José Miguel Aguilera

Caking phenomena in amorphous food powders

Abstract Caking of free-flowing powders during storage is a deleterious phenomenon that is ubiquitous in the feed, fertilizer and pharmaceutical industries, and of economical importance for low-moisture foods. Among other subjects related to caking of amorphous powders, the following aspects are reviewed in this article: (1) physical and morphological changes, and quantitative procedures to assess caking; (2) proposed mechanisms of caking phenomena; (3) examples of caking in food materials; (4) the relationships between storage-induced caking and other phenomena and the glass transition of amorphous powders; (5) methods for estimating the evolution of caking with time from the physical properties of powder samples and environmental conditions; and (6) measures to minimize the occurrence of caking phenomena.

Description of food surfaces and microstructural changes using fractal image texture analysis

Images, particularly photomicrographs, provide qualitative information about surfaces of foods and cells. Methods to analyze the texture of images such as fractional Brownian motion (FBMM), box counting (BCM), and fractal dimension (FD) estimation from frequency domain (FDM), were used to numerically describe the surfaces of foods and the microstructure of potato cells. A FD was calculated for each image using the power-law scaling for self-similar fractals. The surface of analyzed foods had FD varying from 2.22 for chocolate to 2.44 for pumpkin shell. As reference, the FD of sandpaper having increasing grain size or roughness varied from 2.37 to 2.65. FD was also useful to numerically describe microstructural changes with time of an isolated potato cell during heating in oil and of the surface of chocolate undergoing crystallization of fats (blooming).

Food dehydration and product structure

Abstract Dehydration of biological material is a controlled effort to preserve the structure or create a new one that serves for functional purposes. In this context, food dehydration is revisited from the perspective of recent advances in food materials science, knowledge from desiccation in Nature, microstructural probing, novel processing technologies and deeper insights into drying mechanisms, among others. The role of structure in dehydrated products appears evident to understand transport mechanisms and to design functional properties. Some approaches and research topics in structure of dehydrated products are presented and discussed.

Engineering and food for the 21st century

VISION Food Engineering for the 21st Century, D. B. Lund Trends in Food Engineering, G. Trystram and J.J. Bimbenet Challenges for the Process Specialist in the 21st Century, K.R. Swartzel Sustainability of Food Sector Development in Tropical Areas, A.L. Raoult-Wack and N. Bricas International Congress on Engineering and Food: The First 25 Years, R. Jowitt PHYSICAL CHEMISTRY State Transitions and Reaction Rates in Concentrated Food Systems, Y. H. Roos and S. M. Lievonen Biopolymer-Biopolymer Interactions at Interfaces and their Impact on Food Colloid Stability, S. Damodaran Triacylglyceride Crystallization in Vegetable Oils, J. F. Toro-Vazquez, E. Dibildox-Alvarado, V. Herrera-Coronado and M. Charo-Alonso The Functionality of Milkfat Fractions in Confectionery and Plastic Fats, A. G. Marangoni Stabilization Mechanisms for Anthocyanin: The Case for Copolymerization Reactions, P. Wesche-Ebeling and A. Argaiz-Jamet MASS TRANSFER Transport Properties in Food Engineering, G. D. Saravacos Mass Transfer and Related Phenomena in Plant Tissue during Heat Treatment and Osmotic Stress, W. Spiess, D. Behsnilian, M. Ferrando, M. Gaiser, U. Gartner, M. Hasch, E. Mayer-Miebach, A. Rathjen, and E. Walz Non-Fickian of Mass Transfer in Fruit Tissue, V. Gekas, F. Oliveira, and G. Crapiste The Cellular Approach in Modeling Mass Transfer in Fruit Tissues, M. Le Maguer, G. Mazzanti, and C. Fernandez Mass Transport and Deformation Relaxation Phenomena in Plant Tissues, P. Fito, A. Chiralt, J. M. Barat and J. Martinez-Monzo The Relation Between Sublimation Rate and Volatile Retention during the Freeze-Drying of Coffee, K. Niranjan, J. M. Pardo, and D. S. Mottram A Proposal of Analysis of the Drying Phenomena by Means of the Fractal Theory, G. F. Gutierrez-Lopez, J. Chanona-Perez, L. Alamilla-Beltran, A. Hernandez-Parada, A. Jimenez-Aparicio, R. Farrera-Rebollo, and C. Odorica-Vargas FOOD RHEOLOGY Relationship Between Rheology and Food Texture, M. C. Bourne Relevance of Rheological Properties in Food Process Engineering, J. Velez-Ruiz Rheological Properties of Concentrated Suspensions: Applications to Foodstuffs, P. J. Carreau, F. Cotton, G. P. Citerne, and M. Moan Mixing of Viscoelastic Fluids: A New Strategy to Elucidate the Influence of Elasticity on Power Consumption, E. Brito-De la Fuente, F. Bertrand, P. Carreau, and P.A. Tanguy Microstructuring of Multiphase Food Systems in Shear and Elongational Process Flows, E. J. Windhab, P. Fischer, M. Stranzinger, and S. Kaufmann Modeling Viscosity of Starch Dispersion and Dough during Heating: Master Curves of Complex Viscosity, J. Tattiyakul, H-L. Liao, and M.A. Rao The Role of Rheology in Extrusion, O. H. Campanella, P. X. Li, K. A. Ross, and M. R. Okos Non-Linear Viscoelasticity Modeling of Vegetable Protein-Stabilized Emulsions, C. Gallegos, J. M. Franco, J. M. Madiedo, A. Raymundo, and I. Sousa Rheological Properties of Food Materials Under Standard and High Pressure and Temperature Conditions, A. Gaspar-Rosas Rheo-Reactor for Studying Food Processes: Specific Cases of Foaming and Freezing, L. Choplin, B. E. Chavez-Montes, and E. Schaer FOOD STRUCTURE Levels of Structure and the Mechanical Properties of Solid Foods, M. Peleg Structure-Functionality Relationships in Foods, A. H. Barret Structure and Food Engineering, J.M. Aguilera Viewing Food Microstructure, J. C. G. Blonk THERMAL PROCESSING AND PACKAGING Active Packaging: Science and Application, M. L. Rooney Mass Transfer in Food/Plastic Packaging Systems, R. Gavara and R. Catala Mass Transport within Edible and Biodegradable Protein Based Materials: Application to the Design of Active Biopackaging, S. Guilbert, A. Redl, and N. Gontard Cooling Uniformity in Overpressure Retorts Using Water Spray and Full Immersion, M. A. Tung, G. F. Morello, A. T. Paulson, and I. J. Britt Contribution to Kinetics for the Development of Food Sterilization Processes at High Temperatures: IATA-CSIC Results, M. Rodrigo, A. Martinez, and C. Rodrigo MINIMAL PROCESSING Shelf-Life Prediction of Minimally Processed Chilled Foods, B. M. McKenna Update on Hurdle Technology, L. Leistner Microbial Behavior Modeling as a Tool in the Design and Control of Minimally Processed Foods, S. M. Alzamora and A. Lopez-Malo The Role of an Osmotic Step: Combined Processes to Improve Quality and Control Functional Properties in Fruits and Vegetables, D. Torreggiani and G. Bertolo Approaches for Safety Assessment of Minimally Processed Fruits and Vegetables, M. S. Tapia and J. Welti-Chanes EMERGING TECHNOLOGIES Membrane Permeabilization and Inactivation Mechanisms of Biological Systems by Emerging Technologies, D. Knorr, V. Heinz, A. Angersbach, and D-U. Lee Innovative Fruit Preservation Methods using High Pressure, E. Palou, A. Lopez-Malo, and J. Welti-Chanes Production Issues Related to UHP Food, E. Y. Ting and R. G. Marshall Enhanced Thermal Effects Under Microwave Heating Conditions, H. S. Ramaswamy, T. Koutchma, and S. Tajchakavit Applications of Low Intensity Ultrasonics in the Dairy Industry, A. Mulet, J. A. Carcel, J. Benedito, and N. Sanjuan Ohmic Heating and Moderate Electric Field (MEF) Processing, S. K. Sastry, A. Yousef, H-Y. Cho, R. Unal, S. Salengke, W-C. Wang, M. Lima, S. Kulshrestha, P. Wongsa-Ngasri, and I. Sensoy Design, Construction and Evaluation of a Sanitary Pilot Plant System (PEF), Q. H. Zhang, C. B. Streaker, Jr., and H. W. Yeom PROCESS CONTROL Recent Advances in Simulation for the Process Industries, D. Bogle Simulation-Based Design of Food Products and Processes, A.K. Datta Modeling and Simulation of Reactive and Separation Food Bed Processes, F. Lopez-Isunza, E. S. Perez-Cisneros, and S. I Flores y De Hoyos Modeling Bean Heating during Batch Roasting of Coffee Beans, H. G. Schwartzberg FOOD BIOTECHNOLOGY New Frontiers for Food Processing: The Impact of Changes in Agrobiotechnology, R. Quintero-Ramirez Novel and Potential Applications of alpha-Amylases in the Food Industry, G. Saab-Rincon, G. Del Rio, R. I. Santamaria, M. L. Diaz, X. Soberon, and A. Lopez-Munguia Modelling Conditions Affecting the Production of a Bacteriocin by Enterococcus faecium UQ1 and the Kinetics of the Bacteriocin Antilisterial Activity, B. Garcia-Almendarez, J. Ibarra-Silva, L. Mayorga-Martinez, J. Dominguez-Dominguez, and C. Regalado ENVIRONMENTAL Clean Technology in the Food Manufacturing Industry, P. J. Lillford and M. F. Edwards Pest Control in the Food Industry: Raw Materials Control, P. Valle-Vega SPACE MISSIONS Storage Stability and Nutritive Value of Food for Long-Term Manned Space Missions, D. Zasypkin and T-C. Lee Preservation Methods Utilized for Space Food, Y. Vodovotz and C. T. Bourland NASA Food Technology Commercial Space Center, D. G. Olson EDUCATION Role of the Internet in Food Engineering Teaching, R. P. Singh Teaching Food Engineering with the Aid of Multmedia, M. Lopez-Leiva A Low-Cost, Versatile Laboratory Experiment in Food Engineering Using the Internet, F. Courtois and R. P. Singh Toward a Virtual Cooperative Training Program in Food Engineering, E. Parada-Arias, G. F. Guterrez-Lopez, and C. Odorica-Vargas

Glass transitions and shrinkage during drying and storage of osmosed apple pieces

Abstract The relationship between shrinkage during drying and ‘glass’–‘rubber’ transitions of apple tissue was studied. Our results did not indicate that structural collapse of apple pieces can be reduced by diminishing the difference Δ T between drying temperature and glass transition temperature ( T g ) of the fruit matrix. Apple shrinkage was not consistently depressed by reducing drying temperature, infusing larger amounts of T g -depressing agents (sucrose, maltose, lactose) or infusing similar amounts of solutes with higher anhydrous T g s. However, sugars added during osmotic dehydration pretreatments help decreasing structural collapse during subsequent air drying, which was reflected by a 20–65% increase in final volume of samples treated with 50% sucrose and maltose solutions as compared to an air-dried, control sample. Dried samples remained in the “rubbery” state after drying and shrunk during subsequent storage.

New dimensions in microstructure of food products

Abstract Food microstructure is the organization of elements within a food and their interaction. Food scientists break down and build up microstructure during food processing, which should be viewed as a series of restructuring and reassembling operations. Researchers in this field have benefited from newer techniques available for examining food microstructure and analyzing images. Microstructural knowledge is critical if food properties are to be controlled properly since there is a causal connection between structure and functionality. The microstructural approach to food processing and engineering is based on the realization that microstructural changes underlie product properties and microstructural techniques are necessary to understand structure-property relationships.

Structure and Texture Properties of Fried Potato Products

Potatoes are the fourth most important vegetable crop in the world, and in 2003, it was a 2.7 billion dollar business in the US alone. Nearly one-third of the potato production is processed into par-fried frozen potatoes and fried chips (snacks). Frying imparts desirable taste and textural properties to these products, the latter described usually by the sensorial term crispness. Frying is reviewed as a structuring process, and methodologies to determine texture in fried potato products are discussed. It is demonstrated that the histological and microstructural heterogeneity of potato tubers have hampered clear interpretation of experimental data and a rigorous modeling of frying. Moisture uptake during post-frying is critical in the loss of crispness (limpness) of fries and in softening of potato chips. Methods to evaluate these changes and alternatives to prolong the shelf life are discussed.

Glassy state and thermal inactivation of invertase and lactase in dried amorphous matrices

The thermal stability of enzymes lactase and invertase in dried, amorphous matrices of sugars (trehalose, maltose, lactose, sucrose, raffinose) and some other selected systems (casein, PVP, milk) was studied. The glass transition temperature (Tg) was limited as a threshold parameter for predicting enzyme inactivation because (a) enzyme inactivation was observed in glassy matrices, (b) a specific effect of enzyme stabilization by certain matrices particularly trehalose was observed, and (c) enzyme stability appeared to depend on heating temperature (T) “per se” rather than (T − Tg) . For these reasons, a protective mechanism by sugars related to the maintenance of the tertiary structure of the enzyme was favored. A rapid loss of enzyme (lactase) activity was observed in heated sucrose systems at T > Tg, and this was attributed to sucrose crystallization since it is known that upon crystallization the protective effect of sugars is lost. Thus, the stabilizing effect could be indirectly affected by the Tg of the matrix, since crystallization of sugars only occurs above Tg. Trehalose model systems (with added invertase) showed an exceptional stability toward “darkening” (e.g., non‐enzymatic browning) when heated in the dried state to elevated temperatures and for long periods of time.

Drying and Dried Products Under the Microscope

Food engineers do not often realise that drying of foods and biological materials is a problem of preserving or transforming structures rather than one of removing water. Some unique product properties depend on the structure of dried foods: rehydration and instant properties, flavour retention and sensorial attributes (including colour and texture). The role of structure extends in biochemical and pharmaceutical products to the molecular level and plays key role in viability of desiccated plants and organisms and/or specific activity of dried biomolecules. Nowadays different techniques and probes are available to visualise changes in structure down to the nanostructural level, acquire physicochemical data of micron-size regions and perform physical/mechanical testing in situ. Most novel visualisation methods are non-intrusive permitting image and data acquisition in real time under simulated or current drying conditions. An emerging field of work is that of quantification of structural features using advanced image processing techniques and fractal analysis. Meaningful structure-properties relationships of dried foods can then be derived from their analysis that might contribute to the design of new and specific structures to improve food functionality. Combination of the microstructural approach and concepts from food materials science should result in major advances in this important unit operation and in tailoring product properties.

Revision: Extracción con CO2 a alta presión. Fundamentos y aplicaciones en la industria de alimentos / Review: High pressure CO2 extraction. Fundamentals and applications in the food industry

Supercritical extraction (SFE) is a unit operation that exploits the dissolving power of supercritical fluids (SF) under conditions above their critical temperature and pressure. It is possible to obtain solvent-free extracts using SF and the extraction is faster than using conventional organic solvents. These advantages are due to the high volatility of SF (gases under normal environmental conditions) and improved transport properties (i.e., high diffusivity and low viscosity). When using carbon diox ide (CO,) in particular, moderate-temperature processing and high selectivity towards valuable microconstituents in natural products can be achieved. This article presents a review of transport properties and solubilities in SF, particularly CO2, as well as other underlying factors that are respon sible for the kinetics and phase equilibrium in SFE processes. It also describes the selective CO 2 ex traction of essential oils, pungent principles, carotenoid pigments, antioxidants, antimicrobials, and related substances to be used as ingredients for the food, drug and perfume industries, from spices, herbs and other plant materials. These very important applications are discussed from the point of view of the potential applications of SFE in Latin America. The two most important commercial ap plications of SFE in the food industry, namely hop extraction and coffee decaffeination, are reviewed to a limited extent. Some other potential applications briefly described include extraction and frac tionation of edible fats and oils, purification of solid matrices, and concentration of fermentation broths, fruit juices and other extracts. In most cases CO2 extracts are compared with counterparts obtained using conventional methods.