Date of Graduation

12-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Matlock, Marty D.

Committee Member

Thoma, Gregory J.

Second Committee Member

Liang, Yi

Third Committee Member

Miller, Perry

Keywords

beans peas lentils; food systems; Life cycle assessment; pulse crops; sustainable agriculture

Abstract

Environmental sustainability and human health impact of pulses produced and consumed in the United States was assessed using life cycle assessment (LCA). The study included three objectives 1) to estimate environmental impact of current production and consumption practices in the United States using attributional LCA; 2) to estimate environmental and human health impact of iso-caloric diets containing varying amounts of pulses using Hybrid-LCA and Combined Nutritional and Environmental-LCA (CONE-LCA); and 3) to estimate environmental impact of increased demand for pulses using consequential LCA. Scope of the study varied for each objective with system boundary encompassing cradle-to-grave activities for objective 1 and 2 and cradle-to-processor gate activities for objective 3. In objective 1 cradle-to-grave environmental impacts of current production practices in the US were estimated for dry bean, chickpea, field pea, and lentil for the functional unit (FU) of 60 g of pulses (approx. ¼ cup) consumed per week. In addition, impact of four cooking methods, open-vessel cooking (OVC), cooking in stovetop pressure cooker (SPC), cooking in electric pressure cooker (EPC), and cooking in larger quantity (e.g., 1 kg instead of 60 g) in open vessel (OVC-RF1), was evaluated. Statistically significant decrease in environmental impact (all impact categories except LU and WC) for all species of pulses was achieved with EPC and OVC-RF1 compared to OVC. Energy used for cooking at the consumer stage, and resource use (fertilizers, fossil fuels etc.) were identified as the hotspots in the study. Comparison of current (CDP) and recommended (RDP) iso-caloric diets containing varying quantities of pulses was conducted in Objective 2 for FU of 1800 kcal to females and 2400 kcal to males. RDPs included healthy-styled US diet (HealthyUS), ovo-lacto-vegetarian diets according to 2015 (Veg2015) and 2010 (Veg2010) USDA recommendations, and vegan diet (Vegan2010) according to 2010 USDA recommendations. Compared to CDP, statistically significant increase in GWP was observed for HealthyUS for sex-specific diets, while Vegan2010 lowered (statistically significant) GWP for both sexes. Statistically significant health benefits were offered only by Vegan 2010, Veg2010, and Veg2015. Pulses provided 29% to 42% of protein in vegetarian and vegan diets while contributing only between 0.06% and 0.84% of GWP for these diets. Moreover, when compared to other sources of protein pulses had the lowest GWP and greatest nutritional density. Pulses also offered potential environmental gains compared to beef even when production and processing of pulses was increased to meet potential increase in demand. The FU for Objective 3 was an amino acid profile comparable to beef. Beef was considered as the protein source substituted by pulses because of its high environmental and adverse health impact. To meet the requirements of the FU consumption of pulses was complemented with rice at a ratio of 1.35:1 (pulses+rice). While this additional production and processing of pulses and rice would increase the environmental impact, potential environmental gains could be achieved if increased demand for protein were to be fulfilled by pulses and rice instead of beef (i.e., 57 – 92%). The study concluded that pulses can be environmentally sustainable source of protein especially if they are cooked in electric pressure cooker and/or in batches larger than 60 g. Considering their higher nutritional density score and lower environmental impact compared to other sources of protein, their increased inclusion in diet could offer health benefits by lowering disability adjusted life years (DALYs) associated with CDP. While this increased inclusion of pulses may require increasing their production and processing, net environmental benefits can still be achieved compared to complete reliance on animal sourced protein such as beef. However, complete substitution of animal-sourced protein with only pulses is not recommended because such change may cause unintended consequences in terms of meeting nutritional requirements. Care must be taken to ensure that all nutritional requirements are fulfilled while decreasing environmental impacts.

Download

Share

COinS