Citric acid production from the integration of Spanish-style green olive processing wastewaters with white grape pomace by Aspergillus niger

Bioactive Components, Applications, Extractions, and Health Benefits of Winery By-Products from a Circular Bioeconomy Perspective: A Review

Significant waste streams produced during winemaking include winery by-products such as pomace, skins, leaves, stems, lees, and seeds. These waste by-products were frequently disposed of in the past, causing resource waste and environmental issues. However, interest has risen in valorizing vineyard by-products to tap into their latent potential and turn them into high-value products. Wine industry by-products serve as a potential economic interest, given that they are typically significant natural bioactive sources that may exhibit significant biological properties related to human wellness and health. This review emphasizes the significance of winery by-product valorization as a sustainable management resource and waste management method. The novelty of this review lies in its comprehensive analysis of the potential of winery by-products as a source of bioactive compounds, extraction techniques, health benefits, and applications in various sectors. Chemical components in winery by-products include bioactive substances, antioxidants, dietary fibers, organic acids, and proteins, all of which have important industrial and therapeutic applications. The bioactives from winery by-products act as antioxidant, antidiabetic, and anticancer agents that have proven potential health-promoting effects. Wineries can switch from a linear waste management pattern to a more sustainable and practical method by adopting a circular bioeconomy strategy. Consequently, the recovery of bioactive compounds that function as antioxidants and health-promoting agents could promote various industries concomitant within the circular economy.

The Optimization of Operating Conditions in the Cross-Flow Microfiltration of Grape Marc Extract by Response Surface Methodology

The recovery of valuable compounds like phenolic compounds and sugars from grape marc extracts implies different steps, including clarification. In this study, a response surface methodology (RSM) was used as a statistical tool to study the effects of operating conditions such as transmembrane pressure (TMP), temperature and feed flow rate on the performance of a microfiltration (MF) monotubular ceramic membrane with a pore size of 0.14 μm in the clarification of grape marc extract from the Carménère variety, as well to optimize the process conditions by implementing the Box-Behnken statistical design. The desirability function approach was applied to analyze the regression model equations in order to maximize the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose in the clarified extract. The optimal operating conditions were found to be 1 bar, 29.01 °C and 5.64 L/min. Under these conditions, the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose resulted in 65.78 L/m2h, 43.73 mg/L, 305.89 mg/L, and 274.85 mg/L, respectively.

Citric Acid: Properties, Microbial Production, and Applications in Industries

Citric acid finds broad applications in various industrial sectors, such as the pharmaceutical, food, chemical, and cosmetic industries. The bioproduction of citric acid uses various microorganisms, but the most commonly employed ones are filamentous fungi such as Aspergillus niger and yeast Yarrowia lipolytica. This article presents a literature review on the properties of citric acid, the microorganisms and substrates used, different fermentation techniques, its industrial utilization, and the global citric acid market. This review emphasizes that there is still much to explore, both in terms of production process techniques and emerging new applications of citric acid.

Upgrading Major Waste Streams Derived from the Biodiesel Industry and Olive Mills via Microbial Bioprocessing with Non-Conventional Yarrowia lipolytica Strains

This study reports the development of a bioprocess involving the valorization of biodiesel-derived glycerol as the main carbon source for cell proliferation of Yarrowia lipolytica strains and production of metabolic compounds, i.e., citric acid (Cit), polyols, and other bio-metabolites, the substitution of process tap water with olive mill wastewater (OMW) in batch fermentations, and partial detoxification of OMW (up to 31.1% decolorization). Increasing initial phenolics (Phen) of OMW-glycerol blends led to substantial Cit secretion. Maximum Cit values, varying between 64.1–65.1 g/L, combined with high yield (YCit/S = 0.682–0.690 g Cit/g carbon sources) and productivity (0.335–0.344 g/L/h) were achieved in the presence of Phen = 3 g/L. The notable accumulation of endopolysaccharides (EPs) on the produced biomass was determined when Y. lipolytica LMBF Y-46 (51.9%) and ACA-YC 5033 (61.5%) were cultivated on glycerol-based media. Blending with various amounts of OMW negatively affected EPs and polyols biosynthesis. The ratio of mannitol:arabitol:erythritol was significantly affected (p < 0.05) by the fermentation media. Erythritol was the major polyol in the absence of OMW (53.5–62.32%), while blends of OMW-glycerol (with Phen = 1–3 g/L) promoted mannitol production (54.5–76.6%). Nitrogen-limited conditions did not favor the production of cellular lipids (up to 16.6%). This study addressed sustainable management and resource efficiency enabling the bioconversion of high-organic-load and toxic waste streams into valuable products within a circular bioeconomy approach.

State of the Art on the Microbial Production of Industrially Relevant Organic Acids

The industrial relevance of organic acids is high; because of their chemical properties, they can be used as building blocks as well as single-molecule agents with a huge annual market. Organic acid chemical platforms can derive from fossil sources by petrochemical refining processes, but most of them also represent natural metabolites produced by many cells. They are the products, by-products or co-products of many primary metabolic processes of microbial cells. Thanks to the potential of microbial cell factories and to the development of industrial biotechnology, from the last decades of the previous century, the microbial-based production of these molecules has started to approach the market. This was possible because of a joint effort of microbial biotechnologists and biochemical and process engineers that boosted natural production up to the titer, yield and productivity needed to be industrially competitive. More recently, the possibility to utilize renewable residual biomasses as feedstock not only for biofuels, but also for organic acids production is further augmenting the sustainability of their production, in a logic of circular bioeconomy. In this review, we briefly present the latest updates regarding the production of some industrially relevant organic acids (citric fumaric, itaconic, lactic and succinic acid), discussing the challenges and possible future developments of successful production.

White Grape Pomace Valorization for Remediating Purposes

The present investigation focuses on a possible alternative to reduce grape pomace’s negative impact on the environment by exploiting its capacities for wastewater remediation. Therefore, three directions are followed: (1) the characterization of white grape byproducts’ antioxidant and antiradical properties; (2) the determination of organophosphorus compound concentration that might be present in the samples; and (3) the evaluation of the possible use for wastewater remediation. The grape pomace was used for obtaining different extracts considering different extraction conditions. The hydroalcoholic extracts have an increased amount of total phenolic content. The lyophilized hydroalcoholic extract showed high total phenolic content (159.52 mg/100 g) and low organophosphorus content (0.257 ± 0.015 nmol). The lowest DPPH antiradical-scavenging activities were obtained for the extracts in ethanol obtained from refrigerated pomace (0.055) and for dried pomace (0.045).

Upgrading wineries to biorefineries within a Circular Economy perspective: An Italian case study

In the challenge of transforming waste into useful products that can be re-used in a circular perspective, Italian wine industry can represent a suitable model for the application of the bioeconomy principles, including the valorisation of the agricultural and food waste. In the present study, a comprehensive environmental assessment of the traditional production of wine was performed and the potentiality of a biorefinery system, based on winery waste and aimed at recovering useful bio-based products, such as grapeseed oil and calcium tartrate, was examined through Life Cycle Assessment (LCA). The wine company "I Borboni", producing Asprinio wine in the Campania Region (Italy), was proposed as a case study. The hotspots of the linear production system were identified and the bottling phase, in particular the production of packaging glass, resulted to contribute to the generation of impacts at 63%, on average, versus 14.3% of the agricultural phase and 22.7% of the vinification phase. The LCA results indicated human carcinogenic toxicity, freshwater eutrophication and fossil resource scarcity impact categories as the most affected ones, with normalized impacts amounting to 9.22E-03, 3.89E-04 and 2.64E-04, respectively. Two side production chains (grapeseed oil and tartrate production) were included and circular patterns were designed and introduced in the traditional production chain with the aim of valorising the winery residues and improving the overall environmental performance. By implementing the circular approach, environmental impacts in the global warming, freshwater eutrophication and mineral resource scarcity impact categories, in particular, resulted three times lower than in the linear system. The results achieved demonstrated that closing the loops in the wine industry, through the reuse of bio-based residues alternatively to fossil-based inputs within the production process, and integrating the traditional production system with new side production chains led to an upgrade of the wineries to biorefineries, towards more sustainable production patterns.

Current trends and possibilities for exploitation of Grape pomace as a potential source for value addition

Grape pomace (GP) is a low-value by-product that contains a significant amount of high value-added products. The huge amount of non-edible residues of GP wastes (seeds, skins, leaves and, stems) produced by wine industries causes' environmental pollution, management issues as well as economic loss. Studies over the past 15-20 years revealed that GP could serve as a potential source for valuable bioactive compounds like antioxidants, bioactive, nutraceuticals, single-cell protein, and volatile organic compounds with an increasing scientific interest in their beneficial effects on human and animal health. However, the selection of appropriate techniques for the extraction of these compounds without compromising the stability of the extracted products is still a challenging task for the researcher. Based on the current scenario, the review mainly summarizes the novel applications of winery wastes in many sectors such as agriculture, pharmaceuticals, cosmetics, livestock fields, and also the bio-energy recovery system. We also summarize the existing information/knowledge on several green technologies for the recovery of value-added by-products. For the promotion of many emerging technologies, the entrepreneur should be aware of the opportunities/techniques for the development of high-quality value-added products. Thus, this review presents systematic information on value-added by-products that are used for societal benefits concerning the potential for human health and a sustainable environment.

Impact of olive mill wastewaters on the physiological behavior of a wild-type new Ganoderma resinaceum isolate

A new wild-type Ganoderma resinaceum isolate was cultivated on glucose-enriched liquid cultures with olive mill wastewaters (OMWs) in initial phenolic compounds concentrations 0.0 (control), 0.5, 0.8, and 1.5 g/l. The effect of the fungus on the reduction of phenolics and color was assessed, whereas biomass production, glucose consumption, intra-cellular (IPS) and extra-cellular (EPS) polysaccharides biosynthesis, antioxidant activity of the biomass, and laccase synthesis were monitored. Results showed that significant phenolic reduction (94.5%) and decolorization (76.5%) occurred, 14.6 g/l of biomass was produced, glucose was almost totally consumed, EPS were produced in sufficient amounts (0.79 g/l), whereas the presence of OMWs enhanced the synthesis of IPS (maximum absolute values 4.0-5.2 g/l corresponding to 35-42% w/w). Kinetic analysis demonstrated that EPS and IPS values fluctuated with time, regardless of the available amount of glucose in the media, showing a maximum in the 17th day of culture. Laccase was highly synthesized in the middle of the fermentation, reaching the maximum value of 14 U/ml. Little growth was however observed at 1.5 g/l phenolics. Strong correlation between total phenolic content and free radical scavenging activity has been noticed in the methanolic extracts of the mycelium. Results strongly suggest the potentiality of G. resinaceum utilization in the OMW waste treatment.

Natural β-Carotene Production by Blakeslea trispora Cultivated in Spanish-Style Green Olive Processing Wastewaters

In the current research, the potential of Spanish-style green olive processing wastewaters (lye and washing waters) exploitation toward natural β-carotene production by Blakeslea trispora was tested for the first time. Mating culture generated by the joint cultivation of the heterothallic fungal strains ATCC 14271 and 14272 in the non-sterile lye and washing waters was able to grow, achieving the phytotoxic hydroxytyrosol degradation by 57.3% and 66.8%, respectively. However, the low sugar and nitrogen content of the streams did not favor carotenogenesis. Alternatively, in the nutrient-enriched effluents, a notable quantity of β-carotene was produced, accounted for 61.2 mg/L (lye) and 64.1 mg/L (washing waters) (82–88% of total carotenoid content). Above all, enriched streams had a noteworthy stimulating effect on the β-carotene synthesis, because both the maximum β-carotene yield per volume of enriched effluents and specific β-carotene production rate were higher when compared with the respective values obtained from trials with synthetic reference medium without added effluents. Hydroxytyrosol and tyrosol showed high stability during the non-sterile process for β-carotene production by B. trispora grown in the enriched effluents. This finding strengthens the potential toward the generation of multiple high-value products, which could lower the natural β-carotene production costs.

Microbial production of value-added bioproducts and enzymes from molasses, a by-product of sugar industry

Molasses is a major by-product of sugar industry and contains 40-60% (w/w) of sugars. The world's annual yield of molasses reaches 55 million tons. Traditionally, molasses is simply discharged or applied to feed production. Additionally, some low-cost and environmentally friendly bioprocesses have been established for microbial production of value-added bioproducts from molasses. Over the last decade and more, increasing numbers of biofuels, polysaccharides, oligosaccharides, organic acids, and enzymes have been produced from the molasses through microbial conversion that possess an array of important applications in the industries of food, energy, and pharmaceutical. For better application, it is necessary to comprehensively understand the research status of bioconversion of molasses that has not been elaborated in detail so far. In this review, these value-added bioproducts and enzymes obtained through bioconversion of molasses, their potential applications in food and other industries, as well as the future research focus were generalized and discussed.

Guirlanda C, A. F. Moura M. Use of the Versatility of Fungal Metabolism to Meet Modern Demands for Healthy Aging, Functional Foods, and Sustainability

Aging-associated, non-transmissible chronic diseases (NTCD) such as cancer, dyslipidemia, and neurodegenerative disorders have been challenged through several strategies including the consumption of healthy foods and the development of new drugs for existing diseases. Consumer health consciousness is guiding market trends toward the development of additives and nutraceutical products of natural origin. Fungi produce several metabolites with bioactivity against NTCD as well as pigments, dyes, antioxidants, polysaccharides, and enzymes that can be explored as substitutes for synthetic food additives. Research in this area has increased the yields of metabolites for industrial applications through improving fermentation conditions, application of metabolic engineering techniques, and fungal genetic manipulation. Several modern hyphenated techniques have impressively increased the rate of research in this area, enabling the analysis of a large number of species and fermentative conditions. This review thus focuses on summarizing the nutritional, pharmacological, and economic importance of fungi and their metabolites resulting from applications in the aforementioned areas, examples of modern techniques for optimizing the production of fungi and their metabolites, and methodologies for the identification and analysis of these compounds.

Green processing and biotechnological potential of grape pomace: Current trends and opportunities for sustainable biorefinery

Grape pomace is a high quality biodegradable residue of the winery industry. It is comprised of grape seed, skin and stalks, and is blessed with substantial quantities of phenols, flavonoids and anthocyanins with high antioxidant potential. Currently, there is huge emphasis on the isolation of bioactive molecules of grape pomace using green technologies such as microwave, ultrasound, supercritical fluids, high voltage discharge, enzymatic methods and other hybrid techniques. The major applications of these bioactives are contemplatedas nutraceuticals and extension in shelf-life of perishable foodstuffs. Alternatively, the crude form of grape pomace residues can be used for the production of energy, biofertilizers, biochar, biopolymers, composites, feed for ruminants and also, mushroom cultivation through microbial processing. This review discusses value-addition to grape pomace through biotechnological interventions and green processing, providing state-of-art knowledge on current scenario and opportunities for sustainability.

Processing Wastewaters from Spanish-Style cv. Chalkidiki Green Olives: A Potential Source of Enterococcus Casseliflavus and Hydroxytyrosol

The purpose of this study was to examine the isolation of indigenous lactic acid bacteria (LAB) with functional properties from Spanish-style cv. Chalkidiki green olive processing wastewaters (GOW). Predominant indigenous LAB could serve as bioaugmentation agents/starter culture for table olives production and protected designation of origin specification. Spontaneous fermentation of fresh GOW over different temperatures (15 °C to 50 °C) and pH values (3.5 to 11.5) for 30 d enabled the isolation/molecular identification of the lactic acid bacterium Enterococcus casseliflavus and the plant-associated bacterium Bacillus amyloliquefaciens subsp. plantarum. E. casseliflavus was found to reduce chemical oxygen demand by 72%. Its resistance to extreme pH values, salinity, and temperature was successfully modeled and the minimum inhibitory concentration of oleuropein against the bacterial growth was determined (0.9 g/L). Furthermore, hydroxytyrosol content was doubled (up to 553 mg/L) after GOW spontaneous fermentation under acidic conditions at 15 °C to 30 °C for 120 d, creating an additional source of input. These results highlight the significance and potential of E. casseliflavus in Spanish-style cv. Chalkidiki green olive processing.

Feasibility of multi-hydrolytic enzymes production from optimized grape pomace residues and wheat bran mixture using Aspergillus niger in an integrated citric acid-enzymes production process

In this study, the potential of the co-generation of hydrolytic enzymes in the biorefinery plant for citric acid fermentation was investigated. Aspergillus niger B60 mycelium along with the solid residue after the recovery of sugars from white pomace (WP') were recycled from citric acid fermentation. A mixture design was used to determine the optimum ternary feedstock mixture composed of WP' (15%), red grape pomace (15%) and wheat bran (70%) that produced the target enzymes with high activities, which were compared to those from pure feedstocks. Maximum carboxymethyl cellulase, polygalacturonase, amylase, xylanase and acid protease activities obtained through solid-state fermentation (120 h, 30 °C) of the feedstock mixture were 668 IU/g, 3,151 IU/g, 1,099 IU/g, 579 IU/g and 204 IU/g (dry mass basis), respectively. The system was successfully simulated in SuperPro Designer. Results showed that the enzymes production process serves as the main contributor to the profitability of the biorefinery plant.

Lipid Production by Yeasts Growing on Commercial Xylose in Submerged Cultures with Process Water Being Partially Replaced by Olive Mill Wastewaters

Six yeast strains belonging to Rhodosporidium toruloides, Lipomyces starkeyi, Rhodotorula glutinis and Cryptococcus curvatus were shake-flask cultured on xylose (initial sugar—S0 = 70 ± 10 g/L) under nitrogen-limited conditions. C. curvatus ATCC 20509 and L. starkeyi DSM 70296 were further cultured in media where process waters were partially replaced by the phenol-containing olive mill wastewaters (OMWs). In flasks with S0 ≈ 100 g/L and OMWs added yielding to initial phenolic compounds concentration (PCC0) between 0.0 g/L (blank experiment) and 2.0 g/L, C. curvatus presented maximum total dry cell weight—TDCWmax ≈ 27 g/L, in all cases. The more the PCC0 increased, the fewer lipids were produced. In OMW-enriched media with PCC0 ≈ 1.2 g/L, TDCW = 20.9 g/L containing ≈ 40% w/w of lipids was recorded. In L. starkeyi cultures, when PCC0 ≈ 2.0 g/L, TDCW ≈ 25 g/L was synthesized, whereas lipids in TDCW = 24–28% w/w, similar to the experiments without OMWs, were recorded. Non-negligible dephenolization and species-dependent decolorization of the wastewater occurred. A batch-bioreactor trial by C. curvatus only with xylose (S0 ≈ 110 g/L) was performed and TDCW = 35.1 g/L (lipids in TDCW = 44.3% w/w) was produced. Yeast total lipids were composed of oleic and palmitic and to lesser extent linoleic and stearic acids. C. curvatus lipids were mainly composed of nonpolar fractions (i.e., triacylglycerols).