<p>The aim of this work was to study the possible complex formation between chitosan and phytic acid. Zeta potential and turbidity measurements were used as a basis to confirm the possible complex between these two molecules. The obtained results showed that chitosan at a concentration of 0.1% (w/v) were soluble in 0.1% acetic acid solution. This concentration of the acetic acid was the lowest that allows chitosan to dissolve. A positive surface charge of chitosan was recorded in the pH interval from 1 to 7. The highest zeta potential values were obtained at pH &lt; 5 and decreased significantly at pH 6 and 7. Regarding phytic acid, it was soluble in deionized water and acetic acid whatever the concentration of the acetic acid and in the entire pH range 2-10. Phytic acid had negative surface charge in deionized water and in 0.1% acetic acid, but was slightly positively charged in 5% acetic acid solution. The solubility of chitosan was decreased by the presence of phytic acid. The formation of chitosan/phytic acid complex as monitored by measuring the zeta potential does not allow us to conclude that the formation of this complex is possible.</p>

No abstract

No abstract

Highlights Sweet sorghum and sweet pearl millet are interesting feedstocks for ethanol production. Biomass and juice storage are key steps for carbohydrate preservation. Produced bagasse can be valorized in many ways, including as silage or for cellulosic ethanol production. Abstract. Sweet sorghum and sweet pearl millet have been considered as potential energy crops. They have many advantages in terms of ethanol production compared to corn and sugarcane, such as lower requirements for water and fertilizers, higher tolerance to drought, and lower competition with the food sector. Sweet sorghum and sweet pearl millet stems are rich in water-soluble carbohydrates (WSC) (sucrose, fructose, and glucose), and their biomass has to be crushed for juice extraction. However, the extraction efficiency of WSC varied widely depending on the press type used and the parameters considered during the pressing process (stripping stems from leaves or not, compressive force magnitude, smooth or grooved press rollers, number of times of biomass pressing, etc.). WSCs are easily degradable, causing technical challenges related to crop handling before pressing and juice storage thereafter. Some studies focused on stem preserving methods, whereas others dealt with extending the shelf life of the juice. To make the use of sweet sorghum and sweet pearl millet as energy crops more profitable, the bagasse (residue) generated from biomass pressing can be valorized in different ways, mainly as silage or for second generation ethanol production. The objective of this review was to assess the efficiency of different presses used for juice extraction and discuss various methods tested for WSC conservation from deterioration as well as possible bagasse valorization. Keywords: Bagasse, Carbohydrates, Ethanol, Press, Sweet pearl millet, Sweet sorghum.

HighlightsJuice extraction resulted in a decrease in the nutritive value of the bagasse as compared with the initial biomass.Silages made from the second pressing bagasse were well conserved.Sweet sorghum silage has a better nutritive value than sweet pearl millet.Abstract. Pressing the biomass of sweet sorghum and sweet pearl millet in-field is one of the suggested options for bioethanol production. The extracted juice can be delivered to an ethanol plant, and the bagasse (pressing residue) can be used for ruminant feeding. Efficient carbohydrate extraction is highly important for good ethanol yield. However, enough carbohydrates must remain in the bagasse for its adequate conservation as silage. In this study, the ensilability and the chemical composition of the second pressing bagasse of sweet sorghum and sweet pearl millet were investigated. The bagasse was obtained following a second pressing of the first pressing bagasse after its impregnation with water based on three water:bagasse ratios (0.5, 1, and 1.5). Results indicated that water:bagasse ratio did not affect water-soluble carbohydrate (WSC) extraction for both crops. The second pressing bagasse of sweet sorghum and sweet pearl millet contained 80.5 ±4.6 and 60 ±4.6 g of WSC kg-1 dry matter (DM), respectively. The second pressing bagasse of both crops had reduced nutritive value compared to the initial biomass, i.e., higher neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations along with lower non-structural carbohydrate (NSC) concentration, in vitro true digestibility of DM (IVTD), and in vitro NDF digestibility (NDFd). The second pressing bagasses of both crops also showed good ensilability, but sweet sorghum bagasse silages were of better nutritive value than sweet pearl millet bagasse silages (ADF = 446.2 ±3.7 vs. 463.2 ±3.7 g kg-1 DM, IVTD = 813.8 ±3.4 vs. 708.8 ±6.8 g kg-1 DM, and NDFd = 741.8 ±4.8 vs. 596.2 ±8.5 g kg-1 NDF, respectively). The water:bagasse ratio used for bagasse impregnation before the second pressing only affected the NDF concentration of silages, as a higher NDF concentration was obtained with a water:bagasse ratio of 1.5. Sweet sorghum and sweet pearl millet can be considered dual-purpose crops; the extracted juice can be fermented into ethanol, and the second pressing bagasse can be used to make good-quality silage. Keywords: Bagasse impregnation, Nutritive value, Silage, Sweet pearl millet, Sweet sorghum, Water-soluble carbohydrates.