Nutritional Value, Food Ingredients, Chemical and Species Composition of Edible Insects in China Nutritional Value, Food Ingredients, Chemical and Species Composition of Edible Insects in China

As the prevailing food cultures, edible insects could be dated back to ancient China. It is becoming clear that insect resource can be mass‐produced in sustainable development food utilization. China could introduce insects into modern western diets. It is a precious resource considering the nutritional value, food ingredients and chemical composition of species. Meanwhile, the edible insects’ consumption also led to a challenge of address‐ ing food security, nature conservation and the erosion of traditional food culture. We summarized the resourceful edible insects containing the nutrition substance, such as essential proteins, amino acids, fatty acids, carbohydrates, vitamins, mineral elements and other functional ingredients with the insect secondary metabolite, including the flavonoids, alkaloids, polysaccharides, hormones and phospholipids, which have high economic value for development and utilization.Based on the history, custom, plasmid resource, production and status of edible insects in China at present, it has been proven that the development of insects food well matches the need for human health in China.


Discussing edible insect's resources value
Insects are most species-rich resources and one of the largest biological groups in earth organisms. With its wide resources, speed of reproductive growth, lower feed cost, edible insects are an important food source which has immense potential of the development and utilization. The edible insects contain the reasonable structure of nutrition, high nutritional value and numerous

Development and utilization of edible insects resource
Edible insects can be divided into food insect, drug/medicinal insects and drug dual-use insects, etc., based on the different insects eaten resources classification. Edible insects are directly for a daily food consumption and the insect has important nutritional value to human to be developed and utilized. The U.N.'s Food and Agriculture Organization (FAO) has released a report in 2013 called Edible Insects: Future Prospects for Food and Feed Security [6]. It outlines the many benefits of eating insects-for human in the entire world. As early as 1980, it was put forward to supplement the human food shortage in the Fifth Latin American congress of Dietitians and Nutritionists, which should regard them that as part of food source insects as human food in many countries has been increasingly apparent at present.
Scientists have found that some insect protein from the red ants, grasshoppers and some of predaceous diving beetle (Dytiscidae)are enough to compete with lean beef.
The protein of adult insect content is rich, significantly higher than that of pork, beef, chicken, fish and eggs. Experts predict that insects will be the third category only after cell raw material and microbial protein sources in future [7]. As in poor regions, people need essential nutrients to provide, the services of the services of insect and spider equally good. And as in developed country like the USA, the insect and spider are the higher protein food from a healthy choice. Insects are a highly nutritious and healthy food source with high fat, protein, vitamin, fiber and mineral content [6]. "Gathering and farming insects can offer employment and cash income either at the household level or in larger industrial-scale operations." It could offer work to millions of people around the world. Besides, there is evidence that most of breeding insects produced the harmful greenhouse gases to the environment that may be less than those of livestock [8]. This result will help to decrease the cost of food production, reduce emissions from greenhouse gas. In recent years, along with the progress of modern science and technology, the process technology of the functional food and health-food markets of edible insects accelerates unprecedentedly in China. For example, concentrated insect protein oral liquid specialized in honey, royal jelly, pollen and propolis, the traditional shellac ash, etc. Insect oils of some are mainly used as the functional fat-soluble ingredients.
As mentioned above, insects are the largest species and biological organisms on earth. And their resources arre extremely rich. Moreover, its nutrition structure is reasonable with high nutritional value and many functional constituent; insects thus will be considered as an important food source for the development and utilization with huge potentials. Combined with the existing research results and their advantages of high reproductive growth speed and low feed cost, large-scale production provides a reliable technical support. The development and utilization of edible insect resources thus has a very broad prospect.

The value of nutrition and health benefits of edible insects
According to the records, about 3650 species of the edible insects have been found and used [8]. The advantages of edible insects in the food development, one highlights show, at the beginning of competing namely, already competed from widely distributed, best variety, fast reproduction, high nutritional value, breeding easy and high food conversion rate indistinct development competes for the sustainability in ecosystems and biodiversity. They thus have become an additional source of food with high nutritional value containing rich protein. At the same time, the insects' food has low fat and low cholesterol with a reasonable structure (less fleshy fiber) easily absorbed, and abundant trace elements, etc. It is, therefore, better than that of meat and eggs [9].
The results of research showed that edible insect contains various nutrient elements, such as protein, amino acids, fat, fatty acid, vitamins and mineral elements.

Edible insect protein
Onincx said "It proves the hypothesis that insects can be a more efficient source of protein, and I definitely believe there is a future for edible insects" [10]. Studies have shown that protein content is not the same for the different insect states. The protein content of adults is the highest, pupa is at second and larvae at the lowest. For wasps, the adult has 71.07%, pupa has 58.59% and a larva has 50.83% of protein content, according to the protein calculations of insects at different ages.
The protein content of different subjects' insect is not the same either. The Orthoptera is higher than Homoptera, higher than Odonata, Diptera, Hymenoptera, Hemipter, Lepidoptera and then Coleoptera insect [11].
Amino acid is the basic functional unit for biological macromolecular protein, and is also an important part of food constituted as insects' nutrition. The amino acid content of edible insects is 10-70%, and essential amino acid content is 10-30%. Most of the amino acid ratios for insect are appropriate and have approached or even exceeded that of the WHO/FAO required ratio. Study also revealed that the existence of large amount of free amino acids associated with insect freshness [6,12]. The content of free amino acid of edible insects in the blood is about 3000-23400 mg/kg that is higher than any other higher animals of the universe.

Carbohydrate of edible insects
In addition to glucose, triose, glycogen, erythritol, ketose sugar, fructose and ketoheptose, edible insects' carbohydrates (sugars) sort are very rich and the sea algae sugar (insects' ingredient blood sugar) content is the same. Edible insects are easy to digest and absorb carbohydrates, and total sugar containing amount is generally as low as 1-10% or even lower [13]. For example, the total sugar content of Cyclopelta parva is 1.45%, and that of Tessaratoma papillosa is 0.15% [14].
Chitin is also the main material of edible insects' skin and bones. Its chemical name is N-acetyl-D-glucosamine copolymer with the function of adsorption abilities for a specific toxin. then, It is also a low calorie food that it has the very high nutrition value for the good for the health care. Chitin promotes intestinal peristalsis, fine regulating intestinal bacteria, reduce weight due to fat, anti-aging, enhance the immune function and assist in preventive treatment of high blood pressure, etc. Chitin is usually between 15 and 18%, rich in edible insect body. However, at different insect states, chitin content is different, such as the chitin content of dry silkworm pupa is 3.73% and Skim pupa's content reached 5.55% [3].

Mineral elements and vitamin of edible insects
Edible insects are rich in mineral elements, including Ca, P, Fe and zinc, etc., which are often needed as the supplement of human body. It is reported that feed insects can fulfill the requirement of animals' Fe, Cu, Zn and Mg mineral elements [15]. The locusts contain 27 kinds of mineral elements, notably Mn, Fe, Cu and Zn [16]. Many ants are rich in Zn, Se, Mn and Mg, etc. The level of Zn is two times more than pork liver, and eight times higher than soybean [17].

Lipid substances of edible insects
Insects are rich in oil and lipids. The fat content of pupae and larvae is higher than the adult insect. Report shows a decline in fat content after feather state of the insect. Fat content is commonly between 10 and 50% for edible insects. A recent study has found the fat content of wasp. In larvae, the fat content is 29.01%, while in pupae, it is 27.25% and in adults, it is for 17.22% [10]. Unsaturated fatty acid and palmitic acid are higher in edible insects. Among them, linolenic acid content is higher in Lepidoptera, and the oil acid content is higher in Coleoptera.
Related research also proved the variation in fat content for different species of insects. It is revealed that the fat content of Coleoptera is higher than that of Lepidoptera, Half wings, Hymenoptera, Odonata, Diptera and Orthoptera [19]. In fact, natural insect wax also contains a small amount of senior fatty acids. They can be used as pharmaceutical raw materials such as textile and stencil making model. Based on the infrared spectra analysis of insect wax, it was suggested that insect's wax is composed of mainly long-chain hydrocarbons, fatty alcohols, fatty acids and some compounds with aromatic rings mixture.

The nutritional evaluation of insect oil/fat
Insect oils (fat) are a kind of nutrient substances with several physiological and biological activities and functions. It has a high value of research, development and utilization no matter whatever be the quantity or quality. Fat content of insects' body changes with its life cycle, meanwhile it is closely related to the growing up of the insect species [20].

The oils and fats content in insects' body
Many studies have also displayed that the fat content of insects differed in the same species.
The pupa and larva's oils (fat) were higher than adults' in the same species. And, during the winter period, the insects' oil contents were higher. The fat content of insects' dry body was commonly 10%, while many other insects have fat content of 30%, or even up to 77.16% ( Table 2).

Fatty acid composition of insect oils and fats
Insects are rich in fat and their fatty acid composition is reasonable. The saturated fatty acids and unsaturated fatty acid ratio of edible insect is generally less than 0.4. Its partial fatty acid composition ratio is close to the fatty acid composition of fish proportion, and thus can be used as a natural health care product. The saturated fatty acids (SFA) of insects is mostly composed of the palmitic acid (C16:0) but not stearic acid (C18:0) which is relatively high in vertebrates.
In addition, insect oil has the odd number carbon fatty acids rarely existing as the pentadecanoic acid and heptadecanoic acid that are relatively rare in the nature but extremely common in insects. As shown in Table 2, the heptadecanoic acid content of termites' adult, the housefly larvae and housefly adults were all above 2%. As odd number carbon fatty acid has special raw active function, it was found that they have stronger antitumor activity. Therefore, many researchers are very interested in insects' enrichment and separation of odd number carbon fatty acids, leading a hotspot in the research of the insect oil.
The insect oil is a solvent of natural active products containing the lecithin and fat-soluble D raw element (such as vitamin A, D, E). These active natural products have a strong physiological and biological function with the extremely important value.

The nutrition evaluation of insect oils
The fatty acid of insect oil and fats predominantly composes of unsaturated fatty acid and its proportion could be more than 60%, and can even reach up to 80% in some insects. The fatty acid of insect oil and fats predominantly composes of unsaturated fatty acid. And, its proportion could be more than 60%, and can even reach up to 80% in some insects. The fatty acid composition of some of the insects' oil and fats is shown in Table 3.
Among the unsaturated fatty acids (USFA) and monounsaturated fatty acids (MUFA) of insects, many oleic acid (C18:1) is a unique composition with the proportion at about 30 ± 10% or more. This is much close to fish food and better than poultry meat and eggs [5,18,20]. It is good for the health of human body. The bioactive mechanism of insects' fatty acid has been studied in the body and has proven the exact functional fatty acids physiological activity. It pointed out that the high linoleic acid content in certain insects has a close relationship with its strong reproductive functions. Research indicated that stearic acid could neutralize the nutritional effects, and the lauric acid (C12:0) and nutmeg acid (C14:0) can lead to the elevated level of the fatty acid of cholesterol. These kinds of saturated fatty acids (SFA) are low in insect oil.
Nutritionists believe that general proportion between the n-3 and n-6 (PUFA) should be based on the breast for 1:3-10 [21]. According to the best food and nutritional science, linoleic acid and linolenic acid are the essential fatty acids (EFA). These two kinds of fatty acids are obtained only from food directly. In case EFA is lacking, the oil should be restricted to oil's fatty acid with the low biological titer, and nutritional value is thus low. It can directly cause the growth retardation, reproductive barriers, skin damage (such as a skin rash), liver, kidney, nerve and visual diseases. The over-taken polyunsaturated fatty acids (PUSFA) can cause chronic hazards. Therefore, the world health organization (WHO) recommended a standard of food oil in adults, the recommended dietary fatty acids taken (1990) are produced by the percentage of the total energy, energy and food: fat 15-30%, of them SFA < 10, PUFA 3-7 [21].
In a word, insects have the characters of quick propagation, high content of fat composed of reasonable composition of fatty acids. They are thus a good edible oil resource with high quality.

The secondary metabolites of edible insects and potential medicinal substances
It has been proved by a large number of studies in recent years that the insect secondary metabolite is important sources to find new leading compounds. Arthropod natural products with insect constituent are structurally diverse, including compounds derived from fatty acid, polyketide, terpenoid, nucleoside and amino acid pathways. However, the biosynthesis of most of these compounds has not been studied in detail (Figure 1) [22]. Historically, traditional use of plants as medicines, known as "ethnobotany", has been extensively recognized and studied. It is worth noting that insects have been utilized as medicines in diverse cultures, especially in traditional Chinese medicines. It may be valuable for the development of the useful drugs. Another ongoing investigation by our group was the searching of new antibacterial structure from insects' natural products. More modern studies designed to determine the medicinal properties of isolated chemical components from insects and other arthropods will be performed.  (7), grasshoppers (9), and beetles (2,8,11,12).

Edible insects in China
According to the results of the survey, edible insect resources have been reported for more than 283 species with subspecies, involving 13 orders, 71 families in China [23]. Among them, the Orthoptera, Hemiptera, Coleoptera, Lepidoptera and Hymenoptera account for the majority number. Though most of the species have not been reported, the quantity of edible species identified is still growing. For this purpose, the author studied more than 283 species and subspecies of the edible insects in China. We recorded them as follows with * marked for the firsttime report. China's edible insect species and their edible insects were discussed as follows:

Ephemerida
The order includes two families of the larva of Ephemerellidae and Ephemerella jinghongensis Xu et al.

Odonata
The order includes four families of Aeshnidae, Gomphidae, Libellulidae and Lestidae.

Blattodea
The order includes two families of Blattidae and Corydiidae.

Insectivorous culture as sustainable development of food in China
China has a long insectivorous culture and important insect food resources. The characteristics of insect diversity and high nutritional value promise the great potentials to utilize these precious resources. At present, the development and utilization of China's edible insects are mainly in two aspects: the insect dishes and insect protein products.

Insect dishes in China quickens your appetite
Chinese insect dishes and foods often include traditional and innovative ways of two eating, such as oil silkworm chrysalis, Cicada Fried Crispy Fried locust Lang, Chinese caterpillar fungus duck and Tremella silkworm chrysalis, etc. Also, the insects could be used as ingredients for bread, insect drinks and wine. Edible insects can also be processed into insect nutrients liquid and health products as the main raw materials that are currently fashionable gifts to share for human health. And, most of this kind of products in China are listed as follows: The proteolytic enzyme of honeybee pupa and Bee pupa drinking; Royal Jelly Capsules, Royal jelly cream and Royal jelly powder; Drone pupa wine, Gekko-drone wine which is prepared with Gekko, drone pupa, Lycium chinense and rice wine and through twice soaking. Tussah pupa protein drink for quick nutrition supplement; Amino acid drink of yellow powder insect caterpillar protein; Amino acid drink of sweet potato hawkmoth canned; Soy sauce of silkworm chrysalis; Dry bread cake of silkworm chrysalis protein; Silk protein beverage and jelly, silkworm moth oil and wine, etc. In addition, the raw materials of nutritional health products used more ants as well, which will satisfy the demands of treating different diseases like tracheitis, active chronic gastritis, dysmenorrhea, psychoneurosis, pulmonary tuberculosis, alopeci and impotence, etc.

The development of insect protein products in China
The fly pupae are mainly used as raw material to develop traditional curative food and make the high protein food through processing. These research works currently focus on the development and utilization of several kinds of insects: flies, locust, cicadas and silkworms and so on. Then, this kind of eating insects is rich in protein, which can be compared to other foods such as meat and eggs. They can, not only solve the food shortage, but also food crisis of global food inequality in the near future.
Extensive and profound Chinese food culture is glamorous. The miracle of insectivorous culture refers to a gorgeous art of diet culture treasure in China. At once, as one of the most urgent tasks in the development and utilization of insects, edible insects can be converted to a steady stream of elegant food dedicated to all humanity.

Author details
Weiping Yin*, Junna Liu, Huaqing Liu and Biyu Lv *Address all correspondence to: yinwp@haust.edu.cn School of Chemical Engineering and Pharmaceutics, Henan University of Science and Technology, Luoyang, PR China