Effect of roasting pulse seeds at different tempering moisture on the flour functional properties and nutritional quality

Nutritional, functional, and microbial qualities of legume-based flour blends processed by SMEs in Zambia and Malawi compared to standard Corn-Soy Blend Plus (CSB +): a cross-sectional study

BACKGROUND

Legumes enhance food security in developing countries, necessitating an understanding of their properties. This study examined the nutritional, functional, and microbial qualities of legume-based flour blends from Small and Medium Enterprises (SMEs) in Malawi and Zambia. SMEs were chosen for their key role in local food production, distribution, and complementary food supply.

METHOD

A total of 36 legume-based flour blend samples were collected using snowball sampling, consisting of 21 samples (7 sets of 3 similar samples) from SMEs in Zambia and 15 samples (5 sets of 3 similar samples) from SMEs in Malawi. Samples were analyzed for proximate composition, energy, iron, and zinc content. The nutritional contributions to the Recommended Dietary Allowances (RDA) for children aged 1-3 years were assessed. Additionally, functional properties such as water-holding and oil-holding capacities were measured. Microbial analysis was performed, and the data were statistically analyzed to determine significance (p ≤ 0.05).

RESULTS

Our findings revealed substantial variability in the nutritional content of these flour blends. Protein content ranged from 9.4% to 41.5%, carbohydrates from 8.1% to 71.3%, crude fat from 2.3% to 26.8%, and crude fiber from 6.2% to 35.2%. Iron and zinc levels also varied significantly, from 2.9 to 21.9 mg/100 g and 2.2 to 5.2 mg/100 g, respectively. These inconsistencies highlight a lack of standardization in nutrient content for blends intended for infant feeding. When prepared as 96 g porridge servings for children aged 1-3 years, the blends provided notable contributions to the Recommended Dietary Allowance (RDA). However, their nutrient levels were generally lower compared to the standard Corn-Soy Blend Plus (CSB +). The flour blends also showed variations in physico-functional properties, and some had microbial loads exceeding 250 cfu/g, reflecting inadequate hygiene practices during processing.

CONCLUSION

To enhance their products, SMEs should ensure that their flour blends meet both nutritional and safety standards while striving to match or surpass the nutrient content of CSB + to remain competitive in the market.

Flours from fermented lentil and quinoa grains as ingredients with new techno-functional properties

The need to provide novel, nutritious plant-based products requires seeking high-value, sustainable protein sources, like quinoa and lentils, having an increased digestibility and lacking antinutrients. Fungal fermentation has evidenced enhanced nutritional value of flours obtained from these grains. However, research into techno-functional properties, essential to the new product development, is lacking. This study investigated the techno-functional properties of flours made from lentil and quinoa after fermenting them with Pleurotus ostreatus and subjecting them to two drying techniques (lyophilisation and hot air drying). In both cases, the fermentation led to noteworthy improvements in swelling and water holding capacity, especially in those lyophilised than those dried. In contrast, the emulsifying, foaming, thickening, and gelling capacities decreased significantly. The loss of abilities was more severe for dried grains than for lyophilized ones. The thermomechanical analysis of the fermented flours showed lower thickening and gelling potential compared to untreated flours. Microscopy images revealed that the state and structure of starch granules were affected by both fermentation and drying processes. Starch granules in lentils were partly pre-gelatinised and trapped in the cotyledon cell, resulting in limited thickening and gelling abilities. In contrast, in quinoa, starch underwent pre-gelatinisation and retrogradation during the fermentation process, promoting the production of resistant starch and increasing fibre content. This study presents the potential of treated flours as ingredients possessing unique attributes compared to protein and fibre-rich conventional products.

Impact of cooking on the protein quality of Russet potatoes

Despite being low in crude protein, on a fresh weight basis, given their overall contribution to the North American diet, potatoes contribute approximately 2%-4% of the population's protein intake. However, the quality of the protein remains ill-defined. To that end, Russet potatoes were secured and subjected to various cooking conditions (raw [control], boiled, baked, microwaved, and fried [3, 6, and 9 min]) to determine the impact of cooking method on protein quality, as determined by amino acid score (AAS) and indices of in vivo true fecal protein digestibility (TFPD%; rodent bioassay) and in vitro protein digestibility (pH-drop, pH-Stat, and simulated gastrointestinal digestion both static and dynamic). The AAS of raw Russet potatoes was 0.67 ± 0.01, with histidine being the limiting AA. Frying led to a significant reduction in the AAS, however, other cooking methods yielded similar results to the raw control. The TFPD% of raw potato was low (40.5% ± 3.9%) and was significantly enhanced to over 80% with all cooking methods. Similar patterns were observed with all in vitro measures, however, all methods yielded higher values for the raw control samples. Final protein digestibility-corrected AAS (PDCAAS; product of AAS and TFPD%) values ranged from 0.27 (raw) to a high of 0.57 (boiled), with cooked values being comparable to other plant-based protein sources, including grains, and some nuts and pulses. In vitro PDCAAS values followed similar trends. This study defined the protein quality of cooked Russet potatoes and provides data for use in defining the quality of total protein consumed in the North American diet.

Quantifying the effects of pre-roasting on structural and functional properties of yellow pea proteins

Roasting could modify the protein structure/conformation, contributing to changes in functional properties. Here we investigated the effects of pre-roasting on the extraction efficiency, structural and functional properties of pea protein concentrates and isolates (PPC and PPI) produced from yellow split peas. The shorter roasting times (150 °C, 10 and 20 min) had little effect on protein yields and could increase the solubility of PPC or PPI by ∼ 12% at pH 7 and enhance the solubility of PPI by ∼ 12% (10-min roasting) and ∼ 24% (20-min roasting) at pH 3. However, a longer duration of pre-roasting (150 °C, 30 min) significantly reduced the extraction efficiency of PPC and PPI by ∼ 30% and ∼ 61%, respectively. Meanwhile, pre-roasting had minor effects on SDS-PAGE profiles and the secondary structures of pea proteins but significantly altered tertiary structures by reducing free sulfhydryl groups, increasing disulfide bonds and surface hydrophobicity. As for the emulsifying properties, pre-roasting improved the emulsion ability index (EAI) of PPC and PPI but decreased the emulsion stability index (ESI) of PPC and had no significant effect on PPI. Moreover, PPC and PPI with shorter pre-roasting duration (10 and 20 min) had endothermic peaks and showed a slight decrease in the denaturation temperature (Td) and the onset temperature (To), respectively. Overall, the study demonstrated that controlled pre-roasting at 150 °C for 10 min and 20 min altered protein structures (mainly tertiary structures), improving the solubility and EAI of pea proteins at pH 7, while retaining their thermal properties in comparison to unroasted samples.

A comprehensive review on pulse protein fractionation and extraction: processes, functionality, and food applications

The increasing world population requires the production of nutrient-rich foods. Protein is an essential macronutrient for healthy individuals. Interest in using plant proteins in foods has increased in recent years due to their sustainability and nutritional benefits. Dry and wet protein fractionation methods have been developed to increase protein yield, purity, and functional and nutritional qualities. This review explores the recent developments in pretreatments and fractionation processes used for producing pulse protein concentrates and isolates. Functionality differences between pulse proteins obtained from different fractionation methods and the use of fractionated pulse proteins in different food applications are also critically reviewed. Pretreatment methods improve the de-hulling efficiency of seeds prior to fractionation. Research on wet fractionation methods focuses on improving sustainability and functionality of proteins while studies on dry methods focus on increasing protein yield and purity. Hybrid methods produced fractionated proteins with higher yield and purity while also improving protein functionality and process sustainability. Dry and hybrid fractionated proteins have comparable or superior functionalities relative to wet fractionated proteins. Pulse protein ingredients are successfully incorporated into various food formulations with notable changes in their sensory properties. Future studies could focus on optimizing the fractionation process, improving protein concentrate palatability, and optimizing formulations using pulse proteins.

Modification of physicochemical, functional properties, and digestibility of macronutrients in common bean (Phaseolus vulgaris L.) flours by different thermally treated whole seeds

The utilization of beans (Phaseolus vulgaris L.) is hindered by unpleasant flavors, low macronutrients digestibility, and long cooking time. The pre-thermally treated beans can overcome these limitations. Therefore, the effect of thermal methods (moist-heat and dry-heat) and bean market classes (black, navy, kidney, and pinto) on functional properties and digestibility of bean flours were compared to raw counterparts. Within bean class, moist-heated samples showed increased water-holding capacities of 2.54-2.87 g H₂O/g sample and starch/protein digestibility whereas dry-heated samples showed enhanced flavor profile and increased oil-holding capacities of 1.04-1.14 g oil/g sample. Among bean classes, moist-heated kidney bean flour showed the highest water-holding capacity of 2.87 g H₂O/g sample and starch/protein digestibility while dry-heated pinto bean flour had the highest oil-holding capacity of 1.14 g oil/g sample. The current result may provide a basis for the development of pre-thermally treated legume flours and facilitate their applications.

Functional Properties of Physically Pretreated Kidney Bean and Mung Bean Flours and Their Performance in Microencapsulation of a Carotenoid-Rich Oil

Microencapsulation can improve protection for compounds that degrade easily, such as β-carotene that is present in large amounts in buriti oil (Mauritia flexuosa). Encapsulating matrices are mainly composed of proteins and polysaccharides, which are often combined to improve their performance as a protective barrier. Beans, such as dark red kidney beans (Phaseolus vulgaris) and mung beans (Vigna radiata), are excellent protein sources that contain significant amounts of the essential amino acids. Bean flours are low in fat and naturally provide a blend of high-quality protein and carbohydrates that may stabilize lipophilic compounds for subsequent spray-drying. Whole bean flours, rather than refined individual biopolymers, may represent more sustainable alternative wall materials for microencapsulate bioactive compounds. This work aimed to evaluate the use of flours produced from red kidney beans and mung beans, which have been submitted to different physical pretreatments, as wall materials for microencapsulation of buriti oil by spray-drying. Different bean treatments were evaluated: untreated (control), soaked in water for 24 h, and soaked in water for 24 h followed by boiling for 30 min. The flours' proximate composition was not affected by the treatments (p < 0.05), showing similar values of carbohydrate (63.8–67.9%), protein (19.2–24.6%), and lipid (1.2–1.9%) contents. Both bean species had the water absorption capacity (WAC) increased by boiling, while the oil absorption capacity (OAC) was not altered by the treatments. Flours produced with raw or soaked beans showed emulsion activity (EA) and emulsion stability (ES) greater than 70%. Raw bean flours also showed better foaming properties, which may be indicative of higher levels of antinutritional factors. The soaked bean flours showed the best results for both type of beans, especially with regard to emulsifying properties, and were selected as wall materials for buriti oil microencapsulation. Different ratios of flour and maltodextrin were used to produce oil-in-water emulsions that were then spray-dried. Buriti oil microcapsules showed good physicochemical properties, with moisture around 3%, aw <0.3, and hygroscopicity around 5%. The carotenoid encapsulation efficiency ranged from 68.2 to 77.9%. Bean flours showed to function as a sustainable and nutrient-rich alternative wall material for microencapsulation.