Seddik Khalloufi

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• Doctor of Philosophy
• Professor at Université Laval

Abstract The production of soy milk and tofu may or may not involve a hulling step, generating two distinct by-products: okara from dehulled soybeans (okara㊀SH) and non-dehulled soybeans (okara㊉SH), which retain soy hulls (SH). The main objective of this study was to investigate the compositional and functional differences between these by-products...

The agro-food supply chain generates significant quantities of waste and byproducts globally, influenced by regional socioeconomic conditions, policy frameworks, and environmental concerns. The soybean industry generates various byproducts during the production processes of oil, soy milk, tofu, soy yogurt, edamame, miso, tempeh, natto, and soy sauc...

Due to environmental concerns and economic value, the adsorption process using agricultural wastes is one of the promising methods to remove lead (Pb) from contaminated water. The relationships between agricultural waste properties, adsorption conditions, and the maximum Pb adsorption capacity of selected adsorbents have not been adequately explore...

The necessity of identifying and quantifying sugars in food processing is endless for maintaining food quality attributes such as color, taste, texture, monitoring regulatory compliance, labeling packages, and maintaining authenticity. Despite available analytical methods for characterizing sugar molecules, the limitations of conventional methods d...

Monosaccharides such as glucose, fructose, and galactose are the building blocks of oligosaccharides and act as the major energy sources in our body. These three monosaccharides are the most prominent in food processing and widely consumed analytes, found in fruits or milk. Although several analytical methods are available to identify and quantify...

The environmental release of heavy metals presents significant threats to human health and ecosystems, necessitating the development of effective remediation strategies. Biosorption has emerged as an eco-friendly and cost-effective method for the removal of heavy metals from contaminated water. In this study, the potential of fava husk (FH), lentil...

The necessity of identifying and quantifying sugars in food processing is endless for maintaining food quality attributes such as color, taste, and texture, monitoring regulatory compliance, labeling packages, and maintaining authenticity. Despite available analytical methods for characterizing sugar molecules, the limitations of conventional metho...

Food dehydration, the process of reducing moisture in food to improve shelf life, is one of the oldest food preservation methods used by the food processing industry. During dehydration, the porous structure within foods undergoes various alterations, significantly impacting both process efficiency and consumer acceptance. The types of pores, namel...

The contribution of dehydration to the growing market of food powders from slurry/liquid matrices is inevitable. To overcome the challenges posed by conventional drying technologies, several innovative approaches have emerged. However, industrial implementation is limited due to insufficient information on the best‐suited drying technologies for ta...

Osmotic dehydration (OD) is an efficient preservation technology in that water is removed by immersing the food in a solution with a higher concentration of solutes. The application of OD in food processing offers more benefits than conventional drying technologies. Notably, OD can effectively remove a significant amount of water without a phase ch...

Bulk density is among the fundamental properties for defining quality attributes of dehydrated foods. Mathematical models offer elegant tools for predicting bulk density and therefore optimizing dehydration processes. In this contribution, three machine learning techniques, namely extreme learning machine (ELM), support vector machine (SVM), and ev...

As consumers become more aware of their health and environment, food manufacturers have begun to incorporate more sustainable nutritional ingredients into their products. Agricultural wastes present a well-established source of highly nutritive and functional ingredients, such as dietary fibers (DF). In order to promote the use of agro-waste DFs as...

Heavy metal contamination in wastewater is a significant concern for human health and the environment, prompting increased efforts to develop efficient and sustainable removal methods. Despite significant efforts in the last few decades, further research initiatives remain vital to comprehensively address the long-term performance and practical sca...

Dietary fiber (DF) significantly affects the quality attributes of food matrices. Depending on its chemical composition, molecular structure, and degree of hydration, the behavior of DF may differ. Numerous reports confirm that incorporating DF derived from food waste into food products has significant effects on textural, sensory, rheological, and...

Background Agro-food production processes generate a significant amount of waste, causing a serious environmental burden and a loss of revenue for industry. However, plant food wastes are rich in dietary fibers (DF). These complex carbohydrates offer a variety of human health benefits, including the ability to bind toxic heavy metals like arsenic,...

Mobilization of heavy metals in the environment has been a matter of concern for several decades due to their toxicity for humans, environments, and other living organisms. In recent years, use of inexpensive and abundantly available biosorbents generated from fibrous plant-based food-waste materials to remove heavy metals has garnered considerable...

Chemical interaction and multicompound competition were investigated on solids gain and carbohydrate profiles evolution during osmotic dehydration of mangoes. Tommy Atkins mango slices (0.4 cm and 1.5 cm thickness) were osmotically processed at 40°C for up to 4 h and 8 h, respectively. Osmotic solutions (60 °Brix) were separated in two categories:...

A significant amount of waste is annually generated worldwide by the supply chain of the food industry. Considering the population growth, the environmental concerns, and the economic opportunities, waste recovery is a promising solution to produce valuable and innovative ingredients for food and nonfood industries. Indeed, plant‐based wastes are r...

Osmotic dehydration kinetics depends on food tissue microstructure; thus, modulation of mango porosity could help selectively enhance water removal over sugar gain. In this present study, pretreatments of freeze-thawing (freezing at −36 °C for 2 weeks and thawing at 4 °C for 24 h) and pulsed electric field (1 kV/cm, 10 and 30 pulse numbers), were a...

Shrinkage and collapse phenomena are the two mechanisms involved in the evolution of pores within food products during dehydration. These phenomena can be mathematically represented by shrinkage and collapse functions, which can be derived from theoretical models of porosity, bulk density, or volume reduction coefficient. In this contribution, thes...

Plant food wastes generated through the food chain have attracted increasing attention over the last few years not only due to critical environmental and economic issues but also as an available source of valuable components such as dietary fibers. However, the exploitation of plant waste remains limited due to the lack of appropriate processing te...

Plant food wastes generated through the food chain have attracted increasing attention over the last few years not only due to critical environmental and economic issues but also as an available source of valuable components such as dietary fibers. However, the exploitation of plant waste remains limited due to the lack of appropriate processing te...

Pore formation efficiency can be defined as the volume of pores formed and/or remained vs. the maximum volume of pores that could have been formed and/or remained during processing. This contribution proposes new mathematical tools to estimate four different and complementary types of pore formation efficiencies, named here the overall efficiency,...

Every year, agrifood activities generate a large amount of plant byproducts, which have a low economical value. However, the valorization of these byproducts can contribute to increasing the intake of dietary fibers and reducing the environmental pollution. This review presents an overview of a wide variety of agricultural wastes applied in the for...

Porosity is generally used to monitor the evolution of pore formation during dehydration. However, in some cases of dehydration, porosity could increase without involving pore formation, resulting in misleading interpretation. To avoid this misleading interpretation, this contribution suggests a new concept, which is the normalized air content (NAC...

In the last years, there is a growing concern about food waste due to economic and substantial environmental impacts. According to the hierarchy management framework, recycling has been proposed as the proper sustainable approach to turn waste materials into profitable products. Among food wastes, agricultural waste products with the most contribut...

Osmotic dehydration of mangoes was investigated for the reduction of solids gain (SG) and potential use of natural syrups as osmotic solutions. Different osmotic solutions at 60 °Brix were used (made with sucrose, glucose, fructose, corn syrup solids (CSS), and agave syrup (AS) with or without added xanthan gum [XG] or inulin) during osmotic dehydr...

Moisture profiles evolution of a cellular food product (potato) and two non-cellular food models made with maltodextrins (DE19 and DE36) were investigated during air-drying at two different temperatures, 25°C and 55°C. MRI results of suggested a non-uniform moisture distribution within potato, whilst the non-cellular food models had a more uniform...

Cellular and non-cellular-solid food systems were used to obtain experimental data of aw and Tg as a function of moisture content during drying. Guggenheim-Anderson-de Boer (GAB), Flory-Huggins, Gordon-Taylor, and Khalloufi-Ratti models were assessed in order to obtain the state diagrams of Potato, carrot and two types of water-agar-maltodextrin mo...

Cellular and non-cellular-solid food systems were used to obtain experimental data of aw and Tg as a function of moisture content during drying. GAB, Gordon-Taylor, and Khalloufi-Ratti models were used to obtain the state diagrams of the four food systems investigated. The results suggest that the GAB and Khalloufi-Ratti models can successfully be...

In the present work, the impact of glass transition on shrinkage of non-cellular food systems (NCFS) during air-drying will be assessed from experimental data and the interpretation of a ‘shrinkage’ function involved in a mathematical model. Two NCFS made from a mixture of water/maltodextrin/agar (w/w/w: 1/0.15/0.015) were created out of maltodextr...

Infusion of antioxidants into vegetables is a new food strategy managed by matrix processing. Raw and blanched apple were air or freeze dried. In the case of freeze-dried samples, different freezing methods were previously applied: conventional (−28°C), blast freezing (−30 °C) and liquid N2(−196°C). Afterwards, air and freeze-dried samples at the d...

The effects of total protein/total solid ratio (TP/TS) and pH on the spray drying process and rehydration properties of soy powder were investigated. The results showed that a decrease in the pH of the feed from 7 to 4 resulted in an increase of particle size, wettability index (WI), dispersibility index (DI) and water content (WC) of soy powder. I...

X-ray microtomography (micro-CT) was used to quantify the density, porosity and shrinkage during air drying of carrots and eggplants (aubergine). This study demonstrates the capability of micro-CT to visualise and analyse the 3D microstructure of vegetables during air drying. The density, porosity and shrinkage could be analysed from the 3D micro-C...

Several experimental methods for measuring porosity, bulk density and volume reduction during drying of foodstuff are available. These methods include among others geometric dimension, volume displacement, mercury porosimeter, micro-CT, and NMR. However, data on their accuracy, sensitivity, and appropriateness are scarce. This paper reviews these e...

In this paper we have analyzed the hydration properties of vegetable materials, namely carrots and mushrooms, by means of the Flory-Rehner theory. This is done to circumvent problems with the ill-defined concept of water holding capacity. Via this thermodynamic theory one can predict the hydration properties for a wide range of mechanical loads. Th...

The aim of this study was to elucidate the factors affecting the dispersibility and morphology of soy powders. The influences of the configuration of a spraying system (CSS) on particle size and dispersibility of soy powders were investigated. The dispersibility, morphology, and particle sizes of powders produced using a wheel and those obtained us...

There are many challenges and problems in food science and magnetic resonance methods may be used to provide answers and deepen both fundamental and practical knowledge. This book presents the latest innovations in magnetic resonance and in particular new applications to understanding the functionality of foods, their processing and stability and t...

Although drying is one of the oldest approaches that have been used by humans to preserve foods, this technology is still an active scientific topic for researchers in both industry and academia. Indeed, during drying processes, food products undergo several physical, chemical, and structural changes which have a direct impact on the quality of the...

Several empirical/theoretical models are available in the open literature to predict the volume shrinkage coefficient (Sv). However, the few reported theoretical models do not consider the variation of the porosity as a function of water content during drying. In this contribution, a theoretical model was used to describe Sv as a function of water...

The aim of this study was to gain insights into the factors affecting the dispersibility of soy powder. The influences of the total solid/total protein (TS/TP) ratio, dextrose equivalent (DE) of maltodextrins (MD) and spray drying system configuration (wheel or nozzle) on particle sizes and dispersibility of soy powders were investigated. The dispe...

For thermo-sensitive food products, supercritical-carbon-dioxide (SC-CO2) drying process could be a promising technology. The process takes place in three steps: (i) removal of water from the food matrixes, (ii) adsorption of the water removed in the adsorber bed, and (iii) regeneration of the adsorber with hot air. In this investigation, a mathema...

The pore formation during drying is controlled by two mechanisms which are represented by two functions. These functions are expected to be universal, thus recurrent and applicable to relevant physical properties of the products during drying. This contribution aims at studying the sensitivity of shrinkage and collapse functions in predicting the p...

Volume change is one a fundamental aspect in characterization of drying processes. Several attempts to simulate the volume change during drying have been reported in the open literature. However, so far no theoretical approach has been used to support these simulations, especially when it comes to dealing with the springback effect. In this contrib...

Drying assisted by supercritical carbon dioxide is foreseen to become a promising technology for sensitive food products. In this contribution, a mathematical model is derived to describe the changes in water concentration in both a solid food matrix and a fluid carrier during drying. Finite different element method is used to solve the set of mass...

Although several empirical models are available in the literature to predict density in solid matrices, only a very limited number of theoretical models have been reported. So far, no model considered the possible variation in the initial air volume existing at the beginning of the drying process. In this contribution, a theoretical model to predic...

In this contribution, a mathematical model is built to predict the changes in water concentration in both a solid food matrix and a fluid carrier during supercritical carbon dioxide (SC–CO2) drying. The mass balance equations of the model involve five dimensionless parameters: Peclet number modified Sherwood number, Fourier number, mass ratio and e...

Several models have been reported to predict the porosity during drying. However, currently these models do not allow quantifying the possible evolution of the initial air volume existing at the beginning of the drying process. In this study, a theoretical model was built to predict the porosity of dried materials by taking into account the possibl...

This paper reviews the effects of the addition of flaxseed gum on the physicochemical properties of whey protein-stabilized, oil-in-water emulsions at neutral and acidic pH as investigated by light scattering and rheology under dilute and concentrated conditions. At pH 7.0, measurements performed in the dilute system showed no changes in charge or...

The effect of the addition of flaxseed gum on the physicochemical properties of whey protein-stabilized (WPI) oil-in-water emulsions at pH 3.5 was investigated. Two different varieties (Emerson and McDuff) were tested at concentrations ranging from 0% to 0.33% (w/v), by measuring droplet size, ζ-potential, phase separation behavior, microstructure...

Concentrations ranging from 0% to 0.33% (w/v) of gum (Emerson and McDuff) were added to the emulsions at pH 7. Particle size distribution, viscosity, ζ-potential, microstructure, and phase separation kinetics of the emulsions were observed. Both polysaccharides and protein coated droplets are negatively charged at this pH, as shown by ζ-potential m...

Diffusing wave spectroscopy (DWS) was used to investigate the behavior of flaxseed gums when added to WPI-stabilized emulsions. The effect of different concentrations (0-0.33% (w/v)) of flaxseed gum, derived from two seed varieties, namely Emerson and McDuff, was studied at acidic and neutral pH. At pH 7.0 and low gum concentrations the dynamic and...

This article presents a mathematical model describing the unsteady heat and mass transfer during the freeze drying of biological materials. The model was built from the mass and energy balances in the dried and frozen regions of the material undergoing freeze drying. A set of coupled nonlinear partial differential equations permitted the descriptio...

ABSTRACT Several quality parameters, such as volumetric shrinkage, internal structure, color changes, and glass transition temperature (Tg) of dry solids, were investigated during freeze-drying of strawberry, apple, and pear, at various combinations of freezing and freeze-drying temperatures. Process conditions had different impacts on the quality...

Glass transition temperature (Tg) has been identified as a critical factor to predict quality of foodstuffs during processing or storage. Differential Scanning Calorimetry (DSC) was used to determine the Tg of 4 types of berry powders as a function of water content, and equilibrium moisture content was measured over different saturated solutions uu...

Sorption isotherms at 4, 13, and 27°C were obtained for two types of berries (strawberries and blueberries) and three types of commercial and wild mushrooms (Shiitake Lentinus edodes, Enoki Flammulina velutipes and Morel Morchella esculenta). The products had been freeze-dried for 72 h and equilibrated over saturated salt solutions in a range of re...

This paper presents a numerical investigation of the sorption kinetics under constant-pressure conditions using a finned adorption reactor. The governing equations, derived from local thermodynamic equilibrium and energy balance, are solved using an explicit scheme. The model is validated and used to analyze the effect of important design parameter...

This paper presents a theoretical and experimental analysis of a constant pressure adsorption process. The governing heat and mass transfer equations derived from local thermodynamic equilibrium and energy balance are solved numerically. The model is validated by comparison with experimental results. It is then used to analyze the effect of some op...

The supercritical-carbon-dioxide (Sc-CO 2) drying process could be a promising technology for sensitive food products. The use and applicability of this technology to foodstuff drying is still under investigation with very limited available data. In this contribution, a mathematical model is derived to describe the changes in water concentration in...

In the area of drying, simulations techniques are often used to optimize the process parameters and operation conditions. The credibility and the validity of these simulations depend, among others, on the values of the physical parameters involved in the development of the models. Porosity is one of those physical parameters required to perform suc...

Thèse (Ph. D.)--Université Laval, 2001. Bibliogr.