There is growing concern about the use of plastic in packaging for food materials, as this results in increased plastic waste materials in the environment. To counter this, alternative sources of packaging materials that are natural and based on eco-friendly materials and proteins have been widely investigated for their potential application in food packaging and other industries of the food sector. Sericin, a silk protein that is usually discarded in large quantities by the sericulture and textile industries during the degumming process of manufacturing silk from silk cocoons, can be explored for its application in food packaging and in other food sectors as a functional food and component of food items. Hence, its repurposing can result in reduced economic costs and environmental waste. Sericin extracted from silk cocoon possesses several useful amino acids, such as aspartic acid, glycine, and serine. Likewise, sericin is strongly hydrophilic, a property that confers effective biological and biocompatible characteristics, including antibacterial, antioxidant, anticancer, and anti-tyrosinase properties. When used in combination with other biomaterials, sericin has proved to be effective in the manufacture of films or coating or packaging materials. In this review, the characteristics of sericin materials and their potential application in food-sector industries are discussed in detail.

Introduction: A number of biological wastes and factory waste materials have been tested recently for the eco-friendly biosynthesis of nanoparticles. Sericin protein (SSP) is usually removed from the silk cocoon during the degumming process in the process of making the silk, and this sericin protein is normally thrown away by the sericulture industries as waste materials. It is found that this sericin protein possesses a number of biological properties. Methods: Considering this, in the present study, an effort has been made to biosynthesize gold nanoparticles (SSP-AuNPs) using the waste sericin solution as the reducing and capping agent and investigate its biopotential in terms of its wound healing, antioxidant and antibacterial activities. Results: The synthesis of SSP-AuNPs was perceived by the visual color change and confirmed by UV-Vis spectroscopy with absorption maxima at 522 nm. Further characterization of SSP-AuNPs was done by TEM, EDS, XRD, FTIR, DLS, zeta potential, TGA, AFM, etc. The size of SSP-AuNPs was found out to be 54.82 nm as per the particle size analyzer and the zeta potential is − 19.8 mV. The SSP-AuNPs displayed promising wound healing potential of 70.96 and 69.76% wound closure rate at 5 and 10 μg/mL respectively as compared to 74.91% by the Centella asiatica taken as a positive control. It also exhibited promising antioxidant potential in terms of the DPPH, ABTS free radical scavenging, reducing power potential, and total antioxidant capacity. Besides, the SSP-AuNPs also displayed significant antibacterial activities against the tested pathogenic bacterial with the diameter of inhibition zones ranging between 12.10 and 14.96 mm as compared to the positive control cephalexin that displayed inhibition zones ranging between 12.08 and 13.24 mm. Discussion: Taken together, SSP-AuNPs could serve as an interesting candidate for food, cosmetics, and biomedical fields in the applications of wound healing, cosmetics, antibacterial bandages, and ointments, etc.

Proteins are some of the most commonly used biomaterials in food technology, especially in food packaging, coatings, and additives. They are outstanding candidates for producing innovative food components due to their immense nutritional properties, molecular characteristics, biocompatibility, biodegradability, and safe status. Numerous application examples of protein-based films and coatings in food packaging also approve their significant role in food packaging materials. Sericin is a natural silk globular protein, which is usually discarded as a biological waste material after removing the fibroin for making silk products from the silk cocoon. In the current investigation, an attempt was made to extract this usually wasted silk protein from the silk cocoon, purify it, and study its potential applications in the food sector as a food packaging material. The sericin was extracted from the silk cocoon by the degumming method. The protein concentration of the extracted crude sericin sample was estimated by the standard Lowry’s method using the bovine serum albumin as the reference standard. Linearity was obtained (R² > 0.99), and the protein concentration of the crude sericin was found out to be 3.60 % (w/v). The purification of the crude protein was carried out by dialysis using a cellulose tubing with a molecular weight cutoff of 12 kDa, followed by freeze-drying. The protein concentration of the purified sericin was found out to be 3.47 % (w/v). Following extraction, sericin can be used as the food packaging material. Proteins, especially sericin, which is a byproduct, can provide a low-cost and naturally occurring raw material to be used as green formulation ingredients in the food industry as a food packaging material. Further research is under process to evaluate the antimicrobial and antioxidant potential of the extracted sericin and study its applications, including food packaging materials.

Many antibacterial agents have been continuously used by various industries in order to extend shelf life by controlling spoilage bacteria and reducing the risk of pathogenic bacteria. However, there are concerns related to safety and various health-related issues. The sericin in silk cocoons is considered as a waste product in the silk industry and is usually thrown away. Sericin is known to possess a number of important biochemical properties. Considering this, in the present study, sericin protein was extracted from silk cocoons via a degumming process, and its antibacterial activity was investigated against a number of foodborne pathogenic bacteria using standard procedures. Its synergistic antibacterial activity was also investigated using both sericin protein and standard antibiotics such as ampicillin, azithromycin, cephalexin, erythromycin, gentamycin, kanamycin, and streptomycin. The results showed that sericin extract displayed a prominent antibacterial effect against all the tested foodborne pathogenic bacteria, with the diameter of inhibition zones ranging from 9.44 ± 0.04 mm to 12.09 ± 0.58 mm, and the results were comparable with those of the standard antibiotics. The sericin extract at 500 µg/disc displayed the highest inhibition zones against both the tested E. coli (12.09 ± 0.58 mm) and the L. monocytogenes (11.51 ± 0.35 mm). Furthermore, sericin along with the standard antibiotics at (25 µg + 5 µg respectively)/disk displayed significant antibacterial potential against all the tested foodborne pathogenic bacteria, with the highest inhibition zone against Salmonella Typhimurium (26.59 ± 0.74 mm). The minimum inhibitory concentration and the minimum bactericidal concentration values of the sericin extract ranged from 0.0625 to 1.0 mg/mL. These data suggested that sericin extract has promising antibacterial potential that can be utilized in various industries as an effective antibacterial agent.