Food Engineering Reviews最新文献

The olive oil industry has been operating for centuries, but in the last decades, significant attention has gone to the development of physical technologies that enhance the traditional extra virgin olive oil (EVOO) extraction process efficiency. Studies have validated such technologies at industrial scale in medium-sized olive oil factories. These physical technological interventions are aimed to achieve at least one of the following outcomes: (a) higher EVOO throughput by implementing a continuous uniform-heating process alternative to semi-batch malaxation, (b) increase the recovery of EVOO, and (c) enhance the phenolic content in olive oil. The present work identifies the status of what is presently achievable with these physical interventions. A systematic comparison across recent studies was conducted in factories processing beyond 1 T h⁻¹ olive paste. Technologies used in these studies include heat exchangers, microwaves (MW), ultrasound (US), megasonics (MS), and pulsed electric fields (PEF) individually or in combination.

Graphical Abstract

Evaporators are one of the most important equipment in the food process industries such as sugar, fruit juices, dairy products, edible oils, tomato paste, and coffee. They need a lot of energy in the form of steam from boiler and it is necessary to minimize their energy consumption. One of the best strategies for this purpose is the design and application of multiple-effect evaporators (MEEs), in which the vapor from one stage (effect) is the heating medium for the next stage. There are various configurations and designs for MEEs and they can also be equipped with vapor compression systems and steam ejectors to further reduce the energy consumption and increase their economic efficiency. This article is covering the fundamentals, design, simulation, control, and application of MEEs in various food industries for the first time with discussing recent advances in this field.

Graphical Abstract

The annual global amount of water consumed to produce food ranges from 600,000 to 2.5 million liters per capita depending on food habits and food waste generation. Humans need approximately 2–3 L of water daily to maintain health, but only 0.01% of the world’s water is drinkable. Food supplies cannot be generated without land, water, and energy use. The current use of water for production of food is most concerning and requires immediate and increased awareness. Minimal attention has been devoted to the increasing water scarcity and loss of drinking water. Food waste also contains water and therefore also adds to water scarcity that is affecting almost 4 billion people. We summarize the human need of water, its significance for life and for the production, processing, and consumption of foods. This review includes an examination of the history of water; the unique properties of water for sustaining life; water for food production including agriculture, horticulture, and mariculture; the properties of water exploited in food processing; water scarcity due to water demands exceeding availability or access; and its consequences for our world. Means to reduce water scarcity, including using water treatment and promoting change of human habits, are discussed. The future of water and the recommendations for action are proposed for decreasing water scarcity and reducing water use during food production, food processing, food preparation, and consumption.

Fruit juices are traditionally processed thermally to avoid microorganisms’ growth and increase their shelf-life. The concentration of juices by thermal evaporation is carried out to reduce their volume and consequently the storage and transportation costs. However, many studies revealed that the high-temperature operation destroys many valuable nutrients and the aroma of the juice. Currently, membrane technology has emerged as an alternative to conventional processes to clarify and concentrate fruit juices due to its ability to improve juices’ safety, quality, and nutritional values. Low-cost, low-energy requirement, and minimal footprint make membrane technology an attractive choice for industrial adoption. The low-temperature operation that preserves the nutritional and sensorial quality of the juice can fulfill the market demand for healthy juice products. In this review, the pressure-driven membrane processes, including microfiltration, ultrafiltration, and reverse osmosis; osmotic distillation; membrane distillation; and forward osmosis that have been widely investigated in recent years, are discussed.

Traditionally, the effect of temperature on the rate of biochemical reactions and biological processes in foods, and on the mechanical properties of biopolymers including foods, has been described by the Arrhenius equation which has a single adjustable parameter, namely the “energy of activation.” During the last three decades, this model has been frequently replaced by the WLF equation, borrowed from Polymer Science, which has two adjustable parameters and hence better fit to experimental data. It is demonstrated that the WLF model (and hence also the VTF model) is identical to an expanded version of the Arrhenius equation where the absolute temperature is replaced by an adjustable reference temperature. Both versions imply that the curve describing a process or reaction’s rate rise with temperature or the viscosity or modulus drop with temperature must have the same characteristic upper concavity above and below the glass transition temperature, T_g, however it is defined and determined. Nevertheless, at least some reported experimental data recorded at or around the transition regime suggest otherwise and in certain cases even show concavity direction inversion. The mathematical description of such relationships requires different kinds of temperature-dependence models, and two such alternatives are described. Also suggested are two different ways to present the temperature as a dimensionless independent variable which enables to lump and compare different transition patterns in the same graph. The described approach is purely formalistic; no fit considerations are invoked and neither model is claimed to be exclusive.

The application of hurdle interventions can improve microbial efficacy as well as ensure food quality. Light-emitting diodes (LEDs), as a promising non-thermal food preservation technology, have increasingly attracted attention in the food industry; however, the technology possesses certain limitations that have impeded widespread adoption by the food industry. In recent years, the combination of LEDs with other intervention strategies (e.g., exogenous photosensitizers, traditional, and novel approaches) has been proposed and attracted much interest. This review aims to provide a comprehensive summary of the current status of LED-based hurdle technologies in the food industry. The review focused on the combined effect and mechanism of different hurdles and LEDs in improving food safety. In addition, the potential as a pre-treatment tool for LEDs was also evaluated for their ability to reduce microbial resistance to other interventions. Finally, some critical issues and challenges have been proposed to be addressed to ensure the efficacy and safety of LED-based hurdles in food systems.

For many high-pressure processes employing pressurized fluids, such as supercritical fluid extraction (SFE) of natural matrices with supercritical carbon dioxide (scCO₂), CO₂ plays a central role as a solvent, solubilizing agent, or medium for extracting and processing diverse food-type substances, in which the knowledge on the solubility behavior of multiple compounds at the varying process conditions is essential in the process design, but not completely understood. High-pressure solubility data in pure scCO₂ or cosolvent-modified CO₂ of distinct types of organic compounds found in or related to food (mainly vegetable oils, essential oils, carotenoids, phenolics, and vitamins) published in the last decade were reviewed, encompassing temperatures of 298–373 K and pressures up to 95 MPa. Crossover phenomena, solubility enhancements in cosolvent systems or those containing a co-solute, and the antisolvent feature of CO₂ are also discussed. Current models for the correlation of solubility data by semi-empirical and thermodynamic models are compared, and the limitations of each class of models are highlighted. Lipid-soluble substances (fatty acid esters, fatty acids, and essential oils) are the most CO₂-soluble food-type substances in contrast to polar and complex polyphenols and carotenoids. The investigated solutes can be obtained by SFE, separated by fractionation using scCO₂, or applied to enzymatic reactions and particle formation processes. It was concluded based on recent applications that improved SFE, effective separation factors for supercritical fractionation, better solubilization of reactive systems, and supersaturation conditions to obtain micronized particles could be established based on the solubility behavior of dissolved solutes in the supercritical media at high pressures.

Food packaging materials are crucial to maintaining food quality, as they play an important role in preventing food deterioration, dehydration, and oxidation. Unlike synthetic polymers, natural biopolymers, such as polysaccharides and proteins, are abundant and widespread resources that are nontoxic, biocompatible, and biodegradable. In food packaging, contact between packaging materials and moist foods can frequently degrade the performance of the materials. This has increased research into the development of hydrophobic biopolymer-based films. Here, we summarize the effective preparation strategies, mechanical and barrier properties, pH responsiveness, self-cleaning performance, and antibacterial and antioxidant functions of hydrophobic biopolymer-based films. The most effective methods for preparing hydrophobic biopolymer-based films are electrospinning with hydrophobically modified biopolymers, adding micro/nanofillers and hydrophobic compounds to the films, and hydrophobically modifying the films. These methods can even generate superhydrophobic films with excellent barrier properties. We also discuss the current opportunities and challenges presented by hydrophobic biopolymer-based films.

Capillary pressure plays a critical role in driving fluid flow in unsaturated porous (pores not saturated with liquids but also containing air/gas) structures. The role and importance of capillary pressure have been well documented in geological and soil sciences but remain largely unexplored in the food literature. Available mathematical models for unsaturated food systems have either ignored the capillary-driven flow or combined it with the diffusive flow. Such approaches are bound to impact the accuracy of models. The derivation of the microscale definition of capillary pressure is overviewed, and the limitations of using the microscale definition at the macroscale are discussed. Next, the factors affecting capillary pressure are briefly reviewed. The parametric expressions for capillary pressure as a function of saturation and temperature, developed originally for soils, are listed, and their application for food systems is encouraged. Capillary pressure estimation methods used for food systems are then discussed. Next, the different mathematical formulations for food systems are compared, and the limitations of each formulation are discussed. Additionally, examples of hybrid mixture theory–based multiscale models for frying involving capillary pressure are provided. Capillary-driven liquid flow plays an important role in the unsaturated transport during the processing of porous solid foods. However, measuring capillary pressure in food systems is challenging because of the soft nature of foods. As a result, there is a lack of available capillary pressure data for food systems which has hampered the development of mechanistic models. Nevertheless, providing a fundamental understanding of capillary pressure will aid food engineers in designing new experimental studies and developing mechanistic models for unsaturated processes.