烘烤处理对燕麦总多酚含量的影响

本文运用紫外-分光光度计法评价烘烤处理对燕麦总多酚含量变化的影响。通过单因素实验和响应面实验确定了烘烤处理对燕麦总多酚的最佳提取工艺为烤制时间25 min,烤制温度105℃,浸泡时间26 min。在此条件下燕麦总多酚的含量为1.73 mg/g,与未经处理得到的燕麦总多酚含量2.17 mg/g相比,总多酚含量并没有大程度的减少。结果表明烘烤工艺对总多酚含量保留量较高,为进一步热加工处理进行了铺垫。      

Effects of heat treatment on the quality of fresh-cut Chinese water chestnut

A heat treatment to inhibit browning and maintain the quality of fresh‐cut Chinese water chestnut was developed. Slices of Chinese water chestnut, cv. Guilin, were immersed in boiling water for 30 s, placed into film‐wrapped trays and then stored at 4 °C for up to 12 days. Changes in browning, eating quality and disease incidence were measured. The effect of heat treatment on the content of total phenolics and activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) was also evaluated. The heat treatment effectively prevented browning associated with PAL, PPO and POD activities and total phenolic content and delayed the decrease in eating quality, which is associated with reduced total soluble solids, titratable acidity and ascorbic acid, compared with fresh‐cut Chinese water chestnut. Inhibition of browning by heat treatment without microbial growth was achieved for 12 days of storage at 4 °C. These results showed that heat treatment effectively maintained the quality of fresh‐cut Chinese water chestnut.     

Effect of pH,heat, and light treatments on the antioxidant activity of sweet potato leaf polyphenols

In the present study, the antioxidant activity of sweet potato leaf polyphenols was measured, and the effect of different pH values (3.0, 5.0, 7.0, and 8.0), temperatures (55, 65, 80, and 100°C), and light treatments on sweet potato leaf-polyphenols was investigated. Results showed that the O₂^? scavenging activity of sweet potato leaf polyphenols from cultivar Jishu No. 04150 was 5.84 and 6.20 times of that of tea polyphenols and grape seed polyphenols, respectively, at the concentration of 20 μg/mL. The oxygen radical absorbance capacity was 1.28 and 1.27 times of that of tea polyphenols and grape seed polyphenols, respectively. Sweet potato leaf polyphenols dissolved in pH 5–7 solutions showed higher retention rates of antioxidant activity. Heat treatment at 50 and 65°C and light treatment had little effects on sweet potato leaf polyphenols. In conclusion, sweet potato leaf polyphenols possessed high antioxidant activity and processing stability, having the potential to be a new type of natural antioxidant.     

微波处理对全麦粉及全麦生鲜面中PPO 和微生物的抑制研究

试验选取全麦粉为原料,研究了2种不同方式的微波处理(2 000 W,20~80 s和700 W,50~120s)对面粉中微生物和多酚氧化酶(PPO)活性的抑制效果。并验证了2种处理方式对全麦生鲜面中微生物生长速率和褐变速率的延缓作用。结果表明,随微波处理时间的延长,全麦粉中微生物数量和PPO活性均显著下降(P0.05)。微波处理后的全麦粉所制得的生鲜面褐变速率和贮藏前期的菌落总数明显降低,2 000 W处理40 s组全麦生鲜面比700 W处理90 s组表现出更好的颜色贮藏稳定性。     

Effects of incubation and polyphenol oxidase enrichment on colour, fermentation index, procyanidins and astringency of unfermented and partly fermented cocoa beans

Incubation of unfermented and partly fermented cocoa beans in acetate buffer, pH 5.5, at 45 °C increased yellowness, total colour differences and fermentation index value of the cocoa bean powders and decreased cocoa procyanidins (monomers to pentamers), and their astringency. Fermentation index and (–)‐epicatechin content, equivalent to those of fully fermented beans, were reached by unfermented beans after 4–8‐h incubation, but not by partly fermented beans even after 16 h. During incubation of partly fermented cocoa beans enriched with polyphenol oxidase, yellowness and fermentation index value were increased, whilst (–)‐epicatechin was decreased. Tyrosinase had a less significant effect in yellow colour formation, but showed a significant reduction of (–)‐epicatechin and increase in fermentation index compared with crude cocoa polyphenol oxidase. However, both enzymes have similar effects on procyanidin degradation and astringent taste reduction. Incubation of cocoa beans for 16 h increased the cut test score of unfermented and partly fermented beans by 50 and 30%, respectively.     

UV-B辐射对烟草(Nicotiana tobacum)叶片总多酚含量和PPO活性的影响

采用盆栽试验,以烤烟品种K326为供试材料,选择空间范围不大的云南玉溪大营街和通海2个不同海拔高度的植烟区为试验点,并选择玉溪烟区种植烤烟海拔最高的通海县(1806.0米),作为同一种植地分别减弱0%、25%、50%和65%UV-B辐射强度条件的控制试验区,探讨了烤烟生长过程中PPO活性和总多酚含量与UV-B辐射强度的时空动态变化之间的关系。结果表明:由于受两地不同降雨日数及云层覆盖的影响,UV-B辐射强度并不随海拔高度的升高而升高;PPO活性对UV-B辐射强度变化非常敏感,过高或过低的UV-B辐射强度将降低PPO活性,其中过高的UV-B辐射强度影响更大;在一定的UV-B辐射强度范围内,降低强度可提高PPO活性;与PPO活性相反,高的UV-B辐射强度可提高烟叶总多酚含量,但在一定辐射强度范围内,对其变化趋势影响不大;过低的UV-B辐射强度不仅降低总多酚含量,而且影响整个生长过程中总多酚含量的变化。     

沙棘叶中总多酚和总黄酮的提取工艺

利用正交试验L9(34)和单因素相结合的方法,研究采用超声波辅助提取技术提取沙棘叶中总多酚和总黄酮的工艺。结果表明,沙棘叶中的总多酚和总黄酮在20kHz的超声波作用频率下极易溶出,优化后的工艺条件为以40%的乙醇为提取剂,在20kHz的超声波作用频率下室温萃取15min。在该条件下,沙棘叶总黄酮的提取率为5.034%,沙棘叶总多酚的提取率为10.712%。该方法具有简便、高效,省时等优点,可为工业化生产提供指导。     

Effect of ultrasonic treatment on enzyme activity and bioactives of strawberry puree

The aim of this study was to evaluate the impact of ultrasound (US) at different frequencies (20, 370, and 583 kHz) and power levels (35 and 48 W) on the residual activity (RA) of peroxidase (POD) and polyphenol oxidase (PPO) in strawberry puree. Total anthocyanin content (TAC), total phenolic content (TPC), ferric ion reducing antioxidant power (FRAP) and trolox equivalent antioxidant capacity (TEAC) were also assessed. Results were compared with untreated, thermally treated at 40 °C (control) and pasteurized (90 °C) strawberry puree. POD and PPO RA were significantly (P < 0.05) reduced, whilst there was a significant (P < 0.05) increase in TAC (5%–19%) in all US-treated samples in comparison with the untreated samples and the controls. US at 20 kHz (35 W) increased significantly (P < 0.05) TPC (9%) and FRAP (6%) in strawberry puree, whereas the effect of 583 kHz (48 W) on these parameters was insignificant (P > 0.05). Pasteurization inactivated POD and PPO, however, decreased dramatically TAC (14%), TPC (17%) and FRAP (9.5%) in strawberry puree. These findings suggest that US is a promising novel non-thermal food technology that can be tailored to improve the quality of strawberry puree by inactivating enzymes responsible for food deterioration whilst maintaining the content of bioactive compounds.     

果蔬中总多酚和维生素C测定方法优化的研究

目的建立一种简单、准确地测定果蔬中总多酚和维生素C含量的方法。方法采用Oasis HLB固相萃取柱富集待测物质,用纯水洗脱回收水溶性干扰物质,用甲醇洗脱回收多酚类物质,加热水洗脱液除去其中的维生素C,优化福林酚比色法,测定总多酚和维生素C的含量。结果该方法的线性方程为Y=0.0118X+0.0045,R2=0.9989,确定福林酚比色法的条件为:在760 nm处测定,福林酚试剂:水(1:1),7.5%的Na2CO3溶液,温度为20~30℃,静置60 min。通过采用福林酚比色法分别测定原料提取液(RE)和水洗脱液(WE)中还原性物质的含量,取其差值作为样品总多酚含量。同时,测定加热处理水洗脱液(HWE)中还原性物质的含量,取其与WE测定结果的差值作为样品维生素C的含量。结论此方法简便实用、条件易满足,分析结果可靠,可应用于果蔬总多酚和维生素C含量的测定。     

葡萄酒中多酚及多酚氧化酶研究现状与展望

葡萄酒富含多种营养与保健成分,具有预防心脑血管疾病、抗氧化、抗菌、抗癌、助眠等保健功效,葡萄酒中多酚类物质因具有极强的抗氧化、抗菌与预防心脑血管疾病等生理药理活性而倍受人们推崇,但多酚氧化酶会氧化破坏葡萄酒中的多酚,不仅会使葡萄酒变色变质变味,还会使其营养和保健价值明显降低。对葡萄酒中的多酚以及多酚氧化酶进行深入研究不仅有利于优质葡萄酒的研发与生产,还将为相关食品药品与果酒科学的研究提供借鉴。该文主要对目前国内外对葡萄酒中多酚及多酚氧化酶的种类、制备方法、酶活测定方法、酶活的影响因素等内容的研究现状进行了概述,并对有待加强的研发内容及其前景进行了展望。     

茅台酱香型酒糟中总黄酮及总多酚含量的测定

建立酱香型酒糟中总黄酮及总多酚含量测定方法。以槲皮素为对照品,采用紫外分光光度法测定酱香型酒糟中总黄酮含量;以没食子酸为对照品,用Folin-Ciocateu比色法测定酒糟中总多酚含量,并对其测定条件进行了优化。结果表明,Folin-Ciocalteu比色法最优的测定条件为：加入Folin-Ciocalteu试剂2.5 mL、10% Na2CO3溶液4 mL,在室温下显色80 min。槲皮素和没食子酸质量浓度分别在0.021 0～0.105 0 g/L(R2 = 0.997 6)和0.000 5～0.005 7 g/L(R2 = 0.999 7)范围内与吸光度值线性关系良好,平均回收率分别为99.12%、99.82%,相对标准偏差(RSD)分别为0.61%、0.33%;茅台酱香型酒糟中总黄酮及总多酚含量分别为20.40 mg/g和4.78 mg/g。此方法操作简单,稳定性以及重复性良好,结果准确可靠,适用于酱香型酒糟总黄酮和总多酚含量的测定。     

Effect of heat treatment and salt addition on the physicochemical properties and quality of fresh noodles

Heat treatment and salt addition on the physicochemical properties and quality of fresh noodles were investigated. The water activity was decreased, while the bound water content was increased after heat treatment, and this effect was dependent on the treated intensity and salt concentration, which extended the shelf life of noodles. The content of SDS-soluble protein was decreased after heat treatment, and this effect was dependent on the treated intensity. However, 3% salt concentration can reduce the aggregation of SDS-soluble protein. The paste viscosities were reduced, whereas the gelatinisation temperatures increased after heat treatment, and the variation was increased with increasing salt concentration. The hardness and chewiness of cooked noodles were increased after heat treatment, but adding salt reduced this effect. Results showed the quality of heat-treated noodles can be precisely controlled by the addition of salt, and the optimal treatment condition was 98 °C and 2% salt concentration.     

不同优株花椒甲醇提取物麻味素、总多酚、总黄酮含量测定及抗氧化能力研究

为了从17种不同品种的花椒中筛选出最佳的优良品种,本研究以17种不同丰产优株花椒果皮为原材料,测定了花椒中麻味素、总多酚和总黄酮含量及抗氧化能力,并进行相关性分析。结果表明在17种不同花椒优株椒皮中,花椒果皮中总多酚、总黄酮和麻味素含量最高的样品分别是来自绳池的M37、M1和来自陕县的S1,而M31样品中总黄酮和总多酚含量最低,M4样品中麻味素含量最低。不同花椒果皮提取物均具有很好的还原能力和DPPH自由基清除力,且总多酚和总黄酮均与还原能力和DPPH自由基清除力之间呈现良好的相关性。研究表明,从大田中优选出的17株花椒丰产优株中,花椒果皮的主要活性成分具有显著差异,来自渑池的M37、M1和来自陕县的S1、来自灵宝的L1等丰产优株树可以作为不同花椒良种进行培植。      

蓝靛果多酚冻干粉稳定性及其总抗氧化能力研究

对采自长白山的蓝靛果忍冬冻果经提取、纯化,并制成蓝靛果多酚冻干粉,研究p H、光照、温度、氧化剂H2O2、还原剂Na₂SO3、防腐剂苯甲酸钠和葡萄糖、蔗糖、D-果糖对蓝靛果多酚冻干粉稳定性的影响,并通过总抗氧化能力（Total Antioxidant Capacity,T-AOC）测试,进一步分析了蓝靛果多酚冻干粉在不同条件下的抗氧化活性。结果表明:蓝靛果多酚在p H为2和3、低温避光条件下保存效果较好,蓝靛果多酚耐还原能力比耐氧化能力强,防腐剂苯甲酸钠对蓝靛果多酚稳定性无显著影响（p>0.05）,糖的加入有助于多酚保存率的提高,使其稳定性增强;通过总抗氧化能力（T-AOC）测试发现,在p H为2、3时,蓝靛果多酚的总抗氧化能力明显高于其他受试p H范围（p<0.05）,温度、光照对蓝靛果多酚抗氧化活性的影响存在显著性差异（p<0.05）,添加氧化剂H2O2会降低多酚的抗氧化活性,添加不同质量浓度的糖类对蓝靛果多酚抗氧化活性的影响显著（p<0.05）。      

几种不同提取方法对燕麦总多酚含量的影响

本文运用紫外-分光光度计法评价几种不同的提取方法对燕麦总多酚含量的影响,通过单因素和正交实验得到传统溶剂法提取燕麦总多酚的最佳工艺条件。其中传统溶剂法提取燕麦总多酚的最佳工艺条件为:乙醇体积分数55%,料液比1∶50 g/m L,水浴温度55℃,浸提时间2 h,燕麦总多酚含量为0.99 mg/g;超声波处理提取燕麦总多酚的最佳工艺条件为:超声波功率500 W,超声时间30 min,温度55℃,燕麦总多酚含量为1.32 mg/g;微波处理提取燕麦总多酚的最佳工艺条件为:微波功率500 W,微波时间7.5 min,温度55℃,燕麦总多酚含量为1.80 mg/g;超声波-微波处理提取燕麦总多酚的最佳工艺条件为:超声波-微波功率500 W,超声波-微波协同处理时间2.5 min,温度55℃,燕麦总多酚含量为2.02 mg/g。其中超声波-微波协同处理提取燕麦总多酚用时最短,得到的含量最高,可以选取该工艺为后续的实验提供科学依据。      

Effect of thermal processing on oxide reductase inactivation and on colour fixing in erva‐mate (Ilex paraguariensis St. Hill) leaves

Leaves of erva‐mate (Ilex paraguariensis St. Hill) were heat treated with different combinations of time and temperature. Polyphenol oxidase (PPO) and peroxidase (POD) residual activities and colouring (L, a, b and ΔE) were studied after treatment for 3 weeks. The best results for enzyme inactivation after heat treatment were obtained with the leaves treated at 450 °C for 15 s and at 500 °C for 10 s, with reductions of 90.6% and 83.4% for PPO and 94.5% and 92.7% for POD. These groups also showed low levels of enzyme activity during the first few days of storage, and a few days later no enzyme activity was detected. The data on the colours, specially –a values (green colour), were in accordance with results for enzyme activity and helped in the research on the changes that occur in the leaves during storage. Data from this work can be suggested for the improvement of the current method of erva‐mate processing, which is still performed empirically.     

茶多酚对冷藏草鱼片保鲜效果的研究

为研究茶多酚对冷藏草鱼片的保鲜效果,将鲜活草鱼剖杀和清洗后,沥水3min,分别在0.25%、0.5%、1.0%、1.5%、2.0%的茶多酚溶液中浸泡5min,沥水3min,真空包装后于4℃保存,每5d以感官评分、细菌总数、pH、挥发性盐基氮(TVB-N)作为质量指标,测定草鱼在冷藏过程中的品质变化。结果表明:茶多酚处理能够明显抑制细菌生长繁殖,降低TVB-N,减缓感官品质的下降速度。结论:茶多酚对冷藏下的草鱼具有良好的抗菌和抗氧化的作用,能够明显的延缓草鱼的腐败变质。     

微波处理对鲜湿面片褐变及其特性的影响

该研究探讨了微波处理小麦粉对鲜湿面片褐变及其特性的影响。利用微波技术处理小麦粉,测定鲜湿面片的色泽、小麦粉多酚氧化酶（Polyphenol Oxidase,PPO）活性,并通过分析面片水分分布、游离多酚含量、流变学特性以及小麦粉中蛋白质二级结构、巯基和二硫键变化,从而研究微波处理对鲜湿面片褐变及其特性的影响。研究结果表明：随着微波时间和功率的增加,鲜湿面片的白度呈现上升的趋势,在低微波功率下色泽无显著性差异,在较高功率700 W,处理时间为100 s时白度会因糊化现象而下降;PPO活性下降了42.78%,游离多酚24 h内变化量与未处理组比较下降了54.78%;面片弛豫时间T22和T23呈现先上升后降低的趋势,在中等强度处理时达到最大值;游离巯基整体呈现下降趋势,二硫键含量增加,在700 W处理100 s时分别为1.29、4.38 μmol/g;蛋白质二级结构中α-螺旋含量显著性下降,无规则卷曲含量显著性增加;在鲜湿面片的流变学特性中,G′和G″均呈现先增大后减小的趋势,tanδ呈现先减小后增大的趋势。综上所述,在微波功率为700 W,处理时间为80 s效果最佳,该研究可为面制品行业提供一定理论基础。