Review Articles

Currently, food waste is a major concern for companies, governments, and consumers. One of the largest sources of food waste occurs during industrial processing, where substantial by-products are generated. Fruit processing creates a lot of these by-products, from undesirable or “ugly fruit,” to the skins, seeds, and fleshy parts of the fruits. These by-products compose up to 30% of the initial mass of fruit processed. Millions of tons of fruit wastes are generated globally from spoilage and industrial by-products, so it is essential to find alternative uses for fruit wastes to increase their value. This goal can be accomplished by processing fruit waste into fillers and incorporating them into polymeric materials. This review summarizes recent developments in technologies to incorporate fruit wastes from sources such as grape, apple, olive, banana, coconut, pineapple, and others into polymer matrices to create green composites or films. Various surface treatments of biofillers/fibers are also discussed; these treatments increase the adhesion and applicability of the fillers with various bioplastics. Lastly, a comprehensive review of sustainable and biodegradable biocomposites is presented.

This review examines the roles of different natural polymers, composites, and nanoengineered materials that have been studied in the last 10 years for their use in water treatment. As water quality is a global concern, the use of natural and sustainable materials is fundamental to obtain high value products that can remediate water systems without generating other pollution sources or require extra energy inputs or high side costs. Filtration systems often can provide an ideal alternative to conventional water treatment. Herein the attention is focused on polysaccharides, as these can be easily obtained from green processes and can be sourced from what nowadays are considered as agricultural waste. The inherent variety of functional groups that they have provides a better interaction with certain types of pollutants. Thus, biomaterials have been harnessed to generate filtration systems and other water treatment options.

Timber structures in marine applications are often exposed to severe degradation conditions caused by mechanical loads and wood-degrading organisms. This paper presents the use of timber in marine environments in Europe from a wood protection perspective. It discusses the use of wood in coastline protection and archeological marine wood, reviews the marine borer taxa in European waters, and gives an overview of potential solutions for protection of timber in marine environments. Information was compiled from the most relevant literature sources with an emphasis on new wood protection methods; the need for research and potential solutions are discussed. Traditionally, timber has been extensively utilized in a variety of marine applications. Although there is a strong need for developing new protection systems for timber in marine applications, the research in this field has been scarce for many years. New attempts to protect timber used in marine environments in Europe have mainly focused on wood modification and the use of mechanical barriers to prevent colonization of marine wood borers. The importance of understanding the mechanisms of settlement, migration, boring, and digestion of the degrading organisms is key for developing effective systems for protecting timber in marine environments.

A cost-effective, eco-friendly, and health-promoting packaging system that prevents the passage of greases and oils would fulfill an urgent need. This review discusses what is known about the highly divergent technological paths that have been studied to achieve these objectives. Before the emergence of plastic films, the paper industry addressed these objectives in two ways, by parchmentizing and by high levels of refining of the fibers. Parchmentizing means passing the paper through a bath of concentrated sulfuric acid, followed by rinsing out the acid and drying the sheet. Though both parchmentized paper and highly refined greaseproof paper products are still made, they have been substantially displaced by oil-repellent fluorocarbon treatments of paper. The fluorocarbon treatments have allowed papermakers to achieve greaseproof properties with ordinary paper machine equipment at ordinary refining levels and without a need to immerse the paper in strong acid. Now, however, due to environmental concerns and regulations, the paper industry needs more options. Some promising directions in published research include advances in chemistry, superoleophobic surfaces, nanocellulose films, and systems to protect nanocellulose films from the effects of moisture.

α-Amylases (E.C 3.2.1.1) hydrolyse starch into smaller moieties such as maltose and glucose by breaking α-1,4-glycosidic linkages. The application of α-amylases in various industries has made the large-scale productions of these enzymes crucial. Thermostable α-amylase that catalyses starch degradation at the temperatures higher than 50 °C is favourable in harsh industrial applications. Due to ease in genetic manipulation and bulk production, this enzyme is most preferably produced by microorganisms. Bacillus sp. and Escherichia coli are commonly used microbial expression hosts for α-amylases (30 to 205 kDa in molecular weight). These amylases can be purified using ultrafiltration, salt precipitation, dialysis, and column chromatography. Recently, affinity column chromatography has shown the most promising result where the recovery rate was 38 to 60% and purification up to 13.2-fold. Microbial thermostable α-amylases have the optimum temperature and pH ranging from 50 °C to 100 °C and 5.0 to 10.5, respectively. These enzymes have high specificity towards potato starch, wheat starch, amylose, and amylopectin. EDTA (1 mM) gave the highest inhibitory effect (79%), but Ca2+ (5 mM) was the most effective co-factor with 155%. This review provides insight regarding thermostable α-amylases obtained from microbial sources for industrial applications.

This review article considers published evidence regarding effects of particle size on mechanical properties of plastic matrix materials filled with cellulose-based reinforcements. Cellulosic or wood-based reinforcements in plastic matrices can contribute to higher modulus, lower density, and less tendency to sag in comparison with the matrix phase by itself, while still allowing the resulting material to be cut or milled. Although cellulosic materials are generally too hydrophilic to adhere well to common thermoplastic materials such as polyethylene, such deficiencies can be overcome by use of compatibilizers, e.g. polyethylene-maleic anhydride. Recently many researchers have evaluated nanocellulose in plastic composites. The higher surface areas of nanocellulose generally imply a higher cost of compatibilizer to achieve good interfacial adhesion. This review first examines results of a large number of studies all involving high-density polyethylene as the matrix. Then, to get a more detailed mechanistic view, studies are considered that compare different particle sizes of cellulose-based reinforcements within the same conditions of preparation of composites prepared with various matrix polymers. To summarize the findings, there does not appear to be any consistent and dependable advantage of using nano-sized cellulosic reinforcements when trying to achieve higher values of composite strength or modulus.

The aim of this review is to examine the problems encountered with logs kept in depots and the measures recommended to correct them. Biotic, abiotic, and other factors can affect the quality and quantitative properties of stored logs. Biotic factors include fungi (decay/rot fungi, stain fungi, and mold), insects (wood, bark, and ambrosia beetles), and bacteria. The climatic conditions of ultraviolet (UV) light, wind, and temperature at the storage site can be considered as abiotic factors. In addition, storage problems may be caused by business management, inadequate training and qualifications of depot personnel, and the type of depot floor/ground. Measures to counteract these factors were examined in detail, as a result of field observations and literature studies. The solutions presented included: shortening the storage period and expanding winter production rather than maintaining year-round storage, bringing production planning in line with the needs of the sector and providing sufficient training to workers and technical personnel, as well as increasing the sale of standing trees, separating earlier- and later-felled products in depot areas, installing pheromone traps, and ensuring proper drainage and maintenance of depot grounds. Additional measures to be taken in factory warehouses included water sprinkling and holding logs in water (ponding).

The Chinese national standard for paper ash measurement cannot meet the requirements for accurate and rapid ash measurement in actual production and scientific research because of the long measuring time, tedious procedures, and large human error. This paper reviews some worldwide devices and methods for rapid measurement of paper ash, including ceramic fiber muffle furnace, microwave muffle furnace, the addition of ash adjuvant, dry samples method, direct combustion of paper samples, oxygen-enriched combustion method, chemical analysis method, and ray method, etc. The differences and relationships are identified among these devices and methods. By comparing the different ash measurement methods, the rapid ash analyzer based on X-ray technology has the obvious advantages of short measuring time and small error. Lastly, the present situation and the development potential of these devices and methods are discussed in this review.

Biomass is a class of abundant renewable resource. Its efficient use in the field of biobased materials is one of the important ways for implementation of sustainable development strategies. 2,5-Furandicarboxylic acid (FDCA) as a potential alternative of terephthalic acid (PTA) to make alipharomatic polyesters, can be obtained in mass amount from cellulose via bio- or chemical process. For this reason, FDCA-based polyesters have gained high interest recently. This review systematically summarizes recent progress in the making of FDCA-based polyesters (including poly(ethylene 2,5-furandicarboxylate) (PEF), poly(propylene 2,5-furandicarboxylate) (PPF), poly(butylene 2,5-furandicarboxylate) (PBF), poly(hexylene 2,5-furandicarboxylate) (PHF), and their copolyesters), especially highlighting the progress and fundamental aspects for their synthesis and properties. Significant advantages (and also disadvantages) of the FDCA-based polyesters are clearly indicated relative to price, performance, and sustainable development, in reference to traditional petroleum-based polyesters in industrial application. The goal of this review is to provide useful information regarding the synthesis and properties of FDCA-based polyesters.

Sugars, starches, and cellulose materials are used for ethanol production. When producing a liter of alcohol, 10 to 15 liters of liquid waste are generated. This waste is called vinasse, and it generates negative impacts on the environment. The process of storing and disposing vinasse in soils generates emissions to the atmosphere, mainly methane. Anaerobic treatment allows for the capture and generation of more biogas, therefore allowing mitigation of the environmental impacts. The microbial diversity present in the anaerobic digestion (AD) of vinasse is strongly related to the efficiency and quality of methane production. The gene 16s rDNA-based molecular techniques have been the most commonly used techniques for monitoring microbial communities present in the digesters. However, the identification is not enough. Rather, it is necessary to know the metagenomic functionality in this type of habitat. This review provides a comprehensive overview of methods to identify the microorganisms in the anaerobic digestion of vinasse. In addition, microbial community identification in vinasse reactors and their relationship with methane production are reviewed.