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• The chemical aspects of alum rosin sized paper degradation were described. • Direct influence of H 3 O+ ions formed during hydrolysis of aluminium(III) species. • Influence of pH variation on the redox potential of reactive oxygen species acting as oxidizing agent. In Europe, the use of aluminium(III) compounds, namely AlK(SO 4) 2 ·12H 2 O and later on Al 2 (SO 4) 3 ·18H 2 O for hardening gelatin sizes was recorded as early as the 16th century. This review is focused on the critical assessment of published data concerning the following chemical aspects of paper degradation: direct influence of H 3 O+ ions formed during hydrolysis of aluminium(III) species; influence of low-molecular organic acids formed within degradation processes; influence of pH variation on the redox potential of reactive oxygen species acting as oxidizing agent; consequences of the absorption of gaseous NO 2 and SO 2 present in the air for paper degradation; involvement of aluminium species in redox radical oxidation catalytic processes; possible effect of the coordination of Al(III) with small radius and high charge on oxygen atoms of cellulose carboxyl or hydroxyl groups. It is indicated how the understanding of the above mentioned effects can help slow down paper degradation. [ABSTRACT FROM AUTHOR]

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The vast amount of feathers generated (>1 Mtons/a in Europe) in the poultry industry is an opportunity of upcycling by-product materials and improving sustainable practices. Feathers are potentially interesting materials as feed protein ingredients due to their high protein (>85 wt%) and cystine content (>7 wt%). However, due to their challenging recalcitrant nature, they have to be processed to make feather protein suitably digestible. The objective was to investigate the effects of temperature (120oC–160oC) and time (10, 30, and 60 min) in thermal pressure hydrolysis of feathers on availability for enzymatic hydrolysis (AEH) and cystine conservation. AEH is defined as degree of degradation of processed feather protein by two digestive enzymes pepsin and pancreatin (Boisen). The present study identified and assessed four temperature stages that take place during feather processing. The four temperature stages are 120oC–135oC, 140oC–155oC, > 160oC, and the cooling-down phase. The second stage has the greatest influence on AEH. As well as temperature, hydrolysis time is also an essential parameter that had a major impact in the second stage (140oC–155oC). Both temperature and time influence negatively cystine content and stability. The present study demonstrates for the first time the importance of four reaction stages during feather hydrolysis and the impact of four stages on AEH of the obtained products. [ABSTRACT FROM AUTHOR]

Digestible maltodextrins are low-sweet saccharide polymers consisting of D-glucose units linked primarily linearly with alpha-1,4 bonds, but can also have a branched structure through alpha-1,6 bonds. Often, maltodextrins are classified by the amount of reducing sugars present relative to the total carbohydrate content; between 3 and 20 percent in the case of digestible maltodextrins. These relatively small polymers are used as food ingredients derived by hydrolysis from crops naturally rich in starch. Through advances in production technology, the application possibilities in food products have improved during the last 20 years. However, since glucose from digested maltodextrins is rapidly absorbed in the small intestine, the increased use has raised questions about potential effects on metabolism and health. Therefore, up-to-date knowledge concerning production, digestion, absorption, and metabolism of maltodextrins, including potential effects on health, were reviewed. Exchanging unprocessed starch with maltodextrins may lead to an increased glycemic load and therefore post meal glycaemia, which are viewed as less desirable for health. Apart from beneficial food technological properties, its use should accordingly also be viewed in light of this. Finally, this review reflects on regulatory aspects, which differ significantly in Europe and the United States, and, therefore, have implications for communication and marketing. [ABSTRACT FROM PUBLISHER]

The enzymatic hydrolysis of cellulose from biomass feedstock in the sugar-based biorefinery chain is penalized by enzyme cost and difficulty to approach the theoretical maximum cellulose conversion degree. As a consequence, the process is currently investigated to identify the best operating conditions with reference to each biomass feedstock. The present work reports an investigation regarding the enzymatic hydrolysis of apple pomace (AP). AP is an agro-food waste largely available in Europe that might be exploited as a sugar source for biorefinery purposes. A biomass pre-treatment step was required before the enzymatic hydrolysis to make available polysaccharides chains to the biocatalyst. The AP samples were pre-treated through alkaline (NaOH), acid (HCl), and enzymatic (laccase) delignification processes to investigate the effect of lignin content and polysaccharides composition on enzymatic hydrolysis. Enzymatic hydrolysis tests were carried out using a commercial cocktail (Cellic®CTec2) of cellulolytic enzymes. The effect of mixing speed and biomass concentration on the experimental overall glucose production rate was assessed. The characterization of the glucose production rate by the assessment of pseudo-homogeneous kinetic models was proposed. Data were analysed to assess kinetic parameters of pseudo-mechanistic models able to describe the glucose production rate during AP enzymatic hydrolysis. In particular, pseudo-homogeneous Michaelis and Menten, as well as Chrastil's models were used. The effect of lignin content on the enzymatic hydrolysis rate was evaluated. Chrastil's model provided the best description of the glucose production rate. [ABSTRACT FROM AUTHOR]