Modifications in aroma characteristics of'Merlot'dry red wines aged in American,French and Slovakian oak barrels with different toasting degrees

Aging in oak barrels is widely used in enology which could bring flavor changes and aromatic complexity to wines.In the present study,the aroma compounds were analyzed from the‘Merlot’dry red wines,which were fermented in two types of fermenters(stainless steel tank and rotated oak barrel)and aged in six types of oak barrels(three geographic origins×two toasting degrees)for different time(0,3,6 and 9 months,respectively).Results showed that 30 volatiles were associated with barrels and increased during oak aging.The fermenters could influence the intensities of the toast,leathery,smoky,fruity,floral and caramel aromas.The concentration of whisky lactone,eugenol,cis-isoeugenol,and the intensities of the toast and spicy aromas were highest in the wines aged in American oak and were lowest in the wines aged in French oak barrels.The concentrations of guaiacol,syringol,trans-isoeugenol,furfural alcohol,vanilla,cis-whisky lactone enabled the medium toasting barrels to be distinguished from the light toasting ones.The compounds originating from the barrels could be used to distinguish the types of different barrels,but the other general grape-derived and fermentation-derived volatiles could not.The fermenters,oak species and toasting degrees of the barrels all had significant effects on the aroma profiles of the aged‘Merlot’dry red wines,but the influence of the geographic origin was not obvious.

Plant-Derived Enzymes Producing Chiral Aroma Compounds and Potential Application

Aroma(volatile)compounds play important ecological functions in plants,and also contribute to the quality of plant-derived foods.Moreover,chiral aroma compounds affect their functions in plants and lead to different flavor quality properties.Formations of chiral aroma compounds are due to the presence of enzymes producing these compounds in plants,which are generally involved in the final biosynthetic step of the aroma compounds.Here,we review recent progress in research on the plant-derived enzymes producing chiral aroma compounds,and their changes in response to environmental factors.The chiral aroma enzymes that have been reported produce(R)-linalool,(S)-linalool,(R)-limonene,and(S)-limonene,etc.,and these enzymes are found in various plant species.We also discuss the origins of enantioselectivity in the plant-derived enzymes producing chiral aroma compounds and summarize the potential use of plants containing enzymes producing chiral aroma compounds for producing chiral flavors/fragrances.

Effect of cooking processes on tilapia aroma and potential umami perception

Tilapia is a freshwater fish group with a sustainable prospect but suffers off-notes appearing during cooking processes.To promote pleasant odorants by thermal cooking processes,tilapia fillets were cooked in different ways(roasting,microwave-heating,boiling and steaming).Their aroma profiles were analysed with special focus on off-notes and umami-enhancing odorants by principal component analysis,and correlated with the heating time,colour,moisture and water activity by partial least squares regression analysis.Results showed that the“green”and“earthy”off-notes were highly correlated with the boiling process(excess of water,short heating time),while most of the umami-enhancing odorants had a high association with the roasting process(low water content,long heating time,better Maillard reaction).This study indicated that roasting is the most adapted cooking process promoting Maillard-derived aromas,umami-enhancing aromas and meanwhile,reducing off-notes.This research helps in understanding the off-note generation in tilapia and promoting desirable umami-enhancing odorants.

Complexation with pre-formed“empty”V-type starch for encapsulation of aroma compounds

Aroma compounds are low-molecular-weight organic volatile molecules and are broadly utilized in the food industry.However,due to their high volatility and evaporative losses during processing and storage,the stabilization of these volatile ingredients using encapsulation is a commonly investigated practice.Complexation of aroma compounds using starch inclusion complex could be a potential approach due to the hydrophobicity of the left-handed single helical structure.In the present study,we used starch of three different V-type structures,namely V,V,and V,to encapsulate six different aroma compounds,including1-decanol(DN),cis-3-hexen-1-ol(HN),4-allylanisole(AN),γ-decalactone(DA),trans-cinnamaldehyde(CA),and citral(CT).The formed inclusion complexes samples were characterized using complementary techniques,including X-ray diffraction(XRD)and differential scanning calorimetry(DSC).The results showed that upon complexation with aroma compounds,all V-subtypes retained their original crystalline structures.However,different trends of crystallinity were observed for each type of the prepared inclusion complexes.Additionally,among three V-type starches,V-type starch formed inclusion complexes with aroma compounds most efficiently and promoted the formation of FormⅡcomplex.This study suggested that the structure of aroma compounds and the type of V starch could both affect the complexation properties.

Rice Aroma: A Natural Gift Comes with Price and the Way Forward

Aromatic rice belongs to a small but important sub-group of rice,which is highly regarded for its excellent aroma and superior grain quality.Aromatic rice,especially Basmati-and Jasmine-type rice,is being traded at a high price in the local and global markets.Genetically,rice aroma is a phenotypical expression of spontaneous recessive mutations of the OsBadh2 gene(also known as fgr/badh2/osbadh2/os2AP gene).These mutations inhibit the flow ofγ-aminobutyraldehyde(GAB-ald)toγ-aminobutyric acid(GABA),and consequently,the accumulated GAB-ald is diverted to a potent flavour component 2-acetyl-1-pyrroline(2AP)by a non-enzymatic reaction with methylglyoxal.The natural incidence of non-functional osbadh2 mutation along with selection and nursing by the farmer from the ancient time makes rice aroma as a prominent natural gift.As GABA and methylglyoxal play significant roles in stress tolerance,and their biosynthesis is strictly regulated in rice plants,the accumulation of 2AP in aromatic rice depends on the interaction of various genetic and environmental factors,and its production may come at some costs of sacrificing tolerance.This review focused on some potential underlying genes in the 2AP and GABA biosynthesis pathways,and analyzed most aspects of aroma formation in rice,and summarized the molecular mechanism of aroma production together with its genetic and non-genetic influencing factors.The present review also stated approaches to produce high-quality aromatic rice via developing novel cultivars and with good agronomic knowledge-based practice.

A View of Ancient Aroma Culture through Museum‑Collected Aroma Utensils

Aroma fumigation is one of the traditional Chinese fumigating therapies.Moreover,the aroma culture is a combination of traditional Chinese medicine culture with Confucian and folk cultures.As historical marks,medical relics such as aroma utensils,herbs,and books can reflect the development and prosperity of aroma culture in history.

Effects of different color paper bags on aroma development of Kyoho grape berries

This study investigated the influence of red,green,blue,and white paper bags on the free volatile compound development of Kyoho grape berries from green to harvest.Seven functional groups of volatiles were identified during the development of Kyoho grape berries including esters,aldehydes,alcohols,terpenes,ketones,acids,and hydrocarbons.Esters and aldehydes were abundant in Kyoho grape berries,mainly represented by ethyl acetate,ethyl butyrate,and(E)-2-hexenal.They accumulated quickly after veraison and slightly decreased toward maturation.Red,green,blue,and white paper bags promoted the accumulation of esters and inhibited the accumulation of aldehydes,also inhibited the accumulation of alcohols,tepenes,ketones,and acids.Their effect from strong to weak was green,blue,red,and white paper bags.The expression profiles of genes in the lipoxygenase-hydroperoxide lyase(LOX-HPL) pathway were also analyzed and the results indicated that the regulation of red,green,blue,and white paper bags on aldehydes,alcohols,and esters volatile aromas was at transcriptional level.The results expanded our comprehension in grape aroma biosynthesis and berry bagging technique in table grape cultivation.

Tea aroma formation

Besides water,tea is one of the most popular beverages around the world.The chemical ingredients and biological activities of tea have been summarized recently.The current review summarizes tea aroma compounds and their formation in green,black,and oolong tea.The flavor of tea can be divided into two categories:taste(non-volatile compounds)and aroma(volatile compounds).All of these aroma molecules are generated from carotenoids,lipids,glycosides,etc.precursors,and also from Maillard reaction.In the current review,we focus on the formation mechanism of main aromas during the tea manufacturing process.©2015 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Co-Treatment of EFF and 1-MCP for Enhancing the Shelf-Life and Aroma Volatile Compounds of Oriental Sweet Melons(Cucumis melo var.makuwa Makino)

Compared to other melon types, oriental sweet melon （Cucumis melo var. makuwa Makino） is quite a different species with a shorter shelf-life due to its typical climacteric behavior and thin pericarp. The purpose of this experiment is to explore the effects of co- treatment of enhanced freshness formulation （EFF） and 1-methylcyclopropene （1-MCP） on physiological changes and the content of aroma volatile compounds introduced by them of two oriental sweet melon cultivars （Yumeiren and Tianbao） during storage. The melons were stored in incubators with temperature of 15~C and a relative humidity of 85% for 24 d during which fruit quality and related physiological index were measured. Compared to the control, both treatments delayed fruit weight loss rate and kept the fruit firmness, water content and soluble solids content. Ascorbate peroxidase （APX） and phenylalanine ammonia lyase （PAL） activities showed fluctuations in treated melons, while lipoxygenase （LOX） activity （P〈0.01） and malondialdehyde （MDA） content （P〈0.05） decreased compared to control. During the early stage of storage, alcohols and aldehydes were the main volatile compounds, and esters gradually increased during storage. Of all the esters, acetic esters were the main components, followed by oxalic acid esters and other esters. The total content of aroma volatile compounds, esters, alcohols and aldehydes of co-treated melons were all higher than those of 1-MCP treated and control melons. In addition, the aroma volatile peak of co-treated melons occurred later than that of 1-MCP treated and control melons. In summary, co-treatment of EFF and 1-MCP was more beneficial than 1-MCP treatment to delay ripening and senescence, maintain fruit quality, enhance shelf-life and improve levels of aroma volatile compounds.

Changes of Aroma Components in Hongdeng Sweet Cherry During Fruit Development

To study the changes of aroma components in sweet cherry during fruit development, the aroma components in sweet cherry fruit from the green stage, the color stage, the commercial stage, and the ripe stage were collected using head-space solid phase microextraction （HS-SPME）, and were analyzed using a gas chromatograph-mass spectrophotometer （GC- MS）. A total of 37 compounds were identified from the sample extracts. Aldehydes, alcohols, and esters were the major constituents. The aroma components behaved differently during the fruit developmental period. C6 aldehydes and aromatic aldehydes were the main aldehydes in the sweet cherry fruit. The contents of C6 aldehydes increased quickly to 84.16% in the color stage, then decreased as ripening proceeded, and then, the contents decreased to 59.20 and 55.58% at the commercial stage and the ripe stage, respectively. The aromatic aldehydes （benzaldehyde） increased as ripening proceeded, and the maximum was found at the ripe stage. Alcohols of sweet cherry fruit included C6 alcohols and aromatic alcohols. The content of （E）-2-hexen-l-ol increased as ripening proceeded. The maximum was found at the commercial stage; alcohol was only found at the ripe stage. Ester components included ethyl acetate, butanoic acid ethyl ester, hexanoic acid ethyl ester, which increased as the fruit ripened. Hexanal, （E）-2-hexenal, benzaldehyde, （E）-2-hexen-l-ol, ethyl acetate, and hexanoic acid ethyl ester were the characteristic aroma components of sweet cherry fruit. These aroma components started to form drastically at the color stage, and the main aroma was formed at the commercial stage, which then turned bad at the ripe stage because of the presence of alcohol. So the optimal harvest time of sweet cherry was at the commercial stage.

The chromosome-level quality genome provides insights into the evolution of the biosynthesis genes for aroma compounds of Osmanthus fragrans

Sweet osmanthus(Osmanthus fragrans)is a very popular ornamental tree species throughout Southeast Asia and USA particularly for its extremely fragrant aroma.We constructed a chromosome-level reference genome of O.fragrans to assist in studies of the evolution,genetic diversity,and molecular mechanism of aroma development.A total of over 118 Gb of polished reads was produced from HiSeq(45.1 Gb)and PacBio Sequel(73.35 Gb),giving 100×depth coverage for long reads.The combination of Illumina-short reads,PacBio-long reads,and Hi-C data produced the final chromosome quality genome of O.fragrans with a genome size of 727 Mb and a heterozygosity of 1.45%.The genome was annotated using de novo and homology comparison and further refined with transcriptome data.The genome of O.fragrans was predicted to have 45,542 genes,of which 95.68%were functionally annotated.Genome annotation found 49.35%as the repetitive sequences,with long terminal repeats(LTR)being the richest(28.94%).Genome evolution analysis indicated the evidence of whole-genome duplication 15 million years ago,which contributed to the current content of 45,242 genes.Metabolic analysis revealed that linalool,a monoterpene is the main aroma compound.Based on the genome and transcriptome,we further demonstrated the direct connection between terpene synthases(TPSs)and the rich aromatic molecules in O.fragrans.We identified three new flower-specific TPS genes,of which the expression coincided with the production of linalool.Our results suggest that the high number of TPS genes and the flower tissue-and stage-specific TPS genes expressions might drive the strong unique aroma production of O.fragrans.

Analysis of Volatile Compounds and Identification of Characteristic Aroma Components of <i>Toona sinensis</i>(A. Juss.) Roem. Using GC-MS and GC-O

In this study, volatile compounds present in Toona sinensis (A. Juss.) Roem (TS) were investigated and their characteristic aromatic components were identified using Headspace Solid-phase Microextraction (HS-SPME) followed by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Olfactometry (GC-O). The optimum conditions for extracting the volatiles from TS were achieved with the experimental parameters including the use of a 65 μm polydimethylsiloxane/divinyl benzene (PDMS/DVB) fibre, an extraction temperature of 40℃ and an extraction time of 30 min. Under these conditions, 56 volatile compounds were separated and 53 were identified by GC-MS. Among them, 21 sulfide compounds (42.146%) and 27 terpenes(55.984%) were found to be the major components. The sample was analyzed by GC-O and 26 elutes were sniffed and their sensory descriptions evaluated by an odor panelists. Analysis of the data indicated, two compounds cis and trans isomers of 2-Mercapto-3,4-dimethyl-2,3-dihydrothiophene were major contributors to the characteristic aroma of TS.

Quality Characteristics of Tobacco Leaves with Different Aromatic Styles from Guizhou Province,China

The relationships between chemical components and quality indexes were studied in the tobacco leaves with different aromatic styles. A total of 16 chemical components, 4 quality indexes, and 6 smoking quality indexes from 366 tobacco leaf samples with 4 different types of aroma from Guizhou Province, China, were subjected to principal component analysis and stepwise regression analysis. The tobacco leaves with different types of aroma showed remarkable difference in the contents of chemical components, quality indexes, and smoking quality indexes. The first principal factors （carbohydrates and nitrogen-containing compounds） of the chemical composition of the leaf were similar among different types of aroma, which showed that the quality of the leaf was mainly influenced by carbohydrates and nitrogen-containing compounds and their ratios. The factors for the second through the seventh principal components varied largely among varioUs aromatic types, suggesting the contribution of other chemical components to the leaf quality. In addition, the smoking quality of four different aromatic leaves showed significant correlation with the different chemical components. The quality of tobacco leaves with different types of aroma was influenced by multiple factors, especially ecological conditions and culture techniques, which may provide guidance for directive cultivation of high-quality tobacco leaves.

Impact of a Non-<i>Saccharomyces</i>Yeast Isolated in the Equatorial Region in the Acceptance of Wine Aroma

The aim of this work was to isolate and identify the yeasts prevalent in fresh grapes cultivated in the “S&atilde;o Francisco Valley” region (Brazil), as well as evaluating the cell growth of these indigenous yeasts during the fermentation of grape musts and their contribution to the improvement of wine aroma. The Chenin Blanc grape must fermented by H. opuntiae presented higher acceptance means at the three points analyzed (6.74, 6.78 and 7.30) and in the fermentation carried out by the yeasts H. opuntiae and S. cerevisiae, the highest mean acceptance (7.22) was observed after 120 hours, with no statistical difference from the sample fermented by H. opuntiae alone. Since these samples that showed higher acceptance means also receiving higher scores for purchasing intention, corresponding to the concepts of “definitely would buy” and “probably would buy”. The present study suggests that the fermentations of grape musts carried out by the yeast H. opuntiae and mixed cultures of H. opuntiae and Saccharomyces cerevisiae, positively influenced the sensory qualities of the wines and showed greater potential to increase the aroma of the musts and to develop specific wine styles.

Differences of aroma development and metabolic pathway gene expression between Kyoho and 87-1 grapes

Aroma is an important quality trait of grapes and often the focus of consumers,viticulturists and grapevine breeders.Kyoho is a hybrid between Vitis vinifera and Vitis labrusca with a strawberry-like scent,while 87-1 is an early-ripening mutant of Muscat hamburg,belonging to Vitis vinifera,with a rose scent.In this study,we compared their aroma compositions and concentrations during berry development by headspace-SPME combined with gas chromatography-mass spectrometry(GC-MS),and analyzed the expression differences of enzyme-encoding genes in the LOX-HPL,MEP and MVA metabolic pathways by qRT-PCR.Twelve esters were detected in Kyoho during the whole berry development and they were abundant after veraison,but no esters were detected in 87-1 berries.Linalool was the dominant terpene among the 14 terpenes detected in 87-1 berries,while limited amounts of terpenes were detected in Kyoho berries.qRT-PCR analysis indicated that the low expression of VvAAT might explain the low content of ester volatiles in 87-1 berries,and the low expression of coding genes in the MEP pathway,especially VvPNLin Ner1,might be the reason for the low content of volatile terpenes in Kyoho berries.The results from this work will promote our understanding of aroma metabolic mechanisms of grapes,and offer some suggestions for grape aromatic quality improvement.

Study on Aroma Components in Fruit From Three Different Satsuma Mandarin Varieties

Fruit aroma of Guoqing 1, Miyagawa Wase, and Owari from three different Satsuma mandarin varieties were investigated by headspace solid phase microextraction （HS-SPME） combined with GC-MS. The results showed that there were 73, 71, and 66 aroma components in the three varieties, and the total contents were 584.67,505.29, and 494.63 μg g^-1, respectively. Total 29 constituents were common in the three varieties. It was also found that Guoqing 1, Miyagawa Wase, and Owari had 12, 5, and 2 unique components, respectively. The key aroma components were limonene, linalool, γ-terpinene, β- myrcene, α-pinene, and octanal in the three fruits. Guoqing 1 contained more key aroma compounds than Miyagawa Wase and Owari.

The genetic basis of grape and wine aroma

The grape is one of the oldest and most important horticultural crops.Grape and wine aroma has long been of cultural and scientific interest.The diverse compound classes comprising aroma result from multiple biosynthetic pathways.Only fairly recently have researchers begun to elucidate the genetic mechanisms behind the biosynthesis and metabolism of grape volatile compounds.This review summarizes current findings regarding the genetic bases of grape and wine aroma with an aim towards highlighting areas in need of further study.From the literature,we compiled a list of functionally characterized genes involved in berry aroma biosynthesis and present them with their corresponding annotation in the grape reference genome.

Population Structure and Marker-Trait Association in Indigenous Aromatic Rice

Joha rice of Assam is a class of rice with aroma, good cooking qualities and excellent palatability, which are grown in different places of Assam with their adaptability to local situations. A total of 143 simple sequence repeat markers were used in this study to reveal sufficient genetic variations among the 40 Joha and 14 non-Joha rice genotypes. Polymorphism information content of these markers were from 0.17 to 0.88, where the average of 3.7 alleles were observed. The model-based population assignment and dendrogram analysis identified three distinct groups in the 54 rice accessions, which established a clear identity of Joha accessions from the Basmati accessions, indicating high diversity and strong population structure in Joha rice. Furthermore, a total of 29 significant marker-trait associations(P < 0.05) for 10 characters were detected. The QTLs related with yield and grain quality can be used effectively in crop improvement programs and for further fine mapping and validation of specific genes to develop gene-based perfect markers in rice breeding and for mining of better alleles of these genes in Joha rice collections.

A key‘foxy’aroma gene is regulated by homologyinduced promoter indels in the iconic juice grape‘Concord’

‘Concord’,the most well-known juice grape with a parentage of the North American grape species Vitis labrusca L.,possesses a special‘foxy’aroma predominantly resulted from the accumulation of methyl anthranilate(MA)in berries.This aroma,however,is often perceived as an undesirable attribute by wine consumers and rarely noticeable in the common table and wine grape species V.vinifera.Here we discovered homology-induced promoter indels as a major genetic mechanism for species-specific regulation of a key‘foxy’aroma gene,anthraniloyl-CoA:methanol acyltransferase(AMAT),that is responsible for MA biosynthesis.We found the absence of a 426-bp and/or a 42-bp sequence in AMAT promoters highly associated with high levels of AMAT expression and MA accumulation in‘Concord’and other V.labrusca-derived grapes.These promoter variants,all with direct and inverted repeats,were further confirmed in more than 1,300 Vitis germplasm.Moreover,functional impact of these indels was validated in transgenic Arabidopsis.Superimposed on the promoter regulation,large structural changes including exonic insertion of a retrotransposon were present at the AMAT locus in some V.vinifera grapes.Elucidation of the AMAT genetic regulation advances our understanding of the‘foxy’aroma trait and makes it genetically trackable and amenable in grapevine breeding.

Predominant yeasts in Chinese Dong fermented pork(Nanx Wudl)and their aroma-producing properties in fermented sausage condition

Yeasts are one of the predominant microbial groups in fermented meats.In this study,yeast communities of Chinese Dong fermented pork(Nanx Wudl)were investigated and the technological properties of 73 yeast isolates were evaluated.Through culture-dependent and high-throughput sequencing methods,the main yeast species identified included Pichia membranifaciens,Kazachstania bulderi,Millerozyma farinosa,Candida zeylanoides,Kazachstania exigua,Candida parapsilosis and Saccharomyces cerevisiae.Among these yeasts,P.membranifaciens,M.farinosa,K.exigua and K.bulderi were detected in fermented meats for the first time.A total of 73 yeast isolates was investigated for their lipolytic and proteolytic activities.All yeast species showed lipolytic activity,while proteolytic activity against meat protein was only detected in S.cerevisiae.Assay of aroma-producing potential was performed in a model simulating fermented sausage condition.Inoculation of yeast strains increased volatiles production,especially esters and alcohols.The highest ester production was observed in S.cerevisiae Y70 strain,followed by K.exigua Y12 and K.bulderi Y19.C.zeylanoides Y10 and S.cerevisiae Y70 were the highest producers of benzeneethanol and 3-methyl-1-butanol.S.cerevisiae Y70 with its highest production of branched alcohols and esters could be a promising candidate as aroma enhancer in the manufacture of fermented sausages.