Research progress on the nutrition and active ingredients of silkworm pupae and their applications
January 29, 2024
Silkworm farming is one of the earliest agricultural activities in China, with the saying "Fuxi turned silkworms" and "Leizu started silkworms" in ancient times. Silkworms have also become one of the most important economic insects in ancient China.
Silk and pupae are both the main economic values of silkworms. Silk, as a textile raw material, was used very early in China. Silk produced from silk is one of the important characteristics of Chinese civilization. The Silk Road has also become an economic corridor connecting ancient China with Asia, Europe, and Africa; The development and utilization of silkworm pupa is much later than that of silk, and its utilization level is not high. In the early stage, the focus was mainly on the development of edible properties.
China has the world's largest silkworm production, with a considerable number of silkworm pupae. If the nutrients and active ingredients in silkworm pupae can be fully developed and utilized, and silkworm pupae resources can be widely utilized on this basis, it can not only save resources and turn waste into treasure, but also increase the added value of silkworms and extend the industry chain, thereby achieving high-quality development and significant economic benefits of the silkworm industry.
01Nutrient and active ingredient composition in silkworm pupae
1.1 Nutrient composition of silkworm pupae
The human body needs to obtain nutrients from food, mainly including protein, fat, vitamins, etc. Silkworm pupae contain abundant nutrients. Bai Hao et al. detected that the crude protein content of silkworm pupae was 65.5%, crude fat content was 23.8%, and total sugar content was 1.2%. Other studies have shown that silkworm pupae also contain minerals such as Ca, P, Fe, as well as vitamins, hormones, and other components.
The protein content of silkworm pupae accounts for more than 50% of the dry weight content, and the protein structure and composition of silkworm pupae are similar to human protein, which is easily absorbed by the human body, with an absorption rate of over 90%.
The protein of silkworm pupae is composed of 18 amino acids. Liang Guiqiu et al. studied four different varieties of silkworm pupae and found that their amino acid content varies. However, the proportion of glutamic acid, aspartic acid, glycine, valine, leucine, alanine, arginine, lysine, and arginine to the total amino acid content is not significantly different, and the proportion is very high, The nutritional ratio of 8 essential amino acids for the human body meets the requirements of FAO/WHO (Food and Agriculture Organization of the United Nations and World Health Organization). Silkworm pupa oil accounts for 25-30% of the dry weight, with unsaturated fatty acids accounting for over 70% of the total silkworm pupa oil.
By comparing the nutritional content of silkworm pupae with several commonly used foods in Table 1, it can be seen that silkworm pupae are not only rich in protein, fat, iron, calcium, magnesium, and vitamin B2, but also have high levels of potassium, selenium, vitamin B1, niacin, and other nutrients.
1.2 Active ingredients of silkworm pupae
Bioactive substances are compounds in animals and plants that have biological activity and can cause various biological effects after interacting with the body, including sugars, lipids, protein peptides, sterols, alkaloids, glycosides, volatile oils, and other substances. Silkworms effectively enrich their active ingredients by consuming mulberry leaves, and during their metamorphosis and development, they effectively preserve their active ingredients in their pupae, making them rich in highly active substances.
The amount of chitin that can be extracted from silkworm pupae is over 50%, while the amount of chitin that can be extracted from crabs is only 20-25%. The useful chitin in silkworm pupae is twice that of crabs. In Jin Chao's research, it was found that the DNJ content in the 5th instar larvae of 70 silkworm varieties ranged from 0.03% to 0.39%, the total flavonoid content ranged from 0.38% to 1.40%, and the total alkaloid content ranged from 0.87% to 1.55%. In addition, silkworm pupae also contain active ingredients such as phospholipids, polysaccharides, ergosterol, adrenaline, adenine, hypoxanthine, choline, and various protein hormones.
02Research progress on the application of nutrients and active substances in silkworm pupae
2.1 Application Research in the Food Industry Silkworm pupae have great utilization value in the food industry. One is to directly use it as food, through cooking such as stir frying, steaming, and deep frying, and fully heating it until cooked before consumption. It is a nutritious and delicious food.
Secondly, it can be used as a food additive. Due to its selective permeation effect on O2, CO2, and C2H4, chitosan can be used as a food preservative and preservative.
Thirdly, it is used as a weight loss food. The fatty acids in silkworm pupae are mostly unsaturated fatty acids, among which α- Linoleic acid has the effects of lowering blood lipids, clearing free radicals in the body, and antioxidation, making it a highly promising new type of fat source.
Fourthly, as a health food (functional food), Mu Lixia et al. have studied that the enzymatic hydrolysis products of silkworm pupa protein (SPP) have a strong inhibitory effect on the in vitro proliferation of tumor cells MGC-803. Alkaloids have anti-tumor, anticancer, hypoglycemic and other effects, while DNJ has insulin sensitization and improved insulin resistance.
2.2 Application research in medicine
Silkworm pupae not only have high edible value, but also have high value in medicine. The Compendium of Materia Medica and the Compendium of Materia Medica both have corresponding records on the medical effects of silkworm pupae, respectively stating that they "treat infantile malnutrition, elongate muscles, reduce fever, eliminate roundworms" and "harmonize the spleen and stomach, dispel wind and dampness, and enhance yang qi".
The silkworm pupa protein peptide extracted by modern genetic engineering and enzymolysis technology has a good role in the prevention and treatment of diabetes, arteriosclerosis, hypertension, cirrhosis and coronary heart disease, and can be used to treat leukopenia, acute and chronic, toxic hepatitis, physiological decline and other diseases.
Chitosan can produce red blood cell adhesion by cross-linking with the surface of red blood cells, or undergo some kind of re aggregation reaction in the blood, causing red blood cell aggregation to achieve the purpose of hemostasis, thus being used as a hemostatic agent.
DNJ shows high efficiency in inhibiting the activity of intestinal glycosidase, and has a significant effect in the treatment of type II diabetes. Arginine has significant therapeutic effects on leukopenia, chronic hepatitis, cardiovascular and cerebrovascular diseases, and malnutrition. It is also due to its important role as a raw material for male sperm protein in improving sexual function. In addition, silkworm pupae have inhibitory effects on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. The abundant chitin in silkworm pupae can enhance the body's immune system, strengthen the liver, and other functions.
