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Solid-state fermentation with food-grade fungal strains can be applied to enhance the bioactive parameters of agro-industrial by-products. Tempe-type fermentation can be adapted to various substrates, but the key factor is the appropriate strain selection. The aim of this study was to compare the potential of Rhizopus strains for obtaining products of improved antioxidant activity from pumpkin oil cake. For this purpose, substances reacting with the Folin-Ciocalteu reagent, with free radical scavenging potential, as well as reducing power were assessed. The effect of the fermentation on the phytate level and inositol phosphate profile in the material was also monitored. The fermentation resulted in the significant enhancement of the antioxidant potential of pumpkin oil cake in the case of all the strains tested, but the most efficient one was R. oligosporus ATCC 64063. During the course of fermentation, the level of phytate in the material decreased (the highest reduction rate was observed in the oil cake fermented with R. oryzae CBS 372.63), while peptides and fungal glucosamine were accumulated. Tempe-type fermentation can be considered as an alternative way of improving the bioactive parameters of pumpkin oil cake and, thanks to the various activities of different Rhizopus strains, it is possible to obtain products of desired parameters.

Tempe-type fermentation originating from Indonesia can enhance the antioxidant activity of plant material. However, this biological potential depends on substrates and applied microorganisms. This study aimed to determine whether co-fermentation with Rhizopus oligosporus and Lactobacillus plantarum improved antioxidant activity of tempe obtained from grass pea seeds with flaxseed oil-cake addition (up to 30%). For this purpose, substances reacting with Folin-Ciocalteu reagent and free radicals scavenging potential were measured in water-soluble fractions and dialysates from simulated in vitro digestion. Additionally, the water-soluble phenolic profile was estimated. The higher level of water-extractable compounds with antioxidant activity was determined in co-fermentation products than in fungal fermentation products. Moreover, the fermentation process with the use of L. plantarum contributed to a greater accumulation of some phenolic acids (gallic acid, protocatechuic acid) in tempe without having a negative effect on the levels of other phenolic compounds determined in fungal fermented tempe. During in vitro digestion simulating the human digestive tract, more antioxidant compounds were released from products obtained after co-fermentation than fungal fermentation. An addition of 20% flaxseed oil-cake and the application of bacterial-fungal co-fermentation, can be considered as an alternative tool to enhance the antioxidant parameters of grass pea tempe.

Background: Tempeh is a food product obtained from legumes by means of solid-state fermentation with Rhizopus sp. Our previous research proved that mixed-culture inoculum may also be successfully applied. The objective of present research was to study the proteolytic activity of R. microsporus var. chinensis and A. oryzae during tempeh-type fermentation of grass pea seeds, and the effect of inoculum composition on the protein level and in vitro protein bioavailability in products., Methods: Fermentation substrate were soaked and cooked grass pea seeds. Material was mixed with single- or mixed-culture inoculum, and incubated in perforated plastic bags at 30°C for 32 hrs. In the products, the proteolytic activity (pH 3, 5 and 7), glucosamine, total protein and free amino acids levels, as well as protein in vitro bioavailability and degree of protein hydrolysis were obtained., Results: The significant correlation was found between glucosamine content and proteolytic activity in grass pea seeds fermented with Rhizopus or Aspergillus. The activities of Rhizopus proteases were higher than Aspergillus ones, which corresponded with the degree of seed protein hydrolysis. Both strains showed the highest activity of protease at pH 3. Tempeh made with pure culture of Rhizopus had 37% protein of 69% in-vitro bioavailability. Mixed-culture fermentation improved nutritional parameters of products only when the dose of Aspergillus spores in the inoculum was equal and lower than that of Rhizopus. This process resulted in higher in-vitro bioavailability of protein, slightly more efficient protein hydrolysis and higher level of free amino acids, as compared to standard tempeh., Conclusions: The activity of A. oryzae in tempeh-type fermentation is beneficial as long as it does not dominate the activity and/or growth of Rhizopus strain.

Abstract Solid-state fermentation of plant materials with food grade moulds is considered a method of obtaining bioactive food products and additives. However, the use of quinoa seeds as a substrate in such a process has not been thoroughly studied to date. In this paper, extended fermentation with Rhizopus oligosporus , Aspergillus oryzae and Neurospora intermedia (tempe, koji and oncom moulds, respectively) was performed in order to enhance the antioxidant potential of coloured quinoa (as measured by the total soluble phenols, ABTS˙+ and ˙OH scavenging activities, and the reducing power). The most efficient of the examined strains was Rhizopus , which caused an average improvement in the aforementioned qualities of 220% (black seeds) and 129% (red seeds), as compared to pre-cooked seeds. Four-day fermentation with Rhizopus resulted in a drastically enhanced amount of vanillin in the free phenolic fraction (130-fold in black quinoa seeds). However, the overall level of free and bound phenolics (as measured by the HPLC-DAD-ESI-TOF-MS method) in the material decreased. Both total peptides and individual free amino acid levels were significantly increased, which corresponded with the high antioxidant potential of the material. The fermented quinoa was also significantly enriched with total dietary fibre with dominant insoluble fraction. Highlights • Quinoa seed antioxidant potential increases after fungal fermentation. • Rhizopus is more effective than Neurospora and Aspergillus. • R. oligosporus activity lowers total phenolics in quinoa. • Antioxidant activity of fermented quinoa is associated with protein hydrolysis. • Fermented quinoa can be a potential bioactive food ingredient. [ABSTRACT FROM AUTHOR]

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 withRhizopus oligosporus. Fair buckwheat groats were characterised by the highest level of phytate (18.3 µmol/g), with 54% share of InsP6fraction. 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 (InsP6-5) 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)P5and Ins(1,2,6)P3– confirmed that the dominant phytase activity could be attributed to the presence of microbial 3-phytases fromR. oligosporous. [ABSTRACT FROM AUTHOR]

The influence of fermentation with Rhizopus oligosporus tempe mold (DSM 1964 or ATCC 64063 strain) on the antioxidant potential of flaxseed oil cake was studied. Solid-state fermentation (SSF) process resulted in the slight increase in proteins and the significant loss of lipids. Even 48 h, the shortest fermentation period, caused the significant increase in phenolic content (13-85%), radical scavenging activity (about twofold higher against DPPH•) and reducing power (by 20-30%). Prolongation of the fermentation by 24 or 48 h resulted in further enhancement of antioxidant capacity. The addition of fermented product (ATCC 64063, 96 h) to yoghurt caused twofold increase in its protein content. The amounts of proteins and antiradical compounds released after the in vitro digestion were higher, as compared with yoghurt alone (by 20 and 40%, respectively). These results allow to consider the fermented flaxseed oil cake as a valuable food additive. Practical Applications Solid-state fermentation tempe type is the traditional method of raw materials processing in order to improve the nutritional and organoleptic properties of food, which is often accompanied by their enrichment in the nonenzymatic antioxidants. Flaxseed oil cake fermentation with tempe mold Rhizopus oligosporus resulted in obtaining products of enhanced soluble phenolic content, radical scavenging activity and reducing power. Thus, SSF can be an alternative method of the processing of the industrial waste product, namely, flaxseed oil cake, in order to apply it as the potential functional food additive of high antioxidant capacity. [ABSTRACT FROM AUTHOR]

Wheat germ cake (WGC) is a nutritionally valuable by-product of oil production from wheat germ, of broad but not yet fully used potential for food applications. Solid-state fermentation with Rhizopus oligosporus and R. oryzae was tested as a new method of WGC bioprocessing aimed to obtain compact products overgrown with mycelium, characterised by a favourable composition. The best results were obtained after 96-h fermentation. The fermented material contained, on average, 42% more peptides, had 30% higher ABTS˙+ scavenging activity, and 100% higher ˙OH -scavenging activity than the raw substrate. The fermented WGC had, on average, 720 μg/g DM soluble phenolic acids, with a significant share of protocatechuic acid (69%). The fungal activity increased the levels of free protocatechuic acid and p-hydroxybenzoic acid. The fermented WGC was a good source of high-quality protein (28 g/100 g DM) rich in Lys (6.9 g/100 g protein), Phe + Tyr (7.9 g/100g protein) and Leu (7.3 g/100 g protein). The products also contained around 14.5 g/100 g DM of dietary fibre with 60:40 insoluble to soluble fraction ratio. Solid-state fermentation can be considered a new method for increasing the nutritional and bioactive value of WGC, thus extending the possibilities of its application for the food industry. [Display omitted] • Wheat germ cake is a convenient substrate for Rhizopus strains. • Fermentation with Rhizopus enhances the antioxidant activity of wheat germ cake. • Protocatechuic acid and p-hydroxybenzoic acid increase after the fermentation. • Fermented wheat germ cake is a good source of Lys-rich protein and dietary fibre. [ABSTRACT FROM AUTHOR]