Formation of pores and bubbles and their impacts on the quality attributes of processed foods: A review.

Pores and bubbles significantly influence the physical attributes (like texture, density, and structural integrity), organoleptic properties, and shelf life of processed foods. Hence, the quality of foods and their acceptance by the consumers could be influenced by the properties and prevalence of pores and bubbles within the food structure. Considering the importance of pores, this review aimed to comprehensively discuss the factors and mechanisms involved in the generation of pores and bubbles during the processing of different food products. Moreover, the characteristics and effects of pores on the properties of chocolates, cheeses, cereal-based foods (like cake, puffed grains, and pasta), dried, and fried products were discussed. The impacts of bubbles on the quality of foam-based products, foam creamers, and beverages were also explored. This review concludes that intrinsic factors (like food compositions, initial moisture content, and porosity) and extrinsic factors (like applied technologies, processing, and storage conditions) affect various properties of the pores and bubbles including their number, size, orientation, and distribution. These factors collectively shape the overall structure and quality of processed food products such as density, texture (hardness, cohesiveness, chewiness), and water holding capacity. The desirability or undesirability of pores and their characteristics depends on the type of products; hence, some practical hints were provided to mitigate their adverse effects or to enhance their formation in foods. For example, pores could increase the nutrient digestion and reduce the shelf life of the products by enhancing the risk of fat oxidation and microbial growth. In conclusion, this study provides a valuable resource for food scientists and industry professionals by discussing the effects of pores on food preservation, heat, and mass transfer (including oxygen, moisture, flavors, and nutrients). Understanding the dynamic changes in porosity during processing will be effective in customization of final product quality with desired attributes, ensuring tailored outcomes for specific applications.

Review of osmotic dehydration: Promising technologies for enhancing products' attributes, opportunities, and challenges for the food industries.

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 change, which reduces the energy demand associated with latent heat and high temperatures. A specific feature of OD is its ability to introduce solutes from the hypertonic solution into the food matrix, thereby influencing the attributes of the final product. This review comprehensively discusses the fundamental principles governing OD, emphasizing the role of chemical potential differences as the driving force behind the molecular diffusion occurring between the food and the osmotic solution. The kinetics of OD are described using mathematical models and the Biot number. The critical factors essential for optimizing OD efficiency are discussed, including product characteristics, osmotic solution properties, and process conditions. In addition, several promising technologies are introduced to enhance OD performance, such as coating, skin treatments, freeze-thawing, ultrasound, high hydrostatic pressure, centrifugation, and pulsed electric field. Reusing osmotic solutions to produce innovative products offers an opportunity to reduce food wastes. This review explores the prospects of valorizing food wastes from various food industries when formulating osmotic solutions for enhancing the quality and nutritional value of osmotically dehydrated foods while mitigating environmental impacts.

Exploring conventional and emerging dehydration technologies for slurry/liquid food matrices and their impact on porosity of powders: A comprehensive review.

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 targeted products. Therefore, this review aimed to compare various conventional and emerging dehydration technologies (such as active freeze, supercritical, agitated thin-film, and vortex chamber drying) based on their fundamental principles, potential applications, and limitations. Additionally, this article reviewed the effects of drying technologies on porosity, which greatly influence the solubility, rehydration, and stability of powder. The comparison between different drying technologies enables informed decision-making in selecting the appropriate one. It was found that active freeze drying is effective in producing free-flowing powders, unlike conventional freeze drying. Vortex chamber drying could be considered a viable alternative to spray drying, requiring a compact chamber than the large tower needed for spray drying. Freeze-dried, spray freeze-dried, and foam mat-dried powders exhibit higher porosity than spray-dried ones, whereas supercritical drying produces nano-porous interconnected powders. Notably, several factors like glass transition temperature, drying technologies, particle aggregation, agglomeration, and sintering impact powder porosity. However, some binders, such as maltodextrin, sucrose, and lactose, could be applied in controlled agglomeration to enhance powder porosity. Further investigation on the effect of emerging technologies on powder properties and their commercial feasibility is required to discover their potential in liquid drying. Moreover, utilizing clean-label drying ingredients like dietary fibers, derived from agricultural waste, presents promising opportunities.

A review on the hydration properties of dietary fibers derived from food waste and their interactions with other ingredients: opportunities and challenges for their application in the food industry.

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 antimicrobial properties. Additionally, the characteristics of DF, modification techniques (chemical, enzymatic, mechanical, thermal), and processing conditions (temperature, pH, ionic strength), as well as the presence of other components, can profoundly affect the functionalities of DF. This review aims to describe the interactions between DF and water, focusing on the effects of free water, freezing-bound water, and unfreezing-bound water on the hydration capacity of both soluble and insoluble DF. The review also explores how the structural, functional, and environmental properties of DF contribute to its hydration capacity. It becomes evident that the interactions between DF and water, and their effects on the rheological properties of food matrices, are complex and multifaceted subjects, offering both opportunities and challenges for further exploration. Utilizing DF extracted from food waste exhibits promise as a sustainable and viable strategy for the food industry to create nutritious and high-value-added products, while concurrently reducing reliance on primary virgin resources.

Valorization of Fibrous Plant-Based Food Waste as Biosorbents for Remediation of Heavy Metals from Wastewater-A Review.

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 research attention. The aim of this review is to investigate the applicability of using fibrous plant-based food waste, which comprises different components such as pectin, hemicellulose, cellulose, and lignin, to remove heavy metals from wastewater. This contribution confirms that plant-fiber-based food waste has the potential to bind heavy metals from wastewater and aqueous solutions. The binding capacities of these biosorbents vary depending on the source, chemical structure, type of metal, modification technology applied, and process conditions used to improve functionalities. This review concludes with a discussion of arguments and prospects, as well as future research directions, to support valorization of fibrous plant-based food waste as an efficient and promising strategy for water purification.

Hornification: Lessons learned from the wood industry for attenuating this phenomenon in plant-based dietary fibers from food wastes.

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 rich in dietary fibers (DF), which have relevant technical functionalities such as water/oil holding capacity, swelling capacity, viscosity, texture, and physiological properties such as antioxidant activity, cholesterol, and glucose adsorption capacities. Different drying technologies could be applied to extend the shelf life of fresh DF. However, inappropriate drying technologies or process conditions could adversely affect the functionalities of DF via the hornification phenomenon. Hornification is related to the formation of irreversible hydrogen bindings, van der Waals interactions, and covalent lactone bridges between cellulose fibrils during drying. This review aims to capitalize on the knowledge developed in the wood industry to tackle the hornification phenomenon occurring in the food industry. The mechanisms and the parameters affecting hornification as well as the mitigation strategies used in the wood industry that could be successfully applied to foods are summarized. The application of conventional drying technologies such as air or spray-drying increased the occurrence of hornification. In contrast, solvent exchange, supercritical drying, freeze-drying, and spray-freeze-drying approaches were considered effective strategies to limit the consequences of this phenomenon. In addition, incorporating capping agents before drying attenuated the hornification. The knowledge summarized in this review can be used as a basis for process design in the valorization of plant-based wastes and the production of functional DF that present relevant features for the food and packaging industries.

Sugar profiles modulation of mangoes during osmotic dehydration in agave syrup solutions.

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: single solute (sucrose, glucose, fructose) and multisolute (agave syrup, alone or with additions of 5% inulin or 0.1-0.3% xanthan gum) solutions. High performance liquid chromatography (HPLC) analysis was carried out on treated mango to determine sugar profiles evolution during osmotic dehydration and final product concentrations. Findings pointed out that composition of osmotic solution may modulate mango sugar profiles by triggering uptake or loss of sugar according to different phenomena: chemical potential gradient, lixiviation, prevailing mass transfer, formation of carbohydrate barrier, and solution viscosity. Mango was enriched with the solute present in the single solute osmotic solution, while it lost its own native sugars, which were absent in the osmotic solution. Increasing sample thickness reduces individual sugar uptake or loss in mango treated with both single and multisolute solutions. Significant differences in mono solute solution behavior were found for sucrose due to its capability to form a sugar layer outside the surface of thicker samples, which was shown by scanning electron microscopy (SEM) images, a barrier markedly hindering the sucrose uptake or loss. Addition of polysaccharides (particularly xanthan gum) was found to have an impact of lowering mango individual sugar uptake (18-30%). Practical Application These results will help in understanding the mechanisms by which gain of individual sugars could be reduced and composition could be modulated during osmotic dehydration of fruits. Thus, the findings in this work could lead to production of low-sugar content, osmotically processed mango snacks, enriched with inulin, enhancing their dietary and marketable value.

A mapping approach to assess the evolution of pores during dehydration.

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, these two functions were simplified to capture four extreme scenarios of dehydration, which consist in the combination of total or no shrinkage with total or no collapse. The four simplified equations were used to generate theoretical maps characterized by three distinct zones that are associated with pore evolution. Each of these zones represents a key dehydration situation. By superimposing experimental data of porosity, bulk density, or volume reduction coefficient on these theoretical maps, it is possible to assess dehydration processes, i.e., drying technologies and/or dehydration conditions, in terms of pore formation and evolution over time. These theoretical maps can be constructed for each food product before starting the dehydration processes. Therefore, when the experimental data is available, the suggested mapping approach is a simple, fast, and reliable tool to: (i) assess the performance of a given dehydration process versus specific cases of pore formation, and (ii) compare different dehydration processes in terms of their ability to promote pore formation. This practical tool can be used by the industry and academia to quantitatively evaluate how far a drying technology and/or its dehydration conditions are from the ideal scenario in terms of pore formation. This gap quantification will provide a basis for converging towards the ideal scenario by fine-tuning the dehydration conditions or choosing the appropriate drying technology.

Pulsed Electric Field and Freeze-Thawing Pretreatments for Sugar Uptake Modulation during Osmotic Dehydration of Mango.

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 applied to mango 1 cm-thickness slices prior to osmotic dehydration conducted at 40 °C for 4 h. Three different 60 °Brix agave syrup solutions with or without added polysaccharides (inulin or xanthan gum) were used in the osmotic dehydration operation. Water loss (WL), sugar gain (SG) and microstructure images were used to compare the effects of pretreatments on mango osmotic dehydration efficiency. Results indicated that pulsed electric field (PEF) pretreatment increased slightly WL during osmotic dehydration, contrary to freeze-thawing (F-T), which for most cases led to a decrease. As for solids uptake, due to higher damage induced by F-T to mango tissue, SG was higher than for fresh and PEF pretreated mangoes. Using xanthan gum as additive to agave syrup solution, helped to decrease sugar uptake in frozen-thawed mango due to an increase in solution viscosity. A similar WL/SG ratio was obtained with frozen-thawed mango in solution with xanthan gum. Therefore, in the case of frozen-thawed mango, it is recommended to use an osmotic solution with high viscosity to obtain low sugar uptake in the final product. The novelty of this contribution is twofold: (i) using pretreatments (F-T or PEF) to minimize sugar uptake during osmotic dehydration, and (ii) using agave syrup with added polysaccharides to enrich final product with inulin.

The applications of conventional and innovative mechanical technologies to tailor structural and functional features of dietary fibers from plant wastes: A review.

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 technologies to recover and tailor fiber functionalities. Among the different technologies developed for waste valorization, mechanical techniques were suggested to be a promising and sustainable strategy to extract fibers with improved functionalities. In this context, the present review describes different mechanical technologies (conventional and innovative) with potential applications to produce micro/nanofibers from various plant residues, highlighting the operating principle as well as the main advantages and pitfalls. The impact on the structural, technological, and functional properties of fibrous materials is comprehensively discussed. The extent of fiber modification not only highly depended on the technology and operation conditions used but also on fiber composition and the application of posttreatments such as dehydration. Other variables, including economic and environmental issues such as equipment cost, energy demand, and eco-friendly features, are also reviewed. The outputs of this review can be used by both the industrial sector and academia to select a suitable combination of fiber and processing technology for designing novel foods with improved functionalities that fulfill market trends and consumer needs.

Natural plant fibers obtained from agricultural residue used as an ingredient in food matrixes or packaging materials: A review.

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 formulation of different food products and sustainable packaging. In general, the incorporation of fibers into bakery, meat, and dairy products was successful, especially at a level of 10% or less. Fibers from a variety of crops improved the consistency, texture, and stability of sauce formulations without affecting sensory quality. In addition, fiber fortification (0.01-6.4%) presented considerable advantages in terms of rheology, texture, melting behavior, and fat replacement of ice cream, but in some cases had a negative impact on color and mouthfeel. In the case of beverages, promising effects on texture, viscosity, stability, and appetite control were obtained by the addition of soluble dietary fibers from grains and fruits with small particle size. Biocomposites used in packaging benefited from reinforcing effects of various plant fiber sources, but the extent of modification depended on the matrix type, fiber pretreatment, and concentration. The information synthesized in this contribution can be used as a tool to screen and select the most promising fiber source, fiber concentration, and pretreatment for specific food applications and sustainable packaging.

Shrinkage and porosity evolution during air-drying of non-cellular food systems: Experimental data versus mathematical modelling.

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 maltodextrins with dextrose equivalent 19 (MD19) or 36 (MD36). The NCFS made with MD19 had 30°C higher Tg than those with MD36. This information indicated that, during drying, the NCFS with MD19 would pass from rubbery to glassy state sooner than NCFS MD36, for which glass transition only happens close to the end of drying. For the two NCFS, porosity and volume reduction as a function of moisture content were captured with high accuracy when represented by the mathematical models previously developed. No significant differences in porosity and in maximum shrinkage between both samples during drying were observed. As well, no change in the slope of the shrinkage curve as a function of moisture content was perceived. These results indicate that glass transition alone is not a determinant factor in changes of porosity or volume during air-drying.

Interactions between flaxseed gums and WPI-stabilized emulsion droplets assessed in situ using diffusing wave spectroscopy.

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 spatial characteristics of the system remained unchanged. While at gum concentrations from 0.075% to 0.20% a rapid phase separation was observed, at higher concentrations phase separation was retarded because of the increased background viscosity slowing down the mobility of the emulsion droplets. At pH 3.5, the difference in overall electrical charge between the gum (negative) and the protein on the emulsion surface (positive) led to electrostatic interactions. While at low concentration of flaxseed gum the general characteristics of the emulsions were not significantly different, at intermediate concentrations, bridging flocculation occurred. When sufficient flaxseed gum was present, the emulsion droplets mobility was arrested in a gel-like state. In spite of the compositional differences in the ratio of acidic and neutral fraction between the two polysaccharides extracted from different seed varieties, at both values of pH the behavior of the emulsions after addition of the polysaccharide was comparable.