Immobilization of biocatalysts for enzymatic polymerizations:Possibilities, advantages, applications

Biotechnology also holds tremendous opportunities for realizing functional polymeric materials. Biocatalytic pathways to polymeric materials are an emerging research area with not only enormous scientific and technological promise, but also a tremendous impact on environmental issues. Many of the enzymatic polymerizations reported proceed in organic solvents. However, enzymes mostly show none of their profound characteristics in organic solvents and can easily denature under industrial conditions. Therefore, natural enzymes seldom have the features adequate to be used as industrial catalysts in organic synthesis. The productivity of enzymatic processes is often low due to substrate and/or product inhibition. An important route to improving enzyme performance in non-natural environments is to immobilize them. In this review we will first summarize some of the most prominent examples of enzymatic polymerizations and will subsequently review the most important immobilization routes that are used for the immobilization of biocatalysts relevant to the field of enzymatic polymerizations. (C) 2011 Elsevier Ltd. All rights reserved

Effect of Convective Drying Method of Chokeberry (Aronia melanocarpa L.) on Drying Kinetics, Bioactive Components and Sensory Characteristics of Bread with Chokeberry Powder

The effects of three dehydration temperatures at 50, 60 and 70 °C of convective drying method on fresh fruits of black chokeberries (Aronia melanocarpa L.) were evaluated. The drying temperatures were found to have significantly different effects on the characteristics of dried fruits and powders, made by the dried fruits. The maximum drying rate at a temperature of 50 °C was 59 g/h, at 60 °C 102 g/h, and at 70 °C 115 g/h, and thus the drying time was 37 hours, 27 hours and 23 hours respectively. The drying temperature at 50 °C caused the least damage to the cell structure of the fresh chokeberries, bioactive components (anthocyanins, flavonoids, phenols) and total antioxidativity. The dehydrated chokeberries at the temperature of 50 °C had the highest ratio of total anthocyanins (376.89 ± 5.73 mg cyn-3-glu / 100 g dm), total flavonoids (1037.19 ± 3.83 mg CE / 100 g dm), phenols (1918.79 ± 3.26 mg GAE / 100 g dm) and antioxidant activity (37.11 ± 0.28 mg TE / 100 g dm). The drying process at a temperature of 50 °C required longer drying period, higher energy need and produced the chokeberry powder, which gave the bread with the best sensory characteristics, compared to a drying process at a temperature of 60 °C and 70 °C

Healthier Meat Products Are Fashionable—Consumers Love Fashion

Meat manufacturers are nowadays in a very unenviable position. Both meat and meat products require the utilization of various additives due to their chemical composition. On the other hand, consumers demand fresh, additive-free, and high-quality products with extended shelf-life, which might be considered as healthier, even functional food. These facts push manufacturers and researchers in pursuit of modern technologies and supplements to meet these high demands. Since a high daily intake of sodium and fat might cause severe health issues, reducing these ingredients in meat products is the first task towards healthier food. Sodium can be reduced by ultrasound, high-pressure processing, pulsed electric field, and replacement of NaCl with KCl, calcium gluconate, calcium glycerophosphate, calcium lactate, and monosodium glutamate. The reduction of the fat content can be achieved through a decrease in the amount of fatty tissue in the inital mixture and/or replacement with non-lipid components, or by partial fatty tissue replacement with oils rich in polyunsaturated fatty acids. Utilization of plant proteins (soy, wheat gluten, pea, chickpea, lentil, potato, barley, oat, rice, etc.), mycoproteins or micro-algae proteins, plant fats (palm and coconut fat, canola, sunflower, soy and corn oil, etc.), and polysaccharides (starches, fibers), accompanied by a meat-like fibrous structure, resulted in delicious “meat” products, which are considered a healthier alternative to real meat. Growing interest in the replacement of potentially adverse synthetic meat additives favors the use of plant (herb, fruit and vegetable) extracts, as an endless source of bioactive substances with strong antioxidant and antimicrobial activities. These extracts can be used either in raw meat or meat products, as well as in the fodder. Reformulation strategies strengthen and ensure the willingness of consumers to pay a higher price for their own demands regarding the naturalness of synthetic, clean-labeled, additive-free meat products. After a gradual alignment with strategic national/international recommendations and legal/sub-legal frameworks, the added value of such meat products opens wide the door to new segments/entire markets

Standardna lumbalna diskektomija nasuprot mikrodiskektomiji – razlike u ishodu liječenja i stopi reoperacije

Microdiscectomy (MD) is accepted nowadays as the operative method of choice for lumbar disc herniation, but it is not rare for neurosurgeons to opt for standard discectomy (SD), which does not entail the use of operating microscope. In our study, differences in disc herniation recurrence and clinical outcome of surgical treatment of lumbar disc herniation with and without the use of operating microscope were assessed. Our study included 167 patients undergoing lumbar disc surgery during a three-year period (SD, n=111 and MD, n=56). Clinical outcome assessments were recorded by patients via questionnaire forms filled out by patients at three time points. Operation duration, length of hospital stay and revision surgeries were also recorded. According to study results, after one-year follow up there was no statistically significant difference between the SD and MD groups in functional outcome. However, we recorded a statistically significant difference in leg pain reduction in favor of the MD group. According to the frequency of reoperations with the mean follow up period of 33.4 months, there was a statistically significant difference in favor of the MD group (SD 6.3% vs. MD 3.2%). There appears to be no particular advantage of either technique in terms of functional outcome since both result in good overall outcome. However, we choose MD over SD because it includes significantly lower recurrent disc herniation rate and higher reduction of leg pain.Mikrodiskektomija (MD) je danas prihvaćena kao operativna metoda izbora u liječenju lumbalne diskus hernije, ali se neurokirurzi nerijetko odlučuju za standardnu diskektomiju (SD) koja ne podrazumijeva upotrebu operativnog mikroskopa. U našoj studiji smo nastojali uočiti razlike vezano za rekurentnu diskus herniju i funkcionalni ishod kirurškog liječenja lumbalne diskus hernije uz uporabu operativnog mikroskopa i bez nje. Naša studija je uključila 167 bolesnika koji su podvrgnuti operaciji lumbalne diskus hernije tijekom trogodišnjeg razdoblja (SD, n=111 i MD, n=56). Ishod liječenja procjenjivao se pomoću upitnika koji su bolesnici ispunjavali u tri vremenske točke. Vrijeme trajanja operacije, dužina hospitalizacije i reoperacije su također bilježeni. Nakon godinu dana praćenja prema našim rezultatima nije bilo statistički značajne razlike između skupina SD i MD u funkcionalnom ishodu liječenja, ali je zabilježena statistički značajna razlika u smanjenju boli u nozi u korist skupine MD. Prema učestalosti reoperacija s prosječnim razdobljem praćenja od 33,4 mjeseca, utvrđena je statistički značajna razlika u korist skupine MD (SD, 6,3% i MD, 3,2%). Nijednoj operativnoj tehnici ne može se dati prednost u smislu funkcionalnog ishoda liječenja, jer obje daju odlične rezultate. Ipak, naš izbor je mikrodiskektomija zbog niže stope rekurentne diskus hernije i višeg stupnja smanjenja boli u nozi

Kvalitet šljivovica od sorata šljive kombinovanih svojstava

Besides plum cultivars intended for brandy making, numerous plum cultivars with combined traits are also used for the production of plum brandy in Serbia. The latter are used as dessert fruits, as well as for freezing and processing into prunes, jam, marmalade, compote, etc. In some years, depending on market trends, larger or smaller quantities of high-quality fruits of the these cultivars, which are, otherwise, intended for both fresh consumption and processing by means of different methods of preservation, are being processed into brandy. In seasons in question, plum fruits are harvested exactly at the moment when they reach the stage of maturity that is common for plums intended for processing into brandy. In this paper we investigated physical and chemical properties of fruits of five cultivars with combined traits widely grown in Serbia - 'Čačanska Lepotica', 'Čačanska Najbolja', 'Čačanska Rodna', 'Valjevka' and 'Stanley', grown on two localities. Processing of the tested plum varieties into brandy was done in the same manner. Physical and chemical analysis was performed as well as the assessment of sensory characteristics of the produced plum brandies. Fruit characteristics of individual varieties, as well as the location from which these plum fruits originate are of great importance for the quality of brandy. The composition of produced plum brandies meets the legislation requirements of both Serbia and the EU. The utilization of high-quality fruits and applied technological processes resulted in considerably low content of undesirable components in plum brandies (methanol and prussic acid) which are below the legally permitted maximum. Differences in sensory assessment of brandies produced from the same cultivar, which depend on growing locality, ranged from 0.21 points (in 'Čačanska Najbolja') to 0.70 points (in 'Čačanska Rodna').U radu su ispitivane fizičko hemijske karakteristike plodova pet sorata šljive kombinovanih svojstava koje su široko zastupljene u voćarstvu Srbije - 'Čačanska lepotica', 'Čačanska najbolja', 'Čačanska rodna', 'Valjevka' i 'Stanley', sa dva lokaliteta. Šljive su obrane u stadijumu pune zrelosti i prerađene u šljivovicu na isti način. Izvršena je fizičko hemijska analiza i senzorna ocena proizvedenih sortnih šljivovica. Razlike u hemijskom sastavu i senzornim karakteristikama dobijenih šljivovica uslovljene su sortnim karakteristikama ploda i lokalitetom sa kojeg potiču. Sve šljivovice su zadovoljavale zahteve zakonske regulative Srbije i EU

Influence of Different Pre-Distillation Steps on Aromatic Profile of Plum Spirits Produced by Traditional and Modified Methods

The aim of this study was to compare the aromatic profile of plum spirits, obtained from the Požegača and Stanley varieties, as affected by different combinations of pre-distillation steps used in traditional and six modified production methods that are common in Serbian distilleries. Traditional plum spirits (produced from spontaneously fermented mashes of crushed plums with stones distilled after two months of storage) had the highest contents of ethyl acetate, benzaldehyde, and total acids, which resulted in the occurrence of an unpleasant solvent-like and stone-like odour and acidic taste. These sensory defects were overcome by the distillation of fermented mashes immediately after the completion of alcoholic fermentation. Depending on the combination of the pre-distillation steps, plum spirits from mashes distilled immediately after alcoholic fermentation were characterized by different aromatic profiles: closer to traditional (from spontaneously fermented crushed plums with/without stones) or with a more pronounced fruity character (from pulped plums without stones regardless of the way of fermentation). These differences in aroma profiles have arisen mostly because of the significantly different contents and OAVs of ethyl esters and volatile fatty acids. The appropriate combination of the pre-distillation steps, which is adapted to the variety, can significantly improve the quality of the plum spirit compared to the traditionally produced spirit. © 2023 by the authors

Acetic acid bacteria-derived bacterial nanocellulose: sustainable synthesis and antimicrobial potential development

Acetic acid bacteria (AAB) are renowned for their proficiency in bacterial cellulose (BC) production, particularly species within the Acetobacter and Komagataeibacter genera. BC, derived solely from bacterial cells, represents the purest form of cellulose known, with AAB capable of generating quantities viable for commercial utilization. The utilization of bacteria for biopolymer or cellulose hydrogel production, as opposed to traditional plant sources requiring aggressive chemical treatments, presents a sustainable approach with environmental preservation benefits.While BC materials inherently lack functional properties, their porous structure and three-dimensional nanofiber network with high specific surface area render them ideal carriers for antimicrobials or other agents in the production of functional composite materials. Moreover, by-products or wastes that contain carbon or nitrogen sources for AAB could potentially substitute some part of conventional substrates, reducing production costs of BC and conserving resources.This study involved the identification of eight isolates from two kombucha beverages using molecular method, followed by screening for the most proficient cellulose-producing species. Morphological characterization of cellulose was conducted using scanning electron microscopy (SEM), while X-ray diffraction (XRD) was employed for crystallinity and phase analysis. Functionalization of nanocellulose involved the incorporation of titanium dioxide and hydroxyapatite, with elemental composition analyzed using energy-dispersive X-ray (EDS) techniques. Antimicrobial properties were evaluated using plate count tests. Additionally, discarded ethanol waste from the functionalization step was investigated for sustainable BC cellulose production.Isolated species demonstrated the production of pure, nanosized, densely intertwined BC polymers with high crystallinity. EDS analysis confirmed the presence of only carbon and oxygen elements in pure cellulose. While pure BC exhibited no antimicrobial activity, functionalized BC demonstrated antifungal and antibacterial properties. Furthermore, discarded ethanol waste proved effective for BC synthesis. These findings underscore the potential applications of functionalized BC in touch surfaces, coatings, packaging, agriculture, and medicine

Effects of Synthesis Parameters on Structure and Antimicrobial Properties of Bacterial Cellulose/Hydroxyapatite/TiO2 Polymer–Ceramic Composite Material

Bacterial cellulose (BC) is a highly pure polysaccharide biopolymer that can be produced by various bacterial genera. Even though BC lacks functional properties, its porosity, three-dimensional network, and high specific surface area make it a suitable carrier for functional composite materials. In the present study, BC-producing bacteria were isolated from kombucha beverage and identified using a molecular method. Two sets of the BC hydrogels were produced in static conditions after four and seven days. Afterwards, two different synthesis pathways were applied for BC functionalization. The first method implied the incorporation of previously synthesized HAp/TiO2 nanocomposite using an immersion technique, while the second method included the functionalization of BC during the synthesis of HAp/TiO2 nanocomposite in the reaction mixture. The primary goal was to find the best method to obtain the functionalized material. Physicochemical and microstructural properties were analyzed by SEM, EDS, FTIR, and XRD methods. Further properties were examined by tensile test and thermogravimetric analysis, and antimicrobial activity was assessed by a total plate count assay. The results showed that HAp/TiO2 was successfully incorporated into the produced BC hydrogels using both methods. The applied methods of incorporation influenced the differences in morphology, phase distribution, mechanical and thermal properties, and antimicrobial activity against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Proteus mirabilis (ATCC 12453), and Candida albicans (ATCC 10231). Composite material can be recommended for further development and application in environments that are suitable for diseases spreading

Antioxidant potential of herbs and spices in nitrite-reduced frankfurter sausages

Nitrites are used in meat processing as a preservative, but there is a need to reduce their usage because of their potential harmful effects on consumers’ health. The antioxidant potential of different herbs and spices in nitrite-reduced frankfurter type sausages and their influence on the products’ sensory properties were investigated. The results show the nitrite-reduced sausages enriched with individual herbs or spices as a source of phenolic compounds had significant antioxidant potential, which was the highest in sausages with rosemary followed by sausages with thyme, black pepper, turmeric, and red paprika. Spice-enriched sausages had better sensory properties then the control sausages after chill storage

Techno-Functional Properties of Burgers Fortified by Wild Garlic Extract: A Reconsideration

The aim of this research was to examine the chemical properties of freshly squeezed wild garlic extract (FSWGE) and its use as an additive in burgers (BU). Technological and sensory properties of such fortified burgers (BU) were determined. LC-MS/MS analyses identified thirty-eight volatile BAC. Allicin prevalence (11.375 mg/mL) is the key parameter determining the amount of FSWGE added in raw BU (PS-I 1.32 mL/kg, PS-II 4.40 mL/kg, and PS-III 8.79 mL/kg). Minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) values of the FSWGE and evaporated FSWGE (EWGE) were determined against the six microorganisms using a microdilution method. The data indicated that using FSWGE can result in a reduced risk of Serratia marcescens (MIC = 50 mg/mL; MBC = 60 mg/mL), Listeria monocytogenes (MIC = MBC = 90 mg/mL), Escherichia coli and Staphylococcus aureus (MIC = 90 mg/mL; MBC ≥ 100 mg/mL), and Salmonella enteritidis and Enterococcus faecium (MIC = 100 mg/mL; MBC > 100 mg/mL) in BU. Changes in antioxidant (AOX) capacity were followed during cold storage (up to 10 days) and freezing (90 days). It was shown that PS-III had the highest level of AOX capacity during the entire period of cold storage, revealing 8.79 mL FSWGE/kg BU as the most suitable effective concentration. Adding FSWGE did not negatively affect the technological and physico-chemical properties during both cold and freeze storage. Regarding sensory evaluation, modified BU received mostly higher scores compared to control. The results of this study have demonstrated the great potential of wild garlic extract usage in the creation of safe products with prolonged shelf life. © 2023 by the authors