Changes in the Bioactive Compounds Content of Soybean as a Function of Grain Moisture Content and Temperature during Long‐Term Storage

Abstract

Soybean is a rich source of bioactive compounds, such as phenolic acids, flavonoids, isoflavones, carotenoids, and tocopherols. The amount of bioactive compounds in freshly harvested soybeans and their derived products has been determined; however, when they are used in the food industry, soybeans are generally stored prior to being processed. This study aimed to evaluate the effects of soybean moisture content (12%, 15%, and 18%) and storage temperature (11, 18, 25, and 32 °C) on the free phenolic, total flavonoid, vanillic acid, total carotenoid, and δ- and γ-tocopherol content of soybeans stored for 12 mo. Moreover, the ABTS and DPPH radical scavenging activities of phenolic extracts were determined. There was an increase in free phenolics and total flavonoids in the stored grains compared with the grains on the 1st d of storage. Vanillic acid showed a decrease in soybeans stored at 15% and 18% moisture content and 25 or 32 °C, which indicated some degradation into other metabolites. Total carotenoid content decreased as a function of storage temperature and showed some temperature-dependent degradation. The δ- and γ-tocopherol content also tended to decrease in grains stored at 15% or 18% moisture content or 25 or 32 °C, regardless of the moisture content studied.

Pigmented rice oil: Changes in oxidative stability and bioactive compounds during storage of whole grains

“…The abovementioned decreases represented total tocopherol reductions of 13.60, 17.06, and 32.45% for the oils extracted from grains with brown, black, and red pericarps, respectively. Reductions in the γ‐ and δ‐tocopherol were also reported by Ziegler et al () in oil extracted from soybean grains stored for 12 months at 12, 15, and 18% of moisture at 32 °C. The reduction in tocopherol content was due to the ability of these compounds to eliminate free radicals formed by lipid oxidation reactions; therefore, the higher the degree of oxidation of lipids, the more tocopherols are used to inhibit oxidation, causing their concentration to decrease (Rossi, Alamprese, & Ratti ).…”

“…Storage at 40 °C caused 23.68, 19.85, and 33.66% reductions in total carotenoid content, for grains with brown, black, and red pericarps, respectively. Ziegler et al () also found that total carotenoid content reduced in oil extracted from soybeans stored at 12, 15, and 18% humidity and at 32 °C for 12 months. The reduction in total carotenoids is attributed to lipid oxidation, which was more prevalent during storage at 40 °C (Table ).…”

“…Oil was extracted in triplicate from a 150 g milled sample with petroleum ether using a Soxhlet apparatus continuously for 8 h. The solvent was removed using a rotary evaporator (Heidolph, Laborota Model 4000, Kelheim, Bavaria, Germany) under vacuum at 35 °C. The oil was collected in vials and stored at −18 °C (Ziegler, Vanier, Ferreira, Paraginski, Monks, & Elias, ). The oil content was determined following the method 30‐20 from the American Association of Cereal Chemists (AACC, ).…”

Kiwifruit Alleviates Learning and Memory Deficits Induced by Pb through Antioxidation and Inhibition of Microglia Activation In Vitro and In Vivo

“…Total antioxidant activity of five cultivars of kiwifruit powder was first assessed on the basis of the radical scavenging effect of the 1,1-diphenyl-2-picrylhydrazyl- (DPPH-) free radical activity [7]. Different concentration of different species of kiwifruit powder or vitamin C (the positive control) was prepared in methanol.…”

“…Oxidative stress has been demonstrated as one of the crucial mechanisms of cognitive deficits of Pb [6, 7]. Oxidative stress is an unbalanced status between the generation of reactive oxygen species (ROS) and antioxidant defense system.…”