Investigations on the Diffusion Behavior of Smoke-Associated Aroma Compounds into the Sausage Matrix as Affected by Casing, Caliber, and Packaging.

The aim of the study was to investigate how smoke-associated flavoring substances behave during storage in Frankfurter-type sausages. The diffusion behavior of seven selected aroma substances in the sausage matrix and the influence of the packaging and the casing were examined over a storage period of 28 days. The sausages were cut into uniformly thick layers at defined time intervals and examined by headspace-solid phase microextraction-gas chromatography-mass spectrometry. In general, three different groups could be distinguished: (1) even distribution over the entire product on the first day after smoking; (2) clear concentration gradient from outside to inside on the first day of storage, which leveled out until day 28 of storage; and (3) a clear concentration gradient that remained present throughout the storage period. In addition, only small effects were found in the distribution of flavorings between two types of packaging, selected casing, or different calibers.

Improving the colloidal stability of pectin-phycocyanin complexes by increasing the mixing ratio.

In the food industry, the phycobiliprotein phycocyanin acts as a color pigment or the functional part of the superfood "Spirulina." It is industrially extracted from Arthrospira platensis. Current scientific research is focusing on finding complex partners with the potential to stabilize phycocyanin against its sensitivity toward heating and pH changes. Less attention is paid to the factors that influence complexation. This study focuses on the mixing ratio of phycocyanin with pectin. Phycocyanin concentration was fixed, and the mixing ratios ranged from 0.67 to 2.50 (pectin:phycocyanin). All samples were analyzed for their color, size, microscopic structure, zeta potential, and sedimentation stability before and after heating at 85°C. It was found that increasing the pectin content fostered the initial interactions with the protein and chromophore, resulting in a color shift from blue to turquoise. The size of the complexes decreased from several micrometers to nanometers with increasing pectin concentration. Those smaller complexes that were formed at a mixing ratio of 2.5 showed a higher colloidal stability over a period of ∼2 days. It is suggested that at a low mixing ratio (0.67), phycocyanin cannot be completely entrapped within the complexes and attaches to the complex surface as well. This results in aggregation and precipitation of the complexes upon heating. With increasing aggregation and consequently size as well as density of the complexes, sedimentation was accelerated. PRACTICAL APPLICATION: Under acidic conditions, as found in many foods and beverages (e.g., soft drinks, hard candy), phycocyanin tends to agglomerate and lose its color. Specifically heating, triggers denaturation, causing phycocyanin to aggregate and lose vital protein-chromophore interactions necessary to maintain a blue color. To prevent precipitation of the phycocyanin-pectin complexes, increasing the amount of pectin to a ratio of at least 2.0 is effective. This illustrates how adjusting the mixing ratio improves stability. Conversely, lower mixing ratios  induce color precipitation, valuable in purification processes. Thus, practical use of biopolymer-complexes, requires determination of the optimal mixing ratio for the desired effect.

Anticipating food structure of meat products from mastication physics applying machine learning.

Alternatives to animal-based products are becoming more relevant. Most of those products rely at some stage on a structuring process; hence researchers are developing techniques to measure the goodness of the structured material. Conventionally, a typical sensory study or texture analysis by measuring deformation forces would be applied to test the produced material for its texture. However, meat alternatives and meat differ in more points than just the texture, making it hard to extract the isolated texture impression. To objectively obtain qualitative and quantitative differences between different food structures, evaluation of oral processing features is an upcoming technology which qualifies as promising addon to existing technologies. The kinematic data of the jaw and exerted forces regarding muscle activities are recorded during mastication. Resulting datasets are high in dimensionality, covering thousands of individual chews described by often more than ten features. Evaluating such a dataset could benefit from applying computational evaluation strategies designed for large datasets, such as machine learning and neural networks. The aim of this work was to assess the performance of machine learning algorithms such as Support Vector Machines and Artificial Neural Networks or ensemble learning algorithms like Extra Trees Classifier or Extreme Gradient Boosting. We evaluated different pre-processing techniques and various machine algorithms for learning models with regard to their performance measured with established benchmark values (Accuracy, Area under Receiver-Operating Curve score, F1 score, precision-recall Curve, Matthews Correlation Coefficient (MCC)). Results show remarkable performance of classification of each single chew between isotropic and anisotropic material (MCC up to 0.966). According to the feature importance, the lateral jaw movement was the most important feature for classification; however, all features were necessary for an optimal learning process.

Oral processing, rheology, and mechanical response: Relations in a two-phase food model with anisotropic compounds.

Food-material poses a challenging matrix for objective material scientific description that matches the consumers' perception. With eyes on the emerging structured food materials from alternative protein sources, objectively describing perceived texture characteristics became a topic of interest to the food industry. This work made use of the well-known methodologies of jaw tracking and electromyography from the field of "food oral processing" and compared outcomes with mechanical responses to the deformation of model food systems to meat alternatives. To enable transferability to meat alternative products, an anisotropic structuring ingredient for alternative products, high-moisture texturized vegetable protein (HM-TVP), was embedded in an isotropic hydrocolloid gel. Data of the jaw movement and muscle activities exerted during mastication were modeled in a linear mixed model and set in relation to characteristic values obtained from small- and large-strain deformation. For improvement of the model fit, this work makes use of two new data-processing strategies in the field of oral processing: (i) Muscle activity data were set in relation to true forces and (ii) measured data were standardized and subjected to dimensional reduction. Based on that, model terms showed decreased p-values on various oral processing features. As a key outcome, it could be shown that an anisotropic structured phase induces more lateral jaw movement than isotropic samples, as was shown in meat model systems.

A review on the relation between grinding process and quality of ground meat.

This review is providing an overview of the actual and past research in the field of ground meat. The forces that are acting in the meat grinder are well understood. The higher the forces that are acting on the meat while grinding, the stronger the disintegration of the meat cells after the process. These forces can be calculated as energy transfer in meat grinders using specific mechanical energy (SME). The amount of non-intact cells (ANIC) can be used to describe the extent of disintegrated cells. Different methods are available to rate the quality of ground meat, which is mainly influenced by the raw material and processing. Over the past decades of industrialization, the landscape of ground meat production has changed. However, the effects of the process adjustments on the quality of ground meat are not yet sufficiently described in the literature.

Meat color and iridescence: Origin, analysis, and approaches to modulation.

Meat color is an important aspect for the meat industry since it strongly determines the consumers' perception of product quality and thereby significantly influences the purchase decision. Emergence of new vegan meat analogs has renewed interest in the fundamental aspects of meat color in order to replicate it. The appearance of meat is based on a complex interplay between the pigment-based meat color from myoglobin and its chemical forms and light scattering from the muscle's microstructure. While myoglobin biochemistry and pigment-based meat color have been extensively studied, research on the physicochemical contribution of light scattering to meat color and the special case of structural colors causing meat iridescence has received only little attention. Former review articles focused mostly on the biochemical or physical mechanisms rather than the interplay between them, in particular the role that structural colors play. While from an economic point of view, meat iridescence might be considered negligible, an enhanced understanding of the underlying mechanisms and the interactions of light with meat microstructures can improve our overall understanding of meat color. Therefore, this review discusses both biochemical and physicochemical aspects of meat color including the origin of structural colors, highlights new color measurement methodologies suitable to investigate color phenomena such as meat iridescence, and finally presents approaches to modulate meat color in terms of base composition, additives, and processing.

The impact of temperature-controlled smoldering smoking on polycyclic aromatic hydrocarbons and heterocyclic amines contents in Frankfurter-type sausages.

The impact of temperature-controlled smoldering smoking conditions on the accumulations of polycyclic aromatic hydrocarbons (PAHs) and heterocyclic amines (HAs) in Frankfurter-type sausages was investigated. Depending on the temperature, smoking can be divided into two phases: an unstable pyrolysis stage (≈ 200 s) and a stable pyrolysis stage (>200 s), which had different effects on hazardous substances contents. The unstable pyrolysis stage, which contributed 66.9 âˆ¼ 89.6% of PAH accumulations by comparing with sausages smoked for 15 min, has significant impact on high PAH residues. By contrast, the contents of HAs showed steady increase trends with smoking time. Few types of free-HAs with low concentrations (3.05 âˆ¼ 22.9 ng/g DW), but more types of bound-HAs with much higher levels (10.8 âˆ¼ 396 ng/g DW) were found. In addition, the formation of some HAs followed the first-order reaction model. However, the detailed formation mechanisms of PAHs and HAs under temperature-controlled smoldering smoking conditions remain to be studied.

Fibrous food and particle size influence electromyography and the kinematics of oral processing.

Structure-sensory relationships are essential for understanding food perception. Food microstructure impacts how a food is comminuted and processed by the human masticatory system. This study investigated the impact of anisotropic structures, explicitly the structure of meat fibers, on the dynamic process of mastication. For a general understanding of texture-structure relationships, the three typically used deformation-tests: Kramer shear cell-, Guillotine cutting- and texture-profile-analyses were conducted. 3D jaw movements and muscle activities of the masseter muscle were additionally tracked and visualized using a mathematical model. Particle size had a significant effect on jaw movements and muscle activities for both the homogeneous (isotropic) and fibrous (anisotropic) meat-based samples with the same composition. Mastication was described using jaw movement and muscle activity parameters determined for each individual chew. The adjusted effect of fiber length was extracted from the data, suggesting that longer fibers induce a more strenuous chewing in which the jaw undergoes faster and wider movements requiring more muscle activity. To the authors' knowledge, this paper presents a novel data analysis approach for identifying oral processing behavior differences. This is an advancement on previous studies because a holistic overview of the entire mastication process can be visualized.

Meat hybrids-An assessment of sensorial aspects, consumer acceptance, and nutritional properties.

So-called meat hybrids are a new class of products where a fraction of the meat product (e.g., 20%) is replaced with alternative protein sources, such as plant-based ones. Research suggests that these products could serve as a low-threshold offer for a specific target group that wants to cut down on meat, thereby facilitating the transition toward a more healthy and sustainable diet. Nonetheless, data demonstrate that meat hybrids with a high substantial meat substitution level often fail in the market. This study summarises findings on the physicochemical properties, sensory, and acceptance of six different meat hybrids (70% meat and 30% plant proteins) that were collected in the framework of a case study in the project AiF 196 EN. For this purpose, sensory characteristics were collected via two QDA sessions and a hedonic consumer test. Furthermore, the hybrid recipes were analysed in their proximate composition. The respective recipes varied in protein source (soybean, pumpkin, and pea) and mode of incorporation [textured vegetable protein (TVP), high moisture extrudate (HME)]. It was shown that a meat hybrid with a relatively high share of 30% plant-based proteins with peas as a protein source and TVP as a processing method can still attract consumers.

Solidification of concentrated pea protein-pectin mixtures as potential binder.

BACKGROUND: Binders in plant-based meat analogues allow different components, such as extrudate and fat particles, to stick together. Typically, binders then are solidified to transform the mass into a non-sticky, solid product. As an option for a clean-label binder possessing such properties, the solidification behavior of pea protein-pectin mixtures (250 g kg-1 , r = 2:1, pH 6) was investigated upon heating, and upon addition of calcium, transglutaminase, and laccase, or by combinations thereof. RESULTS: Mixtures of (homogenized) pea protein and apple pectin had higher elastic moduli and consistency coefficients and lower frequency dependencies upon calcium addition. This indicated that calcium physically cross-linked pectin chains that formed the continuous phase in the biopolymer matrix. The highest degree of solidification was obtained with a mixture of pea protein and sugar beet pectin upon addition of laccase that covalently cross-linked both biopolymers involved. All solidified mixtures lost their stickiness. A mixture of soluble pea protein and apple pectin solidified only slightly through calcium and transglutaminase, probably due to differences in the microstructural arrangement of the biopolymers. CONCLUSION: The chemical makeup of the biopolymers and their spatial distribution determines solidification behavior in concentrated biopolymer mixtures. In general, pea protein-pectin mixtures can solidify and therefore have the potential to act as binders in meat analogues. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A research note: Effect of Hofmeister salts on meat iridescence in cooked pork.

The effect of Hofmeister salts (NaCl, NaSCN, Na2SO4, KCl, LiCl, CaCl2) on surface iridescence in cooked pork was investigated. Strongest iridescence occurred in samples treated with NaSCN, NaCl and KCl. Control samples and LiCl, CaCl2 and Na2SO4 treatments showed weaker iridescence. However, differences between KCl and LiCl, CaCl2 and Na2SO4 were not statistically significant (p > 0.05). Nevertheless, a tendency of chaotropic salts (NaSCN, NaCl, KCl) to cause stronger iridescence was noted that might be explained with a more effective solubilization of myofibrillar proteins (MPs), reducing incoherent scattering from the myofibrils and thus enhancing multilayer interference.

Technologies for sustainable heat generation in food processing.

The utilization of heat is one of the foundations of modern food processing. At present, boilers that operate on fossil fuels are still dominating the generation of hot water, steam, and hot air in the food industry. In light of sustainability goals and carbon taxes as well as international efforts to reduce the dependence on natural gas, new technologies are needed to lower the greenhouse gas emissions related to thermal processing of foods. This review discusses important technologies that could serve as a replacement for conventional fossil fuel boilers in the future. These technologies are based on electricity, geothermal energy (direct/indirect use), and electricity to hydrogen conversion and include fuel cells, microturbines, engines, electrical boilers, heat pumps, radiation, and use of geothermal energy. The majority of these technologies are already available for implementation at larger scales and emissions are generally lower compared to burning fossil fuels. At present, major obstacles, such as low fossil fuel prices, still exist that prevent the widespread adoption of more sustainable heating technologies. However, the direct transformation of electrical energy and utilization of geothermal energy for heating purposes seem promising and should be more frequently installed in the future, whereas the use of H2 obtained through electrolysis as a transportable source of energy may also serve as a source of thermal energy where it is useful to generate electricity and heat on the production site or where the availability of electricity is limited.

Homogenization improves foaming properties of insoluble pea proteins.

Foams are essential in many food applications and require surface-active ingredients such as proteins for formation and stabilization. We investigated the influence of high-pressure homogenization on foaming properties of insoluble pea protein dispersions (5% w/w) at pH 3 and 5. Unhomogenized insoluble pea protein dispersions did not foam at either pH 3 or 5, as they consisted of large insoluble pea protein aggregates with limited surface activity. At pH 3, the homogenized pea protein dispersions generated foams due to higher protein solubility and surface activity through disruption of large protein aggregates into smaller particles. The foam stability decreased with increasing homogenization pressure and number of cycles due to a reduction in continuous phase viscosity. At pH 5, the insoluble pea proteins foamed when the homogenization resulted in formation of aggregates made of smaller protein entities, which was the case for homogenization ≥ 100 MPa and three cycles. In general, the foam capacity (amount of formed foam) was higher at pH 3 due to improved protein solubility and surface activity that facilitated incorporation of air, while the foam stability (resistance against foam collapse) was better at pH 5 because of the presence of larger protein aggregates that formed thicker and more viscous films around the air bubbles benefitting retention of gas bubbles. Overall, homogenization improved the foaming properties of insoluble pea proteins at pH 3 and 5. Practical Application Insoluble pea protein dispersions formed foams at pH 3 and 5 after homogenization highlighting the potential of this processing step for the food industry. The improvement in functionality of plant-derived ingredients helps to increase their use for consumer goods, thereby supporting the transition to more sustainable food system.

Insights into characterizing and producing anisotropic food structures.

Besides the flavor profile of food, texture plays a major role in terms of the acceptance and likeability of food products. In contrast to gel-like homogenous isotropic structures, where the characterization is established and structure-texture mechanisms are well understood, there is still a lack of knowledge in the field of anisotropic complex food matrices. Food systems that show anisotropic properties in terms of macroscopic mechanical anisotropy as in grown meat, or mixed complex systems where anisotropic shaped particles or fibers are embedded into an isotropic matrix are challenging to characterize, hence the structure-texture correlation is not trivial to understand. In this paper, we bring together the state of the art of different anisotropic structures as a source of food, their formation in terms of structured plant proteins, and consequently the structure-texture correlation of those. Characteristic terms and properties to differentiate between anisotropic systems are introduced with the purpose to facilitate characterization of those. Based on the here provided terms and characteristics, further studies toward understanding such systems and their perception can be conducted. Beyond that, a first opinion on crucial influencing factors on the perception of anisotropic systems and their mechanistic background is provided.

Effects of Electrospun Potato Protein-Maltodextrin Mixtures and Thermal Glycation on Trypsin Inhibitor Activity.

Fibers of potato protein and polysaccharides were obtained by needleless electrospinning. Mixtures of maltodextrin DE2 (dextrose equivalent) (0.8 g/mL), DE21 (0.1 g/mL), and different concentrations of potato protein (0.05, 0.1, 0.15, and 0.2 g/mL) were used for fiber production. Glycation was performed via the Maillard reaction after thermal treatment (0/6/12/24/48 h, 65 °C, 75% relative humidity). The effects of electrospinning and heating on trypsin inhibitor activity (IA) were studied. The results of the IA assay showed that electrospinning and glycation caused significant differences in IA among blends, heating times, and the interaction of blend and heating time (p < 0.001). The higher the protein content in the fibers, the higher the IA. The lowest IA was found in the mixture with the lowest protein content after 48 h. In other blends, the minimum IAs were found between 6 and 12 h of heating. The determination of the free lysine groups showed a nonsignificant decrease after heating. However, higher free lysine groups per protein (6.3−9.5 g/100 g) were found in unheated fibers than in the potato protein isolate (6.0 ± 0.5 g/100 g). The amide I and amide II regions, detected by the Fourier transform infrared spectra, showed only a slight shift after heating.

Acidification behavior of mixtures of pork meat and wet texturized plant proteins in a minced model system.

The increasing use of wet texturized plant proteins as meat substitutes requires a characterization of their functional properties, especially in terms of pH-behavior when being mixed with meat proteins to create so-called hybrid products. In this study, a minced model system containing pork meat, curing salt, and various amounts (0-100 wt%) of wet extruded proteins from pea (Pea I, II), pumpkin (Pumpkin I, II, III), and sunflower was used to evaluate the effect of mixing on pH and time-dependent pH-changes upon the addition of glucono-delta-lactone (GDL). Increasing concentrations of plant extrudates resulted in a linear increase of the initial (pH0h ), intermediate (pH6h ), and final pH48h for all samples and higher slopes at higher native pH of extrudates were found. Acidification kinetics of all samples were similar with a distinct pH-drop by 0.3 to 0.8 pH-units per wt% GDL in the first 6 h, followed by a plateau where pH remained constant. At extrudate concentrations of 5 wt% (Pea I, II, Pumpkin I, II) or 15 wt% (Pumpkin III, Sunflower), a sufficient acidification with typically used GDL-amounts ( = 1 wt%) could be achieved, while higher plant protein contents required higher GDL-concentrations in order to reach a pH value of 5.0; a common target value in dry-cured sausages. A mathematical model was proposed to correlate pH, time, acidifier, extrudate concentration, and plant protein origin, to aid in the adjustment of dry-cured hybrid meat formulations, and to describe thresholds of the feasible extrudate and acidifier concentrations. PRACTICAL APPLICATION: Despite the increasing relevance of texturized plant proteins as meat mimetics, little is known about their functional and process-related properties. This study shows that plant protein origin, the level of meat replacement, and the amount of acidifier are linked to the time-dependent pH-value on the basis of a mathematical model. This brings food developers one step closer in creating tailored formulations and estimating the effects of these novel ingredients in the final product characteristics of hybrid meats and analogues.

A research note: effect of pH on meat iridescence in precooked cured pork.

OBJECTIVE: The objective of this study was to investigate the effect of pH change of cooked cured pork M. longissimus thoracis et lumborum on iridescence intensity and extent (= percentage of iridescent area) since interaction with light may be related to pH-induced alterations in microstructure. Muscles were injected with brines of different pH values, cooked, sliced perpendicular to muscle fiber direction, and visually evaluated by a panel of 20 experienced panelists. RESULTS: Muscles with lowest pH (5.38) showed the lowest iridescence score of 4.63 (p < 0.05). Iridescence was greatest in muscles with normal (5.78) and high pH (6.03, respectively 6.59), but did not differ significantly (p > 0.05). Iridescence was positively correlated (p < 0.01) with pH and water content, and negatively correlated (p < 0.01) with cooking loss. Hence, hydration state and light scattering from microstructure may be important factors that determine the degree of iridescence in cooked meat products.

Thermal and acidic denaturation of phycocyanin from Arthrospira platensis: Effects of complexation with λ-carrageenan on blue color stability.

The pH and temperature sensitivity of the natural blue pigment phycocyanin from Arthrospira platensis limits its application as food colorant. This study examines the effect of protein stabilization by the anionic polysaccharide λ-carrageenan on phycocyanins color appearance at pH 2.5-6.0, unheated and after heat treatments (70/90 °C). Electrostatic interactions, hydrophobic interactions, hydrogen bonds and disulfide-bridges were assessed by adding NaCl, urea and dithiothreitol (DTT) to the samples. Measurements of the zeta potential, transmittance and two-dimensional gel electrophoresis coupled to mass spectrometry confirmed electrostatic interactions around the zero surface charge of phycocyanin over a broad pH range (∼4.1-6.4). Despite a color shift towards turquoise, the color remained stable during heating, especially below of pH 3.5. Precipitation was inhibited over the entire pH range. Overall, electrostatic complexation of phycocyanin and λ-carrageenan is a promising technique to stabilize proteinaceous colorants, helping to reduce food waste and foster a shift to renewable materials.

Effect of varying pH on solution interactions of soluble meat proteins with different plant proteins.

The exchange of animal-based for plant-based proteins is becoming more and more popular due to an increasing demand for alternative and more sustainable protein sources. In this study, solubilized water- (ws) or salt-and-water (sws) meat proteins were evaluated in their pH-dependent interactions with soluble protein fractions from wheat, pumpkin, sunflower, rapeseed, or potato proteins. For this purpose, 1 : 1 (v/v) mixtures of 1.0 wt% meat (ws or sws) and plant proteins were prepared at a sodium chloride concentration of 1.8 wt% (ionic strength: 0.31 mol L-1) and adjusted to different pH-values in between 4.5-7.0. While only slight differences were found upon comparison of interactions of ws and sws batches (p > 0.05), interactions among these animal-based and soluble plant proteins took place. First, optical observations, light microscopy, and SDS-PAGE revealed increasing protein solubility with increasing pH. Second, particle size distributions (PSDs) revealed a shift towards slightly larger particle sizes e.g. at pH 5.3 and 7.0 with d4,3 of 43.2 and 21.3 µm (sws) to 45.4 and 23.9 µm (sws + potato), respectively. Furthermore, heat-induced gel formation was improved at pH > 6.0, in particular in mixtures of meat and wheat or rapeseed proteins that formed a homogenous gel structure. Based on the obtained results, protein-protein complexations mainly by electrostatic forces are suggested which occur due to various pI of meat and plant proteins e.g. pH 7.5 (wheat), 7.2 (potato), and 6.6 (rapeseed) in comparison to 5.1 (ws) and 5.6 (sws). The filamentous microstructure of some gels (soluble fraction of rapeseed, potato and wheat proteins) led to the assumption that meat proteins, mainly at pH values greater than 5.8 (optimally ≥6.5), had a structuring effect on plant proteins.

Pickering emulsion stabilized by hydrolyzed starch: Effect of the molecular weight.

HYPOTHESIS: The emulsifying ability of starch is influenced by its molecular weight. Reducing the molecular weight of starch is expected to influence interfacial adsorption and membrane elasticities, thereby affecting its emulsifying ability through Pickering effects. Hence, it should be possible to tailor the emulsifying ability of starch by adjusting its molecular weight. EXPERIMENTS: Waxy corn starch (CS) and rice starch (RS) were hydrolyzed with pullulanase to obtain high (HM) and low molecular weight (LM) fractions. After the molecular weight was determined by size exclusion chromatography, the fractions were used to prepare model oil-in-water emulsions. The stability, microscopy, and particle size of the emulsions were characterized, and the underlying emulsification mechanism was subsequently studied through dynamic laser scattering, surface tension analysis, interfacial rheology, and Pearson's correlation calculations. FINDINGS: In the molecular weight range obtained in this study, the smaller the molecular weight of starch, the stronger its emulsifying ability. The decrease in molecular weight resulted in considerable different adsorption and interfacial elasticities with smaller fractions occupying less area on the interface and forming interfaces with higher elasticities, resulting in higher stabilities through Pickering effects. Results thus suggest that the emulsifying ability of starch may be tailored by adjusting its molecular weight.