Maize Milling By-Products: From Food Wastes to Functional Ingredients Through Lactic Acid Bacteria Fermentation

Overview of the Sustainable Valorization of Using Waste and By-Products in Grain Processing

In an increasingly resource-constrained era, using waste and by-products from grain processing has a wide appeal. This is due to the nutritive value and economic aspects of this process and due to its compatibility with the trend towards more sustainable food systems. Following the fundamentals of circular economy, a current need is the effective utilization of grain waste and by-products for conversion into value-added products in the food industry. The aim of this study is twofold: (1) using bibliometrics and the literature found in various databases, we aim to understand the progress of valorizing grain waste and by-products in human nutrition. The literature within various databases, namely, Google Scholar, Web of Science, and Elsevier Scopus, has been evaluated for its merits and values. (2) We aim to explore knowledge-based strategies by reviewing the literature concerning the possible use of grain waste and by-products for the food processing industry, reducing the burden on virgin raw materials. The review allowed us to unlock the latest advances in upcycling side streams and waste from the grain processing industry.

From Waste to Taste: Application of Fermented Spent Rootlet Ingredients in a Bread System

The process of upcycling and incorporating food by-products into food systems as functional ingredients has become a central focus of research. Barley rootlets (BR) are a by-product of the malting and brewing industries that can be valorised using lactic acid bacteria fermentation. This research investigates the effects of the inclusion of unfermented (BR-UnF), heat-sterilised (BR-Ster), and five fermented BR ingredients (using Weissella cibaria MG1 (BR-MG1), Leuconostoc citreum TR116 (BR-TR116), Lactiplantibacillus plantarum FST1.7 (BR-FST1.7), Lactobacillus amylovorus FST2.11 (BR-FST2.11), and Limosilactobacillus reuteri R29 (BR-R29) in bread. The antifungal compounds in BR ingredients and the impact of BR on dough rheology, gluten development, and dough mixing properties were analysed. Additionally, their effects on the techno-functional characteristics, in vitro starch digestibility, and sensory quality of bread were determined. BR-UnF showed dough viscoelastic properties and bread quality comparable to the baker's flour (BF). BR-MG1 inclusion ameliorated bread specific volume and reduced crumb hardness. Breads containing BR-TR116 had comparable bread quality to BF, while the inclusion of BR-R29 substantially slowed microbial spoilage. Formulations containing BR-FST2.11 and BR-FST1.7 significantly reduced the amounts of sugar released from breads during a simulated digestion and resulted in a sourdough-like flavour profile. This study highlights how BR fermentation can be tailored to achieve desired bread characteristics.

Solid-state fermentation improves the quality of chrysanthemum waste as an alternative feed ingredient

Chrysanthemum waste (CW) is an agricultural and industrial by-product produced during chrysanthemum harvesting, drying, preservation, and deep processing. Although it is nutritious, most CW is discarded, wasting resources and contributing to serious environmental problems. This work explored a solid-state fermentation (SSF) strategy to improve CW quality for use as an alternative feed ingredient. Orthogonal experiment showed that the optimal conditions for fermented chrysanthemum waste (FCW) were: CW to cornmeal mass ratio of 9:1, Pediococcus cellaris + Candida tropicalis + Bacillus amyloliquefaciens proportions of 2:2:1, inoculation amount of 6%, and fermentation time of 10 d. Compared with the control group, FCW significantly increased the contents of crude protein, ether extract, crude fiber, acid detergent fiber, neutral detergent fiber, ash, calcium, phosphorus, and total flavonoids (p < 0.01), and significantly decreased pH and saponin content (p < 0.01). SSF improved the free and hydrolyzed amino acid profiles of FCW, increased the content of flavor amino acids, and improved the amino acid composition of FCW protein. Overall, SSF improved CW nutritional quality. FCW shows potential use as a feed ingredient, and SSF helps reduce the waste of chrysanthemum processing.

Combined Thermomechanical-Biological Treatment for Corn By-Product Valorization into Added-Value Food (Feed) Material

The aim of this study was to apply the combined thermomechanical-biological treatment for corn processing by-product (CPBP) valorization to added-value food and feed material. The mechanical-thermal pre-treatment was performed by applying the extrusion technique. Extruded CPBPs (14, 16, and 18% moisture) were further biodegraded with Lactiplantibacillus plantarum-LUHS122 (Lpl), Liquorilactobacillus uvarum-LUHS245 (Lu), Lacticaseibacillus casei-LUHS210 (Lc), and Lacticaseibacillus paracasei-LUHS244 (Lpa). Acidity parameters, microbial characteristics, sugars concentration, amino and fatty acids profile, biogenic amines (BA), and antibacterial and antifungal properties of CPBP were analyzed. Fermented CPBP had a reduced count of mould/yeast. A significantly lower (p ≤ 0.05) count of total enterobacteria was found in most of the extruded-fermented CPBP. Fermentation of extruded CPBP (moisture of 16 and 18%) increased valine and methionine content. Cadaverine and spermidine were not found after treatment of CPBP, and the lowest content of BA was found in the extruded-fermented (Lpa, moisture 18%) CPBP. Applied treatment had a significant effect on most of the fatty acids. CPBP fermented with Lpl, Lu, and Lpa displayed inhibition properties against 3 of the 10 tested pathogenic/opportunistic bacterial strains. Extruded-fermented (Lu, Lc, and Lpa moisture of 14 and 18%) CPBP showed antifungal activity against Rhizopus. Extruded-fermented (14% moisture, Lpl) CPBP inhibited Rhizopus and Aspergillus fumigatus. In conclusion, combined treatment can improve certain parameters and properties of CPBP in order to produce safer and more nutritious ingredients for food and feed industries.

Recent Developments in Fermented Cereals on Nutritional Constituents and Potential Health Benefits

Fermentation is one of the most economical and safe methods to improve the nutritional value, sensory quality and functional characteristics of raw materials, and it is also an important method for cereal processing. This paper reviews the effects of microbial fermentation on cereals, focusing on their nutritional value and health benefits, including the effects of fermentation on the protein, starch, phenolic compounds contents, and other nutrient components of cereals. The bioactive compounds produced by fermented cereals have positive effects on health regulation. Finally, the future market development of fermented cereal products is summarized and prospected.

Effect of Extrusion or Fermentation on Physicochemical and Digestive Properties of Barley Powder

In this work, the effect of extrusion and fermentation on the physicochemical and digestive properties of barley powder was studied. The results showed that the contents of phenolics, β-glucan, protein, and lipid decreased after extrusion. The contents of nutrients (except lipid) increased after fermentation. Both extrusion and fermentation of barley can lead to the darkening of the color and effectively optimize the palatability by reducing the viscosity. In vitro digestion of starch showed that the content of as rapidly digestible starch increased after extrusion and fermentation. The contents of ferulic acid, 2-hydroxybenzoic acid, and caffeic acid decreased after extrusion, while the contents of chlorogenic acid, p-coumaric acid, and ferulic acid increased after fermentation. Basically, the content of all the phenolic showed an increasing trend after digestion. The antioxidant activity decreased after extrusion and increased after fermentation. Therefore, the nutritional composition and properties of barley powder were changed under the two processing methods.

Quinoa sourdough-based biscuits with high antioxidant activity fermented with autochthonous lactic acid bacteria

AIMS

To evaluate the capacity of autochthonous lactic acid bacteria (LAB) (43) from Andean grains to increase the antioxidant activity (AOA) and total phenolic compounds (TPCs) in quinoa sourdough to select best performing strains to be used as starter cultures in the elaboration of biscuits.

METHODS AND RESULTS

Microbial growth (CFU per g) and pH were evaluated during quinoa dough fermentation. Counts were increased in a range of 0.61-2.97 log CFU per g and pH values between 3.95 and 4.54 were determined after 24 h at 30°C of fermentation. Methanolic (ME) and aqueous (AE) extracts were obtained at the end of fermentation, and free radical scavenging capacity was performed by the DPPH and ABTS methods. ME was selected for further analysis using other methods and TPC quantification. Principal component analysis showed the highest scores of growth, acidification capacity, AOA and TPC for the strains Lc. mesenteroides subsp. mesenteroides CRL 2131 and L. plantarum CRL 1964 and CRL 1973. AOA and TPC in biscuits made with sourdough from these LAB were higher than the acidified and uninoculated controls.

CONCLUSIONS

Autochthonous LAB strains (3) increased the AOA of quinoa-based biscuits.

SIGNIFICANCE AND IMPACT OF THE STUDY

Quinoa sourdough obtained with selected LAB is suitable as an ingredient for bakery foods with improved antioxidant status.

Quinoa Flour, the Germinated Grain Flour, and Sourdough as Alternative Sources for Gluten-Free Bread Formulation: Impact on Chemical, Textural and Sensorial Characteristics

The demand for gluten-free breads has increased in the last years, but important quality and nutritional challenges remain unsolved. This research evaluated the addition of quinoa in whole quinoa grain flour, germinated quinoa flour, and quinoa sourdough, as a functional ingredient in the formulation of a rice flour-based bread. Twenty percent (w/w) of the rice flour was replaced with quinoa flour alternatives in bread formulations. The chemical composition, shelf-life, and sensory attributes of the rice-quinoa breads were analyzed. The addition of quinoa in sourdough resulted in breads with a significantly improved protein content at 9.82%, relative to 2.70% in the control breads. The amino acid content in quinoa sourdough breads also was also 5.2, 4.4, 2.6, 3.0, and 2.1 times higher in arginine, glutamic acid, leucine, lysine, and phenylalanine, respectively, relative to control breads with rice flour only. The addition of quinoa sourdough in rice breads also improved the texture, color, and shelf-life (up to 6 days), and thus they became moderately accepted among consumers. Although the germinated quinoa flour addition also resulted in a higher protein (9.77%) and amino acid content, they had a reduced shelf-life (4 days). Similarly, the addition of quinoa flour resulted in a higher protein content (9.61%), but the breads had poor texture attributes and were the least preferred by the consumers.

Valorization of Vegetable Food Waste and By-Products Through Fermentation Processes

There is a general interest in finding new ways of valorizing fruit and vegetable processing by-products. With this aim, applications of industrial fermentation to improve nutritional value, or to produce biologically active compounds, have been developed. In this sense, the fermentation of a wide variety of by-products including rice, barley, soya, citrus, and milling by-products has been reported. This minireview gives an overview of recent fermentation-based valorization strategies developed in the last 2 years. To aid the designing of new bioprocesses of industrial interest, this minireview also provides a detailed comparison of the fermentation conditions needed to produce specific bioactive compounds through a simple artificial neural network model. Different applications reported have been focused on increasing the nutritional value of vegetable by-products, while several lactic acid bacteria and Penicillium species have been used to produce high purity lactic acid. Bacteria and fungi like Bacillus subtilis, Rhizopus oligosporus, or Fusarium flocciferum may be used to efficiently produce protein extracts with high biological value and a wide variety of functional carbohydrates and glycosidases have been produced employing Aspergillus, Yarrowia, and Trichoderma species. Fermentative patterns summarized may guide the production of functional ingredients for novel food formulation and the development of low-cost bioprocesses leading to a transition toward a bioeconomy model.

Advances on the Valorisation and Functionalization of By-Products and Wastes from Cereal-Based Processing Industry

Cereals have been one of the major food resources for human diets and animal feed for thousands of years, and a large quantity of by-products is generated throughout the entire processing food chain, from farm to fork. These by-products mostly consist of the germ and outer layers (bran) derived from dry and wet milling of the grains, of the brewers' spent grain generated in the brewing industry, or comprise other types obtained from the breadmaking and starch production industries. Cereal processing by-products are an excellent low-cost source of various compounds such as dietary fibres, proteins, carbohydrates and sugars, minerals and antioxidants (such as polyphenols and vitamins), among others. Often, they are downgraded and end up as waste or, in the best case, are used as animal feed or fertilizers. With the increase in world population coupled with the growing awareness about environmental sustainability and healthy life-styles and well-being, the interest of the industry and the global market to provide novel, sustainable and innovative solutions for the management of cereal-based by-products is also growing rapidly. In that respect, these promising materials can be valorised by applying various biotechnological techniques, thus leading to numerous economic and environmental advantages as well as important opportunities towards new product development (NPD) in the food and feed industry and other types such as chemical, packaging, nutraceutical (dietary supplements and food additives), cosmetic and pharmaceutical industries. This review aims at giving a scientific overview of the potential and the latest advances on the valorisation of cereal-based by-products and wastes. We intended it to be a reference document for scientists, technicians and all those chasing new research topics and opportunities to explore cereal-based by-products through a circular economy approach.

Teff Type-I Sourdough to Produce Gluten-Free Muffin

The increasing number of persons following a gluten-free (GF) diet and the need for healthy and natural products are forcing researchers and industries to provide gluten-free products with high nutritional value. Here, a biotechnological approach combining the use of teff flour and type-I sourdough has been proposed to produce GF muffins with nutritional benefits. Teff-sourdough was prepared and propagated following the traditional daily refreshment procedure until the biochemical stability was achieved. The sourdough, dominated by Lactiplantibacillus plantarum, Limosilactobacillus fermentum and Saccharomyces cerevisiae strains, was used to produce muffins at three different levels (up to 15%, wt/wt) of fortification, achieving several positive effects on the nutritional properties of the products. The use of teff flour led to high content of fiber (>3 g/100 g) and proteins (>6 g/100 g) in muffins achieving the nutritional requirements for the healthy claims "source of fiber" and "rich in protein". Thanks to their metabolic traits, sourdough lactic acid bacteria caused the increase of the total free amino acids (TFAA, up to 1000 mg/kg, final concentration) and phytic acid decrease (50% lower than control), which positively affect the nutritional properties of the products. Besides, high in vitro protein digestibility (IVPD, 79%) and low starch hydrolysis rate (HI, 52%) characterized the fortified muffins. Muffins also presented high in vitro antioxidant (56%) and mold-inhibitory activities, potentially contributing to an extended shelf-life of the products.

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.

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.

Quinoa pasta fermented with lactic acid bacteria prevents nutritional deficiencies in mice

In recent years, quinoa (Chenopodium quinoa Willd), an ancestral crop of the Andean region of South America, has gained worldwide attention due to its high nutritional value. This grain is a good source of several vitamins and minerals; however, their bioavailability is decreased by the presence of antinutritional factors such as phytic acid. These compounds can be reduced using lactic acid bacteria (LAB), that have a GRAS (Generally Recognized as Safe) status and have traditionally been associated with food fermentation due to their biosynthetic capacity and metabolic versatility. The objective of this study was to evaluate the effectiveness of a pasta made with quinoa sourdough fermented by L. plantarum strains producing vitamins B₂ and B₉ and phytase to prevent vitamins and minerals deficiency using an in vivo mouse model. The results showed that the pasta fermented with the mixed culture containing L. plantarum CRL 2107 + L. plantarum CRL 1964 present increased B₂ and B₉ levels in mice blood. Likewise, higher concentrations of P, Ca⁺², Fe⁺², Mg⁺² (18.75, 10.70, 0.37, 4.85 mg/dL, respectively) were determined with respect to the deficient group (DG) (9.85, 9.90, 0.26, 3.34 mg/dL, respectively). Hematological studies showed an increase in hemoglobin (14.4 ± 0.6 g/dL), and hematocrit (Htc, 47.0 ± 0.6%) values, compared to the DG (Hb: 12.6 ± 0.5 g/dL, Hto: 39.9 ± 1.1%). Furthermore, histological evaluations of the intestines showed an increase of the small intestine villi length in this latter group. The results allow us to conclude that bio-enrichment of quinoa pasta using LAB could be a novel strategy to increase vitamin and minerals bioavailability in cereal/pseudocereal - derived foods.

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.