Leandro Soares Oliveira

Leandro Soares Oliveira
Federal University of Minas Gerais | UFMG · Departamento de Engenharia Mecânica (DEMEC)

PhD

About

160
Publications
171,365
Reads
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5,033
Citations
Citations since 2017
39 Research Items
3138 Citations
20172018201920202021202220230100200300400500600
20172018201920202021202220230100200300400500600
20172018201920202021202220230100200300400500600
20172018201920202021202220230100200300400500600
Additional affiliations
January 2008 - present
Federal University of Minas Gerais
Position
  • Professor (Associate)
January 2008 - present
Federal University of Minas Gerais
Position
  • Fluid Mechanics
September 1996 - December 2007
Federal University of Minas Gerais
Position
  • Universidade Federal de Minas Gerais
Education
August 1991 - October 1995
Purdue University
Field of study
  • Agricultural and Biological Engineering
March 1989 - June 1991
Federal University of Minas Gerais
Field of study
  • Mechanical Engineering
March 1983 - December 1988
Federal University of Minas Gerais
Field of study
  • Chemical Engineering

Publications

Publications (160)
Article
Full-text available
The present work proposes the use of an agro-industrial residue from the sunflower crop as a feedstock to produce a low-cost adsorbent with a chemically modified surface bearing sulfonic groups. This modified low-cost adsorbent can be used for the removal of phenylalanine, and can also be applied in the process of obtaining a source of protein supp...
Article
Full-text available
The feasibility of using epoxidized waste cooking oils as a partial replacement for synthetic resins in the manufacture of lignocellulosic composites where the reinforcement is comprised of mechanically ground wood from civil construction waste wood (CCWW) was investigated. For this study, the wood-epoxy composite was prepared using the thermo-curi...
Article
Full-text available
Current estimates place the amount of spent coffee grounds annually generated worldwide in the 6 million ton figure, with the sources of spent coffee grounds being classified as domestic (i.e., household), commercial (i.e., coffee houses, cafeterias and restaurants), and industrial (i.e., soluble and instant coffee industries). The majority of the...
Article
Full-text available
Cassava peels are wastes generated worldwide in large amounts by the cassava processing industry. Although some studies have highlighted its application for animal feed, a more profitable use for these residues has not yet been implemented. Thus, the aim of this study was to extract starch from the peels of cassava and to characterize its physical,...
Article
Full-text available
Coffee husks are a major by-product of coffee production and are currently being underutilized. The aim of this work was to chemically characterize coffee husks to allow for an adequate evaluation of their potential for valorization. Blanched and non-blanched coffee husks were characterized for extractable and non-extractable phenolics, caffeine, t...
Article
Oil-in-water (O/W) emulsions stabilized by cellulose nanocrystals (CNC) and/or sunflower proteins (SFP) were produced, aiming to study the effects of each and the mixture of these stabilizers on the interfacial behavior and physicochemical properties of O/W emulsions. The presence of CNC (non-surface activity compound) did not affect SFP solutions'...
Article
Full-text available
Umbu, a common fruit from the northeastern region of Brazil, contains many bioactive compounds not yet exploited. Thus, this study evaluated the potential of pulps and peels of mature and semi-mature umbu as a source of bioactive compounds. Trigonelline contents ranged from 1.75 to 6.14 mg/100 g, values higher than those of many vegetables describe...
Article
Epoxidized soybean oil was produced in this study by in situ generated peroxycitric with citric acid and hydrogen peroxide. Different production techniques were applied, namely conventional heating epoxidation and microwave-assisted epoxidation, using the Prileschajew method. Three different processes were studied in the conventional heating proces...
Article
Full-text available
Enzymatic browning is one of the limiting factors in extending the shelf-life of food products. Since the chemical composition can differ depending on fruit species and variety, browning prevention treatments may not always present the same efficacy. The goal of this study was to verify if differences between two fresh-cut apple varieties, Granny S...
Chapter
The continuous increase of consumer demand for high quality food products and the close relationship between food safety and human health has kept the food industry in constant growth and development. Traditional detection technologies for food quality and safety evaluation are usually restricted, due to high costs, lengthy time demands, bulky inst...
Article
Jabuticaba peels present high levels of bioactive compounds. The production of flours from these peels can be a strategy for their conservation. Thus, the objectives of this study were to produce flours from jabuticaba peels, to examine the feasibility of employing Fourier Transform Infrared (FTIR) measurements for their chemical characterization a...
Article
Full-text available
Some additives used in polymeric products can cause health problems; thus, lowering migration of such substances from the polymeric matrix is of concern. Given that migration is sometimes inevitable, the use of safe additives is an alternative. This work demonstrates the viability of employing generally recognized as safe (GRAS) substances (citric...
Article
Spent coffee grounds are wastes generated annually worldwide in significantly large amounts in the soluble coffee industry and in household and commercial beverage preparation. Although spent coffee grounds are rich in several classes of compounds, predominantly polysaccharides, profitable applications have not yet been effectively implemented for...
Article
The search for new renewable sources for the development of biopolymer packaging has been growing. Among these are galactomannans due to their biodegradability, high availability, and biocompatibility. The objective of this work was to develop biopolymeric film comprised mostly of galactomannans recovered from spent coffee grounds through alkaline...
Article
This article aims to develop and validate a multivariate model for quantifying Robusta-Arabica coffee blends by combining near infrared spectroscopy (NIRS) and total reflection X-ray fluorescence (TXRF). For this aim, 80 coffee blends (0.0-33.0%) were formulated. NIR spectra were obtained in the wavenumber range 11100-4950 cm⁻¹ and 14 elements were...
Article
Full-text available
Cup tasting is the most important tool to access the quality of coffee beans. However, the use of sensory evaluation alone can present some problems, since bias from the previous knowledge of a particular sample and health conditions of the taster can influence the results. Given the well-established potential of spectroscopic methods in coffee qua...
Article
This work aimed to characterize the fuel properties and to evaluate the kinetics of thermal decomposition of defective coffee beans (DCB). Three thermogravimetric-based methods were evaluated: Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS) and Friedman. The results showed that DCB presented low activation energy and that the evaluated mathe...
Article
Biodiesel is produced by transesterification reaction of oils catalyzed by homogeneous catalysts, with the latter being non-recoverable and promoter of solubility of the produced glycerol into the otherwise immiscible ester phase, which have to be purified. The need for purification of products is eliminated if heterogeneous catalysts are employed,...
Article
Buriti by-products flours were evaluated as sources of dietary fibers and natural antioxidants. All flours presented chemical characteristics that allowed classification as high dietary fiber powders. Presence of pectic polysaccharides, arabinoxylans and xyloglucans was inferred by the neutral monosaccharides profile. Peels and defatted pulp flours...
Article
This paper describes a robust multivariate model for quantifying and characterizing blends of Robusta and Arabica coffees. At different degrees of roasting, 120 ground coffee blends (0.0–33.0%) were formulated. Spectra were obtained by two different techniques, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and pape...
Article
Biodiesel was successful produced in a microwave irradiation reactor using homogeneous and heterogeneous catalysis. The biodiesel was production by the trasesterification reaction of soybean oil using metanol. Sodium methylate (30% solution in metanol) was used for the homogeneous catalyst and the heterogeneous catalyst was developed using wasted e...
Article
Full-text available
This paper combined attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), multivariate calibration with partial least squares (PLS), and different variable selection methods for the development of models to determine Robusta-Arabica coffee blends in the analytical range from 0.0 to 33.0% w/w. Ground samples of different o...
Article
Coffee cup quality, determined by the sensory attributes evaluated by professional tasters, is a decisive factor for evaluating coffee, with the "Specialty Coffee Association of America" (SCAA) classification being nowadays considered the most suitable. Panels of trained coffee tasters are used by the industry to describe and evaluate beverage qual...
Article
For the past decade, environmentally friendly features have been one of the most desired characteristics of most of the arising technologies. The search for materials from renewable sources and the development of novel non-hazardous processes for their production is currently of the utmost relevance. However, significant improvements on the current...
Article
Sensory (cup) analysis is a reliable methodology for green coffee quality evaluation, but faces barriers when applied to commercial roasted coffees due to lack of information on roasting conditions. The aim of this study was to examine the potential of mid-infrared spectroscopy for predicting cup quality of arabica coffees of different roasting deg...
Article
Extraction of pectin from pequi peel using microwave heating was investigated in this study. Pectin extraction was optimized by a central composite rotational design varying microwave power, extraction time and temperature. Pectin yield ranged from 9.91 to 20.79 g/100 g. Temperature and microwave power significantly affected the yield of pectin ext...
Article
Full-text available
This paper proposes a novel screening method for the simultaneous detection of four adulterants (spent coffee grounds, roasted coffee husks, roasted corn, and roasted barley) in ground roasted coffee using partial least squares discriminant analysis (PLS-DA) with mid-infrared spectroscopy. Two different acquisition modes (attenuated total reflectan...
Article
The potential of pequi by-products as substrates for the production of flours rich in antioxidant dietary fibers was evaluated. Dietary fiber contents ranged from 39.8 to 43.3 g/100 g with pectic polysaccharide fraction constituted of rhamnogalacturonans and hemicellulose fraction consisted of arabinogalactans, xylans and glucomannans. Total polyph...
Article
The designation of origin of high-value agricultural and food products has become increasingly relevant for the producers, since it allows the consumers to relate the singular characteristics of their preferred product to its respective provenance. Thus, coffee producers are in pursuit of ways to certify their products according to their authentici...
Article
Full-text available
Raphanus sativus press cake, a solid residue from biodiesel production, was evaluated as precursor material for the production of adsorbents. A comparative evaluation of acid and basic activating agents is presented, as well as conventional and microwave carbonization. The treatment that provided best adsorption performance was microwave activation...
Article
Full-text available
This paper proposed the joint use of Fourier Transform Infrared Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and Partial Least Square (PLS) regression for the simultaneous quantification of four adulterants (coffee husks, spent coffee grounds, barley, and corn) in roasted and ground coffee. Roasted coffee samples were intentionally blended...
Article
The preparation of coffee beverage, as well as the industrial production of soluble coffee, generates a considerable amount of residues, the spent coffee grounds, SCG. There are no current profitable applications for these residues and an adequate disposal must be carried out since they are heavily pollutant and can be used to adulterate roasted an...
Chapter
Coffee is one of the most popular beverages consumed worldwide and the most important food commodity from an economic point of view. Coffee processing can be divided into two stages: primary processing, in which the coffee fruits are de-hulled and submitted to drying, the resulting product being the green coffee beans, the main product of internati...
Chapter
Coffee is one of the top commodities produced and commercialized worldwide, and the processing of coffee generates significant amounts of agricultural waste, ranging from 30% to 50% the weight of the total coffee produced, depending on the type of processing. Coffee husks and pulp are the major solid residues from the processing of coffee, for whic...
Chapter
Green coffee is the major product in coffee international trade, and its quality is directly affected by the presence of defective coffee beans. Such defective beans are usually separated by color sorting from the nondefective ones prior to commercialization. However, color separation is not effective and color sorting machines are usually set up t...
Article
Full-text available
This paper presents a comparative evaluation of two activated carbons produced from different lignocellulosic residues (spent coffee grounds and Raphanus Sativus press cake), as adsorbents for removal of phenol from aqueous solutions in fixed-bed column studies. Both the prepared adsorbents presented outstanding adsorption capacities when compared...
Article
Full-text available
Corn cobs were evaluated as raw material in the production of an adsorbent for phenol removal from aqueous solutions. Adsorption kinetics and equilibrium were satisfactorily described by the pseudo second-order and Freundlich models, respectively. Fixed bed adsorption (breakthrough curve) was satisfactorily described by Bohart-Adams, Yoon-Nelson an...
Article
Full-text available
Coated electrodes are used in manual welding, with the coating being comprised of a variety of ingredients, including the binder, usually sodium or potassium silicate. In recent studies aiming at waterproof electrodes, the usual binders were successfully replaced by hydrophobic polymers. In this study, the use of epoxidized soybean oil (ESO) as wel...
Article
Full-text available
A common problem that affects the continuous casting process is the formation of a sink funnel or a vortex funnel in the end of the teeming process of a steel ladle. This causes the slag to be carried over with the molten steel to the tundish, generating inclusions in the produced steel ingot. In this work we propose an innovative device designed t...
Article
Full-text available
In this paper, we propose a feasible, sample preparation free and fast validated methodology for the detection and quantitative analysis of Minas Frescal cheese waste whey as an adulterant in raw milk using mid-infrared spectroscopy with Fourier transform (FTMIR) along with the chemometric technique of partial least squares (PLS). The PLS model was...
Article
Full-text available
Melanoidins are colored products that can be found in food and drinks, formed by Maillard reactions. Sometimes these compounds are considered undesirable in certain food products, because they impart a brownish color and must be removed. An overview of recent patents related to melanoidin removal indicates that it can be performed by chemical/biolo...
Article
Full-text available
Agricultural residues were evaluated as raw material in the production of adsorbents for phenol removal from aqueous solutions. A comparative evaluation of acid and basic activating agents is presented. Adsorption kinetics and equilibrium were satisfactorily described by the pseudo second-order and Freundlich models, respectively. Adsorption tests...
Article
Full-text available
Biodiesel was produced by microwave-assisted transesterification of soybean oil with methanol as esterifying agent and sodium methoxide as catalyst. Fourier transform infrared spectroscopy was employed as a fast and reliable analytical technique for the quantification of fatty acid methyl ester content in the produced biodiesel. The quantification...
Article
Full-text available
This study evaluates the potential of Crambe abyssinica press cake, a residue from crambe oil extraction and/or biodiesel production, as an adsorbent for removal of cationic dyes from wastewaters. Batch adsorption tests were performed at 30, 40 and 50˚C. Adsorption kinetics and equilibrium were satisfactorily described by the pseudo second-order an...
Article
Full-text available
In the continuous casting process, significant amounts of molten steel are left in the ladle during teeming as an established practice to avoid vortexing funnel formation in the end of the teeming process, preventing the ladle slag to be carried over to the tundish. Thus, it was the objective of this work to experimentally and numerically analyze t...
Article
Full-text available
This paper presents a comparative evaluation of three lignocellulosic residues (coffee husks, spent coffee grounds and pequi husks) as precursor materials in the production of activated carbons (ACs). Results indicate that the precursor material has a significant effect in both physical and chemical aspects of the adsorbent, with the AC based on sp...
Article
The quality of the coffee beverage is negatively affected by the presence of defective coffee beans and its evaluation still relies on highly subjective sensory panels. To tackle the problem of subjectivity, sophisticated analytical techniques have been developed and have been shown capable of discriminating defective from non-defective coffees aft...
Article
Full-text available
This paper presents a comparative evaluation of three lignocellulosic residues (corn cobs, spent coffee grounds and Raphanus sativus press cake) as precursor materials in the production of activated carbons (ACs). Results indicate that the precursor material has a significant effect in both physical and chemical aspects of the adsorbent as well as...
Article
Full-text available
Welding with coated (covered) electrodes is a manual process in which an electric arc is generated between the electrode and work piece to melt the metals at the welding point whereby they are joined. Among the several ingredients that constitute the electrode coating, there is the binder, which is usually sodium or potassium silicate. Recently, st...
Article
The current study presents an application of Diffuse Reflectance Infrared Fourier Transform Spectroscopy for detection and quantification of fraudulent addition of commonly employed adulterants (spent coffee grounds, coffee husks, roasted corn and roasted barley) to roasted and ground coffee. Roasted coffee samples were intentionally blended with t...
Article
The quality of roasted and ground coffee is an important issue since it has been the target of fraudulent admixtures with a variety of cheaper materials, including spent coffee grounds, coffee husks and other roasted grains. Given the successful application of Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) for discrimination b...
Article
Full-text available
Alcohol and triglycerides do not form a single phase mixture and thus there is a poor surface contact between them causing transesterification to proceed relatively slow. Introduction of stirring improves the surface contact and consequently the reaction rates and biodiesel yields. Thus, in industrial processes, transesterification is usually carri...
Article
a b s t r a c t Corn cobs were evaluated as raw material in the production of an adsorbent for phenylalanine removal from aqueous solutions. Batch adsorption studies were conducted at 25, 35 and 45 C, respectively. Adsorption equilibrium was attained after 3 h and Langmuir, Freundlich, Temkin, and Langmuir eFreundlich models were tested for equilib...
Article
Coffee has been the target of fraudulent admixtures with cheaper materials, including coffee husks and other roasted grains. Given the successful application of spectroscopic methods in the field of food adulteration as fast and reliable routine techniques, the objective of this work was to evaluate the feasibility of employing Diffuse Reflectance...
Article
Full-text available
Adsorption of phenolic amino acids, such as phenylalanine and tyrosine, is quite relevant for the production of protein hydrolysates used as dietary formulations for patients suffering from congenital disorders of amino acid metabolism, such as phenylketonuria. In this study, an adsorbent prepared from corn cobs was evaluated for the removal of tyr...
Article
Full-text available
The performance of carbons produced from the cold-pressed cake of Raphanus sativus (L. var.), a residue from the biodiesel industry, was evaluated for the adsorption of methylene blue (MB) from synthetic aqueous solutions. The study has focused on the following three topics: (i) physical and textural characterization of the carbon, (ii) batch inves...
Article
a b s t r a c t Phenylalanine removal is a necessary step for production of protein hydrolysates appropriate for consumption by phenylketonuria patients. In this study, the feasibility of employing an agricultural residue as precursor material in the production of adsorbents for phenylalanine removal from model solutions was studied. The adsorbent...
Article
a b s t r a c t The objective of this work was to evaluate the potential of Fourier transform infrared spectroscopy (FTIR) for the discrimination of defective and non-defective coffee beans. Defective (black, immature and sour) and non-defective Arabica coffee beans were submitted to FTIR analysis by transmittance readings employing KBr discs and r...