Changes in nutritional constituents, anthocyanins, and volatile compounds during the processing of black rice tea

The present study was undertaken to assess the changes in nutritional composition, anthocyanins, and volatile compounds during 3 successive processes (soaking, steaming, and roasting) for black rice tea production. Significant (p<0.05) decreases of cyanidin-3-glucoside and peonidin-3-glucosidetotal content were presented in black rice grains during soaking, steaming, and roasting. However, only steaming and roasting caused significant (p<0.05) decreases in the contents of total starch and crude fat, whereas accompanied with a stable level of total starch during all the processes. Furthermore, 94 of volatile compounds were identified in the raw and processed black rice. Nonanal, butylated hydroxytoluene, 1-hexanol, naphthalene, and 1-octen-3-ol were the main volatile compounds. These volative compounds extracted from raw black rice grain varied widely compared to the processed materials. The study indicated that processing could significantly affect the profiles of nutritional compositions, anthocyanins, and volatile compounds during the production of black rice tea.     

麸皮预处理对全麦面团及面包的影响

本实验分别采用微波、烘烤、常压蒸汽、高压蒸汽对小麦麸皮进行预处理,研究比较了不同预处理方法对全麦面团和面包品质的影响。结果表明：和未处理全麦粉相比,烘烤、常压蒸汽和高压蒸汽处理均使全麦粉的稳定时间提高,其中常压蒸汽效果最显著,提高了4.2 min;同时,这三种处理方式分别使全麦面包的比容增加了6.92%、9.34%、5.19%,硬度分别降低11.81%、21.79%、19.57%,弹性分别提高2.59%、3.06%、1.65%。推测原因是这三种处理方式均显著降低了麸皮中的还原型谷胱甘肽含量,使全麦面团的游离巯基显著减少,二硫键显著增加,其中常压蒸汽和高压蒸汽效果最显著,分别使还原型谷胱甘肽减少了66.77%、69.30%,使游离巯基减少了40.43%、42.77%,使二硫键增加了51.35%、38.63%。综上,采用烘烤、常压蒸汽、高压蒸汽对麸皮预处理,可以通过降低还原型谷胱甘肽含量、提高二硫键含量来提高面团的稳定性,进而改善面包品质,且常压蒸汽处理的改善效果最好。     

Changes in phytochemical compositions,antioxidant and α-glucosidase inhibitory activities during the processing of tartary buckwheat tea

This study focused on the evaluation of changes in phytochemical compositions, antioxidant and α-glucosidase inhibitory activities during the processing of tartary buckwheat tea. Soak-treating tartary buckwheat significantly decreased the contents of total starch and rutin, whereas significantly increased the contents of quercetin, kaempferol, total flavonoid, and total phenolic compounds. In steam-treating soaked tartary buckwheat for 40–60 min, the contents of total starch, protein, crude fat, isoquercitrin, quercetin, kaempferol, total flavonoid and total phenolic compounds significantly decreased, whereas the content of rutin significantly increased. The reaction of rutin degrading might be catalyzed in soaking processing, and a catalytic reverse shift reaction of rutin-synthesizing might take place in steaming processing. The process of drying and roasting significantly decreased the contents of total starch, rutin, total flavonoid, and total phenolic compounds. The total phenolic content of collected tartary buckwheat materials positively correlated with the antioxidant and α-glucosidase inhibition activities.     

高花青素柏塘紫芽茶适制性的研究

目的 比较柏塘紫芽茶加工成蒸青绿茶、炒青绿茶和红茶的品质,研究柏塘紫芽茶的适制性。方法 将柏塘紫芽茶鲜叶加工成蒸青绿茶、炒青绿茶和红茶,采用国家标准方法测定其理化指标,并进行感官审评。使用GC-MS对绿茶以及红茶加工过程中的香气物质的变化规律进行分析。结果 柏塘紫芽绿茶中茶多酚的含量和酚氨比显著高于柏塘紫芽红茶,其中蒸青绿茶稍高于炒青绿茶。但红茶的加工很好地降低了柏塘紫芽茶由于高花青素含量导致的苦涩味。感官审评中,柏塘紫芽蒸青绿茶最优,红茶次之。对香气物质的检测发现,柏塘紫芽绿茶的加工普遍提升了香叶醇、芳樟醇和橙花醇等主要香气物质的含量,降低了影响口感和气味的酸类、醛类、酮类和烃类等物质的含量,对绿茶的香气和口感的形成十分重要。在红茶加工过程中,具有浓郁花果香的醇类、酯类和醛类的香气物质基本随着加工的深入总含量逐渐升高,具有青臭气的酮类、烃类和酸类的挥发性物质总量逐渐降低。醇类、酯类和醛类的香气物质在红茶的干燥过程中均有一定程度的损失。结论 柏塘紫芽蒸青绿茶、炒青绿茶和红茶均具有各自的鲜明特色,但蒸青绿茶和红茶的品质较佳,可根据不同喜好的消费群体进行推广和功能茶饮的研发,为柏塘紫芽茶的大面积推广提供理论基础。     

麦麸品种与提取方式对阿拉伯木聚糖结构及抗氧化性的影响

目的：利用不同方式提取不同品种小麦麸皮中的阿拉伯木聚糖（arabinoxylan,AX）,对提取的AX进行结构表征并比较其抗氧化性。方法：分别利用碱提、超声辅助木聚糖酶提和超声辅助纤维素酶提法从不同品种小麦麸皮（‘百农207’‘百旱207’‘冠麦1号’‘华育198’和‘华育166’）中提取AX,测定其化学组成,对比其分子质量、分子结构、热稳定性及抗氧化性能。结果：3?种提取方式中,碱提法得率较高,且总糖质量分数较高;酶提法则能更大程度地保留多酚,这可能是酶提AX抗氧化性较好的原因,但在一定程度上降低了AX的分子质量,且酶提AX单糖组分比例与碱提AX差异较大,糖苷键连接方式也更复杂;两种酶提法相比,超声辅助木聚糖酶提AX得率和总糖质量分数更高,但超声辅助纤维素酶提AX多酚质量分数更高,且二者单糖比例及糖苷键连接方式也不同;此外,不同品种麸皮AX的分子质量、单糖比例、糖苷键连接方式及比例不同。结论：碱提、超声辅助木聚糖酶提和超声辅助纤维素酶提3种方法从小麦麸皮中提取得到的AX结构及活性存在明显差异,酶提法相对碱提法AX得率和分子质量较低,但多酚含量较高、抗氧化性能较好;超声辅助木聚糖酶提较...     

麸皮稳定化处理方式对全麦粉品质的影响

研究了微波、常压蒸汽和挤压三种麸皮稳定化处理方式对全麦粉理化性质、加工品质、贮藏稳定性及抗氧化活性的影响。结果表明:挤压处理降低了全麦粉湿面筋含量;挤压和蒸汽处理显著提高了全麦粉的降落数值（P<0.05）,微波处理对降落数值没有显著性差异。蒸汽处理后,全麦面团的稳定时间和粉质质量指数显著提升（P<0.05）,全麦粉的弱化度显著降低（P<0.05）,微波、蒸汽和挤压组的脂肪酶及脂肪氧化酶的活力显著降低（P<0.05）;在全麦粉贮藏期间,挤压和蒸汽组的脂肪酸值较低（<120 mg/100 g）,且上升缓慢,改善了全麦粉稳定性,而微波组的脂肪酸值上升较快,且脂肪酸值较高（>120 mg/100 g）。挤压和蒸汽组的多酚和黄酮含量及多酚对ABTS+·清除能力和氧自由基吸收能力均显著低于微波组（P<0.05）。根据全麦粉的贮藏稳定性和全麦面团的品质,麸皮常压蒸汽稳定化处理适合于全麦粉加工。     

不同加工方式对米糠粉食品配料理化特性的影响

为了改善米糠的理化特性,开发新型米糠食品配料,本文研究了挤压膨化、微波蒸煮和高温焙炒三种整体加工方式对脱脂米糠理化特性的影响。结果表明,脱脂米糠经过三种整体加工方式处理后,理化特性均得到改善,其中挤压膨化米糠具有最高的水溶性指数、吸水性指数、糊化度及分散稳定性。与未处理组相比,挤压膨化米糠水溶性指数、吸水性指数和糊化度分别提高了4.82%、18.92%和96.04%。同时,三种整体加工方式显著减少了米糠中还原糖和植酸的含量,而分析米糠的酚类物质和抗氧化活性时,发现高温焙炒显著增加了脱脂米糠中总酚含量及抗氧化能力,但挤压膨化降低了脱脂米糠中总酚含量和抗氧化能力。本研究可以为脱脂米糠作为糊粉类营养代餐食品配料的加工提供指导。     

基于GC-IMS和HS-SPME-GC-MS的不同处理方式分析黑枣挥发性成分

以壶瓶枣为原料，采用三蒸三制、外源美拉德反应液、三蒸三制＋外源美拉德反应液、外源多酚氧化酶、三蒸三制＋外源多酚氧化酶液5 种方式处理制备黑枣，利用气相离子迁移谱（gas chromatography-ion mobility spectrometry，GC-IMS）技术和顶空固相微萃取结合气相色谱-质谱（headspace solid phase microextraction-gas chromatography-mass spectrometry，HS-SPME-GC-MS）联用技术测定黑枣产品挥发性成分，并对结果进行主成分分析和聚类分析，分析不同处理对黑枣风味品质的影响。结果表明：不同处理方式得到的主要挥发性成分各不相同，GC-MS和GC-IMS两种检测方法检出的基础风味物质种类基本一致，共有风味物质为6～10 种。不同处理方式检测到6 种黑枣中均含有糠醛、庚醛、壬醛、正辛醛、冰醋酸。三蒸三制处理可以增加黑枣的风味。同时说明，GC-IMS技术可应用于快速鉴定和差异分析不同黑枣样品挥发性成分，为改进黑枣加工工艺及褐变机制提供理论依据。     

Total phenolic content and antioxidant properties of eclipse black beans (Phaseolus vulgaris L.) as affected by processing methods

ABSTRACT:  The effects of soaking, boiling, and steaming processes on the phenolic components and antioxidant activity of black beans were investigated. All processed beans exhibited significantly ( P < 0.05) lower antioxidant activities than raw beans in total phenolic content (TPC), DPPH free radical scavenging activity (DPPH), and oxygen radical absorbing capacity (ORAC). Steaming processes resulted in a greater retention of TPC and ORAC values than the boiling processes. Pressure boiling shortened processing time compared to regular boiling, resulted in insignificant differences in TPC, but significantly increased in ORAC as compared to the regular boiling method. Pressure steaming resulted in significant decreases in TPC, DPPH, while significantly increased in ORAC compared to regular steaming. Greater TPC, DPPH, and ORAC values were detected in boiling water than in the soaking and steaming water. Mass balance analysis showed that boiling caused more dry solid loss than steaming. All of these results indicated that processing methods significantly changed contents and activities of antioxidant components of black beans. Steam processing exhibited several advantages in appearance and texture of the cooked product, shortening processing time, and in greater retention of TPC and antioxidant activities. Steam processing may be used to develop high-quality health-promoting black bean products.     

烘焙度对冷萃咖啡理化指标与风味成分的影响

以亚洲咖啡豆为研究对象,分别选取浅、中、深3 种烘焙度的中国云南和印度尼西亚苏门答腊产的卡蒂姆种咖啡豆,比较分析冷萃与热萃方式对萃取浓度、萃取率、可滴定酸、总酚、总糖、咖啡因、葫芦巴碱、绿原酸、抗氧化活性与挥发性成分的差异,并进行主成分分析,从而探究烘焙度对冷萃咖啡理化指标与风味成分的影响规律。结果表明,随着烘焙度增加,冷萃咖啡的萃取浓度、萃取率均显著上升,可滴定酸、总酚、葫芦巴碱、绿原酸、抗氧化活性均显著下降（P＜0.05）。冷萃咖啡较热萃咖啡拥有更高的萃取浓度、萃取率与总糖含量（P＜0.05）,而可滴定酸、总酚含量、抗氧化活性较热萃显著偏低（P＜0.05）。经顶空固相微萃取-气相色谱-质谱检测分析发现,浅烘咖啡豆萃取液中的挥发性成分含量显著低于烘焙度高的咖啡萃取液,深烘咖啡豆萃取液中挥发性成分种类与总含量最多。进一步通过主成分分析能较好区分冷萃和热萃咖啡,两者挥发性成分贡献率具有较大差异。2-丁酮、2-丁烯醛等花香类物质对浅烘冷萃咖啡贡献率更高,而2-甲基吡嗪、糠醇等呈现烘焙坚果类香气物质对浅烘热萃咖啡贡献率更高;2,6-二乙基吡嗪、川芎嗪等烘焙坚果类香气物质对中烘冷萃和热萃咖啡具有较高的贡献率;2-乙烯基呋喃、甲基糠硫醇、2,5-二乙基吡嗪、糠基甲基硫醚等物质对深烘冷萃咖啡有较高贡献率,二甲基二硫、对甲酚、1-甲基吡咯等物质对深烘热萃咖啡贡献率更高。相对于热萃咖啡,烘焙度对冷萃咖啡抗氧化能力与挥发性成分的影响更大。     

负氧化还原电位电解水冷泡绿茶茶汤理化特性、抗氧化性能及香气成分研究

以瓶装饮用天然水冷泡绿茶和常规热泡绿茶作为对比,探讨负氧化还原电位电解水对冷泡绿茶茶汤品质的影响,以期为得到活性成分含量高及抗氧化活性强的冷泡绿茶饮品提供新选择。通过调节电解饮用水时间电解生成不同负氧化还原电位电解水1和2;通过紫外分光光度法、高效液相色谱法以及顶空固相微萃取与气相色谱-质谱联用法测定并比较负氧化还原电位电解水、瓶装饮用天然水冷泡绿茶和常规热泡绿茶茶汤基本理化指标、主要活性成分含量、抗氧化性、感官品质和香气成分。结果表明,负氧化还原电位电解水冷泡绿茶茶汤pH呈弱碱性,氧化还原电位为负值,可溶性固形物含量及茶汤浸提率显著高于瓶装饮用天然水冷泡绿茶（P<0.05）,与常规热泡茶相当;电解水制得茶汤色度黄绿明亮,汤色品质高;电解水茶汤多酚含量显著高于瓶装饮用天然水冷泡,且电解水样2显著高于常规热泡（P<0.05）,游离氨基酸总量显著高于瓶装饮用天然水冷泡以及常规热泡（P<0.05）,咖啡碱含量低于常规热泡,儿茶素类含量均高于瓶装饮用天然水冷泡,除EGCG和EGC外均高于常规热泡;电解水冷泡茶茶汤抗氧化能力显著高于其他两种绿茶茶汤（P<0.05）;电解水冷泡茶汤感官评分最高且茶汤香气成分最为丰富醇和。实验初步验证了负氧化还原电位电解水用作冷泡绿茶加工用水可行性,且筛选出电解水样2制得绿茶茶汤生化成分高、抗氧化活性强且感官评价得分高、香气清香持久。     

Effect of thermal processing on antioxidant properties of purple wheat bran

Antioxidant activity of purple wheat bran, heat-treated purple wheat bran, and purple wheat bran muffins was evaluated to determine the impact of thermal processing on potential health benefits. The purple wheat bran and muffin samples were analyzed for total phenolic content, anthocyanin content and free radical scavenging activity using peroxyl (oxygen radical absorbance capacity assay) and 2,2-diphenyl-1-picrylhydrazyl (DPPH assay) radicals. Total phenolic content and oxygen radical absorbance capacity (ORAC) values of sample extracts were significantly affected by various extracting solvents. The conditions selected for heat treatment did not markedly change antioxidant activity of purple wheat bran. However, there was a significant reduction in total phenolic contents, ORAC values and total anthocyanins during processing of purple wheat bran- or heat-treated purple wheat bran-enriched muffins. On the contrary, muffin extracts still remained excellent in DPPH radical scavenging activity.     

固态发酵对麸皮抗氧化特性及全麦面包感官品质的提升作用

用植物乳杆菌LB-1和酿酒酵母对小麦麸皮进行固态发酵,利用发酵麸皮重组全麦粉制备全麦面包,并对固态发酵麸皮的抗氧化特性及全麦面包的色泽、组织结构、风味、口感等感官品质进行分析.结果表明:经过乳酸菌LB-1与酵母菌协同发酵36?h后,麸皮的总游离氨基酸、可溶性蛋白、可溶性多酚和可溶性阿拉伯木聚糖分别增加了0.44、0.8...     

不同采收期香椿茶发酵前后活性成分、降糖活性及其挥发性成分比较分析

以4～6月香椿嫩芽制备的香椿发酵茶为研究材料,探讨不同采收期香椿茶发酵前后6个样品中主要活性成分、抗氧化活性、降糖活性及挥发性成分的差异,揭示香椿发酵茶品质随采收期的变化规律,确定香椿发酵茶最适的采收期.结果表明:6个样品的主要活性成分、抗氧化和降糖活性具有显著性差异,挥发性成分各有特色.随着采收期的延长,香椿茶发酵前...     

Characterization of the flavor compounds in wheat bran and biochemical conversion for application in food

Wheat bran, an abundant and low-cost by-product from agricultural processing, can be used as an alternative food resource. Biochemical conversion of wheat bran to food ingredient involves pretreatments of bran to enhance its acceptability. In this work, the effects of the Maillard reaction and enzymolysis on flavor properties of wheat bran and sensory evaluation of steamed buns fortified with wheat bran were analyzed using GC-MS combined with sensory evaluation. The results showed that the Maillard reaction and enzymatic hydrolysis, as well as flavoring process, could effectively improve the flavor profiles of wheat bran. The flavor compounds in modified wheat bran products as well as its fuzzy sensory score increased significantly (P < 0.05) compared with those in commercially available dry malt extract. Additionally, steamed buns fortified with wheat bran had enhanced flavor and overall acceptability. The study can be useful in valorization a plethora of grain bran (waste) into valuable resources.     

Phytochemical profiles of black and yellow soybeans as affected by roasting

The current research aimed to compare the changes of phytochemicals, antioxidants, and anti-nutritional factors of yellow and black soybeans upon roasting. Yellow soybean was roasted at 210°C for 35 min and 230°C for 25 min, and black soybean was roasted at 210°C for 30 min and 230°C for 25 min. Isoflavones were significantly increased after the roasting process, while trypsin inhibitor was significantly decreased. The roasting process combined with the soaking process led to decrease in anthocyanin, soyasaponin, and antioxidant capacities. Black soybeans had more apparent variations in compounds than the yellow soybeans. For black soybeans, the processing under 230°C for 25 min presented more decrease in trypsin inhibitor and anthocyanin content. The roasting at a high temperature and short time produced products with a light color. Roasting combined with the soaking process had negative impacts on both yellow and black soybeans, but there were slight differences in the resultant compounds between different roasting temperatures.     

Enhanced antioxidant and antidiabetic activities of barley and wheat after soaking with tea catechin

Barley and wheat were investigated as natural α-glucosidase inhibitors having potent inhibitory activities against the antidiabetic enzymes α-glucosidase, maltase, and sucrase. After soaking with tea catechin as an elicitor, extracts of barley and wheat were prepared using thermal treatment in an autoclave at 121°C for 15 min, then the in vitro antioxidant and antidiabetic activities were determined. The total soluble phenolics contents of barley and wheat during soaking were increased by addition of tea catechin, which also contributed to the peroxyl radical-scavenging activity and the reducing capacity. The rat α-glucosidase, maltase, and sucrase inhibitory activities of barley were increased with an increase in the added tea catechin concentration from 0.1% to 0.5%. Tea catechin may have a role as an elicitor for production of phenolics that exhibit antioxidant activities and rat-intestinal maltase and sucrase inhibitory activities during the soaking process of barley and wheat.     

焙火时间对武夷岩茶肉桂香气品质的影响

目的 探讨焙火时间对武夷岩茶(肉桂)香气品质的影响.方法 采用传统炭焙工艺处理[参数为温度(130±5)℃、时间持续16 h]武夷肉桂毛茶,以炭焙时间4 h间隔取样,一共得到5个供测试样(毛茶、炭焙4 h、炭焙8h、炭焙12h、炭焙16h),样品前处理采用顶空-固相微萃取方法,然后用气相色谱-质谱法分离鉴定其香气成分,...     

稻谷水热加工过程中镉迁移规律研究

目的研究稻谷在蒸谷米水热加工过程中镉的迁移规律。方法以蒸谷米小试装置及生产线采集样品为研究对象,在优化碾米时间的基础上,在排除水分含量差异对测定结果的前提下,利用统计分析考察水热工艺(浸泡和蒸煮)对稻谷各部分(稻壳、米糠和精米)镉含量的影响。结果由实验数据推断,在水热过程中,镉的迁移主要发生在稻谷的内部,且主要是在浸泡时从精米向米糠迁移富集,而蒸煮工艺则对镉的分布变化影响很小;经过浸泡,精米中的镉含量可降低约40%;推测热水的浸泡一方面使胚乳淀粉分子间游离的镉部分溶出,一方面促使镉向络合能力更强的米糠蛋白迁移,最终导致其分布发生明显变化。结论该研究为在稻谷加工过程中实现重金属镉的消减提供了科学依据。     

Effect of thermal and non-thermal processing on antioxidant potential of cowpea seeds

Legumes are a good source of bioactive components, besides being nutrient dense. These components have antioxidant properties and have a protective role against free radicals. Legumes like cowpeas are usually consumed after certain processing, so the present study was intended to assess antioxidant property of selected four cultivars of cowpea after going through various thermal (autoclaving, microwave, boiling, and roasting) and non-thermal (soaking and fermentation) processings. Thermal processing reduced total phenolic content (TPC), total flavonoid content (TFC), and ferric reducing antioxidant power (FRAP) in all cultivars with respect to antioxidant activity of raw cultivars, while DPPH scavenging activity increased after all thermal treatments excluding few thermal processings. Non-thermal processing revealed increase in TPC, DPPH scavenging activity, and FRAP values, while TFC content showed a decreasing trend. A moderately high correlation between TPC and DPPH scavenging activity was observed in both kinds of thermal treatments indicating the role of phenolic compounds for antioxidant activity. It was concluded from the study that fermentation processing has promising effects on retention and enhancement of antioxidant activity of cowpea cultivars.