Comparing Condensed and Hydrolysable Tannins for Mechanical Foaming of Furanic Foams: Synthesis and Characterization

Eckardt, Jonas; Sepperer, Thomas; Cesprini, Emanuele; Šket, Primož; Tondi, Gianluca

doi:10.3390/molecules28062799

Cited by 8 publications

(4 citation statements)

References 51 publications

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“…Tannins are water-soluble polyphenolic compounds that are synthesised as mechanical defence mechanisms to prevent plants from being consumed by animals. Terrestrial plants synthesise two classes of tannins, which are condensed and hydrolysable tannins [1,2]. Condensed tannins are made up of flavan-3-ols and flavan-3,4-diols, while hydrolysable tannins are made up of gallotannins and ellagitannins [3].…”

Section: Introductionmentioning

confidence: 99%

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage

Mpanza,

Mani

2023

Microorganisms

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Maize silage is produced to alleviate the effects of forage shortages on ruminant animals, particularly during the dry season. Microorganisms play a significant role in silage fermentation and thus, to a large extent, determine the silage quality. The modulation of silage microorganisms may help to inhibit undesirable bacteria and improve the silage quality. Therefore, condensed tannin extract from Vachellia mearnsii bark was used as an additive in maize silage during ensiling. Hence, this study evaluated the effects of a tannin extract (condensed tannin) additive on the fermentative quality, aerobic stability, and bacterial composition of maize silage. A mini-silo experiment on maize with five treatments was conducted for 75 days. The silage treatments were as follows: (T1) maize forage with no inoculation (negative control); (T2) maize forage inoculated with LAB and 1% tannin extract; (T3) maize forage inoculated with LAB only (positive control); (T4) and maize forage inoculated with LAB and 2% tannin extract; (T5) maize forage inoculated with LAB and 3% tannin extract. The results showed that the additives modulated the silage microorganism composition. However, this was without affecting the silage’s fermentative quality and aerobic stability. All the silages recorded a pH below 4.2, which indicated well-fermented silage. The tannin extract suppressed the growth of undesirable bacteria, such as Dysgonomonas, Gluconacetobacter and Clostridium genera, while promoting desirable bacteria, such as Lactobacillus and Weissella genera, which were attributed to the silage quality. It is thus concluded that tannins can be strategically used as silage additives to modulate the microbial composition of silage and improve the silage quality by promoting the dominance of the desirable bacteria in the silage.

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Section: Introductionmentioning

confidence: 99%

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage

Mpanza,

Mani

2023

Microorganisms

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“…Under acidic conditions, tannins and furfuryl alcohol can undergo co-condensation reactions to obtain tannin–furan (TF) foams. This foam has attractive properties such as a light weight, excellent refractoriness, and thermal insulation [ 19 , 20 , 21 ]. However, the self-condensation reaction of furfuryl alcohol occurs under acidic conditions, which dominates the reaction, and almost no co-condensation reaction with tannins occurs [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of Biomass Tannin-Based Flexible Foam Insoles for Athletes

Zuo,

Liu,

Essawy

et al. 2023

Polymers

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The exploitation of bio-based foams implies an increase in the use of renewable biological resources to reduce the rapid consumption of petroleum-derived resources. Both tannins and furfuryl alcohol are derived from forestry resources and are, therefore, considered attractive precursors for the preparation of tannin–furanic foams. In addition, toughening modification of tannin–furanic foams using polyvinyl alcohol (PVOH) results in a more flexible network-like structure, which imparts excellent flexibility to the foams, whose relative properties are even close to those of polyurethane foams, which are the most used for fabrication of insoles for athletes. In addition, the addition of PVOH does not affect the thermal insulation properties of the foams by testing the thermal conductivity, resilience, and elongation at break, while reducing the brittleness of the samples and improving the mechanical properties. Also, the observation of the morphology of the foam shows that the compatibility between PVOH and tannin–furanic resin is good, and the cured foam does not show fragmentation and collapse, while the bubble pore structure is uniform. The developed flexible foam derived from biomass resources endows the foam with good thermal insulation properties and high mechanical properties, and the samples exhibit suitable physical parameters to be used as flexible insoles for athletes.

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“…Despite the development of TF showing a favorable trend, there was a very serious problem that plagued many research groups, which was its high pulverization ratio. The basic properties of different types of TF were evaluated, in which it was evident that there were significant differences between due to tannin's characteristics [7]. It is well known that the activities of tannin resources are highly related to their flavonoid unit types and quantity [8].…”

Section: Introductionmentioning

confidence: 99%

An Investigation into the Relationship between Density and Pulverization Ratio for Tannin-Furanic Foam

Yuan,

Essawy,

Ding

et al. 2023

Materials

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Four types of classical tannin-based foam samples were prepared via different methods in the current study with an attempt to find out the impact of each one on the physico-mechanical properties. The results of performed tests showed similarity to the general trend of related research, with typical negative relation between the foam density and mechanical strength. A critical point was found for each type of foam samples, for example, for tannin-formaldehyde foams (TFF), they were in the range of 85–95 kg/m3, while for tannin-glutaraldehyde foams (TGF), mechanically-generated tannin foams (MTF) and steam-driven tannin furanic foams (STDF), they were about 52–62 kg/m3, 53–63 kg/m3, and 73–83 kg/m3, respectively. This implies a significant change for density and mechanical strength, has been dig out by intensive experimental results and analysis. In addition, a non-liner relationship between density and pulverization ratio was obtained by fitting the curves obtained by the experiment results. Finally, visualization using scanning electron microscopy (SEM) together with evaluation of the compression strength presented a deeper insight to illustrate the different factors affecting foam density and pulverization ratio.

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Comparing Condensed and Hydrolysable Tannins for Mechanical Foaming of Furanic Foams: Synthesis and Characterization

Cited by 8 publications

References 51 publications

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage

Preparation and Characterization of Biomass Tannin-Based Flexible Foam Insoles for Athletes

An Investigation into the Relationship between Density and Pulverization Ratio for Tannin-Furanic Foam

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