Fermentation: A Boon for Production of Bioactive Compounds by Processing of Food Industries Wastes (By-Products)

Current Research on Flavor Compounds in Fermented Food Products

Recent advancements in the field of food science have spurred a surge of research focused on unraveling the intricate world of flavor compounds in fermented food products [...].

Trends and challenges of fruit by-products utilization: insights into safety, sensory, and benefits of the use for the development of innovative healthy food: a review

A significant portion of the human diet is comprised of fruits, which are consumed globally either raw or after being processed. A huge amount of waste and by-products such as skins, seeds, cores, rags, rinds, pomace, etc. are being generated in our homes and agro-processing industries every day. According to previous statistics, nearly half of the fruits are lost or discarded during the entire processing chain. The concern arises when those wastes and by-products damage the environment and simultaneously cause economic losses. There is a lot of potential in these by-products for reuse in a variety of applications, including the isolation of valuable bioactive ingredients and their application in developing healthy and functional foods. The development of novel techniques for the transformation of these materials into marketable commodities may offer a workable solution to this waste issue while also promoting sustainable economic growth from the bio-economic viewpoint. This approach can manage waste as well as add value to enterprises. The goal of this study is twofold based on this scenario. The first is to present a brief overview of the most significant bioactive substances found in those by-products. The second is to review the current status of their valorization including the trends and techniques, safety assessments, sensory attributes, and challenges. Moreover, specific attention is drawn to the future perspective, and some solutions are discussed in this report.

An overview of fermentation in the food industry - looking back from a new perspective

Fermentation is thought to be born in the Fertile Crescent, and since then, almost every culture has integrated fermented foods into their dietary habits. Originally used to preserve foods, fermentation is now applied to improve their physicochemical, sensory, nutritional, and safety attributes. Fermented dairy, alcoholic beverages like wine and beer, fermented vegetables, fruits, and meats are all highly valuable due to their increased storage stability, reduced risk of food poisoning, and enhanced flavor. Over the years, scientific research has associated the consumption of fermented products with improved health status. The fermentation process helps to break down compounds into more easily digestible forms. It also helps to reduce the amount of toxins and pathogens in food. Additionally, fermented foods contain probiotics, which are beneficial bacteria that help the body to digest food and absorb nutrients. In today's world, non-communicable diseases such as cardiovascular disease, type 2 diabetes, cancer, and allergies have increased. In this regard, scientific investigations have demonstrated that shifting to a diet that contains fermented foods can reduce the risk of non-communicable diseases. Moreover, in the last decade, there has been a growing interest in fermentation technology to valorize food waste into valuable by-products. Fermentation of various food wastes has resulted in the successful production of valuable by-products, including enzymes, pigments, and biofuels.

Evaluation of biotechnological processing through solid-state fermentation of oilseed cakes on extracts bioactive potential

Oilseed cakes (OC) are natural sources of lignocellulosic biomass, produced every year in large amounts. In addition to their main applications as animal feed, plant or soil fertilizer, and compost, they present enormous potential for being used in biotechnological processes for the obtainment and extraction of valuable bioactive compounds. This work evaluated the effect of solid-state fermentation on the bioactive properties of extracts obtained from the bioprocessing of OC and evaluated the effect of solvents on the recovery of compounds with higher bioactive potential. A general decrease of EC50 values was observed for fermented extracts obtained using a mixture of water/methanol (1:1) as extraction solvent. A decrease in the minimum inhibitory concentration was observed for fermented water extracts compared to non-fermented. Additionally, growth inhibition of Listeria monocytogenes was observed when using aqueous methanolic fermented extracts. These extracts also exhibited a higher percentage of growth reduction against phytopathogenic fungi, and some extracts exhibited increased protection against genotoxic agents such as camptothecin and bisphenol A. It was demonstrated that bioprocessing of OC through SSF is an effective approach to obtaining valuable compounds with bioactive properties for use in the food, pharmaceutical or cosmetic industries.

Valorization of dragon fruit waste to value-added bioproducts and formulations: A review

Owing to the increasing worldwide population explosion, managing waste generated from the food sector has become a cross-cutting issue globally, leading to environmental, economic, and social issues. Circular economy-inspired waste valorization approaches have been increasing steadily, generating new business opportunities developing valuable bioproducts using food waste, especially fruit wastes, that may have several applications in energy-food-pharma sectors. Dragon fruit waste is one such waste resource, which is rich in several value-added chemicals and oils, and can be a renewable resource to produce several value-added compounds of potential applications in different industries. Pretreatment and extraction processes in biorefineries are important strategies for recovering value-added biomolecules. There are different methods of valorization, including green extractions and biological conversion approaches. However, microbe-based conversion is one of the advanced technologies for valorizing dragon fruit waste into bioethanol, bioactive products, pharmaceuticals, and other valued products by reusing or recycling them. This state-of-the-art review briefly overviews the dragon fruit waste management strategies and advanced eco-friendly and cost-effective valorization technologies. Furthermore, various applications of different valuable bioactive components obtained from dragon fruit waste have been critically discussed concerning various industrial sectors. Several industrial sectors, such as food, pharmaceuticals, and biofuels, have been critically reviewed in detail.

Production Enhancement of Bacterial Cellulase Cocktail Using Potato Peels Waste Feedstock and Combination of Water Hyacinth Root and Pea Pod Extract as Natural Nutrient Media: Application in Bioconversion of Potato Peels

Solid wastes are the major contributors in global environmental pollution and their management is the need of urgency towards development of sustainable world. In the present work, solid waste of potato peels has been used as feedstock for fermentation of bacterial cellulase production and substrate for enzymatic hydrolysis via this enzymes cocktail. Additionally, liquid extracts of pea pod and root of water hyacinth wastes have been used to complete nutritional requirements and moisture balance in SSF process during the course of enzyme production. At optimum feedstock concentration of 6.0 g PPW and 10:40 extract-based moisture ratio of WHR and Ppw, Bacillus sp. produced 15 U/gds FP in 18 h, whereas maximum 36 U/gds BGL and 42 U/gds EG have been recorded in 24 h of SSF. Temperature 35 °C and pH 5.5 were optimum for enzyme production while the produced enzyme was thermally stable upto 30 h at 35 °C with 100% pH stability upto 14 h and 77% relative activity at 34 h. The optimized bacterial enzymes have been used for bioconversion of PPW biomass and 26 g/L glucose has been recorded at a hydrolytic temperature of 50 °C and pH 5.0. The study may have feasible promising scope in cellulosic biorefineries and waste management.

Recovery of agricultural waste biomass: A path for circular bioeconomy

Circular bio-economy is a significant approach to resolving global issues elevated by environmental pollution. The generation of bioenergy and biomaterials can withstand the energy-environment connection as well as substitute petroleum-based materials as the feed stock production, thereby contributing to a cleaner and low-carbon-safe environment. Open discarding of waste is a major cause of environmental pollution in developing and under developed countries. Agricultural bio-wastes are obtained through various biological sources and industrial processing, signifying a typical renewable source of energy with ample nutrients and readily biodegradable organic substances. These waste materials are competent to decompose under aerobic and anaerobic conditions. The projected global population, urbanization, economic development, and changing production and consumption behavior result in bounteous bio-waste production. These bio-wastes mainly contain starch, cellulose, protein, hemicellulose, and lipids, which can operate as low-cost raw materials to develop new value-added products. Thus, this review discussed specifically the agricultural waste and valorization processes used to convert this waste into value-added products (biofuel, enzymes, antibiotics, ethanol and single cell protein). These value added products are used in the supply chain and enhance the overall performance of agriculture waste management, execution of circular bio-economy has attained significant importance and it explains a closed-loop system in which the potential resources remain in the loop, allowing them to be sustained into a new value.

In Vitro Evaluation of Antioxidant and Protective Potential of Kombucha-Fermented Black Berry Extracts against H(2)O(2)-Induced Oxidative Stress in Human Skin Cells and Yeast Model

The fruits of R. nigrum L., A. melanocarpa Michx., and V. myrtillus L. are well-known natural plant materials with proven antioxidant activity. This work attempts to compare the antioxidant properties of extracts of these plants and ferments obtained during their fermentation using a consortium of microorganisms referred to as kombucha. As part of the work, a phytochemical analysis of extracts and ferments was carried out using the UPLC-MS method and the content of the main components was determined. The antioxidant properties of the tested samples and their cytotoxicity were assessed with the use of DPPH and ABTS radicals. The protective effect against hydrogen peroxide-induced oxidative stress was also assessed. The possibility of inhibiting the increase in the intracellular level of reactive oxygen species was carried out on both human skin cells (keratinocytes and fibroblasts) and the yeast Saccharomyces cerevisiae (wild-type strains and sod1Δ deletion mutants). The conducted analyses showed that the ferments obtained are characterized by a greater variety of biologically active compounds; in most cases they do not cause a cytotoxic effect, show strong antioxidant properties, and can reduce oxidative stress in both human and yeast cells. This effect depends on the concentration used and the fermentation time. The results obtained indicate that the tested ferments can be considered as an extremely valuable raw material protecting cells against the negative effects of oxidative stress.

Production, characterization and techno-economic evaluation of Aspergillus fusant L-asparaginase

Protoplast fusion is one of the most reliable methods of introducing desirable traits into industrially-promising fungal strains. It harnesses the entire genomic repertoire of fusing microorganisms by routing the natural barrier and genetic incompatibility between them. In the present study, the axenic culture of a thermo-halotolerant strain of Aspergillus candidus (Asp-C) produced an anti-leukemic L-asparaginase (L-ASNase) while a xylan-degrading strain of Aspergillus sydowii (Asp-S) produced the acrylamide-reduction type. Protoplast fusion of the wild strains generated Fusant-06 with improved anti-leukemic and acrylamide reduction potentials. Submerged fed-batch fermentation was preferred to batch and continuous modes on the basis of impressive techno-economics. Fusant-06 L-ASNase was purified by PEG/Na⁺ citrate aqueous two-phase system (ATPS) to 146.21-fold and global sensitivity analysis report revealed polymer molecular weight and citrate concentration as major determinants of yield and purification factor, respectively. The enzyme was characterized by molecular weight, amino acid profile, activity and stability to chemical agents. Michaelis-Menten kinetics, evaluated under optimum conditions gave K_m, V_max, K_cat, and K_cat/K_m as 6.67 × 10^-5 M, 1666.67 µmolmin^-1 mg^-1 protein, 3.88 × 10⁴ min^-1 and 5.81 × 10⁸ M^-1.min^-1 respectively. In-vitro cytotoxicity of HL-60 cell lines by Fusant-06 L-ASNase improved significantly from their respective wild strains. Stability of Fusant-06 L-ASNase over a wide range of pH, temperature and NaCl concentration, coupled with its micromolar K_m value, confers commercial and therapeutic value on the product. Free-radical scavenging and acrylamide reduction activities were intermediate and the conferred thermo-halo-stability could be exploited for sustainable clinical and food industry applications.

Interspecific protoplast fusion of atmospheric and room-temperature plasma mutants of Aspergillus generates an L-asparaginase hyper-producing hybrid with techno-economic benefits

The axenic culture of Aspergillus candidus (Asp-C) produced an anti-leukemic L-asparaginase while Aspergillus sydowii (Asp-S) produced the acrylamide-reduction type. Upon mutagenesis by atmospheric and room-temperature plasma (ARTP), their individual L-asparaginase activities improved 2.3-folds in each of Ile^-Thr^-Asp-C-180-K and Val^-Asp-S-180-E stable mutants. Protoplast fusion of selected stable mutants generated fusant-09 with improved anti-leukemic activity, acrylamide reduction, higher temperature optimum and superior kinetic parameters. Submerged (SmF) and solid-state fermentation (SSF) types were compared; likewise batch, fed-batch and continuous fermentation modes; and fed-batch submerged fermentation was selected on the basis of impressive techno-economics. Fusant L-asparaginase was purified by PEG/Na⁺ citrate aqueous two-phase system and molecular exclusion chromatography to 69.96 and 146.21-fold, respectively, and characterized by molecular weight, specificity, activity and stability to chemical and physical agents. Michaelis-Menten kinetics, evaluated under optimum conditions gave K_m, V_max, K_cat, and K_cat/K_m as 1.667 × 10^-3 M, 1666.67 µmol min^-1 mg^-1 protein, 645.99 s^-1 and 3.88 × 10⁵ M^-1 s^-1 respectively. In-vitro cytotoxicity of HL-60 cell lines by fusant-09 L-asparaginase improved 3.00 and 18.71-folds from mutants Ile^-Thr^-Asp-C-180-K and Val^-Asp-S-180-E, and from 5.73 and 32.55 from respective original strains. Free-radical scavenging and acrylamide reduction improvements were intermediate. Fusant-09 L-asparaginase is strongly recommended for sustainable economic anti-leukemic and food industry applications.

Biorefinery of Brewery Spent Grain by Solid-State Fermentation and Ionic Liquids

Novel environmentally friendly pretreatments have been developed in recent years to improve biomass fractionation. Solid-state fermentation (SSF) and treatment with ionic liquids show low environmental impact and can be used in biorefinery of biomass. In this work, these processes were assessed with brewery spent grain (BSG). First, BSG was used as a substrate to produce cellulases and xylanases by SSF with the fungi Aspergillus brasiliensis CECT 2700 and Trichoderma reesei CECT 2414. Then, BSG was pretreated with the ionic liquid [N₁₁₁₂OH][Gly] and hydrolyzed with the crude enzymatic extracts. Results showed that SSF of BSG with A. brasiliensis achieved the highest enzyme production; meanwhile, the pretreatment with ionic liquids allowed glucan and xylan fractions to increase and reduce the lignin content. In addition, a mixture of the extracts from both fungi in a ratio of 2.5:0.5 Aspergillus/Trichoderma (v/v) efficiently hydrolyzed the BSG previously treated with the ionic liquid [N₁₁₁₂OH][Gly], reaching saccharification percentages of 80.68%, 54.29%, and 19.58% for glucan, xylan, and arabinan, respectively. In conclusion, the results demonstrated that the BSG biorefinery process developed in this work is an effective way to obtain fermentable sugar-containing solutions, which can be used to produce value-added products.

The Disposition of Bioactive Compounds from Fruit Waste, Their Extraction, and Analysis Using Novel Technologies: A Review

Fruit waste contains several bioactive components such as polyphenols, polysaccharides, and numerous other phytochemicals, including pigments. Furthermore, new financial opportunities are created by using fruit ‘leftovers’ as a basis for bioactivities that may serve as new foods or food ingredients, strengthening the circular economy’s properties. From a technical standpoint, organic phenolic substances have become more appealing to industry, in addition to their application as nutritional supplements or functional meals. Several extraction methods for recovering phenolic compounds from fruit waste have already been published, most of which involve using different organic solvents. However, there is a growing demand for eco-friendly and sustainable techniques that result in phenolic-rich extracts with little ecological impact. Utilizing these new and advanced green extraction techniques will reduce the global crisis caused by fruit waste management. Using modern techniques, fruit residue is degraded to sub-zero scales, yielding bio-based commodities such as bioactive elements. This review highlights the most favorable and creative methods of separating bioactive materials from fruit residue. Extraction techniques based on environmentally friendly technologies such as bioreactors, enzyme-assisted extraction, ultrasound-assisted extraction, and their combination are specifically covered.

Sustainable Food Systems: The Case of Functional Compounds towards the Development of Clean Label Food Products

The addition of natural components with functional properties in novel food formulations confers one of the main challenges that the modern food industry is called to face. New EU directives and the global turn to circular economy models are also pressing the agro-industrial sector to adopt cradle-to-cradle approaches for their by-products and waste streams. This review aims to present the concept of “sustainable functional compounds”, emphasizing on some main bioactive compounds that could be recovered or biotechnologically produced from renewable resources. Herein, and in view of their efficient and “greener” production and extraction, emerging technologies, together with their possible advantages or drawbacks, are presented and discussed. Μodern examples of novel, clean label food products that are composed of sustainable functional compounds are summarized. Finally, some action plans towards the establishment of sustainable food systems are suggested.

Single Cell Protein Production Using Different Fruit Waste: A Review

The single cell protein (SCP) technique has become a popular technology in recent days, which addresses two major issues: increasing world protein deficiency with increasing world population and the generation of substantial industrial wastes with an increased production rate. Global fruit production has increased over the decades. The non-edible parts of fruits are discarded as wastes into the environment, which may result in severe environmental issues. These fruit wastes are rich in fermentable sugars and other essential nutrients, which can be effectively utilized by microorganisms as an energy source to produce microbial protein. Taking this into consideration, this review explores the use of fruit wastes as a substrate for SCP production. Many studies reported that the wastes from various fruits such as orange, sweet orange, mango, banana, pomegranate, pineapple, grapes, watermelon, papaya, and many others are potential substrates for SCP production. These SCPs can be used as a protein supplement in human foods or animal feeds. This paper discusses various aspects in regard to the potential of fruit wastes as a substrate for SCP production.

Dynamic changes in molecular composition of black soldier fly prepupae and derived biomasses with microbial fermentation

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Lactic fermentation was used as unconventional way to valorise black soldier fly prepupae and by-products.

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Black soldier fly biomasses (prepupae, pupuria and adult flies) were characterized before and after fermentation.

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LAB fermentation modified insect protein and lipid but not chitin fraction.

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Fermentation improved BSF biomasses in terms of unsaturated fatty acids and essential amino acids.

Black soldier fly (BSF) is being increasingly used for agro-food by-products valorisation. Adult flies, puparia, and excess of prepupae are the by-products of this process, which could be further valorised. Lactic fermentation of BSF biomasses with two different strains (L. rhamnosus and L. plantarum) has been used for this purpose.

Deep changes in the molecular composition were observed, without significant differences related to the different strains used. The lipid and protein fractions were the most impacted. Fermentation enriched the biomass in monounsaturated and polyunsaturated fatty acids and essential amino acids, significantly improving the nutritional properties of the substrates. Although not particularly marked, a proteolytic activity of lactobacilli was observed on the BSF muscular and cuticular proteins, especially in the samples of adult flies and puparia, where fermentation resulted more effective. Conversely, there was no evidence of chitinolytic activity.

Novel Approaches in the Valorization of Agricultural Wastes and Their Applications

Worldwide, a huge amount of agricultural food wastes and byproducts containing valuable bioactive compounds are generated, especially throughout the entire supply chain. Minimizing food wastes and byproducts is the first option to avoid environmental problems, and to help the economy and the society. Although many countries implement policies to reduce food wastes and byproducts, and different management methods are available to utilize agricultural food wastes, they are still produced annually. Nanotechnological and biotechnological approaches are recently used as novel and green applications to valorize agricultural food wastes and improve their stability and applicability. In this Review, these approaches are covered in detail with given examples. Another valorization way of consumable food waste is using it for functional food production. This Review focuses on specific examples of functional foods with food waste as an ingredient. In addition, the problems and limitations of waste management and valorization methods are investigated, considering future perspectives.

A critical look at challenges and future scopes of bioactive compounds and their incorporations in the food, energy, and pharmaceutical sector

Bioactive compounds refer to secondary metabolites extracted from plants, fungi, microbes, or animals. Besides having pharmacological or toxicological effects on organisms leading to utilization in food and pharmaceutical industries, the discovery of novel properties of such compounds has led to the diversification of their applications, ranging from cosmetics and functionalized biomaterials to bioremediation and alternate fuels. Conventional time-consuming and solvent-intensive methods of extraction are increasingly being replaced by green solvents such as ionic liquids, supercritical fluids, and deep eutectic solvents, as well as non-conventional methods of extraction assisted by microwaves, pulse electric fields, enzymes, ultrasound, or pressure. These methods, along with advances in characterization and optimization strategies, have boosted the commercial viability of extraction especially from agrowastes and organic residues, promoting a sustainable circular economy. Further development of microfluidics, optimization models, nanoencapsulation, and metabolic engineering are expected to overcome certain limitations that restrict the growth of this field, in the context of improving screening, extraction, and economy of processes, as well as retaining biodiversity and enhancing the stability and functionality of such compounds. This review is a compilation of the various extraction and characterization methods employed for bioactive compounds and covers major applications in food, pharmacy, chemicals, energy, and bioremediation. Major limitations and scope of improvement are also discussed.

Evaluation of Cosmetic and Dermatological Properties of Kombucha-Fermented Berry Leaf Extracts Considered to Be By-Products

Leaves of Rubus fruticosus L., Vaccinum myrtillus L., Ribes nigrum L. and Fragaria vesca L. are considered agro-waste of the berry industry, but they can be a rich source of valuable bioactive compounds used in cosmetic industry. In this study, kombucha-fermented and non-fermented extracts were compared in terms of chemical composition and biological activity. Polyphenol compounds were identified by HPLC/DAD/ESI-MS. The antioxidant potential was analyzed by evaluating the scavenging of intracellular free radicals contained in keratinocytes and fibroblasts and by DPPH and ABTS assay, obtaining a higher radical scavenging capacity for the ferments, especially for R. fruticosus and V. myrtillus ferments. Assessment of the cytotoxicity on skin cell lines showed their positive effect on the viability of fibroblasts and keratinocytes (especially for the ferments after 10 days of fermentation). The potential anti-ageing properties were determined by their ability to inhibit the activity of metalloproteinases, obtaining almost 30% inhibition of collagenase and elastase in the case of fermented V. myrtillus. Moreover, when the samples were applied to the skin, the positive effect of ferments on skin hydration and pH was demonstrated, which indicates that kombucha berry leaf extracts may be an innovative cosmetic ingredient.

Comparison of Liquid and Solid-State Fermentation Processes for the Production of Enzymes and Beta-Glucan from Hulled Barley

Solid-state fermentation using hulled barley was carried out to produce enzymes and β-glucan. The one-factor-at-a-time experiments were carried out to determine the optimal composition of the basal medium. The modified synthetic medium composition in liquid-state fermentation was determined to be 70 g/l hulled barley, 0 g/l rice bran, 5 g/l soytone, and 6 g/l ascorbic acid. Optimal pretreatment conditions of hulled barley by solid-state fermentation were evaluated in terms of maximum production of fungal biomass, amylase, protease, and β-glucan, which were 1.26 mg/g, 31310.34 U/g, 2614.95 U/g, and 14.6% (w/w), respectively, at 60 min of pretreatment condition. Thus, the solid-state fermentation process was found to enhance the overall fermentation yields of hulled barley to produce high amounts of enzymes and β-glucan.

Challenges and solutions of extracting value-added ingredients from fruit and vegetable by-products: a review

Every year, huge amounts of fruit and vegetable by-products in the food processing factories are produced. These by-products have great potential to be used for different targets especially the extraction of value-added ingredients. The target of this study is to review the challenges of extraction of value-added ingredients from fruit and vegetable by-products on the industrial scale and to describe current trends in solving these problems. In addition, some strategies such as multi-component extraction as well as application of fermentation before or after the extraction process, and production of biofuel, organic fertilizers, animal feeds, etc. on final residues after extraction of value-added ingredients are discussed in this review paper. In fact, simultaneous extraction of different value-added ingredients from fruit and vegetable by-products can increase the extraction efficiency and reduce the cost of value-added ingredients as well as the final volume of these by-products. After extraction of value-added ingredients, the residues can be used to produce biofuels, or they can be used to produce organic fertilizers, animal feeds, etc. Therefore, the application of several appropriate strategies to treat the fruit and vegetable by-products can increase their application, protect the environment, and improve the food economy.

Biological Approaches for Extraction of Bioactive Compounds From Agro-industrial By-products: A Review

Bioactive compounds can provide health benefits beyond the nutritional value and are originally present or added to food matrices. However, because they are part of the food matrices, most bioactive compounds remain in agroindustrial by-products. Agro-industrial by-products are generated in large quantities throughout the food production chain and can—when not properly treated—affect the environment, the profit, and the proper and nutritional distribution of food to people. Thus, it is important to adopt processes that increase the use of these agroindustrial by-products, including biological approaches, which can enhance the extraction and obtention of bioactive compounds, which enables their application in food and pharmaceutical industries. Biological processes have several advantages compared to nonbiological processes, including the provision of extracts with high quality and bioactivity, as well as extracts that present low toxicity and environmental impact. Among biological approaches, extraction from enzymes and fermentation stand out as tools for obtaining bioactive compounds from various agro-industrial wastes. In this sense, this article provides an overview of the main bioactive components found in agroindustrial by-products and the biological strategies for their extraction. We also provide information to enhance the use of these bioactive compounds, especially for the food and pharmaceutical industries.

Effects of pH and Osmotic Changes on the Metabolic Expressions of Bacillus subtilis Strain 168 in Metabolite Pathways including Leucine Metabolism

Bacillus subtilis is often exposed to diverse culture conditions with the aim of improving hygiene or food quality. This can lead to changes in the volatile metabolite profiles related to the quality of fermented foods. To comprehensively interpret the associated metabolic expressions, changes in intracellular primary and extracellular secondary volatile metabolites were investigated by exposing B. subtilis to an alkaline pH (BP, pH 8.0) and a high salt concentration (BS, 1 M). In particular, B. subtilis was cultured in a leucine-enriched medium to investigate the formation of leucine-derived volatile metabolites. This study observed metabolic changes in several metabolic pathways, including carbohydrate metabolism, amino acid metabolism, fatty acid metabolism, and leucine degradation. The formation of proline (an osmolyte), furans, pyrrole, and monosaccharide sugars (glucose, galactose, and fructose) was enhanced in BS, whereas fatty acid derivatives (ketones and alcohols) increased in BP. In the case of leucine degradation, 3-methyl-butanal and 3-methylbutanol could be salt-specific metabolites, while the contents of 3-methylbutanoic acid and 3-methylbutylacetate increased in BP. These results show culture condition-specific metabolic changes, especially secondary volatile metabolites related to the sensory property of foods, in B. subtilis.

A Comprehensive Review on the Interaction of Milk Protein Concentrates with Plant-Based Polyphenolics

Functional properties and biological activities of plant-derived polyphenolic compounds have gained great interest due to their epidemiologically proven health benefits and diverse industrial applications in the food and pharmaceutical industry. Moreover, the food processing conditions and certain chemical reactions such as pigmentation, acylation, hydroxylation, and glycosylation can also cause alteration in the stability, antioxidant activity, and structural characteristics of the polyphenolic compounds. Since the (poly)phenols are highly reactive, to overcome these problems, the formulation of a complex of polyphenolic compounds with natural biopolymers is an effective approach. Besides, to increase the bioavailability and bioaccessibility of polyphenolic compounds, milk proteins such as whey protein concentrate, sodium caseinate, and milk protein concentrate act as natural vehicles, due to their specific structural and functional properties with high nutritional value. Therefore, milk proteins are suitable for the delivery of polyphenols to parts of the gastrointestinal tract. Therefore, this review reports on types of (poly)phenols, methods for the analysis of binding interactions between (poly)phenols-milk proteins, and structural changes that occur during the interaction.

Production of Bioethanol—A Review of Factors Affecting Ethanol Yield

Fossil fuels are a major contributor to climate change, and as the demand for energy production increases, alternative sources (e.g., renewables) are becoming more attractive. Biofuels such as bioethanol reduce reliance on fossil fuels and can be compatible with the existing fleet of internal combustion engines. Incorporation of biofuels can reduce internal combustion engine (ICE) fleet carbon dioxide emissions. Bioethanol is typically produced via microbial fermentation of fermentable sugars, such as glucose, to ethanol. Traditional feedstocks (e.g., first-generation feedstock) include cereal grains, sugar cane, and sugar beets. However, due to concerns regarding food sustainability, lignocellulosic (second-generation) and algal biomass (third-generation) feedstocks have been investigated. Ethanol yield from fermentation is dependent on a multitude of factors. This review compares bioethanol production from a range of feedstocks, and elaborates on available technologies, including fermentation practices. The importance of maintaining nutrient homeostasis of yeast is also examined. The purpose of this review is to provide industrial producers and policy makers insight into available technologies, yields of bioethanol achieved by current manufacturing practices, and goals for future innovation.

Structural Transformation and Creativity Induced by Biological Agents during Fermentation of Edible Nuts from Terminalia catappa

Terminalia catappa L. (tropical almond) is a nutritious fruit found mainly in the tropics. This study is aimed to establish the naturally biotransformed molecules and identify the probiotic agents facilitating the fermentation. The aqueous extracts from both the unfermented and fermented T. catappa nuts were subjected to gas chromatography/mass spectrometry (GC/MS) analysis. Syringol (6.03%), glutamine (1.71%), methyl laurate (1.79%), methyl palmitate (1.53%), palmitic acid (5.20%), palmitoleic acid (2.80%), and methyl oleate (2.97%) were detected in the unfermented nuts of the T. catappa. Additionally, two of these natural compounds (palmitic acid (4.19%) and palmitoleic acid (1.48%)) survived the fermentation process to emerge in the fermented seeds. The other natural compounds were biotransformed into 2,3-butanediol (1.81%), butyric acid (16.20%), propane-1,3-diol (19.66%), neoheptanol (2.89%), 2-piperidinone (6.63%), palmitoleic acid (1.18%), formamide, n-(p-hydroxyphenethyl)- (2.80%), and cis-vaccenic acid (1.69%) that newly emerged in the fermented seeds. The phytochemical compounds are likely carbon sources for the organisms facilitating the biotransformed molecules and product production. Four (4) potential probiotic bacteria strains, namely, Probt B1a, Probt B2a, Probt B4a, and Probt B4b, were isolated from the fermented nut. Enterococcus faecum, and Enterococcus faecalis were the organisms identified as driving the fermentation of the seeds. All strains were gram-positive, catalase-negative, and non-hemolytic, which suggests their harmless nature. N-(p-hydroxyphenethyl)-) was associated with fermentation for the first time, and neoheptanol was discovered as the main alcoholic molecule formed during the fermentation of the seeds. This fermentation is a handy tool for bio-transforming compounds in raw food sources into compounds with nutritious and therapeutic potentials.

Chitosan-tripolyphosphate nanoparticles designed to encapsulate polyphenolic compounds for biomedical and pharmaceutical applications - A review

Plant-based polyphenols are natural compounds, present in fruits and vegetables. During recent years, polyphenols have gained special attention due to their nutraceutical and pharmacological activities for the prevention and treatment of human diseases. Nevertheless, their photosensitivity and low bioavailability, rapid metabolism and short biological half-life represent the major limitations for their use, which could be overcome by polyphenols encapsulation (flavonoids and non-flavonoids) into chitosan (CS)-tripolyphosphate (TPP) based nanoparticles (NP). In this review, we particularly focused on the ionic gelation method for the NP design. This contribution exhaustively discusses and compares results of scientific reports published in the last decade referring to ionic gelation applied for the protection, controlled and site-directed delivery of polyphenols. As a consequence, CS-TPP NP would constitute true platforms to transport polyphenols, or a combination of them, to be used for the designing of a new generation of drugs or nutraceuticals.

Kinetic modeling and quasi-economic analysis of fermentative glycolipopeptide biosurfactant production in a medium co-optimized by statistical and neural network approaches

This study presents the kinetics of production of a glycolipopeptide biosurfactant in a medium previously co-optimized by response surface and neural network methods to gain some insight into its volumetric and specific productivities for possible scale-up towards industrial production. Significant kinetic parameters including maximum specific growth rate, µmax, specific substrate consumption rate, qs and specific biosurfactant yield, Yp/x were determined from logistic model parameters after comparison with other kinetic models. Results showed that bio-catalytic rates of lipase and urease reached exponential values within the first 12 h of fermentation leading to high specific rates of substrate consumption and bacterial growth. Volumetric biosurfactant production reached significantly high levels during prolonged stationary growth and specific urease activity. This suggests that glycolipopeptide biosynthesis may proceed through stationary phase transpeptidation of the glycolipid base. A high cross-correlation coefficient of 0.950 confirmed that substrate consumption and glycolipopeptide production occurred contemporaneously during the 66-h fermentation. The maximum biosurfactant concentration of 132.52 g/L, µmax of 0.292 h^-1, qp of 1.674 g/gDCW/h, rp of 2.008 g/(Lh) and Yp/x of 4.413 g/g predicted by the selected logistic model and a unit cost of €0.57/g glycolipopeptide in the optimized medium may lead to technical and economic benefits.

Functional Ingredients from Agri-Food Waste: Effect of Inclusion Thereof on Phenolic Compound Content and Bioaccessibility in Bakery Products

Reducing food loss and waste is among the efforts to relieve the pressure on natural resources and move towards more sustainable food systems. Alternative pathways of food waste management include valorization of by-products as a source of phenolic compounds for formulation of functional foods. Bakery products may act as an optimal carrier of phenolic compounds upon fortification. The aim of this paper is to present and discuss the effect that the inclusion of functional ingredients from agri-food waste can have on phenolic content and bioaccessibility in bakery products. To this aim, methods for the recovery of phenolic compounds from agri-food waste are presented, and fortification of bakery products by waste from fruits, vegetables, and seed crops is discussed. Bioaccessibility studies on fortified food products are considered to identify gaps and needs in developing sustainable healthy foods. Fruit and vegetable by-products are among the food wastes mostly valorized as functional ingredients in bakery product formulation. Agri-food waste inclusion level has shown to correlate positively with the increase in phenolic content and antioxidant capacity. Nevertheless, further studies are required to assess bioaccessibility and bioavailability of phenolic compounds in enriched food products to estimate the potential of agri-food waste in promoting human health and well-being.

Bioactivity assessment of exopolysaccharides produced by Pleurotus pulmonarius in submerged culture with different agro-waste residues

Pleurotus spp. are white-rot fungi that utilize different agro-wastes to produce useful biologically active compounds. In this study, exopolysaccharides (EPS) were produced by Pleurotus pulmonarius in submerged culture supplemented with different agro-wastes. Functional groups in EPS were revealed using Fourier Transform-Infrared (FT-IR) spectroscopy. Antimicrobial activity of EPS was tested against microorganisms using agar well diffusion. Scavenging potentials of EPS was tested against 1, 1- diphenyl-2-picryhydrazyl (DPPH), hydroxyl (OH), iron (Fe2+) and nitric oxide (NO) radicals. In vitro prebiotic activity of EPS was carried out. The highest yield (5.60 g/L) of EPS was produced by P. pulmonarius in submerged culture supplemented with groundnut shell (20.0 g/L). The functional groups in EPS were hydroxyl (-OH), methyl (-CH3), ketone (-RCOH) and carbonyl group (-C=O). EPS displayed zones of inhibition (5.00-14.00 mm) against tested microorganisms. Scavenging activity of EPS ranged from 65.70-81.80% against DPPH. EPS supported the growth of Lactobacillus delbrueckii and Streptococcus thermophiles with values ranged from 3.04 × 104-3.40 × 104 cfu/ml and 2.50 × 104-2.81 × 104 cfu/ml, respectively. Submerged culture of P. pulmonarius with addition of agro-wastes enhanced yield of EPS. The EPS exhibited bio-functional properties like antimicrobial, antioxidant and prebiotic activities. Hence, agrowastes can be recycled in submerged fermentation with fungi to produce promising biomaterials for biopharmaceutical applications.

Proximate composition, polyphenols, and antioxidant activity of solid state fermented peanut press cake

The current research was led to assess the influence of solid-state fermentation (SSF) with Aspergillus oryzae (MTCC 3107) on polyphenols, antioxidant activities, and proximate composition from peanut press cake of variety HNG-10. Total phenolic, flavonoid, and tannin contents were calculated for polyphenols quantification whereas DPPH, ABTS, FRAP, and metal chelating assay were performed for antioxidant activity. Quantification of polyphenols was confirmed by High Performance Liquid Chromatography technique. Maximum value of total phenolic, flavonoid, and tannin content was found to be 25.55 µM/g GAE, 101.17 µM/g QE, and 245.33 µg/g TAE, respectively. The highest inhibition of free radicals scavenging was noticed on the 5th day of fermentation after that decreased gradually with the increase of fermentation time. Significant increase in fat, i.e. 7.05-12.80% and protein content i.e. 44.05-49.60% was observed. Significant difference in proximate composition of fermented and non-fermented press cake concluded that the progressive role of fermentation improved or transformed physico-chemical properties of substrates.

Antimicrobial Efficacy of Fruit Peels Eco-Enzyme against Enterococcus Faecalis: An In Vitro Study

Sodium hypochlorite (NaOCl), an effective endodontic irrigant against Enterococcus faecalis (EF), is harmful to periapical tissues. Natural pineapple-orange eco-enzymes (M-EE) and papaya eco-enzyme (P-EE) could be potential alternatives. This study aimed to assess the antimicrobial efficacy of M-EE and P-EE at different concentrations and fermentation periods against EF, compared to 2.5% NaOCl. Fermented M-EE and P-EE (3 and 6 months) at various concentrations were mixed with EF in a 96-well plate incubated for 24 h anaerobically. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of M-EE and P-EE were determined via EF growth observation. EF inhibition was quantitatively measured and compared between different irrigants using the one-way analysis of variance (ANOVA), and different fermentation periods using the independent-samples T-test. M-EE and P-EE showed MIC at 50% and MBC at 100% concentrations. There was no significant difference in antimicrobial effect when comparing M-EE and P-EE at 50% and 100% to 2.5% NaOCl. P-EE at 6 months fermentation exhibited higher EF inhibition compared to 3 months at concentrations of 25% (p = 0.017) and 0.78% (p = 0.009). The antimicrobial properties of M-EE and P-EE, at both 100% and 50% concentrations, are comparable to 2.5% NaOCl. They could therefore be potential alternative endodontic irrigants, but further studies are required.

Vegetable milk as probiotic and prebiotic foods

Vegetable milks are fast gaining attention on the global scale as the possible alternatives due to concerns associated with milk consumption. In particular, issues varying from allergenic constituents and lactose intolerance to social and religious beliefs among consumers have induced an increase in the market demand for vegetable milks. Their concomitant nutritional and bioactive components appraise them of the suitable profile for the food-based carriage and delivery of probiotics. More so, the presence of prebiotics in their natural configuration makes them serviceable for the assurance of the needed probiotic viability, subsequent to their exposure to digestive conditions. On another note, their availability, ease of processing, and cost-effectiveness have been established as other possible rationales behind their adoption. This chapter comprehensively delineates the probiotic and prebiotic food-usage of vegetable milks. Captions related with consumer concerns, processing operations, nutritional and prebiotic constitutions, metabolic interactions during probiotic fermentation, and associated health benefits of vegetable milks are discoursed.

Recent advances on the sustainable approaches for conversion and reutilization of food wastes to valuable bioproducts

The increasing amounts of food wastage and accumulation generated per annum due to the growing human population worldwide often associated with environmental pollution issues and scarcity of natural resources. In view of this, science community has worked towards in finding sustainable approaches to replace the common practices for food waste management. The agricultural and food processing wastes rich in nutrients are often the attractive substrates for the bioconversion for valuable bioproducts such as industrial enzymes, biofuel and bioactive compounds. The sustainable approaches on the re-utilization of food wastes as the industrial substrates for production of valuable bioproducts has meet the goals of circular bioeconomy, results in the diversify applications and increasing market demands for the bioproducts. This review discusses the current practice and recent advances on reutilization of food waste for bioconversion of valuable bioproducts from agricultural and food processing wastes.

Biotransformation of rice and sunflower side-streams by dikaryotic and monokaryotic strains of Pleurotus sapidus: Impact on phenolic profiles and bioactive properties

Fungi are known to modify the properties of lignocellulosic materials during solid-state fermentation (SSF). In this study, agricultural side-streams (sunflower seed hulls, rice husks and rice straw) were used as substrates for SSF with dikaryotic and monokaryotic strains of Pleurotus sapidus. The phenolic profiles of the mentioned substrates were characterized by LC-DAD/ESI-MSⁿ pre- and post- fermentation. Moreover, antioxidant, cytotoxic and antimicrobial activities were screened against oxidizable cellular substrates, tumour and primary cell lines, and different bacteria and fungi, respectively. The concentration of phenolic compounds in the crop side-streams was reduced after fermentation with both strains of the fungus. The fermented extracts also displayed lower antioxidant and cytotoxic activities and had no hepatotoxicity. The antimicrobial activity depended upon the crop side-stream and/or SSF conditions. These results indicate that P. sapidus represent a good candidate to modify the phenolic fraction presents in crop side-streams with a consequent decrease in its bioactivities. However, the SSF with P. sapidus strains play an interesting role in the detoxification of plant materials which can be used for different applications according to the "reduce - reuse - recycle" concept contributing with the sustainable land use and circular economy.

Ellagic Acid Recovery by Solid State Fermentation of Pomegranate Wastes by Aspergillus niger and Saccharomyces cerevisiae: A Comparison

Fermentation in solid state culture (SSC) has been the focus of increasing interest because of its potential for industrial applications. In previous studies SSC of pomegranate wastes by Aspergillus niger has been extensively developed and optimized for the recovery of ellagic acid (EA), a high value bioactive. In this study we comparatively investigated the SSC of powdered pomegranate husks by A. niger and Saccharomyces cerevisiae and evaluated the recovery yields of EA by an ultrasound and microwave-assisted 7:3 water/ethanol extraction. Surprisingly enough, the yields obtained by S. cerevisiae fermentation (4% w/w) were found 5-fold higher than those of the A. niger fermented material, with a 10-fold increase with respect to the unfermented material. The EA origin was traced by HPLC analysis that showed a significant decrease in the levels of punicalagin isomers and granatin B and formation of punicalin following fermentation. Other extraction conditions that could warrant a complete solubilization of EA were evaluated. Using a 1:100 solid to solvent ratio and DMSO as the solvent, EA was obtained in 4% yields from S. cerevisiae fermented husks at a high purity degree. Hydrolytic treatment of S. cerevisiae fermented pomegranate husks afforded a material freed of the polysaccharides components that gave recovery yields of EA up to 12% w/w.

Upgrading the Nutritional Value of Rice Bran by Solid-State Fermentation with Pleurotus sapidus

Solid-state fermentation (SSF) of rice bran (RB) employing the edible fungus Pleurotus sapidus was investigated as a process strategy to improve the nutritional quality of this low-cost and abundant substrate. During fermentation, samples were withdrawn at different time intervals (4, 6, and 10 days) and further analyzed. Established methods were deployed to monitor the changes in nutritional composition (carbohydrates, proteins, ash, and lipids). Additionally, changes in fatty acid composition was studied as a function of culture progress. Results showed that the SSF of rice bran increased total carbohydrates from 36.6% to 50.2%, total proteins from 7.4% to 12.8%, and ash from 7.6% to 11.5%. However, the total lipid content was reduced from 48.5% to 27.8%. The fatty acid (FA) composition of RB included mainly oleic, linoleic, and palmitic acids. Upon fermentation with P. sapidus, small differences were found: linoleic acid and oleic acid content were increased by 0.4% and 1.1%, respectively, while palmitic acid content was reduced by 0.8%. This study demonstrated an improvement in the nutritional quality of RB after fermentation with P. sapidus, since protein, carbohydrates, minerals, and specific FA components were increased. As a whole, our results indicate that fermented rice bran could be used as a high-quality animal feed supplement.

Medium Chain Carboxylic Acids from Complex Organic Feedstocks by Mixed Culture Fermentation

Environmental pressures caused by population growth and consumerism require the development of resource recovery from waste, hence a circular economy approach. The production of chemicals and fuels from organic waste using mixed microbial cultures (MMC) has become promising. MMC use the synergy of bio-catalytic activities from different microorganisms to transform complex organic feedstock, such as by-products from food production and food waste. In the absence of oxygen, the feedstock can be converted into biogas through the established anaerobic digestion (AD) approach. The potential of MMC has shifted to production of intermediate AD compounds as precursors for renewable chemicals. A particular set of anaerobic pathways in MMC fermentation, known as chain elongation, can occur under specific conditions producing medium chain carboxylic acids (MCCAs) with higher value than biogas and broader applicability. This review introduces the chain elongation pathway and other bio-reactions occurring during MMC fermentation. We present an overview of the complex feedstocks used, and pinpoint the main operational parameters for MCCAs production such as temperature, pH, loading rates, inoculum, head space composition, and reactor design. The review evaluates the key findings of MCCA production using MMC, and concludes by identifying critical research targets to drive forward this promising technology as a valorisation method for complex organic waste.