Hydroponic Cultivation Improves the Nutritional Quality of Soybean and Its Products

TLDR

Hydroponic cultivation offers precise environmental control, water savings, higher productivity, and disease prevention, and could enable soybean protein and oil production under adverse conditions. The study compares the composition of four soybean cultivars and their derivatives (soy milk and okara) grown hydroponically to those grown in open‑field soil. The authors measured proximate composition, phytic acid, and isoflavone concentrations in seeds, soy milk, and okara from both cultivation systems. Hydroponic cultivation increased fat and dietary fiber, reduced isoflavones, left protein unchanged, improved seed nutritional quality, with effects seen in okara but not soy milk, indicating cultivar selection can tailor desired traits.

Abstract

Hydroponic cultivation allows the control of environmental conditions, saves irrigation water, increases productivity, and prevents plant infections. The use of this technique for large commodities such as soybean is not a relevant issue on fertile soils, but hydroponic soybean cultivation could provide proteins and oil in adverse environmental conditions. In this paper, the compositions of four cultivars of soybean seeds and their derivates, soy milk and okara, grown hydroponically were compared to that of the same cultivar obtained from soil cultivation in an open field. Besides proximal composition, the concentrations of phytic acid and isoflavones were monitored in the seeds, soy milk, and okara. Results demonstrated that, independent from the cultivar, hydroponic compared to soil cultivation promoted the accumulation of fats (from 17.37 to 21.94 g/100 g dry matter) and total dietary fiber (from 21.67 to 28.46 g/100 g dry matter) and reduced isoflavones concentration (from 17.04 to 7.66 mg/kg dry matter), whereas protein concentration was unaffected. The differences found in seed composition were confirmed in the respective okara products, but the effect of cultivation system was not significant looking at the soy milk composition. Data showed that hydroponic cultivation improved the nutritional quality of soybean seeds with regard to fats and dietary fiber. They also suggest that specific cultivars should be selected to obtain the desired nutritional features of the soybean raw material depending on its final destination.