Microencapsulated enzyme systems for the acceleration of cheese ripening

Microbial lipases and their industrial applications: a comprehensive review

Lipases are very versatile enzymes, and produced the attention of the several industrial processes. Lipase can be achieved from several sources, animal, vegetable, and microbiological. The uses of microbial lipase market is estimated to be USD 425.0 Million in 2018 and it is projected to reach USD 590.2 Million by 2023, growing at a CAGR of 6.8% from 2018. Microbial lipases (EC 3.1.1.3) catalyze the hydrolysis of long chain triglycerides. The microbial origins of lipase enzymes are logically dynamic and proficient also have an extensive range of industrial uses with the manufacturing of altered molecules. The unique lipase (triacylglycerol acyl hydrolase) enzymes catalyzed the hydrolysis, esterification and alcoholysis reactions. Immobilization has made the use of microbial lipases accomplish its best performance and hence suitable for several reactions and need to enhance aroma to the immobilization processes. Immobilized enzymes depend on the immobilization technique and the carrier type. The choice of the carrier concerns usually the biocompatibility, chemical and thermal stability, and insolubility under reaction conditions, capability of easy rejuvenation and reusability, as well as cost proficiency. Bacillus spp., Achromobacter spp., Alcaligenes spp., Arthrobacter spp., Pseudomonos spp., of bacteria and Penicillium spp., Fusarium spp., Aspergillus spp., of fungi are screened large scale for lipase production. Lipases as multipurpose biological catalyst has given a favorable vision in meeting the needs for several industries such as biodiesel, foods and drinks, leather, textile, detergents, pharmaceuticals and medicals. This review represents a discussion on microbial sources of lipases, immobilization methods increased productivity at market profitability and reduce logistical liability on the environment and user.

Enzymes inside lipid vesicles: preparation, reactivity and applications

There are a number of methods that can be used for the preparation of enzyme-containing lipid vesicles (liposomes) which are lipid dispersions that contain water-soluble enzymes in the trapped aqueous space. This has been shown by many investigations carried out with a variety of enzymes. A review of these studies is given and some of the main results are summarized. With respect to the vesicle-forming amphiphiles used, most preparations are based on phosphatidylcholine, either the natural mixtures obtained from soybean or egg yolk, or chemically defined compounds, such as DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) or POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine). Charged enzyme-containing lipid vesicles are often prepared by adding a certain amount of a negatively charged amphiphile (typically dicetylphosphate) or a positively charged lipid (usually stearylamine). The presence of charges in the vesicle membrane may lead to an adsorption of the enzyme onto the interior or exterior site of the vesicle bilayers. If (i) the high enzyme encapsulation efficiencies; (ii) avoidance of the use of organic solvents during the entrapment procedure; (iii) relatively monodisperse spherical vesicles of about 100 nm diameter; and (iv) a high degree of unilamellarity are required, then the use of the so-called 'dehydration-rehydration method', followed by the 'extrusion technique' has shown to be superior over other procedures. In addition to many investigations in the field of cheese production--there are several studies on the (potential) medical and biomedical applications of enzyme-containing lipid vesicles (e.g. in the enzyme-replacement therapy or for immunoassays)--including a few in vivo studies. In many cases, the enzyme molecules are expected to be released from the vesicles at the target site, and the vesicles in these cases serve as the carrier system. For (potential) medical applications as enzyme carriers in the blood circulation, the preparation of sterically stabilized lipid vesicles has proven to be advantageous. Regarding the use of enzyme-containing vesicles as submicrometer-sized nanoreactors, substrates are added to the bulk phase. Upon permeation across the vesicle bilayer(s), the trapped enzymes inside the vesicles catalyze the conversion of the substrate molecules into products. Using physical (e.g. microwave irradiation) or chemical methods (e.g. addition of micelle-forming amphiphiles at sublytic concentration), the bilayer permeability can be controlled to a certain extent. A detailed molecular understanding of these (usually) submicrometer-sized bioreactor systems is still not there. There are only a few approaches towards a deeper understanding and modeling of the catalytic activity of the entrapped enzyme molecules upon externally added substrates. Using micrometer-sized vesicles (so-called 'giant vesicles') as simple models for the lipidic matrix of biological cells, enzyme molecules can be microinjected inside individual target vesicles, and the corresponding enzymatic reaction can be monitored by fluorescence microscopy using appropriate fluorogenic substrate molecules.

Neutrase entrapment in stable multilamellar and large unilamellar vesicles for the acceleration of cheese ripening

We report the encapsulation of neutrase in liposomes for the acceleration of cheese ripening. The liposome preparation procedure consisted of repeated freeze-thaw cycles of multilamellar vesicles followed by extrusion through polycarbonate filters. The neutrase encapsulation efficiency in the liposomes was influenced by the number of freeze-thaw cycles, achieving the highest value after seven cycles. Filtration through 200-nm polycarbonate membranes yielded homogenous size liposome populations with trapping efficiencies of about 65%. The vesicle stability and low neutrase release during the first stages of the cheese-making procedure, coupled with an almost quantitative retention of neutrase-loaded liposomes in cheese curd, ensured a proteolysis rate that was twice that observed in the control cheese.

Antilisterial activity of pediocin AcH in model food systems in the presence of an emulsifier or encapsulated within liposomes

The listericidal activity of pediocin AcH was evaluated in slurries (5, 10, or 25% in dH2O) of nonfat dry milk, butterfat, beef muscle tissue, or beef tallow. Slurries were inoculated with Listeria monocytogenes (2-strain mixture; 2.5 x 10(6) cfu/ml) and then with pediocin AcH (30,000 arbitrary units (AU) per ml of slurry). Although pediocin activity was reduced in slurries, sufficient pediocin remained to decrease the listeriae population. For all slurries tested, the greatest decrease in counts of Listeria (1.2-1.8 log10 cfu decrease) and decrease in pediocin activity (12-54% recovery of original activity) occurred within 1.5 min of addition of pediocin to slurries. Thereafter, counts of Listeria did not change appreciably, but pediocin activity continued to decrease in most treatments for up to 60 min. In general, greater activity was recovered from: (i) slurries of lower (5%) compared to higher (25%) concentrations of food; and (ii) dairy- compared to meat-based slurries. Next, pediocin AcH was encapsulated within phosphatidyl-choline-based liposomes before addition to slurries (10%), or was used unencapsulated in slurries (10%) containing the emulsifier Tween 80. Greater pediocin activity (29-62% increase; average over all concentrations) was recovered from slurries containing encapsulated compared to free pediocin AcH. Likewise, greater pediocin activity was recovered from slurries containing an emulsifier (4-90% increase; average over all concentrations) compared to otherwise similar slurries without Tween 80. The additional recovery of pediocin activity afforded by liposomes or Tween 80 underscores the potential for direct application of biopreservatives to provide another hurdle for L. monocytogenes in foods.

Encapsulation of food ingredients

Microencapsulation is a relatively new technology that is used for protection, stabilization, and slow release of food ingredients. The encapsulating or wall materials used generally consist of starch, starch derivatives, proteins, gums, lipids, or any combination of them. Methods of encapsulation of food ingredients include spray-drying, freeze-drying, fluidized bed-coating, extrusion, cocrystallization, molecular inclusion, and coacervation. This paper reviews techniques for preparation of microencapsulated food ingredients and choices of coating material. Characterization of microcapsules, mechanisms of controlled release, and efficiency of protection/stabilization of encapsulated food ingredients are also presented.

Recent advances in the large-scale production of lipid vesicles for use in food products: microfluidization

The development of a method for the continuous mass production of liposomes is vital for the industrial use of liposomes in food products. The method should be mild enough to prevent denaturation of the encapsulated material, and the materials used for the preparation of the liposomes should be safe and edible. Among the methods available, microfluidization seems to be the most promising. Microfluidization consists of processing emulsions under high pressure through an apparatus called a Microfluidizer. This apparatus also allows the production of another type of lipid vesicle: milkfat-coated microcapsules composed of milkfat and emulsifiers. The main advantages of microfluidization include the continuous production of large quantities of lipid vesicles without dissolving the phospholipids in organic solvents. These vesicles could be used in various food products for a variety of objectives. The addition of encapsulated material in liposomes or in milkfat-coated microcapsules to cheese milk resulted in a retention of 80-90% of the vesicles in the cheese, compared to only 2-4% if the material was added directly to the milk in the unencapsulated form. Liposomes and milkfat-coated microcapsules could be used as enzyme carriers to accelerate cheese ripening, or as carriers for flavouring systems to improve the organoleptic properties of low-fat cheeses or to impart distinctive flavours to new speciality cheeses. These microcapsules could also be used in food products to avoid undesirable side-reactions during food processing, or to supplement food products with nutritious additives.