Physicochemical Properties and Cooking Quality of Selected Improved Bean Varieties Grown in Kenya

Abstract

Common beans (Phaseolus vulgaris L.) are a crucial food legume in Kenya, playing a significant role in meeting nutritional needs. Recognizing their importance, the Kenyan government has prioritized common beans under the agricultural transformation pillar of the Bottom-up Economic Transformation Agenda (BETA) 2023–2027 to enhance food and nutrition security. Additionally, common beans are considered a cost-effective dietary intervention aligned with the preventative health approaches of Universal Health Coverage (UHC). The objectives of this study were to determine the physico-chemical attributes, cooking quality, anti-nutrients (antinutrients and flatulence-causing oligosaccharides) factors and mineral bio accessibility of two improved bean varieties (Faida and RM 01) grown in Kenya. All the analysis were determined following standard procedures. There was no significant difference (P > 0.05) in width, bulk density, and true density of the two varieties, with the respective values for Faida beans being 7.61 mm, 0.74 g/cm3, 1.28 g/cm3, and RM 01 beans having 7.82 mm, 0.77 g/cm3, 1.29 g/cm3. RM 01 bean varieties exhibited significantly higher (P < 0.05) length (8.48mm) compared to Faida beans (6.97mm) as well as thickness. The Faida variety showed significantly higher seed weight (57.82g) than RM 01 variety (55.87g). The protein content of RM 01 (22.48%) was significantly higher than that of Faida bean variety (20.90%). Faida contained lower crude fat and crude fiber compared to RM 01. The Faida bean variety had significantly higher (p<0.05) iron (61.5 mg/kg) and zinc (26.8 mg/kg) content compared to the RM 01 bean variety, which contained 49.3 mg/kg of iron and 21.3 mg/kg of zinc. Faida beans had significantly high levels of phytates (11.70 mg/g) and tannins (4.39 mg CE/g) compared to RM 01 (7.60 mg/g) and (4.08 mg CE/g) respectively. However, Faida bean varieties exhibited lower raffinose content (414.83mg/100g) and stachyose (1702.01 mg/100g) content compared to RM 01 beans which had (489.15mg/100g) and (1813.95 mg/100g) for raffinose and stachyose, respectively. Phytate to iron molar ratio for Faida was 17.08 and RM 01 was 15.19 while the phytate to zinc molar ratio was 42.26 and 35.36 for Faida and RM 01, respectively. The RM 01 bean variety had iron bio-accessibility of 35% and zinc bio-accessibility of 65% compared to the Faida bean variety which had bio-accessibility of 29% and 42% for iron and zinc, respectively. Both varieties cook (unsoaked) in less than 2 h hence they are easy to cook. Upon cooking after soaking in distilled water, RM 01 bean variety cooked faster. Soaking in Na2CO3 solution followed by cooking significantly reduced the cooking times of the two bean varieties by 50% were compared to unsoaked beans. In conclusion, both Faida and RM 01 bean varieties demonstrated desirable physicochemical and nutritional properties, with RM 01 exhibiting higher protein content, better iron and zinc bio-accessibility, and faster cooking time, especially after soaking. Faida, on the other hand, had higher mineral content but also higher levels of anti-nutrients such as phytates and tannins. Soaking in Na₂CO₃ solution significantly reduced cooking time for both varieties. These findings highlight the potential of these improved bean varieties for enhancing food and nutrition security in Kenya, particularly in promoting quick-cooking and nutrient-dense legumes.