Comparison of γ-aminobutyric acid and isoflavone aglycone contents, to radical scavenging activities of high-protein soybean sprouting by lactic acid fermentation with Lactobacillus brevis

국문 초록 (Abstract)

본 연구는 발아된 고단백 콩(high protein soybeans, HPSs)으로부터 가바(GABA)와 비배당체 이소플라본(isoflavone aglycones)이 증가된 콩-분말 요구르트(SPY)를 제조하였다. 이를 위해 L. brevis로 발효 증자 고단백콩 발아체(FSHPS, 0-4 cm)를 72시간 발효하였다. 발효 고단백콩(FHPS), 0 cm 발효 증자 고단백콩 발아체(FSHPS-0), 1cm 발효 증자 고단백콩 발아체(FSHPS-1), 2cm 발효 증자 고단백콩 발아체(FSHPS-2) 및 4 cm 발효 증자 고단백콩 발아체(FSHPS-4)의 총 유리아미노산 함량은 각 79.53, 489.93, 877.55, 780.53 및 979.97 mg 이었다. 발효되지 않은 고단백콩 발아체(UFSHPS-1, 1 cm) 및 FSHPS-1의 글루탐산(GA) 및 GABA 함량이 각각 최고 100.31 mg/100 mL 및 101.60 mg/100 mL로 관찰되었다. 또한 FSHPS-1에서 가장 높은 DPPH(63.28%) 및 ABTS(73.28%) 라디칼 소거능을 보였다. 그러나 FSHPS-4에서 isoflavone aglycone 비율이 81.63%로 가장 높았다. 특히, FSHPS-1은 높은 가바 함량과 기능적 특성을 나타내어 두유 산업에 응용할 수 있을 것이다.

다국어 초록 (Multilingual Abstract)

In this study, soy-powder yogurt (SPY) with enhanced levels of ${\gamma}$-aminobutyric acid (GABA) and isoflavone aglycone was produced from sprouting high-protein soybeans (HPSs). The fermented steam-HPS sprouts (0 to 4 cm) were fermented (72 h) with Lactobacillus brevis, and the total free amino acids (FAAs) of the formed mixtures were determined to be 79.53, 489.93, 877.55, 780.53, and 979.97 mg/100 mL in the fermented HPS (FHPS), and the fermented steam-HPS with 0 cm (FSHPS-0), 1 cm (FSHPS-1), 2 cm (FSHPS-2), and 4 cm sprouting lengths (FSHPS-4), respectively. The levels of glutamic acid (GA) and GABA were observed to be the highest, 100.31 and 101.60 mg/100 mL, respectively, in the unfermented HPS (UFSHPS-1, 1 cm) and FSHPS-1 sprouts, respectively. Moreover, the total contents of the isoflavone glycoside form decreased proportionally to the increasing total levels of isoflavone aglycones after fermentation in FSHPS-0, FSHPS-1, FSHPS-2, and FSHPS-4. The levels of isoflavone aglycones were detected as 350.34, 289.15, 361.61, 445.05, and $491.25{\mu}g/g$ in FHPS, FSHPS-0, FSHPS-1, FSHPS-2, and FSHPS-4, respectively. While FSHPS-1 exhibited the highest DPPH (63.28%) and ABTS (73.28%) radical scavenging activities, FSHPS-4 contained the highest isoflavone aglycone ratio (81.63%). All in all, the FSHPS-1 mixture prepared in this study exhibited high GABA content and functional prosperity, thereby making it suitable for potential applications in the soy-dairy industry.