Effect of soybean processing on content and bioaccessibility of folate, vitamin B12 and isoflavones in tofu and tempe

Biological properties of vitamin B12

Vitamin B12, cobalamin, is indispensable for humans owing to its participation in two biochemical reactions: the conversion of l-methylmalonyl coenzyme A to succinyl coenzyme A, and the formation of methionine by methylation of homocysteine. Eukaryotes, encompassing plants, fungi, animals and humans, do not synthesise vitamin B12, in contrast to prokaryotes. Humans must consume it in their diet. The most important sources include meat, milk and dairy products, fish, shellfish and eggs. Due to this, vegetarians are at risk to develop a vitamin B12 deficiency and it is recommended that they consume fortified food. Vitamin B12 behaves differently to most vitamins of the B complex in several aspects, e.g. it is more stable, has a very specific mechanism of absorption and is stored in large amounts in the organism. This review summarises all its biological aspects (including its structure and natural sources as well as its stability in food, pharmacokinetics and physiological function) as well as causes, symptoms, diagnosis (with a summary of analytical methods for its measurement), prevention and treatment of its deficiency, and its pharmacological use and potential toxicity.

Biological, dietetic and pharmacological properties of vitamin B9

Humans must obtain vitamin B9 (folate) from plant-based diet. The sources as well as the effect of food processing are discussed in detail. Industrial production, fortification and biofortification, kinetics, and physiological role in humans are described. As folate deficiency leads to several pathological states, current opinions toward prevention through fortification are discussed. Claimed risks of increased folate intake are mentioned as well as analytical ways for measurement of folate.

Impact of Lactobacillus acidophilus and Its Combination with Isoflavone Products on Calcium Status, Calcium Transporters, and Bone Metabolism Biomarkers in a Post-Menopausal Osteoporotic Rat Model

Osteoporosis in menopausal women requires alternatives to current medications, considering their adverse effects. In this context, probiotics and isoflavone products are promising dietary interventions. The objective of our study was to examine the impacts of Lactobacillus acidophilus and its combination with daidzein and tempeh on calcium status, calcium transporters, and bone metabolism biomarkers in a post-menopausal osteoporotic rat model. A total of 48 female Wistar rats were exposed to a two-stage experiment involving calcium deficit induction and subsequent dietary interventions across six groups. Calcium levels, the gene expression of TRPV5 and TRPV6 calcium transporters, bone histopathology, serum bone metabolism markers, and blood biochemistry were evaluated. The results revealed that, while decreasing serum calcium levels, the groups that received the probiotic L. acidophilus and isoflavone combination exhibited increased bone metabolism biomarkers and decreased calcium transporter expressions, akin to the effects of bisphosphonate. Additionally, significant improvements in bone histopathology were observed in these groups. However, the group receiving probiotic L. acidophilus alone did not exhibit significant changes in bone resorption biomarkers, calcium transporter expression, or various blood parameters. Meanwhile, the combination of probiotic L. acidophilus with tempeh positively influenced hematological parameters and reduced cholesterol and triglyceride levels, but it led to elevated blood glucose levels. Correlation analyses highlighted associations between serum calcium levels, calcium transporter expression, and bone metabolism biomarkers. In conclusion, our findings suggest that the daily consumption of probiotic L. acidophilus in combination with isoflavone products may improve bone health in ovariectomized rats, warranting further research to elucidate potential interactions with other nutrients.

How food matrices modulate folate bioaccessibility: A comprehensive overview of recent advances and challenges

The incomplete absorption of dietary folate makes it crucial to understand how food matrices affect folate bioaccessibility. Bioavailability encompasses bioaccessibility, which depicts the proportion that is liberated from the food matrix during digestion and becomes available for absorption. Bioavailability studies are expensive and difficult to control, whereas bioaccessibility studies utilize in vitro digestion models to parameterize the complex digestion, allowing the evaluation of the effect of food matrices on bioaccessibility. This review covers the folate contents in various food matrices, the methods used to determine and the factors affecting folate bioaccessibility, and the advances and challenges in understanding how food matrices affect folate bioaccessibility. The methods for determining bioaccessibility have been improved in the last decade. Current research shows that food matrices modulate folate bioaccessibility by affecting the liberation and stability of folate during digestion but do not provide enough information about folate and food component interactions at the molecular level. In addition, information on folate interconversion and degradation during digestion is scant, hindering our understanding of the impact of food matrices on folate stability. Moreover, the role of conjugase inhibitors should not be neglected when evaluating the nutritional value of food folates. Due to the complexity of food digestion, holistic methods should be applied to investigate bioaccessibility. By synthesizing the current state of knowledge on this topic, this review highlights the lack of in-depth understanding of the mechanisms of how food matrices modulate folate bioaccessibility and provides insights into potential strategies for accurate evaluation of the nutritional value of dietary folate.

B-Group Vitamins as Potential Prebiotic Candidates: Their Effects on the Human Gut Microbiome

In recent years, thousands of studies have demonstrated the importance of the gut microbiome for human health and its relationship with certain diseases. The search for new gut microbiome modulators has thus become an objective to beneficially alter the gut microbiome composition and/or metabolic activity, which may modify intestinal physiology. Growing evidence has shown that B-group vitamins might be considered as potential candidates as gut microbiome modulators. However, the relationship between the B-group vitamins and the gut microbiome remains largely unexplored. Studies have suggested that non-absorbed B-group vitamins administered orally can reach the distal intestine or even the colon where these vitamins may have potential health benefits for the host. Clinical trials supporting this effect are still limited. In this review, we discuss evidence regarding the modulatory effects of B-group vitamins on the gut microbiome with a focus on their potential role as prebiotic candidates.

Effect of Fermented Matrix on the Color and Stability of Strawberry and Blueberry Anthocyanins during the Storage of Fruit Yogurts and Soy-Based and Bean-Based Fruit Yogurt Alternatives

The effect of the fermented matrix on the color and the stability of anthocyanins contained in strawberry (Fragaria ananassa D.) and highbush blueberry (Vaccinium corymbosum L.) preparations for fruit yogurts, as well as soy-based (Glycine max L. Merr.) and bean-based (Phaseolus vulgaris L.) yogurt alternatives, stored for 8 weeks, was evaluated. To produce the fermented bean matrix, germinated seeds of white and black beans were used. The obtained fermented matrices had similar pH levels, while the soy-based and black bean-based yogurt alternatives were characterized by their high content of isoflavone aglycones and phenolic acids. The degradation of anthocyanins in strawberry and blueberry fermented products during storage followed first-order reaction kinetics. Significant differences were found depending on the fermented plant-based matrix. The fermented soy-based matrix demonstrated the highest T1/2 values for total anthocyanins (26.3 and 88.8 weeks for strawberry and blueberry products, respectively), whereas the yogurts exhibited the lowest values (13.3 and 49.3 weeks for strawberry and blueberry products, respectively). In the comparison of anthocyanin degradation during the storage of bean-based products, the pigments in the matrix obtained from fermented black beans showed better stability. During storage, the loss of anthocyanins was higher in strawberry products than in blueberry products, particularly with respect to malvidin and petunidin derivatives and acylated anthocyanins, which exhibited high stability. The total color difference (ΔE*) of blueberry plant-based products after an 8 week storage period ranged from 1.1 to 1.5. This data suggests that the addition of a coloring ingredient for industrial production may not be required.

Hawaijar - An ethnic vegan fermented soybean food of Manipur, India: A comprehensive review

Hawaijar, ethnic vegan fermented soybean food of Manipur, India is culturally and gastronomically important indigenously produced food. It is alkaline, sticky, mucilaginous and slightly pungent and bears similar properties with many fermented soybean foods of Southeast Asia like natto of Japan, douchi of China, thua nao of Thailand, choongkook jang of Korea. The functional microorganism is Bacillus and has numerous health benefits like fibrinolytic enzyme, antioxidant, antidiabetic, and ACE inhibitory activities. It is also very rich in nutrients but unscrupulous production method and sale lead to food safety issues. Huge potential pathogen population upto the level of 10^7-10 cfu/g Bacillus cereus and Proteus mirabilis were detected. Recent studies revealed presence of enterotoxic and urease gene in microorganisms originated from hawaijar. Improved and regulated food chain will result in hygienic and safe hawaijar. It has scope for functional food and nutraceutical global market and hold potential to provide employment to enhance the overall socioeconomic status of the region. Scientific production of fermented soybean over the traditional methods is summarized in this paper along with food safety and health benefits. Microbiological aspects on fermented soybean along with nutritive values are critically explained inside the paper.

Bioaccessibility and bioactive potential of different phytochemical classes from nutraceuticals and functional foods

Nutraceuticals and functional foods are composed of especially complex matrices, with polyphenols, carotenoids, minerals, and vitamins, among others, being the main classes of phytochemicals involved in their bioactivities. Despite their wide use, further investigations are needed to certify the proper release of these phytochemicals into the gastrointestinal medium, where the bioaccessibility assay is one of the most frequently used method. The aim of this review was to gather and describe different methods that can be used to assess the bioaccessibility of nutraceuticals and functional foods, along with the most important factors that can impact this process. The link between simulated digestion testing of phytochemicals and their in vitro bioactivity is also discussed, with a special focus on the potential of developing nutraceuticals and functional foods from simple plant materials. The bioactive potential of certain classes of phytochemicals from nutraceuticals and functional foods is susceptible to different variations during the bioaccessibility assessment, with different factors contributing to this variability, namely the chemical composition and the nature of the matrix. Regardless of the high number of studies, the current methodology fails to assume correlations between bioaccessibility and bioactivity, and the findings of this review indicate a necessity for updated and standardized protocols.

Characterisation of the Aroma Profile and Dynamic Changes in the Flavour of Stinky Tofu during Storage

Stinky tofu is a traditional Chinese food with wide consumption in China. Nevertheless, the dynamic changes in the flavour of stinky tofu during storage have yet to be investigated. In this study, the flavour changes of stinky tofu over six different storage periods were comprehensively analysed through sensory, electronic nose and gas chromatography-mass spectrometry (GC-MS) analyses. The results of the sensory and electronic nose analyses confirmed the changes in the flavour of stinky tofu across different storage periods. In the GC-MS analysis, 60 volatile compounds were detected during storage, and the odour activity values indicated that 29 of these 60 compounds significantly contributed to the aroma profile. During storage, the alcohol concentration of the stinky tofu gradually decreased while the acid and ester concentrations increased. According to a partial least squares analysis, 2-phenylethyl acetate, 2-phenylethyl propanoate, p-cresol, and phenylethyl alcohol, which were detected after 10 days of storage, promoting the release of an overripe apple-like odour from the stinky tofu. Findings regarding the flavour changes and characteristics of stinky tofu during different storage periods can provide a potential reference for recognising the quality of these products.

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.

Formula Optimization and Physicochemical Characterization of Tempe Drink Powder

Tempe is chosen as the main ingredient of tempe drink powder (TDP) due to its protein digestibility, phytochemical compounds, as well as vitamins and minerals. Previous studies had been conducted to develop TDP formula. The commercial TDP formula showed that improvement of quality aspects needs to be done so the product has better physical and chemical characteristics. In order to optimize the TDP formula, the viscosity, water solubility index (WSI), water absorption index (WAI), sedimentation index (SI), proximate, antioxidant activity, isoflavone content, GABA content, and physicochemical properties were analyzed. The optimized formula was done using the mixture experiment optimization method with optimization d-optimal to obtain the best formula. The optimization result showed that the best formula proportion consisted of 70% (w/w) Tempe flour, 18.23% (w/w) maltodextrin and 1.77% (w/w) guar gum. The best formula was chosen due to having better chemical characteristics compared with the commercial TDP and commercial soy drink powder (SDP), with protein content of 42.61%, antioxidant activity of 58.36 mgAEAC/100g, daidzein and genistein isoflavones of each 48.18 and 140.06 mg/100g and GABA of 21.24 mg/g. Based on the physical characteristics, the optimum formula had a lower viscosity value (18.67 cP) and WAI (2.58g/g) as well as a higher SI value (10.18%) and WSI (9.70%) compared with the commercial TDP. The optimum TDP formula has fulfilled the quality requirements based on the Indonesian National Standard (SNI 7612:2011) regarding soy drink powder.

Fermented Black Tea and Its Relationship with Gut Microbiota and Obesity: A Mini Review

Fermentation is one of the world’s oldest techniques for food preservation, nutrient enhancement, and alcohol manufacturing. During fermentation, carbohydrates such as glucose and starch are converted into other molecules, such as alcohol and acid, anaerobically through enzymatic action while generating energy for the microorganism or cells involved. Black tea is among the most popular fermented beverages; it is made from the dried tea leaves of the evergreen shrub plant known as Camellia sinensis. The adequate consumption of black tea is beneficial to health as it contains high levels of flavanols, also known as catechins, which act as effective antioxidants and are responsible for protecting the body against the development of illnesses, such as inflammation, diabetes, hypertension, cancer, and obesity. The prevalence of obesity is a severe public health concern associated with the incidence of various serious diseases and is now increasing, including in Malaysia. Advances in ‘omic’ research have allowed researchers to identify the pivotal role of the gut microbiota in the development of obesity. This review explores fermented black tea and its correlation with the regulation of the gut microbiota and obesity.

5-Methyltetrahydrofolate Is a Crucial Factor in Determining the Bioaccessibility of Folate in Bread

This study investigated the bioaccessibility of folate in wheat bread baked with different ingredients and processing methods. Next, different matrices were spiked with 5-methyltetrahydrofolate, gallic acid (GA), or both to investigate the stability of 5-methyltetrahydrofolate during in vitro digestion. The folate bioaccessibility in bread varied from 44 to 96%. The inclusion of whole-grain or faba bean flour significantly improved both folate content and bioaccessibility. Baking with yeast increased the folate content by 145% in bread but decreased folate bioaccessibility compared to the bread without added yeast because of the instability of 5-methyltetrahydrofolate. Spiking experiments confirmed oxidation as a critical reason for 5-methyltetrahydrofolate loss during digestion. However, GA protected this vitamer from degradation. Additionally, 5-methyltetrahydrofolate was less stable in whole-grain wheat matrices than other matrices. This study demonstrated that the stability of 5-methyltetrahydrofolate is crucial for folate bioaccessibility in bread, and methods for stabilizing this vitamer should be further studied.

Fermented Soy Products and Their Potential Health Benefits: A Review

In the growing search for therapeutic strategies, there is an interest in foods containing natural antioxidants and other bioactive compounds capable of preventing or reversing pathogenic processes associated with metabolic disease. Fermentation has been used as a potent way of improving the properties of soybean and their components. Microbial metabolism is responsible for producing the β-glucosidase enzyme that converts glycosidic isoflavones into aglycones with higher biological activity in fermented soy products, in addition to several end-metabolites associated with human health development, including peptides, phenolic acids, fatty acids, vitamins, flavonoids, minerals, and organic acids. Thus, several products have emerged from soybean fermentation by fungi, bacteria, or a combination of both. This review covers the key biological characteristics of soy and fermented soy products, including natto, miso, tofu, douchi, sufu, cheonggukjang, doenjang, kanjang, meju, tempeh, thua-nao, kinema, hawaijar, and tungrymbai. The inclusion of these foods in the diet has been associated with the reduction of chronic diseases, with potential anticancer, anti-obesity, antidiabetic, anticholesterol, anti-inflammatory, and neuroprotective effects. These biological activities and the recently studied potential of fermented soybean molecules against SARS-CoV-2 are discussed. Finally, a patent landscape is presented to provide the state-of-the-art of the transfer of knowledge from the scientific sphere to the industrial application.

Profiling of naturally occurring folates in a diverse soybean germplasm by HPLC-MS/MS

Soybean is a rich source of folates. We optimised the extraction and detection of folates from soybean seeds by HPLC-MS/MS and analysed the folate content and composition of 1074 accessions. Total folate content ranged from 64.51 to 691.24 μg/100 g fresh weight, with 10-fold variation, and 60 elite accessions with over 400 μg/100 g of total folate were identified. The most abundant component was 5-CHO-H4folate, which accounted for an average of 60% of total folate content. Seed-coat colour, seed weight, ecoregion, and accession type significantly affected soybean folate content. Furthermore, 5-CH3-H4folate correlated positively with seed protein (r = 0.24***) and negatively with oil (r = -0.26***). The geographical distribution of folate according to accession origin revealed that accessions from Northeast China contain higher amounts of total folate and 5-CHO-H4folate. This study provides comprehensive and novel insights into the folate profile of soybean, which will benefit soybean breeding for folate enhancement.

Vitamin B12 sources in non-animal foods: a systematic review

Interest in plant-based diets and vegetarianism is increasing worldwide, however, a concern for total vegetarians is vitamin B12 (B12) deficiency. We conducted a systematic review to investigate non-animal food sources of B12. Databases were PubMed, LILACS, Cochrane, Embase and Google Scholar, up to September 9, 2020. Quality of the eligible studies were assessed. We identified 25 studies which assessed B12 content in seaweeds, mushrooms, plants and fermented foods. Initial studies were microbiological bioassay, ELISA and HPLC. In the last decade, more sensitive method for real B12 determination was used, the liquid chromatography-electrospray ionization tandem mass spectrometry chromatograms. Real B12 content varied from mean (SD) mcg/portion size of seaweed hijiki 3 × 10-3/7 g to nori 1.03 - 2.68/sheet; mushroom white button cap 2 × 10-3(7 × 10-4)/20 g dry weight (dw) to shiitake 0.79(0.67)-1.12 (0.78)/20 g dw; and fermented foods from soy yogurt 20/cup. It is possible that daily recommendations for B12 can be met by a varied diet containing non-animal B12 food sources. Future research should consider different methods of storage, preparation, fermented foods and standardization of the production of certain foods.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2022.2053057.

To culture or not to culture: careful assessment of metabarcoding data is necessary when evaluating the microbiota of a modified-atmosphere-packaged vegetarian meat alternative throughout its shelf-life period

Background

As the increased consumption of ready-to-eat meat alternatives is a fairly recent trend, little is known about the composition and dynamics of the microbiota present on such products. Such information is nonetheless valuable in view of spoilage and food safety prevention. Even though refrigeration and modified-atmosphere-packaging (MAP) can extend the shelf-life period, microbial spoilage can still occur in these products. In the present study, the microbiota of a vegetarian alternative to poultry-based charcuterie was investigated during storage, contrasting the use of a culture-dependent method to a culture-independent metagenetic method.

Results

The former revealed that lactic acid bacteria (LAB) were the most abundant microbial group, specifically at the end of the shelf-life period, whereby Latilactobacillus sakei was the most abundant species. Metabarcoding analysis, in contrast, revealed that DNA of Xanthomonas was most prominently present, which likely was an artifact due to the presence of xanthan gum as an ingredient, followed by Streptococcus and Weissella.

Conclusions

Taken together, these results indicated that Lb. sakei was likely the most prominent specific spoilage organisms (SSO) and, additionally, that the use of metagenetic analysis needs to be interpreted with care in this specific type of product. In order to improve the performance of metagenetics in food samples with a high DNA matrix but a low bacterial DNA load, selective depletion techniques for matrix DNA could be explored.

Probiotic Potential of a Folate-Producing Strain Latilactobacillus sakei LZ217 and Its Modulation Effects on Human Gut Microbiota

Folate is a B-vitamin required for DNA synthesis, methylation, and cellular division, whose deficiencies are associated with various disorders and diseases. Currently, most folic acid used for fortification is synthesized chemically, causing undesirable side effects. However, using folate-producing probiotics is a viable option, which fortify folate in situ and regulate intestinal microbiota. In this study, the folate production potential of newly isolated strains from raw milk was analyzed by microbiological assay. Latilactobacillus sakei LZ217 showed the highest folate production in Folic Acid Assay Broth, 239.70 ± 0.03 ng/μL. The folate produced by LZ217 was identified as 5-methyltetrahydrofolate. LZ217 was tolerant to environmental stresses (temperature, pH, NaCl, and ethanol), and was resistant to gastrointestinal juices. Additionally, the in vitro effects of LZ217 on human gut microbiota were investigated by fecal slurry cultures. 16S rDNA gene sequencing indicated that fermented samples containing LZ217 significantly increased the abundance of phylum Firmicutes and genus Lactobacillus, Faecalibacterium, Ruminococcus 2, Butyricicoccus compared to not containing. Short-chain fatty acids (SCFAs) analysis revealed that LZ217 also increased the production of butyric acid by fermentation. Together, L. sakei LZ217 could be considered as a probiotic candidate to fortify folate and regulate intestinal microecology.

Folate metabolic profiling and expression of folate metabolism-related genes during panicle development in foxtail millet (Setaria italica (L.) P. Beauv)

BACKGROUND

Foxtail millet grain has higher folate content than other cereal crops. However, the folate metabolite content and the expression patterns of folate metabolite-related genes are unknown.

RESULTS

Liquid chromatography-mass spectrometry was used to investigate 12 folate metabolites in a foxtail millet panicle. The content of total folate and derivatives gradually decreased during panicle development. Polyglutamate 5-formyl-tetrahydrofolate was the major form. Twenty-eight genes involved in the folate metabolic pathway were identified through bioinformatic analysis. These genes in Setaria italica, S. viridis and Zea mays showed genomic collinearity. Phylogenetic analysis revealed that the folate-related genes were closely related among the C4 plants compared to C3 plants. The gene expressions were then studied at three panicle development stages. The gene expression patterns were classified into two groups, namely SiADCL1 and SiGGH as two key enzymes, which are responsible for folate synthesis and degradation; their expression levels were highest at the early panicle development stage, up to 179.11- and 163.88-fold, respectively. Their expression levels had a similar downward trend during panicle development and were significantly positively correlated with the concentration of total folate and folate derivatives. However, SiSHMT3 expression levels were significantly negatively correlated with total folate concentration.

CONCLUSION

Besides being the major determinants of folate and folate derivatives accumulation, SiADCL1 and SiGGH expression levels are key limiting factors in the foxtail millet panicle. Therefore, SiADCL1 and SiGGH expression levels can be targeted in genetic modification studies to improve folate content in foxtail millet seeds in the future. © 2021 Society of Chemical Industry.

Midlife intake of the isoflavone genistein and soy, and the risk of late-life cognitive impairment: the JPHC Saku Mental Health Study

BACKGROUND

The number of people with cognitive impairment, including dementia, in the world is steadily increasing. Although the consumption of isoflavones and soy is associated with a reduced risk of cardiovascular disease, it might also be associated with cognitive impairment. The low number of studies investigating the association between soy/isoflavone intake and cognitive function warrant additional research.

METHODS

The Japan Public Health Center-based prospective (JPHC) Study is a large population-based cohort. Midlife dietary intake of soy and the isoflavone genistein was assessed on two occasions: in the years 1995 and 2000. In 2014-2015, 1299 participants from Nagano prefecture completed a mental health screening. Of these, a total of 1036 participants were included in analyses. Logistic regression was used to determine Odds Ratios (OR) and 95% Confidence Intervals (CI) for the association between midlife energy-adjusted genistein and soy food intake and cognitive impairment.

RESULTS

There were 392 cases of cognitive impairment (346 cases of MCI and 46 cases of dementia). Compared to the lowest dietary quartile of energy-adjusted genistein intake, the highest quartile was significantly associated with cognitive impairment (OR=1.51; 95% CI, 1.02-2.24; p for trend=0.03) in the final multivariable analysis.

CONCLUSIONS

High midlife intake of the isoflavone genistein is associated with late-life cognitive impairment.

Nutritional Content and Characteristics of Pumpkin Cream Soup with Tempeh Addition as Supplementary Food for Elderly

An increase in the number of elderly people indicates a higher life expectancy. However, this is also a new challenge since the elderly tends to have age-related diseases, thus the physical, psychological, and sensory disorders that will affect their nutritional status. The development of geriatric foods such as cream soup made from pumpkin and tempeh is considered to be the solution to prevent this situation. This study used a factorial randomized design, containing processing methods (fresh and instant) and the addition of tempeh (0%, 75%, and 100%). Sensory evaluation (rating and ranking test), physical characteristics (pH, yield, rehydration, and viscosity), nutritional analysis (proximate, crude fibre, dietary fibre, vitamins B6 and B12, and β-carotene content), and acceptance analysis of cream soup fresh and instant were examined. Physical characterization revealed that the product had a pH of 5.4-5.7, a viscosity of 1250-2190 cP, a rehydration ratio of 5.51-6.47 g mL^-1, and a yield of 19.44%-26.9%. The result of sensory evaluation showed that the processing method and tempeh addition had a significant effect (p < 0.05) on the product acceptance. This also affects the nutritional value, in which fresh products had higher nutritional value than the instant product, and products with tempeh had higher ash, protein, dietary fibre, and vitamin B12 than products without tempeh. Based on this analysis, the instant cream soup with 75% tempeh is the best formula. In one portion size (50 g), instant cream soup with 75% tempeh met 10% or more of the Indonesian recommended dietary allowance (RDA) for the elderly in terms of protein, carbohydrates, fat, energy, dietary fibre, vitamin B12, vitamin B6, and vitamin A, so it can be recommended as a complementary food for the elderly.

The sensory, physical and nutritional quality profiles of purple sweet potato and soy-based snack bars for pregnant women

BACKGROUND

The deficiency of energy, protein, and other beneficial nutrients during pregnancy causes chronic energy deficiency (CED). This condition increases the chance of having babies with low birth weight (LBW) and various other health problems. To meet these nutritional needs, supplementary feeding is necessary in the form of snack bar, using local food ingredients, such as purple sweet potatoes and soybeans (PSPS). This study determines the differences in a few aspects of PSPS snack bar, such as sensory acceptability, physical quality, and nutritional content in several formulations.

DESIGN AND METHODS

The best three formulations were selected through sensory acceptability by involving 40 panelists and showed the following results P0 (commercial product), P2 (80% purple sweet potato: 20% soybean), and P3 (70% purple sweet potato: 30% soybean). Furthermore, these formulations were triplicated for further physical color test, the hardness and breaking force, as well as the nutritional analysis that includes both macro and micronutrients.

RESULTS

The results showed significant differences (p<0.05) in the sensory acceptability, physical quality, nutritional content (except carbohydrate and iron), and antioxidant activity.

CONCLUSIONS

In conclusion, snack bars with 70% purple sweet potato and 30% soybean gave the best formulation.

Tempeh: A semicentennial review on its health benefits, fermentation, safety, processing, sustainability, and affordability

Tempeh is a fermented food made of mainly soybeans and is a nutritious, affordable, and sustainable functional source of protein. Globally, tempeh is a widely accepted fermented product. Although there is a growing body of literature on tempeh, most research has focused on unfermented soybeans, thus the impact of tempeh fermentation on biological properties of soybeans has been largely left scattered. The objective of this review is to summarize the literature of tempeh fermentation over the past 60 years. A search of articles on tempeh published from 1960 to 2020 was performed using the Cochrane Library, Web of Science, EBSCOhost FSTA database, and Google Scholar. References from identified articles were reviewed for additional sources. In total, 321 papers were selected for this review, of which 64 papers were related to the health benefits of tempeh. This review concluded that sufficient evidence exists in the literature supporting tempeh fermentation as a low-cost, health-promoting, and sustainable food processing technology to produce protein-rich foods using various beans, legumes, and grains. This comprehensive review suggests further studies are needed on tempeh fermentation and its impact on human health; research and standardization of nonsoy tempeh; assessment of food safety-improving modification in tempeh production system; and initiatives supporting the sourcing of local ingredients in tempeh production.

Bioaccessibility of folate in faba bean, oat, rye and wheat matrices

Cereals and legumes are rich in folate. However, due to the instability of folate, processing and digestion can induce significant folate loss. In this paper, folate bioaccessibility of faba bean, oat, rye and wheat flours and pastes was studied using a static in vitro digestion model. Folate bioaccessibility depended on food matrices, varying from 42% to 67% in flours and from 40% to 123% in pastes. Digestion was associated with the interconversion of formyl folates, as well as the increase of oxidised vitamers and decrease of reduced vitamers. Especially in faba bean, 5-methyltetrahydrofolate showed surprisingly good stability both in digestion and heat treatment, resulting in high bioaccessibility. The physiological concentration of ascorbic acid did not stabilise folate in digestion; however, a higher level helped to maintain reduced vitamers. Heat treatment (10-min paste making) could improve folate bioaccessibility by liberating folate from the food matrices and by altering folate vitamer distribution.

Identification of a novel umami peptide in tempeh (Indonesian fermented soybean) and its binding mechanism to the umami receptor T1R

Tempeh, a traditional Indonesian soybean product produced by fermentation, is especially popular because of its umami taste. In this study, a novel umami peptide GENEEEDSGAIVTVK (GK-15) was identified in the small peptide (<3 kDa) fraction of the water extract of tempeh using LC-MS/MS analysis and database-assisted identification. The umami taste of GK-15 was further validated using sensory evaluation, which suggested that GK-15 may be one of the key components contributing to the umami taste in tempeh. To rationalize the biological effect of GK-15, molecular docking of GK-15 into the N-terminal extracellular ligand-binding domain of the umami (T1R) receptor was performed. ZDOCK data showed that GK-15 could perfectly bind either to the open or closed conformation of T1R3. To the best of our knowledge, the present work is the first study to focus on the screening of umami peptides from tempeh.

Identification of the prepared foods promising for dietary folate intake in Beijing, China

The aim of the present study was to analyze folate content and composition in foods consumed daily by Chinese people. The concentration of seven folate derivatives in sixty-four selected foods was determined by a liquid-chromatography tandem-mass spectrometry method. The total folate levels ranged from 0.28 to 129 µg/100 g fresh weight, with an average of 21.18 μg/100 g. The highest folate content was found in boiled egg yolk and waxy corn (>120 µg/100 g), abundant folate levels in cooked vegetables such as hot pepper, spinach, soybean sprout, stem lettuce, coriander, and broccoli (44-72 µg/100 g), and lowest in Coca Cola (0.28 µg/100 g). 5-Methyl-tetrahydrofolate was the major folate derivative in various foods, accounting for 72% of the total folates on average, with the highest being 90% in egg yolk. These data will enable estimation of the daily folate intake and allow dietary recommendations to improve folate status in humans.

Folate content and retention in wheat grains and wheat-based foods: Effects of storage, processing, and cooking methods

Folates are essential micronutrients for human health. The aim of this study was to evaluate the effects of storage, processing and cooking methods on folate content and identify factors with great influence on folate retention in wheat grains and wheat-based foods. For this, the folate levels of wheat grains after 2-8 months of storage, wheat flours, noodles, fermented dough, steamed bun, and bread were sequentially analyzed. An average of 26% folate loss was observed after eight-month storage in wheat grains. The milling process, with an extraction rate of 70%, led to a severe (71%) folate loss. The folate retention rate in noodles was 78%. Fermentation by yeast production enabled a 1.5-4-fold enhancement of folate levels in steamed bun and bread. Boiling, steaming and baking led to a folate loss of 13%, 16%, and 11%, respectively. These results help to guide industrial/household preparation of wheat-based foods for folate nutrition.

What is the cobalamin status among vegetarians and vegans in Australia?

Water-soluble vitamin B12 (cobalamin) plays a vital role in normal blood function and neurological functioning. Clinical and subclinical B12 deficiency has been notably reported in vegans, vegetarians, the elderly and metformin-treated diabetics. Currently, the prevalence of cobalamin deficiency among vegans and vegetarians in Australia is lacking; data on dietary intake including supplements and nutritional status are also limited. The increasing multiculturalism of Australia has seen an influx of imported foods, of which some may contain considerable vitamin B12. However, values for such foods are not included in the food composition databases. This review highlights the need to update the food composition database with culturally diverse foods containing vitamin B12. Moreover, the need for assessing dietary intakes and status using the most current best evidence and best practice on nutritional indicators (biochemical and functional biomarkers) to estimate the risk of deficiency and/or depletion is discussed.

Phenolic Compound Profile and Functionality of Aqueous Overripe Tempe Extracts

Tempe is a soy fermentation product and has been associated with many health benefits. It is usually consumed after 48 hours of fermentation; however extended fermentation is sometimes favoured. Since cooking involves water, it is of interest to study the health benefits of tempe water extract. In this study, we focused our study on total phenols, total flavonoids, DPPH free radical scavenging activity, cytotoxic activity, and identification of the main flavonoids. Our findings demonstrated that concentration of water-soluble flavonoids in tempe increased as fermentation time was prolonged. Fermentation for 60 hr resulted in extracts with very noticeable cytotoxic activity against MCF-7 cancer cell line (IC50 of 8.70 µg/ml). The cytotoxic activity of the extracts was fermentation time-dependent following non-linear relationship. The activity showed strong inverse correlation with total phenols and flavonoids in the extracts. LC-MS/MS data suggested that extracts from control and 24-hr fermented tempe demonstrated the highest responses for genistein, genistin, daidzein, daidzin, and glycitein, compared to those of other treatments and therefore suggested that excessive amount of the isoflavones, particularly genistein, induced cancer cell proliferation but lesser yet optimum concentration (observed at 60 hr-fermentation) contributed to otherwise effect.

Transcriptomic analysis of de novo folate biosynthetic genes in Lactobacillus plantarum strain 4_3 in fermented soybean

Folate is an important intermediate in cellular metabolism. However, because of a lack of key enzymes in the folate biosynthetic pathway, humans require supplementation with dietary folate. Some Lactobacillus plantarum strains have the ability to produce folate. To gain a better understanding of the folate biosynthetic pathway in the L. plantarum strain 4_3, which generates high folate yields, L. plantarum strain 4_3 was grown in folic acid casei medium (FACM) and fermented soybean, after obtaining a draft genome sequence. The pH values and folate yields were monitored during culturing, as were the transcriptomic profiles of cultured bacteria. The folate content increased for 12 h and then decreased before increasing again. All the genes involved in the de novo biosynthesis of folate were detected in both the genomic and transcriptomic data. The upregulation of the para-aminobenzoate biosynthesis pathway could explain the folate production in fermented soybean. Soybeans are a good substrate for the production of functional foods because of their well-suited cultivation and nutritional quality. The results of this study provide a good explanation for the high folate production observed during the fermentation of soybeans.

Proteomic study of bioactive peptides from tempe

Tempe is a traditional Indonesian fermented soybean mostly produced in small industries and sold locally throughout the country. Studies on the bioactive peptides in tempe are rare. Here, we studied bioactive peptides in samples from three tempe producers with different degrees of sanitation. The peptide sub-fractions of tempe from each producer were collected following water extraction, ultrafiltration (<3 kDa), gel filtration chromatography, and reversed phase-high performance liquid chromatography (RP-HPLC) separation followed by liquid chromatography-mass spectrometry (LC-MS). The MS spectra were then predicted using FindPept tools, and their biofunctionalities were confirmed with BIOPEP databases. There were few similar peptides found in tempe from the three producers. Peptides Val-His and Ala-Leu-Glu-Pro were found in tempe from all producers. Producers having a good sanitation level had more bioactive peptides than those with moderate or poor sanitation levels (58%, 43% and 35%, from good to poor sanitation). This work showed that the tempe from the three producers had antihypertensive, antidiabetic, antioxidative and antitumor peptides.

Influence of passion fruit by-product and fructooligosaccharides on the viability of Streptococcus thermophilus TH-4 and Lactobacillus rhamnosus LGG in folate bio-enriched fermented soy products and their effect on probiotic survival and folate bio-accessibility under in vitro simulated gastrointestinal conditions

This study aimed to evaluate the influence of passion fruit by-product (PFBP) and fructooligosaccharides (FOS) on the viability of Streptococcus thermophilus TH-4 and Lactobacillus rhamnosus LGG in folate bio-enriched fermented soy products and their effect on probiotic survival and folate bio-accessibility under in vitro simulated gastrointestinal conditions during storage of the products at 4 °C for up to 28 days (at days 1, 14, and 28). Kinetic parameters and folate contents before and after fermentation were also evaluated. Four different bio-enriched soy products in which the two microorganisms were used in co-cultures were studied and PFBP and/or FOS were added at 1 g/100 g, except for the control product. No differences (p < 0.05) between the fermented soy products (FSP) were observed for the maximum acidification rate (Vmax) and the time to reach the Vmax (Tmax) or pH 5.5 (Tf), indicating that the use of PFBP and/or FOS did not affect the fermentation kinetic parameters. Only Lb. rhamnosus LGG retained the desired viability (>8 log CFU/mL) during storage, whereas St. thermophilus TH-4 populations decreased by day 14 reaching counts between 6.4 and 5.5 log CFU/mL by day 28. The folate content of all FSP increased after fermentation and the simultaneous presence of PFBP and FOS stimulated the co-culture to increase folate production. Folate content in all FSP decreased during storage. Lb. rhamnosus LGG was recovered at the end of the simulated digestion, but PFBP and/or FOS did not affect recovery. The folate content increased during the gastrointestinal assay for all FSP, especially for FSP without supplementation, suggesting an in vitro increase of folate bio-accessibility. Therefore, the bio-enriched probiotic FSP presented a great potential as an innovative functional food by delivering probiotic microorganisms and providing 14% of the recommended daily folate intake. The folate content of the FSP might be increased during gastrointestinal stress conditions, which could contribute to increase the folate bio-accessibility in the gut.

Bioactivity of soy-based fermented foods: A review

For centuries, fermented soy foods have been dietary staples in Asia and, now, in response to consumer demand, they are available throughout the world. Fermentation bestows unique flavors, boosts nutritional values and increases or adds new functional properties. In this review, we describe the functional properties and underlying action mechanisms of soy-based fermented foods such as Natto, fermented soy milk, Tempeh and soy sauce. When possible, the contribution of specific bioactive components is highlighted. While numerous studies with in vitro and animal models have hinted at the functionality of fermented soy foods, ascribing health benefits requires well-designed, often complex human studies with analysis of diet, lifestyle, family and medical history combined with long-term follow-ups for each subject. In addition, the contribution of the microbiome to the bioactivities of fermented soy foods, possibly mediated through direct action or bioactive metabolites, needs to be studied. Potential synergy or other interactions among the microorganisms carrying out the fermentation and the host's microbial community may also contribute to food functionality, but the details still require elucidation. Finally, safety evaluation of fermented soy foods has been limited, but is essential in order to provide guidelines for consumption and confirm lack of toxicity.

Enhancing vitamin B12 content in co-fermented soy-milk via a Lotka Volterra model

Soybean products are popular because of its taste, digestibility, and health benefits. However, soybean lacks vitamin, mainly the low water-soluble vitamin B12. This study investigated the effects of fermentation conditions on the synthesis of vitamin B12, production of metabolites, and growth of Lactobacillus reuteri and Propionibacterium shermainii in fermented soy-milk. A Lotka Volterra model was successfully employed to describe the competition relationship between the two microorganisms under various fermentation conditions. A quadratic function between the ratio of interaction coefficients and vitamin B12 content was found. Higher vitamin B12 in soy-milk can be produced when the ratio of interaction coefficients approach to one. Compared with other fermented soybean products, fermented soy-milk contains more acetate, ethanol, and propionic acid. This study successfully demonstrated a mathematical model to enhance soy-milk vitamin B12 production.

High yield production of folates from soybean callus cultures in response to elicitors

Soybean (Indian variety, JS 335) callus growth and its folate content was sustained on Murashige and Skoog (MS) medium supplemented with optimized levels of auxins and cytokinins. Callus cultures exhibited moderate production of total folate. Callus growth was stimulated with highest biomass content of 21.3 g/L DW (24 days culture) on medium supplemented with 1.5 mg/L 2,4-dichlorophenoxy acetic acid (2,4-D) and 0.1 mg/L Kinetin (Kn). Total folate production was enhanced by an increase in indole-3-acetic acid (IAA) from 0.5 to 1.0 mg/L and decreased thereafter up to 1.5 mg/L. 2,4-D at 1.5 mg/L repressed the callus growth and also folate production. A concentration of 1.0 mg/L IAA and 0.2 mg/L Kn elicited folate production to a maximum total folate content of 323.82 µg/100 g DW. The results indicate that optimized medium for callus suspension cultures conceivably are applied for scale-up studies in bioreactors.

Lactic acid fermentation as a tool for increasing the folate content of foods

Folate is an essential micronutrient involved in numerous vital biological reactions. The dietary consumption of naturally occurring vitamin B9 is often inadequate in many countries, and supplementation or fortification programs (using synthetic folic acid) are implemented to alleviate folate deficiency. Other food-based alternatives are possible, such as the use of lactic acid bacteria (LAB) to synthesize folate during fermentation. Many studies have been conducted on this topic, and promising results were reported for some fermented dairy products. However, in other studies, folate consumption by LAB or rather low folate production were observed, resulting in fermented foods that may not significantly contribute to the recommended B9 intake. In addition, the optimum conditions for folate biosynthesis by LAB are still not clear. The aim of this review was thus to (i) clarify the ability of LAB to produce folate in food products, (ii) check if the production of folate by LAB in various fermented foods is sufficient to meet human vitamin B9 requirements and (iii) suggest ways to optimize folate production by LAB in fermented food products.

In situ production of active vitamin B12 in cereal matrices using Propionibacterium freudenreichii

The in situ production of active vitamin B12 was investigated in aqueous cereal‐based matrices with three strains of food‐grade Propionibacterium freudenreichii. Matrices prepared from malted barley flour (33% w/v; BM), barley flour (6%; BF), and wheat aleurone (15%; AM) were fermented. The effect of cobalt and the lower ligand 5,6‐dimethylbenzimidazole (DMBI) or its natural precursors (riboflavin and nicotinamide) on active B12 production was evaluated. Active B12 production was confirmed by UHPLC–UV–MS analysis. A B12 content of 12–37 μg·kg⁻¹ was produced in BM; this content increased 10‐fold with cobalt and reached 940–1,480 μg·kg⁻¹ with both cobalt and DMBI. With riboflavin and nicotinamide, B12 production in cobalt‐supplemented BM increased to 712 μg·kg⁻¹. Approximately, 10 μg·kg⁻¹ was achieved in BF and AM and was increased to 80 μg·kg⁻¹ in BF and 260 μg·kg⁻¹ in AM with cobalt and DMBI. The UHPLC and microbiological assay (MBA) results agreed when both cobalt and DMBI or riboflavin and nicotinamide were supplemented. However, MBA gave ca. 20%–40% higher results in BM and AM supplemented with cobalt, indicating the presence of human inactive analogues, such as pseudovitamin B12. This study demonstrates that cereal products can be naturally fortified with active B12 to a nutritionally relevant level by fermenting with P. freudenreichii.

Enhanced vitamin B12 production in an innovative lupin tempeh is due to synergic effects of Rhizopus and Propionibacterium in cofermentation

Fermentation represents a valuable and cost-effective approach for food stabilisation and nutritional improvement. Tempeh is an example of soybean solid-state fermentation. In this work, we investigated the possibility of producing a tempeh analogue containing high amounts of vitamin B12 using seeds of three different species of the legume lupin, namely Lupinus albus, L. angustifolius and L. mutabilis, with Rhizopus oligosporus and Propionibacterium freudenreichii cofermentation. Synergic effects of Rhizopus and Propionibacterium in increasing vitamin B12 up to 1230 ng/g dw was observed. These findings indicate that this cofermentation can improve lupin nutritional quality and safety to provide a tempeh analogue with added value for vegan and vegetarian communities and low-income populations. The level of potentially toxic lupin alkaloids was also monitored during the tempeh preparation.

Novel vitamin B12-producing Enterococcus spp. and preliminary in vitro evaluation of probiotic potentials

Vitamin B₁₂ is an essential nutrient required for crucial metabolic processes in humans. Vitamin B₁₂-producing lactic acid bacteria (LAB) have been attracting increased attentions currently because of the generally recognized as safe (GRAS) status. Most of recent studies focused on Lactobacillus, and little is known about B₁₂-producing Enterococcus. In the present study, five Enterococcus strains isolated from infant feces were identified as vitamin B₁₂ producers. Among them, Enterococcus faecium LZ86 had the highest B₁₂ production (499.8 ± 83.7 μg/L), and the B₁₂ compound from LZ86 was identified as the biological active adenosylcobalamin, using reversed phase high-performance liquid (RP-HPLC) chromatogram. We examined basic probiotic and safety properties of E. faecium LZ86 and found that it was able to survive harsh environmental conditions (hot temperature, cold temperature, ethanol and osmotic stresses), tolerate gastric acid (pH 2.0, 3 h) and bile salts (0.3%), and adhere to Caco-2 cells. We also showed that E. faecium LZ86 is devoid of transferable antibiotic resistance and potential virulence factors. Together, here we report a B₁₂-producing E. faecium strain LZ86 firstly, which has desirable probiotic properties and may serve as a good candidate for vitamin B₁₂ fortification in food industry.

Use of Bacillus amyloliquefaciens HZ-12 for High-Level Production of the Blood Glucose Lowering Compound, 1-Deoxynojirimycin (DNJ), and Nutraceutical Enriched Soybeans via Fermentation

1-Deoxynojirimycin (DNJ) is an efficient α-glucosidase inhibitor (α-GI) with potential applications in the prevention and treatment of diabetes. In this study, 16 Bacillus strains were screened for α-GI rate, and the strain HZ-12 with the highest α-GI rate was identified as Bacillus amyloliquefaciens through the analysis of physiological biochemical characteristics and 16S rDNA sequence. By LC-MS/Q-TOF analysis, the α-GI component produced by B. amyloliquefaciens HZ-12 was identified as DNJ. Soybean was used as the substrate for the solid-state fermentation; 870 mg/kg DNJ was produced by B. amyloliquefaciens HZ-12 after optimizing the fermentation conditions and media, which was 3.83-fold higher than the initial yield. Also, evaluations of nutraceutical enrichment in the form of anticoagulant activity, antioxidant activity, total nitrogen (TN), and total reducing sugars (TRS) of the B. amyloliquefaciens HZ-12 fermented soybeans were substantially higher than unfermented soybeans. This study provided a promising strain for high-level production of DNJ and produced nutraceutical enriched soybeans by fermentation.

Enhanced total phenolic and isoflavone aglycone content, antioxidant activity and DNA damage protection of soybeans processed by solid state fermentation with Rhizopus oligosporus RT-3

In this study,Rhizopus oligosporusRT-3, which was first isolated in our group, was used for solid state fermentation of soybeans (R. oligosporus-fermented soybeans, RFS) in a short time (22 h).

BluB/CobT2 fusion enzyme activity reveals mechanisms responsible for production of active form of vitamin B₁₂ by Propionibacterium freudenreichii

Background

Propionibacterium freudenreichii is a food grade bacterium that has gained attention as a producer of appreciable amounts of cobalamin, a cobamide with activity of vitamin B₁₂. Production of active form of vitamin is a prerequisite for attempts to naturally fortify foods with B₁₂ by microbial fermentation. Active vitamin B₁₂ is distinguished from the pseudovitamin by the presence of 5,6-dimethylbenzimidazole (DMBI) as the lower ligand. Genomic data indicate that P. freudenreichii possesses a fusion gene, bluB/cobT2, coding for a predicted phosphoribosyltransferase/nitroreductase, which is presumably involved in production of vitamin B₁₂. Understanding the mechanisms affecting the synthesis of different vitamin forms is useful for rational strain selection and essential for engineering of strains with improved B₁₂ production properties.

Results

Here, we investigated the activity of heterologously expressed and purified fusion enzyme BluB/CobT2. Our results show that BluB/CoBT2 is responsible for the biosynthesis of the DMBI base and its activation into α-ribazole phosphate, preparing it for attachment as the lower ligand of cobalamin. The fusion enzyme was found to be efficient in metabolite channeling and the enzymes’ inability to react with adenine, a lower ligand present in the pseudovitamin, revealed a mechanism favoring the production of the active form of the vitamin. P. freudenreichii did not produce cobalamin under strictly anaerobic conditions, confirming the requirement of oxygen for DMBI synthesis. In vivo experiments also revealed a clear preference for incorporating DMBI over adenine into cobamide under both microaerobic and anaerobic conditions.

Conclusions

The herein described BluB/CobT2 is responsible for the production and activation of DMBI. Fusing those two activities results in high pressure towards production of the true vitamin B₁₂ by efficiently activating DMBI formed within the same enzymatic complex. This indicates that BluB/CobT2 is the crucial enzyme in the B₁₂ biosynthetic pathway of P. freudenreichii. The GRAS organism status and the preference for synthesizing active vitamin form make P. freudenreichii a unique candidate for the in situ production of vitamin B₁₂ within food products.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-015-0363-9) contains supplementary material, which is available to authorized users.

Enhancing the vitamin B12 production and growth of Propionibacterium freudenreichii in tofu wastewater via a light-induced vitamin B12 riboswitch

The vitamin B12-dependent riboswitch is a crucial factor that regulates gene transcription to mediate the growth of and vitamin B12 synthesis by Propionibacterium freudenreichii. In this study, the effect of various wavelengths of light on the growth rate and vitamin B12 synthesis was studied. Red, green, and blue light-emitting diodes (LEDs) were selected, and a dark condition was used as the control. The microorganism growth rate was measured using a spectrophotometer and plate counting, while the vitamin B12 content was determined using an HPLC-based method. The optical density at 600 nm (OD600) values indicated that P. freudenreichii grew better under the continuous and discontinuous blue light conditions. Moreover, under the blue light condition, P. freudenreichii tended to have a higher growth rate (0.332 h(-1)) and vitamin B12 synthesis (ca. 10 μg/mL) in tofu wastewater than in dark conditions. HPLC analysis also showed that more methylcobalamin was produced under the blue light conditions than in the other conditions. The cbiB gene transcription results showed that blue light induced the synthesis of this vitamin B12 synthesis enzyme. Moreover, the results of inhibiting the expression of green fluorescent protein indicated that blue light removed the inhibition by the vitamin B12-dependent riboswitch. This method can be used to reduce fermentation time and produce more vitamin B12 in tofu wastewater.