包装对松仁油脂氧化酸败抑制的研究

目的研究包装方式对松仁贮藏过程中油脂氧化酸败的影响。方法分别将松仁进行普通包装、真空包装、充氮包装、脱氧剂包装,监测贮藏期间松仁品质指标的变化规律,研究不同包装方式对松仁油脂劣变的影响。结果充氮、脱氧剂和真空包装松仁的过氧化值和酸价均低于普通包装,其中脱氧剂包装的过氧化值和酸价比普通包装的低52%,38%,充氮包装比普通包装的低46%,33%,真空包装比普通包装的低31%,16%。结论提高包装的阻隔性能够有效抑制松仁油脂的氧化酸败,改善储藏品质,其中脱氧剂包装和充氮包装的保鲜效果明显优于真空包装和普通包装。     

聚乳酸/茶多酚抗氧化膜的制备及其性能研究

以聚乳酸（PLA）为基材,茶多酚（TP）为抗氧化剂,通过流延法制备了具抗氧化活性的可降解PLA/TP共混膜,并研究了茶多酚添加量对共混膜包装性能及抗氧化性能的影响。研究结果表明：茶多酚与聚乳酸基质间发生了相互作用,茶多酚在聚乳酸基质中具有较好的分散性。天然抗氧化物茶多酚的添加使共混膜的拉伸强度、断裂伸长率以及透光率降低,但显著提高了共混膜的热封强度、透湿系数、透氧系数、溶解度和自由基清除率。当茶多酚的质量分数为0.9%时,共混膜的热封强度为3.31 N/(15 mm),透湿系数和透氧系数分别是纯PLA膜的1.68倍和6倍,透光率为88.1%,自由基清除率为89.18%,是一种具有应用潜力的环境友好型食品活性包装材料。     

迷迭香与大豆分离蛋白涂膜对生鲜猪肉的护色及抗氧化效果

通过在大豆分离蛋白中掺杂不同质量浓度迷迭香对生鲜猪肉进行涂膜处理,比较了不同涂膜剂与迷迭香喷洒处理对高氧气调下猪肉颜色、正铁肌红蛋白含量、TBARS 值、蛋白质羰基和硬度值的影响。结果表明纯蛋白涂膜有效延缓了猪肉TBARS 值的形成,但无法抑制蛋白质羰基和正铁肌红蛋白的生成,而迷迭香与蛋白膜结合对猪肉表现出不同的抗氧化效果。sr250 无法抑制猪肉颜色的褐变及脂类蛋白质的氧化,sr500,sr1000和sr2000 对猪肉颜色、脂类、蛋白质等抗氧化效果均达到甚至超过了迷迭香直接喷洒处理的效果,总体而言,sr1000 的抗氧化活性要好于sr500 和sr2000。实验表明适当浓度迷迭香与大豆分离蛋白复合能显著增强两者对猪肉的抗氧化活性。     

不同含量脱氢乙酸钠改性PVA薄膜 延长蛋糕保质期的研究

研究了不同脱氢乙酸钠含量的P V A薄膜对蛋糕保质期的影响,以得出最适于蛋糕保鲜用改性包装薄膜。首先,用流延法制备出以不同质量分数脱氢乙酸钠改性的P V A改性薄膜,然后将待测蛋糕切成一定规格并分别装入不同的PVA薄膜包装袋中进行贮藏试验。且每隔3 d,对样品蛋糕进行感官评价,并检测其失重率、菌落总数、酸价、过氧化值等,以评价改性包装的抑菌及抗油脂氧化效果。结果表明,添加脱氢乙酸钠改性后的PVA薄膜的保鲜效果均优于未改性PVA薄膜的;综合各因素的影响结果,确定添加质量分数为2%脱氢乙酸钠的改性PVA薄膜对蛋糕的保鲜效果较好,其不仅能有效阻止蛋糕中水分的流失,且蛋糕的抗氧化性能最强。     

不同抗氧化剂对聚乙烯醇复合膜性能的影响

目的利用不同水溶性及脂溶性抗氧化剂对聚乙烯醇(PVA)进行改性,以期在改善复合膜综合性能的基础上,重点提升其抗氧化能力。方法以茶多酚、柠檬酸、BHT和维生素E为变量,甘油/聚乙烯醇为基底,研究不同水溶性及脂溶性抗氧化剂对复合膜形貌、力学性能、透光性、耐水性能及抗氧化能力的影响。结果加入适量的抗氧化剂后,薄膜各项性能均有所增强。其中,茶多酚/聚乙烯醇复合膜的力学性能最优,茶多酚(1.5%)/PVA复合膜的拉伸强度可达47.85 MPa,断裂伸长率为375.69%。该复合膜显著提高了紫外线的吸收率,同时73.93%的自由基清除率为研究薄膜中最高。结论采用茶多酚改性聚乙烯醇,不仅可提升复合膜的包装强度,增强其耐水性能,更能增强抗氧化能力,为食品保鲜提供了良好思路。     

电子束和γ射线对油料氧化及霉菌的影响

目的探讨电子束和γ射线等2种射线对油料脂肪氧化及霉菌含量的影响。方法以花生、芝麻、大豆为原料,采用1,3,5,7,9 kGy的辐照剂量对样品进行辐照处理,分析不同射线和不同剂量处理对原料含油率、酸价、过氧化值和霉菌总数的影响。结果辐照对油料含油率基本无影响;2种射线辐照均能有效地降低花生、芝麻和大豆的酸价,而且变化规律相似,在电子束辐照剂量为5 kGy下花生、芝麻和大豆的酸价最低,分别降低了54.29%,37.50%,37.33%。γ射线辐照对花生和芝麻的酸价的下降幅度大于电子束辐照,而大豆的情况则相反;2种射线辐照对花生过氧化值的影响不大,但γ射线辐照的过氧化值整体上略低于电子束辐照;2种射线辐照在一定程度上增加了芝麻的过氧化值;大豆的过氧化值随着2种射线辐照剂量的增加而降低,在1～5 kGy剂量下,γ射线辐照降低大豆的过氧化值的幅度整体低于电子束辐照。辐照能有效地杀灭油料中的霉菌,且辐照剂量越大其杀菌效果越好。相比而言,γ射线辐照对油料的霉菌杀灭效果好于电子束辐照。结论 2种射线在3 kGy辐照剂量下对油料质量无显著的负面影响,可作为油料防虫和防霉的适宜剂量。     

金属复合添加剂对低碳MgO-C砖抗氧化性能的影响

通过对脱碳层面积的比较,研究了低碳MgO-C砖中Al和Si复合添加剂及Al和Al-Mg合金复合添加荆在600℃、1000℃和1400℃时的抗氧化效果.结果表明,Al/Si复合添加剂可明显改善低碳MgO-C砖的抗氧化性能,且试样的抗氧化效果随着Al粉加入量的增大明显增强,可见Al粉比Si粉的抗氧化作用更有效.但是单独添加Al粉时,低碳MgO-C材料抗氧化效果最好.Al粉或Al-Mg合金粉单独使用时对材料的抗氧化作用要优于混合使用时的作用效果,而且Al-Mg合金抑制材料中C氧化的效果不如Al粉的作用明显.综合考虑认为,单一金属添加剂的抗氧化效果优于复合添加剂.     

迷迭香护手霜配方及性能探究

为了更好地将植物天然活性成分应用到护肤配方中,以增稠剂用量、乳化温度、迷迭香提取液浓度3个单因素为自变量,以涂抹感受的综合评分作为响应值,利用响应面优化实验对迷迭香提取物护手霜的工艺配方进行参数优化,并对所制备产品进行感官评价、耐热耐寒性及刺激性等指标检测。结果表明：最佳工艺条件为迷迭香提取物质量分数75%,增稠剂用量0.20 g,乳化温度80 ℃。此条件下制得的迷迭香护手霜色泽均匀,质地清爽水润,pH值为5.85,具有良好的耐寒耐热性和稳定性,无刺激性反应,受到人们喜爱,为迷迭香提取物在护肤行业的研究提供一定的理论参考。     

明胶-壳聚糖-迷迭香提取物复合膜对冷藏鲟鱼品质的影响

目的 制备明胶-壳聚糖-迷迭香提取物复合膜（G-C-RE）,并研究其对冷藏鲟鱼的保鲜效果。方法 通过测定菌落总数、pH值、挥发性盐基氮（TVB-N）含量、硫代巴比妥酸（TBARS）含量、感官评价等指标来探究复合膜对鲟鱼贮藏品质的影响。结果 鲟鱼经复合膜处理后感官评分得到提高,特别是在维持鲟鱼气味上表现出显著的效果。在贮藏第6 d时,复合膜处理后鲟鱼的TVB-N值和TBARS值分别比对照组低27.7%和62.5%（P<0.05）,使冷藏鲟鱼的货架期从6 d延长至8 d,并使鲟鱼的菌落总数在第10天时才达到国标限值。结论 明胶-壳聚糖-迷迭香提取物复合膜具有抑菌和抗氧化作用,可保持鲟鱼的良好品质,有望成为一种新型的食品活性包装材料。     

鲳鱼复合生物保鲜剂冰的配比优化及保鲜效果

在单一生物保鲜剂研究的基础上,采用两因素三水平正交试验的方法,将不同浓度的茶多酚和植酸进行复配制冰后分组处理新鲜鲳鱼。对鲳鱼品质变化表征特性指标(感官评价),微生物指标(菌落总数),理化指标(挥发性盐基氮含量(TVB-N)、2-硫代巴比妥酸含量(TBA)和K值)进行分析,确定了鲳鱼复合生物保鲜冰的优化配比浓度,并验证其保鲜效果。研究结果表明:用茶多酚0.5%(w/v),植酸0.15%(v/v)的复合保鲜冰使鲳鱼的感官指标、微生物指标、理化指标均优于自来水冰的对照组,在1℃冷藏条件下的货架期由11~12 d延长至21~23 d。     

Antioxidant Properties of Selected Plant Extracts and Application in Packaging as Antioxidant Cellulose‐Based Films for Vegetable Oil

Selected plant extracts including cinnamon, clove, ginger, green tea and thyme were investigated for their antioxidant activity by using both β‐carotene‐linoleate bleaching agar well diffusion and β‐carotene‐linoleate bleaching broth assays, and for radical scavenging activity against free radicals using a 2,2‐diphenyl‐1‐picrylhydrazyl assay. Undiluted plant extracts (except ginger oil) showed a yellow zone of β‐carotene ranging from 15.3 to 38.2 mm in diameter. At a concentration of 50 μL mL^‐1, thyme yielded the highest antioxidant activity (260%), followed by ginger (254%), cinnamon (108%), clove (106%) and green tea (101%), respectively. Conversely, at a plant extract concentration of 0.39 μL mL^‐1 solution in ethanol, green tea yielded the highest radical scavenging activity (94.3%), followed by clove (93.4%), cinnamon (91.1%), thyme (30.4%) and ginger (8.29%), respectively. The minimum oxidative bleaching inhibitory concentrations (MOBICs) of these plant extracts were determined using a β‐carotene‐linoleate bleaching broth dilution assay ranging from 0.195 to 50 μL mL^‐1. The MOBICs of plant extracts in a range of 0.195–1.56 μL mL^‐1 could reveal an ability to inhibit the oxidation of β‐carotene‐linoleate broth. Cellulose‐based film containing cinnamon, clove or green tea showed positive activity against β‐carotene‐linoleate oxidation and 2,2‐diphenyl‐1‐picrylhydrazyl radicals. Protective effects of plant extracts incorporated in cellulose‐based pouches in stabilizing soybean oil were tested by measuring their peroxide values and free fatty acid contents during accelerated storage. Green tea‐incorporated cellulose‐based pouches exhibited stronger antioxidant properties in soybean oil than do butylated hydroxyanisole‐incorporated cellulose‐based pouches. This study showed the potential use of plant extracts as antioxidants for food packaging application. Copyright © 2011 John Wiley & Sons, Ltd.     

Supercritical fluid extraction of natural antioxidants from rosemary: comparison with liquid solvent sonication

Supercritical fluid extraction (SFE) and liquid solvent sonication, in combination with two different sample treatments, were compared for the extraction of natural antioxidants from rosemary leaves. Dried, ground, and sieved rosemary leaves (20 mg) were subjected to SFE with CO(2) at 355 bar at 100 °C (CO(2) density 0.72 g/mL) for 20 min at a liquid flow rate of 4 mL/min. The analytes were concentrated on an ODS trap and subsequently eluted with acetone. Antioxidants in the SF and liquid solvent extract were analyzed by HPLC. Compounds of known antioxidant activity such as carnosol, carnosic acid, and methyl carnosate were identified by mass spectrometry of the HPLC fractions collected. Freezing and grinding the samples in liquid nitrogen resulted in decreased carnosic acid recoveries. Supercritical CO(2) extraction provided the highest recovery of carnosic acid from rosemary leaves (35.7 mg/g), the lowest relative standard deviation (4.4%), and the cleanest extract [Formula: see text] no cleanup prior to HPLC was required. Among the liquid solvents studies, only acetone provided comparable results (73% recovery relative to SC-CO(2) extraction); however, it required decoloration with active carbon prior to HPLC analysis.     

Alternative binary blends and their synergistic effect on stability of soybean biodiesel

The primary antioxidant tert-butylhydroquinone (TBHQ) and an alternative additive, named 1,4-bis(ethylamino)-9,10-anthraquinone, were mixed to yield a potent blend able to be used in the field of biodiesel preservation. Physicochemical parameters such as peroxide value, total acid number, density and induction period were used to evaluate the effectiveness of the combination in stabilising soybean biodiesel during the accelerate storage period of degradation. The induction period values were also used to calculate the occurrence of synergistic effect, and it was observed a high percentage of synergism for the combined additives. The results showed that the presence of target alternative additive also enables lower the concentration of the primary antioxidant (TBHQ) in the blend. The cost-effective comparison was evaluated, and it was verified that the final cost of biodiesel can also be lowered, since the amount of additives (in the blend) required to meet the biodiesel specifications was reduced between 70 and 88%.     

tert-Butylhydroquinone as a spectroscopic probe for the superoxide radical scavenging activity assay of biological samples

As a more convenient and less costly alternative to electron spin resonance (ESR) and nonspecific nitroblue tetrazolium (NBT) and cytochrome c assays of superoxide radical (SR, O(2)(?-)) detection, a novel probe, tert-butylhydroquinone (TBHQ), is introduced for SR nonenzymatically generated in the phenazine methosulfate-β-nicotinamide adenine dinucleotide (PMS-NADH) system. SR attacks both TBHQ and SR scavengers incubated in solution for 30 min where scavengers compete with TBHQ for the O(2)(?-) produced. TBHQ, but not its O(2)(?-) oxidation product, tert-butyl-1,4-benzoquinone (TBBQ), is responsive to the CUPRAC (cupric reducing antioxidant capacity) spectrophotometric assay. The CUPRAC absorbance of the ethyl acetate extract of the incubation solution arising from the reduction of Cu(II)-neocuproine reagent by the remaining TBHQ was higher in the presence of O(2)(?-) scavengers (due to less conversion to TBBQ), the difference being correlated to the SR scavenging activity (SRSA) of the analytes. With the use of this reaction, a kinetic approach was adopted to assess the SRSA of amino acids, vitamins, and plasma and thiol antioxidants. This assay, applicable to small-molecule antioxidants and tissue homogenates, proved to be efficient for cysteine, uric acid, and bilirubin, for which the widely used NBT test is nonresponsive. Thus, conventional problems of NBT assay arising from formazan insolubility and direct reduction of NBT by tested scavengers were overcome.     

Synthesis of biodegradable films based on cassava starch containing free and nanoencapsulated β‐carotene

β‐Carotene may represent an excellent natural antioxidant, and nanoscale encapsulation may contribute to development of a new technique for addition of antioxidants in active packaging. The objective of this work was to develop active biodegradable films with addition of free β‐carotene or β‐carotene–loaded lipid‐core nanocapsules and to evaluate the interaction with the polymeric matrix. The addition of free β‐carotene led to a decrease in the mechanical properties of films, result of their hydrophobic character and less interaction with the matrix. β‐Carotene nanocapsules caused the increase of colour intensity of films, elongation at rupture, and less light transmission, with the gradual increase according to increase in concentration. Films with β‐carotene nanocapsules presented greater protection of sunflower oil, with lower formation of oxidation products. The lower stability of free antioxidant led to behavior similar to control film, with less oxidation protection. The addition of nanocapsules can provide better interaction with the structure, since the encapsulated carotenoid exhibits solubility in aqueous medium and present better distribution, without altering the rapid biodegradability and thermal stability of films. The results show that encapsulated bioactive compounds can be used as hydrophobic natural antioxidants and added in active biodegradable packages for maintaining food safety and extending the shelf life.     

Characterization of antioxidant activity of extracts from Flos Lonicerae

Antioxidants are emerging as prophylactic and therapeutic agents for various diseases. However, little is known about the antioxidant property of the extract from Flos Lonicerae, a medically useful traditional Chinese medicine herb. Here the antioxidant capacity of water, methanolic and 70% ethanolic extracts prepared from Flos Lonicerae to scavenge DPPH radical and reduce Fe³⁺ to Fe²⁺ is evaluated. Chlorogenic acid, a major component of Flos Lonicerae, is identified and further purified from 70% ethanolic extract with HPLC and its antioxidant capacity is also characterized. The content of total phenolic compounds and chlorogenic acid in Flos Lonicerae is determined. The present results demonstrate that all Flos Lonicerae extracts examined here exhibit antioxidant activity and chlorogenic acid is a major contributor to this activity, which implicates that the Flos Lonicerae extract may serve as potential source of natural antioxidants for treatment of some diseases.     

Characterization of Antioxidant Activity of Extracts from Flos Lonicerae

Antioxidants are emerging as prophylactic and therapeutic agents for various diseases. However, little is known about the antioxidant property of the extract from Flos Lonicerae, a medically useful traditional Chinese medicine herb. Here the antioxidant capacity of water, methanolic and 70% ethanolic extracts prepared from Flos Lonicerae to scavenge DPPH radical and reduce Fe³⁺ to Fe²⁺ is evaluated. Chlorogenic acid, a major component of Flos Lonicerae, is identified and further purified from 70% ethanolic extract with HPLC and its antioxidant capacity is also characterized. The content of total phenolic compounds and chlorogenic acid in Flos Lonicerae is determined. The present results demonstrate that all Flos Lonicerae extracts examined here exhibit antioxidant activity and chlorogenic acid is a major contributor to this activity, which implicates that the Flos Lonicerae extract may serve as potential source of natural antioxidants for treatment of some diseases.     

茶多酚可降解复合膜在食品保鲜中的应用研究进展

目的 介绍茶多酚良好的抗氧化性、抑菌性,综述国内外将茶多酚与可降解成膜基材复合后应用于食品保鲜的研究进展,为后续研究提供基础。方法 通过对国内外研究现状和研究成果的综述,介绍茶多酚的保鲜机理及与可降解成膜基质复合后在食品保鲜（肉类、蔬菜类、水果类等）方面的具体应用,并分析茶多酚的加入对复合膜保鲜效果的影响。结论 从发展趋势来看,可降解食品保鲜材料必将拥有广阔的发展前景。茶多酚的添加虽使得可降解复合膜的保鲜效果大大增加,但国内外在茶多酚复合保鲜材料方面的研究形式相对较单一,多以复合膜或者膜液形式进行保鲜。利用微胶囊技术与茶多酚复合保鲜材料相结合制备保鲜剂,既能够更好地控制保鲜剂的使用量,又能避免直接与食品过多接触,是一个值得尝试的新思路。