Production of MLM-Type Structured Lipids Catalyzed by Immobilized Heterologous Rhizopus oryzae Lipase

A comprehensive review of lipase-catalyzed acidolysis as a method for producing structured glycerides

The production of structured lipids is a current trend in food technology in order to enhance the properties of fats and oils. Lipases have been utilized in many instances for this purpose, in most examples in an immobilized form. In this review, after discussing the different strategies to produce artificial lipids using lipases (esterification, transesterification, interesterification), we have focused on acidolysis. The reaction commences with hydrolysis at one position of the triglyceride molecule and is followed by the esterification between the released hydroxyl group and the target fatty acid (although other carboxylic acids can be used, such as phenolic acid derivatives). This means that water plays a double role, as substrate in the first step and as an undesired by-product in the second one. Therefore, the control of water activity becomes critical in these reactions. This review discusses the advantages, possibilities and drawbacks of this strategy to produce tailor-made designed lipids, summarizing many of the papers related to this strategy. The summarized results show the complexity of this reaction that can make the understanding and reproducibility of the reactions complex if there are no strict controls of all parameters determining the final yields.

Synthesis of dietary lipids from pumpkin (Cucurbita pepo. L) oil obtained by enzymatic extraction: a sustainable approach

This study aimed to assess the nutritional properties of dietary lipids obtained through the modification of aqueous enzymatically extracted pumpkin seed (Cucurbita pepo. L) oil. The optimal growth conditions for producing pectinase using strain Aspergillus sp. 391 were determined, and partial characterization of pectinase and commercial cellulase was conducted. The enzymatic extraction was performed at pH 4.0, 50 °C, for 24 h, using a combination of pectinase and cellulase for optimum effectiveness. The crude oil obtained was analyzed for acid, peroxide, and fatty acid composition. The study found a high amount of unsaturated fatty acids, mainly linoleic acid (C18:2), and a 59% oil recovery rate. Subsequently, this oil was subjected to enzymatic acidolysis with capric acid in solvent-free media, catalyzed by lipase Lipozyme RM IM®, resulting in a product with a higher incorporation degree (48.39 ± 0.5 mol%), observed after 24 h at 60 °C using molar ratio oil:acid capric of 1:9 (run 4). The nutritional properties of this oil were improved.

Enzymatic Synthesis Process of EPA- and DHA-Enriched Structured Acylglycerols at the sn-2 Position Starting from Commercial Salmon Oil and Concentrated by Response Surface Methodology under Supercritical Conditions

The bioavailability of n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFAs) has shown to be greatly influenced by their location in the triacylglycerol backbone. Therefore, the synthesis of structured acylglycerols (SAcyl), which include eicosapentaenoic acids (EPAs) or docosahexaenoic acids (DHAs) at the sn-2 position, has attracted a great interest. The objective of this study was to optimize the synthesis process of a SAcyl from commercial refined salmon oil and an EPA/DHA concentrate in order to enhance the positioning of EPA and DHA in the sn-2 location of the glycerol moiety. For this purpose, immobilized lipase B from Candida antarctica (nonspecific) was used for the acidolysis process under the CO2 supercritical condition. As a result of carrying out a Draper-Lin composite design through the response surface methodology of 18 experiments, an optimized extraction including SAcyl compounds was obtained. Mass spectrometry (MALDI-TOF) analysis was employed to identify the EPA/DHA location at the sn-2 position in the resulting glycerol moiety. In the fraction obtained, an increase in the EPA and DHA content at the sn-2 position was detected. Remarkably, the optimized SAcyl obtained after 6 h, 82 bar, and 60 °C led to the highest EPA/DHA yield at the sn-2 position in the resulting molecule.

Effect of Structured Phenolic Lipids with EPA/DHA and Gallic Acid against Metabolic-Associated Fatty Liver Disease (MAFLD) in Mice

Obesity is the leading risk factor for developing metabolic (dysfunction)-associated fatty liver disease (MAFLD). The food industry has an essential role in searching for new strategies to improve primary food sources to revert some of the metabolic alterations induced by obesity. There is consistent evidence that long-chain polyunsaturated fatty acids (n-3 LCPUFA) belonging to the n-3 series, i.e., eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) acids, could revert some alterations associated with obesity-induced metabolic diseases. A relevant tool is the synthesis of structured acylglycerols (sAG), which include EPA or DHA at the sn-2 position. On the other hand, it has been reported that a crucial role of antioxidants is the reversion of MAFLD. In this work, we studied the effects of new molecules incorporating gallic acid (GA) into EPA/DHA-rich structured lipids. Mice were fed with a high-fat diet (60%) for three months and were then divided into five groups for supplementation with sAG and sAG structured with gallic acid (structured phenolic acylglycerols, sPAG). sPAG synthesis was optimized using a 2²-screening factorial design based on the response surface methodology (RSM). Our results show that treatment of sPAG was effective in decreasing visceral fat, fasting glycemia, fasting insulin, suggesting that this new molecule has a potential use in the reversal of MAFLD-associated alterations.

Physicochemical properties of a new structural lipid from the enzymatical incorporation of flaxseed oil into mutton tallow

This study evaluated the physio-chemical properties of a structural lipid (SL) obtained by the enzymatical incorporation of flaxseed oil into mutton tallow (MT). By measuring the melting point, colour, safety, fatty acids, apparent viscosity, shear stress and volatile compounds of the samples, the results showed that compared to MT, SL exhibited lower L∗(lightness) value, melting point, apparent viscosity and shear stress (p < 0.05). Noteworthy, the Saturated fatty acids (SFA)content of MT was reduced from 61.46% to 25.49% (p < 0.05), although SL was found to be more prone to oxidation during storage. The clearest discrepancy in volatile compounds was the increase of heterocyclic compounds in SL. In summary, improving the edible properties of animal fats by adding vegetable oils is an effective solution, and SL may have a great potential to be developed into a high-quality product with improved nutritional composition of animal fat.

Enzymatic synthesis of capric acid-rich structured lipids and their effects on mice with high-fat diet-induced obesity

The objective of this study was to produce structured lipids (SLs) by enzymatic acidolysis using Rhizopus oryzae lipase covalently immobilized in a low-cost material. Grape seed oil was used to synthesize SLs containing the medium-chain fatty acid (C10:0) capric acid. SL synthesis led to 38.8% medium-chain fatty acid incorporation with 5 reuses of the enzymatic derivative. The reaction conditions for the synthesis of MLM-TAGs (triacylglycerols with one long- and two medium-chain acyl residues) were at a molar ratio of fatty acid:oil of 3:1, performed at 40 °C and lipase immobilized load of 5% (w/w). The in vivo effects of SLs were studied in Swiss mice fed premade diets: control (C) diet, high-fat diet (HFD) with 100% lipid content as lard, HFD with 50% lipid content as grape seed oil (HG) or HFD with 50% lipid content as capric acid-containing SLs produced from grape seed oil (HG-MCT). Mice from HG and HG-MCT groups had decreases in body weight gain and reductions in the weights of white adipose tissues. In addition, HG and HG-MCT mice had low plasma levels of glucose and total cholesterol, and improvements in the glucose tolerance. HG and HG-MCT diets have remarkable antioxidant properties, since low plasma levels of TBARS (thiobarbituric acid reactive substances, biomarkers of lipid peroxidation) were found in mice fed these diets. Interestingly, TBARS levels in HG-MCT mice were further decreased than values of HG mice. Mice fed HG and HG-MCT diets also showed preservation in the activity of the antioxidant enzyme paraoxonase 1. Both HG and HG-MCT diets promoted reduction of IL-6 and IL-10 production by splenocytes. The capric acid-containing SLs produced from grape seed oil emerges as a functional oil capable to mitigate obesity complications resulting from oxidative stress and inflammation.

Synthesis of EPA- and DHA-Enriched Structured Acylglycerols at the sn-2 Position Starting from Commercial Salmon Oil by Enzymatic Lipase Catalysis under Supercritical Conditions

There is consistent evidence that long-chain polyunsaturated fatty acids (LCPUFA) belonging to the n-3 series, i.e., eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) acids, decrease the risk of heart, circulatory and inflammatory diseases. Furthermore, the bioavailability of such fatty acids has been shown to depend on their location in triacylglycerol (TG) molecules at the sn-2 position. Consequently, great attention has been accorded to the synthesis of structured acylglycerols (sAG), which include EPA or DHA at the sn-2 position. The aim of this work was to synthesize sAG starting from deodorized refined commercial salmon oil. For this, immobilized lipase B from Candida antarctica (nonspecific) was used as a catalyst for the intra–interesterification process under CO₂ supercritical conditions (CO₂SC). According to the CO₂SC reaction time, three different fractions including sAG compounds were obtained. The location of EPA and DHA at the sn-2 position in the resulting glycerol backbone was identified by mass spectrometry (MALDI-TOF) analysis. In all fractions obtained, a marked decrease in the starting TG content was observed, while an increase in the DHA content at the sn-2 position was detected. The fraction obtained after the longest reaction time period (2 h) led to the highest yield of sn-2 position DHA in the resulting sAG molecule.

Medium chain triglyceride and medium-and long chain triglyceride: metabolism, production, health impacts and its applications - a review

Structured lipid is a type of modified form of lipid that is "fabricated" with the purpose to improve the nutritional and functional properties of conventional fats and oils derived from animal and plant sources. Such healthier choice of lipid received escalating attention from the public for its capability to manage the rising prevalence of metabolic syndrome. Of which, medium-chain triacylglycerol (MCT) and medium-and long-chain triacylglycerol (MLCT) are the few examples of the "new generation" custom-made healthful lipids which are mainly composed of medium chain fatty acid (MCFA). MCT is made up exclusively of MCFA whereas MLCT contains a mixture of MCFA and long chain fatty acid (LCFA), respectively. Attributed by the unique metabolism of MCFA which is rapidly metabolized by the body, MCFA and MCT showed to acquire multiple physiological and functional properties in managing and reversing certain health disorders. Several chemically or enzymatically oils and fats modification processes catalyzed by a biological or chemical catalyst such as acidolysis, interesterification and esterification are adopted to synthesis MCT and MLCT. With their purported health benefits, MCT and MLCT are widely being used as nutraceutical in food and pharmaceutical sectors. This article aims to provide a comprehensive review on MCT and MLCT, with an emphasis on the basic understanding of its structures, properties, unique metabolism; the current status of the touted health benefits; latest routes of production; its up-to-date applications in the different food systems; relevant patents filed and its drawbacks.

Rhizopus oryzae Lipase, a Promising Industrial Enzyme: Biochemical Characteristics, Production and Biocatalytic Applications

Lipases are biocatalysts with a significant potential to enable a shift from current pollutant manufacturing processes to environmentally sustainable approaches. The main reason of this prospect is their catalytic versatility as they carry out several industrially relevant reactions as hydrolysis of fats in water/lipid interface and synthesis reactions in solvent-free or non-aqueous media such as transesterification, interesterification and esterification. Because of the outstanding traits of Rhizopus oryzae lipase (ROL), 1,3-specificity, high enantioselectivity and stability in organic media, its application in energy, food and pharmaceutical industrial sector has been widely studied. Significant advances have been made in the biochemical characterisation of ROL particularly in how its activity and stability are affected by the presence of its prosequence. In addition, native and heterologous production of ROL, the latter in cell factories like Escherichia coli, Saccharomyces cerevisiae and Komagataella phaffii (Pichia pastoris), have been thoroughly described. Therefore, in this review, we summarise the current knowledge about R. oryzae lipase (i) biochemical characteristics, (ii) production strategies and (iii) potential industrial applications.

Valorization of Glycerol through the Enzymatic Synthesis of Acylglycerides with High Nutritional Value

The production of specific acylglycerides from the selective esterification of glycerol is an attractive alternative for the valorization of this by-product of the biodiesel industry. In this way, products with high added value are generated, increasing the profitability of the overall process and reducing an associated environmental threat. In this work, nutritional and medically interesting glycerides were obtained by enzymatic esterification through a two-stage process. In the first stage, 1,3-dicaprin was obtained by the regioselective esterification of glycerol and capric acid mediated by the commercial biocatalyst Lipozyme RM IM. Under optimal reaction conditions, 73% conversion of fatty acids and 76% selectivity to 1,3-dicaprin was achieved. A new model to explain the participation of lipase in the acyl migration reaction is presented. It evaluates the conditions in the microenvironment of the active site of the enzyme during the formation of the tetrahedral intermediate. In the second stage, the esterification of the sn-2 position of 1,3-dicaprin with palmitic acid was performed using the lipase from Burkholderia cepacia immobilized on chitosan as the biocatalyst. A biocatalyst containing 3 wt % of lipase showed good activity to esterify the sn-2 position of 1,3-dicaprin. A mixture of acylglycerides consisting mainly of capric acid esterified at sn-1 and sn-3, and of palmitic acid at the sn-2 position was obtained as the reaction product. The influence of the biocatalyst mass, the reaction temperature, and the molar ratio of substrates were evaluated for this reaction using a factorial design. Simple models were used to adjust the consumption of reagents and the generation of different products. The reaction product contained between 76% and 90% of acylglycerides with high nutritional value, depending on the reaction conditions.

Lipase-Catalyzed Synthesis of Structured Lipids at Laboratory Scale

In this chapter, some examples of laboratory protocols to produce functional structured lipids, namely, human milk fat substitutes, dietetic triacylglycerols, and interesterified fat blends with improved nutritional and rheological properties, catalyzed either by immobilized commercial or noncommercial lipase preparations, are presented. In addition to batch synthesis, the continuous production in packed- or fluidized-bed bioreactors is addressed, as well as the evaluation of operational stability of the biocatalysts used (either in batch reuses or in continuous mode).

Screening of Lipases with Unusual High Activity in the sn-2 Esterification of 1,3-Dicaprin under Mild Operating Conditions

In this work, the synthesis of acylglycerides with high nutritional value was carried out by enzymatic esterification at sn-2 position of 1,3-dicaprin with palmitic acid. A comparative study of the performance of several biocatalysts according to the obtained products was carried out. The results obtained with several of the biocatalysts evaluated are very interesting, and it would be possible to use them to obtain a mixture of acylglycerides to act as a fat substitute. The final product was composed of about 90% of nutritionally attractive glycerides. These glycerides were medium-chain length triglycerides, medium-long chain triglycerides (mainly triglycerides with medium chain fatty acids at sn-1 and sn-3 positions and long chain fatty acid at sn-2 position), and 1,3-diglycerides. Pseudomonas fluorescens lipase and Burkholderia cepacia lipase immobilized on chitosan demonstrated unusual high activity in the sn-2 esterification of 1,3-dicaprin with palmitic acid at 45 °C and 12 h with 33% yield to 1,3-dicaproyl-2-palmitoyl glycerol. Burkholderia cepacia lipase has the advantage of being immobilized; however, BCL/chitosan has the advantages of being immobilized and therefore its easy recovery from the reaction media.

Biodiesel production from crude Jatropha oil catalyzed by non-commercial immobilized heterologous Rhizopus oryzae and Carica papaya lipases

The aim of this study was to evaluate the feasibility of biodiesel production by transesterification of Jatropha oil with methanol, catalyzed by non-commercial sn-1,3-regioselective lipases. Using these lipases, fatty acid methyl esters (FAME) and monoacylglycerols are produced, avoiding the formation of glycerol as byproduct. Heterologous Rhizopus oryzae lipase (rROL) immobilized on different synthetic resins and Carica papaya lipase (rCPL) immobilized on Lewatit VP OC 1600 were tested. Reactions were performed at 30°C, with seven stepwise methanol additions. For all biocatalysts, 51-65% FAME (theoretical maximum=67%, w/w) was obtained after 4h transesterification. Stability tests were performed in 8 or 10 successive 4h-batches, either with or without rehydration of the biocatalyst between each two consecutive batches. Activity loss was much faster when biocatalysts were rehydrated. For rROL, half-life times varied from 16 to 579h. rROL on Lewatit VPOC 1600 was more stable than for rCPL on the same support.

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications

Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

Potential use of avocado oil on structured lipids MLM-type production catalysed by commercial immobilised lipases

Structured Lipids are generally constituents of functional foods. Growing demands for SL are based on a fuller understanding of nutritional requirements, lipid metabolism, and improved methods to produce them. Specifically, this work was aimed to add value to avocado oil by producing dietary triacylglycerols (TAG) containing medium-chain fatty acids (M) at positions sn-1,3 and long-chain fatty acids (L) at position sn-2. These MLM-type structured lipids (SL) were produced by interesterification of caprylic acid (CA) (C8:0) and avocado oil (content of C18:1). The regiospecific sn-1,3 commercial lipases Lipozyme RM IM and TL IM were used as biocatalysts to probe the potential of avocado oil to produce SL. Reactions were performed at 30–50°C for 24 h in solvent-free media with a substrate molar ratio of 1∶2 (TAG:CA) and 4–10% w/w enzyme content. The lowest incorporation of CA (1.1% mol) resulted from Lipozyme RM IM that was incubated at 50°C. The maximum incorporation of CA into sn-1,3 positions of TAG was 29.2% mol. This result was obtained at 30°C with 10% w/w Lipozyme TL IM, which is the highest values obtained in solvent-free medium until now for structured lipids of low-calories. This strategy opens a new market to added value products based on avocado oil.

Biocatalytic behaviour of immobilized Rhizopus oryzae lipase in the 1,3-selective ethanolysis of sunflower oil to obtain a biofuel similar to biodiesel

A new biofuel similar to biodiesel was obtained in the 1,3-selective transesterification reaction of sunflower oil with ethanol using as biocatalyst a Rhizopus oryzae lipase (ROL) immobilized on Sepiolite, an inorganic support. The studied lipase was a low cost powdered enzyme preparation, Biolipase-R, from Biocon-Spain, a multipurpose additive used in food industry. In this respect, it is developed a study to optimize the immobilization procedure of these lipases on Sepiolite. Covalent immobilization was achieved by the development of an inorganic-organic hybrid linker formed by a functionalized hydrocarbon chain with a pendant benzaldehyde, bonded to the AlPO4 support surface. Thus, the covalent immobilization of lipases on amorphous AlPO4/sepiolite (20/80 wt %) support was evaluated by using two different linkers (p-hydroxybenzaldehyde and benzylamine-terephthalic aldehyde, respectively). Besides, the catalytic behavior of lipases after physical adsorption on the demineralized sepiolite  was also evaluated. Obtained results indicated that covalent immobilization with the p-hydroxybenzaldehyde linker gave the best biocatalytic behavior. Thus, this covalently immobilized lipase showed a remarkable stability as well as an excellent capacity of reutilization (more than five successive reuses) without a significant loss of its initial catalytic activity. This could allow a more efficient fabrication of biodiesel minimizing the glycerol waste production.

New biofuel integrating glycerol into its composition through the use of covalent immobilized pig pancreatic lipase

By using 1,3-specific Pig Pancreatic lipase (EC 3.1.1.3 or PPL), covalently immobilized on AlPO(4)/Sepiolite support as biocatalyst, a new second-generation biodiesel was obtained in the transesterification reaction of sunflower oil with ethanol and other alcohols of low molecular weight. The resulting biofuel is composed of fatty acid ethyl esters and monoglycerides (FAEE/MG) blended in a molar relation 2/1. This novel product, which integrates glycerol as monoacylglycerols (MG) into the biofuel composition, has similar physicochemical properties compared to those of conventional biodiesel and also avoids the removal step of this by-product. The biocatalyst was found to be strongly fixed to the inorganic support (75%). Nevertheless, the efficiency of the immobilized enzyme was reduced to half (49.1%) compared to that of the free PPL. The immobilized enzyme showed a remarkable stability as well as a great reusability (more than 40 successive reuses) without a significant loss of its initial catalytic activity. Immobilized and free enzymes exhibited different reaction mechanisms, according to the different results in the Arrhenius parameters (Ln A and Ea). However, the use of supported PPL was found to be very suitable for the repetitive production of biofuel due to its facile recyclability from the reaction mixture.