Toward Sourdough Microbiome Data: A Review of Science and Patents.

Technological prospecting was performed on documents related to sourdough microbiota using SCOPUS, Web of Science, Google Scholar, Espacenet and Patent Inspiration databases. Scientific articles and patents were analyzed based on three different perspectives: macro (year of publication, country, and institutions), meso (categorization as different taxonomies according to the subject evaluated), and micro (in-depth analysis of the main taxonomies, gathering the documents in subcategories). The main subject addressed in patents was the starter and product preparation, while 58.8% of the scientific publications focused on sourdough starter microbiota (identification and selection of microorganisms). Most patents were granted to companies (45.9%), followed by independent inventors (26.4%) and universities (21.8%). Sourdough products are in the spotlight when the subject is the bakery market; however, a closer integration between academia and industry is needed. Such a collaboration could generate a positive impact on the sourdough market in terms of innovation, providing a bread with a better nutritional and sensory quality for all consumers. Moreover, sourdough creates a new magnitude of flavor and texture in gastronomy, providing new functional products or increasing the quality of traditional ones.

Polymers as Encapsulating Agents and Delivery Vehicles of Enzymes.

Enzymes are versatile biomolecules with broad applications. Since they are biological molecules, they can be easily destabilized when placed in adverse environmental conditions, such as variations in temperature, pH, or ionic strength. In this sense, the use of protective structures, as polymeric capsules, has been an excellent approach to maintain the catalytic stability of enzymes during their application. Thus, in this review, we report the use of polymeric materials as enzyme encapsulation agents, recent technological developments related to this subject, and characterization methodologies and possible applications of the formed bioactive structures. Our search detected that the most explored methods for enzyme encapsulation are ionotropic gelation, spray drying, freeze-drying, nanoprecipitation, and electrospinning. α-chymotrypsin, lysozyme, and ß-galactosidase were the most used enzymes in encapsulations, with chitosan and sodium alginate being the main polymers. Furthermore, most studies reported high encapsulation efficiency, enzyme activity maintenance, and stability improvement at pH, temperature, and storage. Therefore, the information presented here shows a direction for the development of encapsulation systems capable of stabilizing different enzymes and obtaining better performance during application.

Palm oil wastes as feedstock for lipase production by Yarrowia lipolytica and biocatalyst application/reuse.

Palm oil production chain generates a greasy residue in the refining stage, the Palm Oil Deodorizer Distillate (PODD), mainly composed of free fatty acids. Palm oil is also used industrially to fry foods, generating a residual frying oil (RFO). In this paper, we aimed to produce lipase from palm agro-industrial wastes using an unconventional yeast. RFO_palm, from a known source, consisted of 0.11% MAG + FFA, 1.5% DAG, and 97.5 TAG, while RFO_commercial, from a commercial restaurant, contained 6.7% of DAG and 93.3% of TAG. All palm oil wastes were useful for extracellular lipase production, especially RFO_commercial that provided the highest activity (4.9 U/mL) and productivity (465 U/L.h) in 75 h of processing time. In 48 h of process, PODD presented 2.3 U/mL of lipase activity and 48.5 U/L.h of productivity. RFO_commercial also showed the highest values for lipase associated to cell debris (843 U/g). This naturally immobilized biocatalyst was tested on hydrolysis reactions to produce Lipolyzed Milk Fat and was quite efficient, with a hydrolysis yield of 13.1% and 3-cycle reuse. Therefore, oily palm residues seem a promising alternative to produce lipases by the non-pathogenic yeast Y. lipolytica and show great potential for industrial applications.

Waste soybean frying oil for the production, extraction, and characterization of cell-wall-associated lipases from Yarrowia lipolytica.

The lipolytic yeast Yarrowia lipolytica produces cell-wall-associated lipases, namely Lip7p and Lip8p, that could have interesting properties as catalyst either in free (released lipase fraction-RLF) or cell-associated (cell-bound lipase fraction-CBLF) forms. Herein, a mixture of waste soybean frying oil, yeast extract and bactopeptone was found to favor the enzyme production. Best parameters for lipase activation and release from the cell wall by means of acoustic wave treatment were defined as: 26 W/cm2 for 1 min for CBLF and 52 W/cm2 for 2 min for RLF. Optimal pH and temperature values for lipase activity together with storage conditions were similar for both the free enzyme and cell-associated one: pH 7.0; T = 37 °C; and > 70% residual activity for 60 days at 4, - 4 °C and for 15 days at 30 °C.

Efficient production of bioactive structured lipids by fast acidolysis catalyzed by Yarrowia lipolytica lipase, free and immobilized in chitosan-alginate beads, in solvent-free medium.

Structured lipids (SL) represent a new generation of lipids, considered bioactive compounds. Medium-chain, oleic (18:1n-9), and medium-chain fatty acid (MCFA) structured lipids (MOM-SL) were produced by acidolysis reaction in solvent-free medium with capric (10:0) and lauric (12:0) free fatty acids (FFAs) and triolein or olive oil, using Yarrowia lipolytica lipase as biocatalyst. MCFAs were rapidly incorporated into sn-1,3 SL in acidolysis reactions with triolein and olive oil, up until 30% of incorporation efficiency of capric and lauric acids in SLs. The kinetics of MCFA incorporation in MOM-SL was influenced by the FFA:TAG molar ratio, and for reactions between triolein and lauric acid, increasing FFA:TAG from 2:1 to 4:1 enhanced MCFA incorporation in SL. Y. lipolytica lipase showed a strictly 1,3-regioselective profile in acidolysis reaction, confirmed by nuclear magnetic resonance spectroscopy. Immobilization of this lipase by microencapsulation in chitosan-alginate beads resulted in similar incorporation efficiency for lauric acid with olive oil TAG and this reaction could be performed for 5 cycles without catalytic activity loss. This lipase showed promising properties as a potential biocatalyst that may be effectively used in production of bioactive structured lipids, which might be applied for prevention of metabolic and inflammatory disorders related to obesity.

Simple physical adsorption technique to immobilize Yarrowia lipolytica lipase purified by different methods on magnetic nanoparticles: Adsorption isotherms and thermodynamic approach.

Magnetic nanoparticles (Fe3O4) were used for physical adsorption of lipase from Yarrowia lipolytica IMUFRJ 50682. The optimal adsorption conditions were obtained as follows: enzyme/support 19.3 mg/g and temperature of 20 °C for standard protein. High immobilization efficiency of 99% was obtained for 4 mL of crude lipase extract (containing 0.315 mg protein/mL) and 0.02 g of magnetic nanoparticles and this biocatalyst was recycled 30 times with 70% of lipase activity in the end. Purified lipase extracts were also efficiently immobilized and ultrafiltered lipase extract (ULE) and aqueous two-phase system lipase extract (ATPS_LE) when immobilized revealed higher hydrolytic activity in relation to CLE (2.8 and 4.0 times higher, respectively). Broad pH tolerance and high thermostability could be achieved by immobilization on magnetic nanoparticles, with 40% improvement in thermodynamic parameters at 60 °C. Kinetic parameters Vmax and Km were also better for ULE (Vmax: 2.3 times higher; Km 43% reduction) and ATPS_LE (Vmax: 3.0 times higher; Km: 38% reduction) immobilized on magnetic nanoparticles in relation to CLE. These results showed that the immobilization of lipase onto magnetic nanoparticles by physical adsorption is an efficient and simple way to obtain a great catalyst.

Chitosan-alginate beads as encapsulating agents for Yarrowia lipolytica lipase: Morphological, physico-chemical and kinetic characteristics.

Extracellular lipase from Yarrowia lipolytica was immobilized by ionotropic gelation with alginate and chitosan as encapsulating agents. Photomicrographs revealed a collapsed and heterogeneous surface of these microcapsules due to freeze-drying process. The optimum reaction temperature for the microencapsulated lipase (40 °C) was higher than for free lipase (35 °C) as well as the optimum pH (8.0 and 7.5, respectively). The study of the reaction kinetics showed that a higher maximum reaction rate (Vmax) (221.1 U/mg) for the free lipase in comparison to the immobilized form (175.3 U/mg). A protective effect of the microcapsule was detected in the storage of the enzyme at room temperature, as after 75 days 35% of activity was maintained for the microcapsules, while no activity remained after 15 days with the free enzyme. Lower values for inactivation constant (kd) and increase in half-life for immobilized lipase showed that lipase microencapsulation favored the thermostability of this enzyme.

Microencapsulation of tiger nut milk by lyophilization: Morphological characteristics, shelf life and microbiological stability.

Tiger nut milk is a nutrient rich drink with great commercialization potential. However, it is highly perishable. Microencapsulation of tiger nut milk by a blend of inulin and modified tiger nut starch resulted in a product with good characteristics. The microspheres of lyophilized tiger nut milk were spherical with and average particle size of 1.01 µm. It's thermal degradation occurred above 346 °C, denoting an excellent thermal resistance. There was no significant structural alteration in the active material after microencapsulation and no loss of stability within 60 days, which confirms that this process enables the preservation of freshness and chemical characteristics of tiger nut milk. During 30-90 days, vitamin C contents were stable in the presence or absence of light. Microsphere with tiger nut milk presented a shelf life of 60 days. Total aerobic mesophiles and total fungi counts were below 106 CFU/mL, showing good microbiological stability.

Use of Yarrowia lipolytica Lipase Immobilized in Cell Debris for the Production of Lipolyzed Milk Fat (LMF).

Lipase immobilized on Yarrowia lipolytica cell debris after sonication of yeast cells (LipImDebri) was used in hydrolysis reaction as a novel strategy to produce lipolyzed milk fat (LMF). Extracellular (4732.1 U/L), intracellular (130.0 U/g), and cell debris (181.0 U/g) lipases were obtained in a 4 L bioreactor using residual frying oil as inducer in 24 h fermentation process. LipImDebri showed a good operational stability retaining 70% of lipolytic activity after the second cycle and 40% after the fourth. The highest degree of hydrolysis (28%) was obtained with 500 mg LipImDebri for 6 h of lipolysis of anhydrous milk fat. LMF produced with LipImDebri presented high contents of oleic (35.2%), palmitic (25.0%), and stearic (15.4%) acids and considerable amounts of odor-active short and medium chain fatty acids (C:4⁻C:10) (8.13%).

Biosurfactants from yeasts: characteristics, production and application.

Biosurfactants are surface-active compounds from biological sources, usually extracellular, produced by bacteria, yeast or fungi. Research on biological surfactant production has grown significantly due to the advantages they present over synthetic compounds such as biodegradability, low toxicity, diversity of applications and functionality under extreme conditions. Although the majority of microbial surfactants have been reported in bacteria, the pathogenic nature of some producers restricts the wide application of these compounds. A growing number of aspects related to the production of biosurfactants from yeasts have been the topic of research during the last decade. Given the industrial importance of yeasts and their potential to biosurfactant production, the goal of this chapter is to review the biosurfactants identified up to present, focusing the relevant parameters that influence biosurfactant production by yeasts and its characteristics, revealing the potential of application of such compounds in the industrial field and presenting some directions for the future development of this area, taking into account the production costs.

Optimization of oxygen mass transfer in a multiphase bioreactor with perfluorodecalin as a second liquid phase.

Oxygenation is an important parameter involved in the design and operation of mixing-sparging bioreactors and it can be analyzed by means of the oxygen mass transfer coefficient (k(L)a). The operational conditions of a stirred, submerged aerated 2-L bioreactor have been optimized by studying the influence of a second liquid phase with higher oxygen affinity (perfluorodecalin or olive oil) in the k(L)a. Using k(L)a measurements, the influence of the following parameters on the oxygen transfer rate was evaluated: the volume of working medium, the type of impellers and their position, the organic phase concentration, the aqueous phase composition, and the concentration of inactive biomass. This study shows that the best experimental conditions were achieved with a perfluorodecalin volume fraction of 0.20, mixing using two Rushton turbines with six vertical blades and in the presence of YPD medium as the aqueous phase, with a k(L)a value of 64.6 h(-1). The addition of 20% of perfluorodecalin in these conditions provided a k(L)a enhancement of 25% when pure water was the aqueous phase and a 230% enhancement when YPD medium was used in comparison to their respective controls (no perfluorodecalin). Furthermore it is shown that the presence of olive oil as a second liquid phase is not beneficial to the oxygen transfer rate enhancement, leading to a decrease in the k(L)a values for all the concentrations studied. It was also observed that the magnitude of the enhancement of the k(L)a values by perfluorodecalin depends on the biomass concentration present.