Academia.eduAcademia.edu

Outline

Title
Abstract

Food Chemistry Proteins1a

Profile image of Mortec ClassisMortec Classis

Abstract
sparkles

AI

The text explores the fundamental aspects of peptides and proteins, focusing on their formation, structure, and biological functions. It describes the processes of peptide bond formation through condensation reactions, the significance of protein hydrolysis, and the structural hierarchy of proteins spanning primary to quaternary levels. Insights into intermolecular interactions, particularly involving disulfide bonds and the impact of sequence and amino acid composition on protein properties, are discussed in the context of food chemistry.

Related papers

Aspects of physical and chemical alterations to proteins during food processing – some implications for nutrition
Kevin Sutton

British Journal of Nutrition, 2012

In this paper, we give an overview of our research exploring the impact of physical and chemical processing on food proteins. There are three themes, applied to the proteins of wheat, soya, egg and dairy foods. Firstly, the impact of the Maillard reaction on food proteins is discussed, with a particular focus on how the reactions might be harnessed to manipulate food texture. Secondly, the potential of enzymatic protein-protein crosslinking is considered, especially the enzyme transglutaminase. Thirdly, the broader question of how the aggregation of proteins within a food is altered by chemical and physical modification and how, in turn, this might impact on the overall nutritional quality of the food is considered.

View PDFchevron_right
Protein Processing in Food and Bioproduct Manufacturing and Techniques for Analysis
Chockry Barbana

Dunford/Food and Industrial Bioproducts and Bioprocessing, 2012

View PDFchevron_right
Physicochemical properties structural characteristics and in v 2023 Food Hy[1]
Juan Du, jose oscar branco pereira

The present study sought to use microbial transglutaminase (MTG) to modulate the physicochemical properties of brown rice protein isolate (BRPI), pea protein isolate (PPI) and their blend, and determine MTG's effect on protein structural and digestive profile changes. MTG at concentration of 1 U/g significantly increased water holding capacity (91.6% enhancement) and decreased oil holding capacity (39.3% reduction) of BRPI + PPI (4:6) blend, respectively, accompanied by decreasing their solubility and zeta potential values in aqueous system. From rheological analysis, MTG-induced crosslinks could result in stronger and more elastic gels in BRPI + PPI blend with lower gel point temperature. SDS-PAGE demonstrated that the number and intensities of the protein bands for all MTG-treated BRPI were similar under both non-reducing and reducing conditions, whereas in the samples containing PPI, fewer and fainter bands were shown in the groups treated by MTG at concentration of 4 U/g and above. From FTIR spectra, lower level of random coils paralleled by an increase in both β-sheet structures and α-helix band were observed in the 1.0 U/g MTG-treated BRPI + PPI blend, indicating the proteinprotein interactions within the mixed systems might boost the role of MTG in the structural modification, facilitating the network formation of more ordered structure with better thermal stability. Results of in vitro digestion showed less hydrophobic amino acids and essential amino acids including Lys released in MTG-treated BRPI + PPI blend's digests. Overall, the application of MTG in plant-based proteins can potentially contribute to the development of innovative food products with modified functionalities and unique digestive characteristics.

View PDFchevron_right
Amino acid, peptides & proteins
magendira mani vinayagam
View PDFchevron_right
The Analysis Techniques Of Amino Acid And Protein In Food And Agricultural Products
ELAZMANAWATI LEMBONG

International Journal of Scientific & Technology Research, 2020

The protein content in food and agricultural products affects the physicochemical and nutritional properties of these products. This review aims to discuss the analysis techniques of protein and amino acid in food and agricultural products. The qualitative analysis can be conducted using the Hopkins-Cole, Xanthoproteic, Millon, Nitroprusside, and Sakaguchi test. In contrast, the quantitative analysis of proteins can use the Kjehldahl, Biuret, Lowry, UV Spectrophotometry, and Turbidimetry. It also discussed the immunohistochemical techniques to identify cellular or tissue constituents (antigens) by staining techniques, while Formol titration measures the hydrolysis of proteins and N-amino quickly. The amino acids can be analyzed by microbiological methods, colorimetric, high-performance liquid chromatography (HPLC), and gravimetric techniques. These methods/techniques can be chosen according to the type of sample and the purpose of the analysis so that the results can be obtained acc...

View PDFchevron_right
Protein and amino acid
Michael A Ameny

Protein and Amino Acid contents of four whitefleshed African sweetpotatoes and American groundnut M. A. Ameny and P. Wilson ^1 Department of Food Science and Technology, Makerere University, P.O. Box 7062, Kampala, Uganda ^1 Department of Horticulture, Louisiana Agricultural Experimental Station, Louisiana State University, Agricultural Center, Baton Rouge, LA. 70803, USA (Received 10 April, 1996; accepted 30 June, 1996) Code Number: CS96061 Sizes of Files: Text: Graphics: Tables (gif) - 55.5 ABSTRACT White flesh sweetpotatoes (Ipomoea batatas (L.) Lam) are a major food crop in developing countries. The purpose of this study was to evaluate the protein and amino acid content of four white fleshed African sweetpotato roots and Apios americana tubers (American groundnuts). Although the sweetpotato and Apios are not normally considered sources of proteins, the wide use of sweetpotatoes as a source of carbohydrate and the renewed interest in Apios warrant the study of proteins in these crops. Protein content ranged from 4.26 to 8.23% of fresh weight even after pureeing and freeze-drying. One sweetpotato cultivar T1702 had a higher protein content and quality than the others based on amino acid profile evaluation. Processing into puree reduced most of the amino acids to varying degrees. There was a difference in amino acids among sweetpotato cultivars (P<0.05) and between sweetpotatoes and Apios. Apios had a higher level of protein than the sweetpotatoes before and after processing into puree. Two fractions of proteins were identified, namely a "whitle" and a "chomoplast" protein... white and chromoplast protein fractions. The white protein had a higher percentage of both protein and amino acids. Key Words: Apios americana, Ipomoea batatas RESUME Les patates douces e chaire blanche (Ipomoea batatas (L.) Lam) constituent un aliment de base dans les pays en voie de developpement. Le but de cette recherche est d'evaluer la teneur en proteine et en amino acide de quatre patates douces africaines e chaires blanches et les gousses d'Apios americana. Bien que la patate douce et l'Apios ne sont pas normalement consideres comme sources des proteines, l'utilisation considerable de patate douce comme source de carbohydrate et l'interet renouvele dans le mandat en Apios justifient l'evaluation de proteines dans ces cultures. La patate douce et Apios ont des teneur en proteines variables entre 4,26 et 8,23% de poids frais meme apres avoir ete transforme en puree ou seche. Les donnees indiquent qu' un cultivar de patate douce (T 1702) avait une haute teneur et qualite de proteines, par rapport aux autres patates douces comme indique par le profil d'acides amines. Le fait de transformer la patate douce en puree reduisait le plupart des acides amines avec des degres variables et il y avait une difference significative entre les acides amines dans les cultivars de patate douce (P=0.05)/ et entre la patate douce et l'Apios. L'Apios avait un niveau

View PDFchevron_right
Protein mixtures and their nutritional properties optimized by response surface methodology
Inar Erger

Nutrition Research, 2000

View PDFchevron_right
Food proteins from animals and plants: Differences in the nutritional and functional properties
Julie Cakebread

Trends in Food Science &amp; Technology, 2022

Background: Animals and plants are the main sources of dietary proteins, and there are important differences in the type of protein that they supply. The differences include molecular structure, amino acid profile, digestibility, and technical functionality in food, i.e. the ability to gel, emulsify, bind water etc. These inherent differences influence their bioavailability from a human nutrition perspective, as well as the sensory quality of foods containing animal or plant proteins. These fundamental differences mean that designing plant-based foods to mimic animal foods requires much more than simple substitution of one ingredient with another. Scope and approach: We survey some of the nutritional and technological functionality data for animal-and plantderived food proteins and discuss the nature and implications of the differences between them. Key findings and conclusions: Plant-based foods typically provide less complete protein nutrition because of lower digestibility and source-specific deficiencies in essential amino acids, compared with animal proteins. Such differences may not be as essential for adults as they are for infants and young children, due to their developmental requirements. Plant proteins can be subjected to various processes to bring their functionality closer to that of animal proteins (e.g. hydrolysis to improve solubility), but some processes that improve functionality also diminish amino acid bioaccessibility or bioactivity, creating negative nutritional consequences. Much more research and innovation are required to enhance the potential of plant proteins. In the short to medium term, nutritional and functional synergies between plant and animal proteins may offer a path to creating nutritious and attractive foods.

View PDFchevron_right
Comprehension and food analysis of a fermented mixture of animal proteins and vegetable proteins : influence on the physico-chemistry and the acceptability of the obtained products
Manhal Yousseef

2017

De nombreux problèmes ont été identifiés lors des tentatives d’incorporation de protéines végétales dans nos aliments. En particulier, les faux goûts, le goût et la texture ont été mis en évidence comme de véritables obstacles à l’acceptabilité des produits végétaux par les consommateurs. Le consommateur lui-même est aussi un déterminant important en ce qui concerne le terme « acceptabilité ». Donc, dans le but de développer un nouveau produit fermenté à base de protéines de pois deux volets ont été étudié : le produit et le consommateur. Afin de comprendre la physico-chimie et l’acceptabilité de produits fermentés à base de protéines de pois, plusieurs facteurs ont été étudiés dans des étapes successives tels que la culture, les allégations positives sur la santé et l’environnement, les cocktails de souches lactiques et les procédés de préparation. Dès les premiers tests sensoriels, il était clair qu’il ne serait pas facile de convaincre les consommateurs de consommer des produits ...

View PDFchevron_right
Amino Acids, Peptides and Proteins
Ferenc Hudecz

ELECTROPHORESIS, 2013

Objectives: I. Know the general structure of an α amino acid. II. Define the ionic / pH properties of amino acids. A. Conditions where the amino acid is a zwitterion. B. Conditions where the amino acid is at its isoelectric point. 1. How to calculate the isoelectric point of an amino acid given the pKa's of the ionizable groups. C. Conditions where the amino acid is in its cationic form. D. Conditions where the amino acid is in its anionic form. III. Classify a given amino acid as hydrophobic, polar and uncharged, polar with a negative charge (acidic) or polar with a positive charge (basic). A. Subclassifications 1. Aromatic amino acids. a) Properties conferred to proteins by the presence of these amino acids. 2. Sulfur containing amino acids. IV. Amino acids with a chiral carbon (tetrahedral stereocenter) in their structure. A. D / L enantiomeric forms versus R / S enantiomeric forms. V. Describe the structure of the peptide bond. VI. Describe the primary structure of proteins. A. Conditions where peptides and/or proteins are at its isoelectric point. B. Conditions where peptides and/or proteins are in a cationic form. C. Conditions where peptides and/or proteins are in an anionic form. VII. Classification according to size. A. Peptides B. Oligopeptides C. Polypeptides D. Proteins 1. Monomeric Proteins 2. Multimeric Proteins a) Homomultimeric Proteins b) Heteromultimeric Proteins c) Subunits VIII.Be familiar with the convention for drawing the structure and/or writing the amino acid sequence of peptides, oligopeptides, and proteins. IX. Classification of proteins based upon biological function. kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk The α Amino Acids As the name implies, amino acids contain a carboxylic acid group and an amino group. If this was the only criteria for a biologically active amino acid, there would be thousands of possible amino acids. The 20 amino acids found in nature are called alpha (α) amino acids based upon an archaic system of carboxylic acid nomenclature. In this system the carboxyl carbon is carbon 1 and the carbon adjacent to it (carbon 2) is

View PDFchevron_right
Proteins  Occurrence and general properties of amino acids,  peptides and proteins present in food Effect of pH and charge on amino acids, peptides and  Solubility of proteins proteins  Chemical reactions and physical changes occurring with  Effects of processing on properties of proteins free amino acids and proteins Amino Acids  Building blocks – Monomeric units of proteins  The monomer unit of proteins •R is the side chain. •One of 20 different chemical compounds •Some R-groups are acid (other alkali) •Some R-groups are water Chiral carbon (L- series) soluble (others are not) Proteins  Building blocks ● Amino acids – 20 amino acids Amino Acids Occurrence and general properties  >300 different amino acids identified - only ± 20  Amino acids contain an amino group (-NH2) and a carboxyl a.a commonly present in protein  Attached to the α-carbon next to a side chain group (-COOH)  Asymmetrical α-carbon making stereoisomerism and hydrogen atom possible – all in protein except glycine  Optically active  Chiral centre results in the L- and D-  Only L-amino acids – in proteins enantiomers Amino Acids – side chains  Differ - different properties and sizes  Three groups classification  A.A with polar (hydrophilic) charged side chains  A.A with polar (hydrophobic) non-charged side  A.A with non-polar non-charged side chains chains Classification of amino acids occurs according to their side chain Amino Acids Classification of amino acids occurs according to their side chain Amino Acids  Uncharged.  Aliphatic. Polar Non-Polar Ser, Thr, Ala, Ile, Leu, Asn, Gln, Cys Met, Pro, Val  Positive (basic). Arg,  Aromatic. Phe, Trp, Tyr Lys, His  Negative (acidic). Asp, Glu, Example Amino Acids Alanine Phenylalanine Glutamic acid Peptide Bonds  Peptides (and proteins) are sequences of amino acids that are linked to each other by a peptide bond. ● N-terminal amino acid - an amino acid with a free a-amino group on one end of the sequence ● C-terminal amino acid - an amino acid with a free a-carboxyl group at the other end Peptide Bonds  Condensation of a-COOH group of one amino acid with the a-NH2 group of another amino acid  removal of a water molecule ● Resultant structure – one a-NH2 group on the N-terminal amino acid and one a-COOH group on the C-terminal present in a peptide or protein molecule ● Structure of peptides and proteins from the N- terminal to the C-terminal Nomenclature  Number of amino acids – di, tri, tetrapeptides ● Protein – larger peptide (polypeptide)  Hydrolysis of proteins – breakdown of peptide bonds ● Peptide formation – protein hydrolysates ● Biological function e.g. anti-microbial peptides ● Functionality changes ● Protein size and folding ● Post translation hydrolysis – protease enzyme ● Disulphide bridge Disulfide Bonds C SH H2 HS C H2  Two cysteine molecules under oxidizing  Intermolecular or conditions [O] intramolecular cross- link C S S C H2 H2 Proteins  Consist of amino acids ● Difference in relative abundance in proteins  Structure and the properties of proteins depends ● Number of amino acids (length of the peptide chain) ● Composition of a.a (sequence) e.g. hydrophobic a.a and solubility Protein Structure . 20 Amino Acids Coded in DNA Primary Secondary Self assembly to a single (native) structure. Depends on primary structure and solution conditions Tertiary ( Quaternary ) Common in foods. Many non- native forms depending on protein structure, solution Denatured conditions (& history) and ingredient interactions Protein structure  Primary structure - a.a sequence – order of a.a in the  Secondary structure - non-covalent interactions of part chain of sequence – folding in repetitive spatial structures ● the a-helix, the b-sheet¸ and the random coil ● Formation of hydrogen bonds between peptide bonds via carbonyl oxygen atoms and amide  Tertiary structure – 3D structure of folded peptide hydrogen atoms ● Defines how the different elements of the secondary structure are oriented relative to each  Quaternary structure - way that the different other in 3D space polypeptide chains are associated ● Proteins formed by several polypeptide chain a-Helix  N-H to C=O hydrogen bonds in 4th succeeding  Hydrogen bonds A.A.  Typically parallel to axis amphiphilic b-Sheet  C=O and N-H perpendicular to chain form inter-segment H-  Parallel or antiparallel bonds  b-strands typically 5-15  More stable than a- A.A. helix b-sheet Protein Folding Hydrophobic amino acids Peptide chain Tertiary Structure Types of Tertiary Structure Classification based on size/conformation Globular Disordered/random coil Fibrous Many insoluble amino Interacts well with water acids, protein tends to Strong secondary and takes up a random minimize structure allows configuration surface/volume ratio protein to retain a neither globular nor non-spherical shape Solubility based on fibrillar – form micelles – not water soluble solvent  Other classification based on solubility – Prolamins, glutelins, albumins and globulins Quaternary Structure Folded protein unable to Dimerized protein shields the contain some hydrophobic hydrophobic amino acids residues from water Structural forces in protein folding and stability  Primary structure stabilised by covalent bonds - higher structures are stabilised mostly by non- covalent bonds ● Di-sulphide bond exception – tertiary and quartenary structure stabilisation Effect of pH on the charge of amino acids  Acidic and basic character ● carboxyl group (-COOH) and amino group (-NH2)  Peptides - also exhibit acid/base character ● Contribution of N-terminal (NH2-group)and C-terminal COOH-group VS amino acid side chains ● Depend on the length of chain ● longer peptide - less the contribution of the terminals  Overall charge of a.a - dissociation constants (pK) ● pH = pK the acid (or base) is exactly 50% protonated ● At pH << pK the acid (or base) is mostly in the protonated form (so COOH / NH3+) ● At pH >> pK the acid (or base) is mostly in the deprotonated form (so COO- / NH2)

Related papers

Chemical Modifications of Peptides and Their Impact on Food Properties
Fien Van Lancker

Chemical Reviews, 2011

|Chem. Rev. 2011, 111, 7876-7903 Chemical Reviews REVIEW free amino group positioned on the left. 2 The amino acids of the chain ends are denoted as N-terminal and C-terminal amino acids. This notation will also be used throughout this review. In addition, chirality of the molecules is not represented in the schemes and figures because, first, in many cases the chirality of the starting products was not specified in the corresponding publications and, second, the chirality of the starting products might not be conserved due to high processing temperatures. Because of the rather innovativeness of the subject, this review mainly covers literature from the last two decades. 2. IMPORTANCE OF PEPTIDES IN FOOD Initially, the discovery of oligopeptides as products of protein hydrolysis did not draw much attention. However, nowadays, peptides are highly valued in food because they influence the functional properties, affect the product taste, and exhibit biological activity. 1 Functional properties of peptides include solubilizing, emulsifying, gelling, and foaming properties. 5 Concerning taste properties, bitter-tasting peptides are described most extensively, while in fact, peptides may reveal all kinds of taste. Sweet, sour, salty, and umami tastes have also been reported. 1,5,6 Besides these five basic tastes, Japanese distinguish "kokumi", which has been described as continuity, mounthfulness, and thickness of taste. According to Ueda et al., 7 the peptide glutathione increases the kokumi flavor of umami solutions and a model beef extract. In addition, interaction of these different tastes can result in the formation of typical food flavors. For instance, the dry-cured ham flavor is very characteristic and, besides volatile compounds and amino acids, also peptides have been shown to contribute to this specific flavor. 8À10 The biological activity of peptides has been the subject of many studies, which have been compiled in multiple reviews. Biological activities include antimicrobial, 3,5,11,12 antioxidant, 3,12À15 antihypertensive (angiotensin converting enzyme [ACE] inhibitory), 3,12,13,16 antithrombotic, 3,13 hypocholesterolemic and hypotriglyceridemic, 3,13 antiobesity, 13 opioid agonist or antagonist, 3,5,12 immunomodulating, 3,5,12 cytomodulating, 3 mineral sequestering, 3,12 cytotoxic, 4 and allergenic 4,5 properties. Some peptides are multifunctional and can exert more than one of the effects mentioned. 3,13 Although most of the food peptides are degraded by the host during ingestion, digestion, and absorption, Sato et al. 17 demonstrated that some unmodified food-derived peptides are present in human blood.

View PDFchevron_right
Food chemistry
sau nguyenquang
View PDFchevron_right
Food protein functionality: A comprehensive approach
Allen Foegeding

Food Hydrocolloids, 2011

Food protein functionality has classically been viewed from the perspective of how single molecules or protein ingredients function in solutions and form simple colloidal structures. Based on this approach, tests on protein solutions are used to produce values for solubility, thermal stability, gelation, emulsifying, foaming, fat binding and water binding to name a few. While this approach is beneficial in understanding the properties of specific proteins and ingredients, it is somewhat restricted in predicting performance in real foods where the complexities of ingredients and processing operations have a significant affect on the colloidal structures and therefore overall properties of the final food product. In addition, focusing on proteins as just biopolymers used to create food structures ignores the biological functions of proteins in the diet. These can be beneficial, as in providing amino acids for protein synthesis or bioactive peptides, or these can be detrimental, as in causing a food allergic response. This review will focus on integrating the colloidal/polymer and biological aspects of protein functionality. This will be done using foams and gels to illustrate colloidal/polymer aspects and bioactive peptides and allergenicity to demonstrate biological function.

View PDFchevron_right
Structure-function relationships of food proteins: with an emphasis on the importance of protein hydrophobicity
Sher Shah

Journal of Agricultural and Food Chemistry, 1983

When hydrophobic parameters in addition to solubility were used, better correlations with protein functionality than using solubility alone were obtained. The hydrophobicity was measured fluorometrically before (So) and after (S,) unfolding protein samples. Significant correlations were found for emulsifying capacity, emulsion stability, and fat binding capacity of heat-denatured proteins with surface hydrophobicity (So) and solubility. For foaming capacity, an exposed hydrophobicity (S,) and viscosity played important roles; however, net charge was the most influential factor for foam stability. The S, and available SH-group content showed good correlations with thermal functional properties of proteins, e.g., heat coagulation, gelation, and thickening. Protein hydrophobicity, the hydrophile-lipophile balance (HLB) value of surfactants, and polarity of partition chromatography seem to be closely related. Ultimately, protein functionality is dependent on hydrophobic, electrostatic, and steric parameters of the proteins, which are all essential for defining the protein structure. More advanced data processing techniques, e.g., multivariate analysis, are needed for studying these relations. Elucidation of the mechanism of protein functionality has been attempted by many food protein chemists. The most recent monographs are the ones edited by Cherry (1981). However, the demand from the industry to predict the functionality of food proteins has not yet been met. In the case of general chemical compounds, it has been suggested that hydrophobic, electronic, and steric parameters can be independent variables for predicting their functional properties (Stuper et al., 1979). Although many papers have been published to emphasize the importance of hydrophobicity and hydrophobic interactions in protein functionality, the quantitative administration of this parameter is not facile. The quantitation of protein hydrophobicity can be an essential step for accurate prediction of protein functionality. The objective of this article is to discuss the relationship between hydrophobicity which effects structure and functionality of food proteins. However, the discussion is restricted to only quantitative data. Most general discussions without quantitative supporting data or with indirect evidence of the importance of hydrophobicity, e.g., data using dissociating agents, are therefore excluded. Solubility and Hydrophobicity Relationship. Solubility is an important property governing the functional behavior of proteins and their potential application to food processing. Denaturation implicates damages to functionality and is usually measured as a loss of solubility. Generally, soluble proteins possess superior functional attributes for most applications in food processing. However, there have been several contradictory reports showing that emulsifying properties and solubility are not closely correlated (

View PDFchevron_right
Physical Properties of Mixed Dairy Food Proteins
Charles Onwulata

International Journal of Food Properties, 2014

Foods may contain more than one type of protein, and food formulators sometimes combine different proteins for desired synergistic textural benefits. Egg albumin, fish protein isolate, or soy protein isolate were blended with calcium caseinate or whey protein isolate and mixed in water adjusted to pH 2.5, 6.8, and 9.0 at 25 or 60 • C. The effect of pH and temperature on solubility, viscosity, and the structure of the resulting gels were determined. The viscosity at the most soluble concentration at 25 • C were: egg albumin (175.2 mPa.s/35 wt%), fish protein isolate (2207.4 mPa.s/30 wt%), soy protein isolate (2531.5 mPa.s/10 wt%), calcium caseinate (1115.8 mPa.s/15 wt%), and whey protein isolate (161.2 mPa.s/35%). In mixed protein systems viscosity values were reduced. The values for calcium caseinate or whey protein isolate with egg albumin, at the protein level of 15 g/100 g were: calcium caseinate/egg albumin (10:5 wt%) 535.1 mPa.s and whey protein isolate/egg albumin (10:5 wt%) 8.7 mPa.s. Microscopy imaging revealed changes in protein aggregation clusters during heating of calcium caseinate, egg albumin, and whey protein isolate. Egg albumin acted synergistically to increase viscosity, while fish protein isolate acted antagonistically to reduce viscosity. This knowledge is useful to manufacturers who may seek to enhance food texture by blending different proteins.

View PDFchevron_right
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved