Pupae Oil Research Articles

An effective GC method for the determination of the fatty acid composition in silkworm pupae oil using a two-step methylation process

In search of an accurate and effective method to determine fatty acid composition in silkworm pupae oils, five methylation methods were evaluated for use in the gas chromatographic (GC) quantitation of fatty acid methyl esters (FAMEs), including one-step esterification catalyzed by an acidic (H2SO4 and BF3) or alkali catalyst (KOH and NaOCH3) and a two-step procedure catalyzed successively by KOH and H2SO4. These methods were comparatively adopted to quantify FAMEs in silkworm pupae oil using GC-MS and GC and then validate their precision, stability and average recovery rates. The results indicated that compared with the other four methyl esterification methods, two-step methylation effectively improves the synthesis yield of FAMEs, conserves agents, and eliminates the usage of potential harmful reagents. The proposed GC method has been validated, shows good accuracy and precision, and has been applied successfully to the quantification of FAMEs in several varieties of silkworm pupae oils. The short analytical run time leads to low costs and a fast chromatographic procedure. In summary, two-step pretreatment had superior performance, providing technical references for the determination and analysis of fatty acids in other oils.

Enrichment process for α‐linolenic acid from silkworm pupae oil

The desilked silkworm (Bombyx mori L.) pupae oil is a good source of α‐linolenic acid (ALA), but selectively enriching ALA is a great technical challenge due to the presence of multiple analogues such as linoleic acid and oleic acid. To set up a simple, highly selective and low‐cost combinative inclusion process for obtaining ALA concentrate from silkworm pupae oil, the effects of β‐cyclodextrin (β‐CD) inclusion parameters on the purity and recovery of polyunsaturated fatty acid (PUFA) were investigated; then, four types of combinative processes using β‐CD and/or urea were compared. The results indicated that a two‐stage combinative inclusion process was established. In the first stage, when the volume ratio of β‐CD‐saturated solution to free fatty acids ethanol solution was 9 v/v, the dispersion temperature and time were 60°C and 1.5 h, the freezing temperature and time were −10°C and 15 h, and the purity of ALA was raised from 15.0 to 47.6% with a recovery of 39.4%. Then, the purity of ALA was further increased to 67.4% in the second‐stage operation with a corresponding recovery of 34.8% using urea complexation.

Biodiesel Production from Silkworm Pupae Oil Using Solid Base Catalyst

How to dispose large amounts of free fatty acids of the desilked silkworm (Bombyx mori L.) pupae oil in a suitable way have attracted considerable attention. The feasibility of biodiesel production from the desilked silkworm pupae oil using Na2O•SiO2•5H2O as a solid base catalyst was investigated, and the experimental conditions (i. e. molar ratio of methanol to oil, catalyst concentration, reaction time and reaction temperature) were studied. The experimental results indicated that Na2O•SiO2•5H2O possesses high catalytic activity towards the synthesis of biodiesel from the desilked silkworm pupae oil. The methyl esters conversion of up to 73 % for free fatty acids of the desilked silkworm pupae oil was achieved using the following reaction conditions: catalyst concentration 5 %, the molar ratio of methanol to oil 6:1, reaction temperature 70 °C, and retention time 8 h. Therefore, the desilked silkworm pupae oil is proved to be a new biodiesel source in a more sustainable way.

Supercritical Carbon Dioxide Extraction of the Oak Silkworm (Antheraea pernyi) Pupal Oil: Process Optimization and Composition Determination

Supercritical carbon dioxide (SC-CO2) extraction of oil from oak silkworm pupae was performed in the present research. Response surface methodology (RSM) was applied to optimize the parameters of SC-CO2 extraction, including extraction pressure, temperature, time and CO2 flow rate on the yield of oak silkworm pupal oil (OSPO). The optimal extraction condition for oil yield within the experimental range of the variables researched was at 28.03 MPa, 1.83 h, 35.31 °C and 20.26 L/h as flow rate of CO2. Under this condition, the oil yield was predicted to be 26.18%. The oak silkworm pupal oil contains eight fatty acids, and is rich in unsaturated fatty acids and α-linolenic acid (ALA), accounting for 77.29% and 34.27% in the total oil respectively.

Eri silkworm: a source of edible oil with a high content of α‐linolenic acid and of significant nutritional value

The study was undertaken to provide value addition to spent eri silkworm as an alternative source of edible oil for the food and feed industry by carrying out a short-term nutritional and toxicological evaluation of eri silkworm pupae oil using Wistar NIN rats. Growth performance of rats fed either sunflower oil (Control) or eri silkworm pupae oil (Experimental) was comparable. Histopathological examination of the various tissues showed no signs of toxicity even after feeding the eri silkworm oil for 18 weeks. Serum cholesterol and triglyceride was significantly reduced (P < 0.05) while high-density lipoprotein cholesterol was significantly increased (P < 0.05) which is attributed to the high α-linolenic acid content of eri silkworm oil. The study showed that eri silkworm pupae oil is safe and nutritionally equivalent to commonly used vegetable oils. Eri silkworm pupae can be harvested to provide a cost effective alternative edible oil that can be used to nutritional advantage in the food and feed industry. Therefore eri silkworm and its host plants offer an excellent example of multiple product crops and of sustainable agricultural practice with excellent opportunity for economic and nutritional benefits.

Isolation and analysis of natural compounds from silkworm pupae and effect of its extracts on alcohol detoxification

AbstractSilkworm pupae have much potential and many applications as a natural medicine to promote human health. However, their chemical components have not been fully characterized or understood. HPLC analysis was conducted to determine the content ratio (%) of individual amino acids in total protein of the pupae. It showed that glutamic acid (18.3%), histidine (14.6%) and alanine (10.2%) are the most common amino acids in silkworm pupae. Fatty acid composition of silkworm pupae oil was revealed by high‐pressure liquid chromatography and gas chromatography – mass spectroscopy analyses. They contain a high ratio of essential fatty acids, [α‐linolenic acid (ω‐3 fatty acid]+ linoleic acid) (49.0%), and also contain non‐essential fatty acids, oleic acid (19.9%), palmitoleic acid (2.5%), palmitic acid (19.7%), stearic acid (8.6%), and eicosapentaenoic acid (EPA) (0.3%). In addition, they also contain antioxidants, quercetin diglucoside and nutritionally important riboflavin (vitamin B2). This study suggests that silkworm pupae are a nutritionally valuable food product and are applicable as cosmetic components with essential amino acids, essential fatty acids, antioxidants and vitamins. The animal experiment showed that alcohol dehydrogenase (ADH) activity was significantly higher in the liver of mice orally administered with 0.5 mg/mL of silkworm extract and alcohol than with commercial Dawn808™ and alcohol, indicating that silkworm pupae extracts have alcohol detoxification activity.

New Polar Constituents in the Pupae of the Silkworm Bombyx mori L. (II): Developmental Changes of the Constituents

A correlation between the quantitative changes in L-methionine analogs, the ratio of D-serine/L-serine during the pupal stage, and metamorphosis was observed. The glycoside appearing at low blood sugar values during the pupal stage was isolated and characterized as D-glucosyl-L-tyrosine. (1)H-NMR indicated the appearance and increase of this glycoside, and Mirrorcle Ray CV4 equipment was used to take X-ray pictures of the pupal bodies. The results indicate that γ-cyclic di-L-glutamate and L-methionine sulfone might be concerned with ammonia assimilation in the pupae, and that D-glucosyl-L-tyrosine served as a switch for the fatty acid (pupal oil) dissimilation hybrid system.

Process optimization for the enrichment of α-linolenic acid from silkworm pupal oil using response surface methodology.

-Linolenic acid (ALA) was widely used in food and pharmaceutical industry, as an important medical material. In the present study, the mixed fatty acids (MFAs) extracted from desilked silkworm pupal oil were used raw materials for enriching ALA, using urea clathration method; their preparation process was optimized by response surface methodology (RSM). The research results indicated that the enrichment of ALA produced, by using urea clathration method from desilked silkworm pupal oil was effectively enhanced by RSM. Three parameters of the process for enriching ALA were optimized as follows, using RSM: the ratio of saturated urea/EtOH solution to MFAs was 2:1 (v/v); clathration temperature, 4°C and clathration time, 2 h. The adequately high R2 value, 0.9674 (adjusted R2 = 0.9086) indicated the statistical significance of the model. The purity of ALA after optimization was 31.87%, while predicted value, 35.60%. In conclusion, enrichment conditions optimization to enhance purity of ALA from the MFAs of desilked silkworm pupal oil can be easily and effectively done by RSM. The developed enrichment process of ALA indicated desilked silkworm pupal oil as a potential raw material for producing ALA.

Optimization of supercritical carbon dioxide extraction of silkworm pupal oil applying the response surface methodology

Supercritical carbon dioxide extraction (SC-CO 2) of oil from desilked silkworm pupae was performed. Response surface methodology (RSM) was applied to optimize the parameters of SC-CO 2 extraction. The effects of independent variables, including pressure, temperature, CO 2 flow rate, and extraction time, on the yield of oil were investigated. The statistical analysis showed that the pressure, extraction time, and the quadratics of pressure, extraction time, and CO 2 flow rate, as well as the interactions between pressure and temperature, and temperature and flow rate, showed significant effects on oil yield. The optimal extraction condition for oil yield within the experimental range of the variables researched was at 324.5 bar, 39.6 °C, 131.2 min, and 19.3 L/h. At this condition, the yield of oil was predicted to be 29.73%. The obtained silkworm pupal oil contained more than 68% total unsaturated fatty acids, and alpha-linolenic acid (ALA) accounted for 27.99% in the total oil.

Isolation and Characterization of Neutral Lipids of Desilked Eri Silkworm Pupae Grown on Castor and Tapioca Leaves

The neutral lipid of desilked eri silkworm pupae (Samia cynthia ricini) grown on two different host plants, castor (Ricinus communis Linn.) and tapioca (Manihot utilizsima Phol.) leaves, was extracted with hexane. The oil content in pupae was estimated to be in the range of 18-20% (dry basis). The pupal oil was found to be enriched with alpha-linolenic acid (ALA) with palmitic acid as the second major fatty acid. The level of ALA in the oil of silkworm pupae was found to be significantly higher (P < 0.001) when grown on tapioca (58.3%) as compared to those grown on castor (42.9%). Other chemical parameters such as percent free fatty acid, peroxide value, phosphorus content, percent unsaponifiable matter, and composition of sterols were also determined in both of the oils and compared. Reversed-phase high-performance liquid chromatography analysis of triacylglycerol molecular species showed that the pupal oil is rich in molecular species with equivalent carbon numbers (ECN) C36, C40, C42, C44, and C48. There was a significantly higher level (P < 0.001) of trilinolenin (C36) in the oil of tapioca-based silkworm as compared to castor-based silkworm pupae. Regiospecific analysis of the oil showed a higher level of ALA at the sn-2 position of silkworm pupae grown on tapioca (60.2%) as compared to those grown on castor (47.3%) oil. Thus, the presence of a large amount of ALA and their predominance at the sn-2 position make the eri pupal oil highly nutritious, provided that the oxidative stability is ensured.

Lipid Profiles and Oxidative Stability of Silkworm Pupal Oil,

The oil content of the silkworm, Bombyx mori, in the pupal stage was 4.8% for the male and 9.0% for the female (wet basis), respectively. Total lipid (TL) extracted from silkworm pupae mainly consisted of triacylglycerol (TG), phosphatidylethanolamine, and phosphatidylcholine. TL and TG contained approximately 40% α-linolenic acid as the predominant fatty acid. 20:3n-3 was also present in the pupa, but the quantities were very small. Total tocopherol in TL was 125.2 μg/g lipid for the male and 224.1 μg/g lipid for the female, respectively. The oxidative stability of TL was confirmed by measuring the decrease in oxygen in the headspace. The oxidative stability of TL from silkworm pupae was very high and no difference between sexes was appeared. It has been suggested that a synergistic effect between phospholipids and tocopherol in silkworm pupa plays an important role in protecting the lipids against oxidation. Furthermore, the silkworm pupa contained carotenoids such as lutein and neoxanthin. These carotenoids may act as antioxidants in TL. The silkworm pupa would be a good source of the functional fatty acid, α-linolenic acid, and of the functional pigments, lutein and neoxanthin.