Complex Food Systems Research Articles

Flow‐through imaging cytometry for characterization of Salmonella subpopulations in alfalfa sprouts, a complex food system

We recently developed an approach combining fluorescence in situ hybridization (FISH) and flow cytometry for detecting low levels of Salmonella spp. (approximately 10(3) cells/mL sprout wash) against high levels of naturally occurring sprout flora (approximately 10(7)-10(8) CFU/g sprouts). Although this "FISH and flow" approach provided rapid presence/absence testing for Salmonella in this complex food system, it was not capable of more nuanced tasks, such as probing the phenotypic complexity of the microbes present in sprouts or determining the physical interactions of Salmonella with these microbes, or with sprout debris. In the present study, we have combined rapid FISH-based labeling of Salmonella spp. in sprout washes with flow-through imaging cytometry (FT-IC), using the ImageStream 100, a commercial FT-IC instrument. This approach enables image-based characterization of various subpopulations of interest occurring within these samples. Here, we demonstrate the ability of FT-IC to unambiguously identify cells, cell aggregates and other events within these subpopulations based on both cell morphology and hybridization status after reaction with a Salmonella-targeted probe cocktail. Our ability to directly explore the nature of these events expands the layers of information possible from cytometric analyses of these complex samples and clearly demonstrates that "a picture is worth a thousand dots".

Potential of Raman Spectroscopy and Imaging Methods for Rapid and Routine Screening of the Presence of Melamine in Animal Feed and Foods

The impact of melamine-contaminated animal feed ingredients on food safety has become a major public concern ever since melamine was identified as the organic compound responsible for the deaths of a significant number of cats and dogs in 2007 by way of adulterated pet food. Melamine, a common industrial chemical often added to resins to improve flame resistance and proposed as an alternative form of fertilizer-N for plant growth, was found to be intentionally added to animal feed in amounts ranging from 0.2% to 8% of total mass as a way to boost the products’ apparent protein content. It was also used as a binder in the production of pelleted feed for animals. In addition to melamine, a small amount of cyanuric acid, ammeline, and ammelide were also detected in pet feed and in the tissues and urine of dead pets that had consumed the contaminated food. Even though it is possible that cyanuric acid, ammeline, and ammelide were added, their presence more likely resulted from the degraded derivatives of melamine. There is a great concern that melamine will again enter the food chain and be consumed by humans and animals. As part of the Food Protection Plan, US federal agencies such as the FDA and FSIS and other organizations have established GCMS and LC-MS/MS procedures for the analysis of melamine in food/feed commodities. Although they can detect melamine contaminants in trace amount, these time-consuming laboratory procedures require chemical solvents for the extraction steps and depend on expensive mass spectrometry. Rapid, nondestructive, and routine methods for the specific detection of melamine in raw feed materials are increasingly important, not only for public health concerns but also for melamine screening to prevent protein fraud. Undoubtedly, the well-defined mass spectroscopic technique is preferred due to its low detection limit and capability for structural elucidation; however, since adulteration of raw materials by melamine usually occurs in higher concentrations in order to affect protein content, the high sensitivity of the mass spectroscopic technique may not be necessary. In addition, mass spectrometry might not be sufficiently rapid to screen for the presence of melamine in a large number of food/feed materials from very different sources, because the identification process includes sample-specific extraction procedures, which are labor-intensive and time-consuming. Fast melamine screening requires minimal sample preparation (e.g., no extraction or centrifugation), routine analysis of a number of samples without reagents, minimal procedural steps, and easy operation and interpretation of results. The Raman technique, which has been used to obtain structural information on melamine, is an alternative approach that can be applied to solid materials with no sample pretreatment. In addition, the use of the Fourier transform (FT) methodology and a 1064 nm excitation laser in the near-infrared (NIR) region provides precise wavenumber measurement and good-quality Raman spectra by reducing the interference from fluorescence and photodecomposition of colorants present in food and feed. Raman studies of melamine and melamine-modified resins have been reported in the literature, and the results have revealed the feasibility of the Raman technique for the structural characterization of melamine state in resins. However, there have been few reports on Raman investigation and identification of melamine in complex food and feed systems. The objectives of this study were (1) to identify the characteristic Raman bands in melamine-contaminated wheat flour, corn gluten, and soybean meal mixtures; and (2) to develop simple and universal ratio algorithms for qualitative and quantitative analysis of melamine in mixtures. The ultimate goal is to develop both Raman spectroscopy and Raman chemical imaging methods for rapid, accurate, nondestructive, specific, and routine screening of the presence of melamine in food and feed for public/animal safety and security.

Factors influencing the calorimetric determination of glass transition temperature in foods: A case study using chicken and mutton

Glass transition temperature (Tg) of complex food systems like chicken and mutton depends on several factors. Hence the reported values of Tg for these food systems varied from sample to sample. Present study was an attempt to investigate various parameters such as annealing temperature and time employed, moisture content of the sample, rate of heating during DSC scan etc. affecting the calorimetric determination of Tg. Varying one parameter at a time and by keeping all others constant, the influence of these parameters on Tg, were investigated. As annealing temperature decreased from −11 °C to −23 °C, Tg values for chicken and mutton shifted towards lower temperatures. Similarly annealing time up to 1 h also significantly influenced Tg values. Initial moisture content of the meat samples was also found to influence Tg values. Rate of heating employed during the DSC analysis, played a vital role in the Tg determination. This study delineated the effect of these parameters on glass transition temperature and helped in optimizing DSC protocol for calorimetric determination of Tg for chicken and mutton samples.

Impact of Olfaction on Taste, Trigeminal, and Texture Perceptions

Research on perceptual interactions has mainly been conducted on olfaction and taste. Few studies have extended the investigation to trigeminal and texture perceptions. The objective of the study was to explore systematical interactions between olfaction, taste, texture, and trigeminal perceptions with a specific focus on the role of olfaction. Ingredients inducing olfactory (odorant), taste (citric acid), and trigeminal (cooling agent) perceptions were systematically varied in a viscous model system. A panel assessed sensory properties of the products within the same odorant type under two different conditions: with and without noseclip. Olfaction strongly influenced taste and trigeminal perceptions but also modulated perceptual taste/taste and taste/trigeminal interactions. But results involving texture perception were inconclusive since the evaluation condition (with and without wearing a noseclip) might have impacted mastication and swallowing behaviors. These findings highlight the multiplicity and overlapping of olfactory/trigeminal/taste perceptual interactions in complex food systems.

Food Anoxia and the Formation of Either Flavor or Toxic Compounds by Amino Acid Degradation Initiated by Oxidized Lipids

Amino acid degradation plays an important role in the formation of both flavors and toxic compounds during food processing. These reactions are produced, to a significant extent, as a consequence of the Maillard reaction among amino acids and carbohydrates. However, recent studies have shown that lipids also take part in these reactions. This article reviews the current knowledge of the contribution of lipids to both flavor and toxic-compound formation by amino acid degradation, describing the formation of Strecker aldehydes and the conversion of amino acids into their vinylogous derivatives as a consequence of lipid-amino acid reactions. Current data suggest that amino acids can be converted into either Strecker aldehydes or vinylogous derivatives by many lipid derivatives, which exhibit diverse reactivities for both reactions. Reaction conditions, including the presence of oxygen, also play a major role in the Strecker aldehyde/vinylogous derivative ratio obtained. Nevertheless, the high number of lipid derivatives involved, the different alternative pathways, and the existence of both positive and negative synergisms between lipids and carbohydrates make it hard to predict the effect of reaction conditions in the Strecker aldehyde/vinylogous derivative ratio obtained in complex food systems.

Delivery of Functionality in Complex Food Systems: Physically Inspired Approaches from Nanoscale to Microscale

The purpose of this Delivery of Functionality in Complex Food Systems symposium was to develop a fundamental understanding of the rational design principles required to create high-quality and healthy foods. The symposium highlighted the need for a multidisciplinary and integrated approach to rational food design, involving physicists, chemists, biologists, food technologists, physiologists, sensory scientists, psychologists, chefs, and social scientists. The conference moved from a consideration of the characteristics and interactions of basic food components to the nanoscopic and microscopic structures created by assembly of these basic components, to the bulk physicochemical and sensory properties of foods, to the interaction of foods with the mouth and gastrointestinal tract, and finally, to the scientific basis of fine cuisine (molecular gastronomy).

Enhancing Personal Agency and Competence in Eating and Moving: Formative Evaluation of a Middle School Curriculum—Choice, Control, and Change

The purpose of this formative evaluation was to examine the impact of an innovative inquiry-based science education curriculum for middle school students, called Choice, Control, and Change, that is designed to foster healthful eating and physical activity and a healthy weight through enhancing agency and competence. The 24-session curriculum helps students develop understandings about the interactions between biology, personal behavior, and the environment and personal agency through cognitive self-regulation skills in navigating today’s complex food system and sedentary environment. An extended theory of planned behavior served as the design framework. The study used a pretest-posttest evaluation design involving 278 middle school students in 19 science classes within 5 schools. Based on paired t tests, students significantly improved on several curriculum-specific eating and physical activity behaviors: they decreased several sedentary activities and increased their frequencies of fruit and vegetable intake. They decreased the frequency of sweetened beverages, packaged snacks, and eating at a fast-food restaurant, and ate and drank smaller portions of some items. Their outcome beliefs and overall self-efficacy, but not their attitudes, became more positive. A strategy based on fostering personal agency, cognitive self-regulation, and competence can be effective in increasing healthful eating and physical activity behaviors in middle school children and should be explored further.

Rheology and phase behavior of aggregating emulsions related to droplet-droplet interactions

The present work deals with the relationship between colloidal interactions and physical properties of emulsions, in particular rheology and gel transition. Experimental data on protein-stabilized oil-in-water emulsions are considered. In this system, the excess of protein in the aqueous phase yields reversible droplet aggregation by the mechanism of depletion. Thus both phase and flow behaviors can be controlled by changing protein concentration, ionic strength and temperature. Calculations of the potential of interaction between droplets are carried out in the framework of colloid science. Particular emphasis is placed on the role that droplet-droplet interaction plays in defining the morphology of the aggregates, hence the microstructure and finally, the bulk physical properties. This understanding offers new perspectives in the study of complex food systems.

Equilibrium and non-equilibrium structures in complex food systems

The physics ruling the macroscopic behaviour of foods is discussed in a few selected examples in which the equilibrium/non-equilibrium nature can be directly related to the typical length scale of the food structure and the specific interaction strength, the latter describing the decrease in specific free energy (e.g., per mole of species or per single event) when going from a non-equilibrium to the equilibrium configuration. Liquid-crystalline phases in foods, such as those based on self-assembled lipids and water, are discussed as an example of equilibrium system, in which low correlation length scales (∼nm) enable very-short times to re-organize molecules into equilibrium configurations. High internal phase emulsions and dry foams where length scales are very large (∼10 1–10 4 μm), are discussed as a typical example of non-equilibrium system, which however, can be stable for long times owing to the high free energy barrier and the large correlation lengths. Finally double emulsion systems are considered as an example where both interaction strength and correlation lengths have intermediate values. This allows tuning morphologies and making equilibrium behaviour to prevail over non-equilibrium by suitably tailoring the energetic interactions. In particular the case of osmotic pressure in the water phase of water/oil/water double emulsions is discussed as a viable route to control interaction strength in complex food systems.

The Online Professional Master of Science in Food Safety Degree Program at Michigan State University: An Innovative Graduate Education in Food Safety

A market-research study conducted in 2000 indicated a need for a degree program in food safety that would cover all aspects of the food system, from production to consumption. Despite this, such a program was not enthusiastically supported by employers, who feared losing their valued employees while they were enrolled in traditional on-campus graduate programs. A terminal professional degree was successfully created, offered, and modified over the succeeding five years. The innovative, non-traditional online program was developed to include a core curriculum and leadership training, with elective courses providing flexibility in specific areas of student interest or need. The resulting Professional Master of Science in Food Safety degree program provides a transdisciplinary approach for the protection of an increasingly complex food system and the improvement of public health. Enrollment in the program steadily increased in the first three years of delivery, with particular interest from industry and government employees. The curriculum provides a platform of subject material from which certificate programs, short-courses, seminars, workshops, and executive training programs may be delivered, not only to veterinarians but also to related food and health specialists. The program has fulfilled a need for adult learners to continue as working professionals in the workforce. The benefit to the employer and to society is an individual with enhanced knowledge and networking and leadership skills.

Delivery of functionality in complex food systems: introduction

Delivery of functionality in complex food systems: introduction

EFFECT OF SPICES ON GROWTH AND SURVIVAL OF SALMONELLA TYPHIMURIUM DT 104 IN GROUND BEEF STORED AT 4 AND 8C

ABSTRACT Few studies have addressed the use of spices against pathogens associated with meat. The effects of garlic, ginger and turmeric were evaluated against Salmonella Typhimurium DT 104 that were inoculated either in spice paste or in buffered peptone water (BPW) or in heat‐treated ground beef and stored at 4 and 8C for 10 days. Data from the spice pastes study showed a decrease in Salmonella Typhimurium DT 104 counts, and the greatest reduction (3.39 log) was observed in garlic paste stored at 4C. Garlic in BPW data showed a reduction of 1.5 and 1.0 log in Salmonella Typhimurium counts at 4 and 8C, respectively. Ground beef stored at 4C showed no growth or a slight reduction in growth in samples with spice, while all samples at 8C showed an increase in Salmonella Typhimurium counts. Results show that the spices inhibit or inactivate Salmonella Typhimurium DT 104 when they are in direct contact. However, when spices are added to a complex food system such as ground beef, the inhibitory activity of these spices considerably decreases.

A techno-managerial approach in food quality management research

In this article it is discussed that food quality management issues are much more complex than often assumed and that it requires a specific research approach. It is argued that food quality management deals with dynamic and complex food systems and people systems involved in realising food quality. A conceptual food quality relationship is developed, assuming that food quality is a function of both food and human behaviour and their interaction. The relationship reflects that food quality is dependent on both dynamic properties of the food product, as related to applied technological conditions, and dynamic properties of people, as related to applied administrative conditions. A techno-managerial approach to research food quality management issues is derived, which involves the integrated analysis of theories from technological and managerial sciences.

Surface enhanced laser desorptions ionization-time of flight-mass spectrometry analysis in complex food and biological systems

Molecular Nutrition & Food ResearchVolume 49, Issue 12 p. 1104-1111 Education Surface enhanced laser desorptions ionization-time of flight-mass spectrometry analysis in complex food and biological systems Harshadrai M. Rawel, Harshadrai M. Rawel rawel@rz.uni-potsdam.de Search for more papers by this authorSascha Rohn, Sascha Rohn Technical University of Berlin, Institute of Food Technology and Food Chemistry, Department of Food Analysis, TIB 4/3-1, Berlin, GermanySearch for more papers by this authorJürgen Kroll, Jürgen Kroll University of Potsdam, Institute of Nutritional Science, Department of Physiology and Pathophysiology, Potsdam, Germany. Fax: +49-33200-88-541Search for more papers by this authorFlorian J. Schweigert, Florian J. Schweigert University of Potsdam, Institute of Nutritional Science, Department of Physiology and Pathophysiology, Potsdam, Germany. Fax: +49-33200-88-541Search for more papers by this author Harshadrai M. Rawel, Harshadrai M. Rawel rawel@rz.uni-potsdam.de Search for more papers by this authorSascha Rohn, Sascha Rohn Technical University of Berlin, Institute of Food Technology and Food Chemistry, Department of Food Analysis, TIB 4/3-1, Berlin, GermanySearch for more papers by this authorJürgen Kroll, Jürgen Kroll University of Potsdam, Institute of Nutritional Science, Department of Physiology and Pathophysiology, Potsdam, Germany. Fax: +49-33200-88-541Search for more papers by this authorFlorian J. Schweigert, Florian J. Schweigert University of Potsdam, Institute of Nutritional Science, Department of Physiology and Pathophysiology, Potsdam, Germany. Fax: +49-33200-88-541Search for more papers by this author First published: 21 November 2005 https://doi.org/10.1002/mnfr.200500047Citations: 15AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume49, Issue12December 2005Pages 1104-1111 RelatedInformation

Sustainable Agriculture in the UK

Most agricultural assessments of global environmental change made to date have not focused explicitly on sustainability issues, and have neglected the considerable impacts of shifting agricultural zones, alterations in commercial fertiliser and pesticide use, and changes in the demand for water resources. The current crisis in agriculture, with its economic, political, social and ecological dimensions, has arisen because of the pursuit of a productivity technology/policy model. This broad policy of agricultural ‘modernisation’ and development through the application of agricultural science and technology has shaped the direction of technological change in agriculture and the evolution of a complex agro-industrial food system.1 This paper focuses on England’s Rural Development Programme2 as it contributes to sustainable agriculture alongside the control of pollution.

Unambiguous Identification of Volatile Organic Compounds by Proton-Transfer Reaction Mass Spectrometry Coupled with GC/MS

Interest in on-line measurements of volatile organic compounds (VOCs) is increasing, as sensitive, compact, and affordable direct inlet mass spectrometers are becoming available. Proton-transfer reaction mass spectrometry (PTR-MS) distinguishes itself by its high sensitivity (low ppt range), high time resolution (200 ms), little ionization-induced fragmentation, and ionization efficiency independent of the compound to be analyzed. Yet, PTR-MS has a shortcoming. It is a one-dimensional technique that characterizes compounds only via their mass, which is not sufficient for positive identification. Here, we introduce a technical and analytical extension of PTR-MS, which removes this shortcoming, while preserving its salient and unique features. Combining separation of VOCs by gas chromatography (GC) with simultaneous and parallel detection of the GC effluent by PTR-MS and electron impact MS, an unambiguous interpretation of complex PTR-MS spectra becomes feasible. This novel development is discussed on the basis of characteristic performance parameters, such as resolution, linear range, and detection limit. The recently developed drift tube with a reduced reaction volume is crucial to exploit the full potential of the setup. We illustrate the performance of the novel setup by analyzing a complex food system.

Performance on an odor detection and identification test as a predictor of ortho- and retronasal odor intensity ratings in the young and elderly

Two experiments were conducted to examine whether performance on the European Test of Olfactory Capabilities (ETOC, 16 odors to be detected and identified) can predict ortho- and retronasal odor intensity ratings. In Experiment 1 (Exp1), vanilla (0–0.31%) in a beverage (whey drink) was rated for ortho- and retronasal intensity and the ETOC was performed by elderly ( n = 27, 66–83, mean 74.4 years) and young ( n = 32, 22–36, mean 26.0 years). In Experiment 2 (Exp2), 17 elderly (67–84, mean 74.9 years) and 10 young (22–29, mean 25.9 years) performed the ETOC and rated varying concentrations of vanilla and lemon in aqueous solutions, grape juice and yogurt for ortho- and retronasal intensity. For the young, the mean detection/identification scores of the ETOC were 15.8/14.0 (Exp1), and 15.6/13.2 (Exp2). The corresponding scores for the elderly were 14.6/10.6 (Exp1) and 13.0/7.9 (Exp2). Orthonasally, the young differentiated the aroma concentrations in the whey drinks better than the elderly performing poorly in ETOC. Retronasally, the young and the well performing elderly gave higher intensity ratings for higher concentrations, while the poorly performing elderly were unable to do this. A tendency for small intensity difference in the poorly performing elderly was observed in ortho- and retronasal ratings for aqueous solutions, and orthonasal ratings for grape juice and yogurt. Retronasal intensity ratings of the elderly for grape juice and yogurt were not associated with their ETOC performance. Hence, olfactory performance measured by the ETOC predicted orthonasal intensity ratings, though not evidently, while its predictive ability for the retronasal intensity ratings of the elderly for complex food systems was deficient.

Influence of amylose-flavor complexation on build-up and breakdown of starch structures in aqueous food model systems

Starch, in particular the linear amylose, is able to form inclusion complexes with a wide variety of flavor compounds. Build-up and breakdown of starch/flavor structures in aqueous food model systems were followed with iodometric titration, oscillatory measurements, light microscopy and differential scanning calorimetry (DSC). Amylose-flavor complexation promotes gelation and spherulitic crystallization in simple starch dispersions as well as in complex food systems including milk proteins and sugars. Crystalline starch/flavor spherulites and amylose-flavor complexes are very slowly attacked by α-amylase in mouth while fast breakdown of amylose-flavor complexes becomes possible in the gastrointestinal tract. It is concluded that starch/flavor interactions influence the sensory properties of starch based food systems in particular texture quality and flavor release. Amylose-flavor complexation might be an encapsulation principle for food where a controlled flavor release is desired.

Food process engineering and dairy technology at the Technical University of Munich

The Chair for Food Process Engineering and Dairy Technology at the Technical University of Munich in Freising‐Weihenstephan has been installed since 1992 in a new building hosting modern and well‐equipped laboratories and pilot‐plant facilities. Its objectives in terms of research are to participate in the development of the scientific understanding of complex food systems and their constitutive components, and the way they interact with the process during manufacturing. The aim is to allow the production of food products with desired properties, improved quality and optimal safety, while ensuring an efficient use of raw materials and of the energy required for industrial production. The methodology used involves the fractionation of complex systems and the systematic study of their constitutive components taken in isolation as well as in various combinations. Milk, as a naturally complex raw material, receives particular attention, but research activities increasingly extend to other functional food substrates such as eggs. The research activities are organized into three working groups that reflect the core competencies developed at the chair throughout the years: Bio‐Processes and Aseptic Processing, Formation of Structures in Food Systems, and Protein Technology. Its key position within the ‘Centre of Life and Food Science’ of the Technical University of Munich fosters interdisciplinary interactions with many specialized scientists, and therefore provides a broad perspective regarding the comprehension of the complex implications of modern food and pharmaceutical product manufacturing.

Validation of a polynomial regression model: the thermal inactivation of Bacillus subtilis spores in milk.

The predicted survival of Bacillus subtilis 168 spores from a polynomial regression equation was validated in milk. Bias factor suggested as an index of model performance was used to validate the polynomial model predictions in ultrahigh temperature (UHT) treated and sterilized whole and skim milk. Model predictions were fail safe, predicting higher D-values (decimal reduction times) in buffer than actually noted in milk. The D-values for spores were lower in milk as compared with those predicted in potassium phosphate buffer contrary to the popular expectation of better spore survival in complex food systems. The Bias factor, a quantitative measure of the model performance, indicated that on average the model predictions exceed the observations by 40% in the case of whole milk and by 60% in the case of skim milk. The present work is an attempt to ascertain the extent of reliability that one can safely place in polynomial model predictions, without compromising on the safety or palatability of foods where it is eventually intended to be applied. The work has also highlighted the differences in the thermal inactivation pattern of spores in buffer and in milk with a possible influence of the various constituents of milk. The work will assist the dairy industry to better design thermal processes to ensure longer shelf life of dairy foods.