Renewable Resources in Films and Coatings Technologies: Part I: Polysaccharides – Gums and Starch

Dear Colleagues,

Coating processes are used in many industrial applications, and polysaccharides/carbohydrates derived from renewable sources such as gums and starches are attracting interest for film/coating applications.

Gums are categorized into three groups: seaweed-based gums, plant-origin gums, and microbial gums. Seaweeds are natural sources of industrial gums such as agar, carrageenan, furcelleran, and alginic acid (alginate). Plant-origin gums produced commercially mainly include Arabic gum, karaya gum, ghatti gum, mastic gum (“Chios mastic” and “Pistacia lentiscus”), neem gum, locust bean gum/carob gum, Joel or Jingan gum, Mesquite gum, etc. Recently, microbial gums such as gellan, xanthan, pullulan, bacterial cellulose, and curdlan have been introduced as novel functional components of edible coatings and packaging. Cellulose is produced by bacteria as well as plants and other organisms.

Starch is found in plants, and it has a complex structure. Traditional starch products have faced stiff competition from alternatives, including synthetic products, but interest in them has not waned because of their renewable nature. 

These types of polysaccharides can be extruded into biodegradable, edible, renewable, and low-cost films and coatings, alone or in combination with bioactive compounds, as supplements or substitutes of conventional materials. They have considerable properties which are suitable for various food, pharmacy, and medicine applications.

The coating method applied is determined by the properties of the active substances and the solid that requires coating, as well as the intended product quality. The most commonly used methods include dipping, brushing, or spraying the product and creating standalone film from solution or through thermoformation (rarely used). Drum coating (sugar coating or film coating) and fluidized bed spray coating (spray coating: top spray, tangential spray, bottom spray (Wurster process) or rotor process) are the oldest coating methods.

Protection, taste masking, and the delivery and controlled release of an active substance are some of the achievements of coating processes. In term of protection, a semipermeable barrier on the surface is produced aiming to reduce respiration rate, weight loss, and maintain the nutritional value. Edible protective layers have recently attracted attention for their potential to replace plastic packaging. 

Ingredients or substances are coated in order to protect components from external influences or interactions with other ingredients. A frequently used application of such protective layers is the prevention of moisture migration. This can occur between components of the same matrix due to different water activities. Hygroscopic substances absorb moisture from the environment, which usually has a negative impact on the quality of the final product.

The protective layer is completely odorless, tasteless, and colorless and cannot be perceived by the consumer, while at the same time, it can extend the shelf life of the product and minimize the gas exchange between product and environment.

The aim of the present Special Issue is to present recent advancements in this field through research and review papers.

It is our pleasure to invite you to submit a manuscript to this Special Issue. In particular, the topics of interest include but are not limited to the following:

• Polysaccharide gum-based edible film and coating applications;
• Starch-based edible film and coating applications;
• Coating and delivery of flavor, active ingredients, food additives, and antimicrobials using edible films and coatings;
• Applied systems to produce optimal edible films and coatings;
• Coating non-fluidizable particles such as tablets, capsules, etc.;
• Coating of whole foods (e.g., fruits);
• Increasing particles’ functionality to mask odors or tastes or to release specific active substances;
• Microcapsules (also called coatings) and microbeadlets consisting of an outer shell (the coating material) that encloses a core.

Dr. Monica Trif
Dr. Alexandru Rusu
Dr. Sneh Punia
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• seaweed-based gums
• plant-origin gums
• microbial gums
• starch and starch derivative
• film coating
• edible films and coatings
• microcapsules
• coating ingredients
• tablet and capsule coating
• control release and delivery
• spray coating
• drum coating