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Structural and physicochemical properties of the water-treated bacterial cellulose (BC) which was produced by Komagateibacter sucrofermentans strain DSM 15973T either from a solid inoculum of the bacterial preculture in HS medium (BCS7) or liquid one (BCL7) after 7 days were investigated in this work. BCL7 was generally proved to be superior to BCS7 regarding BC yield and water holding capacity (WHC). BCL1-7 and BCS7 were analyzed by SEM (Scanning Electron Microscope), FT-IR (Fourier Transform Infrared Spectroscopy), XRD (X-ray diffraction), Nitrogen Adsorption-Desorption Isotherms, TG (thermogravimetric) and DTG (differential thermogravimetric) analysis, in order to investigate the structural modifications and physicomechanical properties of the water-treated BC pellicles. Both BC7 exhibited a high moisture content (98.8%) and the water release content for BCL7 of 1000 mL retained ~12 g of water after 100 h. BCL7 exhibited higher wet mass, specific surface area, pore volume and pore size distribution compared to BCS7. BCL showed an IV(a) isotherm and the crystallinity index of both BC7 were similar (about 55%). BC thermograms followed the same trend and BCS7 reveals a 35% residue up to 780oC. Overall, the resulted structural and physicomechanical differences between BCL and BCS pellicles appears that each could be used for different application.

This paper studies the reduction of crystallinity degree (CD) of cellulose treated with starch gel (SG), and the correlation of CD with the fermentation efficiency of cellulose to fuel-grade ethanol. Cellulose bioconversion from wood sawdust, consisting of three processes, was conducted in the same batch (one-step). The XRD and TEM analysis revealed 11% reduction in cellulose CD after its treatment with SG. One-step bioconversion process was performed employing two cell factories (CF) of non-engineered S. cerevisiae. CFs contained non- engineered S. cerevisiae cells covered with either SG entrapping Trichoderma reesei or cellulases prepared in the laboratory and immobilized in SG. The consolidated fermentation of treated cellulose resulted in an increase of bioethanol concentration (60-90%) in 2-day fermentation and the maximum ethanol concentration reached was approximately 5 mL/L (3.95 g/L). The fermentation efficiency for grade-fuel ethanol production was improved by cellulose pretreatment using SG to achieve reduced CD.

In this study, an effort was made to create a model cell factory of Saccharomyces cerevisiae using bacterial cellulose (BC) and Aspergillus awamori for consolidated bioprocessing (CBP) of starch. This work suggested development of a cell factory for consolidated bioprocessing of starch in one bioreactor, performing three bioprocesses, i.e. production of amylolytic enzymes by fungal culture, hydrolysis of starch and fermentation to ethanol production using S. cerevisiae without its genetic modification. The microorganisms were separately immobilized on different amounts of BC and their mixture was used for the fermentation of 5% w/v starch. The mixture of BC/A. awamori and BC/S. cerevisiae was used for starch fermentation both in wet and freeze-dried (lyophilized) form in the same ratio (3:1). A 1.75-fold increase in maximum ethanol production was observed using freeze-dried BC immobilized biocatalysts compared to wet cell factory. The ethanol production yield was examined progressively by the effect of (i) initial ratios of both freeze-dried BC/S. cerevisiae and BC/A. awamori, (ii) different weight of the freeze-dried cell factory and (iii) A. awamori cells concentration, reaching the 82% of the theoretical yield encouraging us to use this cell factory model for further fermentations of starch in higher concentration. Ethanol production of 26.69 mL/L and the maximum ethanol yield (0.42 g ethanol/g starch) or 82% of the theoretical yield was achieved by increasing cells of A. awamori inoculum during its immobilization on BC to 109 cells/mL. The results of this work are satisfactory compared with other systems of starch fermentation from literature. SEM, TEM and FTIR spectra analysis were carried out in order to prove the successful preparation of cell factory. SEM showed the immobilization of cells on the BC netting, and TEM showed on BC fibrils. Finally, a repeated fermentation batch was performed, proving the operational viability and stability of the cell factory. The results indicated that the objective of designed cell factory was successfully performer, and the results of starch fermentation are promising for the development of an innovation in brewing industry. Likewise, these have prospects of their application in White-Biotechnology.

Fruit wastes and side-streams can be used for vinegar production to create added value for the agri-food sector and enhance farmer incomes and local economies. In this study, methods for vinegar production by wild and selected acetic acid bacteria (the quick starter Acetobacter aceti and the acid-resistant Komagataeibacter europaeus), free (FC) and immobilized (IC) on a natural cellulosic carrier, are proposed using sweet wine made from the industrial finishing side-stream (FSS) of Corinthian currants as raw material. The results showed all cultures can produce vinegar with 46.65 ± 5.43 g/L acidity, from sweet FSS wine containing 5.08 ± 1.19% alcohol. The effect of immobilization was more obvious in the case of the selected culture, presenting better acetification efficiency, both fresh and after cold storage for 2 months. The vinegars had an antioxidant capacity of 263.5 ± 8.4 and 277.1 ± 6.7 mg/L (as ascorbic acid) and phenolic content 333.1 ± 12.0 and 222.2 ± 2.9 mg/L (as gallic acid) (for FC and IC, respectively). They also had a rich volatilome (140 compounds identified by SPME GC-MS), with higher percentages of esters identified in vinegars made by IC. The results are encouraging for vinegar production with IC of a mixed A. aceti and K. europaeus culture.

Response surface methodology was used to derive a prediction model for organic acids production by anaerobic acidogenic fermentation of cellobiose, using a mixed culture immobilized on γ-alumina. Three parameters (substrate concentration, temperature, and initial pH) were evaluated. In order to determine the limits of the parameters, preliminary experiments at 37 °C were conducted using substrates of various cellobiose concentrations and pH values. Cellobiose was used as a model sugar for subsequent experiments with lignocellulosic biomass. The culture was well adapted to cellobiose by successive subculturing at 37 °C in synthetic media (with 100:5:1 COD:N:P ratio). The experimental data of successive batch fermentations were fitted into a polynomial model for the total organic acids concentration in order to derive a predictive model that could be utilized as a tool to predict fermentation results when lignocellulosic biomass is used as a substrate. The quadratic effect of temperature was the most significant, followed by the quadratic effect of initial pH and the linear effect of cellobiose concentration. The results corroborated the validity and effectiveness of the model.

The aim of this study was to develop a bioprocess for low temperature fruit wine making from ready-to-use freeze-dried raw materials: sour cherry (Prunus cerasus) juice and the psychrotolerant and alcohol resistant yeast strain Saccharomyces cerevisiae AXAZ-1 immobilized on porous delignified cellulose. The effect of storage time of the freeze-dried raw materials at 4 °C (0, 30, and 60 days) on the fermentation efficiency of the yeast, as well as on the quality of the produced wines was evaluated. Sweet wines (>14% v/v alcohol) were produced without need for extra commercial alcohol addition. The sweet, sour cherry wines produced at 10 °C using the freeze-dried raw materials, were analyzed for their aroma profile by headspace SPME GC–MS analysis as well as for their sensory attributes. All wines had similar aroma characteristics with fresh and fruity (cherry) notes, and high esters content. The fermentation kinetics and the sensory characteristics indicate the potential of the freeze-dried raw materials as a ready-to-use mixture for good quality sour cherry sweet wine making even at low temperatures.

A probiotic biocatalyst was prepared through Lactobacillus plantarum ATCC 14917 immobilization on a prebiotic carrier (delignified wheat bran) and was used for fermentations of pomegranate juice. Initially, pomegranate juice was fermented for 24 h and then was stored for 28 days at 4 °C. The obtained results regarding sugar and organic acid analysis revealed that the probiotic biocatalyst was effective. Ethanol was produced in small amounts (0.4-1% v/v). Total phenolic content and antioxidant activity was greater in the fermented pomegranate juice than in unfermented juice after 24 h of fermentation and over the time span of 28 days. Viability of probiotic cells was well maintained (above 8.65 log cfu/mL) after 24 h of fermentation and during 4 weeks of storage at 4 °C, and it is noteworthy that no pathogens were observed. The strength of viability of probiotic cells can be attributed to the immobilization carrier (delignified wheat bran) that exhibits prebiotic properties providing a protective effect to the cells. Finally, the proposed bioprocess of employing the proposed synbiotic biocatalyst for pomegranate juice fermentation shows great potential for commercialization while sensory evaluation highlights the degree of quality of the produced functional pomegranate beverages.

The aim of this study is the consolidated bioprocessing of lactose into lactic acid and ethanol using non-engineered Cell Factories (CFs). Therefore, two different types of composite biocatalysts (CF1-CF2) based on Saccharomyces cerevisiae with immobilized microorganism or enzyme on starch gel (SG) were prepared for 5% w/v lactose fermentation. In CF1, S. cerevisiae was covered with SG containing Lactobacillus casei, Lactobacillus bulgaricus, Kluyveromyces marxianus CF1a-c. S. cerevisiae/SG-β-galactosidase (CF1d) was also used for simultaneous saccharification and fermentation (SSF) of lactose. In CF2, S. cerevisiae immobilized on tubular cellulose (TC) was covered with SG containing the aforementioned microorganisms (CF2a-c). The wet CF1d resulted in 96% of the theoretical ethanol yield while the wet CF1b and freeze-dried CF2b resulted in 89% of the theoretical lactic acid yield. The repeated batches using the CF2a-c exhibited better results than using CF1a-c. Subsequently, the freeze-dried CF2 as preservative and more manageable were verified for future exploitation of whey.

The anaerobic acidogenic fermentation of wheat straw was studied, after various chemical and microbial pretreatments, namely (a) chemical delignification, (b) hydrolytic pretreatment with T. viride of the chemically delignified straw to enhance the organic acid (OAs) yields in the subsequent acidogenic fermentations, and (c) microbial delignification by P. chrysosporium to enhance the biodegradability of the cellulosic material and avoid the chemical pretreatment. The subsequent anaerobic acidogenesis experiments of the wheat straw samples were carried out using a UASB culture free and immobilised on γ-alumina. Hydrolysis with T. viride was limited and slightly improved the result of the acidogenesis. On the other hand, delignification by P. chrysosporium produced satisfactory results, comparable to those of the chemical delignification process. The optimum substrate moisture content for the microbial delignification was 85%. In all cases the immobilised cells increased the OAs yields during the acidogenic fermentations by about 2-fold. Lactic, acetic and butyric acid were the prevailing OAs produced. The OAs could be then used as structural components of ester-based biofuels similar to biodiesel, an approach that has been recently proposed as a cost-effective and environmentally friendly alternative for 2nd generation biofuels production.

In this study, a novel potential probiotic strain Lactobacillus paracasei K5, previously isolated from traditional Greek Feta cheese and kefir grains, was evaluated as an adjunct culture for industrial white brined cheese production. Targeting industrial applications, apart from free cell cultures, a novel ready‐to‐use freeze‐dried immobilized biocatalyst was prepared. The biocatalyst composed of L. paracaseiK5 cells immobilized on delignified wheat bran prebiotic carrier and was freeze‐dried without cryoprotectants. The adjunct free or immobilized culture was added separately without prior adaptation during white brined cheese manufacture and the produced cheeses were compared with commercial white brined cheeses. Several parameters that affect the acceptability and quality of the cheeses, including microbial populations, physicochemical parameters, volatile by‐products and organoleptic characteristics, were analyzed through 70 days of storage. Results showed that the viability of the adjunct culture added either free or immobilized remained in high levels (7 to 8 log cfu/g) during maturation and storage. In addition, all white brined cheeses with the adjunct probiotic culture showed a sharp decrease in spoilage and pathogenic microorganisms such as enterobacteria, salmonella, staphylococci and coliforms during cheese maturation, especially when compared with the commercial white brined cheeses. Finally, after maturation time exceeded, all cheeses were characterized as safe for human consumption. Cheeses volatile compounds were significantly enhanced by the incorporated immobilized biocatalysts. These findings indicate the potential industrial use of freeze‐dried ready‐to‐use immobilized lactobacilli as reinforcement adjunct cultures for the production of good‐quality functional cheese products. The launch on market of novel foods developed by the incorporation of functional ingredients provides potential benefits to consumers’ diet and new business opportunities for producers. Probiotic food products are one significant category of functional foods. Thus, this study focused on the development of a novel ready‐to‐use freeze‐dried potential probiotic biocatalyst for functional white brined cheese production. The potential industrial application of such biocatalysts is highlighted by their incorporation as adjunct cultures that resulted in good‐quality functional cheeses.

Wheat bran, a common cereal processing by-product, was used as immobilisation carrier for a probiotic Lactobacillus casei strain (L. casei ATCC 393). The immobilised synbiotic biocatalyst was freeze-dried without cryoprotectants and was used as adjunct in industrial Feta cheese making (a). For comparison reasons cheeses were also made by addition of: (b) free freeze dried L. casei cells as adjunct, (c) wheat bran, and (c) no-additions (industrial Feta cheese). In all cases the commercial Feta cheese culture was used as starter. The cheeses made with the synbiotic biocatalyst showed significantly higher cell viabilities during storage (120 days, 4 °C) and higher survival rates at exposure to simulated gastric juice (pH 3.0), compared with the cheeses made with free L. casei cells. The shelf-life of the produced cheeses was estimated by enumeration of spoilage microorganisms such as Staphylococci, Enterobacteria, coliforms, yeasts and fungi. To conclude, wheat bran enhanced the viability of the probiotic cells and significantly affected the production of volatile compounds, indicating, in combination with sensory evaluations, the potential for good-quality Feta-type functional cheese production.

The exploitation of starchy wastes for the production of value-added products and the consolidated bioprocessing (CBP) have a positive environmental and cost-effective impact. For this reason, a cell factory (CF) was employed to perform three bioprocesses in one step (CBP) for alcoholic fermentation of starch without genetic modification. CF is a bilayer biocatalyst consisting of an inner layer of immobilized Saccharomyces cerevisiae on tubular cellulose (TC) and an external layer of immobilized Aspergillus awamori on alginates (ALG). In first, the suggested CF was proved to be more effective compared with co-immobilized S. cerevisiae and A. awamori on ALG beads for starch fermentation. Subsequently, the effect of the (i) S. cerevisiae concentration (g S. cerevisiae/g TC) during its immobilization, (ii) CaCl 2 concentration (% w/v), (iii) form of bilayer CF (wet or freeze-dried) and (iv) freeze-dried CF concentration on 5% (w/v) starch fermentation was examined. It was found that the higher ethanol production (32.17 mL/L), productivity (4.60 mL/L/d) and yield (0.51 g ethanol/g starch) reaching the theoretical one were obtained when the CF in freeze dried form fermented 100 mL of 5% (w/v) starch solution. Finally, two repeated fermentation batches were performed using the best CF. The ethanol yield was decreased during the repeated fermentation batches, but remained in acceptable levels. The successful preparation of CF was verified with FTIR spectroscopy, SEM and TEM analysis. The results indicated that the objective of designing CF was successfully achieved, and the results are promising to be the base for the exploitation of starchy wastes and the development of an innovation in brewing industry by eliminating the malting stage. This CF can be applied as model for different bioprocesses of White Biotechnology, e.g. substituting S. cerevisiae with the appropriate microorganism to produce other metabolites of added value.

Enhanced single cell oil (SCO) production by the oleaginous yeast Lipomyces starkeyi DSM 70296, immobilised on delignified porous cellulose, is reported. Pure glucose media were initially used. The effects of substrate pH and treatment temperature were evaluated, showing that 30°C and pH 5.0 were the optimum conditions for SCO production by the immobilised yeast. The immobilisation technique led to increased lipid accumulation and cell growth by 44% and 8%, respectively, in the glucose media, compared to free cells in suspension. This positive effect was also shown when low concentration mixed agro-industrial waste suspensions were used as substrates, leading to 85% enhanced SCO production in comparison with free cells. Higher fatty acid (HFA) analysis showed that yeast immobilisation led to increased formation of unsaturated HFAs (6%) and reduced saturated HFAs (5%) compared to free cells.

The quality and safety of juices are assured mainly through heat treatments and chemical preservatives. However, there is a growing trend in the food industry for lowering energy and water demands, and the chemicals and additives that may have negative effects οn human health. Following that trend, in the present study, the reduced use of chemical preservatives in orange juice is proposed by using encapsulated sodium benzoate (SB) in tubular cellulose (TC), derived from orange pulp. The effects of SB concentration and contact time on SB encapsulation were evaluated. The use of the wet impregnation method, 12% w/v SB solution and 2 h of contact proved to be ideal for application in the juice industry. The use of starch gel resulted in a more stable composite (TC/SB-SG) with a slower SB delivery, showing its potential for future controlled delivery applications. Furthermore, similar delivery rates of SB in juice were noted at 25 and 2 °C. The TC/SB-SG proved capable of inhibiting the growth and reducing the numbers of spoilage microorganisms (yeasts and lactic acid bacteria). The results of the present study are promising for potential applications; however, more research is needed in order to evaluate the controlled delivery of SB in juice.

Delignified wheat straw was fermented by a mixed bacterial anaerobic culture obtained from a UASB reactor to produce organic acids (OAs). Kissiris was used as immobilization carrier in a 2-compartment 82L bioreactor filled with 17L of fermentation broth for the first 7 fermentation batches and up to 40L for the subsequent batches. The amount of straw used was 30g/L and the temperature was set at 37°C for all experiments. The total OAs reached concentrations up to 17.53g/L and the produced ethanol ranged from 0.3 to 1mL/L. The main OAs produced was acetic acid (6-8g/L) and butyric acid (3-8g/L). The OAs were recovered from the fermentation broth by a downstream process using 1-butanol, which was the solvent with the best recovery yields and also served as the esterification alcohol. The enzymatic esterification of OAs resulted to 90% yield.

The effect of wheat bran ( Triticum aestivum ) as a cell immobilization carrier for probiotic yogurt production on cell viability, composition of volatile compounds and sensory characteristics, was studied. Wheat bran was delignified and separately used as a carrier for the immobilization of Lactobacillus casei ATCC393 and Lactobacillus bulgaricus DSM20081. Both biocatalysts were freeze-dried without the addition of cryoprotectants and were used for yogurt fermentation at 40 °C. Their operational stability was evaluated during successive yogurt fermentation batches until they were inactivated. The yogurts fermented using the immobilized biocatalysts were compared with those fermented with free Lactobacillus cells and with conventional yogurt culture ( Streptococcus thermophilus and L. bulgaricus ). The novel yogurts showed significantly higher cell viabilities during storage at 4 °C. In addition, the immobilized biocatalysts showed higher survival rates during exposure to simulated gastric juice (pH 3.0). The immobilized biocatalysts significantly affected the production of volatile compounds, indicating, in combination with the sensory evaluations, potential for good-quality probiotic yogurt production by freeze-dried ready-to-use immobilized starters.

Cheese whey exploitation in a biorefinery manner is proposed involving anaerobic acidogenesis by a UASB mixed anaerobic culture and alcoholic fermentation by kefir. Both cultures were immobilized on γ-alumina. The produced organic acids (OAs) and ethanol could be esterified to obtain a novel ester-based biofuel similar to biodiesel. During acidogenesis, lactic acid-type fermentation occurred leading to 12 g L −1 total OAs and 0.2 g L −1 ethanol. The fermented substrate was subsequently supplied to a second bioreactor with immobilized kefir, which increased the OAs content (15 g L −1 ), especially lactic acid, and slightly the ethanol concentration (0.3–0.4 g L −1 ). To further increase ethanol concentration, a second experiment was conducted supplying whey firstly to the immobilized kefir bioreactor and then pumping the effluent into the acidogenesis bioreactor, resulting in 40% increase of OAs and 10-fold higher ethanol content. The residual sugar was ∼50% of the initial whey lactose; consequently, future research could result to further increase of ethanol and OAs.

U radu je prikazan razvoj novog tipa piva za tržiste, koje se dobiva vrenjem pri niskoj temperaturi u hladnjaku s pomoću imobiliziranog kvasca. Zamrznuta sladovina te stanice soja kvasca Saccharomyces cerevisiae AXAZ-1, koji je otporan na smrzavanje, imobilizirane su na cijevnom modulu i zasebno upotrijebljene za vrenje pri niskim temperaturama (2, 5 i 7 °C). Ispitan je pozitivan učinak cijevnog modula na vrenje pri niskim temperaturama, te je utvrđeno da smrznute imobilizirane stanice kvasca na cijevnom modulu bitno smanjuju brzinu vrenja u usporedbi sa smrznutim slobodnim stanicama, koje su preporučene za proizvodnju piva kod kuće. Imobilizacija je također povećala otpornost kvasca na niske temperature vrenja, pa se najniža moguća temperatura vrenja spustila s 5 na 2 °C. Pri proizvodnji visokokvalitetnog piva ispitani su sljedeći parametri: utjecaj temperature i početne koncentracije šećera na kinetiku vrenja. Analizom gotovog proizvoda potvrđeno je poboljšanje senzorskih svojstava proizvedenog piva, s niskom koncentracijom diacetila, povećanim udjelom polifenola, te poboljšanim profilom arome i bistroćom. Predloženi postupak proizvodnje piva u hladnjaku može se lako komercijalizirati za kućnu uporabu otapanjem sadržaja dvaju pakiranja, jednog sa suhom sladovinom i drugog sa suhim stanicama kvasca imobiliziranim na cijevnom modulu i otopljenim u vodi., Development of a novel directly marketable beer brewed at low temperature in a domestic refrigerator combined with yeast immobilization technology is presented in this study. Separately, freeze-dried wort and immobilized cells of the cryotolerant yeast strain Saccharomyces cerevisiae AXAZ-1 on tubular cellulose were used in low-temperature fermentation (2, 5 and 7 °C). The positive effect of tubular cellulose during low-temperature brewing was examined, revealing that freeze-dried immobilized yeast cells on tubular cellulose significantly reduced the fermentation rates in contrast to freeze-dried free cells, although they are recommended for home-made beer production. Immobilization also enhanced the yeast resistance at low-temperature fermentation, reducing the minimum brewing temperature value from 5 to 2 °C. In the case of high-quality beer production, the effect of temperature and initial sugar concentration on the fermentation kinetics were assessed. Sensory enrichment of the produced beer was confirmed by the analysis of the final products, revealing a low diacetyl concentration, together with improved polyphenol content, aroma profile and clarity. The proposed process for beer production in a domestic refrigerator can easily be commercialized and applied by dissolving the content of two separate packages in tap water; one package containing dried wort and the other dried immobilized cells on tubular cellulose suspended in tap water.

In the present study, probiotic sour milk was produced by freeze-dried Lactobacillus casei ATCC 393 cells, free or immobilized on wheat bran. Wheat bran was used with and without lignin removal. The aim was to evaluate the possibility to produce sour milk using immobilized probiotic biocatalysts that could be removed after the end of fermentation and be used in a next fermentation batch. The effect of the biocatalysts on product quality was also evaluated during 30 days of storage at 4 °C. The aroma profile, organic acids production, residual sugar content and culture viability were monitored during that period. The immobilized bacteria on wheat bran were better protected in the acidic environment of the sour milk fermentations, compared to free cells. The microbial populations (>7.5 log cfu g−1) were significantly higher in sour milks produced with the immobilized biocatalysts during the 30 day storage, while no growth of pathogenic microorganisms was observed. The microbiological, physicochemical, and sensory characteristics of the sour milks produced using the immobilized biocatalysts, indicated high commercialization potential of these products.

In the present study, a novel potentially probiotic Lactobacillus paracasei strain, previously isolated from dairy products, was evaluated as a starter culture of Feta-type cheese production. Targeting industrial applications, the starter culture was applied as a ready-to-use freeze-dried culture that was either free or immobilized. The immobilized biocatalyst composed of Lactobacillus paracasei K5 cells absorbed within delignified wheat bran prebiotic carrier. All produced cheeses were compared with cheese manufactured by renin enzyme. Several parameters that affect acceptability, quality and shelf-life of Feta-type cheese were investigated, including microbial populations, physicochemical characteristics and cheese volatiles through 90 days of ripening and storage. Survival of L. paracasei K5 remained in high levels (&ge, 6.0 log cfu/g) after the 90th day of cheese production, as recorded by combining microbiological enumeration and strain-specific multiplex PCR analysis. The use of the freeze-dried novel starter culture (free or immobilized) enhanced the aromatic profile of Feta-type cheeses. Finally, the use of the potentially synbiotic immobilized biocatalyst further improved aromatic characteristics of produced cheese and decrease of possible spoilage or pathogenic microorganisms. These findings indicate the potential industrial use of freeze-dried L. paracasei K5 as starter culture for the production of good-quality functional Feta-type cheese.

In the present study 38 lactic acid bacteria strains were isolated from kefir grains and were monitored regarding probiotic properties in a series of established in vitro tests, including resistance to low pH, resistance to pepsin and pancreatin, and tolerance to bile salts, as well as susceptibility against common antibiotics. Among them, the strain SP3 displayed potential probiotic properties. Multiplex PCR analysis indicated that the novel strain belongs to the paracasei species. Likewise, the novel strain (Lactobacillus paracasei SP3) was applied as a starter culture for Feta-type cheese production. Feta-type cheese production resulted in significantly higher acidity, lower pH, reduced counts of coliforms, yeasts and fungi, and improved quality characteristics compared with cheese samples produced with no starter culture. Finally, it is highlighted that the application of the novel strain led to Feta-type cheese production with improved overall quality and sensory characteristics.

This investigation examines the possibility for nitrite chemical preservative to be delivered in meat cured products. Potassium nitrite was encapsulated in delignified leaf celery and spinach and placed on the surface of meat. The delignification of leaf celery and spinach produces edible tubular cellulose (ETC) with 10 fold increased pore volume. The encapsulation and delivery of nitrite using vegetable tubular cellulose has been achieved in both ETC and ETC/Starch gel (SG) composite. Specifically, 43.5% of initially encapsulated potassium nitrite remains in the tubes of ETC/SG composite for a period of 5 days and 56.5% of nitrite is diffused in the meat, reaching a depth of 5 cm. The low delivery of potassium nitrite does not reduce the antibacterial activity of the total amount of nitrite. The controlled delivery of nitrite leads to a substantial reduction in meat microbiological load which was observed for a period of 10 days. Further research is needed, in order to develop the final technology for nitrite delivery in meat and meat products.

This article presents a comprehensive review on hydrolysis and acidogenesis of lignocellulosic waste biomass and makes clear new perspectives in biofuel research. Specifically, the acidogenesis of lignocellulosics and liquid effluent have been discussed extensively with potential goal the production of a new generation biofuel. This new biofuel can be produced through esterification of volatile fatty acids with ethanol (produced simultaneously during the acidogenesis) or/and with another alcohol. That will overcome the major problems faced during bioethanol production and concerns the high energy demand of the bioethanol production plant. Specifically, it was found that the main volatile fatty acids formed are formic, acetic, propionic, butyric, lactic and valeric. Their formation depends on NADH/NAD+ proportion and on conditions such as pH, organic load and chemical composition of the waste is treated. These conditions look to affect microorganisms survival and the formation of predominant acetic, butyric and lactic acid. The use of γ-alumina promotes the formation of volatile fatty acids simultaneously with bio-ethanol.

The aim of this investigation was to study the use of nano/micro-porous cellulosic materials (tubular cellulose, TC) produced by delignification of mango (Magnifera indica L.), sal (Shorea robusta G.) sawdust and rice husk (Oryza sativa L.) in various food bioprocesses. Specifically, the porous structure of TC renders it suitable for use as filter material in continuous cold pasteurization processes as well as biocatalyst (carrier for yeast immobilization) for alcoholic fermentation. Water contaminated with Saccharomyces cerevisiae or Lactobacillus bulgaricus cells was continuously pumped through TC filters. The effect of TC origin, type of contamination and microbial load on the operational stability of the system was assessed. The microbial load removal ranged between 99.9-88.2% and 92–77% for yeast and bacteria, respectively. The system operated efficiently for up to 55 days. Filter regeneration was done with hot water. Scanning electron micrographs showed the entrapment of cells in the TC filters. The TCs were further used as S. cerevisiae immobilization carriers for alcoholic fermentation of grape must and glucose media at 15 °C. Satisfactory fermentation rates, high ethanol content, ethanol productivity, and volatile by-products formation were observed. The TCs showed great potential for water pretreatment and food bioprocessing with simultaneous valorization of lignocellulosic biomass.

Nowadays there has been an increased interest in the development of new functional foods and their incorporation in a healthy diet. Such products and especially probiotics exert a beneficial effect on host gut microbiota after consumption and may be capable to prevent several diseases. Fermented beverages are traditional products that act as vehicles of probiotics in human diet. Many studies the last decades have concluded that the best substrates for the delivery of probiotics are dairy products. However lactose intolerance, high fat and cholesterol, milk allergies and also the growing trend of vegetarianism has promoted the research in the field of non-dairy probiotic products. Therefore this review highlights the recent advances in the field of probiotic beverages both from dairy and non-dairy origin.

A novel continuous preservation process of apple juice using a nano/micro-porous cellulosic material (or “tubular cellulose”, abrrev. TC), is presented in this study. This investigation aims to the development of a non-thermal system for microbial stabilization, avoiding the degradation of food quality caused by heat. TC was used as filter in a packed-bed type bioreactor supplied with commercial apple juice contaminated with Saccharomyces cerevisiae or Lactobacillus plantarum cells at 4 °C. The effect of the filter size on the microbial load removal and chemical/sensory properties of the juice was evaluated. The system presented good operational stability during 55 and 30 days for the removal of yeast and bacteria, respectively. The increase of filter size improved the microbial removal yield and the system effectiveness. The organoleptic parameter values decreased after ΤC regeneration but then reached almost initial levels. The proposed process is a low-cost and promising alternative to existing thermal pasteurization technologies. Industrial relevance Conventional thermal pasteurization treatments are applied industrially for microbial stabilization of foods but significantly affect the organoleptic characteristics of the products. This study evaluated a novel non-thermal preservation method of contaminated apple juice that meets the consumer's demand for less processed products with high nutritional value. Commercial apple juice was contaminated with S. cerevisiae or L. plantarum cells and then was continuously pumped through tubular cellulose. The increased size of the filter leads to improved microbial removal yields. Despite the decrease of volatile compounds and colour at the start up of the process and after each filter regeneration with hot water, almost initial parameter values were achieved as the process evolved. The proposed technology can be a promising alternative of industrial pasteurization techniques for food applications.

Thermal pasteurisation is used for the microbial stabilisation of foods, but this process compromises quality food properties. This study proposes a novel cold preservation method with filtering materials obtained from agricultural by-products. Nano/micro-porous cellulose materials from native corn stalks (NCS), and the material obtained after delignification, were used as filtering materials for the microbial stabilisation of water and orange juice. The optimisation study of NCS and corn stalk tubular cellulose material (CSTC) to remove yeast Saccharomyces cerevisiae and Lactobacillus casei from water in accordance with processing variables was firstly conducted. Optimisation tests demonstrated the influence of cell concentration, filter size and flow rate on filter removal yields. Then the continuous filtration of commercial orange juice was performed for 20 days to remove S. cerevisiae. The results showed that delignified CSTC was an effective filtering material for removing S. cerevisiae and L. casei from water, and it successfully treated commercial contaminated orange juice. Despite juice colour diminishing when the process started and after filter regeneration cycles with hot water, almost initial parameter values were obtained as the process continued. Therefore, the proposed filtering material is a promising low-cost alternative to existing thermal pasteurisation technologies for liquid foods.

An alternative methodology is proposed for low temperature winemaking using freeze-dried raw materials. Pine sawdust was delignified and the received porous cellulosic material was applied as immobilization carrier of the psychrotolerant yeast strain Saccharomyces cerevisiae AXAZ-1. The immobilization of yeast cells was examined and verified by scanning electron microscopy (SEM). The immobilized biocatalyst and high-gravity grape must were separately freeze-dried without cryoprotectants and stored at room temperature (20&ndash, 22 &deg, C) for 3 months. The effect of storage on the fermentation efficiency of the immobilized biocatalyst at low temperatures (1&ndash, 10 &deg, C), as well as on the aromatic characteristics of the produced wines was evaluated. Storage time had no significant effect on the fermentation efficiency of the biocatalyst resulting in most cases in high ethanol production 13.8&ndash, 14.8% v/v. The volatile fraction of the produced wines was examined using headspace solid-phase microextraction (HS-SPME) followed by gas chromatography mass spectrometry (GC/MS). GC-MS/SPME analysis along with the organoleptic evaluation revealed in all produced wines a plethora of fresh and fruit aromatic notes. To conclude, fermentation kinetics and aromatic profile evaluation encourages the production of high-quality sweet wines at low temperatures using pine sawdust (Pinus halepensis) entrapped yeast cells as a promoter.

In the present study, a novel potentially probiotic Lactobacillus paracasei strain, previously isolated from dairy products, was evaluated as a starter culture of Feta-type cheese production. Targeting industrial applications, the starter culture was applied as a ready-to-use freeze-dried culture that was either free or immobilized. The immobilized biocatalyst composed of Lactobacillus paracasei K5 cells absorbed within delignified wheat bran prebiotic carrier. All produced cheeses were compared with cheese manufactured by renin enzyme. Several parameters that affect acceptability, quality and shelf-life of Feta-type cheese were investigated, including microbial populations, physicochemical characteristics and cheese volatiles through 90 days of ripening and storage. Survival of L. paracasei K5 remained in high levels (≥6.0 log cfu/g) after the 90th day of cheese production, as recorded by combining microbiological enumeration and strain-specific multiplex PCR analysis. The use of the freeze-dried novel starter culture (free or immobilized) enhanced the aromatic profile of Feta-type cheeses. Finally, the use of the potentially synbiotic immobilized biocatalyst further improved aromatic characteristics of produced cheese and decrease of possible spoilage or pathogenic microorganisms. These findings indicate the potential industrial use of freeze-dried L. paracasei K5 as starter culture for the production of good-quality functional Feta-type cheese.

The recently isolated Lactobacillus paracasei K5 (a potential probiotic) was immobilized on delignified wheat bran (DWB) and was used to produce a functional pomegranate beverage. Fermentations were carried out for 24 h at different pH values (3.3, 3.6, and 3.9), and the fermented juices were stored for 4 weeks at 4 °C. In all cases, the immobilized biocatalyst was shown to be efficient for pomegranate juice fermentation, as indicated by analysis of sugars and organic acids, and ethanol production was maintained at low levels (0.5–1% v/v). The sugars consumed during fermentation were used mainly for cell mass production, while DWB exerted a prebiotic effect, protecting and enhancing the viability of L. paracasei. Optimum viability (9.8–11.7 log cfu/mL) was achieved at pH 3.9. The phenolic content and headspace volatiles were increased after fermentation and storage (112 ± 17–213 ± 30 mg GAE/100 mL and 27–46 compounds, respectively), indicating potential to produce good quality, synbiotic pomegranate beverages.

In the frame of efforts to exploit agroindustrial side-streams and wastes (AISS) for added-value products that are based on single cell protein (SCP), mixed substrates consisting of brewer’s spent grains (BSG), malt spent rootlets (MSR), cheese whey, molasses, orange, and potato pulps, were used for growth of the edible mushroom Pleurotus ostreatus. The substrates were mixed in various combinations, and were used for P. ostreatus growth at various conditions. The substrate, for which the highest sugar consumption, protein increase, and mycelium yield were observed, consisted of 20 mL molasses (4° Baume density), 20 mL potato pulp, 5 mL whey, 5 mL orange pulp, 30 g BSG, and 5 g MSR (at 25 °C and substrate pH 4). The mycelium-enriched product was analyzed for protein, fat, minerals (Ca, Mg, Fe, Cu), and aroma volatile compounds, indicating the potential for use as nutritious supplement for food, feed, or microbiology uses. The product was also autolyzed, freeze-dried, powdered, and analyzed for total ribonucleic acid content, showing the potential for use as a commercial natural food flavor enhancer.

Amylases and proteases are among the most important industrial enzymes, being responsible for a global billionaire market. Although produced at industrial level mainly via submerged fermentation, historical series of scientific publications reveal that solid-state fermentation (SSF) is of major interest for research. This chapter presents insights about classification, market, and production of amylases and proteases via SSF processes using agro-industrial wastes/by-products. Moreover, their application in a biorefinery concept to obtain carbon and nitrogen-rich hydrolysates (namely nutrient medium) is discussed, with some examples of its use to obtain bioproducts of industrial interest, such as polyhydroxyalkanoates, microbial oil, 1,3-propanediol, and succinic acid.

Nowadays, an increasing worldwide interest in the use of renewable energy sources and the production of biofuels through the use of agro-industrial waste biomass as substrate for biofuels has become a necessity. Therefore several studies have reported the use of wastes for biofuel production including ethanol, methane and hydrogen. Another biorefinery concept for wastes exploitation includes its use as a substrate for anaerobic acidogenesis, to produce organic acids (OAs). Low molecular weight OAs have many applications, including biogas and biodiesel production, and their production through anaerobic fermentation of waste biomass has the advantage of being a cost-effective and environmentally friendly process. The produced OAs can be esterified with the produced ethanol or/and with an added alcohol, to esters that may be used as a new biofuel. The use of such esters in a homogeneous charge compression ignition engine, gave promising results for the use of such alternative liquid biofuel. This chapter presents different aspects of the production of an ester-based biofuel from wastes. Agro-industrial waste is being used as the raw material for organic acid production through microbial processes, which after passing through the esterification process, will lead to the production of a 2nd generation biofuel.

An industrial process for black table olives fermentation was followed in order to study the effect of immobilized halophile culture and the initial halophile culture concentration in combination with temperature for a period of 30 days. For comparison, three types of batch fermentation were investigated: (a) fermentation with the indigenous microbiota (control), (b) inoculated fermentation with isolated mixed halophile culture (MHC) and (c) inoculated fermentation with isolated MHC on tubular cellulose (TC). The effects of (i) temperature (5 and 20 °C) and (ii) initial biomass concentration (0.15, 0.5, 1 and 1.5 g/300 ml brine) on pH, brine and total volatiles were studied. Immobilized MHC cells on TC increased the fermentation rate as compared with free MHC cells. When immobilized MHC was used in fermentation, pH values remained close to 4.0 for all initial culture concentrations and lower than that for natural fermentation for 30 days at 5 °C. Especially for 1 g of biomass/300 ml of brine initial culture, the pH remained lower than 3.4 during the 30 days of fermentation at 5 °C. At the case of immobilized halophile cells at 5 °C, propionic acid was produced (max. 26.74 ± 1.21 g/L) which acted as natural preservative, while there was increase in total volatiles.

The aim of the present study was to evaluate the use of kefir culture entrapped in casein and in whey protein as starter cultures for the production of Feta-type cheese. Microbiological analysis showed that counts of enterobacteria, coliforms, and staphylococci were significantly reduced due to kefir culture. In addition, the effect of kefir culture on the formation of volatile compounds, such as esters, organic acids, alcohols, carbonyl compounds, and lactones, was also investigated using the SPME GC/MS technique. Cheese samples produced with kefir culture entrapped in milk proteins presented improved profile of aroma-related compounds. Principal component analysis of the results indicated that the volatile composition of the different cheese types was dependent on the nature of the starter culture. Finally, the sensory evaluation showed that the products produced with kefir culture had a soft, fine taste, and were of improved quality.

Resin from Pistacia terebinthus tree was used for the immobilization of L. casei ATCC 393 cells. The encapsulated L. casei cells biocatalysts were added as adjuncts during yogurt production at 45 °C and probiotic viability was assessed during storage at 4 °C. For comparison reasons yogurt with free L. casei cells were prepared. The effect of encapsulated bacteria as adjuncts in yogurt on pH, lactic acid, lactose and other physicochemical parameters were studied for 60 storage days at 4 °C. Samples were also tested for the microbiological and organoleptic characteristics during storage at 4 °C. Encapsulation matrix seems to sustain the viability of embedded L. casei cells at levels more than 7 logcfug(-1) after 60 days of storage at 4 °C. Furthermore, the absence of pathogens such as Salmonella, Staphylococci, Enterobacteriaceae and coliforms in the produced yogurts is noteworthy where spoilage microorganisms such as yeasts and molds seem to affect yogurt quality only in absence of Pistacia terebinthus resin. The effect of the resin on production of aroma-related compounds responsible for yogurt flavor was also studied using the solid phase microextraction gas chromatography/mass spectrometry technique. Alpha and beta- pinene were the major aroma compounds detected in produced yogurts (over 60 % of total aromatic compounds detected). Yogurts with immobilized cells on P.terebintus resin had a fine aroma and taste characteristic of the resin.