Characteristics of kopyor coconut (Cocos nucifera L.) using sensory analysis and metabolomics-based approach.

Kopyor is a coconut with unique characteristics from Indonesia, one of the largest coconut producers in the world. Kopyor is an edible mature coconut with soft endosperm. Although this fruit is one of the most popular coconuts in the world, there are limited studies on its properties, including its sensory attributes and metabolite profiles. This study investigates the characteristics of kopyor using sensory evaluation, a widely targeted metabolomics approach, and multivariate analysis. The liquid (water) and solid (flesh) endosperms were collected as the samples. The results showed that kopyor has characteristics that distinguish it from normal mature and young coconuts. Kopyor water has a milky, creamy, nutty, bitter, and astringent taste with an oily aftertaste and mouthfeel. Kopyor flesh is soft and moist and gives a sandy mouth feel. This study analyzed the sensory attributes of the kopyor endosperm for the first time and compared it with those of normal mature and young coconuts. A gas chromatography mass spectrometry analysis showed that kopyor contained wider variety of metabolites than normal coconuts of the same age. Based on the differential analysis and orthogonal projections to latent structures-regression, kopyor water was characterized by the accumulation of flavor-related metabolites, such as amino acids and organic acids, which contributed to its sensory complexity. This study solidified the effects of maturation and endosperm type on metabolite accumulation in kopyor endosperm. This pioneering information will lead to the future use of kopyor and other unique coconuts worldwide for food, contributing to the sustainability of the coconut industry.

Effects of n-butanol production on metabolism and the photosystem in Synecococcus elongatus PCC 7942 based on metabolic flux and target proteome analyses.

Although n-butanol (BuOH) is an ideal fuel because of its superior physical properties, it has toxicity to microbes. Previously, a Synechococcus elongatus PCC 7942 derivative strain that produces BuOH from CO2 was developed by introducing six heterologous genes (BUOH-SE strain). To identify the bottleneck in BuOH production, the effects of BuOH production and its toxicity on central metabolism and the photosystem were investigated. Parental (WT) and BUOH-SE strains were cultured under autotrophic conditions. Consistent with the results of a previous study, BuOH production was observed only in the BUOH-SE strain. Isotopically non-stationary 13C-metabolic flux analysis revealed that the CO2 fixation rate was much larger than the BuOH production rate in the BUOH-SE strain (1.70 vs 0.03 mmol gDCW-1 h-1), implying that the carbon flow for BuOH biosynthesis was less affected by the entire flux distribution. No large difference was observed in the flux of metabolism between the WT and BUOH-SE strains. Contrastingly, in the photosystem, the chlorophyll content and maximum O2 evolution rate per dry cell weight of the BUOH-SE strain were decreased to 81% and 43% of the WT strain, respectively. Target proteome analysis revealed that the amounts of some proteins related to antennae (ApcA, ApcD, ApcE, and CpcC), photosystem II (PsbB, PsbU, and Psb28-2), and cytochrome b6f complex (PetB and PetC) in photosystems decreased in the BUOH-SE strain. The activation of photosynthesis would be a novel approach for further enhancing BuOH production in S. elongatus PCC 7942.

Identification of potential quality markers in Indonesia's Arabica specialty coffee using GC/MS-based metabolomics approach.

INTRODUCTION: The cupping test is a widely used method for quality assessment of Arabica coffee. However, the cupping test is limited by the low number of certified panelists and the low throughput. Therefore, an analytical-based quality assessment may be a promising tool to complement the cupping test. A present, there is no report investigating quality marker candidates, focusing only on "specialty" grade Arabica coffee from Indonesia. OBJECTIVE: This study identified the potential quality marker(s) in Arabica Specialty coffee at different stages (green beans, roasted beans, and brewed coffee. METHODS: The metabolite profiles of ten different Arabica specialty-grade coffees were analyzed with different cup scores using gas chromatography-mass spectrometry (GC/MS). From the ten samples, green coffee beans, roasted coffee beans, and brewed coffee were selected. In addition, an orthogonal projection to latent structure (OPLS) regression analysis was conducted to obtain a potential quality marker based on the variable importance in projection (VIP). The potential quality marker(s) were validated by GC/MS metabolome profiling and OPLS analysis of different sets of samples consisting of 35 Arabica specialty-grade coffee samples. RESULTS: In Arabica coffee samples, the OPLS model of the three stages showed galactinol to have a high VIP score. Galactinol showed a consistent positive correlation with cup scores at all stages of coffee production (green beans, roasted beans, and brewed coffee). The correlation suggests galactinol is a potential quality marker after further validation using different samples. CONCLUSION: GC/MS combined with OPLS regression analysis suggested galactinol as a quality marker and provide an early screening method for Arabica coffee quality that complements the cupping test performed by certified panelists.

Chitosan-based coating enriched with melezitose alters primary metabolites in fresh-cut pineapple during storage.

Demand for minimally processed fresh fruit is increasing due to its convenience. However, the distribution of fresh-cut fruits is limited because of their short shelf life. Pineapple, a popular tropical fruit, sold in fresh-cut form has a shelf life of approximately 5-7 days at 4 °C. Chitosan, an edible coating, is commonly used to prolong the shelf life of food products. Similarly, the sugar melezitose has been reported to change during pineapple ripening and may play a role in regulating the shelf life of pineapple. However, the direct effects of this sugar have yet to be studied. The objective of this study was to investigate the effect of chitosan coating with melezitose to prolong the shelf life of fresh-cut pineapple. Full-ripe Bogor pineapples from Okinawa, Japan, were cut into cubes and soaked in either chitosan 1.25%, melezitose 5 mg/L, or chitosan+melezitose and stored for 5 days under dark conditions (23.6 ± 0.5 °C; relative humidity, 40.0 ± 10.4%). None of the treatments significantly altered the weight loss or color changes in the fresh-cut fruit. However, treatment significantly altered the primary metabolites, namely quinic acid, sucrose, and xylitol based on orthogonal projection to latent structures data with the screening from p-value score. Moreover, cell-wall metabolism is possibly affected in pineapple cut fruit treated by chitosan-melezitose as shown from metabolite sets enrichment analysis. This study showed that chitosan added with melezitose might have potential to prolong the shelf-life of fresh-cut pineapple, providing a basis for further post-harvest studies of the whole pineapple fruit.

Improvement of the functional value of green soybean (edamame) using germination and tempe fermentation: A comparative metabolomics study.

Green soybean, also known as edamame, is a legume with high nutritional and functional value. Despite its growing popularity and potential health benefits, the functionality of green soybean has not been thoroughly studied. Previous research on the functionality of green soybean has largely focused on a limited number of specific, well-studied, bioactive metabolites, without comprehensively investigating the metabolome of this legume. Additionally, very few studies have explored the improvement of the functional value of green soybean. This study aimed to investigate the metabolome profile of green soybean, identify bioactive metabolites, and to further explore the potential improvement of the identified bioactive metabolites using germination and tempe fermentation. A total of 80 metabolites were annotated from green soybean using GC-MS and HPLC-PDA-MS. Among them, 16 important bioactive metabolites were identified: soy isoflavones daidzin, glycitin, genistin, malonyl daidzin, malonyl genistin, malonyl glycitin, acetyl daidzin, acetyl genistin, acetyl glycitin, daidzein, glycitein, and genistein, as well as other metabolites including 3,4-dihydroxybenzoic acid, 3-hydroxyanthranillic acid, 3-hydroxy-3-methylglutaric acid (meglutol), and 4-aminobutyric acid (GABA). Germination and tempe fermentation techniques were employed to potentially improve the concentrations of these bioactive metabolites. While showing improvements in amino acid contents, germination process did not improve bioactive metabolites significantly. In contrast, tempe fermentation was found to significantly increase the concentrations of daidzein, genistein, glycitein, acetyl genistin, acetyl daidzin, 3-hydroxyanthranillic acid, and meglutol (>2-fold increase with p < 0.05) while also improving amino acid levels. This study highlights the potentials of germination and fermentation to improve the functionality of legumes, particularly green soybean.

Antioxidant Activity and Metabolite Profiling of Xylocarpus granatum Extracts Using Gas Chromatography-Mass Spectrometry.

The potential application of Xylocarpus granatum, a mangrove species, as traditional medicine has been widely linked to its high secondary metabolite and antioxidant contents. However, few studies have been reported to identify and classify active metabolites responsible for such excellent biological activities. Therefore, the aim of this work was to determine the antioxidant activity, identify the metabolite profiles, and predict the metabolites acting as antioxidants in X. granatum extract using a gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach. The seeds, stems, fruit peel, pulp, leaves, and twigs of X. granatum were macerated with ethanol. Each extract was analyzed with GC-MS, and the data were processed using mass spectrometry data-independent analysis (MS-DIAL) software to identify the metabolites. The IC50 value of plant parts of X. granatum ranged from 7.73 to 295 ppm. A total of 153 metabolites were identified and confirmed in the X. granatum extracts. Among the identified metabolites, epicatechin and epigallocatechin were the two most abundant in the stem extracts and are expected to have the greatest potential as antioxidants. Principal component analysis (PCA) succeeded in grouping all parts of the plant into three groups based on the composition of the metabolites: group 1 (stems, fruit peel, and twigs), group 2 (seeds and pulp), and group 3 (leaves).

Metabolite Changes in Indonesian Tempe Production from Raw Soybeans to Over-Fermented Tempe.

Tempe is fermented soybean from Java, Indonesia, that can serve as a functional food due to its high nutritional content and positive impact on health. Although the tempe fermentation process is known to affect its nutrient content, changes in the metabolite profile during tempe production have not been comprehensively examined. Thus, this research applied a metabolomics approach to investigate the metabolite profile in each step of tempe production, from soybean soaking to over-fermentation. Fourteen samples of raw soybeans, i.e., soaked soybeans (24 h), steamed soybeans, fungal fermented soybeans, and over-fermented soybeans (up to 72 h), were collected. Untargeted metabolomics by gas chromatography/mass spectrometry (GC-MS) was used to determine soybean transformations from various fermentation times and identify disparity-related metabolites. The results showed that soybeans samples clustered together on the basis of the different fermentation steps. The results also showed that sugar, sugar alcohol, organic acids, and amino acids, as well as fermentation time, contributed to the soybean metabolite profile transformations. During the fermentation of tempe, sugars and sugar alcohols accumulated at the beginning of the process before gradually decreasing as fermentation progressed. Specifically, at the beginning of the fermentation, gentiobiose, galactinol, and glucarate were accumulated, and several metabolites such as glutamine, 4-hydroxyphenylacetic acid, and homocysteine increased along with the progression of fermentation. In addition, notable isoflavones daidzein and genistein increased from 24 h of fermentation until 72 h. This is the first report that provides a complete description of the metabolic profile of the tempe production from soybean soaking to over-fermentation. Through this study, the dynamic changes at each step of tempe production were revealed. This information can be beneficial to the tempe industry for the improvement of product quality based on metabolite profiling.

MALDI Mass Spectrometry Imaging Reveals the Existence of an N-Acyl-homoserine Lactone Quorum Sensing System in Pseudomonas putida Biofilms.

Quorum sensing (QS) is generally used to describe the process involving the release and recognition of signaling molecules, such as N-acyl-homoserine lactones, by bacteria to coordinate their response to population density and biofilm development. However, detailed information on the heterogeneity of QS metabolites in biofilms remains largely unknown. Here, we describe the utilization of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) to follow the production of specific metabolites, including QS metabolites, during Pseudomonas putida biofilm development. To do so, a method to grow an agar-based biofilm was first established, and MALDI-MSI was used to detect and visualize the distribution of QS metabolites in biofilms at different cultivation times. This study demonstrated that N-acyl-homoserine lactones are homogeneously produced in the early stages of P. putida biofilm formation. In contrast, the spatial distribution of quinolones and pyochelin correlated with the swarming motility of P. putida in mature biofilms. These two metabolites are involved in the production of extracellular polymeric substances and iron chelators. Our study thus contributes to establishing the specific temporal regulation and spatial distribution of N-acyl-homoserine lactone-related metabolites and quinolone and pyochelin in P. putida biofilms.

Metabolomics-driven strain improvement: A mini review.

In recent years, mass spectrometry-based metabolomics has been established as a powerful and versatile technique for studying cellular metabolism by comprehensive analysis of metabolites in the cell. Although there are many scientific reports on the use of metabolomics for the elucidation of mechanism and physiological changes occurring in the cell, there are surprisingly very few reports on its use for the identification of rate-limiting steps in a synthetic biological system that can lead to the actual improvement of the host organism. In this mini review, we discuss different strategies for improving strain performance using metabolomics data and compare the application of metabolomics-driven strain improvement techniques in different host microorganisms. Finally, we highlight several success stories on the use of metabolomics-driven strain improvement strategies, which led to significant bioproductivity improvements.

Investigation of the effect of processing on the component changes of single-origin chocolate during the bean-to-bar process.

Chocolate is one of the most popular sweets in the world. In recent years, the bean-to-bar process for chocolate production has attracted global attention. Bean-to-bar is a method of managing the whole production process from cocoa beans to chocolate bars, including single-origin chocolate (SOC). Many manufacturers aim to produce high-quality chocolate to maximize the flavor of cocoa beans. However, chocolate compounds are very complex due to many processes, and there are a limited number of studies on the SOC produced from the bean-to-bar process. Therefore, understanding the effects of processing is important for the growth of the chocolate industry. The objective of this study was to investigate the processing effect on the component changes of SOC during the bean-to-bar process. In this study, the component changes during the bean-to-bar process were monitored using gas chromatography/mass spectrometry (GC/MS). Then, the characteristics of SOC from five regions in Indonesia were further investigated. Lastly, the component profiles were combined with the data obtained from sensory evaluation. Our results showed that the influence of the manufacturing process was greater than that of the difference in the cocoa production area. Moreover, 1-pentanol, raffinose, and heptanoic acid were correlated with sweetness and dairy flavor, whereas glutamic acid, tartaric acid, 3-methyl-2-butanone, mannitol, and ethyl cinnamate were correlated with bitterness, astringency, and cocoa flavor, which were shown to be affected by fermentation, roasting, and sugar addition. This information might provide a basis for improving the chocolate production process and its quality related to the component profiles.

Metabolome analysis to investigate the effect of controlled fermentation on taste-related metabolites in terasi.

INTRODUCTION: Terasi is a fermented shrimp paste unique to Indonesia and is used in dishes to add umami and saltiness. In a previous study, the controlled fermentation of terasi was optimized using starters containing three bacterial isolates: Staphylococcus saprophyticus, Bacillus subtilis, and Lactobacillus murinus. However, the influence of controlled fermentation using these starters on the metabolites in terasi has not yet been studied. OBJECTIVES: Therefore, this study aimed to investigate the effect of controlled fermentation on taste-related metabolites in terasi using a metabolomics approach. RESULTS: Non-targeted analysis indicated that amino acids contributed to variations during fermentation. Subsequently, targeted analysis of amino acids revealed that terasi subjected to controlled fermentation using a starter with a 2:1:2 ratio of S. saprophyticus, B. subtilis, and L. murinus, respectively, resulted in a product containing D-amino acids, such as D-Asp, D-Gln, and D-Leu that was unique when compared to other terasi products prepared using controlled fermentation. Genetic analysis of isolates from the terasi produced using controlled fermentation was also carried out, and this is the first study to suggest that Staphylococcus spp. has the potential to produce D-amino acids. CONCLUSION: In conclusion, the ratio of bacterial species in starter cultures used in controlled fermentation influenced the amino acid profile of the product and starters with a higher ratio of Staphylococcus spp. may result in the production of D-amino acids.

Unique metabolite profiles of Indonesian cocoa beans from different origins and their correlation with temperature.

Chocolate flavors vary depending on the origin of the cocoa beans used. Differences in soil, microorganisms, and environmental factors contribute to the formation of flavor precursors in cocoa beans. During cocoa bean fermentation, environmental temperature has been shown to alter metabolite concentrations. However, the correlation between the metabolite profile of cocoa beans and the temperature of their region of origin has not been fully defined. In this study, the metabolite profiles of Indonesian cocoa beans of various origins were evaluated using gas chromatography/mass spectrometry-based analysis, and were found to differ depending on the origin of the bean. Subsequently, the correlation between metabolite profile and environmental temperature of the origin was assessed using orthogonal projection to latent structure regression (OPLS-R) analysis. The analysis revealed that seven metabolites were associated with temperature: γ-aminobutyric acid (GABA), ethanolamine, glycerol, isocitric acid + citric acid, succinic acid, malic acid, and saccharic acid. The findings of this study will be valuable to chocolate industries for the production of single-origin chocolates.

Metabolomics approach to elucidate the importance of count size in commercial penaeid shrimps: white leg shrimp (Litopenaeus vannamei) and black tiger shrimp (Penaeusmonodon).

Currently, count size is applied globally as a grading standard to sell head-less shell-on farmed shrimp. Although count size does not indicate directly the quality of shrimp, the price of shrimp generally increases proportionally with the increase of shrimp size. The importance of the size of white leg shrimp has been previously reported, where a strong correlation was found between size and metabolome data. In this study, we aimed to improve the predictive power of the orthogonal projection to latent structure (OPLS) model by expanding the metabolite coverage using liquid chromatography mass-spectrometry (LC/MS) and gas chromatography-mass spectrometry (GC/MS) analysis. The training set consisted of 11 different-sized white leg shrimps from Indonesia and was validated in a step-wise manner by introducing an independent dataset consisting of commercial shrimp from the Japanese market. The first validation set consisted of commercial white leg shrimp, resulting in standard deviation error estimation and prediction values of 1.648 and 2.617, respectively. IMP and AMP, which are metabolites responsible for the umami taste in crustaceans, showed the highest variable importance in projection (VIP) scores and positively correlated with the increase in shrimp size. The second validation was carried out to evaluate the applicability of the size-metabolome relationship to other commercial penaeid shrimp species. The commercial black tiger shrimps with count sizes of 31/40, 21/25, 16/20, and 13/15 failed to predict the size of shrimp, suggesting that the importance of size in relation to the metabolome profile was rather species-specific.

Dynamic Changes in the Bacterial Community and Metabolic Profile during Fermentation of Low-Salt Shrimp Paste (Terasi).

Low-salt shrimp paste, or terasi, is an Indonesian fermented food made from planktonic shrimp mixed with a low concentration of salt. Since high daily intake of sodium is deemed unhealthy, reduction of salt content in shrimp paste production is desired. Until now, there is no reported investigation on the bacterial population and metabolite composition of terasi during fermentation. In this study, the bacterial community of terasi was assessed using high-throughput sequencing of the 16S rRNA V3-V4 region. From this analysis, Tetragenococcus, Aloicoccus, Alkalibacillus, Atopostipes, and Alkalibacterium were found to be the dominant bacterial genus in low-salt shrimp paste. GC/MS-based metabolite profiling was also conducted to monitor the metabolite changes during shrimp paste fermentation. Results showed that acetylated amino acids increased, while glutamine levels decreased, during the fermentation of low-salt shrimp paste. At the start of shrimp paste fermentation, Tetragenococcus predominated with histamine and cadaverine accumulation. At the end of fermentation, there was an increase in 4-hydroxyphenyl acetic acid and indole-3-acetic acid levels, as well as the predominance of Atopostipes. Moreover, we found that aspartic acid increased during fermentation. Based on our findings, we recommend that fermentation of low-salt shrimp paste be done for 7 to 21 days, in order to produce shrimp paste that has high nutritional content and reduced health risk.

Application of gas chromatography-mass spectrometry-based metabolomics in food science and technology.

Metabolomics is a tool used for quantitative assessment of metabolites that has been applied extensively in the field of food science. Recently, metabolomics-based gas chromatography-mass spectrometry (GC/MS) is becoming a common tool for analyzing, not only volatile compounds, but also non-volatile compounds due to the development of various derivatization methods. Although several studies have reviewed the application of metabolomics in food science, this present review article specifically focuses on metabolomics research using GC/MS for analysis of non-volatile compounds such as sugars, amino acids, and organic acids. From exhaustive literature research, the application of GC/MS-based metabolomics for non-volatile compounds in food science includes discriminating food samples based on cultivars and authentication of food samples to prevent food fraud, characterizing the profile of food samples to provide a general overview of the sample, evaluating stress-response, optimizing postharvest processes based on metabolic changes, monitoring changes during growth and food processing, evaluating and predicting food quality, and evaluating food shelf-life. GC/MS-based analysis of non-volatile compounds has been proven to be extremely valuable in food science, and might open new avenues for future researchers and engineers to develop instruments or improving production process in food industry.

Effects of Soaking Tempe in Vinegar on Metabolome and Sensory Profiles.

Tempe is a fermented soybean food that is globally renowned for its high protein content. Methods of preparing tempe vary worldwide, and include soaking in vinegar before fermentation. This study aimed to determine the effects of soaking in vinegar by metabolome analysis, gas chromatography/mass spectrometry, and sensory attribute evaluation. Vinegar affected metabolism during tempe fermentation, which led to altered metabolite profiles in the final product. We validated the metabolite profiles of two types of tempe using triangle tests and rate-all-that-apply (RATA) tests, which revealed that the sensory attributes of a golden-brown color, ammonia smell, pleasant smell, salty flavor, and acceptance significantly differed (p < 0.05) between the two types of tempe. A high concentration of specific amino acids in the control tempe explained a strong ammonia smell, saltiness, and darker golden-brown sensory attributes. Tempe soaked in vinegar contained high concentrations of metabolites associated with a roasted aroma and cooked meat. In conclusion, most RATA panelists who were being introduced to tempe preferred that soaked in vinegar to the control that was not.

Comparative metabolomics and sensory evaluation of pineapple (Ananas comosus) reveal the importance of ripening stage compared to cultivar.

The pineapple ripening stage is determined at the time of harvest and can be classified into the C0 to C4 stage based on its peel color. C1 and C4 pineapples are the most commonly exported products with high demand. Pineapple also has many cultivars with different tastes and appearances. However, there are limited studies regarding the metabolite and taste profiles of pineapple from different cultivars and ripening stages using a metabolomics approach. Therefore, the objective of this study was to investigate the metabolite and sensory profiles of pineapple from different cultivars and different ripening stages. Three cultivars of pineapple (Red Spanish, Smooth Cayenne, and Queen) and C1, C3, and C4 stages from Indonesia, Japan, the Philippines, and Taiwan, respectively, were analyzed by gas chromatography/mass spectrometry (GC/MS). The data obtained from GC/MS analysis were combined with the data obtained from sensory evaluation, which showed that sourness and firmness contributed to C1 fruits with metabolites correlated to isocitric acid+citric acid, malic acid, ascorbic acid, and quinic acid, while sweetness, juiciness, and high acceptability contributed to C4 fruits with metabolites that correlated were asparagine, serine, glycine, threonic acid, sucrose, and 5-hydroxytryptamine. GC/MS analysis using different pineapple cultivars also showed characteristic metabolites for each cultivar. Prediction of the sensory profile was performed by investigating the relative intensity of taste-related metabolites. This information can provide a basis for improving pineapple taste quality related to metabolites, depending on the cultivar and ripening stage.

Characterization of five Indonesian mangoes using gas chromatography-mass spectrometry-based metabolic profiling and sensory evaluation.

Indonesia is one of the world's leading mango producers and grows many cultivars. However, only a few cultivars have been commercialized, perhaps because of limited information on consumer preferences that meet the market demands. Here, non-targeted gas chromatography-mass spectrometry (GC-MS)-based metabolome analysis was used to characterize five Indonesian mango cultivars considering their taste characteristics. A total of 95 components (47 annotated and 48 unknown metabolites) were identified. Cultivars with a higher general impression score (Arumanis 143 and Gedong) in principal component analysis (PCA) accumulated more sugars and sweetening components, such as glycine and lyxose. Meanwhile, cultivars with a lower general impression score in PCA (Lalijiwo and Cengkir Indramayu) accumulated more aspartic acid, isocitric acid, and citric acid, which increase sourness; methionine, which is a precursor of sulfur-containing volatile aroma components; and phenylalanine, which contributes to bitterness. Furthermore, orthogonal projection to latent structures discriminant analysis revealed that nicotinic acid, glutamic acid, aspartic acid, glycine, and ribose characterized higher or lower general impression cultivars. In addition, metabolic profiling of eight mango cultivars, including five Indonesian and three overseas cultivars, suggested that taste was more influential than differences in cultivars, production areas, and cultivation conditions by its hydrophilic primary metabolomics. These findings will serve as fundamental data for future mango industry development considering the association between the unique taste of each cultivar and its metabolites as well as the consumer preferences for Indonesian mango.

Gas chromatography-mass spectrometry-based metabolite profiling and sensory profile of Indonesian fermented food (tempe) from various legumes.

Tempe is an Indonesian fermented food prepared from soybean or other non-soy legumes. Non-soy legumes based tempes have been reported to have a nutritional profile different from that of soybean-based tempe. However, a comprehensive study of the metabolite and sensory profiles of legume tempes has not been conducted. This study investigated the metabolite profile of legumes before and after fermentation using a metabolomic approach and its relation to the sensory profile. Four different legumes, namely red kidney bean, soybean, cowpea bean, and jack bean, and four kinds of tempe prepared from the abovementioned legumes were subjected to gas chromatography-mass spectrometry (GC-MS) analysis. These tempe samples were fermented in two different production places, Japan and Indonesia. In total, 83 metabolites were annotated from all samples. Principal component analysis (PCA) showed that the samples were separated based on their type (legume and tempe) along PC1 with a 36.3% variance, in which sugars and amino acids significantly contributed to the separation. In addition, samples were separated along PC2 with a 17.2% variance based on the different production places. The combination of 75% soybean and 25% red kidney bean (75S:25R) could increase the concentrations of amino acids that were initially low in soybean tempe. The 75S:25R tempe showed no significant differences in taste and texture preference compared to the 100% soybean tempe, based on sensory result. These findings provide evidence that metabolomics could be used to identify the differences between tempes from different legumes.

Gas chromatography/mass spectrometry-based metabolite profiling of coffee beans obtained from different altitudes and origins with various postharvest processing.

INTRODUCTION: Coffee is a popular beverage because of its pleasant aroma and distinctive flavor. The flavor of coffee results from chemical transformations influenced by various intrinsic and extrinsic factors, including altitude, geographical origin, and postharvest processing. Despite is the importance of grading coffee quality, there is no report on the dominant factor that influences the metabolomic profile of green coffee beans and the correlated metabolites for each factor. OBJECTIVE: This study investigated the total metabolite profile of coffees from different altitudes and coffees subjected to different postharvest processing. METHOD: Arabica green coffee beans obtained from different geographical origins and different altitudes (400 and 800 m) and produced by different postharvest processes (dry, honey, and washed process) were used in this study. Coffee samples obtained from altitudes of 400-1600 m above sea level from various origins that were produced by the washed method were used for further study with regard to altitudes. Samples were subjected to gas chromatography/mass spectrometry (GC/MS) analysis and visualized using principal component analysis (PCA) and orthogonal partial least squares (OPLS) regression analysis. RESULTS: The PCA results showed sample separation based on postharvest processing in PC1 and sample separation based on altitude in PC2. A clear separation between samples from different altitudes was observed if the samples were subjected to the same postharvest processing method, and the samples were of the same origin. Based on this result, OPLS analysis was conducted using coffee samples obtained from various altitudes with the same postharvest processing. An OPLS model using altitude as a response variable and 79 metabolites annotated from the GC/MS analysis as an explanatory variable was constructed with good R2 and Q2 values. CONCLUSION: Postharvest processing was found to be the dominant factor affecting coffee metabolite composition; this was followed by geographical origin and altitude. The metabolites glutamic acid and galactinol were associated with the washed and honey process, while glycine, lysine, sorbose, fructose, glyceric acid, and glycolic acid were associated with the dry process. Two metabolites with high variable influence on projection scores in the OPLS model for altitude were inositol and serotonin, which showed positive and negative correlations, respectively. This is the first study to report characteristic coffee metabolites obtained from different altitudes.