Fermentation of Lactobacillus fermentum NB02 with feruloyl esterase production increases the phenolic compounds content and antioxidant properties of oat bran

In this study, strains producing feruloyl esterase were screened by Oxford Cup clear zones method and by evaluating the ability to decompose hydroxycinnamoyl esters. The strain was identified by 16S rDNA molecular biology. The contents of dietary fiber, reducing sugar, water-extractable arabinoxylans, phytic acid, total phenolics, total flavonoid, phenolic compounds composition, microstructure and antioxidant activity in bran before and after fermentation were studied. Eight strains producing feruloyl esterase were screened, among which strain P1 had the strongest ability to decompose hydroxycinnamoyl esters. The strain was identified and named L. fermentum NB02. Compared with unfermented bran, fermented bran exhibited higher contents of soluble dietary fiber, reducing sugar, water-extractable arabinoxylans, total phenolics, total flavonoid, and lower insoluble dietary fiber and phytic acid content. The dense surface structure of bran was destroyed, forming a porous structure. The release of phenolic compounds increased significantly. L. fermentum NB02 fermentation improved the antioxidant capacity of bran.

Antioxidant and Functional Features of Pre-Fermented Ingredients Obtained by the Fermentation of Milling By-Products

The use of milling by-products as ingredients in food formulations has increased gradually over the past years, due to their well-recognized health properties. Fermentation performed with selected microbial strains or microbial consortia is the most promising way to reduce antinutritional factors of cereals and bran, while increasing their nutritional and functional properties. This work, developed within the BBI project INGREEN, was aimed to study the functional, nutritional and technological features of a pre-fermented ingredient obtained from the fermentation of a mixture of rye bran and wheat germ by a selected microbial consortium composed of yeasts (Kazachstania unispora and Kazachstania servazii) and lactic acid bacteria (Latilactobacillus curvatus) using as reference the unfermented mixture and the same mixture fermented by a baker’s yeast. The selected microbial consortium improved the complexity of the volatile molecules such as acids, alcohols and esters. A better retention of color parameters was maintained compared to the product fermented by a baker’s yeast. In addition, the fermentation by the selected consortium showed a significant increase in short chain fatty acids (more than 5-fold), antioxidant activity (22–24%), total phenol content (53–71%), bioactive peptides (39–52%), a reduction of 20–28% in phytic acid content and an increase in prebiotic activity not only compared to the unfermented product but also compared to the preferment obtained with a baker’s yeast. Overall, the fermentation by the selected microbial consortium can be considered a valuable way to valorize milling by-products and promote their exploitation as food ingredients.

Comparative Study of Raw and Fermented Oat Bran: Nutritional Composition with Special Reference to Their Structural and Antioxidant Profile

Oat bran has gained significant attention among cereal brans owing to its comparatively higher presence of dietary fibers and phytochemicals. The objective of the current research is to personify the nutritional and functional aspects of oat bran after yeast-induced (Saccharomyces cerevisiae) fermentation. For this purpose, a comparative study of raw and fermented oat bran was conducted to investigate the nutritional profile, antioxidant activity and functional characteristics of oat bran. Furthermore, pre- and post-structural variations on fermented bran were determined through scanning electron microscopy (SEM). The results show that crude fat, protein and total dietary fiber (soluble and insoluble) contents were significantly improved after fermentation. Moreover, the post-fermentation value of soluble dietary fiber was increased from 5.01 ± 0.21 to 7.2 ± 0.1%. Antioxidant activity, DPPH-RSA and ferric reducing antioxidant power values of bran samples were also enhanced through fermentation and the anti-nutritional factor, i.e., phytate, was significantly reduced from 1113.3 ± 8.5 to 283.4 ± 3.5 mg/100 g in bran samples after fermentation. Furthermore, the surface morphology of fermented oat bran shows scattering and pores, while raw oat bran shows visible aggregation in SEM micrographs. Water-holding capacity was also enhanced up to 2.11 (5.68%) after fermentation. In conclusion, the post-fermentation results revealed that yeast-induced fermentation enhanced the physicochemical, structural and antioxidant characteristics of oat bran.

Improving accessibility and bioactivity of raw, germinated and enzymatic-treated spelt (Triticum spelta L.) seed antioxidants by fermentation

Lactic acid, alcoholic, combined and spontaneous fermentation of raw, germinated and enzymatic-treated spelt seeds significantly improved the content of extractable and bound phenolics and considerably increased the extractable:bound ratio, and therefore positively affected the accessibility of the spelt antioxidants. The highest extractable and bound individual phenolic contents and in vitro antioxidant activities of extracts were obtained following fermentation of germinated spelt seeds with Saccharomyces cerevisiae, while for enzymatic-treated seeds, Lactobacillus plantarum (alone or with S. cerevisiae) was the most effective. For extractable phenolics, trans-ferulic acid increased the most in yeast-fermented germinated seeds (2922%); for bound phenolics, cis-ferulic acid showed the greatest relative increase in yeast-fermented raw spelt seeds (466%). Spontaneous fermentation of germinated and enzymatic-treated samples decreased intracellular oxidation most effectively, probably due to apigenin derivatives. Cellular uptake of bound hydroxycinnamic acids was significantly higher than that of extractable hydroxycinnamic acids; however, the latter were more efficient in vivo antioxidants.

Wheat Bran Modifications for Enhanced Nutrition and Functionality in Selected Food Products

The established use of wheat bran (WB) as a food ingredient is related to the nutritional components locked in its dietary fibre. Concurrently, the technological impairment it poses has impeded its use in product formulations. For over two decades, several modifications have been investigated to combat this problem. Ninety-three (93) studies (review and original research) published in English between January 1997 and April 2021 reporting WB modifications for improved nutritional, structural, and functional properties and prospective utilisation in food formulations were included in this paper. The modification methods include mechanical (milling), bioprocessing (enzymatic hydrolysis and fermentation with yeasts and bacteria), and thermal (dry heat, extrusion, autoclaving), treatments. This review condenses the current knowledge on the single and combined impact of various WB pre-treatments on its antioxidant profile, fibre solubilisation, hydration properties, microstructure, chemical properties, and technological properties. The use of modified WB in gluten-free, baked, and other food products was reviewed and possible gaps for future research are proposed. The application of modified WB will have broader application prospects in food formulations.

Nutritional Features and Bread-Making Performance of Wholewheat: Does the Milling System Matter?

Despite the interest in stone-milling, there is no information on the potential advantages of using the resultant wholegrain flour (WF) in bread-making. Consequently, nutritional and technological properties of WFs obtained by both stone- (SWF) and roller-milling (RWF) were assessed on four wheat samples, differing in grain hardness and pigment richness. Regardless of the type of wheat, stone-milling led to WFs with a high number of particles ranging in size from 315 to 710 μm), whereas RWFs showed a bimodal distribution with large (>1000 μm) and fine (<250 μm) particles. On average, the milling system did not affect the proximate composition and the bioactive features of WFs. The gluten aggregation kinetics resulted in similar trends for all SWFs, with indices higher than for RWFs. The effect of milling on dough properties (i.e., mixing and leavening) was sample dependent. Overall, SWFs produced more gas, resulting in bread with higher specific volume. Bread crumb from SWF had higher lutein content in the wheat cv rich in xanthophylls, while bread from RWF of the blue-grained cv had a moderate but significantly higher content in esterified phenolic acids and total anthocyanins. In conclusion, there was no relevant advantage in using stone- as opposed to roller-milling (and vice versa).

Effect of the Leavening Agent on the Compositional and Sensorial Characteristics of Bread Fortified with Flaxseed Cake

Health and well-being improvement is currently driving innovation in bread, using a wide variety of value-added compounds as extra ingredients, including food industry by-products in a circular economy concept. In this context, this research aimed at evaluating the effect of the fortification of bread with different percentages of flaxseed cake, comparing two leavening agents: sourdough and baker’s yeast. Sensorial, physicochemical, and nutritional properties, including pH, the main fermentative metabolites, fatty acids, total phenols, antioxidant capacity, and volatile organic compounds were determined for fortified bread. The results showed a significant improvement of nutraceutical profile of the bread fortified with flaxseed cake in a dose-dependent manner. Regardless of the leavening agent, the fortification determined a decrease of n-6:n-3 ratio, reaching the recommended value (<3) already at the 7.5% level. Furthermore, under the same fortification level, sourdough breads showed a higher level of total phenols and antiradical activity than baker’s yeast breads. Sensory profiles were instead deeply influenced by both the fortification percentage and the leavening agents. In conclusion, considering both nutritional and sensory results, the best formulation as a function of leavening agent utilized was defined as 5% and 7.5% when sourdough and baker’s yeast were used, respectively.

High-Value Compounds in Fruit, Vegetable and Cereal Byproducts: An Overview of Potential Sustainable Reuse and Exploitation

Food waste (FW) represents a global and ever-growing issue that is attracting more attention due to its environmental, ethical, social and economic implications. Although a valuable quantity of bioactive components is still present in the residuals, nowadays most FW is destined for animal feeding, landfill disposal, composting and incineration. Aiming to valorize and recycle food byproducts, the development of novel and sustainable strategies to reduce the annual food loss appears an urgent need. In particular, plant byproducts are a plentiful source of high-value compounds that may be exploited as natural antioxidants, preservatives and supplements in the food industry, pharmaceuticals and cosmetics. In this review, a comprehensive overview of the main bioactive compounds in fruit, vegetable and cereal byproducts is provided. Additionally, the natural and suitable application of tailored enzymatic treatments and fermentation to recover high-value compounds from plant byproducts is discussed. Based on these promising strategies, a future expansion of green biotechnologies to revalorize the high quantity of byproducts is highly encouraging to reduce the food waste/losses and promote benefits on human health.

Solid state fermentation by Fomitopsis pinicola improves physicochemical and functional properties of wheat bran and the bran-containing products

Wheat bran was solid state fermented by Fomitopsis pinicola. The results showed that the processing properties were increased by fermentation and the content of total phenol and alkylresorcinols was 5.91 and 1.55 times of the unfermented bran respectively by the 6th day. The total antioxidant capacity was 5.73 times of the unfermented sample by the 4th day. Electronic nose analysis showed that the fermented wheat bran had a special flavor. GC-MS analysis found that 4-ethyl-2-methoxy-phenol was the main flavor substance, which was sharply increased during the fermentation. Furthermore, the textural properties of the dough and bread containing fermented bran were significantly improved. The content of phytic acid in the bread was significantly decreased, while the protein, total phenol and alkylresorcinols contents were significantly increased. Results suggest that solid state fermentation by Fomitopsis pinicola is a promising way to improve wheat bran to a nutritious and flavorful cereal food ingredient.

Exploiting Milling By-Products in Bread-Making: The Case of Sprouted Wheat

This research investigated the effect of sprouting on wheat bran. Bran from un-sprouted (BUW) and sprouted (BSW) wheat were characterized in terms of chemical composition, enzymatic activities, and hydration properties. In addition, the rheological properties (using GlutoPeak, Farinograph, Extensograph, and Rheofermentometer tests) and bread-making performance (color, texture, volume of bread) of wheat doughs enriched in bran at 20% replacement level were assessed. Sprouting process caused a significant decrease in phytic acid (~20%), insoluble dietary fiber (~11%), and water holding capacity (~8%), whereas simple sugars (~133%) and enzymatic activities significantly increased after processing. As regards the gluten aggregation kinetics, the BSW-blend profile was more similar to wheat than BUW-blend, indicating changes in the fiber and gluten interactions. BSW led to a worsening of the mixing and leavening properties, instead, no significant changes in extensibility were observed. Finally, BSW improved bread volume (~10%) and crumb softness (~52%). Exploiting bran from sprouted wheat might be useful to produce bread rich in fiber with enhanced characteristics.

Changes of bioactive compounds in barley industry by-products during submerged and solid state fermentation with antimicrobial Pediococcus acidilactici strain LUHS29

In this study, changes of bioactive compounds (crude protein (CP), crude fat (CF), dietary fiber (DF), fatty acids (FAs), free amino acids (FAAs), phenolic compounds (PCs), biogenic amines (BAs), lignans, and alkylresorcinols) in barley industry by-products (BB) during submerged and solid state fermentation (SSF) with Pediococcus acidilactici were analyzed. It was established that both fermentation conditions reduce the CP and CF content in BB (by 25.8% and 35.9%, respectively) and increase DF content (on average by 25.0%). Fermentation increases the oleic, arachidic, eicosadienoic, behenic, and lignoceric FA in BB samples. The highest total BA content was found in untreated samples (290.6 mg/kg). Solid state fermentation increased the content of the alkylresorcinol C19:0. Finally, collecting data about the changes of these compounds during technological processes is very important, because according to the specific compounds formed during fermentation, further recommendations for by-product valorization and uses in food, pharmaceutical, or feed industries can be suggested.

Microbial consortia involved in fermented spelt sourdoughs: dynamics and characterization of yeasts and lactic acid bacteria

This study aims to describe the native microbiota of fermented spelt, taking into consideration both lactic acid bacteria (LAB) and yeasts, for which little data are available. Five samples of commercial spelt flour were subjected to spontaneous fermentation to obtain a type I sourdough. A total of 186 LAB and 174 yeast isolates were selected at different refreshment steps and subjected to further analyses. Within LAB, coccal isolates constituted 78·5% of the total LAB, with the dominance of Pediococcus pentosaceus. Although documented before as a component, this is the first report of a spelt sourdough fermentation dominated by this homofermentative LAB, characterized by a high acidification rate, ability to utilize a wide range of carbon sources and to grow in high osmolarity conditions. Yeast communities resulted in four dominant species, Saccharomyces cerevisiae, Wickerhamomyces anomalus, Pichia fermentans and Clavispora lusitaniae. This study highlights for the first time the biodiversity and dynamics of yeast communities involved in sourdough fermentation of spelt. Compared to commercial baker's yeast, autochthonous W. anomalus, P. fermentans and S. cerevisiae isolates show a good performance, and their use could be an advantage for their acquired adaptation to the environment, providing stability to the fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: Nowadays, there is a renewed interest in products based on spelt. This 'ancient grain' is a highly nutritional grain; however, its use is limited to bread-making processes, which are not standardized. The low baking and sensory quality of spelt can be overcome through fermentation processes. However, the autochthonous microbiota of spelt sourdough is poorly known. This study highlights the dynamics of microbial communities involved in sourdough fermentation of spelt and provides the basis for the selection of autochthonous cultures, with the aim of improving the nutritional potential of spelt and its rheology and bread-making properties.

Brans from hull-less barley, emmer and pigmented wheat varieties: From by-products to bread nutritional improvers using selected lactic acid bacteria and xylanase

Aiming at meeting the recommendations of the World Health Organization regarding the total fiber daily intake, an integrate biotechnological approach, combining xylanase treatment and lactic acid bacteria fermentation of milling by-products from pigmented wheat varieties, hull-less barley and emmer was proposed. The effects on the biochemical and nutritional features were investigated. Enhanced radical scavenging activity, increased concentrations of free amino acids (up to three times) and peptides and optimal in vitro protein digestibility (up to ca. 87%) value as well as relevant phytic acid degradation were achieved during bran fermentation. The main nutritional features of each matrix were enhanced and distinguished. Fortified breads were characterized by a concentration in total dietary fibers and protein of ca. 7 and 13% of dry matter, respectively. Compared to wheat bread the addition of pre-fermented brans caused a significant increase in protein digestibility (up to 79%), and a relevant decrease of the predicted glycemic index (ca. 8%) of the fortified bread. According to the results, this study demonstrates the potential of xylanase treatment and lactic acid bacteria fermentation to be used as suitable strategy to include bran in breadmaking, meeting both nutritional and sensory requests of modern consumers.

Solid-State Yeast Fermented Wheat and Oat Bran as A Route for Delivery of Antioxidants

The purpose of our study was to evaluate the potential of solid-state yeast fermentation (SSYF) in improving the phenolic acid content and composition, and the antioxidant activity of commercial wheat bran (WB) and oat bran (OB). The ultrasound-assisted methanolic extracts were compared for their total phenolic content (TPC), phenolics composition, and in vitro antioxidant activity in order to study the effect of fermentation time on the chemical profile and activity of bioactive compounds. The comparative analysis revealed significant differences (p < 0.05) between days of fermentation (0 through 6). The highest TPCs were obtained on day 3 for WB (0.84 ± 0.05 mg of gallic acid equivalents [GAE]/g dry weight [DW]), and on day 4 for OB (0.45 ± 0.02 mg GAE/g DW). The highest relative percentage increase in the phenolics concentration of WB was also registered on day 3 (ferulic acid +56.6%, vanillic acid +259.3%, dihydroxybenzoic acids +161.2%, apigenin-glucoside +15.3%); for OB, this was observed on day 4 (avenanthramide 2f +48.5%, ferulic acid +21.2%). Enhanced antioxidant activities were significantly correlated with the highest TPCs. Our results suggest that SSYF may be a useful procedure for enrichment of antioxidants in cereal bran, considering the design of different functional foods and nutraceuticals.

How Fermentation Affects the Antioxidant Properties of Cereals and Legumes

The major role of antioxidant compounds in preserving food shelf life, as well as providing health promoting benefits, combined with the increasing concern towards synthetic antioxidants, has led the scientific community to focus on natural antioxidants present in food matrices or resulting from microbial metabolism during fermentation. This review aims at providing a comprehensive overview of the effect of fermentation on the antioxidant compounds of vegetables, with emphasis on cereals- and legumes- derived foods. Polyphenols are the main natural antioxidants in food. However, they are often bound to cell wall, glycosylated, or in polymeric forms, which affect their bioaccessibility, yet several metabolic activities are involved in their release or conversion in more active forms. In some cases, the antioxidant properties in vitro, were also confirmed during in vivo studies. Similarly, bioactive peptides resulted from bacterial and fungal proteolysis, were also found to have ex vivo protective effect against oxidation. Fermentation also influenced the bioaccessibility of other compounds, such as vitamins and exopolysaccharides, enabling a further improvement of antioxidant activity in vitro and in vivo. The ability of fermentation to improve food antioxidant properties strictly relies on the metabolic activities of the starter used, and to further demonstrate its potential, more in vivo studies should be carried out.

Fermentation Biotechnology Applied to Cereal Industry By-Products: Nutritional and Functional Insights

Cereals are one of the major food sources in human diet and a large quantity of by-products is generated throughout their processing chain. These by-products mostly consist of the germ and outer layers (bran), deriving from dry and wet milling of grains, brewers' spent grain originating from brewing industry, or others originating during bread-making and starch production. Cereal industry by-products are rich in nutrients, but still they end up as feed, fuel, substrates for biorefinery, or waste. The above uses, however, only provide a partial recycle. Although cereal processing industry side streams can potentially provide essential compounds for the diet, their use in food production is limited by their challenging technological properties. For this reason, the development of innovative biotechnologies is essential to upgrade these by-products, potentially leading to the design of novel and commercially competitive functional foods. Fermentation has been proven as a very feasible option to enhance the technological, sensory, and especially nutritional and functional features of the cereal industry by-products. Through the increase of minerals, phenolics and vitamins bioavailability, proteins digestibility, and the degradation of antinutritional compounds as phytic acid, fermentation can lead to improved nutritional quality of the matrix. In some cases, more compelling benefits have been discovered, such as the synthesis of bioactive compounds acting as antimicrobial, antitumoral, antioxidant agents. When used for baked-goods manufacturing, fermented cereal by-products have enhanced their nutritional profile. The key factor of a successful use of cereal by-products in food applications is the use of a proper bioprocessing technology, including fermentation with selected starters. In the journey toward a more efficient food chain, biotechnological approaches for the valorization of agricultural side streams can be considered a very valuable help.

Modifying wheat bran to improve its health benefits

Consumption of wheat bran (WB) has been associated with improved gastrointestinal health and a reduced risk for colorectal cancer, cardiovascular diseases and metabolic disorders. These benefits are likely mediated by a combination of mechanisms, including colonic fermentation of the WB fiber, fecal bulking and the prevention of oxidative damage due to its antioxidant capacities. The relative importance of those mechanisms is not known and may differ for each health effect. WB has been modified by reducing particle size, heat treatment or modifying tissue composition to improve its technological properties and facilitate bread making processes. However, the impact of those modifications on human health has not been fully elucidated. Some modifications reinforce whereas others attenuate the health effects of coarse WB. This review summarizes available WB modifications, the mechanisms by which WB induces health benefits, the impact of WB modifications thereon and the available evidence for these effects from in vitro and in vivo studies.

Evaluation of microbial consortia and chemical changes in spontaneous maize bran fermentation

Sustainable exploitation of agro-industrial by-products has attracted great interest in cereal bran valorization. In this research, a polyphasic approach has been carried out to characterize maize bran at microbiological and chemical level during a sourdough like fermentation process, in order to enhance its technological and nutritional properties. Autochthonous microbiota was isolated at different refreshment steps and subjected to identification and molecular characterization. Fermentation was characterized by a rapid increase in lactic acid bacteria and yeasts, with a co-dominance, at the initial stage, of Weissella spp., Pediococcus spp. and Wickerhamomyces anomalus. At the end of the fermentation, a natural selection was produced, with the prevalence of Lactobacillus plantarum, Lactobacillus brevis and Kazachstania unispora. This is the first time that a specific association between LAB and yeasts is reported, during the maize bran fermentation process. Enzymatic activities related to this microbial consortium promoted a "destructuration" of the fiber fraction, an increase in soluble dietary fiber and a reduction of phytic acid content. Our data also evidenced a noticeable increment in ferulic acid. The results obtained indicate that fermentation processes represent an efficient biotechnological approach to increase nutritional and functional potential of maize bran. Moreover, the characterization of microbiota involved in natural fermentation process will allow the selection of specific biotypes, with appropriate metabolic and enzymatic activities, to conduct "tailored" fermentation processes and improve brans or whole-meal flours from both nutritional and technological points of view.

Phytate/calcium molar ratio does not predict accessibility of calcium in ready-to-eat dishes

BACKGROUND

Phytic acid (PA), a naturally occurring compound of plant food, is generally considered to affect mineral bioavailability. The aim of this study was to investigate the reliability of the PA/calcium molar ratio as a predictive factor of calcium accessibility in composed dishes and their ingredients.

RESULTS

Dishes were chosen whose ingredients were rich in Ca (milk or cheese) or in PA (whole-wheat cereals) in order to consider a range of PA/Ca ratios (from 0 to 2.4) and measure Ca solubility using an in vitro approach. The amounts of soluble Ca in composed dishes were consistent with the sum of soluble Ca from ingredients (three out of five meals) or higher. Among whole-wheat products, bread showed higher Ca accessibility (71%, PA/Ca = 1.1) than biscuits (23%, PA/Ca = 0.9) and pasta (15%, PA/Ca = 1.5), and among Ca-rich ingredients, semi-skimmed milk displayed higher Ca accessibility (64%) than sliced cheese (50%) and Parmesan (38%). No significant correlation between the PA/Ca ratio and Ca accessibility was found (P = 0.077).

CONCLUSION

The reliability of the PA/Ca ratio for predicting the availability of calcium in composed dishes is unsatisfactory; data emphasized the importance of the overall food matrix influence on mineral accessibility. © 2016 Society of Chemical Industry.

Impact of solid state fermentation on nutritional, physical and flavor properties of wheat bran

To improve the nutritional, physical and flavor properties of wheat bran, yeast and lactic acid bacteria (LAB) were used for fermenting wheat bran in solid state. Appearance properties, nutritional properties, microstructure, hydration properties and flavor of raw bran and fermented bran were evaluated. After treatments, water extractable arabinoxylans were 3-4 times higher than in raw bran. Total dietary fiber and soluble dietary fiber increased after solid state fermentation. Over 20% of phytic acid was degraded. Microstructure changes and protein degradation were observed in fermented brans. Water holding capacity and water retention capacity of fermented brans were improved. Results suggest that solid state fermentation is an effective way to improve the properties of wheat brans.