Hornification: Lessons learned from the wood industry for attenuating this phenomenon in plant‐based dietary fibers from food wastes

Abstract

A significant amount of waste is annually generated worldwide by the supply chain of the food industry. Considering the population growth, the environmental concerns, and the economic opportunities, waste recovery is a promising solution to produce valuable and innovative ingredients for food and nonfood industries. Indeed, plant-based wastes are rich in dietary fibers (DF), which have relevant technical functionalities such as water/oil holding capacity, swelling capacity, viscosity, texture, and physiological properties such as antioxidant activity, cholesterol, and glucose adsorption capacities. Different drying technologies could be applied to extend the shelf life of fresh DF. However, inappropriate drying technologies or process conditions could adversely affect the functionalities of DF via the hornification phenomenon. Hornification is related to the formation of irreversible hydrogen bindings, van der Waals interactions, and covalent lactone bridges between cellulose fibrils during drying.This review aims to capitalize on the knowledge developed in the wood industry to tackle the hornification phenomenon occurring in the food industry. The mechanisms and the parameters affecting hornification as well as the mitigation strategies used in the wood industry that could be successfully applied to foods are summarized. The application of conventional drying technologies such as air or spray-drying increased the occurrence of hornification. In contrast, solvent exchange, supercritical drying, freeze-drying, and spray-freeze-drying approaches were considered effective strategies to limit the consequences of this phenomenon. In addition, incorporating capping agents before drying attenuated the hornification. The knowledge summarized in this review can be used as a basis for process design in the valorization of plant-based wastes and the production of functional DF that present relevant features for the food and packaging industries.

Enhanced Internal Coating Structure and Light Reflectance of Coated Papers: A Sludge Valorization Process

“…23 Yet, inappropriate drying technologies could adversely affect the cellulose functionalities due to the hornification phenomenon, which means irreversible hydrogen-bonding formations, van der Waals interactions, and covalent lactone bridges between cellulose fibrils during drying. 24,25 Recent studies have focused on converting cellulose into cellulose nanofibers (CNFs) to produce high-value-added materials. 26,27 Due to the resultant CNFs having a high aspect ratio and a large number of interfibril hydrogen bonds, the resultant product contributes to high strength and stiffness properties.…”

“…PMS valorization reduces waste and has a negative feedstock cost. , In a previous study, cellulose extracted from PMS was used as filler reinforcement for composites, which increased the bending modulus to 2277 MPa with the addition of 40% PMS and the bending strength to 15.10 MPA with the addition of 30% PMS. , It was also used as an adsorbent to remove hydrophobic substances. , One study highlighted that when PMS is transported over 50 km from the mill for processing, dried sludge is preferred over never-dried sludge for production . Yet, inappropriate drying technologies could adversely affect the cellulose functionalities due to the hornification phenomenon, which means irreversible hydrogen-bonding formations, van der Waals interactions, and covalent lactone bridges between cellulose fibrils during drying. , …”

“…The hypothesis of this study is that the addition of CNFs made by the cellulose extracted from PMS may enhance the internal coating structure of paper and light reflectance of coated papers due to the unique features of CNFs. To the best of our knowledge, no previous research has been found to study the effects of CNFs PMS addition in paper coatings and surface treatment, which enables on-site valorization of never-dried PMS and cut down the transportation cost and the need for drying, which causes hornification . The purpose of this research is to convert PMS into CNFs PMS and apply it on a paper surface using a scalable wire-wound rod coating method to investigate if the following three experimental factors could enhance the structural and optical properties of paper: (i) CNFs PMS addition in paper coating at 0, 1, 2, and 3 wt % pigments; (ii) coating at one and two layers; and (iii) surface treatment using calendering at 0 and 500 pounds per linear inch (pli) via a 4 × 2 × 2 factorial design (Figure ).…”

“…To the best of our knowledge, no previous research has been found to study the effects of CNFs PMS addition in paper coatings and surface treatment, which enables on-site valorization of never-dried PMS and cut down the transportation cost and the need for drying, which causes hornification. 24 The purpose of this research is to convert PMS into CNFs PMS and apply it on a paper surface using a scalable wire-wound rod coating method to investigate if the following three experimental factors could enhance the structural and optical properties of paper: (i) CNFs PMS addition in paper coating at 0, 1, 2, and 3 wt % pigments; (ii) coating at one and two layers; and (iii) surface treatment using calendering at 0 and 500 pounds per linear inch (pli) via a 4 × 2 × 2 factorial design (Figure 1). The change in formulation, coating layer, and surface treatment was tracked by the structural property responses of porosity, air permeability, thickness, and roughness and optical property responses of brightness, gloss, and CIE L*a*b*.…”