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- Herausgeber: John Wiley & Sons
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- Sprache: Englisch
LENTILS Understand the future of plant protein with this comprehensive overview Lentils are one of the oldest and most widely cultivated crop species in the world and a leading global source of protein, carbohydrates, and dietary fiber, as well as numerous micro-nutrients. In recent years, they have emerged as a leading candidate to form the basis of non-meat protein substitutes, a skyrocketing industry with immense climate and public health implications. There has never been a more urgent need to understand the cultivation and use of these flexible, resource-rich crops. Lentils provides a comprehensive overview of every stage in the lentil production chain, from cultivation to processing to sale to consumption. It focuses particularly on pre- and post-harvest processing, alerting readers to the possibilities of lentils in a newly health and environmentally conscious global food marketplace. The result is a thorough, highly accessible, and navigable introduction to a vital subject. The reader can also find: * Detailed coverage of lentils including global production/trade, breeding practices, value-addition, nutrition, consumption trends, and quality assessment * Innovative three-part structure to facilitate reader navigation * Dedicated chapters on lentil-based meat analogs, engineering properties, and innovative processing technologies The book can be used as a useful reference for academics and researchers who are working in the fields of food science, food technology, food process engineering, and applied nutrition, as well as for food industry professionals and government regulators with an interest in food production, food security, and the global food market dynamics.
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Table of Contents
Cover
Title Page
Copyright Page
Preface
List of Contributors
Part I: Overview, Breeding Practices, Postharvest Handling, and Storage
1 An Overview of Lentil Production, Trade, Processing, and Nutrient Profile
1.1 Introduction
1.2 Lentil Plant and Seed Characteristics
1.3 Global Production and Trade
1.4 Preharvest and Preharvest Quality Management
1.5 Nutritional Profile and Health Benefits
1.6 Lentil Processing and Emerging Trends
1.7 Role of Lentil in Sustainable Agriculture Systems
1.8 Research on Lentil Crop
1.9 Conclusion
References
2 Recent Advances in Lentil Genetics, Genomics, and Molecular Breeding
2.1 Introduction
2.2 Lentil Genetic Resources
2.3 Lentil Classical Genetics and Its Application in Breeding
2.4 Breeding Opportunities Offered by Development of Genomic Resources
2.5 Comparative and Functional Genomics
2.6 Conclusions
References
3 Preharvest Quality Management, Postharvest Handling, and Consumption Trends of Lentils
3.1 Introduction
3.2 Preharvest Quality Management
3.3 Postharvest Handling, Storage, Grading, and Packaging
3.4 Quality Grading and Packaging
3.5 Role in World Food Security
3.6 Consumption Trends
3.7 Conclusion
References
Part II: Processing, Physical and Functional Properties, and Food and Nonfood Applications
4 Value‐Added Processing of Lentils and Emerging Research Trends
4.1 Introduction
4.2 Value‐Added Lentil Processing
4.3 Emerging Research and Development Trends
4.4 Development of Lentil‐Based Products
4.5 Conclusion
References
5 Milling and Fractionation Processing of Lentils
5.1 Introduction
5.2 Milling Process
5.3 Pulse Flour
5.4 Fractionation Methods
5.5 Pulse Fractions
5.6 Conclusions
References
6 Functional Properties of Lentils and Its Ingredients in Natural or Processed Form
6.1 Introduction
6.2 Nutri‐Functional and Health‐Promoting Properties
6.3 Techno‐Functional Properties
6.4 Effect of Processing on Quality Characteristics of Lentil Ingredients
6.5 Food Applications of Lentil‐Based Ingredients
6.6 Encapsulation or Edible/Biodegradable Material
6.7 Conclusion
References
7 Rheological Properties of Lentil Protein and Starch
7.1 Introduction
7.2 Rheological Measurement Techniques Related to Lentils
7.3 Rheological Properties of Lentil Constituents
7.4 Lentil Protein‐Based Emulsion Rheology
7.5 Interfacial Rheology of Lentil Protein‐Based Emulsion
7.6 Rheological Properties of Lentil Protein–Starch Composites
7.7 Conclusions
References
8 Pasting, Thermal, and Structural Properties of Lentils
8.1 Introduction
8.2 Pasting Properties of Lentils
8.3 Thermal Analysis of Lentils
8.4 Scanning Electron Microscopy (SEM)
8.5 Fourier Transform Infrared (FTIR) Spectroscopy
8.6 X‐ray Diffraction (XRD) Patterns
8.7 X‐ray Tomography
8.8 Nuclear Magnetic Resonance (NMR)
8.9 Atomic Force Microscopy (AFM)
8.10 Conclusions
References
9 Lentil Protein
9.1 Introduction
9.2 Extraction Techniques for Plant Protein
9.3 Techno‐Functional Properties of Lentil Protein
9.4 Lentil Protein‐Based Meat Analogues and Extenders
9.5 Consumer Preferences and Willingness to Pay for Lentil Protein Food
9.6 Quality of Lentil Protein‐Based Meat Analogue
9.7 Future Trends and Suggestions for Lentil Protein‐Based Meat Analogue
9.8 Market Status and Prospect of Lentil Protein‐Based Meat Analogues
9.9 Conclusion
References
10 Utilization of Lentils in Different Food Products
10.1 Introduction
10.2 Bakery Products
10.3 Extruded Products
10.4 Dairy Products
10.5 Meat Products
10.6 Salad Dressing
10.7 Conclusion
References
11 Nonfood Applications of Lentils and Their Processing By‐products
11.1 Introduction
11.2 Nonfood Applications of Lentils and Their Processing By‐products
11.3 Conclusions
References
12 Innovative Processing Technologies for Lentil Flour, Protein, and Starch
12.1 Introduction
12.2 High‐Pressure Treatment
12.3 HP‐Treatment to Lentil Ingredients
12.4 Microwave (MW) and Radio‐Frequency (RF) Heating
12.5 Ionizing Irradiation (IR)
12.6 Ultrasound (US) Processing
12.7 Ozone Treatment
12.8 Ultrafiltration (UF) and Isoelectric Precipitation (IEP)
12.9 Ultraviolet (UV) and Visible Light Treatment
12.10 Pulsed Light Treatment
12.11 Conclusions
References
Part III: Nutrition, Antinutrients, Sensory Properties, and Global Consumption Trends
13 Nutritional Profile, Bioactive Compounds, and Health Benefits of Lentils
13.1 Introduction
13.2 Composition and Nutrient Profile
13.3 Processing Effect on Chemical and Nutritional Composition
13.4 Health Benefits of Lentils
13.5 Conclusion
References
14 Antinutritional Factors in Lentils
14.1 Introduction
14.2 Lentil Protein and Amino Acid Profile
14.3 Antinutritional Factors (ANFs) in Lentils and Their Properties
14.4 Nutritional Significance and Implications of Selected ANFs
14.5 Effect of Processing Methods on ANFs
14.6 Health Implications of ANFs
14.7 Conclusion
References
15 Sensory Properties of Cooked Lentils and Lentil‐Based Products
15.1 Introduction
15.2 Impact of Lentil Addition on Sensory Properties of Lentil‐Based Food Products
15.3 Physical Characteristics of Dough and Sensory Quality of Lentil‐Based Baked Products
15.4 Conclusion
References
16 Global Consumption and Culinary Trends in Lentil Utilization
16.1 Introduction
16.2 Global Production and Consumption Trends
16.3 Utilization of Lentils in Diverse Cuisines
16.4 Regional Lentil Cuisines Worldwide
16.5 Potential for Enhancing Market Opportunities for Lentils
16.6 Conclusion
References
Index
End User License Agreement
List of Tables
Chapter 1
Table 1.1 Attributes of different lentil types.
Table 1.2 Top 10 lentil producing, exporting, and importing countries in 202...
Table 1.3 Composition of lentil compared to major cereals.
Table 1.4 Composition of raw and cooked lentils (per cup).
Chapter 3
Table 3.1 Weeks of lentils' storage at the specified grain moisture and stor...
Table 3.2 Storage‐induced defects and their impact on legume quality.
Table 3.3 US Grades and grade requirements of lentils (% allowable limits)....
Table 3.4 Range of lentil‐based pastas by the lentil type, product shape, an...
Table 3.5 Common lentil market classes and consuming countries.
Chapter 4
Table 4.1 Quality characteristics and food product applications of green and...
Table 4.2 Effect of different methods on the nutritional quality of lentils....
Table 4.3 Overview of functional properties and uses of lentil flour (LF) in...
Chapter 6
Table 6.1 Techno‐functional properties of lentil protein isolates (LPIs).
Table 6.2 Effect of fermentation on nutri‐ and techno‐functional characteris...
Table 6.3 Effect of hydrothermal processing (boiling) on nutri‐ and techno‐f...
Table 6.4 Effect of extrusion processing on nutri‐ and techno‐functional cha...
Chapter 7
Table 7.1 Herschel‐Bulkley model parameters for lentil doughs at 110 °C.
Table 7.2 Rheological model parameters for three Australian lentil starch di...
Table 7.3 Creep properties of lentil starch gels at selected concentration....
Chapter 8
Table 8.1 Pasting properties of lentil starch suspensions of selected cultiv...
Table 8.2 Pasting properties of lentil starch (LS), lentil protein (LP), and...
Table 8.3 Pasting properties of micronized lentil seed flours.
Table 8.4 Thermal properties of lentil flours and their modifications.
Table 8.5 Thermal properties of isolated lentil starches and modified starch...
Table 8.6 Protein denaturation temperatures of lentils.
Chapter 9
Table 9.1 Commonly used protein extraction techniques for lentil flour.
Table 9.2 Techno‐functional properties of lentil protein.
Table 9.3 Lentil protein‐based meat alternative products.
Table 9.4 Protein digestibility‐corrected amino acid score (PDCAAS) for sele...
Chapter 10
Table 10.1 The recent studies about meat products supplemented with lentil i...
Chapter 11
Table 11.1 Major nutritional profile of raw lentils (g/100 g dry weight basi...
Chapter 12
Table 12.1 Application of high‐pressure treatment on lentil ingredients and ...
Table 12.2 Influence of high‐pressure treatment on pasting properties of len...
Table 12.3 Dielectric properties of lentil flour at selected frequencies, mo...
Chapter 13
Table 13.1 Composition of raw, sprouted, and cooked (boiled, no salt) lentil...
Table 13.2 The essential amino acids content (g/100 g) of lentil proteins co...
Table 13.3 Physiological effects of bioactive compounds in legumes.
Table 13.4 Value‐added processing of lentils and typical end‐products.
Table 13.5 Changes in the nutritional and non‐nutritional constituents of le...
Chapter 14
Table 14.1 Genetic variation for protein concentration in cultivated lentils...
Table 14.2 Amino acid profile of cultivated lentil genotypes.
Table 14.3 Trypsin inhibitor activity (TIA) in different legumes.
Table 14.4 Effect of processing on the saponin content of lentils.
Table 14.5 Health benefits of bioactive compounds found in legumes.
Chapter 15
Table 15.1 Summary of sensory testing studies carried out on lentils and len...
Table 15.2 Summary of sensory testing studies carried out on lentils and len...
Table 15.3 Summary of sensory testing studies carried out on lentils and len...
Table 15.4 Summary of sensory testing studies carried out on lentils and len...
Table 15.5 Summary of sensory testing studies carried out on lentils and len...
Table 15.6 Summary of sensory testing studies carried out on lentils and len...
Table 15.7 Summary of sensory testing studies carried out on lentils and len...
Table 15.8 Impact of replacing wheat with different percentages of lentil fl...
Chapter 16
Table 16.1 Lentil‐based cuisines around the world.
Table 16.2 Comparison of macronutrients, water content, and calories derived...
List of Illustrations
Chapter 1
Figure 1.1 Whole lentil seeds and split/dehulled
dhal
.
Figure 1.2 Word production and cultivated area of lentils (1991–2021).
Figure 1.3 Percent share of lentil production by region in 2021.
Figure 1.4 General mechanism for symbiotic nitrogen fixation in legume root ...
Chapter 2
Figure 2.1 A schematic overview of genomics‐based breeding in lentils.
Chapter 3
Figure 3.1 Postharvest unit operations for handling and cleaning of lentils....
Figure 3.2 Interaction of grain moisture, storage temperature, and equilibri...
Figure 3.3 Temperature and relative humidity (RH) measurement tools used dur...
Chapter 4
Figure 4.1 Flow diagram of lentil processing methods and end‐product.
Figure 4.2 Diverse application of legume protein, starch, and fiber ingredie...
Chapter 5
Figure 5.1 Schematic representation of wet fractionation process.
Figure 5.2 Schematic representation of dry fractionation process.
Figure 5.3 (A) Schematic drawing of cells of pea and the fragments after mil...
Figure 5.4 The dry and wet fractionation methods for pulse–protein extractio...
Figure 5.5 Dry fractionation process of pulses.
Figure 5.6 Simplified biorefinery process flow diagram for simultaneous reco...
Figure 5.7 Sankey diagrams of dry fractionation, wet fractionation and hybri...
Chapter 7
Figure 7.1 Shear stress–shear rate rheograms for the lentil dough at 110 °C....
Figure 7.2 Influence of particle size on the peak complex viscosity of lenti...
Figure 7.3 Shear stress–shear rate plot of typical lentil starch dispersions...
Figure 7.4 The 2nd‐order reaction kinetics for lentil starch dispersion (25 ...
Figure 7.5 Applicability of time–temperature superposition (TTS) for neat st...
Figure 7.6 Creep and recovery curves for lentil starch gels (triangle: whole...
Figure 7.7 Rheograms of lentil proteins as influenced by high‐pressure and e...
Figure 7.8 Rheological properties of LPI suspension (10%, w/v) for the forma...
Figure 7.9 Change in
G
′
and
G
″
as a function of % strain for nan...
Figure 7.10 Effect of temperature (60° and 10 °C) on mechanical spectra of L...
Chapter 8
Figure 8.1 Pasting properties of lentil flours of different cultivars.
Figure 8.2 SEM micrographs for lentil flour samples. (a) Indian LF 210‐μm fr...
Figure 8.3 SEM pictures of lentil protein isolate powders: (a and b) freeze‐...
Figure 8.4 Microstructures and appearance for LPI gels at different pH level...
Figure 8.5 SEM micrographs of freeze‐dried gels of (a and b) lentil protein ...
Figure 8.6 Deconvoluted FTIR spectra in the amide 1
′
absorption region...
Figure 8.7 X‐ray diffraction patterns of isolated lentil starches.
Figure 8.8 3D cross‐sectional microstructure of red lentil extrudates at (a)...
Figure 8.9
13
C CP/MPS NMR spectra of resistant starch from processed and unt...
Figure 8.10 The AFM images of lentil proteins during fibril formation (C1: 0...
Figure 8.11 AFM images of lentil protein concentrate (LPC) and generated bio...
Chapter 9
Figure 9.1 Lentil as a sustainable source of protein for developing meat ana...
Figure 9.2 Schematic diagram for wet protein extraction from food legumes....
Figure 9.3 Schematic diagram for dry protein fractionation from food legumes...
Figure 9.4 Schematic diagram of the enzyme‐assisted aqueous extraction of pr...
Figure 9.5 Structuring technique for meat analogue products: (a) extrusion; ...
Figure 9.6 The economic valuation techniques for goods and services.
Chapter 10
Figure 10.1 SEM micrographs (x30) of cake samples baked in different ovens. ...
Chapter 11
Figure 11.1 Production (hectares) and harvested area (tonnes) of lentils in ...
Figure 11.2 Nonfood applications of lentils.
Figure 11.3 Potential of lentils as an encapsulating agent with desirable pr...
Figure 11.4 Fabrication process of lentil‐based packaging materials.
Figure 11.5 Potential applications of lentil‐based additive ingredients in d...
Chapter 12
Figure 12.1 Laboratory scale and commercial vertical designed high‐pressure ...
Figure 12.2 Changes in the viscoelastic properties of lentil flour dispersio...
Figure 12.3 Scanning electron micrographs of pressure‐treated lentil starch ...
Figure 12.4 FTIR spectra (a) and X‐ray diffraction (b) of high‐pressure‐trea...
Figure 12.5 SDS‐PAGE of lentil protein isolates (LPI) and hydrolysates (LPH)...
Figure 12.6 Microwave fluidized‐bed system for drying and disinfection of pa...
Figure 12.7 Micrographs (left: ×1300 magnification and right: ×3000 magnific...
Figure 12.8 Experimental set‐up ozone generation unit.
Chapter 13
Figure 13.1 A comparison of protein, carbohydrate, total lipids, and ash con...
Figure 13.2 Content of amino acids in raw whole lentils.
Chapter 14
Figure 14.1 Schematic diagram of mercolectin, hololectin, chimerolectin, and...
Chapter 16
Figure 16.1 Top 10 countries with the highest daily per capita calorie consu...
Figure 16.2 Typical preparatory steps used in culinary applications of lenti...
Guide
Cover Page
Title Page
Copyright Page
Preface
List of Contributors
Table of Contents
Begin Reading
Index
Wiley End User License Agreement
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Lentils
Production, Processing Technologies, Products, and Nutritional Profile
Edited by
Jasim Ahmed
Food and Nutrition Program
Environment and Life Sciences Research CenterKuwait Institute for Scientific ResearchSafat, Kuwait
Muhammad Siddiq
Food Science Consultant
Windsor, ON, Canada
Mark A. Uebersax
Department of Food Science and Human Nutrition
Michigan State UniversityEast Lansing, MI, USA
This edition first published 2023© 2023 John Wiley & Sons Ltd
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The right of Jasim Ahmed, Muhammad Siddiq, and Mark A. Uebersax to be identified as the editorial material in this work has been asserted in accordance with law.
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Preface
Lentils are one of the oldest crop species in the world, produced in more than 45 countries, and consumed widely in various forms. Legumes, like lentils, are an excellent source of protein, low digestible carbohydrates, dietary fiber, and selected minerals and vitamins. Recent consumer interest in plant proteins as a substitute for meat proteins has been dramatic. Thus, food processors, nutrition and health professionals, and policymakers have directed an increased attention to lentils as a potential candidate for meat‐alternate protein source. Plant breeding experts endeavor to exploit the latest genetic tools and biotechnological approaches to improve the yield and quality of lentils as a sustainable crop with demonstrated environmental benefits. Innovative lentil breeding methods can potentially improve the economic return for the farmers and bring additional proteins to the food supply chain. Lentil continues to be one of the most important food legumes in the world due to its nutrient‐dense properties. The superior functionality of lentils provide an excellent source of natural products from which a wide range of value‐added products and by‐products can be prepared. The extraction of a huge amounts of proteins from lentils results in an equal or greater amount of starch in the production facility. Lentil starch can also be exploited for nonfood uses for expanding lentils use beyond food applications. Technological advancements in lentil‐based product formulations can improve functionality, remove antinutritional factors, and produce healthy food products.
The book is unique in that it provides topical coverage across lentil value‐chain, from breeding methods and postharvest handling to global consumption trends, value‐added processing, nonfood uses, nutritional significance, functional properties, and sensory attributes. This book should serve as a useful reference for food scientists, food technologists, food industry professionals, and graduate students. In addition, nutritionists, dietitians, and policy makers and nongovernmental organization working in the food security and international development areas can equally benefit from information presented in this book. The contents of the book have been arranged in three separate sections so that readers can find their choice of subjects easily. The first section, Overview, Breeding Practices, Postharvest Handling, and Storage contains three chapters describing global production and trade, breeding and genetics, and postharvest handling and storage of lentils. The second section, Processing, Physical and Functional Properties, and Food and Nonfood Applications, has nine chapters. Particular attention is given to the nutritional and antinutritional factors of lentils, value‐added processing, functional properties including rheological and pasting properties, the development of lentil‐based snack products, and the role of legume proteins in developing emulsions for food and drug delivery. The milling of lentils is included in the book to apprise the reader of the processes associated with isolating major components and the importance of size reduction. The most relevant trend in today's world is the meat analog using legume/lentil proteins, which is covered in a dedicated chapter. Applications of innovative processing technologies are included in a complete chapter focusing on details of high‐pressure processing and dielectric heating. The third section, Nutrition, Antinutrients, Sensory Properties, and Global Consumption Trends, has four chapters, which cover nutritional profiles, antinutritional factors in legumes/lentils, sensory evaluation, global consumption, and culinary trends in lentils. Over 40 researchers with diverse subject–matter background have contributed to this book.
The editors acknowledge many individuals for their support from conception through final development of this book. Foremost is our sincere thanks and gratitude to all authors for their contributions and for bearing with us during the review and finalization process of their chapters. Thanks are due to Amaan Thasin for providing library and literature search support. We are grateful to our family members for their understanding and support enabling us to complete this work. The editors thank Wiley for their diligent support in publishing this book.
Jasim Ahmed
Muhammad Siddiq
Mark A. Uebersax
List of Contributors
George O. AbongDepartment of Food Science, Nutrition & Technology, University of Nairobi, Kangemi, Kenya
Jasim AhmedFood and Nutrition Program, Environment and Life Sciences Research Center, Kuwait Institute for Scientific Research, Safat, Kuwait
Tahira M. AliDepartment of Food Science and Technology, University of Karachi, Karachi, Pakistan
Nandika BandaraDepartment of Food and Human Nutritional Sciences, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, MB, Canada
and
Richardson Centre for Food Technology and Research (RCFTR), University of Manitoba, Winnipeg, MB, Canada
Santanu BasuDepartment of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
Fatema H. BrishtiDepartment of Food Technology, Faculty of Food Science & Technology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
Natasha A. ButtDepartment of Biomedical Engineering, Faculty of Engineering, Science, Technology and Management, Ziauddin University, Karachi, Pakistan
Anup ChandraDivision of Crop Protection, ICAR‐Indian, Institute of Pulses Research, Kanpur, UP, India
Sanju Bala DhullDepartment of Food Science and Technology, Chaudhary Devi Lal University, Sirsa, Haryana, India
Thilini DissanayakeDepartment of Food and Human Nutritional Sciences, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, MB, Canada
and
Richardson Centre for Food Technology and Research (RCFTR), University of Manitoba, Winnipeg, MB, Canada
Madhuresh DwivediDepartment of Food Process Engineering, National Institute of Technology, Rourkela, Orissa, India
Ayca A. EmirDepartment of Food Technology, Faculty of Canakkale Applied Sciences, Çanakkale Onsekiz Mart University, Canakkale, Turkey
Tadesse S. GelaDepartment of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada
Debjyoti S. GuptaDivision of Crop Improvement, ICAR‐Indian Institute of Pulses Research, Kanpur, UP, India
Nazimah HamidDepartment of Food Science and Microbiology, Auckland University of Technology, Auckland, New Zealand
Abid HasnainDepartment of Food Science and Technology, University of Karachi, Karachi, Pakistan
Lilian D. KaaleDepartment of Food Science and Technology, University of Dar es Salaam, Dar es Salaam, Tanzania
Kevin KantonoDepartment of Food Science and Microbiology, Auckland University of Technology, Auckland, New Zealand
Kulwinder KaurDepartment of Processing and Food Engineering, Punjab Agricultural University, Ludhiana, India
Preetinder KaurDepartment of Processing and Food Engineering, Punjab Agricultural University, Ludhiana, India
Semin O. KeskinDepartment of Food Processing, Kocaeli University, Kocaeli, Turkey
Hamid KhazaeiNatural Resources Institute Finland (Luke), Helsinki, Finland
and
Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
Joyce KinaboDepartment of Human Nutrition and Consumer Sciences, Sokoine University of Agriculture, Morogoro, Tanzania
Gaurav KumarDepartment of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, India
Jitendra KumarDivision of Crop Improvement, ICAR‐Indian Institute of Pulses Research, Kanpur, UP, India
Ye LiuDepartment of Food Science and Microbiology, Auckland University of Technology, Auckland, New Zealand
Tareq MzekSchool of Business and Economics, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
Harshani NadeeshaniDepartment of Food and Human Nutritional Sciences, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, MB, Canada
and
Richardson Centre for Food Technology and Research (RCFTR), University of Manitoba, Winnipeg, MB, Canada
Najmun NaharDepartment of Food Science, Maulana Abul Kalam Azad University of Technology, Haringhata, West Bengal, India
Charlotte Oduro‐YeboahFood Technology Research Division, CSIR – Food Research Institute, Accra, Ghana
Priya PalDivision of Food Science and Postharvest Technology, ICAR‐Indian Agricultural Research Institute, New Delhi, India
Natalie PettittDepartment of Food Science and Microbiology, Auckland University of Technology, Auckland, New Zealand
Pramod K. PrabhakarDepartment of Food Science and Technology, National Institute of Food Technology Entrepreneurship and Management, Kundli, India
Elenjikkal J. RifnaDepartment Food Process Engineering, National Institute of Technology, Rourkela, Odisha, India
Shalini G. RudraDivision of Food Science and Postharvest Technology, ICAR‐Indian Agricultural Research Institute, New Delhi, India
Nazamid SaariDepartment of Food Science, Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
Muhammad SiddiqFood Science Consultant, Windsor, ON, Canada
Akanksha SinghAmity Institute of Organic Agriculture, Amity University, Noida, India
Rabiha B. SulaimanDepartment of Food Technology, University Putra Malaysia (UPM), Serdang, Selangor, Malaysia
Gulum SumnuDepartment of Food Engineering, Middle East Technical University, Ankara, Turkey
Rahul K. ThakurDivision of Food Science and Postharvest Technology, ICAR‐Indian Agricultural Research Institute, New Delhi, India
Mark A. UebersaxDepartment of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, USA
Eda YildizDepartment of Food Engineering, Middle East Technical University, Ankara, Turkey
Part IOverview, Breeding Practices, Postharvest Handling, and Storage
1An Overview of Lentil Production, Trade, Processing, and Nutrient Profile
Mark A. Uebersax1, Muhammad Siddiq2, and Lilian D. Kaale3
1 Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, USA
2 Food Science Consultant, Windsor, ON, Canada
3 Department of Food Science and Technology, University of Dar es Salaam, Dar es Salaam, Tanzania
1.1 Introduction
Lentil (Lens culinaris Medik.) is an important legume crop with respect to global production, trade, and consumption patterns. Lentil belongs to the Leguminosae family and is a self‐pollinated crop. It is one of the highly valued pulse crops in farming systems. Lentil is an annual legume plant with its lens‐shaped seed and is grown in more than 45 countries (Khazaei et al. 2019). An artificial intelligence (AI)‐based research data search engine (Dimensions 2022) indicates there are more than 147,000 publications, 75,000 patents, and over 150 clinical trials on lentils. These data clearly demonstrate the importance of lentils in today's world.
The total world production of lentils was 5.61 million metric tons (MT) in 2021, which has more than doubled from 2.66 million MT since 1991. Lentil production has shown a faster growth from 2011 to 2021 (an increase of 1.16 million MT) as compared to the preceding two decades combined total increase of 1.80 million MT. However, global lentil production experienced a significant drop in 2021 compared to 2020, when it had reached an all‐time high of 6.54 million metric tons. Traditionally, India had been the leading lentil producer in the world but Canada has emerged as a leader in recent years. During the last four decades, lentil has become a major pulse crop in the United States, mainly in the Pacific Northwest and Midwestern states (Siva et al. 2017). Canada has also become the leading lentil exporting country, while India ranks first in lentil imports. Although there have been wide variations in cultivated area of lentils in recent years, overall, it has also increased significantly from 3.27 to 5.59 million hectares for the 1991–2021 period. The yield of lentils was 1004 kg/ha in 2021, which also showed a significant increase from 813 kg/ha in 1991. The average yield has shown mixed trends over the last three decades, from a low of 780 kg/ha in 1992 to the highest figure of 1305 kg/ha in 2020 (FAO 2022).
Lentils have a long ancient and modern history of food use reported in the literature. Lentils originated in Turkey, with their consumption dating back to early civilization, as they have been an important food since prehistoric times and among one of the first food crops to have been cultivated (Sarker and Erskine 2006; Chelladurai and Erkinbaev 2020). It was produced in the Near East more than 8500 years ago (Asakereh et al. 2010). Lentils dating back to about 6800 BCE were found at an archeological site Yiftahel in lower Galilee area of Israel (Kislev 1985; Liber et al. 2021). Lentils were highly valued by the Egyptians. Later, during the Roman Empire, legumes were so highly valued that many affluent and prestigious Roman families adopted the name of the legumes as part of their names (Waines and Price 1975; Czapp 2007; Amin and Borchgrevink 2022; Guerra‐Garcia et al. 2022).
Due to its good protein content, carbohydrates, calories, essential minerals and vitamins, dietary fiber, soluble fiber, antioxidants, phytoestrogens, and folate compared to other legumes, lentils supplement cereal diets. It provides dietary amino acids and bioactive peptides that play major role in health. Its protein contents range from 21% to 36% (Oplinger et al. 1990; Jarpa‐Parra et al. 2014; Joshi et al. 2017; Jarpa‐Parra 2018; Dhull et al. 2022), with a balanced amino acid profile, significant content of low‐digestible carbohydrates, dietary fiber, and selected minerals and vitamins. Lentils have significant contents of resistant starch and a number of bioactive phytochemicals (Fouad and Rehab 2015; Morales et al. 2015a; Ma et al. 2018; Rezvankhah et al. 2021). Lentil crop promotes sustainable cereal‐based production systems with a potential of fixing free nitrogen (Matny 2015), which replaces inorganic fertilizers and thereby provides an attractive agricultural system and controls environmental pollution by reducing greenhouse gas emissions.
Traditionally, lentils have been considered as major source of protein and consumed regularly in many South Asian and Middle Eastern countries. Though the popularity of lentils has been growing rapidly in North America (United States and Canada), Australia, and many European countries. In South Asia (India, Pakistan, and Bangladesh), lentils are eaten with staple foods like chapati or flat bread and rice. Further, dehulled and split lentils or lentil flour are often used to make soups, stews, and fried products (Dagher 1991; Xu et al. 2019; Sidhu et al. 2022), and mixed with cereals to make bakery products and infant foods. Fried and roasted whole lentils are also processed and consumed, though on a smaller scale, in some countries. Lentils are also used as a source of starch for the textile industry.
Due to the inexpensive source of proteins, vitamins, and minerals, legumes including lentils are healthy choice for all consumers, and in particular for those who are vegetarians or vegans as well as those opting for environment friendly and sustainable meat alternatives of protein (Hill 2022; Oduro‐Yeboah et al. 2022). This chapter presents an overview of lentil production/trade, lentil types, value‐added processing, nutrients and antinutrients, and health benefits. The role of lentils in sustainable agriculture systems and world food security is also discussed.
1.2 Lentil Plant and Seed Characteristics
1.2.1 Plant Characteristics and Growth
The lentil plant is indeterminate, as it has considerable variation in its growth habit, which mainly depends on genotype (Saxena 2009). Plants are generally short (20–76 cm), with height depending on the climatic conditions and plant strains. It grows well in cool season, on leveled or partially rolling land having a pH of 6.0–8.0, under irrigated conditions (MFAL 2011). Saxena (2009) reported that under optimum environmental conditions, typically coinciding with late‐winter and early‐spring planting, lentil plants exhibit rapid vegetative/reproductive growth. Maturity is generally reached within 75–100 days after sowing date. Overall, height of stem and number and angle of branches, which determine the width of plant canopy, are the key traits contributing to plant structure.
Monteith (1981) noted that lentil plant growth is mainly affected by climatic conditions, especially variations in air and soil temperature, sunlight, moisture availability, and wind intensity. Intercropping is an option, as lentil is frequently grown alone. However, lentils can be intercropped with a variety of other crops, e.g., wheat, barley, rice, sugarcane, mustard, and linseed (McPhee et al. 2004). Lentil plant growth and crop yields are affected by abiotic stresses (drought, high temperature, rainfall, flooding) and biotic stresses (primarily diseases). Developing lentil genotypes resistant to these abiotic and biotic stresses is an important area of research in plant breeding and genetics. Kumar et al. (2021) reported that, in recent years, genomics‐assisted plant breeding practices have become a powerful tool to develop high‐yielding crops that adapt to abiotic stress, e.g., heat and drought stresses.
1.2.2 Seed Characteristics
Lentil seeds appear as oblong lens in shape and come in a variety of sizes. The seeds are produced within rhomboidal pods and have a diverse range of seed coat colors: red‐orange, purple, brown, green, or blackish‐brown, and spotted/dotted color patterns (Khazaei et al. 2019). Figure 1.1 shows images of major lentil types, whereas Table 1.1 lists selected physical characteristics of different lentil types.
1.3 Global Production and Trade
The total world production of lentils was 5.61 million metric tons (MT) in 2021, which represented an increase of about 111.1% as compared to 2.66 million MT in 1991 (Figure 1.2). During the period from 2011 to 2021, lentil production increased by 1.16 million MT or almost 26%, whereas in the preceding two decades (1991–2011), global production had increased by only 1.80 million MT. It is noteworthy that global lentil production peaked to 6.54 million MT in 2020 but declined significantly in 2021. The total area under lentil cultivation was 5.59 million hectares in 2021, which represented an increase of 71% compared to 3.27 million hectares in 1991. Further, during 2011–2021, area under lentils cultivation has ranged between 4.02 million hectares in 2014 and 6.10 million hectares in 2018, which represents wide variations in cultivated area of lentils in recent years.
Figure 1.1 Whole lentil seeds and split/dehulled dhal.
Source: Sidhu et al. (2022), with permission of John Wiley & Sons.
Table 1.1 Attributes of different lentil types.
Source: Adapted from Sidhu et al. (2022).
Lentil type
Color
Shape/surface
100‐seed weight (g)
Seed size, D × T
a
(mm)
Large lentil, whole
Greenish‐brown
Ovoid, convex, smooth
5.7
6.3 × 2.9
Large lentil,
dhal
b
Light‐red
Flat, smooth
2.5
6.2 × 1.4
Small lentil, whole
Brownish‐red
Ovoid, convex, smooth
3.6
4.9 × 2.8
Small lentil,
dhal
b
Red
Flat, smooth
1.5
4.7 × 1.3
a Diameter × thickness.
b Split, dehulled.
Figure 1.2 Word production and cultivated area of lentils (1991–2021).
Source: Adapted from FAO (2022).
The average yield of lentil was 1004 kg/ha in 2021, which exhibited a 23.5% increase compared to that in 1991, which was 813 kg/ha. During the 2011–2021 period, average yield ranged between 1038 kg/ha in 2018 and 1305 kg/ha in 2020. The year 2021 represented a sharp decrease of over 20% in average yield compared to the preceding year. It is noteworthy that year 2020 was the first time that average yield has exceeded 1300 kg/ha. Lentil yields, like any other field crop, are affected by climatic conditions or abiotic stresses (i.e., drought, high temperature, rainfall, and flooding) and biotic stresses (mainly diseases).
Figure 1.3 Percent share of lentil production by region in 2021.
Source: Adapted from FAO (2022).
Lentils are produced in over 45 countries; however, top 10 countries produce about 95% of total world production (FAO 2022). Significance of lentils, as a major legume crop, is demonstrated by the wide distribution of production in different agro‐ecological regions throughout the world (Figure 1.3). With respect to regional distribution, lentil production is led by Asia with 46.29% share of world production, followed by Americas (32.00%), Oceania (15.25%), Europe (3.27%), and Africa (3.20%). Lentil producing countries, further divided into subregions, are summarized below. Countries are listed in decreasing order of production by subregion and country‐wise within each subregion:
North America:
Canada, USA, Mexico
South Asia:
India, Bangladesh, Nepal, Pakistan
Oceania:
Australia, New Zealand
West Asia/Middle East:
Turkey, Syria, Iran, Yemen, Lebanon, Palestine, Jordan, Israel, Iraq
East Asia:
China, Myanmar
South America:
Argentina, Ecuador, Peru, Colombia, Chile
Central Asia:
Kazakhstan, Uzbekistan, Azerbaijan, Armenia
East Africa:
Eritrea, Ethiopia, Kenya
West Africa:
Algeria, Egypt, Libya, Madagascar, Malawi, Morocco, Tunisia
Europe:
Russian Federation, Ukraine, Belarus, North Macedonia, Bosnia, and Herzegovina
The top 10 lentil producing, exporting, and importing countries in 2021 and their percent global share in each category are listed in Table 1.2. Canada ranks first in global lentil production with 1,606,441 metric tons (MT), which accounted for 28.63% of world's total production. India (1,490,000 MT), Australia (853,642 MT), Turkey (263,000 MT), and Nepal (246,092 MT) were among the top 5 lentil producers, which represented 26.56%, 15.22%, 4.69%, and 4.39% share globally, respectively. It is noted that Canada had a significant decrease in lentil production from 2,867,800 MT in 2020, whereas India's production increased by about 26% from 1,180,00 MT in 2020. Overall, the top 10 lentil producing countries accounted for over 95% of the total global production of lentils in 2021 (FAO 2022).
Table 1.2 Top 10 lentil producing, exporting, and importing countries in 2021, by quantity (metric tons, MT) and respective global share (%) in each category.
Source: Adapted from FAO (2022).
Lentil producers
Lentil exporters
Lentil importers
Country
Quantity (MT)
Global share (%)
Country
Quantity (MT)
Global share (%)
Country
Quantity (MT)
Global share (%)
Canada
1,606,441
28.63
Canada
1,928,933
50.90
India
724,537
17.79
India
1,490,000
26.56
Australia
840,230
22.17
Turkey
536,702
13.18
Australia
853,642
15.22
Turkey
289,418
7.64
Bangladesh
455,298
11.18
Turkey
263,000
4.69
UAE
268,969
7.10
U.A.E.
244,420
6.00
Nepal
246,092
4.39
United States
201,674
5.32
Sri Lanka
205,281
5.04
Bangladesh
185,500
3.31
Russian Fed.
80,979
2.14
Pakistan
164,911
4.05
Russian Fed.
176,132
3.14
Kazakhstan
48,083
1.27
Egypt
145,852
3.58
China
165,158
2.94
Egypt
15,272
0.40
Ethiopia
103,000
2.53
United States
150,910
2.69
Belgium
12,219
0.32
Venezuela
100,000
2.46
Ethiopia
122,766
2.19
Syria
9936
0.26
Colombia
85,232
2.09
Traditionally, India had been the leading lentil producer in the world, but its lentil production has increased by only 1.4‐fold since the 2000. By contrast, some other countries, e.g., Australia and Canada have emerged as major producers of lentils since 2000, with 5.2‐fold and 1.8‐fold increases, respectively. Turkey has shown decreasing production trends, especially, since 2005, from 570,000 MT to 263,000 MT in 2021. The consumer demand for meat alternatives, i.e., non‐animal protein sources, as well as trends in greater diversity in exotic cuisines could be the most likely reasons for significant increases in lentil production in developed countries, e.g., Australia, Canada, and United States, which have also emerged as major exporters of lentils.
In 2021, the total global exports of lentil were 3,779,792 MT, equivalent to US $2.83 billion. Canada led global exports with 1,928,933 MT (Table 1.2) or 50.90% of global exports, followed by Australia (840,230 MT), Turkey (289,414 MT), UAE (268,969 MT), and United States (201,674 MT), which accounted for 22.17%, 7.64%, 7.10%, and 5.32% of global exports, respectively. Canada and the United States exported more lentils than it produced in 2021, due possibly to the export of previous year's stocks and including some imports. Nearly all of the global lentil exports (about 98%) were by the top 10 lentil exporting countries. It is noted that UAE does not produce lentils locally; therefore, the exports from UAE primarily constitute re‐packaged imported lentils. With respect to global imports of lentils, India led all countries with 724,537 MT or 17.79% of global imports, followed by Turkey (536,702 MT or 13.18%), Bangladesh (455,298 MT or 11.18%), UAE (244,420 MT or 6.00%), and Sri Lanka (205,281 MT or 5.04%). The top 10 lentil importing countries had about 68% of the global lentil imports.
1.4 Preharvest and Preharvest Quality Management
As is the case with other grain crops, the preharvest crop management has a substantial impact on the postharvest quality of lentils. Therefore, to ensure a good quality of harvested lentil crop, appropriate preharvest practices are followed in developed countries (e.g., Canada, Australia, and United States). Among these practices, the use of crop desiccants is commonly practiced, with an objective to ensure uniform maturity (or plant dry‐down) and maximize yields through improved harvest efficiency. Generally, preharvest herbicides are also applied when the crop is mature (i.e., when the seed color changes). The herbicide use is highly regulated since each herbicide has specific restrictions with respect to the end‐use of the crop after the harvest (Bruce 2008; Bertholet 2019). Lentil crop production practices in the least developed countries rarely employ the use of preharvest desiccants and herbicides, which negatively impacts the lentil crop yields and its postharvest quality.
Typically, harvesting of lentils at a moisture content of 18–20% is recommended, which is higher than the optimum postharvest storage moisture content of 13–14% but is necessary for avoiding shattered seeds of <18% moisture. Upon delivery to the elevator (storage facility), lentils are cleaned and sorted to remove field debris and damaged seeds. Prior to postharvest storage, lentils are dried to 13–14% moisture content to optimize yield of high quality, i.e., seed color uniformity and for safe long‐term storage without subsequent seed breakage or damage. The removal of field stones, split/damaged lentils, and light and heavy debris can be achieved by de‐stoners, air aspirators, and gravity separators. Moreover, mesh screens of different sizes are used to remove extraneous organic/inorganic materials, such as immature seeds, stalks, stones, and other field debris. At 14% moisture and 15 °C (recommended conditions), lentils could be stored safely for up to 40 weeks, without any damage to the seed coat and overall quality (Tang et al. 1991; Joshi et al. 2017; Oduro‐Yeboah et al. 2022). Grading of lentils for quality standards is commonly done before bulk and retail sales (lentil grades are well established in Canada, Australia, and United States).
A careful monitoring of storage temperature and relative humidity (RH) is important during postharvest storage of lentils for optimum quality preservation since any fluctuations in the storage conditions impact the quality negatively. In the humid climates, high RH is common for most of the year, which can increase the moisture content of grains (like lentils) stored in porous woven bags (i.e., gunny/jute bags). Such conditions allow fungal and insect infestations. Therefore, the use of polypropylene bags with adequate moisture barrier is recommended for lentils packaging and shipping. Oduro‐Yeboah et al. (2022) reported that in the developing countries, a lack of appropriate storage facilities is the major cause of postharvest losses in lentils in terms of both quantity and quality. Furthermore, poor packaging, transportation, and handling are other significant factors contributing to postharvest losses in developing countries.
1.5 Nutritional Profile and Health Benefits
Lentils have a nutrient‐dense profile and offer a good balance between protein and carbohydrates. For example, when compared to three major staple foods (Table 1.3), wheat, corn, and rice, lentils have 1.8‐fold, 2.6‐fold, and 3.5‐fold more protein content, respectively (USDA 2022). On the other hand, carbohydrate content in these three cereal crops is 12–26% higher than that in lentils. Further, ash content is also significantly higher than that in wheat, corn, and rice, which is comprised of the reported minerals: calcium, potassium, phosphorus, iron, manganese, copper, molybdenum, boron, iodine, cobalt, zinc (Mamakhai and Zagoruiko 2022). Lentils also contain fatty acids from the omega‐3 and omega‐6 groups. This important balance between relatively high‐quality protein and mineral content and lower carbohydrate content is an important feature of lentils from a human health perspective (Dhull et al. 2022).
Table 1.3 Composition of lentil compared to major cereals.
Source: Adapted from USDA (2022).
Composition
Lentil
Wheat
Corn
Rice
Protein
24.6
13.7
9.4
7.1
Carbohydrate
63.4
71.1
74.3
80
Total lipids
1.1
2.5
4.7
0.7
Ash
2.7
1.8
1.2
0.6
1.5.1 Nutritional Profile
The composition of raw and cooked lentils is shown in Table 1.4. Based on per cup basis, lentil's protein content is 45.90, 17.90, 9.65, and 8.81 g in raw, cooked/boiled, soup, and curry, respectively (USDA 2022). During hydration and cooking, lentils absorb >100% water, which lowers nutrient content on prepared or ready‐to‐eat weight basis. Nonetheless, lentils still offer a balanced and healthy nutritional profile on per serving basis. It is noted that a considerable variation in nutrient composition of lentil seeds is reported in the literature due mainly to varietal differences (Thavarajah et al. 2008; Joshi et al. 2017).
Table 1.4 Composition of raw and cooked lentils (per cup).
Source: Adapted from USDA (2022).
Composition
Unit
Raw, red or pink (192 g)
Cooked/boiled, no salt (198 g)
Soup (248 g)
Curry (240 g)
Proximate
Water
g
15
138
210
184
Energy
kcal/kJ
687/2880
230/964
159/667
264/1107
Protein
g
45.90
17.90
9.65
8.81
Ash
g
5.76
1.64
—
—
Total lipid (fat)
g
4.17
0.75
4.24
13.5
Carbohydrate, by difference
g
121
39.8
21.9
29.5
Dietary fiber
g
20.7
15.6
7.94
8.16
Minerals
Calcium
mg
92.2
37.6
29.8
60
Iron
mg
14.2
6.59
2.9
3.46
Magnesium
mg
113
71.3
32.2
55.2
Phosphorus
mg
564
356
166
187
Potassium
mg
1280
731
342
701
Sodium
mg
13.4
3.96
464
919
Zinc
mg
6.91
2.52
1.24
1.42
Selenium
μg
0
5.54
3.22
3.6
Vitamins
a
Vitamin C
mg
3.26
2.97
3.22
17.8
Niacin
mg
2.88
2.1
1.06
1.9
a Other vitamins <1.0 mg content.
The amino acid profile of lentil seeds is among the richest in cool season pulses, as all lentil types provide sufficient amounts of the most essential amino acids to meet the nutrient requirements. However, similar to most other pulses, lentils are deficient in sulfur‐containing amino acid, methionine (Iqbal et al. 2006; Yadav et al. 2007). When lentils are consumed with cereal‐based foods, which have methionine (e.g., flat wheat bread, rice), lentils provide complete proteins with adequate amounts of all the essential amino acids (Sidhu et al. 2022). It is important to fully understand the quantity/quality of proteins in the legume ingredients that are used in the formulations of various foods. Complementary blending of proteins will reduce the limiting amino acids; however, it is essential for specific complimentary protein formulations to be fully assessed prior to adoption for use in commercially prepared foods directed for use in supplemental feeding programs.
Lentils are a rich source of resistant starch, which varies between 11.4% and 14.9% for different cultivars (Perera et al. 2010). From a rate of digestion perspective, starches are classified into different groups, namely rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). The RDS, commonly referred to as “bad” starch, is readily digested in the small intestine, therefore eliciting a high glycemic response. On the other hand, the SDS is digested at a slower rate, which results in a relatively lower glycemic response in blood. By contrast, the RS is not digested in the small intestine but it undergoes fermentation by the microorganisms in the large intestine (Englyst et al. 1992). Ahmed and Auras (2011) suggested that, besides traditional uses, lentil starch has potential in the formulation of manufactured foods for diabetics.
Lentils are rich in phenolic contents, which demonstrates its relatively higher antioxidant activity. Lentils also possess numerous biologically active phytochemicals, i.e., flavonoids, phytic acid, saponins, and tannins (Oomah et al. 2011; Zou et al. 2011; Bautista‐Expósito et al. 2018; Yeo and Shahidi 2020; Paranavitana et al. 2021). Some of these compounds (e.g., tannins) are considered as antinutrients due to their interference with minerals' absorption, especially iron. Aguilera et al. (2010) studied the effects of soaking, cooking, and dehydration on the phenolic profile and the antioxidant properties in Pardina lentil. Higher antioxidant activity was observed in raw or control lentils than that in processed samples. The industrial processing (hydration) reduced catechins and procyanidins, flavonoids, and flavanone, while hydroxybenzoic compounds were shown to increase significantly.
1.5.2 Antinutritional Factors
Lentils, like other legumes, contain a variety of bioactive compounds that have been traditionally referred to as antinutrients or antinutritional factors due to a negative impact on nutritional quality, specifically digestibility, bioavailability, and bioaccessibility if pulses are not fully cooked (Nosworthy et al. 2018). These compounds include trypsin inhibitors (TIs), chymotrypsin inhibitors, α‐amylase inhibitor, phenolics/tannins, saponins, phytohemagglutinins (lectins), phytic acid/phytate, flavonoids, goitrogens, and oxalic acid (Ruiz et al. 1996; Shnyrov et al. 1996; Ragg et al. 2006; Thavarajah et al. 2010; Mirali et al. 2016; Ganesan and Xu 2017). In the past, some of these compounds were considered to impart only negative health effects but they are now being re‐evaluated and recognized as having important health benefits, e.g., antioxidant and anti‐inflammatory activities (Campos‐Vega et al. 2010; Ganesan and Xu 2017; Wiesinger et al. 2022). It has also been reported that improved processing through application of heat and incorporating organic acids, e.g., ascorbic acid, significantly reduces antinutritional factors. Even pre‐soaking legumes in hot water prior to processing can lower the antinutrient concentration, e.g., lectin, and flatulence causing oligosaccharides, i.e., raffinose and stachyose (Khattab and Arntfield 2009; Alphonce et al. 2020).
1.5.3 Health Benefits
Regular consumption of lentils, similar to other pulses, offers a variety of health benefits. Benefits of consuming lentils have been reported in many other biological processes, i.e., lowering blood cholesterol levels and acting as an antioxidant (Khandelwal et al. 2010; Patterson et al. 2017; Kamboj and Nanda 2018; Johnson et al. 2020; Didinger and Thompson 2022). Lentil consumption is also effective against various chronic disease conditions such as cardiovascular diseases, hypertension, hypercholesterolemia, and cancer (Alshikh et al. 2015; Moreno‐Valdespino et al. 2020: Verni et al. 2020). Higher protein content and significant dietary fiber content in lentils lead to a slower digestion of available carbohydrates and hence a lower glycemic response. One cup of cooked lentils contains about 15.6 g of fiber, which fulfills about 60% daily fiber requirement. Dietary fiber has been shown to impart beneficial effects, e.g., regulating bowel function and probiotics' growth stimulation (Johnson et al. 2020; Sidhu et al. 2022).
Besides modern research, health benefits of consuming lentils are mentioned in ancient treatment remedies as well (Lardos 2006; Faris and Attlee 2017). Lentil soup was consumed as a staple meal in the ancient world, as it was also prepared for ailing individuals as a health remedy (Totelin 2015). Lentil seeds have been reported to be used in the folk medicine to treat different illnesses, e.g., against diabetes, for treating skin infections using lentil‐water paste topically (Houshmand et al. 2016), and for treating burns by direct application of roasted and milled lentil flour (Sezik et al. 2001; Giday et al. 2007).
1.6 Lentil Processing and Emerging Trends
1.6.1 Value‐Added Processing
Value‐added processing of lentils involves diverse processing methods, which produce a variety of end products. The processing of lentils can be divided into three levels: (i) Primary processing, e.g., cleaning, sorting, grading, and packaging to market whole lentils for domestic cooking and commercial processing; (ii) secondary processing, e.g., dehulling, splitting, and polishing of the whole/split lentils; and (iii) tertiary processing that involves grinding/milling of whole or dehulled seeds and separating protein‐ and starch‐rich fractions for use in a variety of food products. Further, a very limited supply of thermally processed (canned) lentils are available in commercial retail food distribution (Joshi et al. 2017; Oduro‐Yeboah et al. 2022). Boye et al. (2010b) reported that besides balanced nutrition, lentil and other legume proteins also possess a variety of functional properties, which are known to play an important role in food formulations, processing, and new product development. Some examples of these functional properties include solubility, water and fat binding capacity, gelation, and foaming, all of which play an important role in the development of diverse food products (e.g., bakery products, soups, pastas, and extruded products).
Dehulling of lentils is a commonly used method to process split lentils or dhal. It is common to soak and temper pulses with water to facilitate hulling process. Milling, either dry or wet, is used to produce legume flour and protein‐ or starch‐rich fractions and isolates (Ahmed et al. 2016; Ma et al. 2016; Aryee and Boye 2017). It is to be noted that the type of milling method used has significant effect on the functional and sensory properties of flours and fractions. The functional properties of flours and fractions must be assessed fully before their application in diverse foods. Additionally, extrusion processing can be used to prepare lentil flour by optimizing feed‐rate, moisture content, and process temperature parameters (Dhull et al. 2022).
Various cooking or processing methods, besides improving palatability and nutrient availability, also affect the protein digestibility and level of antinutritional factors in lentils. Soaking in water is shown to effect significant reduction in the phytic acid content, while the addition of sodium bicarbonate (NaHCO3) in soak water results in the reduction of phenolics and tannins (Aguilera et al. 2009; Ma et al. 2011; Martín‐Cabrejas et al. 2009; Morales et al. 2015b; Joehnke et al. 2021; Dhull et al. 2020, 2022). Different processing methods have variable effect on nutritional profile of lentils and reduce antinutrients as well. Autoclaving improves digestibility, starch gelatinization, and physical disintegration of lentil seed (Hernández‐Nava et al. 2011; Świeca 2015; Dhull et al. 2022). Extrusion cooking is also reported to be efficient in improving nutritional quality and increases shelf life of lentils with enhanced flavor and textural attributes (Rathod and Annapure 2017). Germination/sprouting of lentils has significant positive effect on compositional/nutritional quality, e.g., increased crude protein and reduced lipids, carbohydrates, phytic acid, and tannins (Ghumman et al. 2016).
Sozer et al. (2017) reported that the use of pulses is projected to expand as plant‐based protein alternatives for meat and as environmentally sustainable food options. Moreover, pulses or pulse ingredients, combined with cereal grain ingredients, would find potential new applications to offer nutritious and healthy food choices for worldwide consumers. Siddiq et al. (2022) indicated that the popularity of convenience foods, e.g., dehydrated, extruded, frozen, and microwavable food products, has provided multiple venues for the development of new lentil‐based, gluten‐free products.
1.6.2 Emerging Research and Development Trends
Lentil is a least researched legume crop; therefore, the emphasis should be on lentil value chain (LVC), especially in breeding strategies to develop varieties with high yield (Kaale et al. 2022). A number of innovative technologies have been introduced for processing and preservation of food products, which could be applied for grain legume processing. As previously discussed, legumes, including lentils, possess some antinutrient factors, e.g., TIs; new processing techniques have been researched to eliminate or significantly reduce TIs in protein concentrates or protein isolates. Boye et al. (2010a) investigated ultrafiltration and isoelectric‐precipitation application and evaluated the effect on the functional properties of protein concentrates from lentil and two other pulses. The ultrafiltration treatment yielded significantly higher protein content in the concentrates (from 69.1% to 88.6%), than with the isoelectric‐precipitation method that yielded 63.9–81.7% protein. Furthermore, concentrate of red and green lentils showed higher protein solubility of 70–77% using ultrafiltration isolation.
Ahmed et al. (2019) investigated the effect of high pressure (HP, 300, 450, and 600 MPa) for 15 minutes on the alcalase‐induced enzymatic hydrolysis (AEH) of lentil protein (LP). The HP application prior to AEH resulted in significant changes to the secondary structure of proteins. The foaming properties and antioxidant activities were improved by 50% and 100%, respectively. In another study, Ahmed et al. (2016) noted that the HP treatment of lentil starch can be potentially utilized to formulate new products with optimally desired functional and sensory properties. Primozic et al. (2018
