Physico-Chemical Characteristics of Sweet Lupin-Based Yoghurt Like Product Made Using Folate Producing Lactic Acid Bacteria

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Addis Ababa University


Lupins are important crops as rich sources of protein, minerals, dietary fiber and so on. Among the legumes lupin is underutilized due to the presence of bitter and toxic alkaloids. In recent years, genetically improved sweet lupin variety with low alkaloid level is released. Yet, the consumption of sweet lupin is very low. Specially in developing countries due to lack of food products made with sweet lupin, it still remains being a neglected crop. Therefore, this study aimed to develop yoghurt like product from sweet lupin (Lupin luteus) using folate producing lactic acid bacteria. Cleaned sweet lupin seeds were soaked in water (1:9) for 12hrs. Then, the seeds were grounded into a slurry and mixed with water (1:1) followed by pasteurization at 90oC for 15min. The pasteurized slurry was subjected to fermentation using highly folate producing Lactobacillus plantarum strain with 3% of inoculum for 48hrs. Then, the proximate, mineral and folate composition of the formulated sweet lupin-based yoghurt like product was assessed. Also, physico-chemical characteristics, sensory quality of the product were evaluated. Accordingly, the hull weight of the seed was 20.60% and the water holding capacity of the seed and flour were 460 and 310%, respectively. The foaming capacity and stability of the flour were 12 and 10 %, respectively with bulk density of 0.779 g/ml. The raw sweet lupin had a moisture, crude protein, crude fat, crude fiber, total ash, total carbohydrate and gross energy contents were 8.10, 35.28, 9.36, 3.61, 3.03, 44.23 %, and 402.28 (Kcal/100gm), respectively. The yoghurt-like product had percentage value of 19.87%, 36.39, 8.95, 2.63, 2.07, 32.13 and 354.76 (Kcal/100gm) of the aforementioned nutrients, respectively. The phytate, alkaloid and tannin concentrations in the raw sweet lupin were 0.60, 0.12 and 0.05 %, respectively. While in fermented product the concentrations of the anti-nutrients were 0.16, 0.02 and 0.01 %, respectively (p≤ 0.05). The concentration of the minerals sodium, potassium and calcium in the raw sweet lupin seed were 10.36, 4.74 and 27.78 mg/100gm on dry basis, respectively. Whereas concentrations of the same minerals in the fermented yoghurt like product were 3.11,1.75 and 15.75 mg/100gm, respectively (p≤ 0.05). The concentration of the minerals iron, zinc and manganese in the raw seed and fermented product were 7.71,0.21, 0.84,0.46 and 4.4,3.75 mg/100g, respectively. The pH and titratable acidity of the raw slurry and fermented product were 5.8,0.66% and 4.8,0.99%, respectively. Folate content in raw seed was 83.02 μg/100g and was reduced to 19.45 μg/100g, during pasteurization of the slurry at 90oC for 15min. The final fermented sweet lupin-based yoghurt like product had a folate concentration of 35.96μg/100g. The viscosity of the fermented product was 309.29 (mPa-s) and the color evaluated using L*a*b* was 112.09, 96.9 and 34.81, respectively. As a new product the sensory quality of the yoghurt like product was evaluated. Accordingly, there was no significant difference in sensory attributes of texture and overall acceptability between sweet lupin yoghurt like product with sweet lupin yoghurt like product with vanilla (p≥ 0.05). Vanilla (flavoring agent) incorporated (1%)of fermented product had a higher sensory score in attributes of mouthfeel (consistency), color, flavor and taste, than the sweet lupin-based yoghurt like product. In conclusion, this study demonstrated the potential of sweet lupin to produce fermented yoghurt like product with comparable sensory acceptability providing vital nutrients such as folate and reduced anti-nutritional factors. Future studies on optimizing the processing to formulate a more acceptable product along with shelf life are recommended.



Sweet Lupin, Yoghurt-Like, Fermentation, Folate, Anti-Nutrients, Mineral