Bioavailability of Iron in Fermented Soybeans

Hemoglobin depletion-repletion assay was used for determining iron bioavailability. The relative biological value (RBV) of iron in boiled nonfermented soybeans was the lowest among the products evaluated. The RBV of iron increased from 60.1% in boiled nonfermented soybeans to 86.7% by lactic acid producing microorganisms and to 87.5% by Rhizopus oligosporus fermentation (FeSO₄= 100%). Results of this research suggested that fermentation by lactic acid producing organisms and Rhizopus oligosporus increased the RBV of iron.     

The phytate and phytase of soybean tempeh

Soybeans were fermented into tempeh by Rhizopus oligosporus NRRL 2710. The phytic acid content of soybeans was reduced by about one-third as a result of this fermentation, while an equivalent amount of phosphate was released in the tempeh. The reduction of phytic acid was due to phytase elaborated by the mould of the fermentation. The pH optimum of this enzyme was 5.6 and the K_m of the phytase-phytate reaction was 0.28 × 10^?3 M.     

Enhancements of isoflavone aglycones, total phenolic content, and antioxidant activity of black soybean by solid-state fermentation with Rhizopus spp.

In the present study, a solid-state fermentation process of black soybean was developed. Three filamentous fungi including Rhizopus oligosporus (BCRC 31996), R. oligosporus (NTU-5), and Rhizopus oryzae (BCRC 30894) were cultivated with steam-cooked intact and dehulled black soybeans. It was found that fermentation enhanced the total phenolic and isoflavone aglycone content as well as antioxidant activity of the black soybean methanol [80 % (v/v)] extracts. Among the three candidates, R. oligosporus BCRC 31996 was chosen as the working strain, and dehulled Tainan NO.3 black soybeans were used as the substrate based on the relatively high total phenolic content, isoflavone aglycone accumulation, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect of the fermented extracts. In a 6-day fermentation, extracts of the fermented dehulled black soybeans yielded higher total phenolic content (2,876.2 μg/g) which was 1.16 times of the result from the intact soybean extracts. The DPPH scavenging effect of the fermented dehulled black soybean extract reached its maximum on the third day. The activity of β-glucosidase of dehulled black soybean samples increased with time and resulted in accumulation of isoflavone aglycones. The product of solid-state black soybean fermentation serves as a functional ingredient in the products of nutritional supplements and health foods.     

Role of Carbohydrate-Cleaving Enzymes in Phenolic Antioxidant Mobilization from Whole Soybean Fermented with Rhizopus oligosporus

Previous research has suggested a relationship between free phenolic content and β-glucosidase activity in solid-state fermented food substrates and to amylase activity in germinating soybeans. This study was undertaken to examine the role of a number of carbohydrate-cleaving enzymes in phenolic antioxidant mobilization from whole soybean during solid-state fermentation. In addition to total soluble phenolic content, α- and β-glucosidase, α-amylase, and β-glucuronidase activities were measured in extracts of soybean fermented with a food-grade fungus, Rhizopus oligosporus. Antioxidant activity of the extracts was determined as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. Our results demonstrate that while total soluble phenolic content increased 120–135% in the extracts, increased antioxidant activity (+61%) was limited to the early fermentation period, with activity decreasing with increased culture time. Higher antioxidant activity was linked to increased glucosidase and glucuronidase activities, while high total phenolic content partly linked to increased amylase activity. The overall results (enzymatic activities and phenolic antioxidant contents) suggest the possible involvement of lignin remobilization and/or degradation activities, as well as phenolic detoxification activities, by Rhizopus oligosporus in phenolic antioxidant mobilization from fermented whole soybean.     

In vitro DNA damage protection and anti‐inflammatory effects of Tartary buckwheats (Fagopyrum tataricum L. Gaertn) fermented by filamentous fungi

The present work was designed to investigate the phenolic profiles, DNA damage protection and anti‐inflammatory effects of Tartary buckwheat fermented by Rhizopus oryzae 40469, Rhizopus oryzae 40503 and Rhizopus oligosporus 3152. Six phenolic compounds were characterised and quantified. Regardless of fermentation, rutin was the dominant phenolic substance in Tartary buckwheat. Fermentation significantly enhanced total phenolic and flavonoid contents, as well as DNA scission protection. Rhizopus oryzae 40469‐fermented sample had the highest content of phenolics, while R. oligosporus 3152‐fermented sample had the strongest inhibitory effect on DNA scission. Tartary buckwheat, regardless of fermentation, inhibited nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA levels in LPS‐induced RAW 264.7 cells. Moreover, the sample fermented with R. oryzae 40503 had the strongest inhibitory activity. Those results indicated that fermented Tartary buckwheat has potential applications as a novel nutraceutical or functional food for preventing DNA damage‐induced disease and inflammation.     

Changes in fatty acid,simple sugar,and oligosaccharide content of cowpea (Vigna unguiculata) flour as a result of soaking,boiling, and fermentation with Rhizopus microsporus var. oligosporus

Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus were investigated. The major fatty acids in flour made from both nonfermented and fermented cowpeas were linoleic, palmitic, and linolenic. With the exception of lower amounts of lauric, palmitic, linoleic, and linolenic acids and slightly higher amounts of lignoceric acid, the remaining fatty acids in flour made from soaked cowpeas were essentially unchanged from the control flour made from cowpeas that were not soaked, boiled or fermented. Soaking followed by boiling generally increased amounts of fatty acids in flour compared to the control. Rhizopus microsporus did not utilize lipid during 24 h of fermentation. Soaking decreased the amount of sucrose and stachyose by 39% and 18.4%, respectively, whereas soaking followed by boiling caused decreases of 58.3% and 49.3%. Complete elimination of sucrose, raffinose, and stachyose was achieved after 15 h of fermentation.     

Reduction in Phytic Acid Levels in Soybeans During Tempeh Production, Storage and Frying

Tempeh was prepared from Delmar variety soybeans inoculated with the traditional Indonesian inoculum (usar) and two pure culture strains of the mould Rhizopus oligosporus (BTU3K1 and CT11K2). The preparatory treatments during tempeh production decreased the phytic acid content (% dry weight) of soybeans, except for the fist soaking which significantly increased the phytic acid content. The phytic acid content of soaked soybeans was halved during tempeh fermentation and was further reduced when tempeh was stored for 72 hr at 5° and at 30°C. Deep fat frying of tempeh in peanut oil further halved the phytic acid content. Less than 10% of the phytic acid remained after tempeh fermentation, storage and frying.     

Isoflavone Conversion of Black Soybean by Immobilized Rhizopus spp.

Isoflavones exhibit many bioactive benefits, such as antioxidation, antimutagenic effects, and reduction of symptoms of postmenopause conditions. Aglycone forms of isoflavone have shown more biological effects over their glycosylated ones. Most isoflavones in nature, however, exist as glycosylated forms and cannot easily be absorbed in the intestines. The purpose of this study was to develop a fermentation process of black soybean to produce functional food using a Luffa cylindrical fiber biofilm reactor. Three filamentous-fungi, including Rhizopus oligosporus (BCRC 31996), Rhizopus oligosporus (NTU-5), and Rhizopus oryzae (BCRC 30894), were cultivated in black soybean medium. The assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect of fermented broth and isoflavone aglycosylation rate of genistin and daidzin were evaluated as indicators to determine the most suitable strain. After a 2-day cultivation in flasks, DPPH radical scavenging effect of R. oligosporus NTU-5 reached 83%, which is the maximum value among three strains. R. oligosporus NTU-5 was subsequently chosen as target strain and used for the scale-up of fungal-based aerobic growth. The optimal cultivation condition obtained in a 5-L bioreactor with Luffa cylindrical fiber was 30°C, 0.1 vvm aeration, 100 rpm agitation, 10% inoculum volume, and 6% (w/v) black soybean as medium. After a 6-day cultivation, R. oligosporus NTU-5 converted isoflavones to their aglycones, daidzein and genistein, and these were 59.7 and 23.6 μM, respectively. Isoflavone aglycosylation rate of daidzin and genistin were 77.6 and 31.8%, respectively. The DPPH scavenging effect was 62%.     

Degradation of anti-nutritional factors and reduction of immunoreactivity of tempeh by co-fermentation with Rhizopus oligosporus RT-3 and Actinomucor elegans DCY-1

The effects of solid-state fermentation with four filamentous fungi (Rhizopus oligosporus, Actinomucor elegans, Neurospora crassa and Rhizopus oryzae) and their combination on the degradation of protein allergens and anti-nutritional factors (ANFs) of tempeh were evaluated. Glycinin, β-conglycinin, trypsin inhibitor and flatulence-causing oligosaccharides were significantly hydrolysed by all assayed strains but the level of reduction of ANFs depended on the strain. ELISA was conducted to evaluate IgE immunoreactivity using sera from soy sensitive individuals. Results revealed that co-fermentation of R. oligosporus and A. elegans resulted in the highest reduction in IgE immunoreactivity for all sera used and showed greatest degradations on α’, α, β, acidic subunits (100% hydrolysed) and extensive hydrolysis of flatulence-causing oligosaccharides. Tempeh fermented with R. oligosporus and A. elegans displayed high level of soluble protein and peptide (<10 kD) content. Co-fermentation of R. oligosporus and A. elegans was proved to be effective in producing hypoallergenic tempeh.     

Single‐cell protein production through microbial conversion of lignocellulosic residue (wheat bran) for animal feed

Agricultural residue (wheat bran) rich in carbohydrates was utilized in the fermentation process to produce microbial biomass. Single‐cell biomass consists of the dried cells of microorganisms, which are used as protein supplements in human food and in animal feed. In the present study, two different microorganisms (Candida utilis and Rhizopus oligosporus) were studied for biomass production. To enhance the nutritional contents of wheat bran, a number of different fermentation parameters (effect of inoculum size, age of inoculum, incubation period, moisture to substrate ratio and incubation temperature) were optimized. Maximum yield was obtained at an inoculum size of 10% (v/w), with the age of the inoculum being a 48 h old culture. A fermentation period of 48 h was found to give the maximum protein yield and viable counts of yeast cells and mould hyphae. The microorganisms showed good growth at 30 °C. After complete optimization of the fermentation parameters, a batch of wheat bran was fermented with C. utilis and R. oligosporus under the optimized conditions, resulting in a maximum crude protein yield of 41.02% compared with the 4.21% crude protein of the non‐fermented wheat bran. Copyright © 2015 The Institute of Brewing & Distilling     

Fermentation of Corn Gluten Meal with Aspergillus oryzae and Rhizopus oligosporus

PER values determined for corn gluten meal (CGM) and CGM fermented with Aspergillus oryzae NRRL 1988 were not significantly different (P > 0.05) and both diets failed to meet maintenance requirements of rats. In order to characterize some of the changes that occur during fungal fermentation, CGM was also fermented for 4 days at 28°C with A. oryzae NRRL 1988 and NRRL 506 and Rhizopus oligosporus NRRL 2710 and NRRL 2549, respectively. Proteolytic activity, pH, and nitrogen content increased rapidly between 20 and 70 hr for all the fungi. Decreases in some amino acids were observed, possibly due to their catabolism by the molds. Lysine as a proportion of total essential amino acids released by pepsin and pancreatin in vitro was increased as a result of these fungal fermentations.     

Physical and Chemical Changes in Fermented Peanut and Soybean Pastes Containing Kojis Prepared Using Aspergillus oryzae and Rhizopus oligosporus

Studies were made to determine and compare physical and chemical changes occurring during 90 days of fermentation of miso-like products containing peanuts and soybeans as well as a combination of these oilseeds. Two koji molds (Aspergillus oryzae and Rhizopus oligosporus) and two levels of NaCl (6 and 12%) were evaluated. The L color values decreased more rapidly in misos containing A. oryzae koji compared to misos containing R. oligosporus koji and changes occurred earlier in low-salt formulae than in high-salt formulae. The type of mold koji had no apparent effect on changes in viscosity. The free fatty acid content of misos increased dramatically during the first 4 days of fermentation. Misos containing A. oryzae koji had higher soluble nitrogen and free amino acid content in the final product than did those containing R. oligosporus kojis. Peanut miso products had higher soluble nitrogen contents than did respective soybean products; however, the type of oilseed had little effect on accumulation of free amino acids.     

Microbial Changes in Fermented Peanut and Soybean Pastes Containing Kojis Prepared using Aspergillus oryzae and Rhizopus oligosporus

Microbiological profiles of peanut and soybean misos containing 6 and 12% NaCl and kojis prepared with Aspergillus oryzae and Rhizopus oligosporus were monitored over a 90-day period of fermentation. Although total plate counts in misos containing R. oligosporus koji fluctuated while counts in misos containing A. oryzae koji remained constant during the fermentation period, the final microbial populations in sixteen test formulae were similar to the initial counts. Mold populations in mists containing two types of kojis declined similarly during fermentation. There was little difference in populations of Saccharomyces rouxii in misos containing the two types of mold kojis during the first month of fermentation; however, higher numbers of S. rouxii were noted in mitis containing R. oligosporus koji compared to those containing A. oryzae koji during later stages of fermentation. The final pH values of misos were similar, even though misos containing A. oryzae koji had a larger magnitude of drop in pH than did misos containing R. oligosporus koji over the 90-day test period.     

Degradation of Phytic Acid in Oncom (Fermented Peanut Press Cake)

Peanut press cake was fermented with Neurospora sitophila, Rhizopus oligosporus, a Neurospora strain isolated from Indonesian oncom, and mixed cultures of these molds. The phytic acid content of the uninoculated cake was 1.36% on a dry basis, but decreased rapidly during fermentation. Oncom prepared with R. oligosporus contained the least amount of phytic acid (0.05% after 72 hr of fermentation), while oncom prepared with the Indonesian strain of Neurospora contained the greatest amount of it (0.70%). Penta-, tetra-, tri-, di- and mono-phosphates of inositol, as well as inorganic phosphate and inositol, were found in the fermenting cake.     

Fermentation of legumes with Rhizopus oligosporus: effect on physicochemical,functional and microstructural properties

The present study investigated the effect of fermentation by Rhizopus oligosporus on the nutritional, functional, colour and microstructural properties of some commonly consumed legumes, that is, chickpea (kabuli and desi), pigeon pea and soybean. Results revealed a substantial (P < 0.05) increment in the protein (5–14%) and ash (5–15%) contents as well as those of essential (13–21%) and non-essential (3–15%) amino acids with fermentation. Fatty acid composition showed the varied concentrations of polyunsaturated, monounsaturated and saturated fatty acids in fermented legumes. Further, fermentation significantly (P < 0.05) modified the functional and colour properties of legumes. The alteration in the structural conformation of legumes upon fermentation was observed with scanning electron microscopy which confirmed the enzymatic action on the proteins, fibres and lipid bodies. The results concluded that fermentation of these legumes could be a potential approach in developing the novel functional foods to address the concerns of food and nutrition securities.     

Myo-inositol phosphates profile of buckwheat and quinoa seeds: Effects of hydrothermal processing and solid-state fermentation with Rhizopus oligosporus

Phytate content, bioavailability and myo-inositol phosphates profile were analysed in pseudocereals (i.e., white and coloured quinoa, buckwheat) subjected to thermal processing and solid-state fermentation with Rhizopus oligosporus. Fair buckwheat groats were characterised by the highest level of phytate (18.3 µmol/g), with 54% share of InsP₆ fraction. Processing (cooking, roasting, tempe-type fermentation) resulted in the significant decrease in phytate content, its bioavailability and the share of higher phosphorylated forms of myo-inositol (InsP_6-5) in the profile of all the samples. Fermentation of cereals resulted in generation of high amounts of inositol triphosphates, particularly in the case of buckwheat (32% share in the whole profile). The path of dephosphorylation, identified after fermentation of quinoa seeds including intermediate products – Ins(1,2,4,5,6)P₅ and Ins(1,2,6)P₃ – confirmed that the dominant phytase activity could be attributed to the presence of microbial 3-phytases from R. oligosporous.     

Solid-substrate fermentation of soybeans with Rhizopus spp.: comparison of discontinuous rotation with stationary bed fermentation

Tempe is a soybean food obtained by stationary solid-substrate fermentation using moulds (mainly Rhizopus spp.) as starter organism. Traditionally, tempe is fermented in static layer trays or wrapped packages. Due to heat and mass transfer limitations, gradients of temperature and gas atmosphere will result. Agitated fermentation can help to level heat and mass gradients, yielding better homogeneity. This type of process will not result in traditional tempe, but in individually fermented soybeans that could be processed into food ingredients. This report deals with the comparative effect of stationary versus agitated solid-substrate fermentation of soybeans on some chemical indices of substrate modification. For agitated solid-substrate fermentation, a 450-l size rotary-drum bioreactor was designed and constructed. Of two Rhizopus spp. tested, R. microsporus tolerated agitation quite well, as judged by changes of pH, amino nitrogen, ammonia, and soluble dry matter. The other species, R. oligosporus was strongly affected by agitation. This resulted in less pH increase (difference approx. 1.5 units), lower amino nitrogen levels (30-50% of levels in static fermentation), and lower levels of water-soluble non-lipid dry matter (30-50% of levels in static fermentation) with R. oligosporus agitated fermentation of soybeans controlled at 30 and 37 degrees C, compared to static fermentation at temperatures ranging between 25-35 and 30-40 degrees C, respectively.     

Proteolysis characteristics of Actinomucor elegans and Rhizopus oligosporus extracellular proteases under acidic conditions

Enzymatic hydrolysis of soybean protein isolate by the extracellular proteases from Actinomucor elegans and Rhizopus oligosporus at pH 3.0, 3.5, 5.0, 5.5 and 6.0 was investigated. The activity of the A. elegans protease is lower than that of R. oligosporus, but both proteases exhibit considerable degradation of soybean protein at pH 5.5 and 6.0. The water‐soluble protein content and the degree of hydrolysis of the hydrolysates are increased significantly, and bitterness values are very low. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) reveals that these proteases have different cutting sites on peptide polymers. At pH 5.5, there is a lower content of total free amino acids (39.20 mg per 100 mL; 62.68% hydrophobic amino acids) in the R. oligosporus protease hydrolysate. In conclusion, treatment with R. oligosporus protease at pH 5.5 achieves efficient degradation of soybean protein, suggesting a promising industrial process for making bitterless protein hydrolysates.     

Changes in Selected Chemical and Antinutritional Components during Tempeh Preparation Using Fresh and Hardened Common Beans

A tempeh-type fermented product was prepared from fresh and hard-to-cook (HTC) common beans. Fermentation decreased fat and fiber content and increased soluble solids, total and soluble proteins, soluble carbohydrates and pH of both bean samples. About 12% of solids were reduced during 72 hr fermentations. Results suggested that Rhyzopus oligosporus was capable of hydrolyzing the trypsin inhibitor and phytic acid of the substrate. Lectin and tannin contents decreased as a result of treatments applied during substrate preparation. Fresh and HTC beans may be converted by this fermentation technique into products of higher quality.     

Solid-state fermentation of Lathyrus sativus seeds using Aspergillus oryzae and Rhizopus oligosporus sp T-3 to eliminate the neurotoxin β-ODAP without loss of nutritional value

The presence of a neurotoxic amino acid, 3-N-oxalyl-L-2,3-diaminopropanoic acid (β-ODAP), in the seeds of grass pea (Lathyrus sativus) is the cause of an irreversible spastic paraparesis, neurolathyrism, after over-consumption. This is a negative factor in an otherwise very tasty, nutritious, easily cultivated and hardy food crop in Asia and Africa. The reduction of β-ODAP to less than 10% of the original content has been reached by fermenting L sativas Jamalpur seeds with Aspergillus oryzae NRRL 1988 for 48 h, followed by fermentation with Rhizopus oligosporus sp T-3 for 48 h. Other nutritional qualities were also improved in the fermented seed meal: increased content of protein, higher amino acid scores for sulphur-containing and aromatic amino acids, better resistance to high temperature and to oxidation, and drastic reduction of the flatulence factors.