Solid-State Fermented Flaxseed Oil Cake of Improved Antioxidant Capacity as Potential Food Additive

Abstract

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 APPLICATIONSSolid-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.

Fermentation with Edible Rhizopus Strains to Enhance the Bioactive Potential of Hull-Less Pumpkin Oil Cake

“…The prolongation of the incubation time (up to 72 and 96 h) did not further improve the activity of the material, and it even had the opposite effect in the case of two strains (RP 0.5 values increased by over 30% (DSM 1964) and over 70% (ATCC 64063), as compared to the material fermented for 48 h). This tendency is different than the one observed during the fermentation of flaxseed oil cake with ATCC 64063 and DSM 1964, where the longer incubation time (72 h-144 h) was generally more effective than a two-day process [19].…”

“…The effect of tempe-type fermentation on the˙OH scavenging ability of plant materials (flaxseed oil cake, quinoa seeds, buckwheat groats) observed in our earlier experiments was positive [19][20][21]. However, the prolongation of the incubation (up to 144 h) was not effective in the case of flaxseed oil cake fermentation with R. oligosporus DSM 1964 and ATCC 64063 [19]. A result similar to the one observed in the present study was previously reported for sugared black tea fermented with kombucha ('tea fungus'-a symbiotic association of acetic acid bacteria and yeasts), where the˙OH-scavenging activity decreased, while the DPPH˙-scavenging activity increased as a result of biotreatment [22].…”

“…Nevertheless, it should be stressed that all the fermented products have a significantly higher power against˙OH than the raw pumpkin oil cake (EC 50 0.51-1.13 vs. 1.52). The effect of tempe-type fermentation on the˙OH scavenging ability of plant materials (flaxseed oil cake, quinoa seeds, buckwheat groats) observed in our earlier experiments was positive [19][20][21]. However, the prolongation of the incubation (up to 144 h) was not effective in the case of flaxseed oil cake fermentation with R. oligosporus DSM 1964 and ATCC 64063 [19].…”

“…This strain had been initially recommended for the production of cereal-based tempe due to its scarce amylolytic activity, which ensures that tempe products do not contain undesirable organic acids derived from glucose metabolism [23]. It can be seen, however, that R. oligosporus ATCC 1964 may be considered a versatile strain also suitable for the fermentation of pseudo-cereals, such as quinoa seeds, buckwheat groats [4,21], as well as edible waste from cold-pressed oil extraction, such as pumpkin oil cake (the present study) and flaxseed oil cake [19]. With regard to the ability to increase both the level of soluble phenols and the antioxidant activity of the said substrates, it showed a better potential than other R. oligosporus strains tested here (DSM and especially NRRL), as well as strains that belong to different edible filamentous fungi species used in traditional Asian food fermentations: Rhizopus oryzae (the present study), Aspergillus oryzae-koji strain, and Neurospora intermedia-oncom strain [4].…”

Solid-State Fermentation Reduces Phytic Acid Level, Improves the Profile of Myo-inositol Phosphates and Enhances the Availability of Selected Minerals in Flaxseed Oil Cake

“…It can also be applied as an alternative method for the utilisation of plant by-products. Our previous research showed that the application of R. oligosporus DSM 1964 and ATCC 64063 cultures in the processing of fl axseed oil cake may result in products with enhanced soluble phenolic content and increased antioxidant activity, suitable as functional food additives (17).…”