Changes in microflora and biochemical composition during the Baceman stage of traditional indonesian Kecap (soy sauce) production

Indonesian soy sauce (kecap) is made from black soybeans in a traditional way which involves two microbiological stages: a solid-state fermentation and a brine fermentation. This study is concerned with the brine fermentation, called baceman. Samples from different kecap producers were analyzed for (bio)chemical content and micro-organisms. It was found that the final composition of the baceman differed from manufacturer to manufacturer, and even within companies large differences were found in microflora and the amounts of fermentation products, formol nitrogen and salt concentration. The main fermentation products were lactate, acetate, glycerol and ethanol. Pediococcus halophilus, staphylococci, a coryneform bacterium and yeasts belonging to Candida, Debaromyces and Sterigmatomyces were isolated from the brines. Compared to Japanese soy sauce production, fermentation by yeasts does not play an important role in Indonesian kecap production. This is due to the fact that kecap is made from whole soybeans only, which are poor in sugars. After fermentation by P. halophilus no substrates are left for growth and ethanol production by yeasts. The presence of film forming yeasts can even lead to spoilage of the product.     

Influence of prebrining treatments on microbial and biochemical changes during the baceman stage in Indonesian kecap (soy sauce) production

Prior to the baceman stage or brine fermentation in Indonesian kecap (soy sauce) production, the soybeans undergo a number of treatments, such as soaking, cooking and a fungal solid state fermentation (bungkil stage). The influence of these prebrining steps on the baceman stage was investigated. Acidification during soaking inhibited bacterial growth during the solid state fermentation, causing lower initial numbers of bacteria in and a slower acidification of the baceman. Cooking time influenced the softness of the beans and thus fungal growth during the bungkil stage. Increasing the cooking time from 1 to 3 h resulted in a better solubility of macromolecules and gave higher final concentrations of fermentation products and formol nitrogen in baceman. When cooking time was increased from 3 to 5 h only slight differences could be observed. Length of the bungkil stage had some minor influences; the amount of fermentation products and residual monosaccharides decreased by 16% when the length was increased from 2 to 7 d. The highest amounts of formol nitrogen were found with 5 d of bungkil fermentation. The addition of rice flour showed that the absence of yeast fermentation in baceman is related to the lack of sugars after the previous lactic acid fermentation. In addition to yeast fermentation, the growth of fungi during the bungkil stage was also positively influenced by the addition of rice flour. Sun drying and crumbling bungkil caused lower enzyme activities and resulted in lower amounts of formol nitrogen and glycerol. Growth of Pediococcus halophilus during the baceman stage was faster when bungkil was sun dried, although the final concentrations of fermentation products were lower due to a lower content of amino acids which resulted in less buffering. Increasing the amount of bungkil added to salty water caused a similar increase in formol nitrogen and fermentation products.     

Profiling of dynamic changes in the microbial community during the soy sauce fermentation process

Soy sauce is a traditional condiment manufactured by natural inoculation and mixed culture fermentation. As is well known, it is the microbial community that plays an important role in the formation of its flavors. However, to date, its dynamic changes during the long period of fermentation process are still unclear, intensively constraining the improvement and control of the soy sauce quality. In this work, we revealed the dynamic changes of the microbial community by combining a cultured dependent method and a cultured independent method of polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis. Results indicated that the two methods verified and complemented each other in profiling microbial community, and that significant dynamics of the microbial community existed during the fermentation process, especially the strong inhibition of the growth of most of the microbes when entering into the mash stage from the koji stage. In the analysis of bacterial community, Staphylococcus and Bacillus were found to be the dominant bacteria and detected in the whole fermentation process. Kurthia and Klebsiella began to appear in the koji stage and then fade away in the early stage of the mash fermentation. In the analysis of fungal community, Aspergillus sojae and Zygosaccharomyces rouxii were found to be the dominant fungi in the koji and mash fermentation, respectively. It was clearly shown that when A. sojae decreased and disappeared in the middle stage of the mash fermentation, Z. rouxii appeared and increased at the meantime. Aspergillus parasiticus, Trichosporon ovoides and Trichosporon asahii also appeared in the koji and the early period of the mash fermentation and disappeared thereafter. Similar to Z. rouxii, Millerozyma farinosa and Peronospora farinosa were also found spontaneously which appeared in the mid-late period of the mash fermentation. The principal component analysis suggested that the microbial community underwent significant changes in the early period of the fermentation and, thereafter, tended to the stabilization in the mid-late periods. This study gave us important clues to understand the fermentation process and can serve as a foundation for improving the quality of soy sauce in the future.     

Microbiological and biochemical changes during the fermentation of maize (Zea mays) grains formasa production

Microorganisms associated with fermentation ofmasa wereLactobacillus plantarum, Pediococcus acidilactici, Lactobacillus fermentum andSaccharomyces cerevisiae. During the fermentation of maize grains, the temperature and moisture increased and the pH decreased. Most amino acids decreased in concentration during fermentation, with glutamic acid being the most abundant amino acid, but he protein content of the masa increased during fermentation. The bacteria played the major role in the fermentation.

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Résumé Les microorganismes associés avec la fermentation demasa sontLactobacillus plantarum, pediococcus acidilactici, Lactobacillus fermentum etSaccharomyces cerevisiae. Durant la fermentation de grains de mais, la température et l'humidité augmentent, et le pH diminue. La concentration de la plupart des acides aminés diminue durant la fermentation. L'acide aminé le plus abondant est l'acide glutamique. Toutefois, le contenu en protéines dumasa augmente au cours de la fermentation. Les bactéries jouent le rôle majeur dans la fermentation.

     

Microbial population and biochemical changes during production of protein-enriched fufu

Summary Candida utilis strain BKT4 and Saccharomyces cerevisiae strain BKT7 isolated from burukutu (a local wine brewed from sorghum) were used to enrich fufu. During the fermentation process, there were changes in the microbiological and biochemical characteristics of the cassava. The total viable counts increased with increasing fermentation time while the counts of the lactics and fungi increased at the later stages of the fermentation due to the acidity of the medium. Various bacteria (Bacillus, Staphylococcus, Klebsiella, Escherichia, Streptococcus, Lactobacillus, Leuconostoc, Corynebacterium), moulds (Penicillium, Aspergillus, Fusarium, Mucor, Rhizopus) and yeasts (Candida, Saccharomyces, Hansenula, Rhodotorula) were found to be associated with the fermentation process. The pH of the fermenting cassava increased from 4.2 to 5.7 after 72 h while the cyanide level decreased from 2.2 mg/kg to 0.7 mg/kg over the same period of fermentation. Fufu (prepared by crushing and sieving fermenting cassava roots) enriched with 0.5 g of C. utilis strain BKT4, S. cerevisiae BKT7 and a mixed culture of the two organisms revealed a crude protein of 7.90, 6.34 and 10.0% respectively as compared to 2% protein content of the enriched fufu. There was a corresponding increase in protein content of the product as the quantity of the enrichment yeast was increased from 0.5 to 3.0 g. The aroma of the enriched fufu was preferred to that of the commercial fufu. Generally, good acceptability and organoleptic qualities (colour, taste, texture and aroma) of the protein enriched fufu was best achieved within 48 h of enrichment. The results of this study suggest that fufu can be made more nutritious with yeasts particularly Candida utilis strain BKT4 and Saccharomyces cerevisiae strain BKT7.     

Physical factors influencing the production of strawberry aroma byPseudomonas fragi grown in skim milk

Summary The influence of temperature, agitation speed, pH and biomass on the synthesis of 19 metabolites contributing to a strawberry aroma was followed over a 72 h fermentation of skim milk byPseudomonas fragi. Amongst the major odor-active metabolites were ethyl butyrate, ethyl hexanoate, ethyl 2-hexenoate, ethyl crotonate, ethyl isovalerate and ethyl 2-methyl hexanoate. Up to 17 ppm of some of these metabolites were detected at 60 h of fermentation, approximately 36 h after the beginning of the stationary growth phase. The production of most odor-active metabolites was higher at 11°C and 150 RPM than at 15, 20 or 25°C and 200 or 250 RPM. The development of off-aromas was observed at high temperatures and at high agitation speeds.     

Allantoin-N concentration changes and analysis of the influencing factors on its changes during different manure composting

Allantoin is one of important nitrogenous compounds in manure. In this study, the simulation experiment of aerobic composting was adopted to explore concentration changes, degradation and relevant influencing factors of allantoin-N during six manure composting. The result showed that the allantoin-N concentration was markedly different among different manures. The various livestock and poultry excreted 1.92-11.14gkg(-1) allantoin-N which accounted for 9.98-32.27% of the total excreted nitrogen. The changing trend of the allantoin-N concentration firstly increased (for 0-14 days), then decreased (for 14-70 days) during different manure composting, and the allantoin-N concentration after composting was lower than the initial allantoin-N concentration in all manure composting. During allantoin degradation for 14-70 days of composting, the half-life of allantoin-N was 57.76 days in broiler manure, 46.21 days in layer-hen manure, 27.73 days in hog manure, 25.67 days in sow manure, 38.51 days in young pig manure and 15.75 days in dairy manure, and the sequence in the half-life was chicken manure>pig manure>dairy manure. Allantoin degradation conformed to first-order kinetics. Through the correlation analysis, hippuric acid, hydrolyzable nitrogen, amino acid-nitrogen, HUN fraction, NO(3)(-)-N and total hydrolyzable nitrogen could be closely related to allantoin-N transforming during composting. Humification could be the main influencing factor for reducing allantoin-N concentration during composting.     

Some biochemical changes during leaf rolling in Ctenanthe setosa (Marantaceae)

The changes in the levels of proline, sugar and soluble protein during leaf rolling and its relationship to osmotic adjustment were studied in laboratory conditions. Upon irrigation of plants which have rolled leaves, many sugar crystals occurred on the abaxial surface of the leaves in Ctenanthe setosa (Rosc.) Eichler. The sugar crystals were determined to have sucrose, glucose and fructose. The levels of reducing sugars and proline are higher in rolled leaves while soluble protein levels in rolled leaves are lower than those of unrolled leaves. It was found 1–3, 9–13, 16–21 and 24–28 crystals at degree of leaf rolling 23, 28, 47 and 52%, respectively. Finally, we found a significant correlation between the crystal number and degree of leaf rolling in Ctenanthe setosa. In addition, soluble sugars are found predominant accumulating solute in the plant and are of major importance as a contributor to osmotic adjustment during leaf rolling.     

Isolation and identification of the umami enhancing compounds in Japanese soy sauce

To clarify the key compounds that account for the umami taste of soy sauce, a typical Japanese soy sauce, Koikuchi Shoyu, was separated by preparative chromatography, and the umami enhancing fractions were screened on the basis of an umami intensity of a 6.0 mM monosodium L-glutamate (MSG) solution. Liquid chromatography-time of flight mass spectrometry (LC-TOFMS), 1D/2D nuclear magnetic resonance spectroscopy (NMR) studies of the umami enhancing fractions led to the identification of N-(1-deoxy-D-fructos-1-yl)pyroglutamic acid (Fru-pGlu), N-(1-deoxy-D-fructos-1-yl)valine (Fru-Val), N-(1-deoxy-D-fructos-1-yl)methionine (Fru-Met), pyroglutamylglutamine (pGlu-Gln), and pyroglutamylglycine (pGlu-Gly). Although all the compounds identified were at sub-threshold concentrations in the soy sauce, a taste reconstitution experiment revealed that they contributed part of the umami taste of the soy sauce.     

超滤法浓缩谷氨酰胺转胺酶的影响因素研究

对微生物谷氨酰胺转胺酶(MTG)超滤浓缩的工艺条件进行了探讨及优化。实验采用截留分子量为30 kDa的聚醚砜(PES)膜,当发酵液初始pH为7,超滤浓缩倍数为4倍时,可以得到理想的MTG回收率。同时对超滤液中蛋白酶的变化进行了分析,发现随着超滤倍数的提高蛋白酶也逐渐提高,但在浓缩4倍以后达到较稳定的水平。聚醚砜(PES)超滤膜使用后用稀释的NaOH溶液浸泡清洗处理50 min后,膜通量可以恢复98.12%。     

Physical and functional interactions of the lysophosphatidic acid receptors with PDZ domain-containing Rho guanine nucleotide exchange factors (RhoGEFs)

Lysophosphatidic acid (LPA) is a serum-derived phospholipid that induces a variety of biological responses in various cells via heterotrimeric G protein-coupled receptors (GPCRs) including LPA1, LPA2, and LPA3. LPA-induced cytoskeletal changes are mediated by Rho family small GTPases, such as RhoA, Rac1, and Cdc42. One of these small GTPases, RhoA, may be activated via Galpha(12/13)-linked Rho-specific guanine nucleotide exchange factors (RhoGEFs) under LPA stimulation although the detailed mechanisms are poorly understood. Here, we show that the C terminus of LPA1 and LPA2 but not LPA3 interact with the PDZ domains of PDZ domain-containing RhoGEFs, PDZ-RhoGEF, and LARG, which are comprised of PDZ, RGS, Dbl homology (DH), and pleckstrin homology (PH) domains. In LPA1- and LPA2-transfected HEK293 cells, LPA-induced RhoA activation was observed although the C terminus of LPA1 and LPA2 mutants, which failed to interact with the PDZ domains, did not cause LPA-induced RhoA activation. Furthermore, overexpression of the PDZ domains of PDZ domain-containing RhoGEFs served as dominant negative mutants for LPA-induced RhoA activation. Taken together, these results indicate that formation of the LPA receptor/PDZ domain-containing RhoGEF complex plays a pivotal role in LPA-induced RhoA activation.     

Characterization of factors involved in the production of 2(E)-nonenal during mashing

To characterize the factors involved in the production of volatile aldehydes during mashing, a model mashing experiment was done. After we inactivated the endogenous lipoxygenase (LOX) activity in the mash by mashing at 70 degrees C for 30 min, further incubation with recombinant barley LOX-1 stimulated the accumulation of 2(E)-nonenal; however, this effect was significantly reduced by boiling the mash sample. The result suggests that both LOX-1 and a heat-stable enzymatic factor are involved in the production of 2(E)-nonenal during mashing. Malt contained fatty acid hydroperoxide lyase-like activity (HPL-like activity) that transformed 9-hydroperoxy-10(E), 12(Z)-octadecadienoic and 13-hydroperoxy-9(Z), 11(E)-octadecadienoic acid into 2(E)-nonenal and hexanal, respectively. Proteinase K sensitivity tests showed that they are distinct factors. 9-HPL-like activity survived through the mashing at 70 degrees C for 30 min but was inactivated by boiling, suggesting it will be the heat-stable enzymatic factor found in the model mashing experiment.     

Freezing tolerance of chickpea: biochemical and molecular changes at vegetative stage

The aim of this study was to find a correlation between the freezing tolerance of three chickpea (Cicer arietinum L.) cultivars (?nci, I??k-05, and Sar?-98) and their wild relative C. echinospermum and physiological responses. Chickpea plants (15-d-old) were subjected to cold acclimation (CA) (10 °C for 7 d), freezing (-3 or -5 °C for 2 h), and subsequent rewarming (25 °C for 7 d). In two separate experiments with three replications, we determined growth, water status, photosystem 2 photochemical activity, photosynthetic pigments, H₂O₂, malondialdehyde, and proline content, relative leakage ratio, antioxidant enzyme activities, and gene expressions in cultivars different in freezing tolerance. Freezing temperatures adversely affected all the physiological parameters of all cultivars. Rewarming did not lead to complete recovery. The cultivar ?nci was more tolerant to the freezing temperatures than others.     

Endocrine changes during the previtellogenic stage of the great sturgeon,Huso huso (Linnaeus, 1758)

The study aimed to investigate changes in serum concentrations of sex steroids, thyroid hormones, stress indices, cholesterol, triacylglycerol, calcium and phosphorus, as well as the growth in the 3‐year old previtellogenic stage of great sturgeon, Huso huso over a 6‐month period. Forty individually marked fish (mean weight 6913 g) were divided among three circular tanks under a natural temperature and photoperiod. Every 1.5 months fish were weighed and blood samples taken for serum analysis. Fish showed significant changes in 17β estradiol, testosterone, triiodothyronine (T₃), thyroxine (T₄), adrenocorticotropic hormone, cortisol, cholesterol, and phosphorus, but not in triacylglycerol and calcium concentrations. From the January onset of the experiment to the end of the trial in July, there was a decrease in sex steroids and cortisol concentrations as well as a decline in T₃ concentrations from March and in T₄ from February to July. The mean weight of fish increased significantly from the beginning to the end of the experiment. Although the oocyte diameter increased from 197 to 202 μm, the difference was not significant. The histological data on oocytes suggest that the great sturgeon, like the other sturgeons, has a heterogeneous asynchronous ovarian development in the early stage of reproduction. This data might be useful to the further understanding of the physiology of Huso huso and/or to improve its culture. Moreover, it leads to a general increase in the understanding of the basic reproductive biology of this valuable chondrostean species.     

Porous alumina beads for immobilization of lactic acid bacteria and its application for repeated-batch fermentation in soy sauce production

Porous alumina beads with controlled pores were prepared for the immobilization of lactic acid bacteria to improve soy sauce productivity, and the alumina support with the highest lactic acid productivity was used for repeated-batch fermentation. Immobilized lactic acid bacteria could be used 5 times in repeated-batch fermentation, where higher productivities were obtained than that in conventional fermentation. The lactic acid fermentation process was mathematically modeled from the material balance and the rate equation. The simulated results agreed with the experimental ones.