factors influence the quality of the final dry bean product. These include cultivar, seed source, agronomic conditions, handling and storage of the dry product, and processing procedures during cooking or canning. Quality changes in dry beans during cooking and processing are associated with their inherent physical components and chemical constituents (Hosfield and Uebersax 1980; Uebersax 1991). It must be noted that cooking and processing techniques improve the palatability, digestibility, and bioavailability through cellular separation and inactivation of antinutrional components.
Table 1.7. Typical constraints associated with legumes utilization, their negative effects and possible solutions.
Source: Maphosa and Jideani (2017).
| Constraint | Negative effect | Solution |
|---|---|---|
| Trypsin and amylase inhibitors | Decrease protein and starch digestibility | Boiling dry beans generally reduces the content by 80–90% |
| Phytate | Chelates with minerals resulting in poor mineral bioavailability | Dehulling, soaking, boiling, steaming, sprouting, roasting and fermentation, autoclaving, gamma irradiation |
| Lectins, saponins | Reduced bioavailability of nutrients | Most destroyed by cooking, soaking, boiling, sprouting, fermenting |
| Oligosaccharides | Flatulence and bloating | Soaking, cooking, germination, and changing boiling water |
| Hard‐to‐cook phenomenon | Energy and time consumption | Soaking legumes before cooking |
| Low levels of sulfur‐containing amino acids | Incomplete protein source | Consuming in combination with cereals (high in sulfur‐containing amino acids) |
| Low iron bioavailability | Poor source of iron | Consuming in combination with vitamin C rich foods to increase iron absorption |
| Lack of convenient food applications | Boredom of eating the same food repeatedly | New and convenient product development using whole legumes or legume ingredients |
| Lack of awareness and understanding of nutritional benefits of legumes | Low intake of legumes | Increasing consumer awareness of the nutritional and health benefits of legumes |
| Reluctance to try a new food or to change eating habits | Low intake of legumes | Development of innovative, attractive legume‐based products to entice consumers |
A comprehensive assessment of strategies and procedures used for processing dry beans is prerequisite to improved utilization of dry beans. Implementation of a given protocol can be maximized through an understanding of the physical and chemical components, the inherent constraints and diversified processing techniques available to develop economically viable alternative and innovative products (Uebersax et al. 1991). Improved utilization of dry beans can be maximized through an understanding of how physical and chemical components function and react under given process conditions. Further, variability in the physico‐chemical composition of dry beans occurs, warranting research and quality control programs directed to provide a consistent product possessing characteristics of acceptable flavor, bright color, attractive appearance, uniform texture, and high nutritional quality.
LEGUMES AND SUSTAINABILITY OF AGRICULTURAL SYSTEMS
Pulses provide environmentally sustainable source of nutrients‐rich food for humans and animals, as summarized in Figure 1.7 (GAP.org 2016). Sustainability of agricultural systems embrace long‐term environmental consequences that transcend short‐term productivity and efficiency objectives. A truly broad‐based construct associated of sustainability promotes the integration of food production practices and social needs. Thus, globally, agriculture sustainability must be considered as a social process besides technological practices and innovations. The production of legumes (dry beans and other pulses) has a rich and diverse history and serves as a global food resource within both industrially developed nations and indigenous populations. Since producing plant‐based foods are by far more environmentally conservative than the animal‐based ones (Gogoi et al. 2018), legumes will continue to play an increasingly major role to meet human food needs. Several elements of agricultural sustainability are clear or inherent in the production of pulses due to the considerably high total calorie and protein contents derived per unit of energy input:
Fig. 1.7. Pulses as environmentally sustainable food source for healthy people and healthy animals.
Source: Adapted from GAP.org (2016).
Nitrogen fixing. Legume crops are distinguished by their unique ability to “fix nitrogen” and thus have significant impact on their need for soil‐borne nitrogen (Liu et al. 2011). By contrast, typically, major crops such as corn, wheat, and rice require added nitrogen to be productive and yield sufficiently to be economically viable. A progressive crop rotation is essential to maintain vital soil health and for managing weeds and disease pressure. Growers are generally diversified among several crops (e.g., corn, wheat, soybeans) – they are not exclusively dry bean producers on their farm acreage. Therefore, most fields are used for dry beans or other pulses every 3–5 years depending on the prescribed rotation. Not only do pulses directly benefit from the root‐nodulation encapsulated symbiotic bacteria, rhizobia, that generate soil nitrogen, but there is significant carryover nitrogen levels that benefit the subsequent rotation crop.
Drought tolerance. Dry beans and other pulses are much more drought tolerant (GAP.org 2021) than many other major crops, particularly cereal crops. Dry beans require less total water and significantly less irrigation than alternative crops since arid and semi‐arid lands require the use of supplemental water to sustain plant growth (Ye et al. 2018). Dry beans require differential levels of water during various stages of growth, which is precisely determined and controlled. Moreover, dry beans and other pulses will reproduce seed under the most drought stressed conditions where the cereal grains will fail to reproduce.
Field drying. Legumes are efficient at harvest because they require no or very limited external/additional seed drying as is common with corn, wheat, rice, and other cereal grains. Beans and other pulses are naturally dried to a moisture content of around 18% prior to harvest. By contrast, typically, corn and cereal grains require artificial, forced air drying, which requires huge fossil fuel (propane) energy input to reduce moisture content suitable for stable storage without mold/bacterial development and spoilage.
Harvesting efficiency. Dry beans are increasingly produced from plants possessing an upright architecture that allows for more rapid drying and direct cutting with mechanized combines rather than traditional pulling of the plants and windrowing for air drying. This energy‐efficient innovation reduces overall fuel consumption compared to traditional harvest systems and avoids multiple field passes, which