Pupae Oil Research Articles

Microfluidic fatty acid rearrangement in silkworm pupae oil with magnetically responsive lipase under continuous-flow condition

Silkworm pupae-derived structured lipids are expected to promote the absorption of unsaturated fatty acids, however, low efficiency of bioprocess and low reusability of biocatalyst limit the corresponding biocatalysis technology. Thus, a novel strategy combining magnetic response immobilized lipase and continuous-flow microchannel reactor was proposed to modify silkworm pupae oil. The lipase from Aspergillus niger was immobilized on the surface of chitosan cross-linked magnetic nanoparticles, with increased esterification activity from 151.51 to 418.10 U/g due to the hydrophobic microenvironment. In the microchannel, the enzyme activity could be increased to 2371.3 U/g because of the strengthening effect of the microfluidic field. Furthermore, the employment of chitosan cross-linked magnetic nanoparticles leads to good reusability, and the remaining activity could stay above 90% after 13 cycles. Moreover, the immobilized lipase could be removed and loaded easily due to the employment of magnetically responsive nanoparticles. In addition, 2 min was required to rearrange the unsaturated fatty acids, increasing the relative content of sn-1.3 unsaturated fatty acids from 59.91% to 74.8% and sn-2 palmitic acid from 2.69% to 18.88%, which indicated the improved nutritional value of modified silkworm pupae oil. Therefore, the combination of microfluidic field and hydrophobic microenvironment formed by the chitosan layer on the surface of the nanoparticles effectively strengthens the biocatalysis in a solvent-free system, while the developed strategy provides a convenient biocatalysis strategy for the quality improvement of edible insect oil.

Synthesis and Characterization of Epoxidized Silkworm Pupae Oil and Its Application as Polyvinyl Chloride.

More and more industries demand environmental friendliness. Silkworm pupae oil (SPO), extracted from the desilked silkworm pupae, can serve as a promising substrate alternative to use in plasticization. This study aimed to prepare epoxidized silkworm pupae oil (ESPO) and investigate their effects on the thermal stability and plasticization of polyvinyl chloride (PVC) films. A chemo-enzymatic method of ESPO was developed in the presence of Lipase SMG1-F278N and H2O2 in natural deep eutectic solvents (DESs). Lipase SMG1-F278N could initiate the epoxidation reaction effectively at room temperature with a negligible loss of activities 10 batches. A maximum oxirane value of 6.94% was obtained. The formation of oxirane ring in ESPO was confirmed by FTIR and 13C NMR spectra. Moreover, ESPO showed a better thermal stability and lower freezing point than epoxidized soybean oil (ESO). It was demonstrated that ESPO had a good frost resistance. In addition, ESPO showed a significantly improved plasticizing effect on flexible polyvinyl chloride (PVC). Compared with ESO, ESPO could increase the tensile elongation at break effectively. A significantly lower migration rate of plasticizer was observed in PVC plasticized with ESPO.

Enzymatic deacidification of alpha-linolenic acid -enriched oils with negligible change in triacylglycerol composition

In recognition of the demand for fit-for-purpose oil deacidification processes, an industrially feasible enzymatic deacidification system was established for alpha-linolenic acid (ALA)-enriched oils using Lipase G (from Penicillium camembertii) immobilized with ECR8806 resins. The system was first built based on crude silkworm pupal oil (SPO). The advantages of this system include unchanged triacylglycerol composition and content (∼81 %) after deacidification, high reusability for immobilized Lipase G (unchanged deacidification efficiency (∼97 %) after 10 batches), and high retention of desired substances (retained tocopherol, sterol, phosphatidylcholine and phosphatidylethanolamine contents: 87.62 ± 2.29 %, 88.81 ± 2.06 %, 96.94 ± 1.43 % and 95.67 ± 1.09 % respectively). Minimal change was found in efficiency after scaling up the deacidification process (laboratory-scale: 97.03 ± 0.30 %; scale-up: 94.46 ± 0.38 %) under optimal conditions (crude SPO-n-hexane ratio, 1:4 (w:v); free fatty acid-ethanol molar ratio 1:2; enzyme loading, 45 U/g oil; 40 °C for 6 h). And this is the first report on a deacidification process that can preserve largely PC and PE contents in oil. The established deacidification system was further applied to crude flaxseed and perilla seed oil without the change of any conditions and showed good fitness for ALA-enriched oils.

Extraction of Oil from Mulberry and Eri Silkworm Pupae and Analyzing the Physio-Chemical Properties for Commercial Utilization

Silkworm pupal oil was extracted using different solvents from spent dried pupal powder by soxhlet and column extraction methods. The oil content from spent silkworm pupae was maximum recovered from mulberry silkworm pupae (25.90 g/100 g) with hexane solvent in the column extraction method. The better physio-chemical properties viz., density (0.943 g/mL), specific gravity (0.991 g/mL), saponification value (235.147 g KOH/ g oil), iodine value (131.653 g I/ 100 g) and free fatty acids (5.057 %) were observed in the eri silkworm pupal oil, whereas, maximum acid number (1.966 mg KOH/g oil) and peroxide value of (2.44 ppm) was noticed in mulberry silkworm pupal oil. Hence, mulberry silkworm pupae were effectively used for oil extraction by column extraction method using hexane, and these physio-chemical properties of pupal oil were achieved the desired level for utilizing the silkworm pupae oil as commercial utilization

An alternative solution for α-linolenic acid supplements: in vitro digestive properties of silkworm pupae oil in a pH-stat system.

α-Linolenic acid (ALA) is recognised to have a regulatory effect on cardiovascular diseases. Due to the low bioavailability of linseed oil (LINO), which is the most common ALA supplement, it is necessary to find a replacement for ALA supplements that is more easily accepted by the human body. The content of ALA in silkworm pupae oil (SPO) is 32.60 ± 0.67%, and SPO can be substituted as a dietary lipid to meet the demand of the human body. In the present study, a pH-stat system was used to investigate the release degree of free fatty acids (FFAs) from SPO and construct a first-order kinetic model. Digestion experiments in vitro with different lipids showed that the maximum release FFA levels were SPO > SO (soybean oil) > LO (lard oil) > MSO (mulberry seed oil) > LINO, and the first-order kinetic apparent rate constants were LINO > SPO > LO > SO > MSO. Triacylglycerol (TAG) and fatty acid composition are the decisive factors in determining the level of lipid digestion. Therefore, the maximum level of FFAs released from SPO (84.34 ± 1.37%) was much higher than that of LINO (49.78 ± 0.52%) when the hydrolysis rates were 0.2114 s-1 and 0.2249 s-1, respectively. In addition, the smaller emulsion droplet size (609.24 ± 43.46 nm) and weaker surface charge (-17.93 ± 0.42 mV) also resulted in higher levels of SPO under in vitro digestion conditions. Meanwhile, due to low melting and crystallisation temperature, SPO is quickly absorbed by the human body. Overall, SPO can be used as a new alternative for ALA supplements based on its superior digestive properties.

Nutritional targeting modification of silkworm pupae oil catalyzed by a smart hydrogel immobilized lipase

To prepare a nutritional supplement using silkworm pupae oil (SPO) as a feedstock, a microfluidic reactor with a smart hydrogel immobilized lipase was first constructed to reduce the relative content of palmitic acid at sn-1,3 and improve the nutritional function. The effects of flow rate, reaction temperature, and substrate molar ratio were investigated. In vitro digestion and pH-stat models were employed to analyze the digestion feature after the modification of SPO, while HPLC-ELSD, zeta potential, DSC, and TGA were used to evaluate the nutritional function. The relative content of "OOO" and "OPO" type triglycerides was increased by 49.48% and 107.67%, and that of palmitic acid at sn-1,3 was decreased by 49.61% in 10 s. After the verification of the in vitro digestion model, the fatty acid release rate of the modified SPO was significantly improved by 22.07%, indicating the nutritional function improvement of SPO. Therefore, the nutritional function of SPO has been improved successfully by the application of a microchannel reactor with photo-immobilized lipase, which could set a reference for the utilization of insect oil resources.

Two-step enzymatic synthesis of α-linolenic acid-enriched diacylglycerols with high purities from silkworm pupae oil.

In this study, α-linolenic acid-enriched diacylglycerols (ALA-DAGs) were prepared via a two-step enzymatic way by combi-lipase using silkworm pupae oils as substrates. Firstly, several factors including temperature, mass ratio of water to oil, pH and enzyme loading were optimized for the hydrolysis of silkworm pupae oil. The maximum fatty acid content (96.51%) was obtained under the conditions: temperature 40°C, water/oil 3:2 (w/w), pH 7, lipase TL100L loading 400U/g, lipase PCL loading 30U/g. Then, ALA was enriched by urea inclusion, with an increased ALA content of 82.50% being obtained. Secondly, the ALA-enriched silkworm pupae DAG oil (SPDO) was prepared by lipase PCL-catalyzed esterification reaction. After molecular distillation, the final SPDO product contained contents of DAGs (97.01%) and ALA (82.50%). This two-step enzymatic way for production of ALA-DAGs was successfully applied in a 100-fold scale-up reaction. Overall, our study provides a promising way for the preparation of ALA-DAGs.

Effect of silkworm (Bombyx mori) pupae oil supplementation on enteric methane emission and methanogens diversity in sheep

In vitro and in vivo studies were conducted to examine the effect of silkworm pupae oil on methane (CH4) emission and methanogens diversity. Five graded levels (2, 4, 6, 8 and 10%) of silkworm pupae oil were tested in vitro. Eighteen Mandya adult sheep were divided into three groups. All the animals were fed on similar basal diet except the oil supplementation in test groups. Oil level for supplementation was decided on the basis of in vitro study. In vitro study indicated a reduction of 22% in CH4 production with 2% oil supplementation. Animals in test groups were supplemented with oil (2%) either daily (CON) or intermittently (INT) on every alternate week for all the seven days. A significant reduction of 17–20% in enteric CH4 emission (g/d) was achieved due to oil supplementation in sheep. However, No variation was established between test groups CON and INT. In present study, Methanobrevibacter was major genus contributed ∼90% of the total rumen methanogens; whilst Methanobrevibacter gottschalkii was the most abundant methanogens species. Abundance of Methanobrevibacter ruminantium was affected with the oil supplementation. It can be concluded that the silkworm pupae oil at 2% can decrease CH4 emission by 15–20%.

Black soldier fly larvae as a better lipid source than yellow mealworm or silkworm oils for juvenile mirror carp (Cyprinus carpio var. specularis)

A feeding trial was conducted to study the effects of different insect oils on growth performance, lipid metabolism, inflammation and related gene expression in juvenile mirror carp (Cyprinus carpio var. Specularis). Triplicate cages of juvenile mirror carp were fed one of four isonitrogenous and isolipidic diets, including black soldier fly oil (BSFO, 25 g kg−1), silkworm pupae oil (SWPO, 25 g kg−1), yellow mealworm oil (YMO, 25 g kg−1), and a mixture of the three insect oils, BSFO, SWPO and YMO (MIXO, 25 g kg−1) (n = 3). After 59 days, the results showed that weight gain and specific growth rate of fish fed with BSFO and MIXO diets were significantly higher than the fish fed the other two insect oil diets, while feed conversion rate in the same dietary groups was significantly lower than fish fed the SWPO and YMO diets. Intra-peritoneal fat index and adipocyte size in intra-peritoneal fat tissue decreased in the fish fed with BSFO and MIXO compared to fish fed the SWPO and YMO diets. Relative gene expression of fatty acid synthase (FAS) significantly decreased, while peroxisome proliferator-activated receptor-α (PPAR-α) significantly increased in intra-peritoneal fat tissue of fish fed with BSFO and MIXO diets compared with mirror carp fed with SWPO and YMO diets. The activity and transcription of total superoxide dismutase (SOD) significantly increased in the liver of fish fed with BSFO and MIXO than fish fed with SWPO and YMO diets. The content of hepatic maleic dialdehyde (MDA) significantly decreased, while serum globulin (GLO) significantly increased in fish fed with BSFO and MIXO than fish fed with SWPO and YMO diets. Moreover, the transcription of anti-inflammatory cytokine (IL-10) was higher in liver of fish fed with BSFO and MIXO diets. Fish fed with SWPO diet significantly up-regulated the hepatic expression of pro-inflammatory cytokine (IL-1β) and tumor necrosis-α (TNF-α) than fish fed with BSFO, YMO or MIXO diets. Overall, compared to others insect oils source (YMO and SWPO), inclusion of BSFO or the combination of the three oils (MIXO) in the diets positively influence growth performance, lipid metabolism of intra-peritoneal fat, liver antioxidant capacity and inflammatory response of juvenile mirror carp.

Inhibitory effect of modified silkworm pupae oil in PDGF-BB-induced proliferation and migration of vascular smooth muscle cells.

Silkworm pupae oil (SPO) has been reported to have various biological activities in improving blood circulation.However, the protective action of SPO against vascular disorders remains unknown. A new formulation of SPO was prepared through an esterification and saponification process. The composition of unsaturated fatty acids in silkworm pupae oil sodium salt (SPOS) was then analyzed by LC/MS to show α-linolenic acid (11.0%), linoleic acid (73.2%), palmitic acid (3.1%), oleic acid (12.0%), and stearic acid (0.7%). The in vitro studies were performed to find out the efficacy of SPOS on platelet-derived growth factor (PDGF-BB) induced vascular smooth muscle cell (VSMC) migration and proliferation. PDGF-BB (10ng/mL) induced abnormal migration and proliferation of VSMCs, whereas exposure to SPOS (30μg/mL) significantly reduced the PDGF-BB-induced cell migration and proliferation. The extracellular signal-regulated kinase1/2 (ERK1/2) and phosphorylation of ERK1/2 were determined by immunoblot analysis and the ERK1/2 phosphorylation in PDGF-BB-stimulated VSMCs was downregulated by SPOS (30μg/mL) treatment. These results indicate that SPOS may be a helpful and useful agent as a functional food and drug against vascular disorders.

In vitro evaluation of graded level of Silkworm pupae (Bombyx mori) oil on methane production, fermentation characteristics, and protozoal populations.

Aim:The present study was undertaken to evaluate the effect of variable levels of silkworm pupae oil and roughage: concentrate ratio on in vitro methane production, fermentation characteristics, and rumen protozoa population.Materials and Methods:In vitro gas production study (24 h) was performed with graded levels of silkworm pupae oil, namely, 0.5, 1, 2, 4, and 5% of the basal diet and four variable dietary regimes consisting roughage and concentrate in different proportions (70:30, 60:40, 50:50, and 40:60). At the end of incubation, gas samples were analyzed for methane, while fermented rumen liquor was used for protozoa enumeration. A separate set of incubations was carried out for the determination of in vitro dry matter digestibility.Results:Results from the in vitro studies revealed no adverse impact of the silkworm pupae oil supplementation up to 2% level on total gas production. However, supplementation beyond 2% has shown a reduction in total gas production. Incubation with variable levels (0.5-5%) of silkworm pupae oil with different dietary regimes indicated negligible (3-5%) to a substantial reduction (25-30%) on methane production. A graded decrement in methane production was recorded with increasing levels of silkworm pupae oil. Similarly, the protozoal populations were decreased from 10 to 51.5% with graded levels of silkworm pupae oil in different dietary regimes as studies did not reveal any significant (p>0.05) variation between 2 and 4% of oil supplementation.Conclusion:The silkworm pupae oil supplementation at 2% level decreases methane production by 12-15% without any adverse impact on feed fermentation. Oil supplementation may have a more pronounced effect on methane reduction if added to high roughage diet at in vitro conditions. However, in vivo, studies in ruminants are warranted to confirm the methane reduction with silkworm pupae oil supplementation.

Comprehensive Identification of Principal Lipid Classes and Tocochromanols in Silkworm (Antheraea pernyi and Bombyx mori) Pupae Oils

AbstractA comprehensive identification of lipid compositions and tocochromanols in Antheraea pernyi (A. pernyi) and Bombyx mori (B. mori) pupae oil is reported in the present study. Fatty acid profiling shows that both oils contain high levels (79.67% vs 71.11%) of unsaturated fatty acids, especially linoleic acid and linolenic acid. Moreover, linolenic acid is preferentially enriched at the sn‐2 positions of triacylglycerols (TAGs). Liquid chromatograph‐mass spectrometry (LC‐MS) analysis demonstrates that POO (TAG with one palmitoyl and two oleoyls) is the primary TAG form with percentages of 20.18% in A. pernyi and 15.00% in B. mori. The dominating phospholipid species are phosphatidylcholine (PC, 30.40% vs 54.61%) and phosphatidylethanolamine (PE, 34.82% vs 20.39%). Four sterol constituents with total contents of 382.56 ± 3.12 and 371.65 ± 2.98 µg g−1 are identified and analyzed quantitatively. Additionally, the levels of tocochromanols (20.15 ± 0.89 vs 17.15 ± 0.71 mg g−1) are quantified in both silkworm pupae oils. Overall, silkworm oil acts as an enriched source of functional lipids and tocochromanols.Practical Applications: A systematic investigation on the principal lipid classes and tocochromanols of Antheraea pernyi pupae and Bombyx mori pupae oil is reported in this study. The informative data provide supporting evidence for comprehensive utilization of silkworm oil for production of nutritional and healthy products.

Extraction and Characterization of Biofuel from Industrial Waste organic Pupae-Silkworm

The current work carted out of analysis on the production of fuel from pupae fat extracted from silkworm, and exhaustive investigations were conducted to determine the characteristics of obtained fuel and its blends. The oily organic compounds derived from silkworm is effectively adopted to produce biofuel. The soxhlet extractor is utilized here to separate the oil content from pupae and obtained oil processed into biofuel by undertaking the transesterification process using NaOH as a fast reactive agent along with methanol. The rate of biofuel derived from pupae oil has been noticed to be 65- 70 by vol%. The extracted fuels from the transesterification process were mixed with high-speed diesel at a rate of B10, B20, B30 and B40 on volume base. The most important physical and chemical characteristics of generated fuel and their mixture with conventional diesel were examined. The investigation results reveal that the fuel sample B20 satisfies all the requirements of ASTM standards. Pure biofuel shows that the lesser heating value, higher KV, flash point, fire point and density than that of conventional diesel. The blended samples reveal that all the properties are keep moving towards higher value with an increasing percentage of biofuel presence except calorific value. Finally results in evidence that, well suitable biofuel can be generated from organic waste material like silkworm and effectively use it in practical applications.

One hour enzymatic synthesis of structure lipids enriched unsaturated fatty acids from silkworm pupae oil under microwave irradiation

AbstractBACKGROUNDThe silkworm pupae of Bombyx mori L. are considered to be a valuable unsaturated fatty acids (UFAs) resource. Enzymatic transesterification, which can produce structured lipids (SLs), is regarded as a desirable approach to utilize this resource, but requires long reaction time. A method to reduce the reaction time and obtain novel SLs is thus desirable. Hence, microwave irradiation was employed to reduce the reaction time and obtain novel SLs. In addition, high‐performance liquid chromatography with an evaporative light scattering detector was employed to investigate the contribution of the fatty acids (FAs) after microwave irradiation.RESULTSOne hour was required for a 1:5 substrate ratio of silkworm pupae oil (SPO):oleic acid (OA) using a solvent‐free system catalysed by Lipozyme RM IM (7%) at 60 °C with microwave irradiation at 50 W to obtain the novel SLs. The relative content of polyunsaturated FAs glyceride increased from 51.1% to 81.0%, and the relative content of glycerol trioleate (OOO) in SPO obtained in the microwave reactor was twice as high as that in the shaker reactor. In addition, the relative content of OA was increased from 3.9% to 35.8% in total compared with the products from the shaker reactor. Furthermore, the changes of α‐helix relative content of Lipozyme RM IM were observed after the reaction under the microwave irradiation.CONCLUSIONThe results indicated that variations in the FA distribution of enzymatic transesterification reactions caused by microwave irradiation could aid the addition of OA and enrichment of UFAs. © 2019 Society of Chemical Industry

Generation of α-Linolenic Acid Ethyl Ester Microparticles from Silkworm Pupae Oil by Microfluidic Droplet

The instability of polyunsaturated fatty acids to peroxidation often hinders the practical application of oil-based products, and oil-in-water (o/w) emulsions are important components of a wide range of drugs, functional foods and consumer care products. Caffeic acid (CA)-grafted chitosan (CA-g-Ch) was successfully synthesized as a novel wall material and used to embed α-linolenic acid ethyl ester (ALAEE) using microfluidic droplet technology. The results indicated that CA-g-Ch has lower viscosity and stronger emulsification properties than chitosan, and its solution is a Newtonian fluid with good fluidity. When the flow rates of the disperse phase and continuous phase were 0.45 µL/min and 0.75 µL/min, the diameter of the droplets prepared with a 0.25% concentration of Tween 20 was 29 µm, and the droplets had obvious monodispersity. In addition, the droplets were difficult to form normally when the concentration was higher than 1%. The ALAEE microcapsules were easily prepared using freeze-dried droplets. The antioxidant activity of ALAEE microcapsules measured by the DPPH method was 84.96%, which was 7.06 times higher than that observed for untreated ALAEE. Therefore, the monodisperse ALAEE-M prepared by microfluidic microdroplet technology combined with antioxidant wall materials has successfully improved the antioxidant properties of core materials, showing promise for food or drug applications.

Analysis of Chemical Composition of Mulberry Silkworm Pupal Oil with Fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography/Mass Spectrometry (GC/MS) and its Antimicrobial Property

Analysis of Chemical Composition of Mulberry Silkworm Pupal Oil with Fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography/Mass Spectrometry (GC/MS) and its Antimicrobial Property

Microwave-assisted extraction of silkworm pupal oil and evaluation of its fatty acid composition, physicochemical properties and antioxidant activities

Microwave-assisted extraction (MAE) of oil from silkworm pupae was firstly performed in the present research. The response surface methodology was applied to optimize the parameters for MAE. The yield of oil by MAE was 30.16% under optimal conditions of a mixed solvent consisting of ethanol and n-hexane (1:1, v/v), microwave power (360W), liquid to solid ratio (7.5/1mL/g), microwave time (29min). Moreover, oil extracted by MAE was quantitatively (yield) and qualitatively (fatty acid profile) similar to those obtained using Soxhlet extraction (SE), but oil extracted by MAE exhibited favourable physicochemical properties and oxidation stability. Additionally, oil extracted by MAE had a higher content of total phenolic, and it showed stronger antioxidant activities. Scanning electron microscopy revealed that microwave technique efficiently promoted the release of oil by breaking down the cell structure of silkworm pupae. Therefore, MAE can be an effective method for the silkworm pupal oil extraction.

Silkworm pupae oil exerts hypercholesterolemic and antioxidant effects in high-cholesterol diet-fed rats.

Silkworm pupae is a good resource of edible oil that is especially rich in unsaturated fatty acids and is considered to be an excellent dietary supplement for hyperlipidemia. Groups fed a high-cholesterol diet (HCD) with silkworm pupae oil (SPO) supplementation (1, 2, or 4 mL kg-1 day-1 ) orally had significantly lower levels of serum total cholesterol (P < 0.05) and low-density lipoprotein cholesterol (P < 0.05) compared to the HCD group. With regard to antioxidant parameters, except for levels of glutathione peroxidase (GSH-Px) in the liver, 2 and 4 mL kg-1 day-1 of SPO supplementation leaded to higher total antioxidant capacity (P < 0.05), superoxide dismutase (P < 0.05) and GSH-Px levels (P < 0.05), as well as lower malondialdehyde levels (P < 0.05), both in serum and liver compared to the HCD group. The results of the present study indicate that supplementation with SPO can improve lipid profiles and alleviate oxidative stress in high-cholesterol diet-fed rats. © 2016 Society of Chemical Industry.

APA-style human milk fat analogue from silkworm pupae oil: Enzymatic production and improving storage stability using alkyl caffeates.

Silkworm pupae oil derived from reeling waste is a rich source of α-linolenic acid (ALA), which has multipal applications. ALAs were added in sn-1, 3 positions in a triacylglycerol (TAG) to produce an APA-human milk fat analogues (APA-HMFAs, A: α-linolenic acid, P: palmitic acid). The optimum condition is that tripalmitin to free fatty acids of 1:12 (mole ratio) at 65 °C for 48 h using lipase Lipozyme RM IM. Results show that, the major TAG species that comprised APA-HMFAs were rich in ALA and palmitic acid, which contained 64.52% total unsaturated fatty acids (UFAs) and 97.05% PA at the sn-2 position. The melting point of APA was −27.5 °C which is much lower than tripalmitin (40.5 °C) indicating more plastic character. In addition, the practical application of alkyl caffeates as liposoluble antioxidants in APA was developed. Alkyl caffeate showed a superior IC50 (1.25–1.66 μg/mL) compared to butyl hydroxy anisd (1.67 μg/mL) and L-ascorbic acid-6-palmitate (L-AP) (1.87 μg/mL) in DPPH analysis. The addition of ethyl caffeate to oil achieved a higher UFAs content (73.58%) at high temperatures. Overall, APA was obtained from silkworm pupae oil successfully, and the addition of caffeates extended storage ranges for APA-HMFAs.

Structured lipids enriched with unsaturated fatty acids produced by enzymatic acidolysis of silkworm pupae oil using oleic acid

Desilked silkworm (Bombyx mori L.) pupae oil has been identified as a valuable source of unsaturated fatty acids (UFAs). However, direct consumption is a food safety issue due to the presence of sn‐1,3 triacylglycerols (TAGs), including palmitic acid (PA). A simple, selective and safe conversion to structured triacylglycerols (STAGs) with high UFA content is highly desirable. Novel STAGs with low PA and high α‐linolenic acid (ALA), oleic acid (OA) and linoleic acid (LA) content were synthesized from silkworm pupae oil using a solvent‐free system catalyzed by Lipozyme RM IM. Crystallization and melting profiles were determined using thermograms, and optimal conditions involved an enzyme load of 7%, a silkworm pupae oil TAG to OA molar ratio of 1:5, and a reaction temperature of 60°C. The content of PA and stearic acid decreased from 41.04 to 20.11%, while UFAs increased from 61.12 to 77.88%. The STAGs exhibited lower crystallization (−15.44°C) and melting (−23.47°C) profiles than TAGs (4.64 and −5.58°C, respectively).Practical applicationsThe presented methods using a solvent‐free system enable STAGs to be synthesized using a natural substrate (desilked silkworm pupae oil). A simple, selective and safe conversion to STAGs with high UFA content and low PA content is highly desirable. This STAG is rare in nature and chemical synthesis is cumbersome. This STAG could be applied as a clinical treatment for nutritional enhancement with a beneficial effect on human health because of the high content of the ALA.Novel structure triacylglycerols (STAGs) with low palmitic acid and rich in oleic acid and linoleic acid were synthesized from silkworm pupae oil and oleic acid, through solvent‐free enzymatic interesterification catalyzed by Lipozyme RM IM. Under the optimal conditions, the content of palmitic acid and stearic acid decreased from 41.04 to 20.11% in the sn‐1, 3 positions, and the content of unsaturated fatty acids (including palm stearin, oleic acid, linoleic acid and α‐linolenic acid) increased from 61.12 to 77.88%. The STAGs could be added into milk fat substitutes, which may be useful as nutrition enhancers for infants and may decrease obesity.