266 research outputs found
Lignocellulosic biomass utilization toward biorefinery: technologies, products and perspectives
Lignocellulosic biomass wastes (LBW)
are generated and accumulated in large
amounts around the world every year. The
disposal of large amounts of such wastes
in the nature may cause environmental
problems, affecting the quality of the
soil, lakes and rivers. In order to avoid
these problems, efforts have been directed
to use LBW in a biorefinery to maximize
the reutilization of these wastes with
minimal or none production of residual
matter. Through biorefinery, the biomass
is submitted to different conversion processes
that may include biological, physical
and chemical technologies to produce
fuels, power, heat, food, feed, and valueadded
chemicals. The products that can be
obtained as well as the technologies that
can be used for biomass disruption and
conversion vary according to the characteristics
of the LBW, such as the physical
properties and chemical composition
in terms of cellulose, hemicellulose, lignin
and protein contents [1]. By producing
multiple products through a biorefinery, the
value of the biomass feedstock is maximized,
which can be of particular interest in
countries with abundance of these wastes
and also in the underdeveloped countries
that can explore better their resources and
waste materials. In the future, a significant
increase in the implementation of biorefi-
nery processes for biomass valorisation is
expected motivated by the desire in reducing
the impact and toxicity of these wastes
to the environment and at the same time
to produce compounds of industrial interest
from competitive technologies based on the
use of low-cost raw materials. The creation
of more jobs is another positive and important
aspect related to the implementation of
these processes on industrial scale
Brewer's spent grain : a valuable feedstock for industrial applications
Brewer's spent grain (BSG) is the most abundant by-product generated from the beer-brewing process, representing approximately 85% of the total by-products obtained. This material is basically constituted by the barley grain husks obtained as solid residue after the wort production. Since BSG is rich in sugars and proteins, the main and quickest alternative for elimination of this industrial by-product has been as animal feed. However, BSG is a raw material of interest for application in different areas because of its low cost, large availability throughout the year and valuable chemical composition. In the last decade, many efforts have been directed towards the reuse of BSG, taking into account the incentive that has been given to recycle the wastes and by-products generated by industrial activities. Currently, many interesting and advantageous methods for application of BSG in foods, in energy production and in chemical and biotechnological processes have been reported. The present study presents and discusses the most recent perspectives for BSG application in such areas. © 2013 Society of Chemical Industry
Hydrothermal pretreatment of spent coffee and silverskin for polyphenols recovery
Coffee is one of the most consumed beverages around the world. As a
consequence of this big market, huge amounts of residues are also
generated every year as a result of the coffee beans processing. Spent
coffee grounds (SCG, Figure 1a), for example, are obtained in significant
amounts during the process for instant coffee elaboration, and is also
obtained in large amounts in restaurants, bars and cafeterias; while coffee
silverskin (CS, Figure 1b) is the main residue obtained during the beans
roasting step [1].
Interest in reusing these residues has increased in the last years for economic and environmental concerns.
Additionally, such coffee wastes contain in their composition several compounds of interest for application in food,
cosmetic and pharmaceutical areas [1]. The presence of polyphenols (PP) in SCG and CS has been reported in
several studies, and some technologies have also been proposed for the recovery of these compounds from such
coffee residues, among of which the use of organic solvents is usually proposed due to their efficient extraction
capacity. However, the use of organic solvents generates a toxic effluent that needs to be treated before discharging
to the environment. As an alternative to avoid this problem, the present study evaluated the possibility of recovering
PP by hydrothermal pretreatment of SCG and CS. By using this strategy, the residues are submitted to a reaction
using only water as extraction solvent under higher temperature conditions than those usually employed for
extraction with organic solvents, and the use of these toxic chemicals is avoided.
The hydrothermal pretreatment of SCG and CS consisted in using 20 mL of distilled water to each gram of residue,
and the reactions were maintained at 120 ÂșC during 20 min. The total amount of PP in the extracts was quantified as
gallic acid equivalents (GAE). The extracts produced under these conditions contained 32.9 mg GAE/g SCG and
19.2 mg GAE/g CS, among of which, flavonoids corresponded to 25% and 14% of the total PP in SCG and CS,
respectively. These results were higher than the amounts recovered in previous studies using organic solvents
(methanol and ethanol) as extraction agent [2, 3]. It was then concluded that is possible to use a hydrothermal
pretreatment to efficiently recover PP from coffee wastes. Further studies will be focused on the selection of the
extraction conditions that maximize the recovery results
Isolation of polyphenols from spent coffee grounds and silverskin by mild hydrothermal pretreatment
In the present study, a new method for isolation of polyphenols (PP) from spent coffee grounds (SCG) and coffee silverskin (CS) is described. The method consisted in a mild hydrothermal pretreatment at 120 °C, during 20 min, using a liquid to solid ratio of 20 ml/g. PP (determined as gallic acid equivalents, GAE) were the most abundant components in the extracts produced by this method, corresponding to 32.92 mgGAE/gSCG and 19.17 mgGAE/gCS, among of which, flavonoids corresponded to 8.29 and 2.73 mg quercetin equivalents/g of SCG and CS, respectively. Both extracts presented antioxidant activity but the results were higher for SCG extract, probably due to the highest content of PP present. Negligible effects (less than 1% solubilisation) were caused by the hydrothermal pretreatment on cellulose, hemicellulose and protein fractions of these materials. Some minerals elements were present in the extracts, potassium being the most abundant. Hydrothermal pretreatment under mild conditions was demonstrated to be an efficient method to recover antioxidant PP from coffee residues
Pretreatment and fermentation strategies to overcome the toxicity of acetic acid in hemicellulosic hydrolysates
Enzymatic hydrolysis of rice straw and glucose fermentation using a Vertical Ball Mill Bioreactor (VBMB): Impact of operational conditions
- âŠ