Sustainable Uses of Byproducts from Silk Processing

Narendra Reddy, Pornanong Aramwit

• Publisher: Wiley-VCH
• Year: 2021
• ISBN:
  9783527828746
• Edition: 1
• Topic: Sciences physiques
• Subtopic: Chimie industrielle et technique

Sustainable Uses of Byproducts from Silk Processing

Explore this authoritative guide to transforming the silk industry written by two experts in biopolymers and materials science

Sustainable Uses of Byproducts from Silk Processing delivers a detailed treatment of the properties and potential applications of silk sources, by-products, and waste. The book describes the composition, structure, processability, and potential applications of all of the different kinds of silk by-products. Highly relevant to those working in mulberry cultivation, silkworm rearing, and silk processing, the distinguished authors offer information on how to transform silk by-products into new materials, energy, fuel, fibers, composites, food, cosmetics, and feed.

Using a valorisation approach to the silk protein sericin and its by-products and taking an application-oriented view of materials sources and wastes in the silk industry. Implementation of these techniques promises to further industries as diverse as cancer treatment, pharmaceuticals, nutraceuticals, and environmental cleanup.

Readers will also benefit from the inclusion of:

• A thorough introduction to sericin, including its structure and properties, how to process it, and its various applications
• An exploration of mulberry leaves, stems, and fruits, including their composition and properties, processing, and non-feed applications
• Discussions of the various uses of silkworm pupae, including food and feed, pupae oil properties and applications, biodiesel, byproducts of biodiesel, and the extraction of chitin and proteins from the pupae shell
• An examination of the applications of silkworm litter

Perfect for protein chemists, biotechnologists, cosmetics industry professionals, and materials scientists, Sustainable Uses of Byproducts from Silk Processing will also earn a place in the libraries of polymer and cosmetic chemists who seek a one-stop reference for current and emerging sustainability practices in the silk industry.

1
Sericin: Structure and Properties

1.1 Type of Silk Sericin

Sericin is a natural product from the silkworm. Sericin is one of the major protein components in the cocoons of Lepidopteron insects. Sericin is a glue‐like coating protein surrounded with filament protein, fibroin (Figure 1.1). In manufacturing silk, sericin is a waste product from the degumming process. The silk sericin is classified into two types based on the feeding source of the silkworms: mulberry and non‐mulberry sericin. The mulberry silkworm, Bombyx mori, is a well‐known source of commercial silk production. This worm is a completely domesticated species that feeds on mulberry leaves. B. mori had long been developed for an indoor cultivation for the silk industry, whereas non‐mulberry silkworm or wild silkworm is the group that feeds on other leaves such as oak leaves and castor oil leaves. Most of the non‐mulberry silkworms cannot be reared indoors for their whole life cycles. The well‐known non‐mulberry silkworms are Antheraea, Samia ricini (or Philosamia ricini), and Cricula trifenestrata. Antheraea is a genus of silkworm that feeds on oak leaves and produces “tasar” silk, such as Antheraea assamensis (producing muka silk), Antheraea mylitta, Antheraea pernyi, and Antheraea yamamai. S. ricini produces the famous “eri” silk. In the wild environment, S. ricini feeds on castor oil plant leaves. C. trifenestrata is a wild silkworm producing “cricula” silk. The diversity of silkworm sources (genus, species, and diet) may produce distinct sericin characteristics.

1.2 Localization of Silk Sericin

Sericin is located at several sites of silkworms and cocoons. In the mulberry silkworm, B. mori, it has been reported that sericin is present in three components including silk gland, cocoon, and floss (Gamo et al. 1977; Kikkawa 1953; Yamada 1978). For non‐mulberry silkworms, sericin is also secreted in the cocoon peduncle (Dash et al. 2006). The silk gland is the site that produces sericin. In a histological study, sericin was found to be mainly synthesized in the middle and posterior of the silk gland. Sericin protein is then sent to anterior silk glands via the lumen for secretion and cocoon construction (Consortium 2008; Kikkawa 1953; Yamanouchi 1922).

Figure 1.1 Scanning electron microscope (SEM) of a silk filament that contains fibroin and sericin.

1.3 Molecular Mass of Sericin

The molecular mass of sericin has been observed using sodium dodecyl sulfate and polyacrylamide gel electrophoresis (SDS‐PAGE). The diversity pattern of sericin was investigated from various extraction sites, extraction methods, species, and strains. Figure 1.2 shows the molecular mass of sericin from different extraction methods using SDS‐PAGE.

1.3.1 Middle Silk Gland Sericin

The middle silk gland (MSG, Figure 1.3) is a synthesis site for sericin in silkworm. Sericin obtained from MSG is known as native sericin. The MSG sericin measured by gel electrophoresis was found in inta...