Antifungal Soybean Protein Concentrate Adhesive as Binder of Rice Husk Particleboards

Abstract

The aim of this research was to prepare an antifungal soybean protein concentrate (SPC) adhesive containing carvacrol (CRV) as a bioactive agent able to delay the attack of molds and yeast during storage of SPC adhesive at 4 °C as water-based systems. CRV was incorporated in SPC slurry at 0.5% v/v (~10 times its minimum inhibitory concentration against Aspergillus terreus, used as model fungus), to ensure its long-term action. CRV scarcely altered the thermal properties, structure and apparent viscosity of SPC adhesive. Active SPC aqueous dispersion was microbiologically stable for at least 30 days at 4 °C where the colonization begins, while control SPC was visually colonized from the second day. Rice husk (RH) particleboards of density ~900 kg/m3 were manufactured using the active SPC stored for 0, 10, 20, and 30 days as a binder. Modulus of elasticity, modulus of rupture and internal bond of RH–control SPC (without CRV) panels were 12.3 MPa, 2.65 GPa and 0.27 MPa, respectively, and were statistically unaltered compared with those obtained with fresh SPC, regardless of the presence of CRV or the storage time. This last implies that active SPC should not necessarily have to be prepared daily and/or be used immediately after its preparation. Since it is microbiologically stabilized, it can be store at least for 30 days, ensuring the stability of the protein. The quality of the adhesive was evidenced by the consistent properties of the adhesive, expanding its potential use and commercialization.

Sustainable Particleboards Based on Brewer’s Spent Grains

“…The processing conditions for the BSG particleboards were chosen based on our prior studies involving other substrates [ 12 , 28 ] and preliminary trials. Regardless of the applied pressing temperature, the pressure and pressing time for the binderless boards were maintained at 2.1 MPa and 15 min, respectively.…”

“…Although PAB boards exhibited significantly improved mechanical properties compared to those without a binder, the mechanical results observed in the obtained boards were even lower than those achieved using other substrates such as wood [ 81 ] or rice husk [ 12 ] combined with synthetic adhesive. The low MOE values of BSG boards might be related to their low cellulose content (9.5%), compared to, for example, eucalyptus wood (approximately 40%) and other lignocellulosic wastes like rice husk (30%) [ 12 , 24 , 27 , 28 ]. A similar reduction in MOE values was also observed by Barbu [ 13 ] when substituting spruce wood with BSG in particleboard using different synthetic adhesives.…”

“…Despite efforts to mitigate these emissions through stringent regulations and the development of alternative adhesives with scavengers for formaldehyde [ 20 ], the health effects persist, posing significant challenges to both manufacturers and consumers [ 23 , 24 ]. This has acted as a significant driving force towards the design of more benign adhesive formulations from bioderived resources such as carbohydrates [ 25 ], proteins [ 23 , 24 , 26 , 27 , 28 , 29 ], and biophenols such as cardanol [ 30 ], tannins [ 31 ], and lignins [ 32 , 33 ].…”

Antifungal Activity of Water-Based Adhesives Derived from Pineapple Stem Flour with Apple Cider Vinegar as an Additive

“…The suspension formed by A. niger and spores was collected and transferred to a sterile tube. The optical density (OD) of the suspension was adjusted to 0.05 using a UV–visible spectrophotometer at 600 nm, adapted by Su et al and Larregle et al [ 24 , 25 ].…”

Eco-Friendly Adhesives Based on the Oligomeric Condensed Tannins-Rich Extract from Alder Bark for Particleboard and Plywood Production

“…The study showed that the bending strength and internal bond strength of particleboards produced with the use of PVAc glue are lower than for panels produced with the use of UF resin [ 9 ]. In recent years, a considerable amount of research has been done on natural adhesives from sustainable resources such as lignin [ 10 , 11 , 12 ], soybean [ 12 , 13 , 14 ], condensed tannins [ 15 , 16 , 17 , 18 ], and suberinic acids [ 19 ] in the partial of full replacement of PF. Condensed tannins (CTs) from lignocellulosic biomass could potentially be eco-friendly substitutes for phenol in adhesives due to the high reactivity of CTs toward aldehydes, including formaldehyde [ 20 ].…”