Meat analogue research and development focuses on the production of sustainable products that recreate conventional meat in its physical sensations (texture, appearance, taste, etc.) and nutritional ...aspects. Minced products, like burger patties and nuggets, muscle-type products, like chicken or steak-like cuts, and emulsion products, like Frankfurter and Mortadella type sausages, are the major categories of meat analogues. In this review, we discuss key ingredients for the production of these novel products, with special focus on protein sources, and underline the importance of ingredient functionality. Our observation is that structuring processes are optimized based on ingredients that were not originally designed for meat analogues applications. Therefore, mixing and blending different plant materials to obtain superior functionality is for now the common practice. We observed though that an alternative approach towards the use of ingredients such as flours, is gaining more interest. The emphasis, in this case, is on functionality towards use in meat analogues, rather than classical functionality such as purity and solubility. Another trend is the exploration of novel protein sources such as seaweed, algae and proteins produced via fermentation (cellular agriculture).
Many food ingredients such as polyphenols, phenolic acids (e.g. present in fruit and vegetables) and organosulphur compounds (e.g. present in mustard, garlic and chives) covalently interact with ...meat, egg, dairy and plant-based proteins. The results of those interactions are manifold and range from altered technological properties (in emulsions, foams, gels) to sensory changes (colour formation, altered taste and smell) and different biological activity (allergy, antimicrobial effects, hydrolysis).
The present review discusses both the positive and the negative side effects of such interactions and explores the potential to fine-tune protein functionality during processing not only in model solutions but also in more complex foods.
Traditionally, studies have focused on the negative effects of interactions between protein and plant ingredients (e.g. discolouration and solubility changes), but more recent studies highlight positive effects (e.g. enhanced emulsifying capacity, reduced allergy and targeted production of protein pigments). By controlling food processing conditions (e.g. protein nativity) and the food matrix (e.g. presence of antioxidative compounds or thiol groups, pH value during storage), the observed effects can be prevented or induced. On the basis of the listed findings, future processes can be developed that take such interactions into account to enable targeted co-processing of plant compounds with proteins. A better understanding of these interactions opens up a wealth of novel utilization potential.
•Amyloid aggregates at pH 2 and pH 3.5 differed in their building blocks.•All aggregate building blocks changed towards smaller peptides after >48 h incubation.•Apparent dityrosine oxidation reached ...a maximum after 5 h incubation.•Protein carbonyls were not significantly increased during the first 5 h of fibril preparation.•The amyloid aggregates were deteriorated after 72 h incubation.
Although the connection between protein oxidation, amyloid aggregation and diseases such as Alzheimer’s is well known there is no information on such effects during preparation of beta-lactoglobulin fibrils. Different morphologies of amyloid aggregates of beta-lactoglobulin were prepared by incubation at pH 2 or pH 3.5 for up to 72 h. After 5 h, amyloid aggregates at pH 2 formed typical fibrils, which consisted of peptides. At pH 3.5, the amyloid aggregates were worm-like and consisted of intact protein. After 72 h, the building blocks at both pH values changed towards smaller peptides. The apparent tyrosine oxidation reached a maximum after 5 h at both pH values, whereas N-formylkynurenine and carbonyls increased continuously during 72 h. In case amyloid structures are used as edible material, the health related effects caused by protein oxidation needs to be considered.
The covalent interactions between whey protein isolate (WPI) and rosmarinic acid (RosA) at two different conditions, alkaline (pH 9) and enzymatic (in the presence of tyrosinase, PPO), at room ...temperature with free atmospheric air were studied. The conjugates formed between WPI and RosA were characterized in terms of their physicochemical and functional properties. The changes in protein structure were analyzed by intrinsic fluorescence and binding of 8‐anilino‐1‐naphthalenesulfonic acid. The findings show that the covalent interactions caused a decrease in free amino and thiol groups and tryptophan content at both conditions. The decrease at enzymatic conditions was lower than at alkaline conditions. In addition, modified WPI at alkaline conditions exhibited higher antioxidative capacity compared to the modification at enzymatic conditions. However, WPI modified at enzymatic condition showed mild antimicrobial activity against Staphylococcus aureus LMG 10147 and MU50 compared to WPI modified at alkaline conditions and unmodified WPI (control). The modified WPI can be used as multifunctional ingredient into various food products with an additional health promoting effect of the bound phenolic compounds.
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•Lipid induced scission peptides are located on the surface of the protein in random coil segments.•Scission is especially present at the N- and C-terminus of ...beta-lactoglobulin.•Cysteine and aliphatic amino acids were most important cleavage sites.•The α-amidation pathway was the predominant mechanism in this study.•The comparison of various oxidants of proteins are compared to their ability of protein scission and modification.
Lipid oxidation induced protein scission was investigated in oleogel using beta-lactoglobulin (whey protein isolate) as gelator. Extracted cleaved peptides were measured using high resolution mass spectrometry (FT-ICR-MS), which was provided by an automatically generated annotation list approach to identify relevant masses and sum formula using the isotopic pattern. The identified oxidized peptides were then further evaluated using partial least squares regression to relevant lipid hydroperoxide formation data, which provide the significance and importance of the peptides toward lipid induced scission. Thereby, the most important peptides are located at the surface of the protein in random coil segments and especially at the ends of the protein sequence. The most important amino acids were cysteine and aliphatic amino acids, which undergo scission mostly by the α-amidation pathway. The findings compare well with studies investigating depletion of amino acids initiated by lipid oxidation in systems containing bovine albumin or gamma-globulin.
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•Molecular interactions between QS and β-LG at o/w significantly differ from a/w.•QS dominates the interfacial film as shown by pendant drop experiments.•Mixed films show a ...concentration-dependent strain stiffening upon dilational stress.•Lateral interactions between QS and β-LG occur in mixed films as indicated by G*.•Changes in dispersity are influenced by concentration and ratio of QS and β-LG.
Aim of the present study was to investigate the interfacial properties of mixed films of Quillaja saponins (QS) and beta-lactoglobulin (β-LG) at the oil/water-interface. It was hypothesized that due to the differences in the physical characteristics of the dispersed phase molecular interactions and film characteristics at the oil/water interface substantially differ from the air/water-interface. Furthermore QS/β-LG-interactions will affect stability of emulsions in a concentration-dependent manner. Oscillating drop experiments were performed with subsequent analysis of raw data (Lissajous-plots) to discover non-linear behavior upon compression and expansion. Interfacial shear rheology as well as dynamic interfacial tension and two-fluid needle experiments were performed to comprehensively characterize interfacial properties of mixtures of QS/β-LG. Finally, emulsions were prepared and their stability, oil droplet size and ζ-potential were determined. It became obvious that QS dominates the interfacial film in a binary mixture as indicated by dynamic interfacial tension and dilational rheology. Strain stiffening was observed for mixed QS/β-LG interfacial layers upon dilational expansion at an amplitude above 2.8%. Intermolecular interactions increased in mixtures of QS/β-LG as indicated by shear rheology. Emulsion experiments showed extensive aggregation of oil droplets in QS/β-LG-emulsions with high content of β-LG. Aggregation of oil droplets increased velocity of creaming and after 7days a distinct creaming layer was visible. Changes in dispersity were influenced by concentration and ratio of QS and β-LG.
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•pH 2 and pH 3.5 amyloid aggregate solution differ in their polydispersity.•Mixtures of amyloid and non-amyloids were compared with separated fractions.•Separated amyloid fractions ...differ in size and charge properties.•Separation reduced superposition effects for FTIR, Trp fluorescence and ThT analysis.
It is well known that amyloid beta-lactoglobulin (BLG) fibril solutions contain a heterogeneous mixture of amyloid aggregates and non-amyloid material. However, few information are available on how strongly separated fractions of different morphologies (straight fibrils at pH 2 and worm-like aggregates at pH 3.5) vary with respect to physicochemical properties and building blocks as most analyses are conducted with unfractionized solutions where superposition effects occur.
The pH-value shift resulted in an altered degree of acid hydrolysis which led to dissimilar building blocks of the aggregates (peptides at pH 2, non-hydrolyzed protein at pH 3.5). The respective separated amyloid and non-amyloid fractions showed significantly different size (SAXS, SEC, AUC) and charge properties (Zeta potential) than the whole samples. Strong superposition effects were evident with common analyses such as FTIR, TRP fluorescence and Thioflavin-T. At the same time, structural differences of pH 2 and pH 3.5 aggregates could be presented more clearly.
•Whey protein oleogels with low (<0.23%) and high (>2.8%) water addition differ in their oxidation profiles.•Fluorescence increases indicate strong protein oxidation levels even with low lipid ...oxidation.•Primary amines and protein carbonyls degrade and only accumulate at high oxidation levels.•Typical lipid oxidation aldehydes decompose in protein oleogels.
Protein- and lipid oxidation were investigated in whey protein based oleogels with varying water addition. Lipid oxidation was low (~30 mmol O2/kg lipid hydroperoxides after 6 weeks) in gels with < 0.23% water and a high (>1,000 mmol O2/kg lipid hydroperoxides after 4 weeks) in gels with > 2.4% water addition. In systems with > 2.4% water addition fluorescence (excitation 325 nm / emission 410 nm) as indicator of tyrosine oxidation and carbonyl content significantly increased and remained at low levels in oleogels with < 0.23% water addition. Primary amines as indicator for protein backbone breakage increased in early stages of oxidation in high water oleogels and decreased after 28 days. Degradation has been suggested to occur through interactions with reactive secondary lipid oxidation products and was confirmed by spiking experiments using respective compounds. The results suggest that secondary lipid oxidation markers are masked dependent on water addition in the presence of proteins.
Rapeseed protein concentrate (RPC) and isolate (RPI) were fractionated from rapeseed meal and their techno-functional properties were characterized. RPC prepared by aqueous ethanolic washing process ...yielded less refined and insoluble fractions with largely denatured protein. Hydrated insoluble RPC particles held 6.7 g water without swelling. RPI fractionated from aqueous extraction and ultrafiltration still contained certain phenolic compounds but protein nativity was preserved including a high protein solubility of 78%. RPC dispersion with 40 w/w % showed the highest apparent complex modulus G* among all rapeseed materials. In contrast, the G* for RPI dispersion increased upon heating, suggesting a thermal induced denaturation and gelation capacity of the proteins. Thus, a largely denatured RPC free of phenolic compounds or a native but phenolic containing RPI were obtained by the applied processing conditions, which differ in their techno-functional properties and thus have different promising application potential in food applications.
The growing demand for plant as opposed to animal protein has sparked the interest of exploring currently underutilized plant protein sources in food industry. Rapeseed by-products obtained after oil extraction are promising but the presence of anti-nutritional components in rapeseed meal presents a barrier for its usage in food products. Aqueous ethanolic washing or aqueous extraction combined with membrane filtration were applied to remove the antinutritional factors from rapeseed meal to yield rapeseed protein concentrates and even more refined isolates. In this work, the functional properties of the fractionated rapeseed materials were characterized for its relevance in food applications. The similarities of the rheological properties between rapeseed protein concentrates and soy materials, as well as presence of native proteins in RPI might suggest their potential for diverse in food industry applications.
•Aqueous ethanol washing yielded rapeseed protein concentrate with enhanced rheological properties.•Rheological properties of rapeseed concentrate were similar to those of soy protein concentrate.•Effective removal of phenolic compounds by aqueous ethanol washing of rapeseed meal.•Nativity of rapeseed protein was preserved by aqueous extraction and ultrafiltration.•Rapeseed protein concentrate and isolate have both high potential for food applications.
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•Protein loss can be limited with increasing ethanolic ratios.•Preventing protein loss is more important than phenolic compounds removal for selecting process condition.•Aqueous ...ethanolic washing preserved sunflower protein nativity and solubility at high ethanol content.•Optimized process conditions can be achieved with increasing washing steps using high ethanol content.
Selective removal of phenolic compounds (PCs) from de-oiled sunflower kernel is generally considered a key step for food applications, but this often leads to protein loss. PC removal yield and protein loss were assessed during an aqueous or aqueous ethanol washing process with different temperatures, pH-values and ethanol contents. PC yield and protein loss increased when the ethanol content was < 60% or when a higher temperature was applied. Our main finding is that preventing protein loss should be the key objective when selecting process conditions. This can be achieved using solvents with high ethanol content. Simulation of the multi-step exhaustive process showed that process optimization is possible with additional washing steps. PC yield of 95% can be achieved with only 1% protein loss using 9 steps and 80% ethanol content at 25℃. The functional properties of the resulting concentrates were hardly altered with the use of high ethanol solvents.
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