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Regardless of the considerable progress in properties and versatility of synthetic polymers, their low biodegradability and lack of environmentally-friendly character remains a critical issue. Pectin is a natural-based polysaccharide contained in the cell walls of many plants allowing their growth and cell extension. This biopolymer can be extracted from plants and isolated as a bioplastic material with different applications, including food packaging. This review aims to present the latest research results regarding pectin, including the structure, different types, natural sources and potential use in several sectors, particularly in food packaging materials. Many researchers are currently working on a multitude of food and beverage industry applications related to pectin as well as combinations with other biopolymers to improve some key properties, such as antioxidant/antimicrobial performance and flexibility to obtain films. All these advances are covered in this review.

Laccase is a versatile enzyme that plays a major role in the remediation of various environmental pollutants. In this work, a thermo-tolerant halophilic Bacillus aquimaris AKRC02 was isolated from pulp and paper mill waste sludge for efficient laccase production. Various agro-industrial waste residues, including potato peel, banana peel, sawdust, pea peel, wheat bran, orange peel, and rice bran, were screened to produce laccase using a submerged fermentation process. Among these, rice bran supported the maximum laccase production (4.58 U/mL). The optimized environmental conditions (incubation time 120 h; 4.58 U/mL), 35 0C; 6.624 U/mL) and pH 7.0; 10.142 U/mL) and nutritional sources (glucose 1.0%; 14.164 U/mL and peptone 0.5%; 18.124 U/mL) significantly enhanced the laccase production. Purified laccase showed a specific activity and purification fold of 228.34 U/mg and 38.08, respectively. The purified enzyme showed a molecular weight of 65 kDa and high thermal stability at 45 0C for 8 h. In conclusion, the remarkable properties of the newly isolated bacterium may provide a significant opportunity for degrading environmental contaminants, making it an attractive biocatalyst for industrial applications.Graphic Abstract

The Mediterranean area is one of the major global producers of agricultural food. However, along the entire supply chain—from farming to food distribution and consumption—food waste represents a significant fraction. Additionally, plant waste residues generated during the cultivation of specific fruits and vegetables must also be considered. This heterogeneous biomass is a valuable source of bioactive compounds and materials that can be transformed into high-performance functional products. By analyzing technical and scientific literature, this review identifies extraction, composite production, and bioconversion as the main strategies for valorizing agricultural by-products and waste. The advantages of these approaches as well as efficiency gains through digitalization are discussed, along with their potential applications in the Mediterranean region to support new research activities and bioeconomic initiatives. Moreover, the review highlights the challenges and disadvantages associated with waste valorization, providing a critical comparison of different studies to offer a comprehensive perspective on the topic. The objective of this review is to evaluate the potential of agricultural waste valorization, identifying effective strategies while also considering their limitations, to contribute to the development of sustainable and innovative solutions in Mediterranean bioeconomy.

Defatted seed meals of oleaginous Brassicaceae, such as Eruca sativa, and potato peel are excellent plant matrices to recover potentially useful biomolecules from industrial processes in a circular strategy perspective aiming at crop protection. These biomolecules, mainly glycoalkaloids and phenols for potato and glucosinolates for Brassicaceae, have been proven to be effective against microbes, fungi, nematodes, insects, and even parasitic plants. Their role in plant protection is overviewed, together with the molecular basis of their synthesis in plant, and the description of their mechanisms of action. Possible genetic and biotechnological strategies are presented to increase their content in plants. Genetic mapping and identification of closely linked molecular markers are useful to identify the loci/genes responsible for their accumulation and transfer them to elite cultivars in breeding programs. Biotechnological approaches can be used to modify their allelic sequence and enhance the accumulation of the bioactive compounds. How the global challenges, such as reducing agri-food waste and increasing sustainability and food safety, could be addressed through bioprotector applications are discussed here.

To promote the effective utilization of sludge and slag produced in nature and from human activities, this paper summarizes the research progress in the field of building materials on the basis of expounding their classification and characteristics. (1) Sludge and slag include silt, sludge and industrial waste residues. These three materials are mainly composed of SiO2, which can be used to produce building materials after treatment and can also be used as admixtures, including roadbed admixtures. (2) Silt and sludge are widely used in building wall materials and roadbed materials, etc. Industrial waste residues can be used in the production and processing of green concrete and glass-ceramics. (3) In addition to continuing to use existing utilization methods, key treatment technologies and new treatment devices can be further developed according to the characteristics of sludge and slag. Moreover, observations and mechanistic analysis of the microscopic structure of industrial waste residues and research on strong and weak utilization methods based on the performance of building materials can be carried out, and more efficient and energy-saving excitation or activation technologies will be developed. These efforts will eventually lead to the development of functional building materials with excellent performance and environmentally friendly characteristics to achieve the differentiated utilization of silt, sludge, and industrial waste residues and realize the efficient transformation of resources. This paper provides useful insights for the application of sludge and slag in the field of building materials.

The aim of this investigation is to determine the effects of hooked-end steel fibers on both the fresh and hardened properties of modified self-compacting concretes (SCC). For this purpose, the steel fibers are associated with other residue contents (i.e., marble, granite, and rubber). These concatenated material contents constitute a novelty since no investigations are reported. It is found that with the increase in rubber content, a better ability to absorb energy is observed. This indicates that a good alternative to structural material is provided. Fresh properties are evaluated by using flow, T500 time, V-funnel, and J-ring methods. The mechanical behavior is evaluated in terms of compressive strength, tensile strength, static and dynamic modulus of elasticity, and damping ratio. Experimental results of the water absorption, porosity, and density are also attained. It is also found that an SCC mixture containing steel fiber, marble/granite residue, and rubber content is a potential mixture to be considered when designing in SCC associated with an improved damping ratio. Although the rubber content decreases the mechanical behavior and slump flow, the concatenated utilization of marble/granite residues and steel fiber contents provides a slight improvement in the damping result. An environmental benefit can also be associated since cement consumption is decreased with marble additions.

Upgrading of food processing residues is currently a topic of global interest as scientists and industries have focused on using natural sources of antioxidants as an alternative to synthetic ones. The aim of the present work was to assess the potential of potato peel extracts of cultivars Gala and Jazzy in 96% ethanol, 80% ethanol and water by using antioxidant assays as well as model systems that contained food lipids. Extracts in 96% ethanol contained the highest amount of total phenolics (40.5 and 28.4 mg/g of dry weight) and showed the highest antiradical, reducing and iron-chelating potential, followed by extracts in 80% ethanol. The order of the extracts’ activity in β-carotene bleaching assay was strongly concentration-dependent. Potato peel extracts showed high efficiency in retarding oxidation of rapeseed oil, where they performed better than butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). They also delayed conjugated diene and volatile formation in sunflower oil. Compounds of potato peel extracts act via several mechanisms, assuring long-term protection of food lipids. They are a promising source of antioxidants that should be chosen carefully for a given medium in order to be stabilized and to obtain optimal results. The manner of potato peel valorization proposed here is in line with the global challenge to reduce food production waste residues and also gives an opportunity to extend the shelf life of food.

The influence of recycled fine aggregate content on the properties of soft soil solidified by industrial waste residue was systematically studied. First, the addition of recycled fine aggregate may provide skeleton support, which was conducive to improving the solidification properties. Comparing the addition of recycled fine aggregate content and a composite solidification agent separately, the compressive strength increased 48.01 times and 1.32 times, respectively. Second, the composition and quantity of the hydration products were analyzed by X-ray diffraction (XRD) and thermal gravity analysis (TG/DTG). In addition to silicon dioxide and aluminum oxide, a number of new minerals, including hydrated calcium silicate, calcium hydroxide and ettringite, were produced under different recycled fine aggregate contents. The diffraction peak of hydrated calcium hydroxide was weak, which indicated that the crystallinity and relative content was low. The main reason for this was that it was consumed as the activator of the secondary hydration reaction of blast furnace slag. With the increase in recycled fine aggregate content, the total weight loss (hydration products, crystal water, impurities) increased significantly, at rates of 6.9%, 7.0%, 7.2%, 8.8% and 9.7%. The addition of recycled fine aggregate does not change the composition and quantity of the hydration products, and the increased weight loss in this part might be caused by the cement paste attached to the surface of the recycled fine aggregate. Finally, their microstructure was analyzed by scanning electron microscopy (SEM). Larger and more pores appeared in the solidification system with the increase in recycled fine aggregate, and a large amount of ettringite was prepared. An excess in recycled fine aggregate caused more pores, and the negative impact of too many pores exceeded the lifting effect of the aggregate, resulting in the decline of its mechanical properties. Therefore, there was a suitable range for the use of recycled fine aggregate, which was not more than 40%. In conclusion, recycled fine aggregate not only acts as a skeleton to improve solidification strength, but could also realize the comprehensive utilization of waste, which provided a new scheme for solid waste utilization and soft soil solidification.

This study aims to research on the mechanical and frost resistance properties of pressed concrete blocks mixed with the polymeric aluminum chloride (PAC) waste residue. Experimental studies on the activity index of volcanic ash, mechanical property, frost resistance and microstructure of pressed concrete blocks mixed with PAC waste residue were carried out. The results show that the activity index of volcanic ash of PAC waste residue reaches 74.96% at a particle size of 0.075 mm or less and a curing age of 28 days. Based on results of mechanical property tests, the optimum dosage of PAC waste residue is 15%, at which time the compressive and bending strength only decreases by 14.57% and 15.84%. Based on results of frost resistance tests, the optimum dosage of PAC waste residue for pressed concrete blocks is 10%. After 50 freeze–thaw cycles, when the dosage of PAC waste residue is 10%, the strength loss rate is only 3.04%. XRD and SEM tests show that PAC waste residue participates in chemical reactions. With a small amount of PAC waste residue, the structure of the specimen remains dense and therefore the strength decreases less.

This paper determines the effect of calcination temperature on the activity of polymerized aluminum chloride (PAC) waste residue. The effect of the calcination temperature of PAC waste residue on the compressive strength of cement mortar was studied using the slurry substitution method. The compressive strength data of cement mortar mixed with different temperatures of calcined PAC waste residue were analyzed by fitting. A compressive strength prediction model of PAC waste residue calcination temperature on the compressive strength of cement mortar can be built. The effect of PAC waste residue on the volume stability of cement mortar was also studied. The results showed that calcination increased the activity index of PAC waste residue by 5 to 10%, and 600[degrees]C was the optimal calcination temperature. Compared with the uncal-cined PAC waste residue cement mortar, the calcined samples showed complete hydration, smaller micropores, and a denser overall structure. The fitting curve provided a good fit for the development of the compressive strength of cement mortar mixed with different temperatures of calcined PAC waste residue. A model of the calcination temperature of PAC waste residue on the compressive strength of cement mortar was derived based on the fitting curve. The volume stability of cement mortar mixed with PAC waste residue calcined at 600[degrees]C was improved. Keywords: activity index; calcination temperature; compressive strength; micro-morphology; polymerized aluminum chloride (PAC) waste residue; volume stability.