臭氧处理对采后黄瓜贮藏品质的影响

目的研究不同浓度臭氧处理对采后黄瓜贮藏品质的影响。方法分别用浓度为1、3和5μg/mL臭氧处理用微孔膜包装的黄瓜15 min,每隔1 d处理1次,于7℃冷库中贮藏,并通过测定黄瓜硬度、可溶性固形物、可滴定酸、维生素C、叶绿素、丙二醛、过氧化物酶活性等指标来确定处理黄瓜的合适臭氧浓度。结果与对照组相比,采用5μg/mL浓度的臭氧处理可保持黄瓜较好的硬度,减缓叶绿素、抗坏血酸、可滴定酸和可溶性固形物等营养成分的降低,有效抑制丙二醛的积累,抑制过氧化物酶的活性。结论臭氧处理可以保持黄瓜的生理生化指标,提高黄瓜的贮藏品质,其中5μg/mL的臭氧处理效果最好。     

Removal of residual pesticide, fenitrothion, in vegetables by using ozone microbubbles generated by different methods

The effects of ozone microbubbles (OMB) generated by different methods on removal of residual fenitrothion (FT) in three kinds of vegetables were examined. FT-infiltrated lettuce, cherry tomatoes and strawberries were immersed in solutions containing OMB generated by using a microbubble generator of a decompression-type or a gas-water circulating-type combined with an ozone generator at an initial OMB concentration of 2.0 ppm for 0, 5 or 10 min. Residual FT in each vegetable was removed more efficiently by the OMB treatments with the decompression type than with the gas-water circulation type, showing that the pesticide-removing effect of OMB varies with the method of OMB generation.     

臭氧处理对番茄果实贮藏品质和芳香物质的影响

目的研究不同浓度臭氧处理对番茄贮藏期转色、生理变化及香气成分的影响。方法以青番茄为实验材料,采用微孔膜包装,每隔3 d采用多功能果菜消毒机处理番茄1 h,使臭氧浓度达到2.07、6.20、10.34mg/m~3(以空气计),10℃恒温贮藏。用气相色谱-质谱联用仪测定其香气成分。结果通入10.34 mg/m~3臭氧气体的番茄果实贮藏效果最好,呼吸高峰延迟出现,呼吸强度降低,显著提高了番茄的贮藏保鲜效果。贮藏12 d时,与对照组相比,2.07、6.20、10.34 mg/m~3臭氧处理的芳香物质种类分别减少10.00%、15.00%、17.50%。结论臭氧处理能有效提高番茄的贮藏品质,并对番茄果实香气有抑制作用。     

防止贮存期柿口干提取液氧化褐变的研究

柿叶提取液加入不同浓度的D－Vc、蜂蜜、β－环糊精、植酸、明胶、壳聚糖等药剂，于37℃恒温贮存40天后取样分析，结果表明：各试验组药剂对防止柿叶提取液中维生素C和单宁的氧化褐变有显著的效果。     

Influence of thermal treatment and storage on astringency and quality of a spreadable product from persimmon fruit

The aim of this work was to develop osmodehydrated products from cubes of persimmon (var. Rojo Brillante), which could be spread as a jam but keeping the typical aroma, flavour and colour of fresh fruit. The application of a thermal treatment in the filling stage has been studied, with or without a later pasteurisation step at 90 °C for 20 min. These spreadable products were stored at room temperature or in refrigeration. The chemical composition, pH, a_w, colour, astringency, antioxidant capacity and the growth of yeast, moulds and aerobic mesophiles were analysed after the manufacture process and throughout the storage (approximately 3.5 months). Sensorial analyses were also performed after 24 h of being prepared and after 49 days of refrigeration. The product obtained without thermal treatment was the best since it maintained the characteristic persimmon colour better and showed higher antioxidant capacity. Furthermore, it was the best, according to the panel, not only for appearance but also for flavour.     

响应面法优化过氧化氢法脱除柿子色素工艺的研究

目的 研究过氧化氢添加量、脱色温度和脱色时间对柿子粉色素脱除效果的影响。方法 采用过氧化氢法对柿子粉的色素进行脱除,并运用响应面法进行工艺条件的优化。结果 在单因素试验的基础上,采用脱色率为评价指标,运用响应面法确定了过氧化氢脱除柿子粉中色素的最佳工艺为过氧化氢添加量为10%,脱色温度40℃,脱色时间52min,在此条件下脱色率为72.13%,多糖保留率为85.75%。结论 采用响应面法优化的柿子粉的色素脱除过氧化氢法工艺条件准确可靠,方便可行,具有参考价值。     

Evaluation the quality characteristics of wheat flour and shelf-life of fresh noodles as affected by ozone treatment

In this study, the effects of ozone treatment on the microorganism mortality in wheat flour and shelf-life of fresh noodles were investigated, as well as the physicochemical properties of wheat flour and textural qualities of cooked noodles. Results showed that the total plate count (TPC) can be largely reduced in wheat flour exposed to ozone gas for 30 min and 60 min. Whiteness of flour and noodle sheet, dough stability, and peak viscosity of wheat starch were all increased by ozone treatment. Free cysteine content in wheat flour was shown to decrease significantly (P < 0.05) as the treatment time increased and remarkable protein aggregates were observed in both reduced and non-reduced SDS–PAGE patterns. In addition, ozone treated noodles were generally higher in firmness, springiness, and chewiness, while lower in adhesiveness. Microbial growth and darkening rate of fresh noodles made from ozone treated flour were delayed significantly.     

Effects of ozone treatment on pesticide residues in food: a review

In agriculture, pesticide residues have always posed a major safety hazard to human health. With the development of agricultural production and improvements in science and technology, additional methods for degradation of pesticide residues have emerged. Amongst them, ozone treatment recently became a popular method owing to its outstanding technical advantages. This review is an in-depth analysis of the mechanisms by which ozone treatment degrades pesticide residues. The main mechanism involves direct oxidation by oxygen atoms, and indirect oxidation driven by hydroxyl radicals. The effects of ozone treatment on pesticide residues in food with respect to the ozone concentration, duration of ozone treatment, type of food, variety of pesticides, level of pesticide residues and environmental factors have been discussed. Furthermore, the impact of ozone treatment on the quality of food is highlighted. Low levels of ozone result in minor changes to the visual and sensory characteristics of food. In addition, this article discusses several restrictions surrounding the current application of ozone treatment for the degradation of pesticide residues. More specifically, the most crucial issue is the potential toxicity of ozonation byproducts generated by the process, which is also the current focus of research on ozone treatment for the degradation of pesticide residues. After weighing the advantages and disadvantages of ozone treatment, it is recommended as a method of degrading pesticide residues.     

臭氧处理对新收获小麦品质的影响

为了探讨臭氧处理应用于加速新收获小麦后熟的可行性,在室温、臭氧处理质量浓度为5mg/L、处理时间0.5~2.0h条件下分别处理新收获小麦,研究臭氧处理对新收获小麦基本成分、破损淀粉含量、湿面筋含量、面团流变学特性的影响。结果表明,与未处理组相比,臭氧处理对新收获小麦的粗蛋白含量无显著影响(P0.05),但对粗淀粉含量、破损淀粉含量、湿面筋含量、面团流变学特性有显著性影响(P0.05)。     

臭氧处理对果实采后生理和贮藏品质影响的研究进展

臭氧作为一种新的非热杀菌技术得到越来越广泛的应用。文章在分析影响臭氧贮藏保鲜效果的主要因素的基础上,重点综述臭氧处理对果实采后生理和贮藏品质影响取得的最新进展,为臭氧更好地应用于果实贮藏保鲜提供理论依据和参考。     

柿果浆低温喷雾干燥数值模拟与试验

利用计算机流体力学及算法建立喷雾干燥机结构模型及气体连续相、液滴离散相等数值计算模型,得到柿果浆低温喷雾干燥过程中气相流场、温度场、压力场和颗粒运动轨迹等信息,分析了进风温度和进料速率对喷雾干燥柿粉的水分含量、集粉率和喷雾干燥机出风温度的影响,并将模拟结果与实验结果进行对比。结果表明,水分含量和出风温度的模拟值与实验值接近,且变化规律相同。结合数值模拟和正交实验结果,确定柿果浆最佳低温喷雾干燥工艺参数组合为进风温度388 K、入口进风量0.05 m3/s、进料速率为4.5×10-3L/s,实验集粉率为78.14%。      

Tracking residual organochlorine pesticides (OCPs) in green,herbal, and black tea leaves and infusions of commercially available tea products marketed in Poland

The content of residual organochlorine pesticides (OCPs) was examined in green, herbal, and black tea leaves as well as in their infusions prepared from tea products marketed in the main supermarkets in Poland. It was found that the detected mean levels of organochlorine residues in tea leaves ranged from ?1 dry weight. Among hexachlorocyclohexane isomers, γ-HCH in green tea occurred in the highest concentrations. Among dichlorodiphenyltrichloroethane (DDT) metabolites the highest level of p,p′DDT (1.96 ng g^?1 dw) was in green tea samples. The transfer of OCPs from tea leaves to brew was investigated. The present study revealed that during the infusion process, a significant percentage of the residues, particularly pesticides with high water solubility, were transferred to the infusions. The obtained results show that the percentage transfer of each pesticides from tea to the tea infusions ranged from 6.74% (heptachlor) to 86.6% (endrin). The detected residues were below current MRLs for these pesticides.     

臭氧对杂柑类采后生理指标的影响

研究了在常温条件下臭氧处理对杂柑(天草、南香、诺瓦)采后衰老生理的影响。结果表明:适当的臭氧处理能有效的抑制杂柑SOD活性的降低和电导率的升高,从而延缓杂柑果实的衰老。根据正交实验结果,确定天草在13mg/L的臭氧、90%的湿度、2次/d处理方法的环境中常温保鲜效果较好;南香的常温最佳保鲜条件是13mg/L的臭氧、85%的湿度、3次/d的处理方法;诺瓦在16mg/L的臭氧、80%的湿度、2次/d的处理方法的条件下处理保鲜效果显著。     

不同臭氧处理时间对荔枝汁杀菌效果及品质的影响

研究了不同臭氧处理时间对荔枝汁杀菌效果(细菌总数、霉菌和酵母)的影响,同时评价不同处理时间对过氧化物酶(POD)、多酚氧化酶(PPO)、超氧化物歧化酶(SOD)、色差(△E)、总酸、Vc和还原糖等品质指标的影响。实验结果表明:臭氧处理能明显降低荔枝汁中细菌、霉菌和酵母的残留率,其残留率随处理时间的增大而显著降低;Vc含量、POD活性和PPO活性随处理时间延长而减小,特别是Vc的含量下降尤为明显;而SOD活性、总酸含量、色差随处理时间延长而增大,还原糖含量变化不大。     

广东省农贸市场农药残留风险清单研究

目的了解广东省蔬菜的安全风险状况,制定农药残留风险清单,以期给监管人员提供指向性建议,提高食品安全监管水平。方法于2018年8～11月在广东省21个地市的农贸市场针对性抽检蔬菜风险品种191批次,采用国家标准方法检测蔬菜中的9种农药残留的含量,根据GB 2763-2016《食品安全国家标准食品中农药最大残留限量》规定的限量值进行判定。结果广东省农贸市场蔬菜总体合格率为91.1%,有4种农药残留项目超标,风险因子主要为毒死蜱、克百威、水胺硫磷、甲氰菊酯。有机磷、拟除虫菊酯类、氨基甲酸酯类农药污染较为严重;叶菜类、鳞茎类、豆类、芸薹属类蔬菜均检出农药超标。结论构建农药残留风险清单,重点抽查风险品种并对其风险因子监测模式是可行的,可有效提高监管的针对性,若配合快检产品的使用,监管的靶向性更强。     

臭氧处理对花生粕蛋白结构性能的影响

以花生粕蛋白为研究对象,深入解析臭氧处理时间(0、2、5、10和20 min)对其结构特征的影响。结果表明：随臭氧处理时间的延长,花生粕蛋白中苯丙氨酸、甲硫氨酸和半胱氨酸比例逐渐下降;花生粕蛋白中巯基含量随臭氧处理时间延长而显著降低,其二硫键与羰基含量则正相反,随处理时间增加而呈上升趋势;与此相同的是,臭氧处理后的花生粕蛋白的变性温度和吸热焓明显升高,说明臭氧有助于提升花生粕蛋白的热稳定性,然而0~10 min臭氧处理则显著降低其表面疏水性;此外,圆二色光谱显示臭氧处理导致花生粕蛋白二级结构的变化,使蛋白质中α-螺旋、β-折叠以及β-转角结构逐渐向无规则卷曲结构转变;SDS-PAGE电泳证实大分子蛋白聚集体(>250 kDa)的生成,这可能是由于部分蛋白分子内的二硫键被臭氧氧化而发生交联和聚集行为而引起的。由此可见,臭氧处理可显著改变花生粕蛋白的结构特性,主要表现为时间依赖性。     

Chemical and toxicological alterations of zearalenone under ozone treatment

Our work mainly studied the elimination of zearalenone (ZEN) from corn flour by ozone treatment. We found four degradation products, after separation and identification by UPLC-ESI-QTOF-MS, named as Compound 1 (m/z 335.18), Compound 2 (m/z 351.19), Compound 3 (m/z 321.19) and Compound 4 (m/z 367.18). Then, one main transformation pathway was predicted on the basis of molecular weight and the reaction mechanism of ozone. We had also detected two of the degradation products by our modified UPLC-MS/MS method in real samples—contaminated corn flour. We screened the toxicity of the parent ZEN compound as well as the ozone induced decomposition products with BALB/c mice to evaluate the safety of our method in vivo. Therefore, aqueous ozone was demonstrated to effectively degrade ZEN and chemical structure alternations of ZEN after ozone treatment were predicted in both pure ZEN and real contaminated-corn flour samples. Considering the presence of the by-products formed, differences in the toxic effects on mice exposed to ZEN before and after the ozone treatment emphasise the significance of further study on the quality and toxicity of real food samples after ozone treatment.     

Effects of ozone on functional properties of proteins

The present study investigates whether the ozone treatment could be an alternative to improve some functional properties of proteins. Ozone treatment was applied on whey protein isolate and egg white proteins which have been extensively used in food products to improve textural, functional and sensory attributes. Ozone treatment of proteins was performed either in aqueous solutions or as gas ozonation of pure protein powders. Foam formation and foam stability of proteins were enhanced extensively. The solubility of proteins were reduced as influenced from the aqueous and gas ozonation medium. The reduction was more pronounced in egg white proteins. Ozone treatment affected emulsion activity of whey protein isolate negatively and reduced the emulsion stability.     

揉捻和干燥方法对柿叶茶品质的影响

研究了揉捻和不同干燥方法对安溪油柿叶茶品质的影响。结果表明:揉捻可增加柿叶茶的细胞破损率,从而使柿叶茶的水浸出物含量增加,有利于提高柿叶茶的可冲泡性。柿叶茶采用炒干能够得到较适宜的营养成分含量,而且经过炒干的柿叶茶色泽黄绿、香气浓厚、滋味鲜醇回甘、叶底绿匀,感官评分高。柿叶茶炒干时要注意控制火候和时间,而且在炒制过程中还要经常翻动。