Heavy usage of gasoline, burgeoning fuel prices, and environmental issues have paved the way for the exploration of cellulosic ethanol. Cellulosic ethanol production technologies are emerging and require continued technological advancements. One of the most challenging issues is the pretreatment of lignocellulosic biomass for the desired sugars yields after enzymatic hydrolysis. We hypothesized that consecutive dilute sulfuric acid-dilute sodium hydroxide pretreatment would overcome the native recalcitrance of sugarcane bagasse (SB) by enhancing cellulase accessibility of the embedded cellulosic microfibrils.

The crystallinity index (CI) is often associated with changes in cellulose structure after biological and physicochemical pretreatments. While some results obtained with lignocellulosic biomass demonstrate a progressive increase in the CI as a function of pretreatments, it is also shown that the CI can significantly vary depending on the choice of the measurement method. Besides, the influence of the CI on the recalcitrance of biomass has been controversial for a long time, but the most recent results tend to point out that the efficiency of pretreatments in reducing the recalcitrance is not clearly correlated with the decrease of the CI. Much of this controversy is somewhat associated with the inability to distinguish between the CI of the cellulose inside the biomass and the CI of the full biomass, which contains other amorphous components such as lignin and hemicellulose. Cross polarization by multiple contact periods (Multi-CP) method was used to obtain quantitative 13C solid-state nuclear magnetic resonance (ssNMR) spectra of sugarcane bagasse biomass submitted to two-step pretreatments and/or enzymatic hydrolysis. By comparing the dipolar filtered Multi-CP 13C NMR spectra of untreated bagasse samples with those of samples submitted to acid pretreatment, we show that a 1% H2SO4-assisted pretreatment was very effective in removing practically all the hemicellulose signals. This led us to propose a spectral editing procedure based on the subtraction of MultiCP spectra of acid-treated biomass from that of the extracted lignin, to obtain a virtually pure cellulose spectrum. Based on this idea, we were able to evaluate the CI of the native cellulose inside the sugarcane bagasse biomass. The results show the validity of the proposed method as a tool for evaluating the variations in the CI of the cellulose inside biomasses of similar kinds. Despite a clear increase in the CI of biomass as measured by X-ray diffraction, no significant variations were observed in the CI of the cellulose inside the biomass after a particular 1% H2SO4/0.25–4% NaOH chemical-assisted pretreatments. The CI of cellulose inside the biomass solid fraction that remained after the enzymatic hydrolysis was also evaluated. The results show a slight increase in crystallinity.

Hybrid meat products are an excellent strategy to incorporate plant proteins into traditional meat formulations considering recent market trends focusing on the partial reduction in red meat content. In this work, we evaluated the effects of different concentrated plant proteins (soy, pea, fava bean, rice, and sunflower) in partially replacing meat in meat emulsion model systems. Soy, pea, and sunflower proteins showed great compatibility with the meat matrix, giving excellent emulsion stability and a cohesive protein network with good fat distribution. Otherwise, adding rice and fava bean proteins resulted in poor emulsion stability. Color parameters were affected by the intrinsic color of plant proteins and due to the reduction in myoglobin content. Both viscoelastic moduli, G′ and G″ decreased with the incorporation of plant proteins, especially for rice and fava bean. The temperature sweep showed that myosin denaturation was the dominant effect on the G′ increase. The water mobility was affected by plant proteins and the proportion between immobilized and intermyofibrillar water was quite different among treatments, especially those with fava bean and rice proteins. In vitro protein digestibility was lower for hybrid meat emulsion elaborated with rice protein. It is concluded that soy, pea, and mainly sunflower proteins have suitable compatibility with the meat matrix in emulsified products.