPE/PP blending can be a useful tool to modulate the release profile of tocopherol and thus the antioxidant effectiveness of the tocopherol-incorporated antioxidant packaging film.     

Synergism of phosphatidylcholine on the antioxidant properties of α‐tocopherol in corn oils under different relative humidity

The effects of phosphatidylcholine on the antioxidant properties of α‐tocopherol (84 ppm) were determined in stripped corn oil with various moisture contents at 60 °C. The degree of oxidation in the oils was determined by analysing headspace oxygen content and conjugated dienoic acids (CDA). Generally, phosphatidylcholine acted as an antioxidant in stripped corn oils, whereas it accelerated the rate of lipid oxidation in nonstripped corn oils. As the relative humidity and moisture content increased, the antioxidant properties of phosphatidylcholine increased significantly (P < 0.05). Strong synergistic antioxidant effects were observed in samples containing both phosphatidylcholine and α‐tocopherol compared to samples with only phosphatidylcholine or α‐tocopherol. Oils containing phosphatidylcholine or α‐tocopherol under different moisture contents had different oxidative stabilities.     

食用菌中Pb2+和Cd2+的含量测定及对其富集规律的研究

调查了大连市市售的9种鲜食食用菌中Cd2+和Pb2+的含量,并对其重金属污染状况和健康风险进行了评价。研究了Pb2+和Cd2+含量与食用菌菌丝体中富集量的相关性。利用积累函数的反函数推导出了食用菌生长环境中Pb2+和Cd2+的最大安全限值。结果表明,大连市市售鲜食杏鲍菇、真姬菇和滑菇水分含量在91.0%以上;市售的食用菌中Pb2+检出率是100%,平均含量为0.2819mg/kg;Cd2+在食用菌中未检出。低浓度的Pb2+和Cd2+能够促进食用菌菌丝体的生长,高浓度的Pb2+和Cd2+对食用菌生长产生抑制作用;随着Pb2+和Cd2+含量升高,累积速率逐渐变小。      

Comparative study of crude and refined kenaf (<Emphasis Type="Italic">Hibiscus cannabinus</Emphasis> L.) seed oil during accelerated storage

This study assessed the changes of antioxidant activity and bioactive compounds of crude and refined kenaf seed oil during accelerated storage at 65°C for 24 days. 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were used to determine their antioxidant activity. The changes of phenolic, tocopherol, and phytosterol contents during the storage were also studied. The phenolic content and antioxidant activity of refined oil were significantly lower than those of crude oil after the accelerated storage. There was a decrease of 72.5% tocopherol content and 31.1% phytosterol content in the crude oil and a decrease of 67% tocopherol content and 12.1% phytosterol content in the refined oil during the accelerated storage. There was no significant difference in tocopherol and phytosterol contents for crude and refined oils after the storage. The rate of degradation of tocopherol and phytosterol contents in refined oil was slower than that in crude oil during the storage.     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.     

豆类种子及其芽苗菜的营养品质、功能性成分及抗氧化性研究

为阐明萌发对黑大豆(Glycine max)、红小豆(Vigna angularis)和豌豆(Pisum sativum L)的影响,研究了其种子及萌发后形成芽苗菜的生长特性(总质量、可食部分鲜重、可食率、苗长、含水量)、营养品质(粗蛋白和可溶性糖含量)、功能性成分(总酚、总黄酮含量)和抗氧化性(DPPH自由基清除力、ABTS自由基清除力、FRAP亚铁还原力)。结果表明,3个豆类种子中,黑大豆的营养品质、酚类含量和抗氧化性显著高于红小豆和豌豆。3个豆类芽苗菜以豌豆苗的总质量(12.83 g/10株)、苗长(16.02 cm)和含水量(93.82%)最高;黑大豆芽苗菜的可食部分鲜重(5.87 g/10株)和可食率(71.03%)最高;豌豆苗的可溶性糖含量(0.75 mg/g)、总黄酮含量(7.09 mg/g DW)最高;黑大豆芽苗菜的总酚含量(4.28 mg/g DW)最高、ABTS自由基清除力(110.39μmol/g DW)和FRAP亚铁还原力(75.52 mmol/g DW)最强。萌发显著降低了3个豆类的可溶性糖含量,提高了粗蛋白含量;黑大豆萌发以后酚类含量和抗氧化性显著降低,而红小豆和豌豆萌发后显著提高了其酚类含量和抗氧化性。此外,酚类含量与抗氧化性之间存在着显著的正相关性。因此,黑大豆种子、红小豆芽苗菜和豌豆芽苗菜具有较高的营养价值,含有丰富的酚类物质和抗氧化性。     

不同状态下海参中的铝含量测定及安全分析

目的 建立微波消解-电感耦合等离子体质谱测定海参中铝含量的方法,并比较评价不同状态下海参中的铝含量.方法 选取不同地市的30个干海参样品和15个即食海参样品,经微波消解后,采用电感耦合等离子体质谱进行测定.结果 铝在0～2.0 mg/L质量浓度内的线性关系良好,相关系数为0.9998,该方法检出限为0.5 mg/kg,...