Food Proteins and Peptides

Emerging Biofunctions, Food and Biomaterial Applications

Chibuike C Udenigwe, Chibuike C Udenigwe

• Publisher: Royal Society of Chemistry
• Year: 2021
• ISBN:
  9781839163432
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

This book discusses the chemistry of food proteins and peptides and their relationship with nutritional, functional, and health applications.
Bringing together authorities in the field, it provides a comprehensive discussion focused on fundamental chemistries and mechanisms underpinning the structure-function relationships of food proteins and peptides. The functional and bioactive properties hinge on their structural features such as amino acid sequence, molecular size, hydrophobicity, hydrophilicity, and net charges. The book includes coverage of advances in the nutritional and health applications of protein and peptide modifications; novel applications of food proteins and peptides in the development of edible functional biomaterials; advances in the use of proteomics and peptidomics for food proteins and peptide analysis (foodomics); and the relevance of food protein and peptide chemistries in policy and regulation.
Research into the fundamental chemistries behind the functional, health and nutritional benefits is burgeoning and has gained the interest of scientists, the industry, regulatory agencies, and consumers. This book fills the knowledge gap providing an excellent source of information for researchers, instructors, students, food and nutrition industry, and policy makers.

CHAPTER 1

Food Protein Structures, Functionality and Product Development

IFEANYI D. NWACHUKWU^a AND ROTIMI E. ALUKO^*b, ^*c

^a Center for Nutrition and Healthy Lifestyles, School of Public Health, Loma Linda University, 24951 North Circle Drive, Loma Linda, CA 92350, USA ^b Department of Food and Human Nutritional Sciences, University of Manitoba, 190 Dysart Road, Winnipeg, Manitoba, R3T 2N2, Canada, ^c Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, 196 Innovation Drive, Winnipeg, Manitoba, R3T 2N2, Canada
^*E-mail: [email protected]

The structure of food proteins influences their function and hence their use in developing food products. Researchers have frequently employed enzymes to modify and study protein techno-functionality under different conditions and to enhance the biological functions or health-promoting properties of proteins. As more people continue to show interest not only in the nutritive aspect of food proteins but also in the sustainability of food processing and product development methods, there has been a growing effort by researchers and the food industry to provide food protein products that are consistent with the expectations of today's consumers. Not only is the use of green processing methods such as supercritical fluid extrusion, ohmic heating, pulsed electric field and high hydrostatic pressure on the increase, there is also heightened interest in innovative high-tech strategies for food delivery and controlled nutrient release such as micro- and nanoencapsulation. This chapter reviews the various sources of food proteins, including non-traditional sources such as algae and insects, the effects of various processing methods on food protein structure and functionality, novel delivery systems and technologies in food protein product development and the growing impact of consumers on product development, including the increasing consumption of and even preference for plant-based meat alternatives. It is concluded that although there are promising signs of increased use of sustainable processing methods and seemingly endless possibilities in the development of new food protein products, there are also challenges such as the microbiological and allergenic risks inherent in using members of the class Insecta for food.

1.1 Introduction

The unique combinations of biological, nutritional and functional properties in proteins make them important food ingredients with the capacity to provide a range of diverse and highly versatile products following processing.¹ Proteins contain amino acids, which provide essential nutritional support, and certain fractions such as whey and casein are good sources of functional proteins.^1,2 The ability of proteins in whey such as α-lactalbumin, β-lactoglobulin and bovine serum albumin to interact and form aggregates contributes to the techno-functional properties of protein products such as whey protein isolate and whey protein concentrate and therefore to their use in emulsions, gels, coatings, films and protein-based encapsulation materials.^1,3

To obtain pure proteins or to design food products that contain (added) proteins, it is necessary to separate the desired protein from unwanted proteins and non-protein components present in the starting material. With variations that depend on the protein raw material, the process of producing biofunctional protein hydrolysates and peptides from food proteins typically involves extracting crude proteins from the protein source using aqueous or organic solvents and centrifuging the extract to further purify and separate the isolated proteins from unwanted and often insoluble non-protein materials.⁴ Further purification steps may include dialyzing the supernatant of the protein extract against distilled water to remove residual salt and precipitate salt-soluble contaminants or treating the extract with dilute acid to initiate precipitation of the protein of interest (or that of the impure sediment) while leaving the impurities (or the desired protein) in solution.⁴ The proteins obtained from this kind of extraction and precipitation process are referred to as protein isolates and concentrates and could undergo additional purification based on their size, affinities for certain ligands, hydrophobicity and ionic properties in order to obtain a purer, more homogeneous protein product.⁴

The techno-functional properties of proteins such as their water- and oil-binding capacities, solubility and emulsification and foaming properties influence food processing, preparation and storage, in addition to contributing to the quality and organoleptic properties of foods.⁵ Since food processing can affect the techno-functional properties of proteins, a knowledge of the structural arrangement of proteins and the capacity of chosen processing methods to modify protein functionality is important not only to researchers but also to the chemical, pharmaceutical and food industries.⁵ In this chapter, we review various sources of food proteins, the capacity of structure to influence protein function, the use of enzymes to modify structure and thus function, emerging food protein processing methods, the influence of the consumer and ethical and sustainability considerations in shaping food protein product development.

1.2 Sources of Food Proteins

1.2.1 Plants

Food proteins and their component bioactive peptides have been isolated from a variety of plant foods, including cereals such as rice, maize, wheat, barley, oat and sorghum,^6,10 pseudocereals such as buckwheat, amaranth and quinoa,^9,11,12 pulses such as peas, chickpeas, lentils and kidney beans,^13,16 oilseed crops such as flaxseed, soybean, peanuts, sunflower, cotton, hempseed and sesame,^17,25 tuber crops such as potato,²⁶ edible seeds such as chia and pumpkin,^27,28 tree nuts such as almonds, chestnuts, pecans and walnuts^29,32 and by-products of fruits and vegetables such as peach, cherry, date and tomato seeds.³³ The wide distribution and heterogeneity of these plant protein sources not only demonstrate the structural diversity, abundance and diverse origins of plant food proteins but also the enormous potential for isolating novel peptides with various important bioactive properties from these plant protein sources. The isolation of proteins from plants distinctly differs from that of non-plant sources such as animals, fish and algae in not involving the additional steps required to remove vegetal non-protein materials such as fiber in addition to antinutritional factors such as enzyme inhibitors, saponins, uricogenic nucleobases, vicine, gossypol, metal chelators, convicine, cyanogenic glycosides and polyphenolics, all of which have the potential to limit protein availability and utilization.^34,37 Given their status as the staple foods in many regions of the world, certain cereals such as wheat, rice and maize are among the most important sources of plant proteins.³⁸ Although animal proteins are generally thought to be of higher quality than vegetal proteins, soybean protein is notable for being of extremely high quality [with a perfect protein digestibility-corrected amino acid score (PDCAAS) of 1.0], containing all the essential amino acids and being low in saturated fats.³⁸ In terms of food product development, various soy-derived foods such as miso, tofu, soy yogurt, yuba, toasted soy protein powders, natto, soy sauces, soy burger, tempeh, soy milk and soy-based sausages have not only achieved great commercial success but also are widely consumed by consumers who see them as nutritious and healthy alternatives to proteins from animal sources.^39,41

1.2.2 Animals

Animal proteins are an important and often essential component of various food products where their physicochemical and biological characteristics serve to enhance the nutritional, organoleptic and even health-promoting properties of those foods.⁴² The high nutritional quality and excellent physicochemical properties of the dairy proteins casein and whey are central to their wide use in many food products. From infant formulas, sour cream, yogurt, marmalade and coffee whiteners containing whey protein concentrates to mayonnaise, ice cream, desserts, fabricated meats, pizza cheese, whipping cream and salad dressings containing casein and/or egg-white proteins,^2,42 examples of widely consumed food products composed of integral animal protein ingredients abound. Similarly, the physicochemical and structural properties of muscle meat proteins are critical to their use in preparing surimi, a crude myofibrillar protein concentrate, derived from under-utilized marine fishes such as mackerel, croaker, Pacific whiting and Alaska pollock and used for making seafood analogs such as lobster and imitation crab meat.⁴³ The biological properties of protein hydrolysates and peptides of animal origin have also contributed to their use in the food industry for the formulation of medical foods designed to manage food allergies and control conditions such as cystic fibrosis, liver disease, Crohn's disease and phenylketonuria.⁴⁴ Bioactive hydrolysates and peptides have been derived from a myriad of diverse animal and marine protein sources and protein by-products including salmon, oyster, milk, eggs, snow crab, seahorse, giant squid, sea urchin, shrimp, half-fin anchovy, blood clam muscle, jellyfish collagen, rockfish gelatin, cheese, chicken breast muscle, dry-cured ham, tuna cooking juice, abalone viscera, beef, Kacang goat and tunicate, as previously reviewed.^45,49 Such food protein hydrolysates and bioactive peptides of animal origin have been found to possess a range of health-promoting properties, including hypolipidemic, antioxidant, antiproliferative, immunomodulatory, antimicrobial and antihypertensive activities.⁵⁰

1.2.3 Insects

Although the heightened demand for high-quality food proteins and growing food security concerns in recent years have contributed to the increased use of proteins from insects for both food and feed,⁵¹ the consumption of insects, or entomophagy, is hardly a novel idea given that insects were a part of the diet of the evolutionary precursors of humans.⁵² It is estimated that up to 2000 different insect species are edible and could be consumed at different stages of development, such as egg, larva or pupa, with...