Determination of compounds responsible for tempeh aroma

Sodium content of plant-based meat and cheese analogues: comparison with benchmarks proposed by the World Health Organization

Although plant-based analogues of animal products have become increasingly common, their sodium content has not been adequately investigated. The main aims of this study were to: (i) compare sodium content of cheese analogues, meat analogues, and tofu and tempeh sold in Italy with the relative WHO benchmarks (720, 250 and 280 mg/100 g, respectively); and (ii) evaluate the effectiveness of Nutri-Score in identifying products exceeding these benchmarks. Food labels from 430 meat analogues, 49 cheese analogues and 42 tofu and tempeh products were collected and analysed. Meat analogues (93%) and tofu and tempeh (57%) had the highest percentage of products exceeding the benchmark while cheese analogues had the lowest (20%). All subcategories in the meat analogues category showed a higher median sodium content than the benchmark, with cured meats having the highest level. Among cheese analogues, the grated cheese subcategory showed the highest median sodium content with all products exceeding the benchmark, while tofu and tempeh had the lowest median sodium content. The Nutri-Score algorithm did not consistently identify products with sodium levels exceeding the established benchmarks. This study highlights the need to reduce sodium content of such products and emphasises the importance of improving consumers' nutritional awareness.

Insights from traditional fermented legumes towards the innovation of modern plant-based meat analogues

There has been a major growth in the development of plant-based meat alternatives (PBMA) in recent years. However, current PBMA often contain ultra processed ingredients and numerous additives to be able to mimic animal-based meat (ABM) including the meaty (umami) flavour, characteristic firm/chewy structure and juicy mouthfeel. In this review, the potential of ancient fermentation techniques as a minimally processed alternative to ABM and current PBMA are explored. Fermented foods including tempeh, natto, dawadawa and ugba are naturally high in protein and umami flavours. The nutritional, aroma, flavour and techno-functional properties are provided and discussed in the context of ABM and PBMA. The fermented foods have potential to be used as whole foods ingredients, or their constituents can be used as ingredients in plant-based foods. Particularly the umami flavours and high protein content combined with the naturally occurring high water holding capacity (WHC), solubility and other material properties make fermented legume foods suitable candidates for use in high-protein plant-based foods. Understanding the sensory characteristics and material properties generated during legume fermentation and their similarities to ABM can aid in stimulating innovations in food technology to obtain a new generation of less-processed PBMA with limited additives.

Sensory and volatile compound profiles in tempeh-like products from faba bean and oats

Faba beans (Vicia faba L.) and whole-grain oats (Avena sativa L.) offer a high protein content, are a source of dietary fibre and they can be sustainably produced in the Nordic countries, yet face sensory limitations that restrict their wider use in food. This study aimed to overcome these sensory limitations by soaking the faba bean and whole-grain oats with Lactiplantibacillus plantarum, followed by solid-state fermentation with Rhizopus microsporus to produce tempeh-like products. Volatile organic compounds in uncooked and cooked tempeh were analysed using Headspace Solid-Phase Micro-Extraction (HS-SPME) with Gas Chromatography-Mass Spectrometry (GC-MS). Sensory profiling was combined with texture and moisture measurements from uncooked and cooked tempeh-like products to explore sensory and physicochemical attributes. A hedonic test evaluated overall acceptability of the selected samples. A total of 65 volatile organic compounds were identified and semi-quantified, including 3-methyl-1-butanol, ethanol, 2-butanone, acetic acid, and acetoin. L. plantarum soaking reduced certain volatile organic compounds typically associated with beany off-flavours, while cooking increased certain compounds such as acids and pyrazines, potentially masking off-flavours. The soaking resulted in increased sourness, umami taste, and chewiness, with notable texture variation when whole-grain oats were included compared to only faba bean tempeh. Texture measurements were significantly influenced by L. plantarum soaking, as shown by the panellist. Hedonic testing (n = 107) indicated a higher degree of liking for tempeh made from the faba beans and whole-grain oats mix compared to only faba bean tempeh. These findings emphasise the need to assess how pre-treatments, such as soaking, impact on tempeh-like production.

Integrative metabolomics - GC-IMS approach to assess metabolic and flavour substance shifts during fermentation of Yangjiang douchi

Douchi is traditional Chinese condiment. In this study, electronic sense, GC-IMS and metabolomics were combined to analyse the changes in flavour profiles and metabolites of Yangjiang douchi at different fermentation stages. The results showed that umami was the primary taste characteristic of douchi. Aldehydes, esters, and ketones representing the predominant flavour compounds. Metabolomic analysis identified 13 compounds as key differential metabolites, which were mainly enriched in the arachidonic acid metabolic pathway in lipid metabolism. The correlation analysis indicated that heptanal, hexanal, phenyl acetaldehyde, benzene acetaldehyde and abhexone may be the key aroma substances during fermentation. The major free fatty acids that may act as key flavour precursors are palmitic acid, oleic acid and linoleic acid. This study provides a scientific basis for the industrial regulation of Yangjiang douchi fermentation.

The Potential Correlation between Bacterial Diversity and the Characteristic Volatile Flavor Compounds of Sichuan Sauce-Flavored Sausage

The distinctive taste of Sichuan sauce-flavored sausage comes from an intricate microbial metabolism. The correlation between microbial composition and distinct flavor components has not been researched. The study used headspace solid-phase microextraction action with gas chromatography mass spectrometry to find flavor components and high-throughput sequencing of 16S rRNA to look at the diversity and succession of microbial communities. The correlation network model forecasted the connection between essential bacteria and the development of flavors. The study revealed that the primary flavor compounds in Sichuan sauce-flavored sausages were alcohols, aldehydes, and esters. The closely related microbes were Leuconostoc, Pseudomonas, Psychrobacter, Flavobacterium, and Algoriella. The microbes aided in the production of various flavor compounds, such as 1-octen-3-ol, benzeneacetaldehyde, hexanal, (R,R)-2,3-butanediol, and ethyl caprylate. This work has enhanced our comprehension of the diverse functions that bacteria serve in flavor development during the fermentation of Sichuan sauce-flavored sausage.

Microbiology of fermented soy foods in Asia: Can we learn lessons for production of plant cheese analogues?

The food industry is facing the challenge of creating innovative, nutritious, and flavored plant-based products, due to consumer's increasing demand for the health and environmental sustainability. Fermentation as a unique and effective tool plays an important role in the innovation of food products. Traditional fermented soy foods are popular in many Asian and African countries as nutritious, digestible and flavorful daily staples or condiments. They are produced by specific microorganisms with the unique fermentation process in which microorganisms convert the ingredients of whole soybean or soybean curd to flavorful and functional molecules. This review provides an overview on traditional fermented food produced from soy, including douchi, natto, tempeh, and sufu as well as stinky tofu, including the background of these products, the manufacturing process, and the microbial diversity involved in fermentation procedures as well as flavor volatiles that were identified in the final products. The contribution of microbes to the quality of these five fermented soy foods is discussed, with the comparison to the role of cheese ripening microorganisms in cheese flavor formation. This communication aims to summarize the microbiology of fermented soy foods in Asia, evoking innovative ideas for the development of new plant-based fermented foods especially plant-based cheese analogues.

Unraveling the contribution of aroma-active and chiral compounds to different grade of Yashi Xiang teas using stir bar sorptive extraction

Yashi Xiang (YSX) is a flavor of Fenghuang Dancong tea and famous for its name and floral aroma, which is a type of semi-fermented oolong tea. However, previous research into the aroma characteristics of YSX tea mostly focused on the aroma compounds, and little research on chiral compounds in YSX has been performed. Therefore, the current study was conducted to explore the aroma characteristics of YSX tea from the perspective of enantiomers of chiral compounds. A total of 12 enantiomers were determined in this study, among them, (R)-(-)-α-ionone, (S)-(+)-linalool, (1S,2S)-(+)-methyl jasmonate, (S)-z-nerolidol, (R)-(+)-limonene, and (S)-(-)-limonene have important effects on the aroma components of YSX tea. The ER ratios of the enantiomers were different in samples of different grades. Therefore, this parameter can be used to identify the grade and authenticity of YSX tea. PRACTICAL APPLICATION: The study illuminates the aroma characteristics of YSX tea from the perspective of enantiomers of chiral compounds, which have important effects on the aroma components of YSX tea. It established an ER ratio system to effectively distinguish the grade and authenticity of YSX tea by comparing the ER of YSX tea. Focusing on analyzing the chiral compounds in the aroma of YSX tea is helpful in providing a theoretical basis for the authenticity of the precious tea and improving of the quality of YSX tea products.

Safety evaluation and application of lactic acid bacteria and yeast strains isolated from Sichuan broad bean paste

Broad bean paste is one of the most popular characteristic traditional fermented bean products in China, which is prepared by mixed fermentation of a variety of microorganisms, among which lactic acid bacteria and yeast played an important role in the improvement of the fermented broad bean paste quality. However, the traditional open-air fermentation of broad bean paste brought some risks of harmful microorganisms. In this study, the safety and fermentation ability of lactic acid bacteria and yeast strains isolated from traditional broad bean paste was evaluated. The results showed that the protease activity of the strain Lactobacillus plantarum DPUL-J5 (366.73 ± 9.00 U/L) and Pichia kudriavzevii DPUY-J5 (237.18 ± 10.93 U/L) were the highest. Both strains produced little biogenic amines, and did not exhibit α-hemolytic activity or antibiotic resistance for some of the antibiotics most used in human medicine. Furthermore, the broad bean paste fermentation involving DPUL-J5 and DPUY-J5 was beneficial for accumulating higher total acid (1.69 ± 0.01 g/100 g), amino-acid nitrogen (0.85 ± 0.03 g/100 g), and more volatile flavor compounds, meanwhile, reducing the levels of biogenic amines and aflatoxin B1. Therefore, this study provided a new strategy to improve the safety and quality of traditional broad bean paste.

Role of Sulfur Compounds in Vegetable and Mushroom Aroma

At the base of the food pyramid is vegetables, which should be consumed most often of all food products, especially in raw and unprocessed form. Vegetables and mushrooms are rich sources of bioactive compounds that can fulfill various functions in plants, starting from protection against herbivores and being natural insecticides to pro-health functions in human nutrition. Many of these compounds contain sulfur in their structure. From the point of view of food producers, it is extremely important to know that some of them have flavor properties. Volatile sulfur compounds are often potent odorants, and in many vegetables, belonging mainly to Brassicaeae and Allium (Amaryllidaceae), sulfur compounds determine their specific flavor. Interestingly, some of the pathways that form volatile sulfur compounds in vegetables are also found in selected edible mushrooms. The most important odor-active organosulfur compounds can be divided into isothiocyanates, nitriles, epithionitriles, thiols, sulfides, and polysulfides, as well as others, such as sulfur containing carbonyl compounds and esters, R-L-cysteine sulfoxides, and finally heterocyclic sulfur compounds found in shiitake mushrooms or truffles. This review paper summarizes their precursors and biosynthesis, as well as their sensory properties and changes in selected technological processes.

Characteristic fingerprints and volatile flavor compound variations in Liuyang Douchi during fermentation via HS-GC-IMS and HS-SPME-GC-MS

The present study investigates volatile organic compound (VOC) compositional changes in Liuyang Douchi during fermentation via a HS-GC-IMS and HS-SPME-GC-MS combination approach. A total of 115 VOCs were identified from Douchi, most of which were accumulated during pile fermentation. Notably, most alcohols and acids decreased with fermentation, while esters, ketones, pyrazines, and phenols accumulated during pile fermentation. Depending on the VOCs identified by GC-IMS/MS, the different fermentation stages of Douchi could be facilely distinguished. Of these, 49 VOCs were regarded as the marker VOCs of Douchi in different fermentation stage: hexanol, hexanal, and propanoic acid was the marker VOCs of the black beans before fermentation and contributing beany and grassy odors; 1-octen-3-ol and 3-octanone supplying a mushroom aroma to the Douchi fermented for 3-9 days; and esters and pyrazine, especially ethyl acetate and 2,6-dimethylpyrazine, contributing the cocoa, fruity, and nutty aromas of matured Douchi.

Fermented meat sausages and the challenge of their plant-based alternatives: A comparative review on aroma-related aspects

Traditional fermented meat sausages are produced around the world due to their convenience and sensory characteristics which are responsible for their high acceptability. They constitute a cultural heritage as shown by the high diversity of products around the world. Recent trends are addressing issues regarding innovation in their formulation by reduction of salt, fat and additives (curing salts). However, the current trend towards a reduction in the consumption of meat has produced an increase in the formulation of meat product analogues. This trend is the main focus of producers to offer new attractive products to consumers even though the aroma profile of traditional fermented meat sausages is not reached. In this manuscript, we review and discuss the chemistry of aroma formation in traditional fermented meat sausages in contrast to the potential of plant-based ingredients used in meat analogues.

Characterization of the Key Aroma-Active Compounds in Yongchuan Douchi (Fermented Soybean) by Application of the Sensomics Approach

Yongchuan douchi is a traditional fermented soya bean product which is popular in Chinese dishes due to its unique flavor. In this study, the key aroma-active compounds of Yongchuan douchi were characterized by the combined gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS) with sensory evaluation. In total, 49 aroma compounds were sniffed and identified, and 20 of them with high flavor dilution factors (FD) and odor activity values (OAVs) greater than one were screened by applied aroma extract dilution analysis (AEDA) and quantitated analysis. Finally, aroma recombination and omission experiments were performed and 10 aroma-active compounds were thought to have contributed significantly including 2,3-butanedione (butter, cheese), dimethyl trisulfide (garlic-like), acetic acid (pungent sour), acetylpyrazine (popcorn-like), 3-methylvaleric acid (sweaty), 4-methylvaleric acid (sweaty), 2-mehoxyphenol (smoky), maltol (caramel), γ-nonanolactone (coconut-like), eugenol (woody) and phenylacetic acid (flora). In addition, sensory evaluation showed that the flavor profile of Yongchuan douchi mainly consisted of sauce-like, sour, nutty, smoky, caramel and fruity notes.

Membrane-based preparative methods and bioactivities mapping of tempe-based peptides

This study was aimed to produce bioactive peptides from optimally fermented tempe, and map their overall bioactivities. There were three preparative methods utilized for producing tempe-based peptides, such as water-facilitated extraction, alcalase, and papain hydrolysis, and in combination with membrane filtration. Fermenting soybean at 144 h was selected as the optimum time based on protein content and degree of hydrolysis. Through SDS-PAGE analysis, an increased degree of hydrolysis with longer fermentation time was confirmed. The best preparative method for producing bioactive peptides was through papain hydrolysis and followed by 5 kDa membrane filtration. By this, the enhancement was distinct for antioxidant activity, ACE-, α-glucosidase-, and Kunitz trypsin-inhibitory activity. The annotated peptide sequences resulting from Nano LC Ultimate 3000 Series System tandem Q Exactive™ Hybrid Quadrupole-Orbitrap™ Mass Spectrometer were matched with the BIOPEP database. The major bioactivities of tempe peptides obtained were as an ACE inhibitor, antioxidant, and antithrombotic.

Characterization of Key Aroma Compounds in Raw and Roasted Peas (Pisum sativum L.) by Application of Instrumental and Sensory Techniques

Gas chromatography-olfactometry (GC-O) coupled with GC-mass spectrometry (GC-MS) and aroma recombination-omission experiments led to the identification of the key aroma compounds responsible for the different flavors of raw and roasted peas. The results demonstrated that a total of 30 odorants were identified in raw and roasted peas. Nine and twenty compounds were identified as important odorants in raw and roasted peas with odor activity values (OAVs) greater than 1, respectively. Aroma recombination-omission experiments demonstrated that six aroma compounds significantly contributed to the characteristic aroma of peas (p < 0.05). Among these, 3-methylbutanoic acid (OAV = 382) and hexanal (OAV = 280) significantly contributed to the aroma of peas. Fifteen aroma compounds significantly contributed to the characteristic aroma of roasted peas (p < 0.05). Among these, pyrazines and pyranones showed important contribution to the aroma of roasted peas. Roasting increased the variety of key aroma compounds significantly and contributed a nutty flavor to peas. The comprehensive aroma characterization of peas and determination of the effect of roasting on key aroma compound alteration will be helpful for new pea products' flavor quality control.

Antioxidant Activity, Total Polyphenol, Flavonoid and Tannin Contents of Fermented Green Coffee Beans with Selected Yeasts

We examined the antioxidant activity, total polyphenol content (TPC), total flavonoid content (TFC), total tannin content (TTC) and physical characteristics of green coffee beans fermented with selected yeasts. There was no significant (p > 0.05) interaction effect between yeast-fermented coffee extracts and duration of fermentation on antioxidant activity (oxygen radical absorbance capacity [ORAC] and superoxide dismutase-like [SOD-like] activity). However, the mean of the antioxidant activity (ORAC and SOD-like activity) significantly (p < 0.05) increased in the fermented coffee extracts compared to unfermented coffee. There were significant (p < 0.05) interaction effects between yeast-fermented coffee extracts and duration of fermentation (24 h and 48 h) on the TPC, TFC, TTC and pH of the fermented solution and on the colors of the ground-roasted coffee. The TPC showed a pattern of increase in samples Ferm-1 and Ferm-3 as fermentation time increased from 24 h to 48 h. However, a decreasing TPC trend was observed in Ferm-2 as the number of fermentation hours increased from 24 to 48. The fermented coffee beans had a significantly higher flavonoid content than the unfermented coffee beans, while fermentation significantly decreased the tannin content compared to that in unfermented coffee.

Aroma Profile Analyses of Filamentous Fungi Cultivated on Solid Substrates

Filamentous fungi have been used since centuries in the production of food by means of solid substrate fermentation (SSF). The most applied SSF involving fungi is the cultivation of mushrooms, e.g., on tree stumps or sawdust, for human consumption. However, filamentous fungi are also key players during manufacturing of several processed foods, like mold cheese, tempeh, soy sauce, and sake. In addition to their nutritive values, these foods are widely consumed due to their pleasant flavors. Based on the potentials of filamentous fungi to grow on solid substrates and to produce valuable aroma compounds, in recent decades, several studies concentrated on the production of aroma compounds with SSF, turning cheap agricultural wastes into valuable flavors. In this review, we focus on the presentation of common analytical methods for volatile substances and highlight various applications of SSF of filamentous fungi dealing with the production of aroma compounds. Graphical Abstract.

Effects of Tempeh Fermentation with Lactobacillus plantarum and Rhizopus oligosporus on Streptozotocin-Induced Type II Diabetes Mellitus in Rats

The increased consumption of high fat-containing foods has been linked to the prevalence of obesity and abnormal metabolic syndromes. Rhizopus oligosporus, a fungus in the family Mucoraceae, is widely used as a starter for homemade tempeh. Although R. oligosporus can prevent the growth of other microorganisms, it grows well with lactic acid bacteria (LAB). Lactobacillus plantarum can produce β-glucosidase, which catalyzes the hydrolysis of glucoside isoflavones into aglycones (with greater bioavailability). Therefore, the development of a soybean-based functional food by the co-inoculation of R. oligosporus and L. plantarum is a promising approach to increase the bioactivity of tempeh. In this study, the ameliorative effect of L. plantarum in soy tempeh on abnormal carbohydrate metabolism in high-fat diet (HFD)-induced hyperglycemic rats was evaluated. The co-incubation of L. plantarum with R. oligosporus during soy tempeh fermentation reduced the homeostatic model assessment of insulin resistance, HbA1c, serum glucose, total cholesterol, triglyceride, free fatty acid, insulin, and low-density lipoprotein contents, and significantly increased the high-density lipoprotein content in HFD rats. It also increased the LAB counts, as well as the bile acid, cholesterol, triglyceride, and short-chain fatty acid contents in the feces of HFD rats. Our results suggested that the modulation of serum glucose and lipid levels by LAB occurs via alterations in the internal microbiota, leading to the inhibition of cholesterol synthesis and promotion of lipolysis. Tempeh, which was produced with both L. plantarum and R. oligosporus, might be a beneficial dietary supplement for individuals with abnormal carbohydrate metabolism.

Source-water odor during winter in the Yellow River area of China: Occurrence and diagnosis

Yellow River source water has long suffered from odor problems in winter. In this study, odor characteristics, potential odorants, and algae in the source water of six cities (Lanzhou, Yinchuan, Hohhot, Zhengzhou, Jinan and Dongying) along the Yellow River were determined in winter (February to March 2014). According to flavor profile analysis (FPA), moderate to strong fishy odors occurred in all cities, except for Lanzhou. At the same time, mild earthy/musty odors and septic/swampy odors were also detected. The strong fishy odor (FPA intensity, 8.5) in Yinchuan was attributed to the abnormal growth of Dinobryon (cell density, 5.7 × 10⁴ cells/mL), while the fishy odors in Hohhot, Zhengzhou, Jinan, and Dongying might be caused by Melosira and Cyclotella, Cryptomonas, Dinobryon, and Synedra, respectively. Unsaturated aldehydes, which have been reported to cause fishy odors, were not detected in all samples. However, some saturated aldehydes, including hexanal, heptanal, nonanal, decanal, and benzaldehyde, were detected with a total concentration range of 690 ng/L to 2166 ng/L, and might have partly contributed to the fishy odors. In addition, 2-MIB (5.77-21.12 ng/L) and geosmin (2.26-9.73 ng/L) were responsible for the earthy/musty odors in the Yellow River source waters, and dimethyl disulfide (648.2 ng/L) was responsible for the rancid/swampy odor (FPA intensity, 8.0) episode in Yinchuan. This is a comprehensive study reporting on the occurrence and possible reasons for the odor issues in the Yellow River source water during winter.

Dimethyl trisulfide: A novel cyanide countermeasure

In the present studies, the in vitro and in vivo efficacies of a novel cyanide countermeasure, dimethyl trisulfide (DMTS), were evaluated. DMTS is a sulfur-based molecule found in garlic, onion, broccoli, and similar plants. DMTS was studied for effectiveness as a sulfur donor-type cyanide countermeasure. The sulfur donor reactivity of DMTS was determined by measuring the rate of the formation of the cyanide metabolite thiocyanate. In experiments carried out in vitro in the presence of the sulfurtransferase rhodanese (Rh) and at the experimental pH of 7.4, DMTS was observed to convert cyanide to thiocyanate with greater than 40 times higher efficacy than does thiosulfate, the sulfur donor component of the US Food and Drug Administration-approved cyanide countermeasure Nithiodote^® In the absence of Rh, DMTS was observed to be almost 80 times more efficient than sodium thiosulfate in vitro The fact that DMTS converts cyanide to thiocyanate more efficiently than does thiosulfate both with and without Rh makes it a promising sulfur donor-type cyanide antidote (scavenger) with reduced enzyme dependence in vitro The therapeutic cyanide antidotal efficacies for DMTS versus sodium thiosulfate were measured following intramuscular administration in a mouse model and expressed as antidotal potency ratios (APR = LD₅₀ of cyanide with antidote/LD₅₀ of cyanide without antidote). A dose of 100 mg/kg sodium thiosulfate given intramuscularly showed only slight therapeutic protection (APR = 1.1), whereas the antidotal protection from DMTS given intramuscularly at the same dose was substantial (APR = 3.3). Based on these data, DMTS will be studied further as a promising next-generation countermeasure for cyanide intoxication.

Comparison of Aroma-Active Volatiles in Oolong Tea Infusions Using GC-Olfactometry, GC-FPD, and GC-MS

The aroma profile of oolong tea infusions (Dongdingwulong, DDWL; Tieguanyin, TGY; Dahongpao, DHP) were investigated in this study. Gas chromatography-olfactometry (GC-O) with the method of aroma intensity (AI) was employed to investigate the aroma-active compounds in tea infusions. The results presented forty-three, forty-five, and forty-eight aroma-active compounds in the TGY, DHP, and DDWL infusions, including six, seven, and five sulfur compounds, respectively. In addition, the concentration of volatile compounds in the tea infusions was further quantitated by solid phase microextraction-gas chromatography (SPME)-GC-MS and SPME-GC-flame photometric detection (FPD). Totally, seventy-six and thirteen volatile and sulfur compounds were detected in three types of tea infusions, respectively. Quantitative results showed that forty-seven aroma compounds were at concentrations higher than their corresponding odor thresholds. On the basis of the odor activity values (OAVs), 2-methylpropanal (OAV: 230-455), 3-methylbutanal (1-353), 2-methylbutanal (34-68), nerolidol (108-184), (E)-2-heptenal (148-294), hexanal (134-230), octanal (28-131), β-damascenone (29-59), indole (96-138), 6-methyl-5-hepten-2-one (34-67), (R)-(-)-linalool (63-87), and dimethyl sulfide (7-1320) presented relatively higher OAVs than those of other compounds, indicating the importance of these compounds in the overall aroma of tea infusions.

Evolution of Volatile Flavour Compounds during Fermentation of African Oil Bean (Pentaclethra macrophylla Benth) Seeds for "Ugba" Production

Fermented African oil bean (Pentaclethra macrophylla Benth) seed is a successful and well studied seasoning and snack in parts of Western Africa. GC-MS analysis of fermenting seeds revealed a mixture of several volatile aroma compounds which changed with time and starter organism. During natural mixed culture process 36 volatile compounds including 12 hydrocarbons, 10 esters, 5 alcohols, 2 phenols, 2 ketones, and one each of furan, amine, acid, thiophene, and lactone were identified. When Bacillus subtilis was used in pure culture, 30 compounds comprising 10 hydrocarbons, 8 esters, 3 alcohols, 2 amines, 2 sulfur compounds, and one of each of acid, aldehyde, phenol, ketone, and furan were identified. Sample fermented with B. megaterium produced 29 aroma compounds comprising 9 hydrocarbons, 10 esters, 2 nitrogenous compounds, 2 ketones, 3 alcohols, and one of each of lactone, aldehyde, furan, and amine. Methyl esters of various long chain fatty acids may be key aroma compounds, based on consistency and persistence. Qualitative or quantitative contribution of individual compounds may only be determined following flavour threshold analysis.

Gas chromatography analysis with olfactometric detection (GC-O) as a useful methodology for chemical characterization of odorous compounds

The gas chromatography-olfactometry (GC-O) technique couples traditional gas chromatographic analysis with sensory detection in order to study complex mixtures of odorous substances and to identify odor active compounds. The GC-O technique is already widely used for the evaluation of food aromas and its application in environmental fields is increasing, thus moving the odor emission assessment from the solely olfactometric evaluations to the characterization of the volatile components responsible for odor nuisance. The aim of this paper is to describe the state of the art of gas chromatography-olfactometry methodology, considering the different approaches regarding the operational conditions and the different methods for evaluating the olfactometric detection of odor compounds. The potentials of GC-O are described highlighting the improvements in this methodology relative to other conventional approaches used for odor detection, such as sensoristic, sensorial and the traditional gas chromatographic methods. The paper also provides an examination of the different fields of application of the GC-O, principally related to fragrances and food aromas, odor nuisance produced by anthropic activities and odorous compounds emitted by materials and medical applications.