Antioxidants and shelf life of whole wheat bread

Industrially produced bread normally operates with a shelf life of several weeks at room temperature and indications of storage-related off-flavour development as a consequence of lipid oxidation have been suggested. The present study has tested enrichment of whole wheat bread with α-tocopherol or commercially used rosemary extracts for production of bread loaves with higher oxidative stability and hence better overall sensory quality. Bread quality was evaluated by sensory profiling, determination of antioxidative capacity, determination of lipid hydroperoxides as primary oxidation products, and analysis of volatile compounds including secondary lipid oxidation products. Enrichment of bread with α-tocopherol resulted in higher degrees of rancid aroma and flavour in fresh samples, which was explained by higher levels of secondary oxidation products, whereas enrichment of bread with rosemary extracts did not have any effect. Accordingly, application of antioxidants cannot, based on the current data, be recommended for achievement of bread with improved sensory properties during storage.     

Effect of heat treatment on the flavor of oat flakes

In order to assess the effect of heat treatment procedure on the flavor and volatile compounds of oats, raw oats, kiln and dried oats, dehulled oats and oat flakes were analysed. A sensory profile method was used to monitor changes in flavor. It changed from hay-like for raw oats into nutty, bread-like for oat flakes. Headspace solid phase microextraction (SPME) and solvent assisted flavor evaporation (SAFE) techniques were applied for isolation of aroma compounds. The most abundant compound in headspace was hexanal – its concentration varied from 176 to 1671 μg/kg depending on the processing stage. The key aroma compounds of oat flakes identified using gas chromatography – olfactometry and aroma extract dilution analysis (AEDA) were 2-methyl-3-furanthiol with roast/cooked oatmeal flavor together with methional, dimethyl trisulfide, 1-octen-3-ol, 2-methyl-3,5-diethylpyrazine.     

Effect of kneading and baking on the degradation of the lipid fraction of biscuits

An experimental investigation was carried out with the aim of evaluating the effect of kneading and baking on the degradation of the lipid fraction of biscuits. For this purpose, the raw materials, the dough, and the end-products sampled during processing at a biscuit-making industrial plant were analysed. The results showed that the kneading stage caused a significant decrease in content of polyunsaturated fatty acids and a concomitant significant increase of triacylglycerol oligopolymers and oxidised triacylglycerols that are indexes of oxidative degradation. The subsequent baking step caused the degradation of part of the oxidised compounds to volatile substances, as confirmed by the determination of the p-anisidine value. On the whole, the biscuit-making process, although determining a significant increase of triacylglycerol oligopolymers, has only a small impact on the oxidation level of raw materials.     

直火和蒸汽加热方式制备豆乳对豆腐风味的影响

通过感官评价和化学分析的方法研究了直火与蒸汽2种加热方式制备豆乳对内酯豆腐风味的影响。感官评价结果表明:直火法豆腐的豆腥味和青草味与蒸汽法相当,而豆香味、甜香味和酸味高于蒸汽豆腐,说明直火豆腐的风味要浓于蒸汽豆腐。采用固相萃取法提取豆腐中风味化合物,通过气相色谱-质谱联用法对风味成分进行了检测,结果表明:乙酸乙酯、甲基环戊烷、苯、正戊醛、1-戊醇、已醛、乙苯、邻二甲苯、间二甲苯、N,N-二甲基乙酰胺、1-辛烯-3-醇、戊酸、丁酸丁酯是直火、蒸汽加热制备的豆腐均存在的风味化合物,此外,甲苯、3-羟基丁醛、已酸、苯甲酸甲酯和苯并呋喃为直火豆腐特有化合物,而氮杂丁烷、丙二酸二乙酯、二甲胺和芍药醇为蒸汽豆腐特有化合物。     

Chemical composition and sensory characteristics of oat flakes: A comparative study of naked oat flakes from China and hulled oat flakes from western countries

Oats are generally considered as a health food and widely accepted by human beings nowadays. Oat flakes are the main commercial oat products around the world. In order to understand the chemical composition and sensory characteristics of the naked oat flakes from China and the hulled oat flakes from western countries, 37 flake samples from China and 44 samples from western countries (8 from the USA, 8 from Canada, 5 from Sweden, 8 from Denmark, 7 from the United Kingdom, and 8 from New Zealand) were investigated in the present study. The results indicated that naked oat flakes showed significantly higher (P < 0.01) contents of lipid and Na, a higher level of whiteness (P < 0.05) and lower (P < 0.01) contents of β-glucan and Fe, compared to hulled oat flakes from western countries. No significant differences of Zn, Ca, and total ash contents were observed between naked oat flakes and hulled oat flakes. In addition, naked oat flakes showed significantly higher water absorption index at room temperature (P < 0.01) when compared with hulled oat flakes. Hulled oat flakes showed higher sensory evaluation score than naked oat flakes (P < 0.01).     

不同萎凋方式和碰青工艺对红茶挥发性成分的影响

为探明萎凋方式和碰青工艺对红茶香气形成的影响,以金萱为材料,采用顶空固相微萃取和气相色谱—质谱联用分析技术(HS-SPME-GC-MS)结合茶叶感官审评,研究红茶可挥发性成分和香气前体物的变化规律。结果表明,改变萎凋方式或引入碰青工艺对金萱红茶主要挥发性成分并没有很大作用,但可引起挥发性成分相对含量变化,导致茶叶香型发生改变。日光和鼓风萎凋对金萱红茶香型差异性有积极作用。抽湿萎凋和碰青工艺则增强香气的丰富度和持久性。鉴定的48种挥发性化合物中主要为醇类,占香气总量的71.58%~74.19%。反-β-罗勒烯是区别于其他红茶的主要成分之一。茶叶前体物产生的挥发性成分呈规律性变化,日光萎凋有利于苯丙氨酸和法呢基焦磷酸/牻牛儿基焦磷酸为前体的挥发性成分产生;鼓风和抽湿萎凋则以不饱和脂肪酸降解的挥发性成分为主。碰青工艺对来自苯丙氨酸和类胡萝卜素的挥发性成分有积极作用,但与静置时间成负相关。本研究结果为乌龙茶品种改制红茶提供理论参考。     

Metabolic profiling and analysis of volatile composition of durum wheat semolina and pasta

Although pasta is generally not considered for its aromatic properties, some evidence proves that cereal flours release volatile compounds and they might have an effect on the aroma of the transformed products. This work reports on the characterization of the volatile components of semolina and pasta obtained from four durum wheat cultivars (Triticum durum Desf., cvs. PR22D89, Creso, Cappelli, Trinakria). Semolina samples were characterized through polar metabolite profiling and fatty acid analysis to identify potential precursors of the volatile components. The results show significant differences among the samples tested with cv. Trinakria characterized by the highest content of sugars and fatty acids. Volatile composition was investigated both in semolina and in cooked pasta using headspace solid-phase micro-extraction (HS-SPME) and identified by GC–MS. Thirty-five volatile compounds including aldehydes, ketones, alcohols, terpenes, esters, hydrocarbons and a furan were identified. Significant differences were observed between semolina and pasta samples in terms of composition and amount of the volatile compounds. During cooking an increase in aldehyde content, the appearance of ketones and a decrease in alcohol content were observed. Correlations between metabolites and volatiles demonstrate that the flavour of cooked pasta may differ significantly depending on the durum wheat cultivar employed.     

烘焙温度对九龙袍品种乌龙茶生化品质的影响

采用九龙袍品种颗粒型乌龙茶的毛茶样为材料,在120℃（高火）、100℃（中火）和80℃（低火）3个温度下分别烘焙2βh,分析比较了不同烘焙温度对颗粒型乌龙茶感官品质、主要理化成分及挥发性成分的影响。感官审评结果表明,低温烘焙（80℃）茶样的感官审评得分最高,且香气和滋味最好;化学成分分析表明,水浸出物和氨基酸总量随着烘焙温度的升高呈现明显的降低趋势,而儿茶素总量、咖啡碱、黄酮化合物等随着温度的升高变化不显著;此外,茶氨酸、天冬氨酸、丝氨酸、谷氨酸等氨基酸成分随着烘焙温度的升高而降低,而EGC、C等儿茶素成分含量随着烘焙温度的升高而升高;挥发性成分分析表明,随着烘焙温度的升高,醇类、酮类、酯类物质以及含氮化合物的相对含量均呈现降低趋势,碳氢化合物含量呈现上升的趋势;具有清新花香的挥发性成分（如β-芳樟醇及其氧化物、橙花叔醇、己酸叶醇酯、异戊酸己酯、β-丁酸苯乙酯、苯甲酸己酯、茉莉酸甲酯、己酸己酯、α-紫罗酮、香叶基丙酮、顺-茉莉酮、吲哚等）的相对含量随烘焙温度的升高而降低,而碳氢化合物成分（如β-月桂烯、柠檬烯、5-甲基-辛-1,3-二烯、2,4,6-三甲基-1,3,6-庚三烯、β-倍半水芹烯、十二烷等）以及含氮化合物（如苯乙腈等）相对含量随着烘焙温度的升高呈现大量增加的趋势。     

“春闺”绿茶香气成分鉴定分析

采摘“春闺”茶树品种一芽二、三叶鲜叶原料,按烘青绿茶工艺制样。连续3年感官审评结果表明,“春闺”品种适制绿茶,制绿茶干茶紧结,色泽绿润,味醇爽回甘,茶汤有特殊的花香;采用顶空-固相微萃取(HS-SPME)法富集其香气物质,并利用GC-MS进行香气成分鉴定,结果表明,春闺烘青绿茶共鉴定出70余种香气化合物,其主要香气成分是橙花叔醇(20.2%)、α-法呢烯(16.96%)、吲哚(13.57%)、反-β-罗勒烯(6.74%)、己酸叶醇酯(3.99%)、壬醛(2.03%)、2-甲基-6-亚甲基-1,7-辛二烯-3-酮(4.61%)、顺-茉莉酮(2.13%)、苯乙醛(1.35%)、己酸己酯(1.28%)、石竹烯(1.34%)等;与绿茶对照种“福鼎大白茶”对比分析发现,春闺绿茶的醇类组分(21.85%)远高于福鼎大白茶绿茶(6.56%),烯烃类(37%)和含氮化合物(15.15%)也比福鼎大白茶绿茶高;而醛类、酮类、酯类、杂氧化合物等低于福鼎大白茶绿茶。     

利用SPME-GC×GC/TOFMS对香草兰中挥发、半挥发性成分萃取与分析研究

利用固相微萃取(SPME)法萃取香草兰中挥发和半挥发性的成分,再结合全二维气相色谱/飞行时间质谱(GC×GC/TOFMS)技术进行定性分析。试验共鉴定出香草兰中181种挥发、半挥发性化合物,其中含量较高的成分主要有香兰素、呋喃甲醛、(2S,3S)-(+)-2,3-丁二醇、邻甲氧基苯酚、2,3-丁二醇、苯酚、正己醛、(2R,3R)-(-)-2,3-丁二醇、对羟基苯甲醛、3-甲基丁酸、2,3,5,6-四甲基吡嗪、3-羟基-2-丁酮、香草酸、壬醛、正己酸、1-辛烯-3-酮。结果表明,GC×GC/TOFMS高分辨率和高灵敏度的特点非常适合复杂组分体系的定性分析。     

部分徐麦品种（系）馒头的挥发性物质和质构分析

为明确不同徐麦品种（系）馒头制品的挥发性物质和质构特征,本研究利用顶空固相微萃取(HS-SPME)技术结合气相色谱-质谱法(GC-MS)对5个徐麦品种（系）馒头制品的挥发性物质进行分析,并利用TMS-PRO质构仪进行了TPA检测。结果表明,馒头中挥发性成分有41种,包括醇类（1种）、醛类（2种）、酯类（13种）、烷类（10种）、烯类（4种）、苯类（8种）、酮类（2种）以及醚类（1种）化合物。含有挥发性物质种类最多的品种是徐麦178（29种）,最少的品种是徐麦39（22种）。TPA检测数据显示,徐麦178制作的馒头具有较高的硬度、弹性和粘性;徐麦39的质地较为柔软。不同品种（系）馒头因为挥发性物质间的相互作用、种类数、含量以及硬度、弹性和粘性等的不同具有了独特的风味和口感。     

Processing characteristics of Solanum tuberosum—S. stoloniferum hybrids

Two hybrids having high total solids were compared with established commercial varieties for processing into french fries, potato chips, and potato flakes. Russet Burbank was used as a control for potato flakes and french fries, and Kennebec for potato chips. The hybrids were processed initially at harvest and at two intervals after harvest. The solids in the hybrids varied from 23.0% to 26.9% and the products generally had a better color and yielded more product per pound of raw material than the controls. The hybrids had a high level of xanthophyl, stable in the french fries and potato chips but unstable in the potato flakes. Antioxidants retarded the loss of the yellow color in the flakes. Oil absorption was found to be inversely related to solids in the potato chips and french fries. By means of sensory evaluation, the hybrids were generally considered different from the controls with respect to color, flavor, and texture but no preferences were obtained. Potatoes with high solids result in more finished product per pound of raw material.     

春闺品种花香红茶发酵过程中生化成分的变化研究

为研究茶叶品质成分在红茶发酵过程的动态变化,探索春闺品种花香红茶适宜的发酵工艺参数,选择新品种春闺春季鲜叶原料进行花香红茶制作,检测其在发酵过程中[0、2、4、6 h （毛茶样）分别取样]的生化与感官品质的变化。结果表明,主要生化成分如茶多酚、水浸出物、游离氨基酸总量、黄酮总量随着发酵时间的延长呈减少的趋势,分别从36．1％、16．27％、3．54％、8．93％减少至30．77％、11．25％、3．2％、7．85％;茶黄素、茶红素含量随着发酵时间的延长含量总体呈增加趋势,分别从0．52％、2．26％增加到0．84％、2．58％。在香气组成上,春闺品种花香红茶主要以醇类、醛类、酯类、含氮化合物和碳氢化合物为主,其中醇类、含氮化合物含量随着发酵时间的延长而降低,而醛类、酯类和碳氢化合物含量却呈升高趋势;春闺品种花香红茶香气成分主要包括橙花叔醇（18．02％）、α-法呢烯（12．4％）、β-罗勒烯（7．89％）、吲哚（6．8％）、己酸叶醇酯（5．83％）、芳樟醇（5．52％）、香叶醇（5．45％）等;感官审评结果表明,随着发酵时间的延长,春闺花香红茶品质逐渐向好的方向发展：汤色由原先的橙红稍暗变化为红艳明亮、显金圈;滋味由苦涩向甜醇转化,香气也由稍浊带青气向花果香、甜香转化。     

气相色谱-质谱联用法对菠萝、杧果和米蕉混酿果酒的香气物质的分析

采用气相色谱-质谱（GC-MS）联用法对菠萝、杧果和米蕉果实混酿的果酒的香气物质进行了分析.结果表明,菠萝、杧果和米蕉混酿果酒的香气物质的化学成分与菠萝果酒有显著差异,其中混酿果酒的香气物质更为丰富,尤其是包含着更多的中、高沸点的香气物质.这为感观评价提供了仪器分析依据.     

Sensory evaluation as a tool in breeding potatoes for French fries and flakes

Standardized sensory evaluation of advanced breeding clones developed in the research program of the Horticulture Department at North Dakota State University has been conducted annually since 1980. Procedures used by the USDA-ARS Potato Research Laboratory for processing tubers into partially fried french fries or flakes are described along with the procedures used for finish-frying of the fries and rehydrating the flakes in preparation for sensory evaluation in the Food and Nutrition Department at North Dakota State University. Following brief training, panelists evaluate the fries and flakes from each clone in triplicate for color, flavor, and texture. Procedures for determining length of fries and limpness of fry strips are described. Samples of 334 clones prepared as french fries and 135 clones prepared as flakes have been evaluated. Examples are given of types of data collected with interpretation of results in relationship to their use in the breeding program.     

红茶烟用香料的制备、分析及应用

以滇红茶为原料通过特殊工艺制得一具有滇红茶特征茶香、略带花香和烘烤香韵的烟用香料,采用同时蒸馏萃取(SDE)装置收集其挥发性成分,并以气相色谱-质谱法(GC-MS)对其挥发性成分进行分离和鉴定,共检出48种化合物,其中有香叶醇、芳樟醇、苯乙醇和苯甲醇等烟草本香物质及2-甲基丁酸、己酸等低级脂肪酸,苯乙醛、苯甲醛、3-甲基丁醛等烟草重要致香物质。将该香料用于卷烟加香,能够明显丰富烟香,减小刺激性和改善卷烟余味。     

嫁接对红色樱桃番茄果实挥发性风味物质的影响

为探究嫁接对红色樱桃番茄果实挥发性风味物质的影响,采用顶空固相微萃取-气相色谱-质谱联用技术对3个红色樱桃番茄品种实生苗和嫁接苗果实的挥发性风味物质的种类和相对含量进行了分析。结果表明,CT18013S含有57种挥发性物质,包括5种特有成分,其中庚醛为主要风味物质;CT18013J含有69种挥发性物质,包括17种特有成分,其中乙酸丁酯和愈创木酚为主要风味物质。粉星S含有52种挥发性物质,包括3种特有成分;粉星J含有60种挥发性物质,包括11种特有成分,其中1-硝基-2-苯乙烷为主要风味物质。红星S含有57种挥发性物质,包括6种特有成分;红星J含有64种挥发性物质,包括13种特有成分,其中庚醛、苯乙腈、1-硝基-2-苯乙烷、E,E-2,4-癸二烯醛为主要风味物质。综合比较3个红色樱桃番茄品种实生苗和嫁接苗果实挥发性风味物质发现,嫁接苗挥发性风味物质的种类数量均高于实生苗。与实生苗相比,嫁接提高了3个红色樱桃番茄品种果实中苯乙醇、E-2-庚烯醛、苯乙醛和正壬醛的含量。本研究为进一步解析番茄风味调控提供了科学依据。     

不同风味类型铁观音乌龙茶香气组成化学模式识别研究

铁观音乌龙茶按现行国家标准可划分“清香型”、“浓香型”和“陈香型”3种风味类型。本试验在对安溪铁观音收集和审评分类基础上,采用顶空固相微萃取和气相色谱-质谱联用法（HS-SPME/GC-MS）对各茶样进行香气成分检测,并通过主成分分析（PCA）、正交偏最小二乘判别分析（OPLS-DA）等可视化模式识别方法比较了不同风味铁观音新茶和不同质量等级铁观音陈茶香气组成的特征差异。结果表明：（1）铁观音新茶和陈茶香气组成的化学模式存在明显的类群区分。铁观音新茶相较陈茶具有更为丰富的香气组分,其中醇类、酯类和烯烃类化合物是铁观音新茶“清新”风味的主要赋香成分,而醛类和酮类化合物则是形成铁观音“陈香”风味的重要物质基础。橙花叔醇、吲哚、α-法呢烯、2-甲基丁酸-2-苯乙酯、己酸-顺式-3-己烯酯、2-甲基苯基甲酸甲酯、丁酸苯乙酯、2-甲基丙酸-2-苯基乙酯、2-苄基（苯甲基）异氰化、己酸异戊酯和香叶基丙酮可作为区分铁观音新茶和陈茶的主要特征香气成分。（2）铁观音新茶按其香气组成可划分为“显酸茶”、“正韵茶和青韵茶”、“浓香茶”3个茶样类群。带“酸香”风味的“显酸茶”主要与酯类化合物密切相关,而显“火香”风味的“浓香茶”香气成分多为长链缩合态化合物,且二者均较“正韵茶和青韵茶”香气组成更为丰富。（3）不同贮藏年份的铁观音陈茶香气组成无明显的类群区分,但有潜在的质量等级差异。高级铁观音陈茶的酯类化合物相对丰富,醛类和酮类化合物含量相对较低。该研究结果可为铁观音产品的分类鉴别和风味品质评价提供参考。     

武夷大红袍初制过程中香型与香气成分的变化规律

采用顶空固相微萃取/气相色谱-质谱联用技术对武夷大红袍初制过程在制叶的香气成分进行了分析,结果表明,与鲜叶相比,以壬醛、十四烷、十三烷、十二烷、丁酸-2-乙基-1,2,3-丙三酯、二-叔-十二烷基二硫化物和乙酸橙花叔酯为代表的烷烃类、醛类和酮类组分等香气成分随着初制工序的进展呈下降趋势,且降幅较大,在毛茶中的含量分别下降了72.4%、91.8%、63.6%;而以橙花叔醇、α-法尼烯、吲哚、苯乙腈、苯乙醇、己酸己酯、己酸-顺3-己烯酯、己酸-反2-己烯酯、苯甲酸己酯、苯甲酸-3-己烯-1-酯和苯甲酸反2-己烯酯为代表的构成大红袍的特征性香型的醇类、酯类和烯烃类香气成分在初制过程中大量转化生成,在毛茶中的含量分别增加了215.5%、70.8%、682.6%。     

外源添加糖及氨基酸对咖啡果皮酒风味和感官品质的影响

为探究不同外源添加物对咖啡果皮酒风味和感官品质的影响,本研究添加4种可发酵糖（葡萄糖、果糖、麦芽糖和蔗糖）和2种可发酵氨基酸（精氨酸和谷氨酸）发酵生产咖啡果皮酒。以顶空固相微萃取-气相质谱法结合感官评价,分析外源添加物对咖啡果皮酒风味和感官品质的影响。结果表明:共检出9大类75种风味组分,以酯类和醇类为主;添加可发酵糖能显著增加咖啡果皮酒醇类组分（23.99%~121.24%）,添加可发酵氨基酸咖啡果皮酒能增加酯类组分（25.77%~28.18%）,而添加可发酵糖咖啡果皮酒酯类组分显著减少（10.81%~69.94%）;方差齐性检验P=0.206>0.05,在α=0.05的水平上各外源添加物果酒风味组分没有显著性差异,事后两两比较P=(0.371~0.989)>0.05,说明样品间差异不显著,但PCA分析（PC1:96.01%,PC2:3.13%）能将其完全区分;使用模糊数学法感官评判发现,添加精氨酸所酿造的果酒综合得分最高（92.40）,更加适合人们的口味,整体风格显著,协调性好,谷氨酸添加次之（80.80）,果糖和蔗糖所酿造的咖啡果皮酒综合评分一致（78.20）,添加麦芽糖果酒得分最低（74.20）。综上所述,添加氨基酸可改善咖啡果皮酒风味和口感,发酵糖改善效果不如氨基酸。