Encapsulation of ligninolytic enzymes and its application in clarification of juice

Application of Immobilized Enzymes in Juice Clarification

Immobilized enzymes are currently being rapidly developed and are widely used in juice clarification. Immobilized enzymes have many advantages, and they show great advantages in juice clarification. The commonly used methods for immobilizing enzymes include adsorption, entrapment, covalent bonding, and cross-linking. Different immobilization methods are adopted for different enzymes to accommodate their different characteristics. This article systematically reviews the methods of enzyme immobilization and the use of immobilized supports in juice clarification. In addition, the mechanisms and effects of clarification with immobilized pectinase, immobilized laccase, and immobilized xylanase in fruit juice are elaborated upon. Furthermore, suggestions and prospects are provided for future studies in this area.

Application of natural fining agents to clarify fruit juices

The consumption of fruit juices has been increasingly growing all over the world. The clarification process is considered as one of the most important stages in fruit juice production, which can provide the products with desired clear visual appearance. Nowadays, the tendency of consumers to use the natural-clarified fruit juices encourages the researchers to allocate much attention on utilization of natural clarifying agents to clarify different fruit juices. This review article has first introduced the most frequent causes of turbidity in fruit juices including polysaccharides (i.e., cellulose, hemicelluloses, lignin, starch, and pectic substances), proteins and polyphenols (especially tannins) as well as their removal mechanisms. After that, a comprehensive summary of research on natural fining agents, including clay minerals, polysaccharides, proteins, enzymes (free and immobilized forms), and activated carbon is provided with a focus on their application in the juice clarification process. The chemical composition of natural substances, their efficiency on reduction of turbidity-causing compounds and the changes in properties of clarified juices such as turbidity (clarity), total phenolic content, total anthocyanins, viscosity, and sensory evaluation followed by their stability during the storage have been deeply discussed.

Improving the thermal stability of natural bioactive ingredients via encapsulation technology

Bioactive compounds (bioactives) such as phenolic acids, coumarins, flavonoids, lignans and carotenoids have a marked improvement effect on human health by acting on body tissues or cells. Nowadays, with increasing levels of knowledge, consumers prefer foods that can provide bioactives beside the necessary nutrients (e.g., vitamins, essential fatty acids and minerals). However, an important barrier for incorporating bioactives into foods is their low thermal stability. Nevertheless, thermal processing is widely used by the food industries to achieve food safety and desired texture. The aim of this work is to give an overview of encapsulation technology to improve thermal stability of bioactives incorporated into different food products. Almost all thermal analysis and non-thermal methods in the literature suggest that incorporation of bioactives into different walls can effectively improve the thermal stability of bioactives. The level of such thermal enhancement depends on the strength of the bioactive interaction and wall molecules. Furthermore, contradictory results have been reported in relation to the effect of encapsulation technique using the same wall on thermal stability of bioactives. To date, the potential to increase the thermal resistance of various bioactives by gums, carbohydrates, and proteins have been extensively studied. However, further studies on the comparison of walls and encapsulation methods to form thermally stable carriers seem to be needed. In this regard, the same nature of bioactives and the specific protocol in the report of study results should be considered to compare the data and select the optimum conditions of encapsulation to achieve maximum thermal stability.

Microencapsulation in food industry – an overview

In the modern health concept, food quality is becoming more and more important. People are increasingly looking for added value to their diet through the presence of bioactive substances. Usually, the latter are sensitive molecules; they are unstable in processing and consumption. In addition, problems with unpleasant organoleptic characteristics clean labelling and high production costs can occur. To overcome these problems, a solution can be sought in microencapsulation techniques. Although these techniques have been known for a long time, nowadays their meaning and significance are gaining new dimensions. In this regard, this review aims to provide up-to-date information on currently used microencapsulation techniques, limitations, and prospects.

Protection and Controlled Gastrointestinal Release of Bromelain by Encapsulating in Pectin-Resistant Starch Based Hydrogel Beads

Hybrid pectin and resistant starch–based hydrogel beads loaded with bromelain using the extrusion gelation method were prepared and evaluated to enhance the activity of bromelain during gastrointestinal passage and thermal processing. The solutions of pectin–resistant starch with bromelain were dropped into the gelation bath containing calcium chloride (0.2 M) solution to develop various types of hydrogel beads. The physicochemical characteristics of the synthesized hydrogel beads were evaluated. The ratio (4.5:1.5 w/w) of pectin and resistant starch concentration significantly (p < 0.05) enhanced the encapsulation efficiency (80.53%). The presence of resistant starch resulted in increased entrapment of bromelain, improved swelling properties with sustained release behavior, and improved gastric stability than pectin hydrogels alone. The swelling of hydrogel beads was higher at pH 7.4 than pH 1.2. Optimized batch of hybrid pectin/resistant starch exhibited a spherical shape. Optical and scanning electron microscopy showed a more packed and spherical shape from the pectin/resistant starch hydrogel bead network. Fourier transformation infrared spectroscopy was also used to confirm the presence of bromelain in the hydrogel beads. The encapsulated bromelain in the pectin/hi-maize starch beads produced at a pectin/hi-maize ratio of 4.5:1.5 (percent w/w; formulation P4) obtained the highest relative bromelain activity in all heat treatments including at 95°C, whereas the highest activity of free bromelain was found only at 30°C. Bromelain encapsulated in hydrogels released at a faster rate at simulated intestinal fluid (SIF, pH 7.4) than at simulated gastrointestinal fluid (SGF, pH 1.2).

One pot clarification and debittering of grapefruit juice using co-immobilized enzymes@chitosanMNPs

In the present work, enzymes pectinase and naringinase were simultaneously co-immobilized on an eco-friendly chitosan coated magnetic nanoparticles (chitosanMNPs) by cross-linking using chitosan as a macro-molecular cross-linker. The maximum activity recovery of both enzymes in the co-immobilized form was obtained at chitosanMNPs to enzymes ratio of 1:3, 3% cross-linker concentration and 150 min cross-linking time. The synthesized MNPs before and after co-immobilization were characterized using different techniques. The prepared biocatalyst was found spherical with an average size below 200 nm and showed supermagnetic property with saturation magnetization of 38.28 emu/g. The optimum pH and temperature of both enzymes in co-immobilized form was found at 5.5 and 65 °C. The prepared biocatalyst exhibited an improved thermal stability with 1.8-fold increase in the half-life. The secondary structural analysis revealed that, prepared co-immobilized biocatalyst undergone changes in the conformational and structural rigidity due to macro-molecular cross-linker. The co-immobilized biocatalysts were evaluated for one pot clarification and debittering of grapefruit juice and found ~52% reduction in turbidity and ~85% reduction in the naringin content. The co-immobilized enzymes were recycled up to 7^th cycle and can be easily stored at room temperature for 30 days retaining up to 64% and 86% residual activities respectively.

Multi-Functional Laccase Immobilized Hydrogel Microparticles for Efficient Removal of Bisphenol A

Hghly stable, reusable, and multi-functional biocatalytic microparticles with Laccase (Lac) enzyme (Lac/particles) were synthesized for bisphenol A (BPA) removal from aqueous solution. The Lac/particles were prepared by encapsulating Lac enzymes into poly ethylene glycol (PEG) hydrogel via the UV assisted emulsion polymerization method followed by cross linking with glutaraldehyde (GA). The obtained Lac/particles were spherical and micron sized (137⁻535 μm), presenting high enzyme entrapment efficiency of 100%, high activity recovery of 18.9%, and great stability at various pHs (3⁻7) than the free Lac. The Lac/particles could adsorb the BPA into the catalytic particles in a short time, promoting contact between BPA and enzyme, and further enzymatically degrade them without the shaking process and independent surrounding buffer solution. The Lac/particles could be reused for another round BPA adsorption and biotranformation by maintaining over 90% of BPA removal efficiency after seven times reuse. The synergistic effects of adsorption and biocatalytical reaction of Lac/particles have significant values in high efficient and cost-effective BPA removal.

"Smart" chemistry and its application in peroxidase immobilization using different support materials

In the past few decades, the enzyme immobilization technology has been exploited a lot and thus became a matter of rational design. Immobilization is an alternative approach to bio-catalysis with the added benefits, adaptability to automation and high-throughput applications. Immobilization-based approaches represent simple but effective routes for engineering enzyme catalysts with higher activities than wild-type or pristine counterparts. From the chemistry viewpoint, the concept of stabilization via manipulation of functional entities, the enzyme surfaces have been an important driving force for immobilizing purposes. In addition, the unique physiochemical and structural functionalities of pristine or engineered cues, or insoluble support matrices (carrier) such as mean particle diameter, swelling behavior, mechanical strength, and compression behavior are of supreme interest and importance for the performance of the immobilized systems. Immobilization of peroxidases into/onto insoluble support matrices is advantageous for practical applications due to convenience in handling, ease separation of enzymes from a reaction mixture and the reusability. A plethora of literature is available explaining individual immobilization system. However, current literature lacks the chemistry viewpoint of immobilization. This review work presents state-of-the-art "Smart" chemistry of immobilization and novel potentialities of several materials-based cues with different geometries including microspheres, hydrogels and polymeric membranes, nanoparticles, nanofibers, composite and hybrid or blended support materials. The involvement of various functional groups including amino, thiol, carboxylic, hydroxyl, and epoxy groups via "click" chemistry, amine chemistry, thiol chemistry, carboxyl chemistry, and epoxy chemistry over the protein surfaces is discussed.

Laccase From White Rot Fungi Having Significant Role in Food, Pharma, and Other Industries

Laccases (E.C. 1.10.3.2 benzenediol: oxygen oxidoreductase) are an interesting group of N glycosylated multicopper blue oxidase enzymes and the widely studied enzyme having a broad range of substrate specificity of both phenolic and non-phenolic compounds. They are widely found in fungi, bacteria plant, insects, and in lichen. They catalyze the oxidation of various phenolic and non-phenolic compounds, with the concomitant reduction of molecular oxygen to water. They could increase productivity, efficiency, and quality of products without a costly investment. This chapter depicts the applications of laccase enzyme from white rot fungi, having various industrial (such as textile dye bleaching, paper and pulp bleaching, food includes the baking, it also utilized in fruit juice industry to improve the quality and stabilization of some perishable products having plant oils), pharmaceutical (as it has potential for the synthesis of several useful drugs such anticancerous, antioxidants, synthesis of hormone derivatives because of their high value of oxidation potential) significance.

Biotransformation of lignocellulosic materials into value-added products-A review

In the past decade, with the key biotechnological advancements, lignocellulosic materials have gained a particular importance. In serious consideration of global economic, environmental and energy issues, research scientists have been re-directing their interests in (re)-valorizing naturally occurring lignocellulosic-based materials. In this context, lignin-modifying enzymes (LMEs) have gained considerable attention in numerous industrial and biotechnological processes. However, their lower catalytic efficiencies and operational stabilities limit their practical and multipurpose applications in various sectors. Therefore, to expand the range of natural industrial biocatalysts e.g. LMEs, significant progress related to the enzyme biotechnology has appeared. Owing to the abundant lignocellulose availability along with LMEs in combination with the scientific advances in the biotechnological era, solid-phase biocatalysts can be economically tailored on a large scale. This review article outlines first briefly on the lignocellulose materials as a potential source for biotransformation into value-added products including composites, fine chemicals, nutraceutical, delignification, and enzymes. Comprehensive information is also given on the purification and characterization of LMEs to present their potential for the industrial and biotechnological sector.

Mycotoxin Biotransformation by Native and Commercial Enzymes: Present and Future Perspectives

Worldwide mycotoxins contamination has a significant impact on animal and human health, and leads to economic losses accounted for billions of dollars annually. Since the application of pre- and post- harvest strategies, including chemical or physical removal, are not sufficiently effective, biological transformation is considered the most promising yet challenging approach to reduce mycotoxins accumulation. Although several microorganisms were reported to degrade mycotoxins, only a few enzymes have been identified, purified and characterized for this activity. This review focuses on the biotransformation of mycotoxins performed with purified enzymes isolated from bacteria, fungi and plants, whose activity was validated in in vitro and in vivo assays, including patented ones and commercial preparations. Furthermore, we will present some applications for detoxifying enzymes in food, feed, biogas and biofuel industries, describing their limitation and potentialities.

Induction, purification, and characterization of a thermo and pH stable laccase from Abortiporus biennis J2 and its application on the clarification of litchi juice

A fungus J2 producing laccase with high yield was screened in soils and identified as Abortiporus biennis. The production of laccase was induced by 0.1 mM Cu²⁺, 0.1 mM tannic acid, and 0.5 M ethanol. The laccase from Abortiporus biennis J2 was purified to electrophoretic homogeneity by a couple of steps. The N-terminal amino acid sequence of the enzyme was AIGPTADLNISNADI. The properties of the purified laccase were investigated. The result showed the laccase from Abortiporus biennis J2 is a thermo and pH stable enzyme. The laccase activity was inhibited by Hg²⁺, Cd²⁺, Fe²⁺, Ag⁺, Cu²⁺, and Zn²⁺, while promoted by Mg²⁺, Mn²⁺ at 10 mM level. Purified laccase was used to the clarification of litchi juice. After treatment with this laccase, the phenolic content of litchi juice had been found to be greatly reduced along with an increase in the clarity of the juice. The result indicated the potential of this laccase for application in juice procession.

Improved Enzyme Catalytic Characteristics upon Glutaraldehyde Cross-Linking of Alginate Entrapped Xylanase Isolated from Aspergillus flavus MTCC 9390

Purified fungal xylanase was entrapped in alginate beads. Its further cross-linking using glutaraldehyde resulted in large enzyme aggregates which may function as both a catalyst and a support material for numerous substrate molecules. Enzyme cross-linking presented a negative impact on enzyme leaching during repeated washings and recovery of enzyme activity was substantial after twelve cycles of usage. The entrapment followed by cross-linking doubled the total bound activity and also greatly improved the enzyme stability at extreme chemical environment. The wide pH stability, better thermo- and storage stability, lowered K_m value, and protection from some metal ions are salient achievements of present immobilization. The study shows the efficacy, durability, and sustainability of immobilized catalytic system which could be efficiently used for various juice processing operations.

How to enjoy laccases

An analysis of the scientific literature published in the last 10 years reveals a constant growth of laccase applicative research in several industrial fields followed by the publication of a great number of patents. The Green Chemistry journal devoted the cover of its September 2014 issue to a laccase as greener alternative for chemical oxidation. This indicates that laccase "never-ending story" has found a new promising trend within the constant search for efficient (bio)catalysts able to meet the 12 green chemistry principles. A survey of ancient and cutting-edge uses of laccase in different industrial sectors is offered in this review with the aim both to underline their potential and to provide inspiration for new ones. Applications in textile and food fields have been deeply described, as well as examples concerning polymer synthesis and laccase-catalysed grafting. Recent applications in pharmaceutical and cosmetic industry have also been reviewed.

Microencapsulation of purified amylase enzyme from pitaya (Hylocereus polyrhizus) peel in Arabic gum-chitosan using freeze drying

Amylase is one of the most important enzymes in the world due to its wide application in various industries and biotechnological processes. In this study, amylase enzyme from Hylocereus polyrhizus was encapsulated for the first time in an Arabic gum-chitosan matrix using freeze drying. The encapsulated amylase retained complete biocatalytic activity and exhibited a shift in the optimum temperature and considerable increase in the pH and temperature stabilities compared to the free enzyme. Encapsulation of the enzyme protected the activity in the presence of ionic and non-ionic surfactants and oxidizing agents (H₂O₂) and enhanced the shelf life. The storage stability of amylase is found to markedly increase after immobilization and the freeze dried amylase exhibited maximum encapsulation efficiency value (96.2%) after the encapsulation process. Therefore, the present study demonstrated that the encapsulation of the enzyme in a coating agent using freeze drying is an efficient method to keep the enzyme active and stable until required in industry.