Persimmon Fruit Powder May Substitute Indolbi, a Synthetic Growth Regulator, in Soybean Sprout Cultivation

Abstract

Soybean sprouts are a major food item in Korea. Various studies have been carried out to enhance their yield and nutritional values. The objective of the present study was to examine the influence of persimmon fruit powder and Indolbi, a synthetic plant growth regulator, on the yield and nutritional value of soybean sprouts. Seeds were soaked in tap water containing 0.5%, 1.0%, 2.5% and 5.0% (w/v) persimmon fruit powder and the samples were named as PT-1, PT-2, PT-3, and PT-4, respectively. The yield increment was almost doubled in PT-3 and PT-4 than in the Indolbi treated sprouts on basis of the control. Vitamin C, isoflavones, and total phenolic contents as well as antioxidant potentials (determined by 1,1-diphenyl-2-picrylhydrazyl and superoxide anion radical scavenging assays) were also significantly (p < 0.05) higher in PT-3 compared to the Indolbi treatment and the control. However, total free amino acid and magnesium contents of Indolbi- applied sprouts were higher than in the fruit powder treatments. The overall results of the present study showed that persimmon fruit powder can be an option to enhance the yield and nutritional value of soybean sprouts since, due to potential health hazards, the use of synthetic chemicals like Indolbi is less preferred than the natural products.

Pu-erh Tea Extract Treatment Could Be an Efficient Way to Enhance the Yield and Nutritional Value of Soybean Sprout

“…Pu-erh tea extract treatment significantly influenced various physicochemical characteristics of soybean sprouts ( Supplementary Table S1 ). Although the content of specific plant growth regulators in Pu-erh tea was not measured in the present study, it can be implied that some growth-promoting substances might have played a role in increasing the yield and nutrient content of the tea extract-treated soybean sprouts as in previous studies with the extracts of persimmon fruit powder [ 21 ], brown seaweed [ 24 ], lacquer stem [ 25 ], and ginseng [ 20 ]. This enhancement might be due to the absorption of various phytochemicals of Pu-erh tea [ 27 , 28 ] during seed-soaking and the subsequent physiological and biochemical mechanisms that took place during sprout growth [ 29 ].…”

“…One of the reasons for elevated isoflavones might be owing to the increased phenylalanine content and thereby the isoflavone synthetase activities [ 7 , 39 ] due to the tea treatment. Soybean seed soaking with persimmon fruit powder extract also increased the isoflavone content of soybean sprouts [ 21 ]. Soy isoflavones are beneficial in preventing aging, cardiovascular diseases, and cancer because of their potential ability to scavenge the free radicals from the human body [ 40 ].…”

“…The moisture content of soybean sprout was estimated following the method described earlier [17,21]. Five grams of freshly harvested sprouts were oven-dried (60 • C) to constant weight, and the moisture content was determined using the following equation:…”

“…Gamma irradiation increases the microbial safety of soybean seeds and sprouts by reducing the risk of foodborne pathogens [ 15 ]; the spraying of zinc sulfate solution enhances the zinc content of soybean sprouts [ 16 ]; different light treatments manipulate the isoflavone contents of soybean sprouts [ 17 ]; the inoculation of bacterial strains affects the bioactive compounds and antioxidant potentials of soybean sprouts [ 18 ]; spraying grapefruit seed extract, chitosan, and phosphate buffer improves soybean sprout yield and inhibits sprout rot [ 19 ]; treatment with the medicinal plant ginseng increases the growth as well as the amino acid and organic acid content of soybean sprouts [ 20 ]. Soaking soybean seeds in persimmon fruit powder enhances the yield and nutritional value (vitamin C, isoflavone, and total phenolic content) of soybean sprouts [ 21 ]. The germination of brown rice in red onion solution increases the antioxidant capacity and GABA content as well as makes the rice slightly softer and stickier than that germinated in water [ 22 ].…”

“…Although the use of a few synthetic plant growth regulators, such as Indolbi and 6-benzylaminopurine, to enhance the yield and nutritional values of soybean sprouts are in practice [ 23 ], due to potential health hazards, consumers are reluctant to accept such synthetic chemical-treated food products. Since a few studies show that the use of different plant products such as persimmon fruit powder [ 21 ], brown seaweed [ 24 ], lacquer stem [ 25 ], and ginseng [ 20 ] can significantly enhance the yield and/or nutritional value of soybean sprouts, the exploration of natural products to enrich the food quality is of great significance.…”